Nanomaterial (NM) bioactivity profiling by ToxCast high-throughput screening (HTS)

EPA Science Inventory

Rapidly increasing numbers of new NMs and their uses demand efficient tests of NM bioactivity for safety assessment. The EPA’s ToxCast program uses HTS assays to prioritize for targeted testing, identify biological pathways affected, and aid in linking NM properties and potential...

NCCT ToxCast Program for Nanomaterial Prioritization: High-Throughput Screening, Consideration of Exposure, and Bioactivity Profiling/Modeling

EPA Science Inventory

Find relationships between bioactivities and NM characteristics or testing conditions. Recommend a dose metric for NMs in vitro studies. Establish associations to in vivo toxicity or pathways identified from testing of conventional chemicals with ToxCast HTS methods. May be abl...

In Vitro Screening of Environmental Chemicals for Targeted Testing Prioritization: The ToxCast Project

EPA Science Inventory

Chemical toxicity testing is being transformed by advances in biology and computer modeling, concerns over animal use, and the thousands of environmental chemicals lacking toxicity data. The U.S. Environmental Protection Agency’s ToxCast program aims to address these concerns by ...

Screening Chemicals for Estrogen Receptor Bioactivity Using a Computational Model.

PubMed

Browne, Patience; Judson, Richard S; Casey, Warren M; Kleinstreuer, Nicole C; Thomas, Russell S

2015-07-21

The U.S. Environmental Protection Agency (EPA) is considering high-throughput and computational methods to evaluate the endocrine bioactivity of environmental chemicals. Here we describe a multistep, performance-based validation of new methods and demonstrate that these new tools are sufficiently robust to be used in the Endocrine Disruptor Screening Program (EDSP). Results from 18 estrogen receptor (ER) ToxCast high-throughput screening assays were integrated into a computational model that can discriminate bioactivity from assay-specific interference and cytotoxicity. Model scores range from 0 (no activity) to 1 (bioactivity of 17β-estradiol). ToxCast ER model performance was evaluated for reference chemicals, as well as results of EDSP Tier 1 screening assays in current practice. The ToxCast ER model accuracy was 86% to 93% when compared to reference chemicals and predicted results of EDSP Tier 1 guideline and other uterotrophic studies with 84% to 100% accuracy. The performance of high-throughput assays and ToxCast ER model predictions demonstrates that these methods correctly identify active and inactive reference chemicals, provide a measure of relative ER bioactivity, and rapidly identify chemicals with potential endocrine bioactivities for additional screening and testing. EPA is accepting ToxCast ER model data for 1812 chemicals as alternatives for EDSP Tier 1 ER binding, ER transactivation, and uterotrophic assays.

Linking ToxCast Signatures with Functional Consequences: Proof-of-Concept Study using Known Inhibitors of Vascular Development

EPA Science Inventory

The USEPA’s ToxCast program is developing a novel approach to chemical toxicity testing using high-throughput screening (HTS) assays to rapidly test thousands of chemicals against hundreds of in vitro molecular targets. This approach is based on the premise that in vitro HTS bioa...

High Throughput Prioritization for Integrated Toxicity Testing Based on ToxCast Chemical Profiling

EPA Science Inventory

The rational prioritization of chemicals for integrated toxicity testing is a central goal of the U.S. EPA’s ToxCast™ program (http://epa.gov/ncct/toxcast/). ToxCast includes a wide-ranging battery of over 500 in vitro high-throughput screening assays which in Phase I was used to...

ToxCast: Using high throughput screening to identify profiles of biological activity

EPA Science Inventory

ToxCast, the United States Environmental Protection Agency’s chemical prioritization research program, is developing methods for utilizing computational chemistry and bioactivity profiling to predict potential for toxicity and prioritize limited testing resources (www.epa.gov/toc...

High-Throughput Screening in ToxCast/Tox21 (FutureToxII)

EPA Science Inventory

Addressing safety aspects of drugs and environmental chemicals relies extensively on animal testing. However, the quantity of chemicals needing assessment and challenges of species extrapolation require development of alternative approaches. The EPA’s ToxCast program addresses th...

Predictive In Vitro Screening of Environmental Chemicals – The ToxCast Project

EPA Science Inventory

ToxCast, the United States Environmental Protection Agency’s chemical prioritization research program, is developing methods for utilizing computational chemistry and bioactivity profiling to predict potential for toxicity and prioritize limited testing resources (www.epa.gov/toc...

Comparison of diverse nanomaterial bioactivity profiles based on high-throughput screening (HTS) in ToxCast™ (FutureToxII)

EPA Science Inventory

Most nanomaterials (NMs) in commerce lack hazard data. Efficient NM testing requires suitable toxicity tests for prioritization of NMs to be tested. The EPA’s ToxCast program is screening NM bioactivities and ranking NMs by their bioactivities to inform targeted testing planning....

Composites for Advanced Space Transportation Systems (CASTS)

NASA Technical Reports Server (NTRS)

Davis, J. G., Jr. (Compiler)

1979-01-01

A summary is given of the in-house and contract work accomplished under the CASTS Project. In July 1975 the CASTS Project was initiated to develop graphite fiber/polyimide matrix (GR/PI) composite structures with 589K (600 F) operational capability for application to aerospace vehicles. Major tasks include: (1) screening composites and adhesives, (2) developing fabrication procedures and specifications, (3) developing design allowables test methods and data, and (4) design and test of structural elements and construction of an aft body flap for the Space Shuttle Orbiter Vehicle which will be ground tested. Portions of the information are from ongoing research and must be considered preliminary. The CASTS Project is scheduled to be completed in September 1983.

Secondary Waste Form Screening Test Results—Cast Stone and Alkali Alumino-Silicate Geopolymer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pierce, Eric M.; Cantrell, Kirk J.; Westsik, Joseph H.

2010-06-28

PNNL is conducting screening tests on the candidate waste forms to provide a basis for comparison and to resolve the formulation and data needs identified in the literature review. This report documents the screening test results on the Cast Stone cementitious waste form and the Geopolymer waste form. Test results suggest that both the Cast Stone and Geopolymer appear to be viable waste forms for the solidification of the secondary liquid wastes to be treated in the ETF. The diffusivity for technetium from the Cast Stone monoliths was in the range of 1.2 × 10-11 to 2.3 × 10-13 cm2/smore » during the 63 days of testing. The diffusivity for technetium from the Geopolymer was in the range of 1.7 × 10-10 to 3.8 × 10-12 cm2/s through the 63 days of the test. These values compare with a target of 1 × 10-9 cm2/s or less. The Geopolymer continues to show some fabrication issues with the diffusivities ranging from 1.7 × 10-10 to 3.8 × 10-12 cm2/s for the better-performing batch to from 1.2 × 10-9 to 1.8 × 10-11 cm2/s for the poorer-performing batch. In the future more comprehensive and longer term performance testing will be conducted, to further evaluate whether or not these waste forms will meet the regulation and performance criteria needed to cost-effectively dispose of secondary wastes.« less

ExpoCast: Exposure Science for Prioritization and Toxicity Testing (S)

EPA Science Inventory

The US EPA is completing the Phase I pilot for a chemical prioritization research program, called ToxCast. Here EPA is developing methods for using computational chemistry, high-throughput screening, and toxicogenomic technologies to predict potential toxicity and prioritize limi...

ExpoCast: Exposure Science for Prioritization and Toxicity Testing

EPA Science Inventory

The US EPA is completing the Phase I pilot for a chemical prioritization research program, called ToxCastTM. Here EPA is developing methods for using computational chemistry, high-throughput screening, and toxicogenomic technologies to predict potential toxicity and prioritize l...

Letter Report: LAW Simulant Development for Cast Stone Screening Test

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Renee L.; Westsik, Joseph H.; Swanberg, David J.

2013-03-27

More than 56 million gallons of radioactive and hazardous waste are stored in 177 underground storage tanks at the U.S. Department of Energy’s (DOE’s) Hanford Site in southeastern Washington State. The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is being constructed to treat the wastes and immobilize them in a glass waste form. The WTP includes a pretreatment facility to separate the wastes into a small volume of high-level waste (HLW) containing most of the radioactivity and a larger volume of low-activity waste (LAW) containing most of the nonradioactive chemicals. The HLW will be converted to glass in themore » HLW vitrification facility for ultimate disposal at an offsite federal repository. At least a portion (~35%) of the LAW will be converted to glass in the LAW vitrification facility and will be disposed of onsite at the Integrated Disposal Facility (IDF). The pretreatment and HLW vitrification facilities will have the capacity to treat and immobilize the wastes destined for each facility. However, a second facility will be needed for the expected volume of additional LAW requiring immobilization. A cementitious waste form known as Cast Stone is being considered to provide the required additional LAW immobilization capacity. The Cast Stone waste form must be acceptable for disposal in the IDF. The Cast Stone waste form and immobilization process must be tested to demonstrate that the final Cast Stone waste form can comply with waste acceptance criteria for the IDF disposal facility and that the immobilization processes can be controlled to consistently provide an acceptable waste form product. Further, the waste form must be tested to provide the technical basis for understanding the long term performance of the waste form in the IDF disposal environment. These waste form performance data are needed to support risk assessment and performance assessment (PA) analyses of the long-term environmental impact of the waste disposal in the IDF. A testing program was developed in fiscal year (FY) 2012 describing in some detail the work needed to develop and qualify Cast Stone as a waste form for the solidification of Hanford LAW (Westsik et al. 2012). Included within Westsik et al. (2012) is a section on the near-term needs to address Tri-Party Agreement Milestone M-062-40ZZ. The objectives of the testing program to be conducted in FY 2013 and FY 2014 are to: • Determine an acceptable formulation for the LAW Cast Stone waste form. • Evaluate sources of dry materials for preparing the LAW Cast Stone. • Demonstrate the robustness of the Cast Stone waste form for a range of LAW compositions. • Demonstrate the robustness of the formulation for variability in the Cast Stone process. • Provide Cast Stone contaminant release data for PA and risk assessment evaluations. The first step in determining an acceptable formulation for the LAW Cast Stone waste form is to conduct screening tests to examine expected ranges in pretreated LAW composition, waste stream concentrations, dry-materials sources, and mix ratios of waste feed to dry blend. A statistically designed test matrix will be used to evaluate the effects of these key parameters on the properties of the Cast Stone as it is initially prepared and after curing. The second phase of testing will focus on selection of a baseline Cast Stone formulation for LAW and demonstrating that Cast Stone can meet expected waste form requirements for disposal in the IDF. It is expected that this testing will use the results of the screening tests to define a smaller suite of tests to refine the composition of the baseline Cast Stone formulation (e.g. waste concentration, water to dry mix ratio, waste loading).« less

Validation, acceptance, and extension of a predictive model of reproductive toxicity using ToxCast data

EPA Science Inventory

The EPA ToxCast research program uses a high-throughput screening (HTS) approach for predicting the toxicity of large numbers of chemicals. Phase-I tested 309 well-characterized chemicals (mostly pesticides) in over 500 assays of different molecular targets, cellular responses an...

In Vitro Bioactivity in ToxCast Assays for Fruit and Vegetable Juices (TDS)

EPA Science Inventory

The ToxCast and Tox21 programs have generated in vitro screening data for over 1000 chemicals to aid in hazard identification and setting chemical testing priorities. These data, together with in vitro pharmacokinetic data, are used to infer possible toxic responses and external ...

Predictive Modeling of Apical Toxicity Endpoints Using Data From ToxCast

EPA Science Inventory

The US EPA and other regulatory agencies face a daunting challenge of evaluating potential toxicity for tens of thousands of environmental chemicals about which little is currently known. The EPA’s ToxCast program is testing a novel approach to this problem by screening compounds...

Building Structure Feature-based Models for Predicting Isoform-specific Human Cytochrome P-450 (hCYP 3A4, 2D6 and 2C9) Inhibition Assay Results in ToxCast

EPA Science Inventory

EPA’s ToxCast project is using high-throughput screening (HTS) to profile and prioritize chemicals for further testing. ToxCast Phase I evaluated 309 unique chemicals, the majority pesticide actives, in over 500 HTS assays. These included 3 human cytochrome P450 (hCYP3A4, hCYP2...

ToxCast Workflow: High-throughput screening assay data processing, analysis and management (SOT)

EPA Science Inventory

US EPA’s ToxCast program is generating data in high-throughput screening (HTS) and high-content screening (HCS) assays for thousands of environmental chemicals, for use in developing predictive toxicity models. Currently the ToxCast screening program includes over 1800 unique c...

ACToR - Aggregated Computational Toxicology Resource ...

EPA Pesticide Factsheets

There are too many uncharacterized environmental chemicals to test with current in vivo protocols. Develop predictive in vitro screening assays that can be used to prioritize chemicals for detailed testing. ToxCast program requires large amounts of data: In vitro assays (mainly generated by ToxCast program) and In vivo data to develop and validate predictive signatures ACToR is compiling both sets of data for use in predictive algorithms.

Cheminformatics and Data Mining Approaches for Exploring the Alternatives Testing Landscsape: Case Studies in ToxCast and Skin Sensitization (BOSC CSS)

EPA Science Inventory

Cheminformatics approaches and structure-based rules are being used to evaluate and explore the ToxCast chemical landscape and associated high-throughput screening (HTS) data. We have shown that the library provides comprehensive coverage of the knowledge domains and target inven...

Analysis of Chemical Bioactivity through In Vitro Profiling using ToxCast and Tox21 High-Throughput Screening (China tox. conf. TATT)

EPA Science Inventory

Safety assessment of drugs and environmental chemicals relies extensively on animal testing. However, the quantity of chemicals needing assessment and challenges of species extrapolation drive the development of alternative approaches. The EPA’s ToxCast and the multiagency Tox21 ...

Predicting Developmental Toxicity of ToxCast Phase I Chemicals Using Human Embryonic Stem Cells and Metabolomics

EPA Science Inventory

EPA’s ToxRefDB contains prenatal guideline study data from rats and rabbits for over 240 chemicals that overlap with the ToxCast in vitro high throughput screening project. A subset of these compounds were tested in Stemina Biomarker Discovery's developmental toxicity platform, a...

Endocrine Profiling and Prioritization of Environmental Chemicals Using ToxCast Data

EPA Science Inventory

The prioritization of chemicals for toxicity testing is a primary goal of the U.S. EPA’s ToxCast™ program. Phase I of ToxCast utilized a battery of 467 in vitro, high-throughput screening assays to assess 309 environmental chemicals. One important mode of action leading to toxici...

Using high-content imaging data from ToxCast to analyze toxicological tipping points (TDS)

EPA Science Inventory

Translating results obtained from high-throughput screening to risk assessment is vital for reducing dependence on animal testing. We studied the effects of 976 chemicals (ToxCast Phase I and II) in HepG2 cells using high-content imaging (HCI) to measure dose and time-depende...

Endocrine Profiling and Prioritization Using ToxCast Assays

EPA Science Inventory

The U.S. EPA's Endocrine Disruptor Screening Program (EDSP) is charged with screening pesticide chemicals and environmental contaminants for their potential to affect the endocrine systems of humans and wildlife (http://www.epa.gov/endo/). The prioritization of chemicals for test...

Prioritizing Environmental Chemicals for Obesity and Diabetes ...

EPA Pesticide Factsheets

Background: Diabetes and obesity are major threats to public health in the US and abroad. Understanding the role chemicals in our environment play in the development of these conditions is an emerging issue in environmental health, although identifying and prioritizing chemicals for testing beyond those already implicated in the literature is a challenge. This review is intended to help researchers generate hypotheses about chemicals potentially contributing to diabetes and obesity-related health outcomes by summarizing relevant findings from the US Environmental Protection Agency (EPA) ToxCast high-throughput screening (HTS) program. Objectives: To develop new hypotheses around environmental chemicals of potential interest for diabetes- or obesity-related outcomes using high throughput screening data. Methods: Identify ToxCast assay targets relevant to several biological processes related to diabetes and obesity (insulin sensitivity in peripheral tissue, pancreatic islet and beta cell function, adipocyte dierentiation, and feeding behavior) and present chemical screening data against those assay targets to identify chemicals of potential interest. Discussion: Results of this screening-level analysis suggest that the spectrum of environmental chemicals to consider in research related to diabetes and obesity is much broader than indicated from research papers and reviews published in the peer-reviewed literature. Testing of hypotheses based on ToxCast data will a

High-throughput screening, predictive modeling and computational embryology - Abstract

EPA Science Inventory

High-throughput screening (HTS) studies are providing a rich source of data that can be applied to chemical profiling to address sensitivity and specificity of molecular targets, biological pathways, cellular and developmental processes. EPA’s ToxCast project is testing 960 uniq...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cozzi, A.; Crawford, C.; Fox, K.

More than 56 million gallons of radioactive and hazardous waste are stored in 177 underground storage tanks at the U.S. Department of Energy’s (DOE’s) Hanford Site in Washington State. The HLW will be vitrified in the HLW facility for ultimate disposal at an offsite federal repository. A portion (~35%) of the LAW will be vitrified in the LAW vitrification facility for disposal onsite at the Integrated Disposal Facility (IDF). The pretreatment and HLW vitrification facilities will have the capacity to treat and immobilize all of the wastes destined for those facilities. However, a second facility will be needed for themore » expected volume of LAW requiring immobilization. Cast Stone, a cementitious waste form, is being considered to provide the required additional LAW immobilization capacity. The Cast Stone waste form must be acceptable for disposal in the IDF. The Cast Stone waste form and immobilization process must be tested to demonstrate that the final Cast Stone waste form can comply with the waste acceptance criteria for the disposal facility and that the immobilization processes can be controlled to consistently provide an acceptable waste form product. A testing program was developed in fiscal year (FY) 2012 describing in detail the work needed to develop and qualify Cast Stone as a waste form for the solidification of Hanford LAW. A statistically designed test matrix was used to evaluate the effects of key parameters on the properties of the Cast Stone as it is initially prepared and after curing. For the processing properties, the water-to-dry-blend mix ratio was the most significant parameter in affecting the range of values observed for each property. The single shell tank (SST) Blend simulant also showed differences in measured properties compared to the other three simulants tested. A review of the testing matrix and results indicated that an additional set of tests would be beneficial to improve the understanding of the impacts noted in the Screening Matrix tests. A set of Cast Stone formulations were devised to augment the original screening test matrix and focus on the range of the test conditions. Fly ash and blast furnace slag were limited to either northwest or southeast and the salt solutions were narrowed to the Average and the SST Blend at the 7.8M Na concentration. To fill in the matrix, a mix ratio of 0.5 was added. In addition, two admixtures, Xypex Admix C-500 and Rheomac SF100 (silica fume), were added as an additional dry material binder in select compositions. As in the Screening Matrix, both fresh and cured properties were evaluated for the formulations. In this study, properties that were influenced by the W/DM ratio in the Screening Matrix; flow diameter, plastic viscosity, density, and compressive strength, showed consistent behavior with respect to W/DM. The leach index for highly soluble components, sodium and nitrate, were not influenced by changes in formulation or the admixtures. The leach index for both iodine and Tc-99 show an influence from the addition of the admixture, Xypex Admix C-500. Additional testing should be performed to further evaluate the influence of Xypex Admix C-500 on the leach index over a range of admixture concentrations, Cast Stone formulations, and curing and storage conditions.« less

Genetic Testing in the Workplace: A Caste System for Workers?

ERIC Educational Resources Information Center

Samuels, Sheldon W.

1999-01-01

"Authorized" genetic testing may be obtained from employees with coercion or threat. Unless protections are put in place, employers and health insurers will use genetic screening to hire and fire. (JOW)

Identification of Chemical Features Linked to Thyroperoxidase ...

EPA Pesticide Factsheets

Disruption of maternal serum thyroid hormone (TH) adversely affects fetal neurodevelopment. Therefore, assay development within the US EPA ToxCast program is ongoing to enable screening for chemicals that may disrupt TH, in support of the Endocrine Disruption Screening Program (EDSP21). The AUR-TPO assay was recently developed to screen >1,000 ToxCast chemicals for potential thyroperoxidase (TPO) inhibition activity. TPO is critical for TH synthesis and is a known target of thyroid-disrupting chemicals. The bioactivity results from the AUR-TPO assay were used to identify chemical substructures associated with in vitro TPO inhibition. Substructure profiles were generated for each chemical in the ToxCast test set using the publicly-available ToxPrint 2.0 chemotypes. Chemotypes enriched among the putative TPO inhibitors were identified using a cumulative hypergeometric probability (p < 0.01). Of the total 729 chemotypes evaluated, 31 were overrepresented among TPO inhibitors. Examination of those 31 chemotypes revealed four basic pharmacophores that accounted for 70% of the ToxCast chemicals active in the AUR-TPO assay: aromatic alcohols, aromatic amines, thiocarbonyls and phosphothioates. Chemico-structural analysis of AUR-TPO screening results enabled the identification of chemical features that likely drive TPO inhibition in the AUR-TPO assay. This highlights the potential to identify thyroid-disrupting chemicals in silico using structural alerts identified by

A High-Throughput Screening Assay to Detect ...

EPA Pesticide Factsheets

In support of the Endocrine Disruption Screening Program (EDSP21), the US EPA ToxCast program is developing assays to enable screening for chemicals that may disrupt thyroid hormone synthesis. Thyroperoxidase (TPO) is critical for TH synthesis and is a known target of thyroid-disrupting chemicals that adversely impact neurodevelopment. The AUR-TPO assay was recently developed to screen >1,900 ToxCast chemicals for potential TPO inhibition activity. Parallel assays were used to determine which AUR-TPO actives were more selective for TPO inhibition. Additionally, the TPO inhibition activities of 150 chemicals were compared between the AUR-TPO assay and an orthogonal peroxidase oxidation assay using guaiacol as substrate to confirm putative TPO inhibition profiles. Bioactivity results from the AUR-TPO assay were used to identify chemical substructures associated with in vitro TPO inhibition. Substructure profiles were generated for each chemical in the ToxCast test set using the publicly-available ToxPrint 2.0 chemotypes. Chemotypes enriched among the putative TPO inhibitors were identified using a cumulative hypergeometric probability (p < 0.01). Of the total 729 chemotypes evaluated, 44 were overrepresented among TPO inhibitors. Another 24 chemotypes were found to be significantly underrepresented among AUR-TPO actives. Examination of these chemotypes revealed four basic pharmacophores that accounted for 70% of the ToxCast chemicals active in the AUR-TPO assay:

Assessing cross species conservation of ToxCast Assay targets using Sequence Alignment to Predict Across Species Susceptibility (SeqAPASS)

EPA Science Inventory

US EPA’s ToxCast program has screened thousands of chemicals in hundreds of mammalian-based HTS assays for biological activity suggestive of potential toxic effects. These data are being used to prioritize toxicity testing to focus on chemicals likely to lead to adverse health ef...

Tox21 and ToxCast Chemical Landscapes: Laying the Foundation for 21st Century Toxicology - Application of the Strategy to Chemical Testing

EPA Science Inventory

The U.S. Environmental Protection Agency’s ToxCast project and the related, multi-Agency Tox21 project are employing high-throughput technologies to screen hundreds to thousands of chemicals in hundreds of assays, probing a wide diversity of biological targets, pathways and mecha...

The ToxCast Chemical Landscape - Paving the Road to 21st Century Toxicology

EPA Science Inventory

The ToxCast high-throughput screening (HTS) program within the U.S. Environmental Protection Agency (EPA) was launched in 2007. Phase I of the program screened 310 chemicals, mostly pesticides, across hundreds of ToxCast assay endpoints. In Phase II, the ToxCast library was exp...

Identifying Toxicity Pathways with ToxCast High-Throughput Screening and Applications to Predicting Developmental Toxicity

EPA Science Inventory

Results from rodent and non-rodent prenatal developmental toxicity tests for over 300 chemicals have been curated into the relational database ToxRefDB. These same chemicals have been run in concentration-response format through over 500 high-throughput screening assays assessin...

SeqAPASS to evaluate conservation of high-throughput screening targets across non-mammalian species

EPA Science Inventory

Cell-based high-throughput screening (HTS) and computational technologies are being applied as tools for toxicity testing in the 21st century. The U.S. Environmental Protection Agency (EPA) embraced these technologies and created the ToxCast Program in 2007, which has served as a...

Evaluation of High-throughput Genotoxicity Assays Used in Profiling the US EPA ToxCast Chemicals

EPA Science Inventory

Three high-throughput screening (HTS) genotoxicity assays-GreenScreen HC GADD45a-GFP (Gentronix Ltd.), CellCiphr p53 (Cellumen Inc.) and CellSensor p53RE-bla (Invitrogen Corp.)-were used to analyze the collection of 320 predominantly pesticide active compounds being tested in Pha...

Use of High Throughput Screening Data in IARC Monograph ...

EPA Pesticide Factsheets

Purpose: Evaluation of carcinogenic mechanisms serves a critical role in IARC monograph evaluations, and can lead to “upgrade” or “downgrade” of the carcinogenicity conclusions based on human and animal evidence alone. Three recent IARC monograph Working Groups (110, 112, and 113) pioneered analysis of high throughput in vitro screening data from the U.S. Environmental Protection Agency’s ToxCast program in evaluations of carcinogenic mechanisms. Methods: For monograph 110, ToxCast assay data across multiple nuclear receptors were used to test the hypothesis that PFOA acts exclusively through the PPAR family of receptors, with activity profiles compared to several prototypical nuclear receptor-activating compounds. For monographs 112 and 113, ToxCast assays were systematically evaluated and used as an additional data stream in the overall evaluation of the mechanistic evidence. Specifically, ToxCast assays were mapped to 10 “key characteristics of carcinogens” recently identified by an IARC expert group, and chemicals’ bioactivity profiles were evaluated both in absolute terms (number of relevant assays positive for bioactivity) and relative terms (ranking with respect to other compounds evaluated by IARC, using the ToxPi methodology). Results: PFOA activates multiple nuclear receptors in addition to the PPAR family in the ToxCast assays. ToxCast assays offered substantial coverage for 5 of the 10 “key characteristics,” with the greates

Interactive high-resolution isosurface ray casting on multicore processors.

PubMed

Wang, Qin; JaJa, Joseph

2008-01-01

We present a new method for the interactive rendering of isosurfaces using ray casting on multi-core processors. This method consists of a combination of an object-order traversal that coarsely identifies possible candidate 3D data blocks for each small set of contiguous pixels, and an isosurface ray casting strategy tailored for the resulting limited-size lists of candidate 3D data blocks. While static screen partitioning is widely used in the literature, our scheme performs dynamic allocation of groups of ray casting tasks to ensure almost equal loads among the different threads running on multi-cores while maintaining spatial locality. We also make careful use of memory management environment commonly present in multi-core processors. We test our system on a two-processor Clovertown platform, each consisting of a Quad-Core 1.86-GHz Intel Xeon Processor, for a number of widely different benchmarks. The detailed experimental results show that our system is efficient and scalable, and achieves high cache performance and excellent load balancing, resulting in an overall performance that is superior to any of the previous algorithms. In fact, we achieve an interactive isosurface rendering on a 1024(2) screen for all the datasets tested up to the maximum size of the main memory of our platform.

EPA’s ToxCast Program for Predicting Toxicity and Prioritizing Chemicals for Further Screening and Testing

EPA Science Inventory

Testing of environmental and industrial chemicals for toxicity potential is a daunting task because of the wide range of possible toxicity mechanisms. Although animal testing is one means of achieving broad toxicity coverage, evaluation of large numbers of chemicals is challengin...

EPAs ToxCast Program for Predicting Toxcity and Prioritizing Chemicals for Further Screening and Testing

EPA Science Inventory

Testing of environmental and industrial chemicals for toxicity potential is a daunting task because of the wide range of possible toxicity mechanisms. Although animal testing is one means of achieving broad toxicity coverage, evaluation of large numbers of chemicals is challengin...

Development of an indirect enzyme-linked immunosorbent assay test for detecting antibodies to chicken astrovirus in chicken sera.

PubMed

Skibinska, A; Lee, A; Wylie, M; Smyth, V J; Welsh, M D; Todd, D

2015-01-01

The development of an indirect enzyme-linked immunosorbent assay (ELISA) for the serological diagnosis of Group B chicken astrovirus (CAstV) infections is described. The test was based on the use of an affinity-purified capsid antigen, specific to CAstV isolate 11672, produced as a glutathione-S-transferase N-terminal fusion protein by a recombinant baculovirus. Strongly positive ELISA signals were elicited against experimentally produced antisera raised to CAstVs from Group B (subgroups i and ii) but were negative for antisera raised to a Group A CAstV. Using a panel of 240 selected serum samples, 99% agreement was observed when the results obtained by ELISA were compared to those from an indirect immunofluorescence test for CAstV 11672. The ELISA test was applied to 68 serum sets comprising 1864 samples, which were obtained from parent and grandparent flocks originating mainly in the UK. Of the 52 sets containing ELISA-positive samples, 24 sets had >75% samples positive and nine sets had <25% samples positive and were regarded as having high and low seropositivities, respectively. Of the 1864 serum samples tested 1090 (58.5%) were ELISA positive and of these, 234 sera (21.5%) produced strongly positive signals, whereas moderately positive and weakly positive signals were produced by 562 (51.5%) and 294 (27%) sera. When used for flock screening purposes, this ELISA test can be used to (i) investigate the occurrence of first-time CAstV infections of parent flocks during lay and the possible adverse effects caused by vertically transmitted CAstV infections on broiler hatchability and performance and (ii) diagnose Group B CAstV infections within specific pathogen free flocks.

Species-Specific Predictive Signatures of Developmental Toxicity Using the ToxCast Chemical Library

EPA Science Inventory

EPA’s ToxCastTM project is profiling the in vitro bioactivity of chemicals to generate predictive signatures that correlate with observed in vivo toxicity. In vitro profiling methods from ToxCast data consist of over 600 high-throughput screening (HTS) and high-content screening ...

Modeling Reproductive Toxicity for Chemical Prioritization into an Integrated Testing Strategy

EPA Science Inventory

The EPA ToxCast research program uses a high-throughput screening (HTS) approach for predicting the toxicity of large numbers of chemicals. Phase-I tested 309 well-characterized chemicals in over 500 assays of different molecular targets, cellular responses and cell-states. Of th...

US EPA - ToxCast and the Tox21 program: perspectives

EPA Science Inventory

ToxCast is a large-scale project being conducted by the U.S. EPA to screen ~2000 chemicals against a large battery of in vitro high-throughput screening (HTS) assays. ToxCast is complemented by the Tox21 project being jointly carried out by the U.S. NIH Chemical Genomics Center (...

The Choice of Screening Instrument Matters: The Case of Problematic Cannabis Use Screening in Spanish Population of Adolescents

PubMed Central

Domingo-Salvany, Antónia; Barrio Anta, Gregorio; Sánchez Mañez, Amparo; Llorens Aleixandre, Noelia; Brime Beteta, Begoña; Vicente, Julián

2013-01-01

The aim of this study was to examine the feasibility of problem cannabis use screening instruments administration within wide school surveys, their psychometric properties, overlaps, and relationships with other variables. Students from 7 Spanish regions, aged 14–18, who attended secondary schools were sampled by two-stage cluster sampling (net sample 14,589). Standardized, anonymous questionnaire including DSM-IV cannabis abuse criteria, Cannabis Abuse Screening Test (CAST), and Severity of Dependence Scale (SDS) was self-completed with paper and pencil in the selected classrooms. Data was analysed using classical psychometric theory, bivariate tests, and multinomial logistic regression analysis. Not responding to instruments' items (10.5–12.3%) was associated with reporting less frequent cannabis use. The instruments overlapped partially, with 16.1% of positives being positive on all three. SDS was more likely to identify younger users with lower frequency of use who thought habitual cannabis use posed a considerable problem. CAST positivity was associated with frequent cannabis use and related problems. It is feasible to use short psychometric scales in wide school surveys, but one must carefully choose the screening instrument, as different instruments identify different groups of users. These may correspond to different types of problematic cannabis use; however, measurement bias seems to play a role too. PMID:25969832

High-throughput in Vitro Data To Inform Prioritization of Ambient Water Monitoring and Testing for Endocrine Active Chemicals.

PubMed

Heiger-Bernays, Wendy J; Wegner, Susanna; Dix, David J

2018-01-16

The presence of industrial chemicals, consumer product chemicals, and pharmaceuticals is well documented in waters in the U.S. and globally. Most of these chemicals lack health-protective guidelines and many have been shown to have endocrine bioactivity. There is currently no systematic or national prioritization for monitoring waters for chemicals with endocrine disrupting activity. We propose ambient water bioactivity concentrations (AWBCs) generated from high throughput data as a health-based screen for endocrine bioactivity of chemicals in water. The U.S. EPA ToxCast program has screened over 1800 chemicals for estrogen receptor (ER) and androgen receptor (AR) pathway bioactivity. AWBCs are calculated for 110 ER and 212 AR bioactive chemicals using high throughput ToxCast data from in vitro screening assays and predictive pathway models, high-throughput toxicokinetic data, and data-driven assumptions about consumption of water. Chemical-specific AWBCs are compared with measured water concentrations in data sets from the greater Denver area, Minnesota lakes, and Oregon waters, demonstrating a framework for identifying endocrine bioactive chemicals. This approach can be used to screen potential cumulative endocrine activity in drinking water and to inform prioritization of future monitoring, chemical testing and pollution prevention efforts.

Application of the ToxMiner Database: Network Analysis of ...

EPA Pesticide Factsheets

The US EPA ToxCast program is using in vitro HTS (High-Throughput Screening) methods to profile and model bioactivity of environmental chemicals. The main goals of the ToxCast program are to generate predictive signatures of toxicity, and ultimately provide rapid and cost-effective alternatives to animal testing. The chemicals selected for Phase I are composed largely by a diverse set of pesticide active ingredients, which had sufficient supporting in vivo data included as part of their registration process with the EPA. Other miscellaneous chemicals of environmental concern were also included. Application of HTS to environmental toxicants is a novel approach to predictive toxicology and health risk assessment, and differs from what is required for drug efficacy screening in that biochemical interaction of environmental chemicals are sometimes weaker than that seen with drugs and their intended targets. Additionally, the chemical space covered by environmental chemicals is much broader compared to that of pharmaceuticals. The ToxMiner database has been created and added to the EPA’s ACToR (Aggregated Computational Toxicology Resource) chemical database. One purpose of the ToxMiner database is to link biological, metabolic and cellular pathway data to genes and in vitro assay data for the initial subset of chemicals screened in the ToxCast Phase I HTS assays. Also included in ToxMiner is human disease information, which correlates with ToxCast assays that tar

Application of the ToxMiner Database: Network Analysis ...

EPA Pesticide Factsheets

The US EPA ToxCast program is using in vitro HTS (High-Throughput Screening) methods to profile and model bioactivity of environmental chemicals. The main goals of the ToxCast program are to generate predictive signatures of toxicity, and ultimately provide rapid and cost-effective alternatives to animal testing. The chemicals selected for Phase I are composed largely by a diverse set of pesticide active ingredients, which had sufficient supporting in vivo data included as part of their registration process with the EPA. Other miscellaneous chemicals of environmental concern were also included. Application of HTS to environmental toxicants is a novel approach to predictive toxicology and health risk assessment, and differs from what is required for drug efficacy screening in that biochemical interaction of environmental chemicals are sometimes weaker than that seen with drugs and their intended targets. Additionally, the chemical space covered by environmental chemicals is much broader compared to that of pharmaceuticals. The ToxMiner database has been created and added to the EPA’s ACToR (Aggregated Computational Toxicology Resource) chemical database. One purpose of the ToxMiner database is to link biological, metabolic, and cellular pathway data to genes and in vitro assay data for the initial subset of chemicals screened in the ToxCast Phase I HTS assays. Also included in ToxMiner is human disease information, which correlates with ToxCast assays that ta

The U.S. EPA's ToxCast Chemical Screening Program and Predictive Modeling of Toxicity

EPA Science Inventory

The ToxCast program was developed by the U.S. EPA's National Center for Computational Toxicology to provide cost-effective high-throughput screening for the potential toxicity of thousands of chemicals. Phase I screened 309 compounds in over 500 assays to evaluate concentration-...

The ToxCast Pathway Database for Identifying Toxicity Signatures and Potential Modes of Action from Chemical Screening Data

EPA Science Inventory

The U.S. Environmental Protection Agency (EPA), through its ToxCast program, is developing predictive toxicity approaches that will use in vitro high-throughput screening (HTS), high-content screening (HCS) and toxicogenomic data to predict in vivo toxicity phenotypes. There are ...

An Integrated In Vitro and Computational Approach to Define the Exposure-Dose-Toxicity Relationships In High-Throughput Screens

EPA Science Inventory

Research efforts by the US Environmental Protection Agency have set out to develop alternative testing programs to prioritize limited testing resources toward chemicals that likely represent the greatest hazard to human health and the environment. Efforts such as EPA’s ToxCast r...

Informatics approach using metabolic reactivity classifiers to link in vitro to in vivo data in application to the ToxCast Phase I dataset

EPA Science Inventory

Strategic combinations and tiered application of alternative testing methods to replace or minimize the use of animal models is attracting much attention. With the advancement of high throughput screening (HTS) assays and legacy databases providing in vivo testing results, suffic...

Toxicity Screening of the ToxCast Phase II Chemical Library Using a Zebrafish Developmental Assay (SOT)

EPA Science Inventory

As part of the chemical screening and prioritization research program of the US EPA, the ToxCast Phase II chemicals were assessed using a vertebrate screen for developmental toxicity. Zebrafish embryos (Danio rerio) were exposed in 96-well plates from late-blastula stage (6hr pos...

Applications of high throughput screening to identify profiles of biological activity

EPA Science Inventory

ToxCast, the United States Environmental Protection Agency’s chemical prioritization research program, is developing methods for utilizing computational chemistry and bioactivity profiling to predict potential for toxicity and prioritize limited testing resources (www.epa.gov/toc...

Virtual Embryo: Systems Modeling in Developmental Toxicity

EPA Science Inventory

High-throughput screening (HTS) studies are providing a rich source of data that can be applied to chemical profiling to address sensitivity and specificity of molecular targets, biological pathways, cellular and developmental processes. EPA’s ToxCast project is testing 960 uniq...

New High Throughput Methods to Estimate Chemical ...

EPA Pesticide Factsheets

EPA has made many recent advances in high throughput bioactivity testing. However, concurrent advances in rapid, quantitative prediction of human and ecological exposures have been lacking, despite the clear importance of both measures for a risk-based approach to prioritizing and screening chemicals. A recent report by the National Research Council of the National Academies, Exposure Science in the 21st Century: A Vision and a Strategy (NRC 2012) laid out a number of applications in chemical evaluation of both toxicity and risk in critical need of quantitative exposure predictions, including screening and prioritization of chemicals for targeted toxicity testing, focused exposure assessments or monitoring studies, and quantification of population vulnerability. Despite these significant needs, for the majority of chemicals (e.g. non-pesticide environmental compounds) there are no or limited estimates of exposure. For example, exposure estimates exist for only 7% of the ToxCast Phase II chemical list. In addition, the data required for generating exposure estimates for large numbers of chemicals is severely lacking (Egeghy et al. 2012). This SAP reviewed the use of EPA's ExpoCast model to rapidly estimate potential chemical exposures for prioritization and screening purposes. The focus was on bounded chemical exposure values for people and the environment for the Endocrine Disruptor Screening Program (EDSP) Universe of Chemicals. In addition to exposure, the SAP

Applications of high throughput screening to identify profiles of biological activity relevant to carcinogenesis

EPA Science Inventory

ToxCast, the United States Environmental Protection Agency’s chemical prioritization research program, is developing methods for utilizing computational chemistry and bioactivity profiling to predict potential for toxicity and prioritize limited testing resources (www.epa.gov/toc...

Screening the ToxCast Phase II library for acute neurotoxicity using cortical neurons grown on multi-well microelectrode array (mwMEA) plates

EPA Science Inventory

We have used primary cortical neurons grown in multi-well microelectrode array (mwMEA) plates to screen the ToxCast Phase II library of 1055 unique compounds for the ability to cause acute neurotoxicity. Each compound was screened at a single high concentration of 40 µM...

Predicting Toxic and Therapeutic Mechanisms of the ToxCast Chemical Library by Phenotypic Screening (SOT)

EPA Science Inventory

Addressing safety aspects of drugs and environmental chemicals relies extensively on animal testing. However the quantity of chemicals needing assessment and challenges of species extrapolation require development of alternative approaches. Using 8 primary human cell systems (Bio...

Fun with High Throughput Toxicokinetics (CalEPA webinar)

EPA Science Inventory

Thousands of chemicals have been profiled by high-throughput screening (HTS) programs such as ToxCast and Tox21. These chemicals are tested in part because there are limited or no data on hazard, exposure, or toxicokinetics (TK). TK models aid in predicting tissue concentrations ...

Phenotypic screening of the ToxCast chemical library to classify toxic and therapeutic mechanisms

EPA Science Inventory

Addressing the safety aspects of drugs and environmental chemicals has historically been undertaken through animal testing. However, the quantity of chemicals in need of assessment and the challenges of species extrapolation require the development of alternative approaches. Our ...

HTTK: R Package for High-Throughput Toxicokinetics

EPA Science Inventory

Thousands of chemicals have been profiled by high-throughput screening programs such as ToxCast and Tox21; these chemicals are tested in part because most of them have limited or no data on hazard, exposure, or toxicokinetics. Toxicokinetic models aid in predicting tissue concent...

Evaluating ToxCast Assays for their Ability to Detect Genotoxicity

EPA Science Inventory

It has become evident over the past several decades, that though the standard battery of genotoxicity tests including bacterial and in vitro mammalian mutagenesis and in vitro and in vivo clastogenicity assays have been quite useful in screening out potent genotoxicants during th...

Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

NASA Astrophysics Data System (ADS)

Gabb, Timothy P.; Gayda, John; Garg, Anita

2007-01-01

Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, have been screened to compare their respective capabilities for impeller applications. Mar-M247LC has been selected for additional long term evaluations. Initial tests in helium indicate this inert environment may debit long term creep resistance of this alloy. Several wrought superalloys including Hastelloy® X, Inconel® 617, Inconel® 740, Nimonic® 263, Incoloy® MA956, and Haynes 230 are also being screened to compare their capabilities for duct applications. Haynes 230 has been selected for additional long term evaluations. Initial tests in helium are just underway for this alloy. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Therefore, long term microstructural stability is also being screened.

Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Gayda, john; Garg, Anita

2007-01-01

Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, have been screened to compare their respective capabilities for impeller applications. Mar-M247LC has been selected for additional long term evaluations. Initial tests in helium indicate this inert environment may debit long term creep resistance of this alloy. Several wrought superalloys including Hastelloy(Registered TradeMark) X, Inconel(Registered TradeMark) 617, Inconel(Registered TradeMark) 740, Nimonic(Registered TradeMark) 263, Incoloy(Registered TradeMark) MA956, and Haynes 230 are also being screened to compare their capabilities for duct applications. Haynes 230 has been selected for additional long term evaluations. Initial tests in helium are just underway for this alloy. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Therefore, long term microstructural stability is also being screened.

Identifying Structural Alerts Based on Zebrafish Developmental Morphological Toxicity (TDS)

EPA Science Inventory

Zebrafish constitute a powerful alternative animal model for chemical hazard evaluation. To provide an in vivo complement to high-throughput screening data from the ToxCast program, zebrafish developmental toxicity screens were conducted on the ToxCast Phase I (Padilla et al., 20...

tcpl: The ToxCast Pipeline for High-Throughput Screening Data

EPA Science Inventory

Motivation: The large and diverse high-throughput chemical screening efforts carried out by the US EPAToxCast program requires an efficient, transparent, and reproducible data pipeline.Summary: The tcpl R package and its associated MySQL database provide a generalized platform fo...

Use of High-Throughput Testing and Approaches for Evaluating Chemical Risk-Relevance to Humans

EPA Science Inventory

ToxCast is profiling the bioactivity of thousands of chemicals based on high-throughput screening (HTS) and computational models that integrate knowledge of biological systems and in vivo toxicities. Many of these assays probe signaling pathways and cellular processes critical to...

VIRTUAL EMBRYO: SYSTEMS MODELING IN DEVELOPMENTAL TOXICITY - Symposium: SOT 2012

EPA Science Inventory

High-throughput screening (HTS) studies are providing a rich source of data that can be applied to in vitro profiling of chemical compounds for biological activity and potential toxicity. Chemical profiling in ToxCast covered 965 drugs-chemicals in over 500 diverse assays testing...

Evaluation of food-relevant chemicals in the ToxCast high-throughput screening program

EPA Science Inventory

There are thousands of chemicals that are directly added to or come in contact with food, many of which have undergone little to no toxicological evaluation. The ToxCast high-throughput screening (HTS) program has evaluated over 1,800 chemicals in concentration-response across ~8...

EPA's ToxCast Program for Predicting Hazard and Prioritizing the Toxicity Testing of Environmental Chemicals

EPA Science Inventory

An alternative is to perform a set of relatively inexpensive and rapid high throughput screening (HTS) assays, derive signatures predictive of effects or modes of chemical toxicity from the HTS data, then use these predictions to prioritize chemicals for more detailed analysis. T...

Development of a Context-Rich Database of ToxCast Assay Annotations (SOT)

EPA Science Inventory

Major concerns exist for the large number of environmental chemicals which lack toxicity data. The tens of thousands of commercial substances in need of screening for potential human health effects would cost millions of dollars and several decades to test in traditional animal-b...

“httk”: EPA’s Tool for High Throughput Toxicokinetics (CompTox CoP)

EPA Science Inventory

Thousands of chemicals have been pro?led by high-throughput screening programs such as ToxCast and Tox21; these chemicals are tested in part because most of them have limited or no data on hazard, exposure, or toxicokinetics. Toxicokinetic models aid in predicting tissue concentr...

Biological profiling and dose-response modeling tools, characterizing uncertainty

EPA Science Inventory

Through its ToxCast project, the U.S. EPA has developed a battery of in vitro high throughput screening (HTS) assays designed to assess the potential toxicity of environmental chemicals. At present, over 1800 chemicals have been tested in up to 600 assays, yielding a large number...

Screening the ToxCast Phase 1 Chemical Library for Inhibition of Deiodinase Type 1 Activity.

PubMed

Hornung, Michael W; Korte, Joseph J; Olker, Jennifer H; Denny, Jeffrey S; Knutsen, Carsten; Hartig, Phillip C; Cardon, Mary C; Degitz, Sigmund J

2018-04-01

Thyroid hormone (TH) homeostasis is dependent upon coordination of multiple key events including iodide uptake, hormone synthesis, metabolism, and elimination, to maintain proper TH signaling. Deiodinase enzymes catalyze iodide release from THs to interconvert THs between active and inactive forms, and are integral to hormone metabolism. The activity of deiodinases has been identified as an important endpoint to include in the context of screening chemicals for TH disruption. To begin to address the potential for chemicals to inhibit these enzymes an adenovirus expression system was used to produce human deiodinase type 1 (DIO1) enzyme, established robust assay parameters for nonradioactive determination of iodide release by the Sandell-Kolthoff method, and employed a 96-well plate format for screening chemical libraries. An initial set of 18 chemicals was used to establish the assay, along with the known DIO1 inhibitor 6-propylthiouracil as a positive control. An additional 292 unique chemicals from the EPA's ToxCast phase 1_v2 chemical library were screened. Chemicals were initially screened at a single high concentration of 200 µM to identify potential DIO1 inhibitors. There were 50 chemicals, or 17% of the TCp1_v2 chemicals tested, that produced >20% inhibition of DIO1 activity. Eighteen of these inhibited DIO1 activity >50% and were further tested in concentration-response mode to determine IC50s. This work presents an initial effort toward identifying chemicals with potential for affecting THs via inhibition of deiodinases and sets the foundation for further testing of large chemical libraries against DIO1 and the other deiodinase enzymes involved in TH function.

Application of Targeted Functional Assays to Assess a Putative Vascular Disruption Developmental Toxicity Pathway Informed By ToxCast High-Throughput Screening Data

EPA Science Inventory

Chemical perturbation of vascular development is a putative toxicity pathway which may result in developmental toxicity. EPA’s high-throughput screening (HTS) ToxCast program contains assays which measure cellular signals and biological processes critical for blood vessel develop...

Extrapolation of mammalian-based ToxCast assay results to non-mammalian species to evaluate endocrine disruption

EPA Science Inventory

In vitro high-throughput screening (HTS) and in silico technologies have emerged as 21st century tools for chemical hazard identification. In 2007 the U.S. Environmental Protection Agency (EPA) launched the ToxCast Program, which has screened thousands of chemicals in hundreds of...

Cross-species extrapolation of mammalian-based ToxCast Data using Sequence Alignment to Predict Across Species Susceptibility (SeqAPASS)

EPA Science Inventory

In vitro high-throughput screening (HTS) and in silico technologies have emerged as 21st century tools for chemical hazard identification. In 2007 the U.S. Environmental Protection Agency (EPA) launched the ToxCast Program, which has screened thousands of chemicals in hundreds of...

Uncertainty Quantification in High Throughput Screening ...

EPA Pesticide Factsheets

Using uncertainty quantification, we aim to improve the quality of modeling data from high throughput screening assays for use in risk assessment. ToxCast is a large-scale screening program that analyzes thousands of chemicals using over 800 assays representing hundreds of biochemical and cellular processes, including endocrine disruption, cytotoxicity, and zebrafish development. Over 2.6 million concentration response curves are fit to models to extract parameters related to potency and efficacy. Models built on ToxCast results are being used to rank and prioritize the toxicological risk of tested chemicals and to predict the toxicity of tens of thousands of chemicals not yet tested in vivo. However, the data size also presents challenges. When fitting the data, the choice of models, model selection strategy, and hit call criteria must reflect the need for computational efficiency and robustness, requiring hard and somewhat arbitrary cutoffs. When coupled with unavoidable noise in the experimental concentration response data, these hard cutoffs cause uncertainty in model parameters and the hit call itself. The uncertainty will then propagate through all of the models built on the data. Left unquantified, this uncertainty makes it difficult to fully interpret the data for risk assessment. We used bootstrap resampling methods to quantify the uncertainty in fitting models to the concentration response data. Bootstrap resampling determines confidence intervals for

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asmussen, Robert M.; Lawter, Amanda R.; Stephenson, John R.

Washington River Protection Solutions (WRPS) is collecting relevant available data on waste forms for use as a supplemental immobilization technology, to provide the additional capacity needed to treat low-activity waste (LAW) in Hanford Site tanks and complete the tank waste cleanup mission in a timely and cost-effective manner. One candidate supplemental waste form, fabricated using a low-temperature process, is a cementitious grout called Cast Stone. Cast Stone has been under investigation for this application at Pacific Northwest National Laboratory (PNNL) since initial screening tests in FY13. This report is the culmination of work to lower the diffusivities of Tc andmore » I from Cast Stone using getters. Getters are compounds added to a system designed to selectively sequester a species of interest to provide increased stability to the species. The work contained within this report is related to waste form development and testing, and does not directly support the 2017 integrated disposal facility (IDF) performance assessment. However, this work contains valuable information which may be used in performance assessment maintenance past FY17, and in future waste form development. This report on performance characterization of Tc and I getters in Cast Stone fabricated with simulated LAW covers several areas of interest and major findings to WRPS: investigating performance of potassium metal sulfide (KMS-2-SS) and tin (II) apatite (Sn-A) as Tc getters when incorporated into Cast Stone; investigating performance of silver exchanged zeolite (Ag-Z) and argentite (Arg) as I getters when incorporated into Cast Stone; utilizing sequential addition of Tc and I getters to overcome any deleterious interactions between the getters in solution; determining, for the first time, Tc distribution within the cured Cast Stone and its evolution during leaching; and performing solid state characterization of getters and Cast Stone samples to support leach test findings and develop a mechanistic understanding of the processes that control Tc and I release into solution.« less

Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test Data--The Influence of Different Parameters in a Routine Clinical Microbiology Laboratory.

PubMed

Kohlmann, Rebekka; Gatermann, Sören G

2016-01-01

Many clinical microbiology laboratories report on cumulative antimicrobial susceptibility testing (cAST) data on a regular basis. Criteria for generation of cAST reports, however, are often obscure and inconsistent. Whereas the CLSI has published a guideline for analysis and presentation of cAST data, national guidelines directed at clinical microbiology laboratories are not available in Europe. Thus, we sought to describe the influence of different parameters in the process of cAST data analysis in the setting of a German routine clinical microbiology laboratory during 2 consecutive years. We developed various program scripts to assess the consequences ensuing from different algorithms for calculation of cumulative antibiograms from the data collected in our clinical microbiology laboratory in 2013 and 2014. One of the most pronounced effects was caused by exclusion of screening cultures for multi-drug resistant organisms which decreased the MRSA rate in some cases to one third. Dependent on the handling of duplicate isolates, i.e. isolates of the same species recovered from successive cultures on the same patient during the time period analyzed, we recorded differences in resistance rates of up to 5 percentage points for S. aureus, E. coli and K. pneumoniae and up to 10 percentage points for P. aeruginosa. Stratification by site of care and specimen type, testing of antimicrobials selectively on resistant isolates, change of interpretation rules and analysis at genus level instead of species level resulted in further changes of calculated antimicrobial resistance rates. The choice of parameters for cAST data analysis may have a substantial influence on calculated antimicrobial resistance rates. Consequently, comparability of cAST reports from different clinical microbiology laboratories may be limited. We suggest that laboratories communicate the strategy used for cAST data analysis as long as national guidelines for standardized cAST data analysis and reporting do not exist in Europe.

Endocrine Profiling and Prioritization of Environmental Chemicals Using ToxCast Data

PubMed Central

Reif, David M.; Martin, Matthew T.; Tan, Shirlee W.; Houck, Keith A.; Judson, Richard S.; Richard, Ann M.; Knudsen, Thomas B.; Dix, David J.; Kavlock, Robert J.

2010-01-01

Background The prioritization of chemicals for toxicity testing is a primary goal of the U.S. Environmental Protection Agency (EPA) ToxCast™ program. Phase I of ToxCast used a battery of 467 in vitro, high-throughput screening assays to assess 309 environmental chemicals. One important mode of action leading to toxicity is endocrine disruption, and the U.S. EPA’s Endocrine Disruptor Screening Program (EDSP) has been charged with screening pesticide chemicals and environmental contaminants for their potential to affect the endocrine systems of humans and wildlife. Objective The goal of this study was to develop a flexible method to facilitate the rational prioritization of chemicals for further evaluation and demonstrate its application as a candidate decision-support tool for EDSP. Methods Focusing on estrogen, androgen, and thyroid pathways, we defined putative endocrine profiles and derived a relative rank or score for the entire ToxCast library of 309 unique chemicals. Effects on other nuclear receptors and xenobiotic metabolizing enzymes were also considered, as were pertinent chemical descriptors and pathways relevant to endocrine-mediated signaling. Results Combining multiple data sources into an overall, weight-of-evidence Toxicological Priority Index (ToxPi) score for prioritizing further chemical testing resulted in more robust conclusions than any single data source taken alone. Conclusions Incorporating data from in vitro assays, chemical descriptors, and biological pathways in this prioritization schema provided a flexible, comprehensive visualization and ranking of each chemical’s potential endocrine activity. Importantly, ToxPi profiles provide a transparent visualization of the relative contribution of all information sources to an overall priority ranking. The method developed here is readily adaptable to diverse chemical prioritization tasks. PMID:20826373

Economic benefits of using adaptive predictive models of reproductive toxicity in the context of a tiered testing program

EPA Science Inventory

A predictive model of reproductive toxicity, as observed in rat multigeneration reproductive (MGR) studies, was previously developed using high throughput screening (HTS) data from 36 in vitro assays mapped to 8 genes or gene-sets from Phase I of USEPA ToxCast research program, t...

High Throughput PBTK: Evaluating EPA’s Open-Source Data and Tools for Dosimetry and Exposure Reconstruction

EPA Science Inventory

Thousands of chemicals have been profiled by high-throughput screening (HTS) programs such as ToxCast and Tox21; these chemicals are tested in part because most of them have limited or no data on hazard, exposure, or toxicokinetics (TK). While HTS generates in vitro bioactivity d...

Competitive allele-specific TaqMan PCR (Cast-PCR) is a sensitive, specific and fast method for BRAF V600 mutation detection in Melanoma patients

PubMed Central

Barbano, Raffaela; Pasculli, Barbara; Coco, Michelina; Fontana, Andrea; Copetti, Massimiliano; Rendina, Michelina; Valori, Vanna Maria; Graziano, Paolo; Maiello, Evaristo; Fazio, Vito Michele; Parrella, Paola

2015-01-01

BRAF codon 600 mutation testing of melanoma patients is mandatory for the choice of the most appropriate therapy in the clinical setting. Competitive allele specific TaqMan PCR (Cast-PCR) technology allows not only the selective amplification of minor alleles, but it also blocks the amplification of non-mutant allele. We genotyped codon 600 of the BRAF gene in 54 patients’ samples by Cast-PCR and bidirectional direct sequence analysis. All the mutations detected by sequencing were also identified by Cast-PCR. In addition, Cast-PCR assay detected four samples carrying mutations and was able to clearly identify two mutations of uncertain interpretation by Sanger sequencing. The limit of detection of Cast-PCR was evaluated by constructing dilution curves of BRAFV600E and BRAFV600K mutated clinical samples mixed with a not-mutated specimens. Both mutations could be detected until a 1:100 mutated/not mutated ratio. Cloning and sequencing of the clones was used to confirm mutations on representative discrepant cases. Cast PCR performances were not affected by intratumour heterogeneity, and less affected by melanin content. Our results indicate that Cast-PCR is a reliable diagnostic tool for the identification of melanoma patients as eligible to be treated with TKIs and might be implemented in the clinical setting as elective screening method. PMID:26690267

Quantitative Criteria to Screen for Cannabis Use Disorder.

PubMed

Casajuana, Cristina; López-Pelayo, Hugo; Miquel, Laia; Balcells-Oliveró, María Mercedes; Colom, Joan; Gual, Antoni

2018-06-27

The Standard Joint Unit (1 SJU = 7 mg of 9-Tetrahydrocannabinol) simplifies the exploration of risky patterns of cannabis use. This study proposes a preliminary quantitative cutoff criterion to screen for cannabis use disorder (CUD). Socio-demographical data and information on cannabis quantities, frequency of use, and risk for CUD (measured with the Cannabis Abuse Screening Test (CAST) of cannabis users recruited in Barcelona (from February 2015 to June 2016) were collected. CAST scores were categorized into low, moderate, and high risk for CUD, based on the SJU consumed and frequency. Receiver operating characteristic (ROC) analysis related daily SJU with CUD. Participants (n = 473) were on average 29 years old (SD = 10), men (77.1%), and single (74.6%). With an average of 4 joints per smoking day, 82.5% consumed cannabis almost every day. Risk for CUD (9.40% low, 23.72% moderate, 66.88% high) increased significantly with more frequency and quantities consumed. The ROC analyses suggest 1.2 SJU per day as a cutoff criterion to screen for at least moderate risk for CUD (sensitivity 69.4%, specificity 63.6%). Frequency and quantity should be considered when exploring cannabis risks. A 1 SJU per day is proposed as a preliminary quantitative-based criterion to screen users with at least a moderate risk for CUD. © 2018 S. Karger AG, Basel.

High-Throughput Screening and Quantitative Chemical Ranking for Sodium-Iodide Symporter Inhibitors in ToxCast Phase I Chemical Library.

PubMed

Wang, Jun; Hallinger, Daniel R; Murr, Ashley S; Buckalew, Angela R; Simmons, Steven O; Laws, Susan C; Stoker, Tammy E

2018-05-01

Thyroid uptake of iodide via the sodium-iodide symporter (NIS) is the first step in the biosynthesis of thyroid hormones that are critical for health and development in humans and wildlife. Despite having long been a known target of endocrine disrupting chemicals such as perchlorate, information regarding NIS inhibition activity is still unavailable for the vast majority of environmental chemicals. This study applied a previously validated high-throughput approach to screen for NIS inhibitors in the ToxCast phase I library, representing 293 important environmental chemicals. Here 310 blinded samples were screened in a tiered-approach using an initial single-concentration (100 μM) radioactive-iodide uptake (RAIU) assay, followed by 169 samples further evaluated in multi-concentration (0.001 μM-100 μM) testing in parallel RAIU and cell viability assays. A novel chemical ranking system that incorporates multi-concentration RAIU and cytotoxicity responses was also developed as a standardized method for chemical prioritization in current and future screenings. Representative chemical responses and thyroid effects of high-ranking chemicals are further discussed. This study significantly expands current knowledge of NIS inhibition potential in environmental chemicals and provides critical support to U.S. EPA's Endocrine Disruptor Screening Program (EDSP) initiative to expand coverage of thyroid molecular targets, as well as the development of thyroid adverse outcome pathways (AOPs).

Using the ToxMiner Database for Identifying Disease-Gene Associations in the ToxCast Dataset

EPA Science Inventory

The US EPA ToxCast program is using in vitro, high-throughput screening (HTS) to profile and model the bioactivity of environmental chemicals. The main goal of the ToxCast program is to generate predictive signatures of toxicity that ultimately provide rapid and cost-effective me...

Application of the ToxMiner Database: Network Analysis Linking the ToxCast Chemicals to Known Disease-Gene Associations

EPA Science Inventory

The US EPA ToxCast program is using in vitro HTS (High-Throughput Screening) methods to profile and model bioactivity of environmental chemicals. The main goals of the ToxCast program are to generate predictive signatures of toxicity, and ultimately provide rapid and cost-effecti...

ToxCast Assay Network (TCAN) Viewer: A Visualization Tool for High-throughput Assay Chemical Data (SOT)

EPA Science Inventory

USEPA’s ToxCast program has generated high-throughput bioactivity screening (HTS) data on thousands of chemicals. The ToxCast program has described and annotated the HTS assay battery with respect to assay design and target information (e.g., gene target). Recent stakeholder and ...

Tutorial Video Series: Using Stakeholder Outreach to Increase Usage of ToxCast Data (SETAC EU)

EPA Science Inventory

The limited amount of toxicity data on thousands of chemicals found in consumer products has led to the development of research endeavors such as the U.S. EPA’s Toxicity Forecaster (ToxCast). ToxCast uses high-throughput screening technology to evaluate thousands of chemicals for...

Species-specific predictive models of developmental toxicity using the ToxCast chemical library

EPA Science Inventory

EPA’s ToxCastTM project is profiling the in vitro bioactivity of chemicals to generate predictive models that correlate with observed in vivo toxicity. In vitro profiling methods are based on ToxCast data, consisting of over 600 high-throughput screening (HTS) and high-content sc...

Real-time stereographic display of volumetric datasets in radiology

NASA Astrophysics Data System (ADS)

Wang, Xiao Hui; Maitz, Glenn S.; Leader, J. K.; Good, Walter F.

2006-02-01

A workstation for testing the efficacy of stereographic displays for applications in radiology has been developed, and is currently being tested on lung CT exams acquired for lung cancer screening. The system exploits pre-staged rendering to achieve real-time dynamic display of slabs, where slab thickness, axial position, rendering method, brightness and contrast are interactively controlled by viewers. Stereo presentation is achieved by use of either frame-swapping images or cross-polarizing images. The system enables viewers to toggle between alternative renderings such as one using distance-weighted ray casting by maximum-intensity-projection, which is optimal for detection of small features in many cases, and ray casting by distance-weighted averaging, for characterizing features once detected. A reporting mechanism is provided which allows viewers to use a stereo cursor to measure and mark the 3D locations of specific features of interest, after which a pop-up dialog box appears for entering findings. The system's impact on performance is being tested on chest CT exams for lung cancer screening. Radiologists' subjective assessments have been solicited for other kinds of 3D exams (e.g., breast MRI) and their responses have been positive. Objective estimates of changes in performance and efficiency, however, must await the conclusion of our study.

Predicting hepatotoxicity using ToxCast in vitro bioactivity and ...

EPA Pesticide Factsheets

Background: The U.S. EPA ToxCastTM program is screening thousands of environmental chemicals for bioactivity using hundreds of high-throughput in vitro assays to build predictive models of toxicity. We represented chemicals based on bioactivity and chemical structure descriptors then used supervised machine learning to predict their hepatotoxic effects.Results: A set of 677 chemicals were represented by 711 in vitro bioactivity descriptors (from ToxCast assays), 4,376 chemical structure descriptors (from QikProp, OpenBabel, PADEL, and PubChem), and three hepatotoxicity categories (from animal studies). Hepatotoxicants were defined by rat liver histopathology observed after chronic chemical testing and grouped into hypertrophy (161), injury (101) and proliferative lesions (99). Classifiers were built using six machine learning algorithms: linear discriminant analysis (LDA), Naïve Bayes (NB), support vector classification (SVM), classification and regression trees (CART), k-nearest neighbors (KNN) and an ensemble of classifiers (ENSMB). Classifiers of hepatotoxicity were built using chemical structure, ToxCast bioactivity, and a hybrid representation. Predictive performance was evaluated using 10-fold cross-validation testing and in-loop, filter-based, feature subset selection. Hybrid classifiers had the best balanced accuracy for predicting hypertrophy (0.78±0.08), injury (0.73±0.10) and proliferative lesions (0.72±0.09). Though chemical and bioactivity class

A multisite blinded study for the detection of BRAF mutations in formalin-fixed, paraffin-embedded malignant melanoma

PubMed Central

Richter, Anna; Grieu, Fabienne; Carrello, Amerigo; Amanuel, Benhur; Namdarian, Kateh; Rynska, Aleksandra; Lucas, Amanda; Michael, Victoria; Bell, Anthony; Fox, Stephen B.; Hewitt, Chelsee A.; Do, Hongdo; McArthur, Grant A.; Wong, Stephen Q.; Dobrovic, Alexander; Iacopetta, Barry

2013-01-01

Melanoma patients with BRAF mutations respond to treatment with vemurafenib, thus creating a need for accurate testing of BRAF mutation status. We carried out a blinded study to evaluate various BRAF mutation testing methodologies in the clinical setting. Formalin-fixed, paraffin-embedded melanoma samples were macrodissected before screening for mutations using Sanger sequencing, single-strand conformation analysis (SSCA), high resolution melting analysis (HRM) and competitive allele-specific TaqMan® PCR (CAST-PCR). Concordance of 100% was observed between the Sanger sequencing, SSCA and HRM techniques. CAST-PCR gave rapid and accurate results for the common V600E and V600K mutations, however additional assays are required to detect rarer BRAF mutation types found in 3–4% of melanomas. HRM and SSCA followed by Sanger sequencing are effective two-step strategies for the detection of BRAF mutations in the clinical setting. CAST-PCR was useful for samples with low tumour purity and may also be a cost-effective and robust method for routine diagnostics. PMID:23584600

Investigation of Advanced Processed Single-Crystal Turbine Blade Alloys

NASA Technical Reports Server (NTRS)

Peters, B. J.; Biondo, C. M.; DeLuca, D. P.

1995-01-01

This investigation studied the influence of thermal processing and microstructure on the mechanical properties of the single-crystal, nickel-based superalloys PWA 1482 and PWA 1484. The objective of the program was to develop an improved single-crystal turbine blade alloy that is specifically tailored for use in hydrogen fueled rocket engine turbopumps. High-gradient casting, hot isostatic pressing (HIP), and alternate heat treatment (HT) processing parameters were developed to produce pore-free, eutectic-free microstructures with different (gamma)' precipitate morphologies. Test materials were cast in high thermal gradient solidification (greater than 30 C/cm (137 F/in.)) casting furnaces for reduced dendrite arm spacing, improved chemical homogeneity, and reduced interdendritic pore size. The HIP processing was conducted in 40 cm (15.7 in.) diameter production furnaces using a set of parameters selected from a trial matrix study. Metallography was conducted on test samples taken from each respective trial run to characterize the as-HIP microstructure. Post-HIP alternate HT processes were developed for each of the two alloys. The goal of the alternate HT processing was to fully solution the eutectic gamma/(gamma)' phase islands and to develop a series of modified (gamma)' morphologies for subsequent characterization testing. This was accomplished by slow cooling through the (gamma)' solvus at controlled rates to precipitate volume fractions of large (gamma)'. Post-solution alternate HT parameters were established for each alloy providing additional volume fractions of finer precipitates. Screening tests included tensile, high-cycle fatigue (HCF), smooth and notched low-cycle fatigue (LCF), creep, and fatigue crack growth evaluations performed in air and high pressure (34.5 MPa (5 ksi)) hydrogen at room and elevated temperature. Under the most severe embrittling conditions (HCF and smooth and notched LCF in 34.5 MPa (5 ksi) hydrogen at 20 C (68 F), screening test results showed increases in fatigue life typically on the order of 1OX, when compared to the current Space Shuttle Main Engine (SSME) Alternate Turbopump (AT) blade alloy (PWA 1480).

Application of the ToxMiner Database: Network Analysis of Linkage between ToxCast Phase I Chemicals and Thyroid Related Disease Outcomes

EPA Science Inventory

The US EPA ToxCast program is using in vitro HTS (High-Throughput Screening) methods to profile and model bioactivity of environmental chemicals. The main goals of the ToxCast program are to generate predictive signatures of toxicity, and ultimately provide rapid and cost-effecti...

Analysis of ToxCast data for food-relevant compounds by comparison with in vivo data using the RISK21 approach

EPA Science Inventory

The ToxCast program has generated a wealth of in vitro high throughput screening data, and best approaches for the interpretation and use of these data remain undetermined. We present case studies comparing the ToxCast and in vivo toxicity data for two food contact substances us...

20180312 - Profiling the ToxCast library with a pluripotent human (H9) embryonic stem cell assay (SOT)

EPA Science Inventory

The Stemina devTOX quickPredict platform (STM) is a human pluripotent H9 stem cell-based assay that predicts developmental toxicants. Using the STM model, we screened 1065 ToxCast chemicals and entered the data into the ToxCast data analysis pipeline. Model performance was 83.3% ...

Development and Validation of a Computational Model for Androgen Receptor Activity

PubMed Central

2016-01-01

Testing thousands of chemicals to identify potential androgen receptor (AR) agonists or antagonists would cost millions of dollars and take decades to complete using current validated methods. High-throughput in vitro screening (HTS) and computational toxicology approaches can more rapidly and inexpensively identify potential androgen-active chemicals. We integrated 11 HTS ToxCast/Tox21 in vitro assays into a computational network model to distinguish true AR pathway activity from technology-specific assay interference. The in vitro HTS assays probed perturbations of the AR pathway at multiple points (receptor binding, coregulator recruitment, gene transcription, and protein production) and multiple cell types. Confirmatory in vitro antagonist assay data and cytotoxicity information were used as additional flags for potential nonspecific activity. Validating such alternative testing strategies requires high-quality reference data. We compiled 158 putative androgen-active and -inactive chemicals from a combination of international test method validation efforts and semiautomated systematic literature reviews. Detailed in vitro assay information and results were compiled into a single database using a standardized ontology. Reference chemical concentrations that activated or inhibited AR pathway activity were identified to establish a range of potencies with reproducible reference chemical results. Comparison with existing Tier 1 AR binding data from the U.S. EPA Endocrine Disruptor Screening Program revealed that the model identified binders at relevant test concentrations (<100 μM) and was more sensitive to antagonist activity. The AR pathway model based on the ToxCast/Tox21 assays had balanced accuracies of 95.2% for agonist (n = 29) and 97.5% for antagonist (n = 28) reference chemicals. Out of 1855 chemicals screened in the AR pathway model, 220 chemicals demonstrated AR agonist or antagonist activity and an additional 174 chemicals were predicted to have potential weak AR pathway activity. PMID:27933809

Incorporating High-Throughput Exposure Predictions With Dosimetry-Adjusted In Vitro Bioactivity to Inform Chemical Toxicity Testing

PubMed Central

Wetmore, Barbara A.; Wambaugh, John F.; Allen, Brittany; Ferguson, Stephen S.; Sochaski, Mark A.; Setzer, R. Woodrow; Houck, Keith A.; Strope, Cory L.; Cantwell, Katherine; Judson, Richard S.; LeCluyse, Edward; Clewell, Harvey J.; Thomas, Russell S.; Andersen, Melvin E.

2015-01-01

We previously integrated dosimetry and exposure with high-throughput screening (HTS) to enhance the utility of ToxCast HTS data by translating in vitro bioactivity concentrations to oral equivalent doses (OEDs) required to achieve these levels internally. These OEDs were compared against regulatory exposure estimates, providing an activity-to-exposure ratio (AER) useful for a risk-based ranking strategy. As ToxCast efforts expand (ie, Phase II) beyond food-use pesticides toward a wider chemical domain that lacks exposure and toxicity information, prediction tools become increasingly important. In this study, in vitro hepatic clearance and plasma protein binding were measured to estimate OEDs for a subset of Phase II chemicals. OEDs were compared against high-throughput (HT) exposure predictions generated using probabilistic modeling and Bayesian approaches generated by the U.S. Environmental Protection Agency (EPA) ExpoCast program. This approach incorporated chemical-specific use and national production volume data with biomonitoring data to inform the exposure predictions. This HT exposure modeling approach provided predictions for all Phase II chemicals assessed in this study whereas estimates from regulatory sources were available for only 7% of chemicals. Of the 163 chemicals assessed in this study, 3 or 13 chemicals possessed AERs < 1 or < 100, respectively. Diverse bioactivities across a range of assays and concentrations were also noted across the wider chemical space surveyed. The availability of HT exposure estimation and bioactivity screening tools provides an opportunity to incorporate a risk-based strategy for use in testing prioritization. PMID:26251325

Data from Tiered High-Throughput Screening Approach to Identify Thyroperoxidase Inhibitors within the ToxCast Phase I and II Chemical Libraries

EPA Pesticide Factsheets

High-throughput screening for potential thyroid-disrupting chemicals requires a system of assays to capture multiple molecular-initiating events (MIEs) that converge on perturbed thyroid hormone (TH) homeostasis. Screening for MIEs specific to TH-disrupting pathways is limited in the U.S. Environmental Protection Agency ToxCast screening assay portfolio. To fill 1 critical screening gap, the Amplex UltraRed-thyroperoxidase (AUR-TPO) assay was developed to identify chemicals that inhibit TPO, as decreased TPO activity reduces TH synthesis. The ToxCast phase I and II chemical libraries, comprised of 1074 unique chemicals, were initially screened using a single, high concentration to identify potential TPO inhibitors. Chemicals positive in the single-concentration screen were retested in concentration-response. Due to high false-positive rates typically observed with loss-of-signal assays such as AUR-TPO, we also employed 2 additional assays in parallel to identify possible sources of nonspecific assay signal loss, enabling stratification of roughly 300 putative TPO inhibitors based upon selective AUR-TPO activity. A cell-free luciferase inhibition assay was used to identify nonspecific enzyme inhibition among the putative TPO inhibitors, and a cytotoxicity assay using a human cell line was used to estimate the cellular tolerance limit. Additionally, the TPO inhibition activities of 150 chemicals were compared between the AUR-TPO and an orthogonal peroxidase oxidat

Assessment of ToxCast Phase II for Mitochondrial Liabilities Using a High-Throughput Respirometric Assay

PubMed Central

Wills, Lauren P.; Beeson, Gyda C.; Hoover, Douglas B.; Schnellmann, Rick G.; Beeson, Craig C.

2015-01-01

Previous high-throughput screens to identify mitochondrial toxicants used immortalized cell lines and focused on changes in mitochondrial membrane potential, which may not be sufficient and do not identify different types of mitochondrial dysfunction. Primary cultures of renal proximal tubule cells (RPTC) were examined with the Seahorse Extracellular Flux Analyzer to screen 676 compounds (5 μM; 1 h) from the ToxCast Phase II library for mitochondrial toxicants. Of the 676 compounds, 19 were classified as cytotoxicants, 376 were electron transport chain (ETC) inhibitors, and 5 were uncouplers. The remaining 276 compounds were examined after a 5-h exposure to identify slower acting mitochondrial toxicants. This experiment identified 3 cytotoxicants, 110 ETC inhibitors, and 163 compounds with no effect. A subset of the ToxCast Phase II library was also examined in immortalized human renal cells (HK2) to determine differences in susceptibility to mitochondrial toxicity. Of the 131 RPTC ETC inhibitors tested, only 14 were ETC inhibitors in HK2 cells. Of the 5 RPTC uncouplers, 1 compound was an uncoupler in HK2 cells. These results demonstrate that 73% (491/676) of the compounds in the ToxCast Phase II library compounds exhibit RPTC mitochondrial toxicity, overwhelmingly ETC inhibition. In contrast, renal HK2 cells are markedly less sensitive and only identified 6% of the compounds as mitochondrial toxicants. We suggest caution is needed when studying mitochondrial toxicity in immortalized cell lines. This information will provide mechanisms and chemical-based criteria for assessing and predicting mitochondrial liabilities of new drugs, consumer products, and environmental agents. PMID:25926417

Using the ToxMiner Database for a Network Analysis of Linkage between ToxCast Phase I Chemicals and Thyroid Related Disease Outcomes

EPA Science Inventory

The US EPA ToxCast program is using in vitro, high-throughput screening (HTS) to profile and model the bioactivity of environmental chemicals. The main goal of the ToxCast program is to generate predictive signatures of toxicity that ultimately provide rapid and cost-effective me...

Application of ToxCast High-Throughput Screening and ...

EPA Pesticide Factsheets

Slide presentation at the SETAC annual meeting on High-Throughput Screening and Modeling Approaches to Identify Steroidogenesis Distruptors Slide presentation at the SETAC annual meeting on High-Throughput Screening and Modeling Approaches to Identify Steroidogenssis Distruptors

An “EAR” on environmental surveillance and monitoring: A case study on the use of Exposure–Activity Ratios (EARs) to prioritize sites, chemicals, and bioactivities of concern in Great Lakes waters

USGS Publications Warehouse

Blackwell, Brett R.; Ankley, Gerald T.; Corsi, Steven; DeCicco, Laura; Houck, Kieth A.; Judson, Richard S.; Li, Shibin; Martin, Matthew T.; Murphy, Elizabeth; Schroeder, Anthony L.; Smith, Edwin R.; Swintek, Joe; Villeneuve, Daniel L.

2017-01-01

Current environmental monitoring approaches focus primarily on chemical occurrence. However, based on concentration alone, it can be difficult to identify which compounds may be of toxicological concern and should be prioritized for further monitoring, in-depth testing, or management. This can be problematic because toxicological characterization is lacking for many emerging contaminants. New sources of high-throughput screening (HTS) data, such as the ToxCast database, which contains information for over 9000 compounds screened through up to 1100 bioassays, are now available. Integrated analysis of chemical occurrence data with HTS data offers new opportunities to prioritize chemicals, sites, or biological effects for further investigation based on concentrations detected in the environment linked to relative potencies in pathway-based bioassays. As a case study, chemical occurrence data from a 2012 study in the Great Lakes Basin along with the ToxCast effects database were used to calculate exposure–activity ratios (EARs) as a prioritization tool. Technical considerations of data processing and use of the ToxCast database are presented and discussed. EAR prioritization identified multiple sites, biological pathways, and chemicals that warrant further investigation. Prioritized bioactivities from the EAR analysis were linked to discrete adverse outcome pathways to identify potential adverse outcomes and biomarkers for use in subsequent monitoring efforts.

tcpl: the ToxCast pipeline for high-throughput screening data.

PubMed

Filer, Dayne L; Kothiya, Parth; Setzer, R Woodrow; Judson, Richard S; Martin, Matthew T

2017-02-15

Large high-throughput screening (HTS) efforts are widely used in drug development and chemical toxicity screening. Wide use and integration of these data can benefit from an efficient, transparent and reproducible data pipeline. Summary: The tcpl R package and its associated MySQL database provide a generalized platform for efficiently storing, normalizing and dose-response modeling of large high-throughput and high-content chemical screening data. The novel dose-response modeling algorithm has been tested against millions of diverse dose-response series, and robustly fits data with outliers and cytotoxicity-related signal loss. tcpl is freely available on the Comprehensive R Archive Network under the GPL-2 license. martin.matt@epa.gov. Published by Oxford University Press 2016. This work is written by US Government employees and is in the public domain in the US.

High Throughput Transcriptomics: From screening to pathways

EPA Science Inventory

The EPA ToxCast effort has screened thousands of chemicals across hundreds of high-throughput in vitro screening assays. The project is now leveraging high-throughput transcriptomic (HTTr) technologies to substantially expand its coverage of biological pathways. The first HTTr sc...

ToxCast Data Expands Universe of Chemical-Gene Interactions (SOT)

EPA Science Inventory

Characterizing the effects of chemicals in biological systems is often summarized by chemical-gene interactions, which have sparse coverage in literature. The ToxCast chemical screening program has produced bioactivity data for nearly 2000 chemicals and over 450 gene targets. Thi...

20170312 - Adverse Outcome Pathway (AOP) framework for ...

EPA Pesticide Factsheets

Vascular development commences with de novo assembly of a primary capillary plexus (vasculogenesis) followed by its expansion (angiogenesis) and maturation (angio-adaptation) into a hierarchical system of arteries and veins. These processes are tightly regulated by genetic signals and environmental factors linked to morphogenesis and microphysiology. Gestational exposure to some chemicals disrupts vascular development leading to adverse outcomes. To broadly assess consequences of gestational toxicant exposure on vascular development, an Adverse Outcome Pathway (AOP) framework was constructed that integrates data from ToxCast high-throughput screening (HTS) assays with pathway-level information from the literature and public databases. The AOP-based model resolved the ToxCast library (1065 compounds) into a matrix based on several dozen molecular functions critical for developmental angiogenesis. A sample of 38 ToxCast chemicals selected across the matrix tested model performance. Putative vascular disrupting chemical (pVDC) bioactivity was assessed by multiple laboratories utilizing diverse angiogenesis assays, including: transgenic zebrafish, complex human cell co-cultures, engineered microscale systems, and human-synthetic models. The ToxCast pVDC signature predicted vascular disruption in a manner that was chemical-specific and assay-dependent. An AOP for developmental vascular toxicity was constructed that focuses on inhibition of VEGF receptor (VEGFR2). Thi

Adverse Outcome Pathway (AOP) framework for embryonic ...

EPA Pesticide Factsheets

Vascular development commences with de novo assembly of a primary capillary plexus (vasculogenesis) followed by its expansion (angiogenesis) and maturation (angio-adaptation) into a hierarchical system of arteries and veins. These processes are tightly regulated by genetic signals and environmental factors linked to morphogenesis and microphysiology. Gestational exposure to some chemicals disrupts vascular development leading to adverse outcomes. To broadly assess consequences of gestational toxicant exposure on vascular development, an Adverse Outcome Pathway (AOP) framework was constructed that integrates data from ToxCast high-throughput screening (HTS) assays with pathway-level information from the literature and public databases. The AOP-based model resolved the ToxCast library (1065 compounds) into a matrix based on several dozen molecular functions critical for developmental angiogenesis. A sample of 38 ToxCast chemicals selected across the matrix tested model performance. Putative vascular disrupting chemical (pVDC) bioactivity was assessed by multiple laboratories utilizing diverse angiogenesis assays, including: transgenic zebrafish, complex human cell co-cultures, engineered microscale systems, and human-synthetic models. The ToxCast pVDC signature predicted vascular disruption in a manner that was chemical-specific and assay-dependent. An AOP for developmental vascular toxicity was constructed that focuses on inhibition of VEGF receptor (VEGFR2). Thi

Tensile and Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Gayda, John

2006-01-01

This paper represents a status report documenting the work on creep of superalloys performed under Project Prometheus. Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, are being screened to compare their respective capabilities for impeller applications. Several wrought superalloys including Hastelloy X, (Haynes International, Inc., Kokomo, IN), Inconel 617, Inconel 740, Nimonic 263, and Incoloy MA956 (Special Metals Corporation, Huntington, WV) are also being screened to compare their capabilities for duct applications. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Conventional tensile and creep tests were performed at temperatures up to 1200 K on specimens extracted from the materials. Initial microstructure evaluations were also undertaken.

20180311 - High Throughput Transcriptomics: From screening to pathways (SOT 2018)

EPA Science Inventory

The EPA ToxCast effort has screened thousands of chemicals across hundreds of high-throughput in vitro screening assays. The project is now leveraging high-throughput transcriptomic (HTTr) technologies to substantially expand its coverage of biological pathways. The first HTTr sc...

Predicting hepatotoxicity using ToxCast in vitro bioactivity and chemical structure

EPA Science Inventory

Background: The U.S. EPA ToxCastTM program is screening thousands of environmental chemicals for bioactivity using hundreds of high-throughput in vitro assays to build predictive models of toxicity. We represented chemicals based on bioactivity and chemical structure descriptors ...

Modeling limb-bud dysmorphogenesis in a predictive virtual embryo model

EPA Science Inventory

ToxCast is profiling the bioactivity of thousands of chemicals based on high-throughput screening (HTS) and computational methods that integrate knowledge of biological systems and in vivo toxicities (www.epa.gov/ncct/toxcast/). Many ToxCast assays assess signaling pathways and c...

Metabolism Retrofit Strategies for ToxCast Assays (BOSC)

EPA Science Inventory

The EPA’s ToxCast program utilizes a wide variety of high-throughput screening assays (HTS) to assess chemical perturbations of molecular and cellular endpoints. A limitation of many HTS assays used for toxicity assessment is the lack of xenobiotic metabolism (XM) which precludes...

Tiered High-Throughput Screening Approach to Identify Thyroperoxidase Inhibitors Within the ToxCast Phase I and II Chemical Libraries

PubMed Central

Watt, Eric D.; Hornung, Michael W.; Hedge, Joan M.; Judson, Richard S.; Crofton, Kevin M.; Houck, Keith A.; Simmons, Steven O.

2016-01-01

High-throughput screening for potential thyroid-disrupting chemicals requires a system of assays to capture multiple molecular-initiating events (MIEs) that converge on perturbed thyroid hormone (TH) homeostasis. Screening for MIEs specific to TH-disrupting pathways is limited in the U.S. Environmental Protection Agency ToxCast screening assay portfolio. To fill 1 critical screening gap, the Amplex UltraRed-thyroperoxidase (AUR-TPO) assay was developed to identify chemicals that inhibit TPO, as decreased TPO activity reduces TH synthesis. The ToxCast phase I and II chemical libraries, comprised of 1074 unique chemicals, were initially screened using a single, high concentration to identify potential TPO inhibitors. Chemicals positive in the single-concentration screen were retested in concentration-response. Due to high false-positive rates typically observed with loss-of-signal assays such as AUR-TPO, we also employed 2 additional assays in parallel to identify possible sources of nonspecific assay signal loss, enabling stratification of roughly 300 putative TPO inhibitors based upon selective AUR-TPO activity. A cell-free luciferase inhibition assay was used to identify nonspecific enzyme inhibition among the putative TPO inhibitors, and a cytotoxicity assay using a human cell line was used to estimate the cellular tolerance limit. Additionally, the TPO inhibition activities of 150 chemicals were compared between the AUR-TPO and an orthogonal peroxidase oxidation assay using guaiacol as a substrate to confirm the activity profiles of putative TPO inhibitors. This effort represents the most extensive TPO inhibition screening campaign to date and illustrates a tiered screening approach that focuses resources, maximizes assay throughput, and reduces animal use. PMID:26884060

Integrating Biological and Chemical Data for Hepatotoxicity Prediction (SOT)

EPA Science Inventory

The U.S. EPA ToxCastTM program is screening thousands of environmental chemicals for bioactivity using hundreds of high-throughput in vitro assays to build predictive models of toxicity. A set of 677 chemicals were represented by 711 bioactivity descriptors (from ToxCast assays),...

High-Throughput Models for Exposure-Based Chemical Prioritization in the ExpoCast Project

EPA Science Inventory

The United States Environmental Protection Agency (U.S. EPA) must characterize potential risks to human health and the environment associated with manufacture and use of thousands of chemicals. High-throughput screening (HTS) for biological activity allows the ToxCast research pr...

High Throughput Genotoxicity Profiling of the US EPA ToxCast Chemical Library

EPA Science Inventory

A key aim of the ToxCast project is to investigate modern molecular and genetic high content and high throughput screening (HTS) assays, along with various computational tools to supplement and perhaps replace traditional assays for evaluating chemical toxicity. Genotoxicity is a...

Differentiating Pathway-Specific From Nonspecific Effects in High-Throughput Toxicity Data: A Foundation for Prioritizing Adverse Outcome Pathway Development.

PubMed

Fay, Kellie A; Villeneuve, Daniel L; Swintek, Joe; Edwards, Stephen W; Nelms, Mark D; Blackwell, Brett R; Ankley, Gerald T

2018-06-01

The U.S. Environmental Protection Agency's ToxCast program has screened thousands of chemicals for biological activity, primarily using high-throughput in vitro bioassays. Adverse outcome pathways (AOPs) offer a means to link pathway-specific biological activities with potential apical effects relevant to risk assessors. Thus, efforts are underway to develop AOPs relevant to pathway-specific perturbations detected in ToxCast assays. Previous work identified a "cytotoxic burst" (CTB) phenomenon wherein large numbers of the ToxCast assays begin to respond at or near test chemical concentrations that elicit cytotoxicity, and a statistical approach to defining the bounds of the CTB was developed. To focus AOP development on the molecular targets corresponding to ToxCast assays indicating pathway-specific effects, we conducted a meta-analysis to identify which assays most frequently respond at concentrations below the CTB. A preliminary list of potentially important, target-specific assays was determined by ranking assays by the fraction of chemical hits below the CTB compared with the number of chemicals tested. Additional priority assays were identified using a diagnostic-odds-ratio approach which gives greater ranking to assays with high specificity but low responsivity. Combined, the two prioritization methods identified several novel targets (e.g., peripheral benzodiazepine and progesterone receptors) to prioritize for AOP development, and affirmed the importance of a number of existing AOPs aligned with ToxCast targets (e.g., thyroperoxidase, estrogen receptor, aromatase). The prioritization approaches did not appear to be influenced by inter-assay differences in chemical bioavailability. Furthermore, the outcomes were robust based on a variety of different parameters used to define the CTB.

Predictive Modeling of Apical Toxicity Endpoints Using Data ...

EPA Pesticide Factsheets

The US EPA and other regulatory agencies face a daunting challenge of evaluating potential toxicity for tens of thousands of environmental chemicals about which little is currently known. The EPA’s ToxCast program is testing a novel approach to this problem by screening compounds using a variety of in vitro assays and using the results to prioritize chemicals for further, more detailed testing. Phase I of ToxCast is testing 320 chemicals (mainly pesticide active ingredients) against ~400 cell-based and biochemical assays. In order to anchor these studies, we are using in vivo guideline study data for subchronic, chronic, cancer, reproductive and developmental endpoints. This data is compiled in the EPA toxicity reference database, ToxRefDB. The main goal of ToxCast is the discovery and validation of “signatures” linking in vitro assay data to in vivo toxicity endpoints. These signatures will be collections of assays that are correlated with particular endpoints. These assay collections should also help define molecular-and cellular-level mechanisms of toxicity. This talk will discuss our strategy to use a combination of statistical and machine learning methods, coupled with biochemical network or systems biology approaches. Our initial examples will focus signatures for endpoints from 2 year rodent cancer bioassays. Most of the data we have analyzed is in dose or concentration response series, so to effectively use this data we have developed novel appro

Chemical-Gene Interactions from ToxCast Bioactivity Data Expands Universe of Literature Network-Based Associations (SOT)

EPA Science Inventory

Characterizing the effects of chemicals in biological systems is often summarized by chemical-gene interactions, which have sparse coverage in the literature. The ToxCast chemical screening program has produced bioactivity data for nearly 2000 chemicals and over 450 gene targets....

Application of ToxCast to evaluate potential biological effects from organic contaminants in Great Lakes tributaries

EPA Science Inventory

With the development of “high throughput” in-vitro biological assays, screening-level information on potential adverse biological effects is available for a rapidly increasing number of chemicals. The U.S. EPA ToxCast program has now evaluated several thousand chemica...

Tox21 and ToxCast Chemical Landscapes: Laying the Foundation for 21st Century Toxicology

EPA Science Inventory

The U.S. Environmental Protection Agency’s ToxCast project and the related, multi-Agency Tox21 project are employing high-throughput technologies to screen hundreds to thousands of chemicals in hundreds of assays, probing a wide diversity of biological targets, pathways and mecha...

The US EPAs ToxCast Program for the Prioritization and Prediction of Environmental Chemical Toxicity

EPA Science Inventory

To meet the need for evaluating large numbers of chemicals for potential toxicity, the U.S. Environmental Protection Agency has initiated a research project call ToxCast that makes use of recent advances in molecular biology and high-throughput screening. These technologies have ...

ToxMiner: Relating ToxCast bioactivity profiles to phenotypic outcomes

EPA Science Inventory

One aim of the U.S. EPA ToxCast program is to develop predictive models that use in vitro assays to screen and prioritize environmental chemicals for further evaluation of potential toxicity. One aspect of this task is the compilation, quality control and analysis of large amount...

Design of experiments to optimize an in vitro cast to predict human nasal drug deposition.

PubMed

Shah, Samir A; Dickens, Colin J; Ward, David J; Banaszek, Anna A; George, Chris; Horodnik, Walter

2014-02-01

Previous studies showed nasal spray in vitro tests cannot predict in vivo deposition, pharmacokinetics, or pharmacodynamics. This challenge makes it difficult to assess deposition achieved with new technologies delivering to the therapeutically beneficial posterior nasal cavity. In this study, we determined best parameters for using a regionally divided nasal cast to predict deposition. Our study used a model suspension and a design of experiments to produce repeatable deposition results that mimic nasal deposition patterns of nasal suspensions from the literature. The seven-section (the nozzle locator, nasal vestibule, front turbinate, rear turbinate, olfactory region, nasopharynx, and throat filter) nylon nasal cast was based on computed tomography images of healthy humans. It was coated with a glycerol/Brij-35 solution to mimic mucus. After assembling and orienting, airflow was applied and nasal spray containing a model suspension was sprayed. After disassembling the cast, drug depositing in each section was assayed by HPLC. The success criteria for optimal settings were based on nine in vivo studies in the literature. The design of experiments included exploratory and half factorial screening experiments to identify variables affecting deposition (angles, airflow, and airflow time), optimization experiments, and then repeatability and reproducibility experiments. We found tilt angle and airflow time after actuation affected deposition the most. The optimized settings were flow rate of 16 L/min, postactuation flow time of 12 sec, a tilt angle of 23°, nozzle angles of 0°, and actuation speed of 5 cm/sec. Neither cast nor operator caused significant variation of results. We determined cast parameters to produce results resembling suspension nasal sprays in the literature. The results were repeatable and unaffected by operator or cast. These nasal spray parameters could be used to assess deposition from new devices or formulations. For human deposition studies using radiolabeled formulations, this cast could show that radiolabel deposition represents drug deposition. Our methods could also be used to optimize settings for other casts.

DUMPING COOLED MOLDS FROM THE SHAKE OUT RAILS ONTO A ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DUMPING COOLED MOLDS FROM THE SHAKE OUT RAILS ONTO A VIBRATING CONVEYOR WHICH TRANSPORTS CASTINGS AND SAND TO A SEPARATION SCREEN WHICH SIFTS SAND ONTO BELT CONVEYORS BELOW THAT CARRY IT PAST SWITCH-ACTIVATED WATER INJECTORS TO SIMILAR SWITCH-ACTIVATED FRESH SAND ADDERS BEFORE TRANSPORTING IT TO THE SAND STORAGE BIN WHILE CASTINGS ARE EITHER MANUALLY OR SMALL CRANE LIFTED TO DEGATING AREAS. - Southern Ductile Casting Company, Centerville Foundry, 101 Airport Road, Centreville, Bibb County, AL

In vitro screening of environmental chemicals for targeted testing prioritization: the ToxCast project.

PubMed

Judson, Richard S; Houck, Keith A; Kavlock, Robert J; Knudsen, Thomas B; Martin, Matthew T; Mortensen, Holly M; Reif, David M; Rotroff, Daniel M; Shah, Imran; Richard, Ann M; Dix, David J

2010-04-01

Chemical toxicity testing is being transformed by advances in biology and computer modeling, concerns over animal use, and the thousands of environmental chemicals lacking toxicity data. The U.S. Environmental Protection Agency's ToxCast program aims to address these concerns by screening and prioritizing chemicals for potential human toxicity using in vitro assays and in silico approaches. This project aims to evaluate the use of in vitro assays for understanding the types of molecular and pathway perturbations caused by environmental chemicals and to build initial prioritization models of in vivo toxicity. We tested 309 mostly pesticide active chemicals in 467 assays across nine technologies, including high-throughput cell-free assays and cell-based assays, in multiple human primary cells and cell lines plus rat primary hepatocytes. Both individual and composite scores for effects on genes and pathways were analyzed. Chemicals displayed a broad spectrum of activity at the molecular and pathway levels. We saw many expected interactions, including endocrine and xenobiotic metabolism enzyme activity. Chemicals ranged in promiscuity across pathways, from no activity to affecting dozens of pathways. We found a statistically significant inverse association between the number of pathways perturbed by a chemical at low in vitro concentrations and the lowest in vivo dose at which a chemical causes toxicity. We also found associations between a small set of in vitro assays and rodent liver lesion formation. This approach promises to provide meaningful data on the thousands of untested environmental chemicals and to guide targeted testing of environmental contaminants.

Toxicity Screening of the ToxCast Chemical Library Using a Zebrafish Developmental Assay

EPA Science Inventory

As part of the chemical screening and prioritization research program of the U.S. Environmental Protection Agency, the toxicity of the 320 ToxCast™ Phase I chemicals were assessed using a vertebrate screen of developmental toxicity. Zebrafish embryos/larvae (Danio rerio) were exp...

Tiered High-Throughput Screening Approach to Identify Thyroperoxidase Inhibitors within the ToxCast Phase I and II Chemical Libraries

EPA Science Inventory

High-throughput screening (HTS) for potential thyroid–disrupting chemicals requires a system of assays to capture multiple molecular-initiating events (MIEs) that converge on perturbed thyroid hormone (TH) homeostasis. Screening for MIEs specific to TH-disrupting pathways is limi...

A High-Throughput Screening Assay to Detect Thyroperoxidase Inhibitors (Teratology Society)

EPA Science Inventory

In support of the Endocrine Disruption Screening Program (EDSP21), the US EPA ToxCast program is developing assays to enable screening for chemicals that may disrupt thyroid hormone synthesis. Thyroperoxidase (TPO) is critical for TH synthesis and is a known target of thyroid-dis...

Computational Modeling and Simulation of Developmental ...

EPA Pesticide Factsheets

Developmental and Reproductive Toxicity (DART) testing is important for assessing the potential consequences of drug and chemical exposure on human health and well-being. Complexity of pregnancy and the reproductive cycle makes DART testing challenging and costly for traditional (animal-based) methods. A compendium of in vitro data from ToxCast/Tox21 high-throughput screening (HTS) programs is available for predictive toxicology. ‘Predictive DART’ will require an integrative strategy that mobilizes HTS data into in silico models that capture the relevant embryology. This lecture addresses progress on EPA's 'virtual embryo'. The question of how tissues and organs are shaped during development is crucial for understanding (and predicting) human birth defects. While ToxCast HTS data may predict developmental toxicity with reasonable accuracy, mechanistic models are still necessary to capture the relevant biology. Subtle microscopic changes induced chemically may amplify to an adverse outcome but coarse changes may override lesion propagation in any complex adaptive system. Modeling system dynamics in a developing tissue is a multiscale problem that challenges our ability to predict toxicity from in vitro profiling data (ToxCast/Tox21). (DISCLAIMER: The views expressed in this presentation are those of the presenter and do not necessarily reflect the views or policies of the US EPA). This was an invited seminar presentation to the National Institute for Public H

Translating Computational Toxicology Data Through ...

EPA Pesticide Factsheets

US EPA has been using in vitro testing methods in an effort to accelerate the pace of chemical evaluations and address the significant lack of health and environmental data on the thousands of chemicals found in commonly used products. Since 2005, EPA’s researchers have generated hazard data using in vitro methods for thousands chemicals, designed innovative chemical exposure prediction models, and created a repository of thousands of high quality chemical structure data. Recently, EPA's ToxCast research effort, released high-throughput screening data on thousands of chemicals. These chemicals were screened for potential health effects in over 700 high-throughput screening assay endpoints. As part of EPA’s commitment to transparency, all data is accessible through the Chemical Safety for Sustainability Dashboard (iCSS). Policy makers and stakeholders can analyze and use this data to help inform decisions they make about chemicals. Use of these new datasets in risk decisions will require changing a regulatory paradigm that has been used for decades. EPA recognized early in the ToxCast effort that a communications and outreach strategy was needed to parallel the research and aid with the development and use of these new data sources. The goal is to use communications and outreach to increase awareness, interest and usage of analyzing and using these new chemical evaluation methods. To accomplish this, EPA employs numerous communication and outreach including t

Toxicity ForeCaster (ToxCast™) Data

EPA Pesticide Factsheets

Data is organized into different data sets and includes descriptions of ToxCast chemicals and assays and files summarizing the screening results, a MySQL database, chemicals screened through Tox21, and available data generated from animal toxicity studies.

Forecasting Exposure in Order to Use High Throughput Hazard Data in a Risk-based Context (WC9)

EPA Science Inventory

The ToxCast program and Tox21 consortium have evaluated over 8000 chemicals using in vitro high-throughput screening (HTS) to identify potential hazards. Complementary exposure science needed to assess risk, and the U.S. Environmental Protection Agency (EPA)’s ExpoCast initiative...

Enhancing high throughput toxicology - development of putative adverse outcome pathways linking US EPA ToxCast screening targets to relevant apical hazards.

EPA Science Inventory

High throughput toxicology programs, such as ToxCast and Tox21, have provided biological effects data for thousands of chemicals at multiple concentrations. Compared to traditional, whole-organism approaches, high throughput assays are rapid and cost-effective, yet they generall...

Identifying Functionally Linked Gene Modules Within Biological Pathways Assessed by ToxCast In Vitro Assays

EPA Science Inventory

The US EPA ToxCast program is using in vitro high-throughput screening assays to profile the bioactivity of environmental chemicals, with the ultimate goal of predicting in vivo toxicity. We hypothesize that in modeling toxicity it will be more constructive to understand the pert...

Evaluation of 1066 ToxCast Chemicals in a human stem cell assay for developmental toxicity (SOT)

EPA Science Inventory

To increase the diversity of assays used to assess potential developmental toxicity, the ToxCast chemical library was screened in the Stemina devTOX quickPREDICT assay using human embryonic stem (hES) cells. A model for predicting teratogenicity was based on a training set of 23 ...

Quantitative Model of Systemic Toxicity Using ToxCast and ToxRefDB (SOT)

EPA Science Inventory

EPA’s ToxCast program profiles the bioactivity of chemicals in a diverse set of ~700 high throughput screening (HTS) assays. In collaboration with L’Oreal, a quantitative model of systemic toxicity was developed using no effect levels (NEL) from ToxRefDB for 633 chemicals with HT...

Virtual Liver: Evaluating the Impact of Hepatic Microdosimetry for ToxCast Chemicals

EPA Science Inventory

The U.S. EPA’s ToxCastTM program uses hundreds of high-throughput, in vitro assays to screen chemicals for potential toxicity. The assays are used to probe in vitro concentrations at which target cellular pathways and processes are perturbed by these chemicals. The U.S. EPA’s Vir...

Differentiating high priority pathway-based toxicity from non ...

EPA Pesticide Factsheets

The ToxCast chemical screening approach enables the rapid assessment of large numbers of chemicals for biological effects, primarily at the molecular level. Adverse outcome pathways (AOPs) offer a means to link biomolecular effects with potential adverse outcomes at the level of the individual or population, thus enhancing the utility of the ToxCast effort for hazard assessment. Thus, efforts are underway to develop AOPs relevant to the pathway perturbations detected in ToxCast assays. However, activity (?‘hits’) determined for chemical-assay pairs may reflect target-specific activity relevant to a molecular initiating event of an AOP, or more generalized cell stress and cytotoxicity-mediated effects. Previous work identified a ?‘cytotoxic burst’ phenomenon wherein large numbers of assays begin to respond at or near concentrations that elicit cytotoxicity. The concentration range at which the “burst” occurs is definable, statistically. Consequently, in order to focus AOP development on the ToxCast assay targetswhich are most sensitive and relevant to pathway-specific effects, we conducted a meta-analysis to identify which assays were frequently responding at concentrations well below the cytotoxic burst. Assays were ranked by the fraction of chemical hits below the burst concentration range compared to the number of chemicals tested, resulting in a preliminary list of potentially important, target-specific assays. After eliminating cytotoxicity a

Survey of ecotoxicologically-relevant reproductive endpoint coverage within the ECOTOX database across ToxCast ER agonists (ASCCT)

EPA Science Inventory

The U.S. EPA’s Endocrine Disruptor Screening Program (EDSP) has been charged with screening thousands of chemicals for their potential to affect the endocrine systems of humans and wildlife. In vitro high throughput screening (HTS) assays have been proposed as a way to prioritize...

High-throughput Screening of ToxCast" Phase I Chemicals in an Embryonic Stem Cell Assay Reveals Potential Disruption of a Critical Developmental Signaling Pathway

EPA Science Inventory

Little is known about the developmental toxicity of the expansive chemical landscape in existence today. Significant efforts are being made to apply novel methods to predict developmental activity of chemicals utilizing high-throughput screening (HTS) and high-content screening (...

Uncertainty Quantification in High Throughput Screening: Applications to Models of Endocrine Disruption, Cytotoxicity, and Zebrafish Development (GRC Drug Safety)

EPA Science Inventory

Using uncertainty quantification, we aim to improve the quality of modeling data from high throughput screening assays for use in risk assessment. ToxCast is a large-scale screening program that analyzes thousands of chemicals using over 800 assays representing hundreds of bioche...

High-Throughput Screening and Quantitative Chemical Ranking for Sodium Iodide Symporter Inhibitors in ToxCast Phase 1 Chemical Library

EPA Science Inventory

The U.S. EPA’s Endocrine Disruptor Screening Program (EDSP) and Office of Research and Development (ORD) are currently developing high throughput assays to screen chemicals that may alter the thyroid hormone pathway. One potential target in this pathway is the sodium iodide...

High-Throughput Screening and Quantitative Chemical Ranking for Sodium Iodide Symporter Inhibitors in ToxCast Phase 1 Chemical Library

EPA Science Inventory

The U.S. EPA’s Endocrine Disruptor Screening Program (EDSP) and Office of Research and Development (ORD) are currently developing high throughput assays to screen chemicals that may alter the thyroid hormone pathway. One potential target in this pathway is the sodium iodide sympo...

Screening for angiogenic inhibitors in zebrafish to evaluate a predictive model for developmental vascular toxicity.

PubMed

Tal, Tamara; Kilty, Claire; Smith, Andrew; LaLone, Carlie; Kennedy, Brendán; Tennant, Alan; McCollum, Catherine W; Bondesson, Maria; Knudsen, Thomas; Padilla, Stephanie; Kleinstreuer, Nicole

2017-06-01

Chemically-induced vascular toxicity during embryonic development may cause a wide range of adverse effects. To identify putative vascular disrupting chemicals (pVDCs), a predictive pVDC signature was constructed from 124 U.S. EPA ToxCast high-throughput screening (HTS) assays and used to rank 1060 chemicals for their potential to disrupt vascular development. Thirty-seven compounds were selected for targeted testing in transgenic Tg(kdrl:EGFP) and Tg(fli1:EGFP) zebrafish embryos to identify chemicals that impair developmental angiogenesis. We hypothesized that zebrafish angiogenesis toxicity data would correlate with human cell-based and cell-free in vitro HTS ToxCast data. Univariate statistical associations used to filter HTS data based on correlations with zebrafish angiogenic inhibition in vivo revealed 132 total significant associations, 33 of which were already captured in the pVDC signature, and 689 non-significant assay associations. Correlated assays were enriched in cytokine and extracellular matrix pathways. Taken together, the findings indicate the utility of zebrafish assays to evaluate an HTS-based predictive toxicity signature and also provide an experimental basis for expansion of the pVDC signature with novel HTS assays. Published by Elsevier Inc.

Prevalence of β-thalassemia and other haemoglobinopathies in six cities in India: a multicentre study.

PubMed

Mohanty, D; Colah, R B; Gorakshakar, A C; Patel, R Z; Master, D C; Mahanta, J; Sharma, S K; Chaudhari, U; Ghosh, M; Das, S; Britt, R P; Singh, S; Ross, C; Jagannathan, L; Kaul, R; Shukla, D K; Muthuswamy, V

2013-01-01

The population of India is extremely diverse comprising of more than 3,000 ethnic groups who still follow endogamy. Haemoglobinopathies are the commonest hereditary disorders in India and pose a major health problem. The data on the prevalence of β-thalassemias and other haemoglobinopathies in different caste/ethnic groups of India is scarce. Therefore the present multicentre study was undertaken in six cities of six states of India (Maharashtra, Gujarat, West Bengal, Assam, Karnataka and Punjab) to determine the prevalence of haemoglobinopathies in different caste/ethnic groups using uniform methodology. Fifty-six thousand seven hundred eighty individuals (college students and pregnant women) from different caste/ethnic groups were screened. RBC indices were measured on an automated haematology counter while the percentage of HbA(2), HbF and other abnormal Hb variants were estimated by HPLC on the Variant Hemoglobin Testing System. The overall prevalence of β-thalassemia trait was 2.78 % and varied from 1.48 to 3.64 % in different states, while the prevalence of β-thalassemia trait in 59 ethnic groups varied from 0 to 9.3 %. HbE trait was mainly seen in Dibrugarh in Assam (23.9 %) and Kolkata in West Bengal (3.92 %). In six ethnic groups from Assam, the prevalence of HbE trait varied from 41.1 to 66.7 %. Few subjects with δβ-thalassemia, HPFH, HbS trait, HbD trait, HbE homozygous and HbE β-thalassemia as well as HbS homozygous and HbS-β-thalassemia (<1 %) were also identified. This is the first large multicentre study covering cities from different regions of the country for screening for β-thalassemia carriers and other haemoglobinopathies where uniform protocols and methodology was followed and quality control ensured by the co-ordinating centre. This study also shows that establishment of centres for screening for β-thalassemia and other haemoglobinopathies is possible in medical colleges. Creating awareness, screening and counselling can be done at these centres. This experience will help to formulate a national thalassemia control programme in India.

Causal Inferences from Mining ToxCast Data and the Biomedical Literature for Molecular Pathways and Cellular Processes in Cleft Palate (SOT)

EPA Science Inventory

Sixty-five chemicals in the ToxCast high-throughput screening (HTS) dataset have been linked to cleft palate based on data from ToxRefDB (rat or rabbit prenatal developmental toxicity studies) or from literature reports. These compounds are structurally diverse and thus likely to...

Breaking into the Business: Experiences of Actors with Disabilities in the Entertainment Industry

ERIC Educational Resources Information Center

Raynor, Olivia; Hayward, Katharine

2009-01-01

The pursuit of an acting career is a difficult one for anybody. However, studies have yet to factor how disability affects casting opportunities. This study describes the employment of actors with disabilities, along with the unique barriers they encounter in the audition and casting process. Actors with disabilities from the Screen Actors Guild…

DSSTox ToxCast and Tox21 Chemical Inventories: Laying the Foundation for the U.S. EPA’s Computational Toxicology Research Programs

EPA Science Inventory

High quality chemical structure inventories provide the foundation of the U.S. EPA’s ToxCast and Tox21 projects, which are employing high-throughput technologies to screen thousands of chemicals in hundreds of biochemical and cell-based assays, probing a wide diversity of targets...

Quick and Easy: Use Screen Capture Software to Train and Communicate

ERIC Educational Resources Information Center

Schuster, Ellen

2011-01-01

Screen capture (screen cast) software can be used to develop short videos for training purposes. Developing videos is quick and easy. This article describes how these videos are used as tools to reinforce face-to-face and interactive TV curriculum training in a nutrition education program. Advantages of developing these videos are shared.…

Chemical-Gene Interactions from ToxCast Bioactivity Data ...

EPA Pesticide Factsheets

Characterizing the effects of chemicals in biological systems is often summarized by chemical-gene interactions, which have sparse coverage in the literature. The ToxCast chemical screening program has produced bioactivity data for nearly 2000 chemicals and over 450 gene targets. To evaluate the information gained from the ToxCast project, a ToxCast bioactivity network was created comprising ToxCast chemical-gene interactions based on assay data and compared to a chemical-gene association network from literature. The literature network was compiled from PubMed articles, excluding ToxCast publications, mapped to genes and chemicals. Genes were identified by curated associations available from NCBI while chemicals were identified by PubChem submissions. The frequencies of chemical-gene associations from the literature network were log-scaled and then compared to the ToxCast bioactivity network. In total, 140 times more chemical-gene associations were present in the ToxCast network in comparison to the literature-derived network highlighting the vast increase in chemical-gene interactions putatively elucidated by the ToxCast research program. There were 165 associations found in the literature network that were reproduced by ToxCast bioactivity data, and 336 associations in the literature network were not reproduced by the ToxCast bioactivity network. The literature network relies on the assumption that chemical-gene associations represent a true chemical-gene inte

Identification of Chemical Features Linked to Thyroperoxidase Inhibition (SOT)

EPA Science Inventory

Disruption of maternal serum thyroid hormone (TH) adversely affects fetal neurodevelopment. Therefore, assay development within the US EPA ToxCast program is ongoing to enable screening for chemicals that may disrupt TH, in support of the Endocrine Disruption Screening Program (E...

Biological Profiling of Endocrine Related Effects of Chemicals in ToxCast

EPA Science Inventory

The Food Quality Protection Act of 1996 mandates that EPA implement a validated screening program for detecting estrogenic chemicals, as well as other endocrine targets deemed appropriate by the Administrator. EPA’s Endocrine Disruptor Screening Program (EDSP) has been developing...

Biological Profiling of Endocrine Related Effects of Chemicals Using ToxCast

EPA Science Inventory

The Food Quality Protection Act of 1996 mandates that EPA implement a validated screening program for detecting estrogenic chemicals, as well as other endocrine targets deemed appropriate by the Administrator. EPA’s Endocrine Disruptor Screening Program (EDSP) has been developing...

Pathway Profiling and Tissue Modeling Using ToxCast HTS Data

EPA Science Inventory

High-throughput screening (HTS) and high-content screening (HCS) assays are providing data-rich studies to probe and profile the direct cellular effects of thousands of chemical compounds in commerce or potentially entering the environment. In vitro profiling may compare unknown ...

A catalog of putative adverse outcome pathways (AOPs) that ...

EPA Pesticide Factsheets

A number of putative AOPs for several distinct MIEs of thyroid disruption have been formulated for amphibian metamorphosis and fish swim bladder inflation. These have been entered into the AOP knowledgebase on the OECD WIKI. The EDSP has been actively advancing high-throughput screening for chemical activity toward estrogen, androgen and thyroid targets. However, it has been recently identified that coverage for thyroid-related targets is lagging behind estrogen and androgen assay coverage. As thyroid-related medium-high throughput assays are actively being developed for inclusion in the ToxCast chemical screening program, a parallel effort is underway to characterize putative adverse outcome pathways (AOPs) specific to these thyroid-related targets. This effort is intended to provide biological and ecological context that will enhance the utility of ToxCast high throughput screening data for hazard identification.

Virtual Liver: Estimating Proliferation and Apoptosis of Hepatocytes Exposed to Environmental Chemicals Using ToxCastTM Data

EPA Science Inventory

The U.S. EPA’s ToxCastTM program has screened over a thousand chemicals for potential toxicity using hundreds of high-throughput, in vitro assays. The U.S. EPA’s Virtual Liver (v-Liver™) is a cellular systems model of hepatic tissues that enables the estimation of in vivo effects...

Extending the Derek-Meteor Workflow to Predict Chemical-Toxicity Space Impacted by Metabolism: Application to ToxCast and Tox21 Chemical Inventories

EPA Science Inventory

A central aim of EPA’s ToxCast project is to use in vitro high-throughput screening (HTS) profiles to build predictive models of in vivo toxicity. Where assays lack metabolic capability, such efforts may need to anticipate the role of metabolic activation (or deactivation). A wo...

EPA's ToxCast Project: Lessons learned and future directions for use of HTS in predicting in vivo toxicology -- A Chemical Perspective

EPA Science Inventory

U.S. EPA’s ToxCast and the related Tox21 projects are employing high-throughput screening (HTS) technologies to profile thousands of chemicals, which in turn serve as probes of a wide diversity of targets, pathways and mechanisms related to toxicity. Initial models relating ToxCa...

Supplemental Immobilization of Hanford Low-Activity Waste: Cast Stone Screening Tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Westsik, Joseph H.; Piepel, Gregory F.; Lindberg, Michael J.

2013-09-30

More than 56 million gallons of radioactive and hazardous waste are stored in 177 underground storage tanks at the U.S. Department of Energy’s (DOE’s) Hanford Site in southeastern Washington State. The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is being constructed to treat the wastes and immobilize them in a glass waste form. The WTP includes a pretreatment facility to separate the wastes into a small volume of high-level waste (HLW) containing most of the radioactivity and a larger volume of low-activity waste (LAW) containing most of the nonradioactive chemicals. The HLW will be converted to glass in themore » HLW vitrification facility for ultimate disposal at an offsite federal repository. At least a portion (~35%) of the LAW will be converted to glass in the LAW vitrification facility and will be disposed of onsite at the Integrated Disposal Facility (IDF). The pretreatment and HLW vitrification facilities will have the capacity to treat and immobilize the wastes destined for each facility. However, a second LAW immobilization facility will be needed for the expected volume of LAW requiring immobilization. A cementitious waste form known as Cast Stone is being considered to provide the required additional LAW immobilization capacity. The Cast Stone waste form must be acceptable for disposal in the IDF. The Cast Stone waste form and immobilization process must be tested to demonstrate that the final Cast Stone waste form can comply with the waste acceptance criteria for the disposal facility and that the immobilization processes can be controlled to consistently provide an acceptable waste form product. Further, the waste form must be tested to provide the technical basis for understanding the long-term performance of the waste form in the disposal environment. These waste form performance data are needed to support risk assessment and performance assessment (PA) analyses of the long-term environmental impact of the waste disposal in the IDF. The PA is needed to satisfy both Washington State IDF Permit and DOE Order requirements. Cast Stone has been selected for solidification of radioactive wastes including WTP aqueous secondary wastes treated at the Effluent Treatment Facility (ETF) at Hanford. A similar waste form called Saltstone is used at the Savannah River Site (SRS) to solidify its LAW tank wastes.« less

Making Movies: From Script to Screen.

ERIC Educational Resources Information Center

Bobker, Lee R.

This book is a guide to the making of films. It covers preparation (scripting, storyboarding, budgeting, casting, and crew selection), filming (directing, camera operating, and sound recording), and postproduction (editing, sound dubbing, laboratory processing, and trial screening). Distribution of films is discussed in detail. Possible careers in…

Environmental Impact on Vascular Development Predicted by High Throughput Screening

EPA Science Inventory

Understanding health risks to embryonic development from exposure to environmental chemicals is a significant challenge given the diverse chemical landscape and paucity of data for most of these compounds. High throughput screening (HTS) in EPA’s ToxCastTM project provides vast d...

Improved Foundry Castings Utilizing CAD/CAM (Computer Aided Design/ Computer Aided Manufacture). Volume 1. Overview

DTIC Science & Technology

1988-06-30

casting. 68 Figure 1-9: Line printer representation of roll solidification. 69 Figure I1-1: Test casting model. 76 Figure 11-2: Division of test casting...writing new casting analysis and design routines. The new routines would take advantage of advanced criteria for predicting casting soundness and cast...properties and technical advances in computer hardware and software. 11 2. CONCLUSIONS UPCAST, a comprehensive software package, has been developed for

Identifying developmental toxicity pathways for a subset of ToxCast chemicals using human embryonic stem cells and metabolomics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleinstreuer, N.C., E-mail: kleinstreuer.nicole@epa.gov; Smith, A.M.; West, P.R.

2011-11-15

Metabolomics analysis was performed on the supernatant of human embryonic stem (hES) cell cultures exposed to a blinded subset of 11 chemicals selected from the chemical library of EPA's ToxCast Trade-Mark-Sign chemical screening and prioritization research project. Metabolites from hES cultures were evaluated for known and novel signatures that may be indicative of developmental toxicity. Significant fold changes in endogenous metabolites were detected for 83 putatively annotated mass features in response to the subset of ToxCast chemicals. The annotations were mapped to specific human metabolic pathways. This revealed strong effects on pathways for nicotinate and nicotinamide metabolism, pantothenate and CoAmore » biosynthesis, glutathione metabolism, and arginine and proline metabolism pathways. Predictivity for adverse outcomes in mammalian prenatal developmental toxicity studies used ToxRefDB and other sources of information, including Stemina Biomarker Discovery's predictive DevTox Registered-Sign model trained on 23 pharmaceutical agents of known developmental toxicity and differing potency. The model initially predicted developmental toxicity from the blinded ToxCast compounds in concordance with animal data with 73% accuracy. Retraining the model with data from the unblinded test compounds at one concentration level increased the predictive accuracy for the remaining concentrations to 83%. These preliminary results on a 11-chemical subset of the ToxCast chemical library indicate that metabolomics analysis of the hES secretome provides information valuable for predictive modeling and mechanistic understanding of mammalian developmental toxicity. -- Highlights: Black-Right-Pointing-Pointer We tested 11 environmental compounds in a hESC metabolomics platform. Black-Right-Pointing-Pointer Significant changes in secreted small molecule metabolites were observed. Black-Right-Pointing-Pointer Perturbed mass features map to pathways critical for normal development and pregnancy. Black-Right-Pointing-Pointer Arginine, proline, nicotinate, nicotinamide and glutathione pathways were affected.« less

Comparison of intra-oral and study cast measurements in the assessment of malocclusion.

PubMed

Ovsenik, Maja; Farcnik, Franc M; Verdenik, Ivan

2004-06-01

Malocclusion assessment methods are based on registrations and measurements made on study casts, which requires that impressions be taken. In addition to being costly and time-consuming, this process can be unpleasant for very young children. Therefore, the aim of this study was to evaluate the reliability of intra-oral measurements that compute a malocclusion index score to determine malocclusion severity in the mixed dentition. The research was part of a longitudinal study in Slovenia on a sample of 530 3-year-old children. At 8 years of age (mean 8.5 years, standard deviation 0.2), a cohort of 101 children (44 boys, 57 girls) was randomly selected in a cross-sectional study. Quantitative registrations of space and occlusal anomalies were performed intra-orally as well as on study casts. Kappa (kappa) statistics were used to evaluate the agreement between clinical and study cast malocclusion assessments. Systematic bias of measurements was tested using Wilcoxon's signed rank test. The results showed complete agreement between the two measurements for anterior crossbite, anterior open bite and overjet scores (kappa = 1); excellent reliability for the buccal segment relationship (kappa = 0.93), transverse occlusion of posterior teeth (kappa = 0.87); and substantial agreement for overbite (kappa = 0.79) and midline deviation (kappa = 0.71). For the remainder of the traits the agreement was moderate: rotation of incisors (kappa = 0.58), crowding of upper incisors (kappa = 0.51), axial inclination of teeth (kappa = 0.44) and lower incisor crowding (kappa = 0.41). Intra-orally small, but statistically significant scoring of lower incisor rotation and crowding was identified. On the study casts the most favourable axial inclination was found for buccal segment occlusion. Overall classification into severity grades, based on the total malocclusion score, showed excellent agreement between the two methods (kappa = 0.89), without statistically significant bias. Malocclusion assessment, recorded and measured intra-orally, is as reliable as assessment on study casts. The proposed method can be used in screening, in epidemiological studies and in clinical orthodontic assessment.

Development of a tiered screening strategy for a molecular-initiating event: thyroperoxidase inhibition (SOT)

EPA Science Inventory

Adverse outcome pathway (AOP) analyses illustrate that some molecular-initiating events (MIEs) for thyroid disruption, including thyroperoxidase (TPO) inhibition, are not evaluated by current ToxCast/Tox21 high-throughput screening (HTS) assays. A novel HTS assay for TPO inhibiti...

Retrofit Strategies for Incorporating Xenobiotic Metabolism into High Throughput Screening Assays (EMGS)

EPA Science Inventory

The US EPA’s ToxCast program is designed to assess chemical perturbations of molecular and cellular endpoints using a variety of high-throughput screening (HTS) assays. However, existing HTS assays have limited or no xenobiotic metabolism which could lead to a mischaracterization...

Defining the taxonomic domain of applicability for mammalian-based high-throughput screening assays

EPA Science Inventory

Cell-based high throughput screening (HTS) technologies are becoming mainstream in chemical safety evaluations. The US Environmental Protection Agency (EPA) Toxicity Forecaster (ToxCastTM) and the multi-agency Tox21 Programs have been at the forefront in advancing this science, m...

Tiered High-Throughput Screening Approach to Identify ...

EPA Pesticide Factsheets

High-throughput screening (HTS) for potential thyroid–disrupting chemicals requires a system of assays to capture multiple molecular-initiating events (MIEs) that converge on perturbed thyroid hormone (TH) homeostasis. Screening for MIEs specific to TH-disrupting pathways is limited in the US EPA ToxCast screening assay portfolio. To fill one critical screening gap, the Amplex UltraRed-thyroperoxidase (AUR-TPO) assay was developed to identify chemicals that inhibit TPO, as decreased TPO activity reduces TH synthesis. The ToxCast Phase I and II chemical libraries, comprised of 1,074 unique chemicals, were initially screened using a single, high concentration to identify potential TPO inhibitors. Chemicals positive in the single concentration screen were retested in concentration-response. Due to high false positive rates typically observed with loss-of-signal assays such as AUR-TPO, we also employed two additional assays in parallel to identify possible sources of nonspecific assay signal loss, enabling stratification of roughly 300 putative TPO inhibitors based upon selective AUR-TPO activity. A cell-free luciferase inhibition assay was used to identify nonspecific enzyme inhibition among the putative TPO inhibitors, and a cytotoxicity assay using a human cell line was used to estimate the cellular tolerance limit. Additionally, the TPO inhibition activities of 150 chemicals were compared between the AUR-TPO and an orthogonal peroxidase oxidation assay using

Manufacturing and High Heat Flux Testing of Brazed Flat-Type W/CuCrZr Plasma Facing Components

NASA Astrophysics Data System (ADS)

Lian, Youyun; Liu, Xiang; Feng, Fan; Chen, Lei; Cheng, Zhengkui; Wang, Jin; Chen, Jiming

2016-02-01

Water-cooled flat-type W/CuCrZr plasma facing components with an interlayer of oxygen-free copper (OFC) have been developed by using vacuum brazing route. The OFC layer for the accommodation of thermal stresses was cast onto the surface of W at a temperature range of 1150 °C-1200 °C in a vacuum furnace. The W/OFC cast tiles were vacuum brazed to a CuCrZr heat sink at 940 °C using the silver-free filler material CuMnSiCr. The microstructure, bonding strength, and high heat flux properties of the brazed W/CuCrZr joint samples were investigated. The W/Cu joint exhibits an average tensile strength of 134 MPa, which is about the same strength as pure annealed copper. High heat flux tests were performed in the electron beam facility EMS-60. Experimental results indicated that the brazed W/CuCrZr mock-up experienced screening tests of up to 15 MW/m2 and cyclic tests of 9 MW/m2 for 1000 cycles without visible damage. supported by National Natural Science Foundation of China (No. 11205049) and the National Magnetic Confinement Fusion Science Program of China (No. 2011GB110004)

Heavy Metals in ToxCast: Relevance to Food Safety (SOT) ...

EPA Pesticide Factsheets

Human exposure to heavy metals occurs through food contamination due to industrial processes, vehicle emissions and farming methods. Specific toxicity endpoints have been associated with metal exposures, e.g. lead and neurotoxicity; however, numerous varieties of heavy metals have not been systematically examined for potential toxicities. We describe results from testing a large set of heavy metal-containing compounds in extensive suites of in vitro assays to suggest possible molecular initiating events in toxicity pathways. A broad definition of heavy metals that includes As, Se and organometallics or inorganic salts containing metals in Group III or higher (MW > 40) was used to identify 75 different compounds tested in the EPA’s ToxCast assays encompassing biochemical, cellular and model organism assays. These 75, plus an additional 100 metal-containing compounds, were tested in Tox21 quantitative high-throughput screening (qHTS) assays covering nuclear receptor and stress pathways. Known activities were confirmed such as activation of stress pathways and nuclear receptors (RXR, PPARg) as well as overt cytotoxicity. Specifically, organotin and organomercury were among the most potent of over 8K chemicals tested. The HTS results support known toxicities, including promiscuous GPCR activity for mercury compounds consistent with the neuropsychiatric effects seen in mercury poisoning (Mad Hatter’s Syndrome). As such, HTS approaches provide an efficient method

UV-screening, transparency and water barrier properties of semi refined iota carrageenan packaging film incorporated with ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Khoirunnisa, Assifa Rahma; Joni, I. Made; Panatarani, Camellia; Rochima, Emma; Praseptiangga, Danar

2018-02-01

This study aims to develop film for food packaging application with high UV-screening, transparency and water barrier properties. Semi refined iota carrageenan (SRiC) nanocomposite films prepared by addition of zinc oxide (ZnO) nanoparticles as nanofiller using solution casting method. The effect of nanofiller with different concentration (0%, 0.5%, 1.0%, 1.5% w/w carrageenan) on UV-screening, transparency and water barrier properties of films were tested. The water barrier properties of the films were studied by measuring water vapor permeability (WVP) and the optical properties of the films were studied by using UV-Vis spectrophotometer at 280 nm for UV-screening test and at 660 nm for transparency test. WVP value of carrageenan films with addition of ZnO is low compared to a control carrageenan film and the lowest WVP value was found for the film with addition of 1.5% of ZnO. These result indicate that the addition of ZnO had a positive effect on the water barrier properties of the carrageenan matrix. Increase in the concentration of nanofiller leads to an increase in the UV-screening properties. Among all the films, carrageenan film with 1.5% ZnO has the highest UV-screening. The result showed that adding 0.5% and 1.0% of ZnO was insignificantly affect transparency of the films, however the transparency decreased sligthly when 1.5% ZnO was added. In conclusion, incorporating no more than 1.0% of ZnO to the films can obtain films with high UV-screening, transparency and water barrier properties and suitable for food packaging application.

In silico study of in vitro GPCR assays by QSAR modeling

EPA Science Inventory

The U.S. EPA is screening thousands of chemicals of environmental interest in hundreds of in vitro high-throughput screening (HTS) assays (the ToxCast program). One goal is to prioritize chemicals for more detailed analyses based on activity in molecular initiating events (MIE) o...

Extrapolating toxicity data across species using U.S. EPA SeqAPASS tool

EPA Science Inventory

In vitro high-throughput screening (HTS) and in silico technologies have emerged as 21st century tools for chemical hazard identification. In 2007 the U.S. Environmental Protection Agency (EPA) launched the ToxCast Program, which has screened thousands of chemicals in hundreds of...

Screening for angiogenic inhibitors in zebrafish to evaluate a predictive model for developmental vascular toxicity

EPA Science Inventory

Chemically-induced vascular toxicity during embryonic development may cause a wide range of adverse effects. To identify putative vascular disrupting chemicals (pVDCs), a predictive signature was constructed from U.S. EPA ToxCast high-throughput screening (HTS) assays that map to...

Chemical Screening for Bioactivated Electrophilic Metabolites Using Alginate Immobilization of Metabolic Enzymes (AIME) (SOT)

EPA Science Inventory

The US EPA's ToxCast program is designed to assess chemical perturbations of molecular and cellular endpoints using a variety of high-throughput screening (HTS) assays. However, existing HTS assays have limited or no xenobiotic metabolism which could lead to a mischaracterization...

Alginate Immobilization of Metabolic Enzymes (AIME) for High-Throughput Screening Assays (SOT)

EPA Science Inventory

Alginate Immobilization of Metabolic Enzymes (AIME) for High-Throughput Screening Assays DE DeGroot, RS Thomas, and SO SimmonsNational Center for Computational Toxicology, US EPA, Research Triangle Park, NC USAThe EPA’s ToxCast program utilizes a wide variety of high-throughput s...

Recent Developments in Toxico-Cheminformatics and Progress Towards a New Paradigm for Predictive Toxicology

EPA Science Inventory

EPA’s Computational Toxicology Center is building capabilities to support a new paradigm for toxicity screening and prediction through harnessing of legacy toxicity data, creation of data linkages, and generation of new in vitro screening data. In association with EPA’s ToxCastTM...

β-Thalassemia mutations in Western India: outcome of prenatal diagnosis in a hemoglobinopathies project.

PubMed

Patel, Ashwin P; Patel, Rupesh B; Patel, Saumyaa A; Vaniawala, Salil N; Patel, Dipika S; Shrivastava, Naina S; Sharma, Narmadeshwar P; Zala, Jayendrasinh V; Parmar, Prakash H; Naik, Madhuben R

2014-01-01

Prenatal diagnosis (PND) is one of the most cost effective preventive methods, but it is available only in the large cities of India. Therefore, we initiated a program that offers PND and allows us to determine the prevalence of various mutations. Pregnant females (n = 111,426) were screened for hemoglobinopathies using complete blood count (CBC) and high performance liquid chromatography (HPLC). If the female had a hemoglobinopathy, her husband was then tested. If hemoglobinopathies were seen in both partners, a genetic mutation study was performed on the couple. Fetal samples were obtained by either chorionic villus sampling (CVS) in 70.6% or amniocentesis in 29.4%. The study included 282 couples. IVS-I-5 (G > C) was the most common mutation in all castes except in the Sindhis and Lohanas, where the 619 bp deletion was the most common. Prenatal testing was informative in 97.9% of the couples. A significant number of couples (41.0%) underwent PND during their first pregnancy. Seven patients with β-thalassemia (β-thal) trait had normal Hb A2 levels. The Hb A2 and Hb F values varied significantly (p < 0.0001 and 0.0082, respectively) among mutations associated with β-thal. The IVS-I-5, 619 bp deletion, codons 41/42 (-CTTT), codons 8/9 (+G) and IVS-I-1 (G > T or G > A), were present in 81.0% of the couples tested. β-Thalassemia mutation frequency varied among the different castes, underlining the need for evolving a testing strategy that considers the caste system. Targeting antenatal clinics could also prove to be a most cost effective way of preventing hemoglobinopathies.

Tutorial Video Series: Using Stakeholder Outreach to Increase ...

EPA Pesticide Factsheets

The limited amount of toxicity data on thousands of chemicals found in consumer products has led to the development of research endeavors such as the U.S. EPA’s Toxicity Forecaster (ToxCast). ToxCast uses high-throughput screening technology to evaluate thousands of chemicals for potential toxicity. At the end of 2013, U.S. EPA released ToxCast chemical data on almost 2,000 chemicals through the interactive Chemical Safety for Sustainability (iCSS) Dashboard. The iCSS Dashboard provides public access to the high-throughput screening data that can be used to inform the evaluation of the safety of chemicals. U.S. EPA recognized early in the development of ToxCast that stakeholder outreach was needed in order to translate the complex scientific information featured in the iCSS Dashboard and data, with the goal of educating the diverse user community through targeted efforts to increase data usage and analysis. Through survey feedback and the request of stakeholders, a series of tutorial videos to demonstrate how to access and use the data has been planned, and the first video of the series has been released to guide data usage. This presentation will describe the video tutorial strategy including an overview of: 1) Stakeholder outreach goals and approach; 2) Planning, production, and dissemination of tutorial videos; 3) Overview of Survey Feedback; 4) Overview of tutorial video usage statistics and usage of the ToxCast data. This stakeholder-outreach approach

Robustness of Ability Estimation to Multidimensionality in CAST with Implications to Test Assembly

ERIC Educational Resources Information Center

Zhang, Yanwei; Nandakumar, Ratna

2006-01-01

Computer Adaptive Sequential Testing (CAST) is a test delivery model that combines features of the traditional conventional paper-and-pencil testing and item-based computerized adaptive testing (CAT). The basic structure of CAST is a panel composed of multiple testlets adaptively administered to examinees at different stages. Current applications…

Materials for Advanced Ultrasupercritical Steam Turbines Task 4: Cast Superalloy Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thangirala, Mani

The Steam Turbine critical stationary structural components are high integrity Large Shell and Valve Casing heavy section Castings, containing high temperature steam under high pressures. Hence to support the development of advanced materials technology for use in an AUSC steam turbine capable of operating with steam conditions of 760°C (1400°F) and 35 Mpa (5000 psia), Casting alloy selection and evaluation of mechanical, metallurgical properties and castability with robust manufacturing methods are mandated. Alloy down select from Phase 1 based on producability criteria and creep rupture properties tested by NETL-Albany and ORNL directed the consortium to investigate cast properties of Haynesmore » 282 and Haynes 263. The goals of Task 4 in Phase 2 are to understand a broader range of mechanical properties, the impact of manufacturing variables on those properties. Scale up the size of heats to production levels to facilitate the understanding of the impact of heat and component weight, on metallurgical and mechanical behavior. GE Power & Water Materials and Processes Engineering for the Phase 2, Task 4.0 Castings work, systematically designed and executed casting material property evaluation, multiple test programs. Starting from 15 lbs. cylinder castings to world’s first 17,000 lbs. poured weight, heavy section large steam turbine partial valve Haynes 282 super alloy casting. This has demonstrated scalability of the material for steam Turbine applications. Activities under Task 4.0, Investigated and characterized various mechanical properties of Cast Haynes 282 and Cast Nimonic 263. The development stages involved were: 1) Small Cast Evaluation: 4 inch diam. Haynes 282 and Nimonic 263 Cylinders. This provided effects of liquidus super heat range and first baseline mechanical data on cast versions of conventional vacuum re-melted and forged Ni based super alloys. 2) Step block castings of 300 lbs. and 600 lbs. Haynes 282 from 2 foundry heats were evaluated which demonstrated the importance of proper heat treat cycles for Homogenization, and Solutionizing parameters selection and implementation. 3) Step blocks casting of Nimonic 263: Carried out casting solidification simulation analysis, NDT inspection methods evaluation, detailed test matrix for Chemical, Tensile, LCF, stress rupture, CVN impact, hardness and J1C Fracture toughness section sensitivity data and were reported. 4) Centrifugal Casting of Haynes 282, weighing 1400 lbs. with hybrid mold (half Graphite and half Chromite sand) mold assembly was cast using compressor casing production tooling. This test provided Mold cooling rates influence on centrifugally cast microstructure and mechanical properties. Graphite mold section out performs sand mold across all temperatures for 0.2% YS; %Elongation, %RA, UTS at 1400°F. Both Stress-LMP and conditional Fracture toughness plots data were in the scatter band of the wrought alloy. 5) Fundamental Studies on Cooling rates and SDAS test program. Evaluated the influence of 6 mold materials Silica, Chromite, Alumina, Silica with Indirect Chills, Zircon and Graphite on casting solidification cooling rates. Actual Casting cooling rates through Liquidus to Solidus phase transition were measured with 3 different locations based thermocouples placed in each mold. Compared with solidification simulation cooling rates and measurement of SDAS, microstructure features were reported. The test results provided engineered casting potential methods, applicable for heavy section Haynes 282 castings for optimal properties, with foundry process methods and tools. 6) Large casting of Haynes 282 Drawings and Engineering FEM models and supplemental requirements with applicable specifications were provided to suppliers for the steam turbine proto type feature valve casing casting. Molding, melting and casting pouring completed per approved Manufacturing Process Plan during 2014 Q4. The partial valve casing was successfully cast after casting methods were validated with solidification simulation analysis and the casting met NDT inspection and acceptance criteria. Heat treated and sectioned to extract trepan samples at different locations comparing with cast on coupons test data. Material properties requisite for design, such as tensile, creep/rupture, LCF, Fracture Toughness, Charpy V-notch chemical analysis testing were carried out. The test results will be presented in the final report. The typical Haynes 282 large size Steam Turbine production casting from Order to Delivery foundry schedule with the activity break up is shown in Figures 107 and 108. • From Purchase Order placement to Casting pouring ~ 26 weeks. 1. Sales and commercial review 3 2. Engineering Drawings/models review 4 3. Pattern and core box manufacturing 6 4. Casting process engineering review 4 5. FEM and solidification simulation analysis 4 6. Gating & Feeder Attachments, Ceramic tiling 2 7. Molding and coremaking production scheduling 6 8. Melting planning and schedule 3 9. Pouring, cooling and shake out 2 • From Pouring to casting Delivery ~ 29 weeks 10. Shot blast and riser cutting, gates removal 3 11. Homogenizing , solutionizing HT furnace prep 4 12. Grinding, Fettling 2 13. Aging HT Cycle, cooling 2 14. VT and LPT NDT inspections 2 15. Radiographic inspection 4 16. Mechanical testing, Chemical analysis test certs 4 17. Casting weld repair upgrades and Aging PWHT 4 18. NDT after weld repairs and casting upgrades 3 19. Casting Final Inspection and test certifications 3 20. Package and delivery 2 Hence the Total Lead time from P.O to Casting delivery is approximately 55 weeks. The Task 4.2 and Task 4.3 activities and reporting completed.« less

Evaluation of food-relevant chemicals in the ToxCast high-throughput screening program

EPA Pesticide Factsheets

Thousands of chemicals are directly added to or come in contact with food, many of which have undergone little to no toxicological evaluation. The landscape of the food-relevant chemical universe was evaluated using cheminformatics, and subsequently the bioactivity of food-relevant chemicals across the publicly available ToxCast highthroughput screening program was assessed. In total, 8659 food-relevant chemicals were compiled including direct food additives, food contact substances, and pesticides. Of these food-relevant chemicals, 4719 had curated structure definition files amenable to defining chemical fingerprints, which were used to cluster chemicals using a selforganizing map approach. Pesticides, and direct food additives clustered apart from one another with food contact substances generally in between, supporting that these categories not only reflect different uses but also distinct chemistries. Subsequently, 1530 food-relevant chemicals were identified in ToxCast comprising 616 direct food additives, 371 food contact substances, and 543 pesticides. Bioactivity across ToxCast was filtered for cytotoxicity to identify selective chemical effects. Initiating analyses from strictly chemical-based methodology or bioactivity/cytotoxicity-driven evaluation presents unbiased approaches for prioritizing chemicals. Although bioactivity in vitro is not necessarily predictive of adverse effects in vivo, these data provide insight into chemical properties and cellu

A new method to acquire 3-D images of a dental cast

NASA Astrophysics Data System (ADS)

Li, Zhongke; Yi, Yaxing; Zhu, Zhen; Li, Hua; Qin, Yongyuan

2006-01-01

This paper introduced our newly developed method to acquire three-dimensional images of a dental cast. A rotatable table, a laser-knife, a mirror, a CCD camera and a personal computer made up of a three-dimensional data acquiring system. A dental cast is placed on the table; the mirror is installed beside the table; a linear laser is projected to the dental cast; the CCD camera is put up above the dental cast, it can take picture of the dental cast and the shadow in the mirror; while the table rotating, the camera records the shape of the laser streak projected on the dental cast, and transmit the data to the computer. After the table rotated one circuit, the computer processes the data, calculates the three-dimensional coordinates of the dental cast's surface. In data processing procedure, artificial neural networks are enrolled to calibrate the lens distortion, map coordinates form screen coordinate system to world coordinate system. According to the three-dimensional coordinates, the computer reconstructs the stereo image of the dental cast. It is essential for computer-aided diagnosis and treatment planning in orthodontics. In comparison with other systems in service, for example, laser beam three-dimensional scanning system, the characteristic of this three-dimensional data acquiring system: a. celerity, it casts only 1 minute to scan a dental cast; b. compact, the machinery is simple and compact; c. no blind zone, a mirror is introduced ably to reduce blind zone.

High-throughput screening (HTPS) of ToxCast Phase II chemical library for sodium iodide symporter (NIS) Inhibitors

EPA Science Inventory

In support of the Endocrine Disruptor Screening Program (EDSP), the U.S. EPA’s Office of Research and Development (ORD) is currently developing HTPS approaches to identify chemicals that may alter target sites in the thyroid hormone pathway. One target site is the sodium io...

Screening for Chemical Effects on Neuronal Proliferation and Neurite Outgrowth Using High-Content/High-Throughput Microscopy

EPA Science Inventory

The need to develop novel screening methods for developmental neurotoxicity in order to alleviate the demands of cost, time, and animals required for in vivo toxicity studies is well recognized. Accordingly, the U.S. EPA launched the ToxCast research program in 2007 to develop c...

Screening ToxCast™ Phase I Chemicals in a Mouse Embryonic Stem Cell Adherent Cell Differentiation and Cytotoxicity (ACDC) Assay

EPA Science Inventory

An Adherent Cell Differentiation and Cytotoxicity (ACDC) in vitro assay with mouse embryonic stem cells was used to screen the ToxCast Phase I chemical library for effects on cellular differentiation and cell number. The U.S. Environmental Protection Agency (EPA) established the ...

New Chemical/Biological Profiling and Informatics Approaches for Exploring Mutagenicity & Carcinogenicity: Updates of EPA ToxCast and Tox21 Programs

EPA Science Inventory

EPA’s National Center for Computational Toxicology is building capabilities to support a new paradigm for toxicity screening and prediction through harnessing of legacy toxicity data, creation of data linkages, and generation of new in vitro screening data. In association with EP...

Mechanical properties of thin films of laser-welded titanium and their associated welding defects.

PubMed

Wu, Yulu; Xin, Haitao; Zhang, Chunbao; Tang, Zhongbin; Zhang, Zhiyuan; Wang, Weifeng

2014-11-01

The aim of this study was to evaluate the mechanical properties of thin films of laser-welded cast titanium using an interference strain/displacement gauge (ISDG) and to analyze factors that affect laser welding. Dog-bone-shaped small specimens of cast titanium were prepared by wire cutting after they were laser-welded. The specimens were divided into three groups according to the gap distance of the laser weld; the control was non-welded titanium. Small specimens without cast defects detected by X-ray screening were measured by a tensile test machine using ISDG, and stress-strain curves were drawn. Finally, the fracture texture was analyzed. The ultimate tensile strengths (UTSs) of specimens with a gap distance of 0.00, 0.25, and 0.50 mm were 492.16 ± 33.19, 488.09 ± 43.18, and 558.45 ± 10.80 MPa, respectively. There were no significant differences in UTS between the test groups and the control group (p > 0.05). However, the plastic deformation and the percent elongation increased as the gap distance increased. Incomplete penetration defects appeared in groups that had small gap distances, which may have affected the properties of the laser-welded titanium. However, the welding material was still pure titanium. These results suggest that an appropriate gap distance should be maintained to improve the application of dental laser welding.

13. INTERIOR VIEW OF HILLMAN FAN HOUSE LOOKING NORTHEAST This ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. INTERIOR VIEW OF HILLMAN FAN HOUSE LOOKING NORTHEAST This view, taken in the southern airway, shows the circular brick-work surrounding the air intake, the cast iron shaft support, and one of the 1883 Guibal fan cast iron spiders. Three cast iron spiders support the ten feet by eleven feet wooden paddles. Remnants of the catwalk with its screen grating lead to the inner door of the airlock. Note also the support beams and reinforced concrete roof. The concrete floor of the airway has deteriorated. - Dorrance Colliery Fan Complex, South side of Susquehanna River at Route 115 & Riechard Street, Wilkes-Barre, Luzerne County, PA

Deposition of {open_quotes}unattached{close_quotes} radon daughters in models of human nasal and oral airways

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strong, J.C.; Swift, D.L.

In order to estimate accurately an effective dose equivalent for exposures to radon daughters, knowledge of their deposition in the lung is required. However, the nose and mouth are effective filters for removing aerosol particles, especially in the range of sizes of {open_quotes}unattached{close_quotes} radon daughters. Therefore, it is equally important to have reliable data on deposition in this region of the respiratory tract. We will describe our work in studying nasal and oral deposition of {open_quotes}unattached{close_quotes} radon daughters in casts of these airways. Several hollow casts of adult and child nasal and oral airways were fabricated at The John Hopkinsmore » University from layers of Perspect{trademark} (an acrylic plastic). The shapes of the airway passages were obtained from nuclear magnetic resonance sectional images of healthy subjects. The casts were exposed to radon gas and daughters produced by flushing filtered air through a commercially available {sup 226}Ra source. The gas stream was drawn through a 1.4-L cylindrical tube to allow measurable growth of {sup 218}Po activity before it was passed through casts of both nasal passages or the oral cavity. The deposition of {open_quotes}unattached{close_quotes} {sup 218}Po was measured by comparing the activity collected on filters mounted in series and in parallel with a cast. Measurements were made at various flow rates (Q; 4 to 20 L min{sup -1}). The diffusion coefficient (D) of {sup 218}Po was measured each time the flow rate was changed, by replacing the cast with a stainless steel gauze screen and measuring the activity penetrating the screen. The measured diffusion coefficient ranged from 0.02 to 0.05 cm{sup 2} s{sup -1} and was found to vary with the residence time of {sup 218}Po in the growth tube. The deposition efficiency ({eta}) of {sup 218}Po measured in these casts ranged from 50 to 70%, and was similar to values we found previously, using casts of nasal and oral airways from cadavers.« less

Analysis of Monolith Cores from an Engineering Scale Demonstration of a Prospective Cast Stone Process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crawford, C. L.; Cozzi, A. D.; Hill, K. A.

2016-06-01

The primary disposition path of Low Activity Waste (LAW) at the DOE Hanford Site is vitrification. A cementitious waste form is one of the alternatives being considered for the supplemental immobilization of the LAW that will not be treated by the primary vitrification facility. Washington River Protection Solutions (WRPS) has been directed to generate and collect data on cementitious or pozzolanic waste forms such as Cast Stone. This report documents the coring and leach testing of monolithic samples cored from an engineering-scale demonstration (ES Demo) with non-radioactive simulants. The ES Demo was performed at SRNL in October of 2013 usingmore » the Scaled Continuous Processing Facility (SCPF) to fill an 8.5 ft. diameter x 3.25 ft. high container with simulated Cast Stone grout. The Cast Stone formulation was chosen from the previous screening tests. Legacy salt solution from previous Hanford salt waste testing was adjusted to correspond to the average LAW composition generated from the Hanford Tank Waste Operation Simulator (HTWOS). The dry blend materials, ordinary portland cement (OPC), Class F fly ash, and ground granulated blast furnace slag (GGBFS or BFS), were obtained from Lafarge North America in Pasco, WA. In 2014 core samples originally obtained approximately six months after filling the ES Demo were tested along with bench scale molded samples that were collected during the original pour. A latter set of core samples were obtained in late March of 2015, eighteen months after completion of the original ES Demo. Core samples were obtained using a 2” diameter x 11” long coring bit. The ES Demo was sampled in three different regions consisting of an outer ring, a middle ring and an inner core zone. Cores from these three lateral zones were further segregated into upper, middle and lower vertical segments. Monolithic core samples were tested using the Environmental Protection Agency (EPA) Method 1315, which is designed to provide mass transfer rates (release rates) of inorganic analytes contained in monolithic material under diffusion controlled release conditions as a function of leaching time. Compressive strength measurements and drying tests were also performed on the 2015 samples. Leachability indices reported are based on analyte concentrations determined from dissolution of the dried samples.« less

Analysis of ToxCast data for food-relevant compounds by ...

EPA Pesticide Factsheets

The ToxCast program has generated a wealth of in vitro high throughput screening data, and best approaches for the interpretation and use of these data remain undetermined. We present case studies comparing the ToxCast and in vivo toxicity data for two food contact substances using the RISK21 approach. Available exposure data, toxicity data, and model predictions were analyzed for sodium pyrithione and dibutyltin dichloride. In-vitro to in-vivo extrapolation (IVIVE) was performed to determine oral equivalent doses (OEDs) for the ToxCast data bioactivity. For sodium pyrithione, calculated OEDs corresponded to doses that demonstrated toxicity in animal studies. For dibutyltin dichloride, calculated OEDs were below the doses that demonstrated toxicity in animals, but this was confounded by the conservative estimates used in the IVIVE calculations. These studies highlight the potential of the ToxCast approach while also indicating areas where additional data or predictive tools are needed. We present case studies comparing the ToxCast and in vivo toxicity data for two food contact substances using the RISK21 approach.

Clinical applications and implications of common and founder mutations in Indian subpopulations.

PubMed

Ankala, Arunkanth; Tamhankar, Parag M; Valencia, C Alexander; Rayam, Krishna K; Kumar, Manisha M; Hegde, Madhuri R

2015-01-01

South Asian Indians represent a sixth of the world's population and are a racially, geographically, and genetically diverse people. Their unique anthropological structure, prevailing caste system, and ancient religious practices have all impacted the genetic composition of most of the current-day Indian population. With the evolving socio-religious and economic activities of the subsects and castes, endogamous and consanguineous marriages became a commonplace. Consequently, the frequency of founder mutations and the burden of heritable genetic disorders rose significantly. Specifically, the incidence of certain autosomal-recessive disorders is relatively high in select Indian subpopulations and communities that share common recent ancestry. Although today clinical genetics and molecular diagnostic services are making inroads in India, the high costs associated with the technology and the tests often keep patients from an exact molecular diagnosis, making more customized and tailored tests, such as those interrogating the most common and founder mutations or those that cater to select sects within the population, highly attractive. These tests offer a quick first-hand affordable diagnostic and carrier screening tool. Here, we provide a comprehensive catalog of known common mutations and founder mutations in the Indian population and discuss them from a molecular, clinical, and historical perspective. © 2014 WILEY PERIODICALS, INC.

Strain Rate Dependency of Bronze Metal Matrix Composite Mechanical Properties as a Function of Casting Technique

NASA Astrophysics Data System (ADS)

Brown, Lloyd; Joyce, Peter; Radice, Joshua; Gregorian, Dro; Gobble, Michael

2012-07-01

Strain rate dependency of mechanical properties of tungsten carbide (WC)-filled bronze castings fabricated by centrifugal and sedimentation-casting techniques are examined, in this study. Both casting techniques are an attempt to produce a functionally graded material with high wear resistance at a chosen surface. Potential applications of such materials include shaft bushings, electrical contact surfaces, and brake rotors. Knowledge of strain rate-dependent mechanical properties is recommended for predicting component response due to dynamic loading or impact events. A brief overview of the casting techniques for the materials considered in this study is followed by an explanation of the test matrix and testing techniques. Hardness testing, density measurement, and determination of the volume fraction of WC particles are performed throughout the castings using both image analysis and optical microscopy. The effects of particle filling on mechanical properties are first evaluated through a microhardness survey of the castings. The volume fraction of WC particles is validated using a thorough density survey and a rule-of-mixtures model. Split Hopkinson Pressure Bar (SHPB) testing of various volume fraction specimens is conducted to determine strain dependence of mechanical properties and to compare the process-property relationships between the two casting techniques. The baseline performances of C95400 bronze are provided for comparison. The results show that the addition of WC particles improves microhardness significantly for the centrifugally cast specimens, and, to a lesser extent, in the sedimentation-cast specimens, largely because the WC particles are more concentrated as a result of the centrifugal-casting process. Both metal matrix composites (MMCs) demonstrate strain rate dependency, with sedimentation casting having a greater, but variable, effects on material response. This difference is attributed to legacy effects from the casting process, namely, porosity and localized WC particle grouping.

Application of ToxCast to evaluate potential biological effects ...

EPA Pesticide Factsheets

With the development of “high throughput” in-vitro biological assays, screening-level information on potential adverse biological effects is available for a rapidly increasing number of chemicals. The U.S. EPA ToxCast program has now evaluated several thousand chemicals with more than 800 assays. The original intent of this data was to evaluate potential for human health effects, but it is now being extended to environmental health evaluations. The R package ToxEval was developed as a screening tool to use ToxCast results for evaluation of potential adverse biological effects from trace organic chemicals in water samples. Using ToxEval, trace organic chemical data from water samples and passive samplers collected at 57 Great Lakes tributaries from 2010-2013 were examined to determine the tributaries with the greatest potential for adverse biological effects with prioritization of the most influential contaminants. Results are being used as part of the Great Lakes Restoration Initiative to focus current and future investigations that will help understand likely adverse outcome pathways in biological organisms, and to formulate possible remediation strategies. not applicable

Marginal Accuracy of Castings Fabricated with Ringless Casting Investment System and Metal Ring Casting Investment System: A Comparative Study.

PubMed

Kalavathi, M; Sachin, Bhuvana; Prasanna, B G; Shreeharsha, T V; Praveen, B; Ragher, Mallikarjuna

2016-02-01

The thermal expansion of the investment can be restricted by the metal casting ring because the thermal expansion of the ring is less than that of the investment. The ringless casting procedure is in use in clinical dentistry, though there is little scientific data to support its use in fixed partial dentures. In this study, marginal discrepancy of castings produced with the ringless casting technique and the conventional technique using the metal rings were compared. A total of 30 wax patterns were fabricated directly on a metal die. Optical stereomicroscope was used to measure the marginal discrepancy between the metal die and wax patterns. A total of 15 castings were invested using Bellavest T phosphate-bonded investment with the ringless technique and 15 were invested with the same investment with a metal ring; 30 castings were produced using a nickel-chromium ceramo-metal alloy. The internal surface of the castings was not modified and seated with finger pressure. The vertical marginal discrepancy was measured using an optical stereomicroscope at a magnification of 100x. The data obtained were statistically analyzed using students t-test (paired t-test and unpaired t-test). The castings of the ringless technique provided less vertical marginal discrepancy (240.56 ± 45.81 μ) than the castings produced with the conventional metal ring technique (281.98± 53.05 μ). The difference was statistically significant. The ringless casting technique had produced better marginal accuracy compared with conventional casting technique. Ringless casting system can be used routinely for clinical purpose.

Embryonic vascular disruption adverse outcomes: Linking high-throughput signaling signatures with functional consequences.

PubMed

Ellis-Hutchings, Robert G; Settivari, Raja S; McCoy, Alene T; Kleinstreuer, Nicole; Franzosa, Jill; Knudsen, Thomas B; Carney, Edward W

2017-04-13

Embryonic vascular disruption is an important adverse outcome pathway (AOP) as chemical disruption of cardiovascular development induces broad prenatal defects. High-throughput screening (HTS) assays aid AOP development although linking in vitro data to in vivo apical endpoints remains challenging. This study evaluated two anti-angiogenic agents, 5HPP-33 and TNP-470, across the ToxCastDB HTS assay platform and anchored the results to complex in vitro functional assays: the rat aortic explant assay (AEA), rat whole embryo culture (WEC), and the zebrafish embryotoxicity (ZET) assay. Both were identified as putative vascular disruptive compounds (pVDCs) in ToxCastDB and disrupted angiogenesis and embryogenesis in the functional assays. Differences were observed in potency and adverse effects: 5HPP-33 was embryolethal (WEC and ZET); TNP-470 produced caudal defects at lower concentrations. This study demonstrates how a tiered approach using HTS signatures and complex functional in vitro assays might be used to prioritize further in vivo developmental toxicity testing. Copyright © 2017 Elsevier Inc. All rights reserved.

Embryonic vascular disruption adverse outcomes: Linking high throughput signaling signatures with functional consequences.

PubMed

Ellis-Hutchings, Robert G; Settivari, Raja S; McCoy, Alene T; Kleinstreuer, Nicole; Franzosa, Jill; Knudsen, Thomas B; Carney, Edward W

2017-06-01

Embryonic vascular disruption is an important adverse outcome pathway (AOP) as chemical disruption of cardiovascular development induces broad prenatal defects. High throughput screening (HTS) assays aid AOP development although linking in vitro data to in vivo apical endpoints remains challenging. This study evaluated two anti-angiogenic agents, 5HPP-33 and TNP-470, across the ToxCastDB HTS assay platform and anchored the results to complex in vitro functional assays: the rat aortic explant assay (AEA), rat whole embryo culture (WEC), and the zebrafish embryotoxicity (ZET) assay. Both were identified as putative vascular disruptive compounds (pVDCs) in ToxCastDB and disrupted angiogenesis and embryogenesis in the functional assays. Differences were observed in potency and adverse effects: 5HPP-33 was embryolethal (WEC and ZET); TNP-470 produced caudal defects at lower concentrations. This study demonstrates how a tiered approach using HTS signatures and complex functional in vitro assays might be used to prioritize further in vivo developmental toxicity testing. Copyright © 2017 Elsevier Inc. All rights reserved.

Characterization of ToxCast Phase II compounds disruption of spontaneous network activity in cortical networks grown on multi-well microelectrode array (mwMEA) plates.

EPA Science Inventory

The development of multi-well microelectrode array (mwMEA) systems has increased in vitro screening throughput making them an effective method to screen and prioritize large sets of compounds for potential neurotoxicity. In the present experiments, a multiplexed approach was used...

An objective assessment of safety to drive in an upper limb cast.

PubMed

Stevenson, H L; Peterson, N; Talbot, C; Dalal, S; Watts, A C; Trail, I A

2013-03-01

Patients managed with upper limb cast immobilization often seek advice about driving. There is very little published data to assist in decision making, and advice given varies between healthcare professionals. There are no specific guidelines available from the UK Drivers and Vehicles Licensing Agency, police, or insurance companies. Evidence-based guidelines would enable clinicians to standardize the advice given to patients. Six individuals (three male, three female; mean age 36 years, range 27-43 years) were assessed by a mobility occupational therapist and driving standards agency examiner while completing a formal driving test in six different types of upper limb casts (above-elbow, below-elbow neutral, and below-elbow cast incorporating the thumb [Bennett's cast]) on both left and right sides. Of the 36 tests, participants passed 31 tests, suggesting that most people were able to safely drive with upper limb cast immobilization. However, driving in a left above-elbow cast was considered unsafe.

ToxCast Data Generation: Chemical Workflow

EPA Pesticide Factsheets

This page describes the process EPA follows to select chemicals, procure chemicals, register chemicals, conduct a quality review of the chemicals, and prepare the chemicals for high-throughput screening.

Evaluation of food-relevant chemicals in the ToxCast high-throughput screening program.

PubMed

Karmaus, Agnes L; Filer, Dayne L; Martin, Matthew T; Houck, Keith A

2016-06-01

Thousands of chemicals are directly added to or come in contact with food, many of which have undergone little to no toxicological evaluation. The landscape of the food-relevant chemical universe was evaluated using cheminformatics, and subsequently the bioactivity of food-relevant chemicals across the publicly available ToxCast highthroughput screening program was assessed. In total, 8659 food-relevant chemicals were compiled including direct food additives, food contact substances, and pesticides. Of these food-relevant chemicals, 4719 had curated structure definition files amenable to defining chemical fingerprints, which were used to cluster chemicals using a selforganizing map approach. Pesticides, and direct food additives clustered apart from one another with food contact substances generally in between, supporting that these categories not only reflect different uses but also distinct chemistries. Subsequently, 1530 food-relevant chemicals were identified in ToxCast comprising 616 direct food additives, 371 food contact substances, and 543 pesticides. Bioactivity across ToxCast was filtered for cytotoxicity to identify selective chemical effects. Initiating analyses from strictly chemical-based methodology or bioactivity/cytotoxicity-driven evaluation presents unbiased approaches for prioritizing chemicals. Although bioactivity in vitro is not necessarily predictive of adverse effects in vivo, these data provide insight into chemical properties and cellular targets through which foodrelevant chemicals elicit bioactivity. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

EPA DSSTox and ToxCast Project Updates: Generating New ...

EPA Pesticide Factsheets

EPA’s National Center for Computational Toxicology is generating data and capabilities to support a new paradigm for toxicity screening and prediction. The DSSTox project is improving public access to quality structure-annotated chemical toxicity information in less summarized forms than traditionally employed in SAR modeling, and in ways that facilitate data-mining and data read-across. The DSSTox Structure-Browser provides structure searchability across the full published DSSTox toxicity-related inventory, enables linkages to and from previously isolated toxicity data resources (soon to include public microarray resources GEO, ArrayExpress, and CEBS), and provides link-outs to cross-indexed public resources such as PubChem, ChemSpider, and ACToR. The published DSSTox inventory and bioassay information also have been integrated into PubChem allowing a user to take full advantage of PubChem structure-activity and bioassay clustering features. Phase I of the ToxCastTM project has generated high-throughput screening (HTS) data from several hundred biochemical and cell-based assays for a set of 320 chemicals, mostly pesticide actives, with rich toxicology profiles. DSSTox and ACToR are providing the primary cheminformatics support for ToxCastTM and collaborative efforts with the National Toxicology Program’s HTS Program and the NIH Chemical Genomics Center. DSSTox will also be a primary vehicle for publishing ToxCastTM ToxRef summarized bioassay data for use

Identification of candidate reference chemicals for in vitro steroidogenesis assays.

PubMed

Pinto, Caroline Lucia; Markey, Kristan; Dix, David; Browne, Patience

2018-03-01

The Endocrine Disruptor Screening Program (EDSP) is transitioning from traditional testing methods to integrating ToxCast/Tox21 in vitro high-throughput screening assays for identifying chemicals with endocrine bioactivity. The ToxCast high-throughput H295R steroidogenesis assay may potentially replace the low-throughput assays currently used in the EDSP Tier 1 battery to detect chemicals that alter the synthesis of androgens and estrogens. Herein, we describe an approach for identifying in vitro candidate reference chemicals that affect the production of androgens and estrogens in models of steroidogenesis. Candidate reference chemicals were identified from a review of H295R and gonad-derived in vitro assays used in methods validation and published in the scientific literature. A total of 29 chemicals affecting androgen and estrogen levels satisfied all criteria for positive reference chemicals, while an additional set of 21 and 15 chemicals partially fulfilled criteria for positive reference chemicals for androgens and estrogens, respectively. The identified chemicals included pesticides, pharmaceuticals, industrial and naturally-occurring chemicals with the capability to increase or decrease the levels of the sex hormones in vitro. Additionally, 14 and 15 compounds were identified as potential negative reference chemicals for effects on androgens and estrogens, respectively. These candidate reference chemicals will be informative for performance-based validation of in vitro steroidogenesis models. Copyright © 2017. Published by Elsevier Ltd.

Characterization of ToxCast Phase II compounds disruption of ...

EPA Pesticide Factsheets

The development of multi-well microelectrode array (mwMEA) systems has increased in vitro screening throughput making them an effective method to screen and prioritize large sets of compounds for potential neurotoxicity. In the present experiments, a multiplexed approach was used to determine compound effects on both neural function and cell health in primary cortical networks grown on mwMEA plates following exposure to ~1100 compounds from EPA’s Phase II ToxCast libraries. On DIV 13, baseline activity (40 min) was recorded prior to exposure to each compound at 40 µM. DMSO and the GABAA antagonist bicuculline (BIC) were included as controls on each mwMEA plate. Changes in spontaneous network activity (mean firing rate; MFR) and cell viability (lactate dehydrogenase; LDH and CellTiter Blue; CTB) were assessed within the same well following compound exposure. Activity calls (“hits”) were established using the 90th and 20th percentiles of the compound-induced change in MFR (medians of triplicates) across all tested compounds; compounds above (top 10% of compounds increasing MFR), and below (bottom 20% of compounds decreasing MFR) these thresholds, respectively were considered hits. MFR was altered beyond one of these thresholds by 322 compounds. Four compound categories accounted for 66% of the hits, including: insecticides (e.g. abamectin, lindane, prallethrin), pharmaceuticals (e.g. haloperidol, reserpine), fungicides (e.g. hexaconazole, fenamidone), and h

In silico study of in vitro GPCR assays by QSAR modeling ...

EPA Pesticide Factsheets

The U.S. EPA is screening thousands of chemicals of environmental interest in hundreds of in vitro high-throughput screening (HTS) assays (the ToxCast program). One goal is to prioritize chemicals for more detailed analyses based on activity in molecular initiating events (MIE) of adverse outcome pathways (AOPs). However, the chemical space of interest for environmental exposure is much wider than this set of chemicals. Thus, there is a need to fill data gaps with in silico methods, and quantitative structure-activity relationships (QSARs) are a proven and cost effective approach to predict biological activity. ToxCast in turn provides relatively large datasets that are ideal for training and testing QSAR models. The overall goal of the study described here was to develop QSAR models to fill the data gaps in a larger environmental database of ~32k structures. The specific aim of the current work was to build QSAR models for 18 G-Protein Coupled Receptor (GPCR) assays, part of the aminergic category. Two QSAR modeling strategies were adopted: classification models were developed to separate chemicals into active/non-active classes, and then regression models were built to predict the potency values of the bioassays for the active chemicals. Multiple software programs were used to calculate constitutional, topological and substructural molecular descriptors from two-dimensional (2D) chemical structures. Model-fitting methods included PLSDA (partial least squares d

Secondary Waste Cast Stone Waste Form Qualification Testing Plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Westsik, Joseph H.; Serne, R. Jeffrey

2012-09-26

The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is being constructed to treat the 56 million gallons of radioactive waste stored in 177 underground tanks at the Hanford Site. The WTP includes a pretreatment facility to separate the wastes into high-level waste (HLW) and low-activity waste (LAW) fractions for vitrification and disposal. The LAW will be converted to glass for final disposal at the Integrated Disposal Facility (IDF). Cast Stone – a cementitious waste form, has been selected for solidification of this secondary waste stream after treatment in the ETF. The secondary-waste Cast Stone waste form must be acceptablemore » for disposal in the IDF. This secondary waste Cast Stone waste form qualification testing plan outlines the testing of the waste form and immobilization process to demonstrate that the Cast Stone waste form can comply with the disposal requirements. Specifications for the secondary-waste Cast Stone waste form have not been established. For this testing plan, Cast Stone specifications are derived from specifications for the immobilized LAW glass in the WTP contract, the waste acceptance criteria for the IDF, and the waste acceptance criteria in the IDF Permit issued by the State of Washington. This testing plan outlines the testing needed to demonstrate that the waste form can comply with these waste form specifications and acceptance criteria. The testing program must also demonstrate that the immobilization process can be controlled to consistently provide an acceptable waste form product. This testing plan also outlines the testing needed to provide the technical basis for understanding the long-term performance of the waste form in the disposal environment. These waste form performance data are needed to support performance assessment analyses of the long-term environmental impact of the secondary-waste Cast Stone waste form in the IDF« less

Effect of Casting Material on the Cast Pressure After Sequential Cast Splitting.

PubMed

Roberts, Aaron; Shaw, K Aaron; Boomsma, Shawn E; Cameron, Craig D

2017-01-01

Circumferential casting is a vital component of nonoperative fracture management. These casts are commonly valved to release pressure and decrease the risk of complications from swelling. However, little information exists regarding the effect of different casting supplies on the pressure within the cast. Seventy-five long-arm casts were performed on human volunteers, divided between 5 experimental groups with 15 casts in each groups. Testing groups consisted of 2 groups with a plaster short-arm cast overwrapped with fiberglass to a long arm with either cotton or synthetic cast padding. The 3 remaining groups included fiberglass long-arm casts with cotton, synthetic, or waterproof cast padding. A pediatric blood pressure cuff bladder was placed within the cast and inflated to 100 mm Hg. After inflation, the cast was sequentially released with pressure reading preformed after each stage. Order of release consisted of cast bivalve, cast padding release, and cotton stockinet release. After release, the cast was overwrapped with a loose elastic bandage. Difference in pressure readings were compared based upon the cast material. Pressures within the cast were found to decrease with sequential release of cast. The cast type had no effect of change in pressure. Post hoc testing demonstrated that the type of cast padding significantly affected the cast pressures with waterproof padding demonstrating the highest pressure readings at all time-points in the study, followed by synthetic padding. Cotton padding had the lowest pressure readings at all time-points. Type of cast padding significantly influences the amount of pressure within a long-arm cast, even after bivalving the cast and cutting the cast padding. Cotton cast padding allows for the greatest change in pressure. Cotton padding demonstrates the greatest change in pressure within a long-arm cast after undergoing bivalve. Synthetic and waterproof cast padding should not be used in the setting of an acute fracture to accommodate swelling.

In honor of the Teratology Society's 50th anniversary: The role of Teratology Society members in the development and evolution of in vivo developmental toxicity test guidelines.

PubMed

Tyl, Rochelle W

2010-06-01

Members of the Teratology Society (established in 1960) were involved in the first governmental developmental and reproductive toxicity testing guidelines (1966) by FDA following the thalidomide epidemic, followed by other national and international governmental testing guidelines. The Segment II (developmental toxicity) study design, described in rodents and rabbits, has evolved with additional enhanced endpoints and better descriptions, mechanistic insights, range-finding studies, and toxico/pharmacokinetic ADME information (especially for pharmaceuticals). Society members were also involved in the development of the current screening assays and tests for endocrine disruptors (beginning in 1996) and are now involved with developing new testing guidelines (e.g., the extended one-generation protocol), and evaluating the current test guidelines and new initiatives under ILSI/HESI sponsorship. New initiatives include ToxCast from the U.S. EPA to screen, prioritize, and predict toxic chemicals by high throughput and high-content in vitro assays, bioinformation, and modeling to reduce (or eliminate) in vivo whole animal studies. Our Society and its journal have played vital roles in the scientific and regulatory accomplishments in birth defects research over the past 50 years and will continue to do so in the future. Happy 50th anniversary! (c) 2010 Wiley-Liss, Inc.

Full-arch implant fixed prostheses: a comparative study on the effect of connection type and impression technique on accuracy of fit.

PubMed

Papaspyridakos, Panos; Hirayama, Hiroshi; Chen, Chun-Jung; Ho, Chung-Han; Chronopoulos, Vasilios; Weber, Hans-Peter

2016-09-01

The aim of this study was to assess the effect of connection type and impression technique on the accuracy of fit of implant-supported fixed complete-arch dental prostheses (IFCDPs). An edentulous mandibular cast with five implants was fabricated to serve as master cast (control) for both implant- and abutment-level baselines. A titanium one-piece framework for an IFCDP was milled at abutment level and used for accuracy of fit measurements. Polyether impressions were made using a splinted and non-splinted technique at the implant and abutment level leading to four test groups, n = 10 each. Hence, four groups of test casts were generated. The impression accuracy was evaluated indirectly by assessing the fit of the IFCDP framework on the generated casts of the test groups, clinically and radiographically. Additionally, the control and all test casts were digitized with a high-resolution reference scanner (IScan D103i, Imetric, Courgenay, Switzerland) and standard tessellation language datasets were generated and superimposed. Potential correlations between the clinical accuracy of fit data and the data from the digital scanning were investigated. To compare the accuracy of casts of the test groups versus the control at the implant and abutment level, Fisher's exact test was used. Of the 10 casts of test group I (implant-level splint), all 10 presented with accurate clinical fit when the framework was seated on its respective cast, while only five of 10 casts of test group II (implant-level non-splint) showed adequate fit. All casts of group III (abutment-level splint) presented with accurate fit, whereas nine of 10 of the casts of test group IV (abutment-level non-splint) were accurate. Significant 3D deviations (P < 0.05) were found between group II and the control. No statistically significant differences were found between groups I, III, and IV compared with the control. Implant connection type (implant level vs. abutment level) and impression technique did affect the 3D accuracy of implant impressions only with the non-splint technique (P < 0.05). For one-piece IFCDPs, the implant-level splinted impression technique showed to be more accurate than the non-splinted approach, whereas at the abutment-level, no difference in the accuracy was found. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

78 FR 13835 - Harmonization of Airworthiness Standards-Miscellaneous Structures Requirements

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-01

... requirements for critical and non-critical castings; add control system requirements that consider structural... of critical casting and Quality control, inspection, and testing requirements for critical and non... control, inspection, and testing requirements for critical and non-critical castings. The proposed rule...

Cast Fe-base cylinder/regenerator housing alloy

NASA Technical Reports Server (NTRS)

Larson, F.; Kindlimann, L.

1980-01-01

The development of an iron-base alloy that can meet the requirements of automotive Stirling engine cylinders and regenerator housings is described. Alloy requirements are as follows: a cast alloy, stress for 5000-hr rupture life of 200 MPa (29 ksi) at 775 C (1427 F), oxidation/corrosion resistance comparable to that of N-155, compatibility with hydrogen, and an alloy cost less than or equal to that of 19-9DL. The preliminary screening and evaluation of ten alloys are described.

Determining the Mechanical Properties of Lattice Block Structures

NASA Technical Reports Server (NTRS)

Wilmoth, Nathan

2013-01-01

Lattice block structures and shape memory alloys possess several traits ideal for solving intriguing new engineering problems in industries such as aerospace, military, and transportation. Recent testing at the NASA Glenn Research Center has investigated the material properties of lattice block structures cast from a conventional aerospace titanium alloy as well as lattice block structures cast from nickel-titanium shape memory alloy. The lattice block structures for both materials were sectioned into smaller subelements for tension and compression testing. The results from the cast conventional titanium material showed that the expected mechanical properties were maintained. The shape memory alloy material was found to be extremely brittle from the casting process and only compression testing was completed. Future shape memory alloy lattice block structures will utilize an adjusted material composition that will provide a better quality casting. The testing effort resulted in baseline mechanical property data from the conventional titanium material for comparison to shape memory alloy materials once suitable castings are available.

Aluminum-fly ash metal matrix composites for automotive parts. [Reports for October 1 to December 1998, and January 31 to March 31, 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, David; Purgert, Robert; Rhudy, Richard

1999-04-21

Some highlights are: (1) Material development, process development, and part validation are occurring simultaneously on a fast track schedule. (2) Prior project activity has resulted in a program emphasis on three components--manifolds, mounting brackets, and motor mounts; and three casting techniques--squeeze casting, pressure die casting, and sand casting. (3) With the project focus, it appears possible to offer manifolds and mounting brackets for automotive qualification testing on a schedule in line with the PNGV Year 2004 goal. (4) Through an iterative process of fly ash treatment, MMC ingot preparation, foundry process refinement, and parts production, both foundries (Eck Industries andmore » Thompson Aluminum Casting Company) are addressing the pre-competitive issues of: (a) Optimum castability with fly ash shapes and sizes; (b) Best mechanical properties derived from fly ash shapes and sizes; (c) Effective fly ash classification processes; (d) Mechanical properties resulting from various casting processes and fly ash formulations. Eck and TAC continued experiments with batch ingot provided by both Eck and the University of Wisconsin at Milwaukee. Castings were run that contained varying amounts of fly ash and different size fractions. Components were cast using cenosphere material to ascertain the effects of squeeze casting and to determine whether the pressure would break the cenospheres. Test parts are currently being machined into substandard test bars for mechanical testing. Also, the affect of heat treatments on ashalloy are being studied through comparison to two lots, one heat treated and one in the ''as cast'' condition.« less

Effect of bionic coupling units' forms on wear resistance of gray cast iron under dry linear reciprocating sliding condition

NASA Astrophysics Data System (ADS)

Pang, Zuobo; Zhou, Hong; Xie, Guofeng; Cong, Dalong; Meng, Chao; Ren, Luquan

2015-07-01

In order to get close to the wear form of guide rails, the homemade linear reciprocating wear testing machine was used for the wear test. In order to improve the wear-resistance of gray cast iron guide rail, bionic coupling units of different forms were manufactured by a laser. Wear behavior of gray-cast-iron with bionic-coupling units has been studied under dry sliding condition at room temperature using the wear testing machine. The wear resistance was evaluated by means of weight loss measurement and wear morphology. The results indicated that bionic coupling unit could improve the wear resistance of gray cast iron. The wear resistance of gray cast iron with reticulation bionic coupling unit is the best. When the load and speed changed, reticulation bionic coupling unit still has excellent performance in improving the wear resistance of gray cast iron.

AMCC casting development, volume 2

NASA Technical Reports Server (NTRS)

1995-01-01

PCC successfully cast and performed nondestructive testing, FPI and x-ray, on seventeen AMCC castings. Destructive testing, lab analysis and chemical milling, was performed on eleven of the castings and the remaining six castings were shipped to NASA or Aerojet. Two of the six castings shipped, lots 015 and 016, were fully processed per blueprint requirements. PCC has fully developed the gating and processing parameters of this part and feels the part could be implemented into production, after four more castings have been completed to ensure the repeatability of the process. The AMCC casting has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or thermal gradient control. This method of setting up thermal gradients in the casting during solidification represents a significant process improvement for PCC and has been successfully implemented on other programs. The alloy, JBK75, is a relatively new alloy in the investment casting arena and required our engineering staff to learn the gating, processing, and dimensional characteristics of the material.

Comparison and Analysis of Toxcast Data with In Vivo Data for ...

EPA Pesticide Factsheets

The ToxCast program has generated a great wealth of in vitro high throughput screening (HTS) data on a large number of compounds, providing a unique resource of information on the bioactivity of these compounds. However, analysis of these data are ongoing, and interpretation and use of the ToxCast data such as for safety assessment of food related compounds remains undetermined. To fill this gap, we conducted a case study of 2 food-related compounds to better understand the ToxCast data and its potential use in chemical safety assessment by comparison between ToxCast and traditional, in vivo toxicology data using the Risk21 approach. Risk21 is an exposure driven flexible risk assessment framework developed by ILSI HESI. Prior work (Karmaus et. al., 2016) looking at all food-relevant compounds in ToxCast showed that food contact substances had high bioactivity in ToxCast assays. To better understand these chemicals based on their indirect food use, exposure and availability of traditional toxicology data, two compounds, dibutyltin dichloride and sodium pyrithione, were selected from a list of the food contact substances with the greatest activity in ToxCast. Exposure and hazard data were compiled and analyzed for both compounds. Comparison between in vitro HTS and in vivo data for sodium pyrithione showed that concentrations that elicited bioactivity in ToxCast assays corresponded to low- and no- observed adverse effect doses in animals. For dibutyltin dichlori

Concise Associated Symptoms Tracking scale: a brief self-report and clinician rating of symptoms associated with suicidality.

PubMed

Trivedi, Madhukar H; Wisniewski, Stephen R; Morris, David W; Fava, Maurizio; Kurian, Benji T; Gollan, Jackie K; Nierenberg, Andrew A; Warden, Diane; Gaynes, Bradley N; Luther, James F; Rush, A John

2011-06-01

US Food and Drug Administration (FDA) warnings recommend monitoring negative symptoms associated with the initiation of antidepressant medications as these symptoms may interfere with full recovery and pose safety concerns. There is currently no brief, reliable rating instrument for assessing treatment-emergent, negative symptoms. We evaluated the psychometric properties of 2 versions of the newly developed 17-item Concise Associated Symptom Tracking (CAST) scale, the CAST Clinician Rating (CAST-C) and CAST Self-Rated (CAST-SR), which are brief instruments designed to measure the 5 relevant associated symptom domains (irritability, anxiety, mania, insomnia, and panic). The study enrolled 265 outpatients with major depressive disorder (MDD), from July 2007 through February 2008, into an 8-week, open-label trial with a selective serotonin reuptake inhibitor. Diagnosis of MDD was determined by the Psychiatric Diagnostic Screening questionnaire and an MDD checklist based on DSM-IV-TR criteria. Suicidality (suicidal ideation with associated behaviors) is 1 of 9 symptoms of MDD (depressed mood, loss of interest, appetite or weight change, sleep disturbance, reduced concentration or indecisiveness, fatigue or decreased energy, psychomotor agitation or retardation, feelings of worthlessness or excessive guilt). Psychometric evaluations were conducted on both versions of the CAST. Cronbach α was .80 (CAST-C) and .81 (CAST-SR). Factor analysis identified 5 factors for each scale: (1) irritability, (2) anxiety, (3) mania, (4) insomnia, and (5) panic. When the item that cross-loaded on 2 factors was eliminated, the 16-item solution had a better goodness of fit (CAST-C: 0.90 vs 0.87; CAST-SR: 0.88 vs 0.84). Cronbach α for the 16-item versions was .77 (CAST-C) and .78 (CAST-SR). The 5 associated CAST symptom domains correlated well with other standard measures of these domains. The 16-item CAST-C and CAST-SR demonstrated excellent psychometric properties. These are potentially useful measures for monitoring treatment-emergent negative symptoms associated with antidepressants, as recommended by the FDA. Clinicaltrials.gov Identifier: NCT00532103. © Copyright 2011 Physicians Postgraduate Press, Inc.

Use of high-throughput and in vivo data to support read ...

EPA Pesticide Factsheets

Disrupting normal function of mitochondria can culminate in a variety of organ-level toxicities. A number of mechanisms - such as uncoupling of oxidative phosphorylation and inhibition of the electron transport chain - have been implicated in mitochondrial toxicity. The presence of mitochondrial toxicity has led to a number of drugs being withdrawn from the market highlighting the need to identify potential mitochondrial toxicants within the environment. High-throughput screening (HTS) assays provide a means of rapidly gathering toxicity data for a large number of chemicals; however, information as to the associated in vivo effect is typically unknown. The Adverse Outcome Pathway (AOP) concept provides a valuable scaffold onto which mechanistic data from different levels of biological organisation can be arranged.Information pertaining to mitochondrial toxicity from the U.S. EPA’s ToxCast program were integrated with rodent in vivo data from U.S. EPA’s ToxRefDB to connect the high throughput ToxCast assay results with potential adverse outcome data. Previously developed structural alerts were utilized to profile the chemicals with both in vitro mitochondrial toxicity and in vivo rodent data. Structural similarity guided by the toxicity profile as measured in the ToxCast assay battery was then used to group those chemicals which either were not tested in a mitochondrial toxicity assay or were not considered a “hit” and read-across was performed. Subsequen

An Evaluation of ToxCast Angiogenic Disruptors for Effects on ...

EPA Pesticide Factsheets

Angiogenesis is a critical developmental process and a potential target for chemical teratogenesis. Over one-tenth of the Tox21 library of 10,000 compounds have been shown to disrupt mitochondrial function [Attene-Ramos et al., 2015]. Previous studies utilizing ToxCast chemicals have shown a correlation between vascular disruption in Tg(kdrl:EGFP)mitfab692 zebrafish embryos and mitochondrial disruption reported in literature [McCollum et al., submitted]. To more closely examine this correlation, we culled ToxCast data for mitochondrial translocator protein (TSPO; NovaScreen) and mitochondrial membrane potential (MMP) and biomass (Tox21 and Apredica) for a total of 192 chemicals tested for adverse effects on vascular development in transgenic zebrafish embryos [McCollum et al., submitted; Tal et al., submitted]. This set included 40 compounds that disrupted vascular development in zebrafish embryos (zVDC) and 152 compounds that did not. The zVDC set displayed consistent in vitro bioactivity on mitochondrial membrane potential (with a Pearson Chi-Square value of 16.92, p < 0.0001), but did not have consistent effects on mitochondrial biomass (0.4; p = 0.527) or translocator protein ligand binding (0.05; p = 0.823). The effect on MMP is consistent with the hypothesis that disruption of the mitochondrial respiratory complexes is a potential mode of action of angiogenic disruptors (complex I for pyridaben, fenpyroxymate, tebufenpyrad, and rotenone; complex III for py

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serne, R. Jeffrey; Westsik, Joseph H.; Williams, Benjamin D.

This report describes the results from long-term laboratory leach tests performed at Pacific Northwest National Laboratory (PNNL) for Washington River Protection Solutions (WRPS) to evaluate the release of key constituents from monoliths of Cast Stone prepared with four simulated low-activity waste (LAW) liquid waste streams. Specific objectives of the Cast Stone long-term leach tests described in this report focused on four activities: 1. Extending the leaching times for selected ongoing EPA-1315 tests on monoliths made with LAW simulants beyond the conventional 63-day time period up to 609 days reported herein (with some tests continuing that will be documented later) inmore » an effort to evaluate long-term leaching properties of Cast Stone to support future performance assessment activities. 2. Starting new EPA-1315 leach tests on archived Cast Stone monoliths made with four LAW simulants using two leachants (deionized water [DIW] and simulated Hanford Integrated Disposal Facility (IDF) Site vadose zone pore water [VZP]). 3. Evaluating the impacts of varying the iodide loading (starting iodide concentrations) in one LAW simulant (7.8 M Na Hanford Tank Waste Operations Simulator (HTWOS) Average) by manufacturing new Cast Stone monoliths and repeating the EPA-1315 leach tests using DIW and the VZP leachants. 4. Evaluating the impacts of using a non-pertechnetate form of Tc that is present in some Hanford tanks. In this activity one LAW simulant (7.8 M Na HTWOS Average) was spiked with a Tc(I)-tricarbonyl gluconate species and then solidified into Cast Stone monoliths. Cured monoliths were leached using the EPA-1315 leach protocol with DIW and VZP. The leach results for the Tc-Gluconate Cast Stone monoliths were compared to Cast Stone monoliths pertechnetate.« less

Deducing material quality in cast and hot-forged steels by new bending test

NASA Astrophysics Data System (ADS)

Valberg, Henry; Langøy, Morten; Nedreberg, Mette; Helvig, Torgeir

2017-10-01

A special bend test has been developed and applied for the purpose of characterization and comparison of the material ductility in crankpin steel discs manufactured by casting, or casting subsequently followed by hot open-die forging (ODF) or closed-die forging (CDF). The bending test specimen consists of a small rectangular plate of material with a round hole cut out in the middle. The "eye-shape" specimens were cut out from various positions either near to the surface of, or from the interior of the discs. The test method revealed differences in ductility for the investigated materials, and for different depth positions inside the discs. The roughening of the specimen surface on the top-side of the specimen bend also varied dependent on the processing method for the material. Current results show that this test method is useful for evaluation of material quality in differently processed material. Experimental bend test results are presented for differently processed variants of the same material, i.e., crankpin discs either made by solely casting or casting subsequently followed by hot working either by ODF or CDF.

ToxCast Phase I

EPA Pesticide Factsheets

Background: Chemical toxicity testing is being transformed by advances in biology and computer modeling, concerns over animal use and the thousands of environmental chemicals lacking toxicity data. EPA's ToxCast program aims to address these concerns by screening and prioritizing chemicals for potential human toxicity using in vitro assays and in silico approaches. Objectives: This project aims to evaluate the use of in vitro assays for understanding the types of molecular and pathway perturbations caused by environmental chemicals and to build initial prioritization models of in vivo toxicity. Methods: We tested 309 mostly pesticide active chemicals in 467 assays across 9 technologies, including high-throughput cell-free assays and cell-based assays in multiple human primary cells and cell lines, plus rat primary hepatocytes. Both individual and composite scores for effects on genes and pathways were analyzed. Results: Chemicals display a broad spectrum of activity at the molecular and pathway levels. Many expected interactions are seen, including endocrine and xenobiotic metabolism enzyme activity. Chemicals range in promiscuity across pathways, from no activity to affecting dozens of pathways. We find a statistically significant inverse association between the number of pathways perturbed by a chemical at low in vitro concentrations and the lowest in vivo dose at which a chemical causes toxicity. We also find associations between a small set in vitro ass

Hot forging of roll-cast high aluminum content magnesium alloys

NASA Astrophysics Data System (ADS)

Kishi, Tomohiro; Watari, Hisaki; Suzuki, Mayumi; Haga, Toshio

2017-10-01

This paper reports on hot forging of high aluminum content magnesium alloy sheets manufactured using horizontal twin-roll casting. AZ111 and AZ131 were applied for twin-roll casting, and a hot-forging test was performed to manufacture high-strength magnesium alloy components economically. For twin-roll casting, the casting conditions of a thick sheet for hot forging were investigated. It was found that twin-roll casting of a 10mm-thick magnesium alloy sheet was possible at a roll speed of 2.5m/min. The grain size of the cast strip was 50 to 70µm. In the hot-forging test, blank material was obtained from as-cast strip. A servo press machine with a servo die cushion was used to investigate appropriate forging conditions (e.g., temperature, forging load, and back pressure) for twin-roll casts (TRCs) AZ111 and AZ131. It was determined that high aluminum content magnesium alloy sheets manufactured using twin-roll casting could be forged with a forging load of 150t and a back pressure of 3t at 420 to 430°C. Applying back pressure during hot forging effectively forged a pin-shaped product.

Integrative data mining of high-throughput in vitro screens, in vivo data, and disease information to identify Adverse Outcome Pathway (AOP) signatures:ToxCast high-throughput screening data and Comparative Toxicogenomics Database (CTD) as a case study.

EPA Science Inventory

The Adverse Outcome Pathway (AOP) framework provides a systematic way to describe linkages between molecular and cellular processes and organism or population level effects. The current AOP assembly methods however, are inefficient. Our goal is to generate computationally-pr...

Grain Boundary Engineering the Mechanical Properties of Allvac 718Plus(Trademark) Superalloy

NASA Technical Reports Server (NTRS)

Gabb, Timothy P.; Telesman, Jack; Garg, Anita; Lin, Peter; Provenzano, virgil; Heard, Robert; Miller, Herbert M.

2010-01-01

Grain Boundary Engineering can enhance the population of structurally-ordered "low S" Coincidence Site Lattice (CSL) grain boundaries in the microstructure. In some alloys, these "special" grain boundaries have been reported to improve overall resistance to corrosion, oxidation, and creep resistance. Such improvements could be quite beneficial for superalloys, especially in conditions which encourage damage and cracking at grain boundaries. Therefore, the effects of GBE processing on high-temperature mechanical properties of the cast and wrought superalloy Allvac 718Plus (Allvac ATI) were screened. Bar sections were subjected to varied GBE processing, and then consistently heat treated, machined, and tested at 650 C. Creep, tensile stress relaxation, and dwell fatigue crack growth tests were performed. The influences of GBE processing on microstructure, mechanical properties, and associated failure modes are discussed.

Profound differences in fat versus carbohydrate preferences in CAST/EiJ and C57BL/6J mice: Role of fat taste.

PubMed

Sclafani, Anthony; Vural, Austin S; Ackroff, Karen

2018-06-19

In a nutrient self-selection study, CAST/EiJ mice consumed more carbohydrate than fat while C57BL/6J (B6) mice showed the opposite preference. The present study revealed similar strain differences in preferences for isocaloric fat (Intralipid) and carbohydrate (sucrose, maltodextrin) solutions in chow-fed mice. In initial 2-day choice tests, percent fat intakes of CAST and B6 mice were 4-9% and 71-81% respectively. In subsequent nutrient vs. water tests, CAST mice consumed considerably less fat but not carbohydrate compared to B6 mice. Orosensory rather than postoral factors are implicated in the very low fat preference and intake of CAST mice. This is supported by results of a choice test with Intralipid mixed with non-nutritive sweeteners vs. non-sweet maltodextrin. The preference of CAST mice for sweetened fat exceeded that of B6 mice (94 vs. 74%) and absolute fat intakes were similar in the two strains. When given unsweetened Intralipid vs. water tests at ascending fat concentrations CAST mice displayed reduced fat preferences at 0.1-5% and reduced intakes at 0.5-5% concentrations, compared to B6 mice. The differential fat preferences of CAST and C57BL/6 mice may reflect differences in fat taste sensing or in central neural processes related to fat selection. Copyright © 2017. Published by Elsevier Inc.

Characterization and Evaluation of Incorporation the Casting Sand in Mortar

NASA Astrophysics Data System (ADS)

Zanelato, E. B.; Azevedo, A. R. G.; Alexandre, J.; Xavier, C. G.; Monteiro, S. N.; Mendonça, T. A. O.

The process of casting metals and alloys occurs through the fusion of this metal and its subsequent casting into a mold with the dimensions and geometry close to the final piece. Most foundries use sand casting molds for making you. This work aims to characterize and evaluate the foundry sand to allow its use in segments of Civil Engineering, creating a viable destination for a residue is that discarded. The following characterization tests were performer: particle size, chemical analysis, X-ray Diffraction and Density Real grain. For the execution of the test specimens was used to 1:3 cement and sand, and the incorporation of 10% and 20% of the total mass replacing the sand, and the trace reference. The results show that best results in compression and bending tests were obtained by replacing 10 % of common sand for sand casting.

Low-cost single-crystal turbine blades, volume 2

NASA Technical Reports Server (NTRS)

Strangman, T. E.; Dennis, R. E.; Heath, B. R.

1984-01-01

The overall objectives of Project 3 were to develop the exothermic casting process to produce uncooled single-crystal (SC) HP turbine blades in MAR-M 247 and higher strength derivative alloys and to validate the materials process and components through extensive mechanical property testing, rig testing, and 200 hours of endurance engine testing. These Program objectives were achieved. The exothermic casting process was successfully developed into a low-cost nonproperietary method for producing single-crystal castings. Single-crystal MAR-M 247 and two derivatives DS alloys developed during this project, NASAIR 100 and SC Alloy 3, were fully characterized through mechanical property testing. SC MAR-M 247 shows no significant improvement in strength over directionally solidified (DS) MAR-M 247, but the derivative alloys, NASAIR 100 and Alloy 3, show significant tensile and fatigue improvements. Firtree testing, holography, and strain-gauge rig testing were used to determine the effects of the anisotropic characteristics of single-crystal materials. No undesirable characteristics were found. In general, the single-crystal material behaved similarly to DS MAR-M 247. Two complete engine sets of SC HP turbine blades were cast using the exothermic casting process and fully machined. These blades were successfully engine-tested.

Evaluation of the three-dimensional accuracy of implant impression techniques in two simulated clinical conditions by optical scanning.

PubMed

Sabouhi, Mahmoud; Bajoghli, Farshad; Abolhasani, Majid

2015-01-01

The success of an implant-supported prosthesis is dependent on the passive fit of its framework fabricated on a precise cast. The aim of this in vitro study was to digitally compare the three-dimensional accuracy of implant impression techniques in partially and completely edentulous conditions. The master model simulated two clinical conditions. The first condition was a partially edentulous mandibular arch with an anterior edentulous space (D condition). Two implant analogs were inserted in bilateral canine sites. After elimination of the teeth, the model was converted to a completely edentulous condition (E condition). Three different impression techniques were performed (open splinted [OS], open unsplinted [OU], closed [C]) for each condition. Six groups of casts (DOS, DOU, DC, EOS, EOU, EC) (n = 8), totaling 48 casts, were made. Two scan bodies were secured onto the master edentulous model and onto each test cast and digitized by an optical scanning system. The related scans were superimposed, and the mean discrepancy for each cast was determined. The statistical analysis showed no significant difference in the accuracy of casts as a function of model status (P = .78, analysis of variance [ANOVA] test), impression technique (P = .57, ANOVA test), or as the combination of both (P = .29, ANOVA test). The distribution of data was normal (Kolmogorov-Smirnov test). Model status (dentate or edentulous) and impression technique did not influence the precision of the casts. There is no difference among any of the impression techniques in either simulated clinical condition.

Casting made simple using modified sprue design: an in vitro study.

PubMed

Baskaran, B Eswaran; Geetha Prabhu, K R; Prabhu, R; Krishna, G Phani; Eswaran, M A; Gajapathi, B

2014-01-01

Success in dental casting restorations for fixed partial dentures (FPDs) depends on the castability. Castability is described as the ability of an alloy to faithfully reproduce sharp detail and fine margins of a wax pattern. The goal of a prosthodontist is to provide the patient with restorations that fit precisely. Regardless of the alloy used for casting, the casting technique should yield a casted alloy, which should possess sufficient mass, surface hardness and minimal porosity after casting. Twenty patterns for casting were made from three-dimensional printed resin pattern simulating a 3 unit FPD and casted using modified sprue technique. Later test samples were cemented sequentially on stainless steel model using pressure indicating paste and evaluated for vertical marginal gap in eight predetermined reference areas. Marginal gap were measured in microns using Video Measuring System (VMS2010F-CIP Corporation, Korea). A portion of the axial wall of the cast abutments depicting premolar and molar were sectioned and embedded in acrylic resin and tested for micro hardness using Reichert Polyvar 2 Met Microhardness tester (Reichert, Austria) and porosity using Quantimet Image Analyzer (Quantimet Corporation London, England). The results obtained for marginal gap, micro hardness, and porosity of all test samples were tabulated, descriptive statistics were calculated and the values were found to be within the clinically acceptable range. The new sprue technique can be an alternative and convenient method for casting which would minimize metal wasting and less time consuming. However, further studies with same technique on various parameters are to be conducted for its broad acceptance.

14 CFR 29.621 - Casting factors.

Code of Federal Regulations, 2011 CFR

2011-01-01

... established. (3) For castings procured to a specification that guarantees the mechanical properties of the material in the casting and provides for demonstration of these properties by test of coupons cut from the...

14 CFR 27.621 - Casting factors.

Code of Federal Regulations, 2010 CFR

2010-01-01

... established. (3) For castings procured to a specification that guarantees the mechanical properties of the material in the casting and provides for demonstration of these properties by test of coupons cut from the...

14 CFR 29.621 - Casting factors.

Code of Federal Regulations, 2010 CFR

2010-01-01

... established. (3) For castings procured to a specification that guarantees the mechanical properties of the material in the casting and provides for demonstration of these properties by test of coupons cut from the...

14 CFR 27.621 - Casting factors.

Code of Federal Regulations, 2011 CFR

2011-01-01

... established. (3) For castings procured to a specification that guarantees the mechanical properties of the material in the casting and provides for demonstration of these properties by test of coupons cut from the...

21st century tools to prioritize contaminants for monitoring and management

EPA Science Inventory

The webinar focused on ways that ToxCast high throughput screening data and the adverse outcome pathway framework, under development in the CSS program, can be used to prioritize environmental contaminants for monitoring and management.

Screening for celiac disease in patients with osteoporosis.

PubMed

Legroux-Gérot, Isabelle; Leloire, Olivier; Blanckaert, Franck; Tonnel, François; Grardel, Bruno; Ducrocq, Jean-Louis; Cortet, Bernard

2009-03-01

Whether patients with osteoporosis should be screened for celiac disease is controversial. The objective of this study was to measure the prevalence of asymptomatic celiac disease in a cohort of patients with osteoporosis. We studied 140 patients (133 postmenopausal women and 7 men) aged 40-75 years (mean age, 62.9+/-9.4 years) with primary osteoporosis diagnosed by absorptiometry (spine or hip T-score <-2.5SD). We routinely measured serum and urinary calcium, serum phosphate, alkaline phosphatase, 25-OH-vitamin D3, and IgG and IgA antigliadin antibodies. Patients with positive antigliadin antibody tests were tested for antitransglutaminase antibodies. A history of fractures were noted in 52 (37%) patients, with 57 peripheral and 54 vertebral fractures overall. Vitamin D deficiency was found in 60 (43%) patients. IgG antigliadin antibodies were positive in 11 (8%) patients, IgA antigliadin antibodies in 11 (8%) patients, and both antibodies in 4 (3%) patients. Antitransglutaminase antibodies were negative in all patients. No significant differences in laboratory test or absorptiometry results were found between patients with versus without IgA antigliadin antibodies. The T-score at the spine was nonsignificantly lower in patients with than without IgG antigliadin antibodies (-3.17+/-0.49 and -2.82+/-0.77, P=0.076). We found no excess risk of celiac disease in our cohort of patients with osteoporosis. Despite the small sample size, our results cast doubt on the need for celiac-disease screening in osteoporotic patients who have no gastrointestinal symptoms.

Marginal accuracy of nickel chromium copings fabricated by conventional and accelerated casting procedures, produced with ringless and metal ring investment procedures: A comparative in vitro study.

PubMed

Alex, Deepa; Shetty, Y Bharath; Miranda, Glynis Anita; Prabhu, M Bharath; Karkera, Reshma

2015-01-01

Conventional investing and casting techniques are time-consuming and usually requires 2-4 h for completion. Accelerated nonstandard, casting techniques have been reported to achieve similar quality results in significantly less time, namely, in 30-40 min. During casting, it is essential to achieve compensation for the shrinkage of solidifying alloy by investment expansion. The metal casting ring restricts the thermal expansion of investment because the thermal expansion of the ring is lesser than that of the investment. The use of casting ring was challenged with the introduction of the ringless technique. A total of 40 test samples of nickel chromium (Ni-Cr) cast copings were obtained from the patterns fabricated using inlay casting wax. The 20 wax patterns were invested using metal ring and 20 wax patterns were invested using the ringless investment system. Of both the groups, 10 samples underwent conventional casting, and the other 10 underwent accelerated casting. The patterns were casted using the induction casting technique. All the test samples of cast copings were evaluated for vertical marginal gaps at four points on the die employing a stereo optical microscope. The vertical marginal discrepancy data obtained were tabulated. Mean and standard deviations were obtained. Vertical discrepancies were analyzed using analysis of variance and Tukey honestly significantly different. The data obtained were found to be very highly significant (P < 0.001). Mean vertical gap was the maximum for Group II (53.64 μm) followed by Group IV (47.62 μm), Group I (44.83 μm) and Group III (35.35 μm). The Ni-Cr cast copings fabricated with the conventional casting using ringless investment system showed significantly better marginal fit than that of cast copings fabricated from conventional and accelerated casting with metal ring investment and accelerated casting using ringless investment since those copings had shown the least vertical marginal discrepancies among the four methods evaluated in this study.

Use of high-throughput in vitro toxicity screening data in cancer hazard evaluations by IARC Monograph Working Groups

PubMed Central

Chiu, Weihsueh A.; Guyton, Kathryn Z.; Martin, Matthew T.; Reif, David M.; Rusyn, Ivan

2017-01-01

Evidence regarding carcinogenic mechanisms serves a critical role in International Agency for Research on Cancer (IARC) Monograph evaluations. Three recent IARC Working Groups pioneered inclusion of the US Environmental Protection Agency (EPA) ToxCast program high-throughput screening (HTS) data to supplement other mechanistic evidence. In Monograph V110, HTS profiles were compared between perfluorooctanoic acid (PFOA) and prototypical activators across multiple nuclear receptors. For Monograph V112 -113, HTS assays were mapped to 10 key characteristics of carcinogens identified by an IARC expert group, and systematically considered as an additional mechanistic data stream. Both individual assay results and ToxPi-based rankings informed mechanistic evaluations. Activation of multiple nuclear receptors in HTS assays showed that PFOA targets peroxisome proliferator activated and other receptors. ToxCast assays substantially covered 5 of 10 key characteristics, corroborating literature evidence of “induces oxidative stress” and “alters cell proliferation, cell death or nutrient supply” and filling gaps for “modulates receptor-mediated effects.” Thus, ToxCast HTS data were useful both in evaluating specific mechanistic hypotheses and in the overall evaluation of mechanistic evidence. However, additional HTS assays are needed to provide more comprehensive coverage of the 10 key characteristics of carcinogens that form the basis of current IARC mechanistic evaluations. PMID:28738424

Use of high-throughput in vitro toxicity screening data in cancer hazard evaluations by IARC Monograph Working Groups.

PubMed

Chiu, Weihsueh A; Guyton, Kathryn Z; Martin, Matthew T; Reif, David M; Rusyn, Ivan

2018-01-01

Evidence regarding carcinogenic mechanisms serves a critical role in International Agency for Research on Cancer (IARC) Monograph evaluations. Three recent IARC Working Groups pioneered inclusion of the US Environmental Protection Agency (EPA) ToxCast program high-throughput screening (HTS) data to supplement other mechanistic evidence. In Monograph V110, HTS profiles were compared between perfluorooctanoic acid (PFOA) and prototypical activators across multiple nuclear receptors. For Monograph V112-113, HTS assays were mapped to 10 key characteristics of carcinogens identified by an IARC expert group, and systematically considered as an additional mechanistic data stream. Both individual assay results and ToxPi-based rankings informed mechanistic evaluations. Activation of multiple nuclear receptors in HTS assays showed that PFOA targets not only peroxisome proliferator activated receptors, but also other receptors. ToxCast assays substantially covered 5 of 10 key characteristics, corroborating literature evidence of "induces oxidative stress" and "alters cell proliferation, cell death or nutrient supply" and filling gaps for "modulates receptor-mediated effects." Thus, ToxCast HTS data were useful both in evaluating specific mechanistic hypotheses and in contributing to the overall evaluation of mechanistic evidence. However, additional HTS assays are needed to provide more comprehensive coverage of the 10 key characteristics of carcinogens that form the basis of current IARC mechanistic evaluations.

Final Report, Volume 2, The Development of Qualification Standards for Cast Duplex Stainless Steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Steven, W.; Lundin, Carl, W.

2005-09-30

The scope of testing cast Duplex Stainless Steel (DSS) required testing to several ASTM specifications, while formulating and conducting industry round robin tests to verify and study the reproducibility of the results. ASTM E562 (Standard Test Method for Determining Volume Fraction by Systematic manual Point Count) and ASTM A923 (Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels) were the specifications utilized in conducting this work. An ASTM E562 industry round robin, ASTM A923 applicability study, ASTM A923 industry round robin, and an ASTM A923 study of the effectiveness of existing foundry solution annealing proceduresmore » for producing cast DSS without intermetallic phases were implemented. In the ASTM E562 study, 5 samples were extracted from various cast austenitic and DSS in order to have varying amounts of ferrite. Each sample was metallographically prepared by UT and sent to each of 8 participants for volume fraction of ferrite measurements. Volume fraction of ferrite was measured using manual point count per ASTM E562. FN was measured from the Feritescope® and converted to volume fraction of ferrite. Results indicate that ASTM E562 is applicable to DSS and the results have excellent lab-to-lab reproducibility. Also, volume fraction of ferrite conversions from the FN measured by the Feritescope® were similar to volume fraction of ferrite measured per ASTM E562. In the ASTM A923 applicability to cast DSS study, 8 different heat treatments were performed on 3 lots of ASTM A890-4A (CD3MN) castings and 1 lot of 2205 wrought DSS. The heat treatments were selected to produce a wide range of cooling rates and hold times in order to study the suitability of ASTM A923 to the response of varying amounts on intermetallic phases [117]. The test parameters were identical to those used to develop ASTM A923 for wrought DSS. Charpy V-notch impact samples were extracted from the castings and wrought DSS and tested per ASTM A923 method B (Charpy impact test). Method A (sodium hydroxide etch test) was performed on one half of a fractured Charpy V-notch impact sample and Method C (ferric chloride corrosion weight loss test) was performed on another half. Test results for the three cast lots and one wrought lot indicate that ASTM A923 is relevant for detecting intermetallic phases in cast DSS. In the ASTM A923 round robin study, five laboratories conducted ASTM A923 Methods A & C on cast DSS material and the lab-to-lab reproducibility of the data was determined. Two groups of samples were sent to the participants. Group 1 samples were tested per ASTM A923 Method A, group 2 samples were tested by ASTM A923 Method C. Testing procedures for this round robin study were identical to those used in the ASTM A923 applicability study. Results from this round robin indicate that there is excellent lab-to-lab reproducibility of ASTM A923 with respect to cast DSS and that ASTM A923 could be expanded to cover both wrought and cast DSS. In the ASTM A923 study of the effectiveness of existing foundry solution annealing procedures for producing cast DSS without intermetallic phases, Ten heats of ASTM A890-4A (CD3MN) in the foundry solution annealed condition were tested per ASTM A923 Methods A, B, & C. Testing of these materials per ASTM A923 was used to determine if the foundry solution anneal procedures were adequate to completely eliminate any intermetallic phases, which may have precipitated during the casting and subsequent heat treatment processes. All heats showed no sign of intermetallic phase per Method A, passed minimum Charpy impact energy requirements per Method B (> 40 ft-lbs @ -40°C (-40°F)), and showed negligible weight loss per Method C (< 10 mdd). These results indicate that the solution annealing procedure used by foundries is adequate to produce a product free from intermetallic phases.« less

Final Report, Volume 2, The Development of Qualification Standards for Cast Duplex Stainless Steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Steven, W.; Lundin, Carl, D.

2005-09-30

The scope of testing cast Duplex Stainless Steel (DSS) required testing to several ASTM specifications, while formulating and conducting industry round robin tests to verify and study the reproducibility of the results. ASTM E562 (Standard Test Method for Determining Volume Fraction by Systematic manual Point Count) and ASTM A923 (Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels) were the specifications utilized in conducting this work. An ASTM E562 industry round robin, ASTM A923 applicability study, ASTM A923 industry round robin, and an ASTM A923 study of the effectiveness of existing foundry solution annealing proceduresmore » for producing cast DSS without intermetallic phases were implemented. In the ASTM E562 study, 5 samples were extracted from various cast austenitic and DSS in order to have varying amounts of ferrite. Each sample was metallographically prepared by UT and sent to each of 8 participants for volume fraction of ferrite measurements. Volume fraction of ferrite was measured using manual point count per ASTM E562. FN was measured from the Feritescope{reg_sign} and converted to volume fraction of ferrite. Results indicate that ASTM E562 is applicable to DSS and the results have excellent lab-to-lab reproducibility. Also, volume fraction of ferrite conversions from the FN measured by the Feritescope{reg_sign} were similar to volume fraction of ferrite measured per ASTM E562. In the ASTM A923 applicability to cast DSS study, 8 different heat treatments were performed on 3 lots of ASTM A890-4A (CD3MN) castings and 1 lot of 2205 wrought DSS. The heat treatments were selected to produce a wide range of cooling rates and hold times in order to study the suitability of ASTM A923 to the response of varying amounts on intermetallic phases [117]. The test parameters were identical to those used to develop ASTM A923 for wrought DSS. Charpy V-notch impact samples were extracted from the castings and wrought DSS and tested per ASTM A923 method B (Charpy impact test). Method A (sodium hydroxide etch test) was performed on one half of a fractured Charpy V-notch impact sample and Method C (ferric chloride corrosion weight loss test) was performed on another half. Test results for the three cast lots and one wrought lot indicate that ASTM A923 is relevant for detecting intermetallic phases in cast DSS. In the ASTM A923 round robin study, five laboratories conducted ASTM A923 Methods A & C on cast DSS material and the lab-to-lab reproducibility of the data was determined. Two groups of samples were sent to the participants. Group 1 samples were tested per ASTM A923 Method A, group 2 samples were tested by ASTM A923 Method C. Testing procedures for this round robin study were identical to those used in the ASTM A923 applicability study. Results from this round robin indicate that there is excellent lab-to-lab reproducibility of ASTM A923 with respect to cast DSS and that ASTM A923 could be expanded to cover both wrought and cast DSS. In the ASTM A923 study of the effectiveness of existing foundry solution annealing procedures for producing cast DSS without intermetallic phases, Ten heats of ASTM A890-4A (CD3MN) in the foundry solution annealed condition were tested per ASTM A923 Methods A, B, & C. Testing of these materials per ASTM A923 was used to determine if the foundry solution anneal procedures were adequate to completely eliminate any intermetallic phases, which may have precipitated during the casting and subsequent heat treatment processes. All heats showed no sign of intermetallic phase per Method A, passed minimum Charpy impact energy requirements per Method B (> 40 ft-lbs {at} -40 C (-40 F)), and showed negligible weight loss per Method C (< 10 mdd). These results indicate that the solution annealing procedure used by foundries is adequate to produce a product free from intermetallic phases.« less

[Effect of preparation methods on the metal-porcelain bond strength of Co-Cr alloys].

PubMed

Liu, Jie; Chi, Shuai; Xu, Jin; Wang, Yanyan; Zhan, Desong

2014-04-01

To compare the shear bond strength(SBS) of cast Co-Cr alloys and selective laser melting(SLM) Co-Cr alloys with those of dental porcelain. A dental porcelain (Vita) was applied on cast and SLM Co-Cr alloy specimens (n = 10). SBS test was conducted, and fracture mode analysis was determined. Student's t-test by SPSS 13.0 software was employed to analyze the data. The SLM Co-Cr alloy specimens had lower SBS values than the cast Co-Cr alloy specimens (P > 0.05). The metal-porcelain bond strength value of the cast group was (33.11 +/- 4.98) MPa, and that of the SLM group was (30.94 +/- 5.98) MPa. The specimens in both test groups exhibited mixed failure. The metal-porcelain system processed by SLM exhibit a bond strength that is similar to that of the cast group. This system also display a high precision.

Tensile and creep rupture properties of (16) uncoated and (2) coated engineering alloys at elevated temperatures

NASA Technical Reports Server (NTRS)

Fritz, L. J.; Koster, W. P.

1977-01-01

Sixteen test materials were supplied by NASA-Lewis Research Center as wrought bar or cast remelt stock. The cast remelt stock was cast into test blanks with two such materials being also evaluated after Jocoat coating was applied. Mechanical properties evaluated included tensile, modulus of elasticity, Poisson's Ratio, creep properties and creep rupture strength. Tests were conducted at temperatures applicable to the service temperature of the various alloys. This range extended from room temperature to 1000 C.

Solidification Based Grain Refinement in Steels

DTIC Science & Technology

2011-09-27

project (Tasks 7-9). An industrial trial on an investment casting was done using rare earth silicide additions in a furnace prior to pouring (Task 7...an investment casting was done using rare earth silicide additions in a furnace prior to pounng (la.sk 7). Some of the test parts had a finer...poured at the end of a six casting batch. One test tree with no RE addition was poured. Before the second test tree was poured, sufficient RE silicide was

Effect of Heating Time on Hardness Properties of Laser Clad Gray Cast Iron Surface

NASA Astrophysics Data System (ADS)

Norhafzan, B.; Aqida, S. N.; Mifthal, F.; Zulhishamuddin, A. R.; Ismail, I.

2018-03-01

This paper presents effect of heating time on cladded gray cast iron. In this study, the effect of heating time on cladded gray cast iron and melted gray cast iron were analysed. The gray cast iron sample were added with mixed Mo-Cr powder using laser cladding technique. The mixed Mo and Cr powder was pre-placed on gray cast iron surface. Modified layer were sectioned using diamond blade cutter and polish using SiC abrasive paper before heated. Sample was heated in furnace for 15, 30 and 45 minutes at 650 °C and cool down in room temperature. Metallographic study was conduct using inverted microscope while surface hardness properties were tested using Wilson hardness test with Vickers scale. Results for metallographic study showed graphite flakes within matrix of pearlite. The surface hardness for modified layer decreased when increased heating time process. These findings are significant to structure stability of laser cladded gray cast iron with different heating times.

Optimization of Squeeze Casting for Aluminum Alloy Parts

DOE Office of Scientific and Technical Information (OSTI.GOV)

David Schwam; John F. Wallace; Qingming Chang

2002-07-30

This study was initiated with the installation of a new production size UBE 350 Ton VSC Squeeze Casting system in the Metal Casting Laboratory at Case Western University. A Lindberg 75k W electrical melting furnace was installed alongside. The challenge of installation and operation of such industrial-size equipment in an academic environment was met successfully. Subsequently, a Sterling oil die heater and a Visi-Track shot monitoring system were added. A significant number of inserts were designed and fabricated over the span of the project, primarily for squeeze casting different configurations of test bars and plates. A spiral ''ribbon insert'' formore » evaluation of molten metal fluidity was also fabricated. These inserts were used to generate a broad range of processing conditions and determine their effect on the quality of the squeeze cast parts. This investigation has studied the influence of the various casting variables on the quality of indirect squeeze castings primarily of aluminum alloys. The variables studied include gating design, fill time and fill patter, metal pressure and die temperature variations. The quality of the die casting was assessed by an analysis of both their surface condition and internal soundness. The primary metal tested was an aluminum 356 alloy. In addition to determining the effect of these casting variables on casting quality as measured by a flat plate die of various thickness, a number of test bar inserts with different gating designs have been inserted in the squeeze casting machine. The mechanical properties of these test bars produced under different squeeze casting conditions were measured and reported. The investigation of the resulting properties also included an analysis of the microstructure of the squeeze castings and the effect of the various structural constituents on the resulting properties. The main conclusions from this investigation are as follows: The ingate size and shape are very important since it must remain open until the casting is solidified and pressure is maintained on the solidifying casting. Fanned gates, particularly on the smaller section castings avoid jetting effects at the ingate end. The fan type ingate helps accomplish a rapid fill without high velocities. The molten metal has to fill the cavity before localized solidification occurs. This is best accomplished with a larger ingate to attain rapid filling without excessive velocity or jetting that occurs at high metal velocities. Straight gates are prone to case jetting of the metal stream even a low velocities. Fanned gates allow use of higher fill velocity without excessive jetting. A higher metal pressure provides a more complete fill of the die including improved compensation for solidification shrinkage. With the proper filling pattern, ingates, overflows and die temperature for a given die, very good tensile properties can be attained in squeeze casting. In general, the smaller squeeze castings require higher die temperatures. Computer models using the UES Procast and MagmaSoft finite element software can, after suitable adjustments, predict the flow pattern in the die cavity.« less

Crew Autonomous Scheduling Test (CAST)

NASA Image and Video Library

2017-07-18

iss052e016190 (July 18, 2017) --- Astronaut Peggy Whitson is photographed sitting in front of the Cupola windows during the final Crew Autonomous Scheduling Test (CAST) session. The CAST investigation analyzes whether crews can develop plans in a reasonable period of time with appropriate input, whether proximity of planners to the planned operations increases efficiency, and if crew members are more satisfied when given a role in plan development.

Feasibility of a Braided Composite for Orthopedic Bone Cast

PubMed Central

Evans, Katherine R; Carey, Jason P

2013-01-01

A tubular braided composite bone cast for improving the efficiency and quality of bone fracture treatment is investigated. Finite element analysis was used to evaluate stress concentrations in fracture sites supported with plate and tubular casts. The stress in a plated bone is 768 % of that in a whole bone at the same location, while it is only 47 % in a bone with a tubular cast. Three unbroken synthetic humeri were mechanically tested using an in-vitro long bone testing procedure developed in-house to find their stiffness at 20° and 60° abduction; these were found to be 116.8 ± 1.5 N/mm and 20.63 ± 0.02 N/mm, respectively. A 2 cm gap osteotomy was cut through the diaphysis in each bone. The bones were casted with a Kevlar/Cold cure composite, with calculated braid angles and thicknesses that Closely matched bone propoerties. The stiffness tests were repeated, and the results were within 10 % of the unbroken bone. This novel method of bone casting is promising if other clinical challenges can be minimized. PMID:23459455

Low-cost single-crystal turbine blades, volume 1

NASA Technical Reports Server (NTRS)

Strangman, T. E.; Heath, B.; Fujii, M.

1983-01-01

The exothermic casting process was successfully developed into a low cost nonproprietary method for producing single crystal (SC) castings. Casting yields were lower than expected, on the order of 20 percent, but it is felt that the casting yield could be significantly improved with minor modifications to the process. Single crystal Mar-M 247 and two derivative SC alloys were developed. NASAIR 100 and SC Alloy 3 were fully characterized through mechanical property testing. SC Mar-M 247 shows no significant improvement in strength over directionally solidified (DS) Mar-M 247, but the derivative alloys, NASAIR 100 and Alloy 3, show significant tensile and fatigue improvements. The 1000 hr/238 MPa (20 ksi) stress rupture capability compared to DS Mar-M 247 was improved over 28 C. Firtree testing, holography, and strain gauge rig testing were used to evaluate the effects of the anisotropic characteristics of single crystal materials. In general, the single crystal material behaved similarly to DS Mar-M 247. Two complete engine sets of SC HP turbine blades were cast using the exothermic casting process and fully machined.

Feasibility of a braided composite for orthopedic bone cast.

PubMed

Evans, Katherine R; Carey, Jason P

2013-01-01

A tubular braided composite bone cast for improving the efficiency and quality of bone fracture treatment is investigated. Finite element analysis was used to evaluate stress concentrations in fracture sites supported with plate and tubular casts. The stress in a plated bone is 768 % of that in a whole bone at the same location, while it is only 47 % in a bone with a tubular cast. Three unbroken synthetic humeri were mechanically tested using an in-vitro long bone testing procedure developed in-house to find their stiffness at 20° and 60° abduction; these were found to be 116.8 ± 1.5 N/mm and 20.63 ± 0.02 N/mm, respectively. A 2 cm gap osteotomy was cut through the diaphysis in each bone. The bones were casted with a Kevlar/Cold cure composite, with calculated braid angles and thicknesses that Closely matched bone propoerties. The stiffness tests were repeated, and the results were within 10 % of the unbroken bone. This novel method of bone casting is promising if other clinical challenges can be minimized.

Application of Rapid Prototyping to the Investment Casting of Test Hardware (MSFC Center Director's Discretionary Fund Final Report, Project No. 98-08)

NASA Technical Reports Server (NTRS)

Cooper, K. G.; Wells, D.

2000-01-01

Investment casting masters of a selected propulsion hardware component, a fuel pump housing, were rapid prototyped on the several processes in-house, along with the new Z-Corp process acquired through this project. Also, tensile samples were prototyped and cast using the same significant parameters. The models were then shelled in-house using a commercial grade zircon-based slurry and stucco technique. Next, the shelled models were fired and cast by our in-house foundry contractor (IITRI), with NASA-23, a commonly used test hardware metal. The cast models are compared by their surface finish and overall appearance (i.e., the occurrence of pitting, warping, etc.), as well as dimensional accuracy.

In vitro screening for potential chemical inhibitors of ...

EPA Pesticide Factsheets

Control of thyroid hormone (TH) signaling in vertebrates is dependent upon multiple key events including iodide uptake, hormone synthesis, metabolism and elimination, to maintain proper homeostasis of the hormones. Deiodinase enzymes interconvert THs between less active and more active forms via release of iodide from the substrate hormones. The activity of deiodinases has been identified as an important endpoint to include in the context of screening chemicals for thyroid hormone disruption. To address the lack of data regarding the potential for chemicals to inhibit these enzymes a research effort was initially focused on human deiodinase type 1 (D1). We utilized an adenovirus expression system for production of D1 enzyme, established robust assay parameters for non-radioactive determination of iodide release by the Sandell-Kolthoff method, and employed a 96-well plate format for screening chemical libraries. An initial set of 19 chemicals was used to establish the assay. Included in this set was the known D1 inhibitor 6-propylthiouracil (used as a positive control). Over 1800 unique chemicals primarily from the EPA’s ToxCast phase 1_v2, phase 2, and e1K chemical libraries were tested in the screening assay. Chemicals were initially screened at a single high concentration of 200 µM to identify potential D1 inhibitors. The majority of the chemicals did not inhibit D1 activity in this initial screen as defined as a response of less than 20% inhibition c

Resistance to High-Temperature Oxidation and Wear of Various Ferrous Alloys Used in Rolling Mills

NASA Astrophysics Data System (ADS)

Delaunois, Fabienne; Stanciu, Victor Ioan; Sinnaeve, Mario

2018-03-01

Various materials are commonly used to manufacture work rolls for hot rolling mills, such as ICDP (Indefinite Chill Double Pour) cast irons, high-chromium white cast irons, and high speed steels (HSS). Various chemical compositions and microstructures are studied in order to optimize the in-use behavior of those grades of rolls. In this paper, six grades of ferrous alloys (an ICDP cast iron; an ICDP cast iron enriched in vanadium, niobium, and molybdenum; a HSS; a graphitic HSS; a high-chromium white cast iron (Hi-Cr); and a niobium-molybdenum-doped high-chromium white cast iron) were investigated. High-temperature oxidation tests with gravimetric means at 575 °C in water vapor atmosphere and sliding wear tests were carried out. The oxidation kinetics was followed during oxidation test. The microstructure was observed by optical and scanning electron microscopies. The oxides formed on the surface of the samples were analyzed by XRD and EDS. The thickness of the oxide scales and the mass gain were measured after oxidation test. The results showed that the behavior of all the grades differed. The oxide scale of HSS and HSS-G grades was fine and their friction coefficient was low. The weight gain after oxidation test of HSS was high. Hi-Cr and M-Hi-Cr grades presented highly porous oxide layer and an important increase of the friction coefficient during wear test. ICDP and M-ICDP had intermediate behavior.

Engineering scale demonstration of a prospective Cast Stone process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cozzi, A.; Fowley, M.; Hansen, E.

2014-09-30

This report documents an engineering-scale demonstration with non-radioactive simulants that was performed at SRNL using the Scaled Continuous Processing Facility (SCPF) to fill an 8.5 ft container with simulated Cast Stone grout. The Cast Stone formulation was chosen from the previous screening tests. Legacy salt solution from previous Hanford salt waste testing was adjusted to correspond to the average composition generated from the Hanford Tank Waste Operation Simulator (HTWOS). The dry blend materials, ordinary portland cement (OPC), Class F fly ash, and ground granulated blast furnace slag (GGBFS or BFS), were obtained from Lafarge North America in Pasco, WA. Overmore » three days, the SCPF was used to fill a 1600 gallon container, staged outside the facility, with simulated Cast Stone grout. The container, staged outside the building approximately 60 ft from the SCPF, was instrumented with x-, y-, and z-axis thermocouples to monitor curing temperature. The container was also fitted with two formed core sampling vials. For the operation, the targeted grout production rate was 1.5 gpm. This required a salt solution flow rate of approximately 1 gpm and a premix feed rate of approximately 580 lb/h. During the final day of operation, the dry feed rate was increased to evaluate the ability of the system to handle increased throughput. Although non-steady state operational periods created free surface liquids, no bleed water was observed either before or after operations. The final surface slope at a fill height of 39.5 inches was 1-1.5 inches across the 8.5 foot diameter container, highest at the final fill point and lowest diametrically opposed to the fill point. During processing, grout was collected in cylindrical containers from both the mixer discharge and the discharge into the container. These samples were stored in a humid environment either in a closed box proximal to the container or inside the laboratory. Additional samples collected at these sampling points were analyzed for rheological properties and density. Both the rheological properties (plastic viscosity and yield strength) and density were consistent with previous and later SCPF runs.« less

Accurate detection of low prevalence AKT1 E17K mutation in tissue or plasma from advanced cancer patients

PubMed Central

de Bruin, Elza C.; Whiteley, Jessica L.; Corcoran, Claire; Kirk, Pauline M.; Fox, Jayne C.; Armisen, Javier; Lindemann, Justin P. O.; Schiavon, Gaia; Ambrose, Helen J.; Kohlmann, Alexander

2017-01-01

Personalized healthcare relies on accurate companion diagnostic assays that enable the most appropriate treatment decision for cancer patients. Extensive assay validation prior to use in a clinical setting is essential for providing a reliable test result. This poses a challenge for low prevalence mutations with limited availability of appropriate clinical samples harboring the mutation. To enable prospective screening for the low prevalence AKT1 E17K mutation, we have developed and validated a competitive allele-specific TaqMan® PCR (castPCR™) assay for mutation detection in formalin-fixed paraffin-embedded (FFPE) tumor tissue. Analysis parameters of the castPCR™ assay were established using an FFPE DNA reference standard and its analytical performance was assessed using 338 breast cancer and gynecological cancer FFPE samples. With recent technical advances for minimally invasive mutation detection in circulating tumor DNA (ctDNA), we subsequently also evaluated the OncoBEAM™ assay to enable plasma specimens as additional diagnostic opportunity for AKT1 E17K mutation testing. The analysis performance of the OncoBEAM™ test was evaluated using a novel AKT1 E17K ctDNA reference standard consisting of sheared genomic DNA spiked into human plasma. Both assays are employed at centralized testing laboratories operating according to quality standards for prospective identification of the AKT1 E17K mutation in ER+ breast cancer patients in the context of a clinical trial evaluating the AKT inhibitor AZD5363 in combination with endocrine (fulvestrant) therapy. PMID:28472036

Measuring cannabis consumption: Psychometric properties of the Daily Sessions, Frequency, Age of Onset, and Quantity of Cannabis Use Inventory (DFAQ-CU).

PubMed

Cuttler, Carrie; Spradlin, Alexander

2017-01-01

We created the Daily Sessions, Frequency, Age of Onset, and Quantity of Cannabis Use Inventory (DFAQ-CU) because the current lack of psychometrically sound inventories for measuring these dimensions of cannabis use has impeded research on the effects of cannabis in humans. A sample of 2,062 cannabis users completed the DFAQ-CU and was used to assess the DFAQ-CU's factor structure and reliability. To assess validity, a subsample of 645 participants completed additional measures of cannabis dependence and problems (Marijuana Smoking History Questionnaire [MSHQ], Timeline Followback [TLFB], Cannabis Abuse Screening Test [CAST], Cannabis Use Disorders Identification Test Revised [CUDIT-R], Cannabis Use Problems Identification Test [CUPIT], and Alcohol Use Disorder Identification Test [AUDIT]). A six-factor structure was revealed, with factors measuring: daily sessions, frequency, age of onset, marijuana quantity, cannabis concentrate quantity, and edibles quantity. The factors were reliable, with Cronbach's alpha coefficients ranging from .69 (daily sessions) to .95 (frequency). Results further provided evidence for the factors' convergent (MSHQ, TLFB), predictive (CAST, CUDIT-R, CUPIT), and discriminant validity (AUDIT). The DFAQ-CU is the first psychometrically sound inventory for measuring frequency, age of onset, and quantity of cannabis use. It contains pictures of marijuana to facilitate the measurement of quantity of marijuana used, as well as questions to assess the use of different forms of cannabis (e.g., concentrates, edibles), methods of administering cannabis (e.g., joints, hand pipes, vaporizers), and typical THC levels. As such, the DFAQ-CU should help facilitate research on frequency, quantity, and age of onset of cannabis use.

Development and Implementation of the Casting of Rods Made of Refractory Cast Alloys

NASA Astrophysics Data System (ADS)

Kabanov, I. V.; Urin, S. L.; Ivanyuk, A. S.; Nesterov, A. N.; Bogdanov, S. V.

2017-12-01

The problems of the production of a so-called casting rod blank made of a refractory casting alloy in the vacuum induction furnaces of AO Metallurgical Plant Electrostal are considered. A unique technology of casting and subsequent treatment of as-cast rod blanks made of refractory alloys is developed, tested, and optimized. As a result of the developed and performed measures for the production of metal products in the Consarc furnace, the ingot-to-product yield increases by 15% as compared to metal casting in an ISV-1.0 furnace. As a result, we have widened the range of cast alloy grades and are going to cast metals for the manufacture of blanks of other sizes and ranges of alloy an steel grades.

Comparative Evaluation of Conventional and Accelerated Castings on Marginal Fit and Surface Roughness.

PubMed

Jadhav, Vivek Dattatray; Motwani, Bhagwan K; Shinde, Jitendra; Adhapure, Prasad

2017-01-01

The aim of this study was to evaluate the marginal fit and surface roughness of complete cast crowns made by a conventional and an accelerated casting technique. This study was divided into three parts. In Part I, the marginal fit of full metal crowns made by both casting techniques in the vertical direction was checked, in Part II, the fit of sectional metal crowns in the horizontal direction made by both casting techniques was checked, and in Part III, the surface roughness of disc-shaped metal plate specimens made by both casting techniques was checked. A conventional technique was compared with an accelerated technique. In Part I of the study, the marginal fit of the full metal crowns as well as in Part II, the horizontal fit of sectional metal crowns made by both casting techniques was determined, and in Part III, the surface roughness of castings made with the same techniques was compared. The results of the t -test and independent sample test do not indicate statistically significant differences in the marginal discrepancy detected between the two casting techniques. For the marginal discrepancy and surface roughness, crowns fabricated with the accelerated technique were significantly different from those fabricated with the conventional technique. Accelerated casting technique showed quite satisfactory results, but the conventional technique was superior in terms of marginal fit and surface roughness.

High Throughput Assays and Exposure Science (ISES annual meeting)

EPA Science Inventory

High throughput screening (HTS) data characterizing chemical-induced biological activity has been generated for thousands of environmentally-relevant chemicals by the US inter-agency Tox21 and the US EPA ToxCast programs. For a limited set of chemicals, bioactive concentrations r...

High Throughput Exposure Estimation Using NHANES Data (SOT)

EPA Science Inventory

In the ExpoCast project, high throughput (HT) exposure models enable rapid screening of large numbers of chemicals for exposure potential. Evaluation of these models requires empirical exposure data and due to the paucity of human metabolism/exposure data such evaluations includ...

MASH test 3-11 on the 5-inch cast in place deck barrier anchors.

DOT National Transportation Integrated Search

2011-12-01

A full-scale crash test was performed to evaluate the impact performance of a Texas T223 concrete : beam and post bridge rail anchored to a 5-inch cast-in-place deck (CIPD). The testing followed the MASH : standards for Test Level 3 (TL-3) longitudin...

CAST/EiJ and C57BL/6J Mice Differ in Their Oral and Postoral Attraction to Glucose and Fructose.

PubMed

Sclafani, Anthony; Vural, Austin S; Ackroff, Karen

2017-03-01

A recent study indicated that CAST/EiJ and C57BL/6J mice differ in their taste preferences for maltodextrin but display similar sucrose preferences. The present study revealed strain differences in preferences for the constituent sugars of sucrose. Whereas B6 mice preferred 8% glucose to 8% fructose in 2-day tests, the CAST mice preferred fructose to glucose. These preferences emerged with repeated testing which suggested post-oral influences. In a second experiment, 2-day choice tests were conducted with the sugars versus a sucralose + saccharin (SS) mixture which is highly preferred in brief access tests. B6 mice strongly preferred glucose but not fructose to the non-nutritive SS whereas CAST mice preferred SS to both glucose and fructose even when food restricted. This implied that CAST mice are insensitive to the postoral appetite stimulating actions of the 2 sugars. A third experiment revealed, however, that intragastric glucose and fructose infusions conditioned significant but mild flavor preferences in CAST mice, whereas in B6 mice glucose conditioned a robust preference but fructose was ineffective. Thus, unlike other mouse strains and rats, glucose is not more reinforcing than fructose in CAST mice. Their oral preference for fructose over glucose may be related to a subsensitive maltodextrin receptor or glucose-specific receptor which is stimulated by glucose but not fructose. The failure of CAST mice to prefer glucose to a non-nutritive sweetener distinguishes this strain from other mouse strains and rats. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Effectiveness of Removable Walker Cast Versus Nonremovable Fiberglass Off-Bearing Cast in the Healing of Diabetic Plantar Foot Ulcer

PubMed Central

Faglia, Ezio; Caravaggi, Carlo; Clerici, Giacomo; Sganzaroli, Adriana; Curci, Vincenzo; Vailati, Wanda; Simonetti, Daniele; Sommalvico, Francesco

2010-01-01

OBJECTIVE To evaluate the efficacy of a removable cast walker compared with that of a nonremovable fiberglass off-bearing cast in the treatment of diabetic plantar foot ulcer. RESEARCH DESIGN AND METHODS Forty-five adult diabetic patients with nonischemic, noninfected neuropathic plantar ulcer were randomly assigned for treatment with a nonremovable fiberglass off-bearing cast (total contact cast [TCC] group) or walker cast (Stabil-D group). Treatment duration was 90 days. Percent reduction in ulcer surface area and total healing rates were evaluated after treatment. RESULTS A total of 48 patients were screened; however, 2 patients in the TCC group and 1 patient in the Stabil-D group did not complete the study and were considered dropouts. There were no significant differences in demographic and clinic characteristics of the 45 patients completing the study. Ulcer surface decreased from 1.41 to 0.21 cm2 (P < 0.001) in the TCC group and from 2.18 to 0.45 cm2 (P < 0.001) in the Stabil-D group, with no significant differences between groups (P = 0.722). Seventeen patients (73.9%) in the TCC group and 16 patients (72.7%) in the Stabil-D group achieved healing (P = 0.794). Average healing time was 35.3 ± 3.1 and 39.7 ± 4.2 days in the TCC and Stabil-D group, respectively (P = 0.708). CONCLUSIONS The Stabil-D cast walker, although removable, was equivalent in efficacy to the TCC in terms of ulcer size reduction and total healing rate. The easier use of Stabil-D may help increase the use of off-loading devices in the management of plantar neuropathic diabetic foot ulcers. PMID:20357377

Effect of Porosity on Deformation, Damage, and Fracture of Cast Steel

NASA Astrophysics Data System (ADS)

Hardin, R. A.; Beckermann, C.

2013-12-01

A combined experimental and computational study is performed to investigate the effect of centerline shrinkage porosity on deformation, damage, and fracture of cast steel under tensile testing. Steel plates containing shrinkage porosity are cast in sand molds, machined into test coupons, and tensile tested to fracture. The average volumetric porosity in the gage section of the specimens with porosity ranges from 0.10 to 0.27 pct. Ductility in the test castings with porosity is markedly reduced with the percent elongation data ranging from 12.8 to 19.6 pct; vs 22 pct elongation for the sound material. Radiographic imaging is used to measure and reconstruct the porosity field in the test specimens. The reconstructed porosity field is then used in a finite-element stress analysis simulating the tensile testing. Local elastic properties are reduced according to the porosity fraction present. Porous metal plasticity theory is used to model the damage due to porosity and the fracture. Good agreement is obtained between the measured and predicted stress-strain curves and fracture behaviors. The reduction in ductility is predicted well by comparing the measured and the simulated elongations. The computational modeling approach used in this study allows for a detailed evaluation of the effect of porosity, including its size, shape, and location, on the fracture behavior of steel castings.

Marginal accuracy of nickel chromium copings fabricated by conventional and accelerated casting procedures, produced with ringless and metal ring investment procedures: A comparative in vitro study

PubMed Central

Alex, Deepa; Shetty, Y. Bharath; Miranda, Glynis Anita; Prabhu, M. Bharath; Karkera, Reshma

2015-01-01

Background: Conventional investing and casting techniques are time-consuming and usually requires 2–4 h for completion. Accelerated nonstandard, casting techniques have been reported to achieve similar quality results in significantly less time, namely, in 30–40 min. During casting, it is essential to achieve compensation for the shrinkage of solidifying alloy by investment expansion. The metal casting ring restricts the thermal expansion of investment because the thermal expansion of the ring is lesser than that of the investment. The use of casting ring was challenged with the introduction of the ringless technique. Materials and Methods: A total of 40 test samples of nickel chromium (Ni-Cr) cast copings were obtained from the patterns fabricated using inlay casting wax. The 20 wax patterns were invested using metal ring and 20 wax patterns were invested using the ringless investment system. Of both the groups, 10 samples underwent conventional casting, and the other 10 underwent accelerated casting. The patterns were casted using the induction casting technique. All the test samples of cast copings were evaluated for vertical marginal gaps at four points on the die employing a stereo optical microscope. Results: The vertical marginal discrepancy data obtained were tabulated. Mean and standard deviations were obtained. Vertical discrepancies were analyzed using analysis of variance and Tukey honestly significantly different. The data obtained were found to be very highly significant (P < 0.001). Mean vertical gap was the maximum for Group II (53.64 μm) followed by Group IV (47.62 μm), Group I (44.83 μm) and Group III (35.35 μm). Conclusion: The Ni-Cr cast copings fabricated with the conventional casting using ringless investment system showed significantly better marginal fit than that of cast copings fabricated from conventional and accelerated casting with metal ring investment and accelerated casting using ringless investment since those copings had shown the least vertical marginal discrepancies among the four methods evaluated in this study. PMID:26929488

Development and evaluation of polyvinyl-alcohol blend polymer films as battery separators

NASA Technical Reports Server (NTRS)

Manzo, M. A.

1982-01-01

Several dialdehydes and epoxies were evaluated for their suitability as cross-linkers. Optium concentrations of several cross-linking reagents were determined. A two-step method of cross-linking, which involves treatment of the film in an acid or acid periodate bath, was investigated and dropped in favor of a one-step method in which the acid catalyst, which initiates cross-linking, is added to the PVA - cross-linker solution before casting. The cross-linking was thus achieved during the drying step. This one-step method was much more adaptable to commercial processing. Cross-linked films were characterized as alkaline battery separators. Films were prepared in the lab and tested in cells in order to evaluate the effect of film composition and a number of processing parameters on cell performance. These tests were conducted in order to provide a broader data base from which to select optimum processing parameters. Results of the separator screening tests and the cell tests are discussed.

Repair welding of cast iron coated electrodes

NASA Astrophysics Data System (ADS)

Żuk, M.; Górka, J.; Dojka, R.; Czupryński, A.

2017-08-01

Welding cast iron is a complex production procedure. Repair welding was used to repair damaged or poorly made castings. This is due to a tendency to cracking of the material during welding as well as after it. Welding cast iron can be carried out on hot or on cold. Hot welding requires high heat material and the use of welding material in the form of cast iron. In the case of cold welding, it is possible to use different materials. Mostly used filler metals are nickel and copper based. The work shows the course of research concerning repairmen of ductile iron with arc welding method. For the reparation process four types of ESAB company coated electrodes dedicated for cast iron were used with diameter 3.2 and 4 mm: ES 18-8-6B (4mm), EB 150 (4mm), OK NiCl, EŻM. In the cast iron examined during the testing grooves were made using plasma methods, in order to simulate the removed casting flaws. Then the welding process with coated electrodes was executed. The process utilized low welding current row of 100A, so there would only be a small amount of heat delivered to the heat affected zone (HAZ). Short stitches were made, after welding it was hammered, in order to remove stresses. After the repair welding the part of studies commenced which purpose was finding surface defects using visual testing (VT) and penetration testing (PT). In the second part, a series of macro and microscopic studies were executed witch the purpose of disclosuring the structure. Then the hardness tests for welds cross sections were performed. An important aspect of welding cast iron is the colour of the padding weld after welding, more precisely the difference between the base material and padding weld, the use of different materials extra gives the extra ability to select the best variant. The research of four types of coated electrode was executed, based on the demands the best option in terms of aesthetic, strength and hardness.

Management options for echogenic intracardiac focus and choroid plexus cysts: a review including Australian Association of Obstetrical and Gynaecological Ultrasonologists consensus statement.

PubMed

Bethune, M

2007-08-01

Echogenic intracardiac focus and choroid plexus cysts are common findings at the midtrimester ultrasound. These findings have been linked with an increased risk of Down syndrome and trisomy 18. Most fetuses with these findings will, however, not have chromosomal abnormalities, especially when these findings are isolated. Patients experience considerable anxiety when informed of these findings and require extensive counselling in order to minimize anxiety not only about aneuploidy but also about the structure and development of the heart and brain. Although early studies showed an association with aneuploidies, several recent studies have cast doubt on this association. Many of the early studies were carried out in high-risk populations or in populations that had not had the benefit of other screening tests. Many Australian and New Zealand patients will access screening tests designed to detect these aneuploidies before presenting for a midtrimester ultrasound. Patients who have been screened by nuchal translucency, maternal serum screening or some combination of the two will already have had most cases of Down syndrome and trisomy 18 detected, and any soft marker found will almost certainly be a false positive. It is time to rethink the management of these markers. Recent evidence indicates that if these markers are found in isolation in an otherwise low-risk pregnancy, then there is minimal or no increase in the risk of Down syndrome or trisomy 18: these markers should be considered normal variants. The Australian Association of Obstetrical and Gynaecological Ultrasonologists consensus statement on these markers is included.

Prevalence of the β(S) gene among scheduled castes, scheduled tribes and other backward class groups in Central India.

PubMed

Shrikhande, Anuradha V; Arjunan, Aishwarya; Agarwal, Amit; Dani, Aarti; Tijare, Jayashri; Gettig, Elizabeth; Krishnamurti, Lakshmanan

2014-01-01

Sickle cell disease is an inherited disorder of the blood, and characterized by vasoocclusive crises (VOC), risks for pneumococcal infections and organ toxicities, is associated with morbidity and premature mortality. India, with a population of 1.2 billion individuals, is estimated to be home to over 50.0% of the world's patients with sickle cell disease. The β(S) gene [β6(A3)Glu→Val; HBB: c.20A>T] has the highest prevalence in three socio-economically disadvantaged ethnic categories: the Scheduled Castes (SC), the Scheduled Tribes (ST), and Other Backward Class (OBC) groups in India. The tradition of endogamy practiced by the ethnic groups in India provides the rationale for the screening of individual populations to better understand the distribution of the β(S) gene, guide counseling and awareness programs and aid development of public policy. We undertook a study to describe the prevalence of the β(S) gene in these ethnic groups in the district of Nagpur, Maharashtra in Central India. Through community screening and subsequent targeted screening of high risk individuals, 35,636 individuals were screened, of whom 5466 were found to have sickle cell trait and 1010 were identified with sickle cell disease. Community screening revealed a sickle cell trait prevalence of 13.0% in the SC, 12.0% in the ST and 3.4% in the OBC population. This study describes the prevalence of the β(S) gene within these groups in Central India determined by large scale community screening. This program has uncovered previously undiagnosed cases, provided detailed information to guide population-based disease counseling, prevention and comprehensive care programs.

Quiet breathing in hindlimb casted mice.

PubMed

Receno, Candace N; Roffo, Katelynn E; Mickey, Marisa C; DeRuisseau, Keith C; DeRuisseau, Lara R

2018-06-07

The hindlimb casting model was developed to study skeletal muscle reloading following a period of unloading. It is unknown if ventilation parameters of mice are affected by the casting model. We tested the hypothesis that hindlimb casted mice have similar ventilatory patterns compared to mice with the casts removed. Male CD-1 mice underwent 14 days of hindlimb immobilization via plaster casting. Breathing parameters were obtained utilizing unrestrained barometric plethysmography (UBP). Breathing traces were analyzed with Ponemah software for breathing frequency, tidal volume (TV), and minute ventilation (MV). Frequency, TV and MV did not show any differences in quiet breathing patterns during or post-casting in mice. Thus, the hindlimb casting model does not complicate breathing during and after casting and should not interfere with the unloading and reloading of skeletal muscle. Copyright © 2018 Elsevier B.V. All rights reserved.

Developing Methods Using ToxCast Data for the Classification and Prioritization of Antimicrobials and Inerts

EPA Science Inventory

Improved chemical risk management and increased efficiency of chemical prioritization, classification and assessment are major goals within EPA. Towards achieving these goals, EPA's ToxCast™ research program has been designed to rapidly screen hundreds to thousands of chemicals' ...

Multiscale Systems Modeling of Male Reproductive Tract Defects: from Genes to Populations (SOT)

EPA Science Inventory

The reproductive tract is a complex, integrated organ system with diverse embryology and unique sensitivity to prenatal environmental exposures that disrupt morphoregulatory processes and endocrine signaling. U.S. EPA’s in vitro high-throughput screening (HTS) database (ToxCastDB...

Screening the ToxCast Phase 1 chemical library for inhibition of deiodinase type 1 activity

EPA Science Inventory

Thyroid hormone (TH) homeostasis is dependent upon coordination of multiple key events including iodide uptake, hormone synthesis, metabolism and elimination, to maintain proper TH signaling. Deiodinase enzymes catalyze iodide release from THs to interconvert THs between active a...

Screening the ToxCast Phase I Chemical Library for inhibition of Deiodinase Type I enzyme activity

EPA Science Inventory

Thyroid hormone (TH) signaling in vertebrates is dependent upon coordination of multiple key events including iodide uptake, hormone synthesis, metabolism and elimination, to maintain proper homeostasis of the hormones. Deiodinase enzymes interconvert THs between less active and...

Applying 21st century tools to watersheds of the western US: Sites, bioactivities, and chemicals of concern

EPA Science Inventory

The webinar focused on ways that ToxCast high throughput screening data and the adverse outcome pathway framework, under development in the CSS program, can be used to prioritize environmental contaminants for monitoring and management.

Activity profiles of 676 ToxCast Phase II compounds in 231 biochemical high-throughput screening assays

EPA Science Inventory

Understanding potential health risks posed by environmental chemicals is a significant challenge elevated by large numbers of diverse chemicals with generally uncharacterized exposures, mechanisms and toxicities. The present study is a performance evaluation and critical analysis...

Analysis and comparison of the biomechanical properties of univalved and bivalved cast models.

PubMed

Crickard, Colin V; Riccio, Anthony I; Carney, Joseph R; Anderson, Terrence D

2011-01-01

Fiberglass casts are frequently valved to relieve the pressure associated with upper extremity swelling after a surgical procedure or when applied after reduction of a displaced fracture in a child. Although different opinions exist regarding the valving of casts, no research to date has explored the biomechanical effects of this commonly used technique. As cast integrity is essential for the maintenance of fracture reduction, it is important to understand whether casts are structurally compromised after valving. Understanding the effects of valving on cast integrity may help guide clinicians in the technique of valving while minimizing the potential for a loss of fracture reduction. Thirty standardized cylindrical fiberglass cast models were created. Ten models were left intact, 10 were univalved, and 10 were bivalved. All the models were mechanically tested by a 3-point bending apparatus secured to a biaxial materials testing system. Load to failure and bending stiffness were recorded for each sample. Differences in load of failure and bending stiffness were compared among the groups. Unvalved cast models had the highest failure load and bending stiffness, whereas bivalved casts showed the lowest value for both failure load and bending stiffness. Univalved casts had a failure load measured to be between those of unvalved and bivalved cast models. Analysis of variance showed significance when failure load and bending stiffness data among all the groups were compared. A post hoc Bonferroni statistical analysis showed significance in bending stiffness between intact and bivalved models (P < 0.01), intact and univalved models (P < 0.01), but no significant difference in bending stiffness between univalved and bivalved models (P > 0.01). Differences in measured failure load values were found to be statistically significant among all cast models (P < 0.01). Valving significantly decreases the bending stiffness and load to failure of fiberglass casts. Univalved casts have a higher load to failure than bivalved casts. Valving adversely alters the structural integrity of fiberglass casts. This may impair a cast's ability to effectively immobilize an extremity or maintain a fracture reduction.

Accuracy of fit of implant-supported bars fabricated on definitive casts made by different dental stones

PubMed Central

Kioleoglou, Ioannis; Pissiotis, Argirios

2018-01-01

Background The purpose of this study was to evaluate the accuracy of fitting of an implant supported screw-retained bar made on definitive casts produced by 4 different dental stone products. Material and Methods The dental stones tested were QuickRock (Protechno), FujiRock (GC), Jade Stone (Whip Mix) and Moldasynt (Heraeus). Three external hexagon implants were placed in a polyoxymethylene block. Definitive impressions were made using monophase high viscosity polyvinylsiloxane in combination with custom trays. Then, definitive models from the different types of dental stones were fabricated. Three castable cylinders with a machined non-enganging base were cast and connected with a very small quantity of PMMA to a cast bar, which was used to verify the marginal discrepancies between the abutments and the prosthetic platforms of the implants. For that purpose special software and a camera mounted on an optical microscope were used. The gap was measured by taking 10 measurements on each abutment, after the Sheffield test was applied. Twelve definitive casts were fabricated for each gypsum product and 40 measurements were performed for each cast. Mean, minimum, and maximum values were calculated. The Shapiro-Wilk test of normality was performed. Mann-Whitney test (P<.06) was used for the statistical analysis of the measurements. Results The non-parametric Kruskal-Wallis test revealed a statistically significant effect of the stone factor on the marginal discrepancy for all Sheffield test combinations: 1. Abutment 2 when screw was fastened on abutment 1 (χ2=3, df=35.33, P<0.01), 2. Abutment 3 when the screw was fastened on abutment 1 (χ2=3, df=37.74, P<0.01), 3. Abutment 1 when the screw was fastened on abutment 3 (χ2=3, df=39.79, P<0.01), 4. Abutment 2 when the screw was fastened on abutment 3 (χ2=3, df=37.26, P<0.01). Conclusions A significant correlation exists between marginal discrepancy and different dental gypsum products used for the fabrication of definitive casts for implant supported bars. The smallest marginal discrepancy was noted on implant supported bars fabricated on definitive casts made by Type III mounting stone. The biggest marginal discrepancy was noted on implant supported bars fabricated on definitive casts made by Type V dental stone. The marginal discrepancies presented on implant supported bars fabricated on definitive casts made by two types of Type IV dental stone were not significantly different. Key words:Dental implant, passive fit, dental stones, marginal discrepancy. PMID:29721227

Evaluation of left ventricular assist device pump bladders cast from ion-sputtered polytetrafluorethylene mandrels

NASA Technical Reports Server (NTRS)

1982-01-01

A highly thromboresistant blood contacting interface for use in implanatable blood pump is investigated. Biomaterials mechanics, dynamics, durability, surface morphology, and chemistry are among the critical consideration pertinent to the choice of an appropriate blood pump bladder material. The use of transfer cast biopolymers from ion beam textured surfaces is investigated to detect subtle variations in blood pump surface morphology using Biomer as the biomaterial of choice. The efficacy of ion beam sputtering as an acceptable method of fabricating textured blood interfaces is evaluated. Aortic grafts and left ventricular assist devices were implanted in claves; the blood interfaces were fabricated by transfer casting methods from ion beam textured polytetrafluorethylene mandrels. The mandrels were textured by superimposing a 15 micron screen mesh; ion sputtering conditions were 300 volts beam energy, 40 to 50 mA beam, and a mandrel to source distance of 25 microns.

Analysis of four dental alloys following torch/centrifugal and induction/ vacuum-pressure casting procedures.

PubMed

Thompson, Geoffrey A; Luo, Qing; Hefti, Arthur

2013-12-01

Previous studies have shown casting methodology to influence the as-cast properties of dental casting alloys. It is important to consider clinically important mechanical properties so that the influence of casting can be clarified. The purpose of this study was to evaluate how torch/centrifugal and inductively cast and vacuum-pressure casting machines may affect the castability, microhardness, chemical composition, and microstructure of 2 high noble, 1 noble, and 1 base metal dental casting alloys. Two commonly used methods for casting were selected for comparison: torch/centrifugal casting and inductively heated/ vacuum-pressure casting. One hundred and twenty castability patterns were fabricated and divided into 8 groups. Four groups were torch/centrifugally cast in Olympia (O), Jelenko O (JO), Genesis II (G), and Liberty (L) alloys. Similarly, 4 groups were cast in O, JO, G, and L by an inductively induction/vacuum-pressure casting machine. Each specimen was evaluated for casting completeness to determine a castability value, while porosity was determined by standard x-ray techniques. Each group was metallographically prepared for further evaluation that included chemical composition, Vickers microhardness, and grain analysis of microstructure. Two-way ANOVA was used to determine significant differences among the main effects. Statistically significant effects were examined further with the Tukey HSD procedure for multiple comparisons. Data obtained from the castability experiments were non-normal and the variances were unequal. They were analyzed statistically with the Kruskal-Wallis rank sum test. Significant results were further investigated statistically with the Steel-Dwass method for multiple comparisons (α=.05). The alloy type had a significant effect on surface microhardness (P<.001). In contrast, the technique used for casting did not affect the microhardness of the test specimen (P=.465). Similarly, the interaction between the alloy and casting technique was not significant (P=.119). A high level of castability (98.5% on average) was achieved overall. The frequency of casting failures as a function of alloy type and casting method was determined. Failure was defined as a castability index score of <100%. Three of 28 possible comparisons between alloy and casting combinations were statistically significant. The results suggested that casting technique affects the castability index of alloys. Radiographic analysis detected large porosities in regions near the edge of the castability pattern and infrequently adjacent to noncast segments. All castings acquired traces of elements found in the casting crucibles. The grain size for each dental casting alloy was generally finer for specimens produced by the induction/vacuum-pressure method. The difference was substantial for JO and L. This study demonstrated a relation between casting techniques and some physical properties of metal ceramic casting alloys. Copyright © 2013 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Bond strengths of custom cast and prefabricated posts luted with two cements.

PubMed

Aleisa, Khalil Ibrahim

2011-02-01

This in vitro study evaluated the bond strength of custom cast and prefabricated posts luted with resin or zinc phosphate cements into unobturated canals of extracted teeth. Forty-eight custom cast and prefabricated posts were placed into extracted single-rooted human teeth. Post-cavity preparation was 1.5 mm in diameter and 10 mm in depth. Specimens were randomly divided into 4 groups of 12 each. Two of the groups were then luted with resin cement, while the other two groups were luted with zinc phosphate cement. A pull-out bond strength evaluation was performed using a universal testing machine. The Kolmogorov-Smirnov test was used to prove normal distribution. Data were statistically analyzed using two-way ANOVA and the Student t test (alpha = .05). For both luting agents, the prefabricated posts group exhibited significantly less bond strength than the custom cast posts group (P = .0001). There were statistically significant differences in mean bond strength for the prefabricated posts group luted with resin cement vs the group cemented with zinc phosphate cement (P = .002). There was no significant difference between the mean bond strength values of custom cast posts luted with resin cement or zinc phosphate cement. Custom cast posts showed significantly greater bond strength than prefabricated posts when luted with either resin or zinc phosphate cements. The type of cement had less significance on the retention of custom cast posts.

Comparative Evaluation of Conventional and Accelerated Castings on Marginal Fit and Surface Roughness

PubMed Central

Jadhav, Vivek Dattatray; Motwani, Bhagwan K.; Shinde, Jitendra; Adhapure, Prasad

2017-01-01

Aims: The aim of this study was to evaluate the marginal fit and surface roughness of complete cast crowns made by a conventional and an accelerated casting technique. Settings and Design: This study was divided into three parts. In Part I, the marginal fit of full metal crowns made by both casting techniques in the vertical direction was checked, in Part II, the fit of sectional metal crowns in the horizontal direction made by both casting techniques was checked, and in Part III, the surface roughness of disc-shaped metal plate specimens made by both casting techniques was checked. Materials and Methods: A conventional technique was compared with an accelerated technique. In Part I of the study, the marginal fit of the full metal crowns as well as in Part II, the horizontal fit of sectional metal crowns made by both casting techniques was determined, and in Part III, the surface roughness of castings made with the same techniques was compared. Statistical Analysis Used: The results of the t-test and independent sample test do not indicate statistically significant differences in the marginal discrepancy detected between the two casting techniques. Results: For the marginal discrepancy and surface roughness, crowns fabricated with the accelerated technique were significantly different from those fabricated with the conventional technique. Conclusions: Accelerated casting technique showed quite satisfactory results, but the conventional technique was superior in terms of marginal fit and surface roughness. PMID:29042726

Durability of Membrane Electrode Assemblies (MEAs) in PEM Fuel Cells Operated on Pure Hydrogen and Oxygen

NASA Technical Reports Server (NTRS)

Stanic, Vesna; Braun, James; Hoberecht, Mark

2003-01-01

Proton exchange membrane (PEM) fuel cells are energy sources that have the potential to replace alkaline fuel cells for space programs. Broad power ranges, high peak-to-nominal power capabilities, low maintenance costs, and the promise of increased life are the major advantages of PEM technology in comparison to alkaline technology. The probability of PEM fuel cells replacing alkaline fuel cells for space applications will increase if the promise of increased life is verified by achieving a minimum of 10,000 hours of operating life. Durability plays an important role in the process of evaluation and selection of MEAs for Teledyne s Phase I contract with the NASA Glenn Research Center entitled Proton Exchange Membrane Fuel cell (PEMFC) Power Plant Technology Development for 2nd Generation Reusable Launch Vehicles (RLVs). For this contract, MEAs that are typically used for H2/air operation were selected as potential candidates for H2/O2 PEM fuel cells because their catalysts have properties suitable for O2 operation. They were purchased from several well-established MEA manufacturers who are world leaders in the manufacturing of diverse products and have committed extensive resources in an attempt to develop and fully commercialize MEA technology. A total of twelve MEAs used in H2/air operation were initially identified from these manufacturers. Based on the manufacturers specifications, nine of these were selected for evaluation. Since 10,000 hours is almost equivalent to 14 months, it was not possible to perform continuous testing with each MEA selected during Phase I of the contract. Because of the lack of time, a screening test on each MEA was performed for 400 hours under accelerated test conditions. The major criterion for an MEA pass or fail of the screening test was the gas crossover rate. If the gas crossover rate was higher than the membrane intrinsic permeability after 400 hours of testing, it was considered that the MEA had failed the test. Three types of MEAs out of the nine total membranes failed the test. The evaluation results showed that fuel cell operating conditions (current, pressure, stoichiometric flow rates) were the parameters that influenced the durability of MEAs. In addition, the durability test results indicated that the type of membrane was also an important parameter for MEA durability. At accelerated test conditions, the MEAs with casted membranes failed during the 400 hour test. However, the MEAs prepared from the casted membrane with support as well as extruded membranes, both passed the 400h durability test at accelerated operating test conditions. As a result of the MEA accelerated durability tests, four MEAs were selected for further endurance testing. These tests are being carried out with four-cell stacks under nominal fuel cell operating conditions.

ToxCast: Developing Predictive Signatures of Chemically Induced Toxicity (Developing Predictive Bioactivity Signatures from ToxCasts HTS Data)

EPA Science Inventory

ToxCast, the United States Environmental Protection Agency’s chemical prioritization research program, is developing methods for utilizing computational chemistry, bioactivity profiling and toxicogenomic data to predict potential for toxicity and prioritize limited testing resour...

Accuracy of impressions with different impression materials in angulated implants.

PubMed

Reddy, S; Prasad, K; Vakil, H; Jain, A; Chowdhary, R

2013-01-01

To evaluate the dimensional accuracy of the resultant (duplicative) casts made from two different impression materials (polyvinyl siloxane and polyether) in parallel and angulated implants. Three definitive master casts (control groups) were fabricated in dental stone with three implants, placed at equi-distance. In first group (control), all three implants were placed parallel to each other and perpendicular to the plane of the cast. In the second and third group (control), all three implants were placed at 10° and 15 o angulation respectively to the long axis of the cast, tilting towards the centre. Impressions were made with polyvinyl siloxane and polyether impression materials in a special tray, using a open tray impression technique from the master casts. These impressions were poured to obtain test casts. Three reference distances were evaluated on each test cast by using a profile projector and compared with control groups to determine the effect of combined interaction of implant angulation and impression materials on the accuracy of implant resultant cast. Statistical analysis revealed no significant difference in dimensional accuracy of the resultant casts made from two different impression materials (polyvinyl siloxane and polyether) by closed tray impression technique in parallel and angulated implants. On the basis of the results of this study, the use of both the impression materials i.e., polyether and polyvinyl siloxane impression is recommended for impression making in parallel as well as angulated implants.

A Redox Sensitive Pathway in the Mouse ES Cell Assay Modeled From ToxCast HTS Data

EPA Science Inventory

The broad chemical landscape coupled with the lack of developmental toxicity information across most environmental chemicals has motivated the need for high- throughput screening methods and predictive models of developmental toxicity. Towards this end, we used the mouse embryoni...

High-Throughput Simulation of Environmental Chemical Fate for Exposure Prioritization

EPA Science Inventory

The U.S. EPA must consider lists of hundreds to thousands of chemicals when allocating resources to identify risk in human populations and the environment. High-throughput screening assays to characterize biological activity in vitro have allowed the ToxCastTM program to identify...

46 CFR 160.032-5 - Inspection and testing of davits.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Inspection and testing of davits. (a) Material testing. (1) Where davit arms and frames are fabricated of steel castings, an inspector shall be present at the foundry where such castings are made to witness the... affidavit stating that the structural steel complies with the requirements of the specification noted in...

46 CFR 160.032-5 - Inspection and testing of davits.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Inspection and testing of davits. (a) Material testing. (1) Where davit arms and frames are fabricated of steel castings, an inspector shall be present at the foundry where such castings are made to witness the... affidavit stating that the structural steel complies with the requirements of the specification noted in...

Secondary Waste Simulant Development for Cast Stone Formulation Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Renee L.; Westsik, Joseph H.; Rinehart, Donald E.

Washington River Protection Solutions, LLC (WRPS) funded Pacific Northwest National Laboratory (PNNL) to conduct a waste form testing program to implement aspects of the Secondary Liquid Waste Treatment Cast Stone Technology Development Plan (Ashley 2012) and the Hanford Site Secondary Waste Roadmap (PNNL 2009) related to the development and qualification of Cast Stone as a potential waste form for the solidification of aqueous wastes from the Hanford Site after the aqueous wastes are treated at the Effluent Treatment Facility (ETF). The current baseline is that the resultant Cast Stone (or grout) solid waste forms would be disposed at the Integratedmore » Disposal Facility (IDF). Data and results of this testing program will be used in the upcoming performance assessment of the IDF and in the design and operation of a solidification treatment unit planned to be added to the ETF. The purpose of the work described in this report is to 1) develop simulants for the waste streams that are currently being fed and future WTP secondary waste streams also to be fed into the ETF and 2) prepare simulants to use for preparation of grout or Cast Stone solid waste forms for testing.« less

Characterization of Technetium Speciation in Cast Stone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Um, Wooyong; Jung, Hun Bok; Wang, Guohui

2013-11-11

This report describes the results from laboratory tests performed at Pacific Northwest National Laboratory (PNNL) for the U.S. Department of Energy (DOE) EM-31 Support Program (EMSP) subtask, “Production and Long-Term Performance of Low Temperature Waste Forms” to provide additional information on technetium (Tc) speciation characterization in the Cast Stone waste form. To support the use of Cast Stone as an alternative to vitrification for solidifying low-activity waste (LAW) and as the current baseline waste form for secondary waste streams at the Hanford Site, additional understanding of Tc speciation in Cast Stone is needed to predict the long-term Tc leachability frommore » Cast Stone and to meet the regulatory disposal-facility performance requirements for the Integrated Disposal Facility (IDF). Characterizations of the Tc speciation within the Cast Stone after leaching under various conditions provide insights into how the Tc is retained and released. The data generated by the laboratory tests described in this report provide both empirical and more scientific information to increase our understanding of Tc speciation in Cast Stone and its release mechanism under relevant leaching processes for the purpose of filling data gaps and to support the long-term risk and performance assessments of Cast Stone in the IDF at the Hanford Site.« less

CAST-10-2/DOA 2 Airfoil Studies Workshop Results

NASA Technical Reports Server (NTRS)

Ray, Edward J. (Compiler); Hill, Acquilla S. (Compiler)

1989-01-01

During the period of September 23 through 27, 1988, the Transonic Aerodynamics Division at the Langely Research Center hosted an International Workshop on CAST-10-2/DOA 2 Airfoil Studies. The CAST-10 studies were the outgrowth of several cooperative study agreements among the NASA, the NAE of Canada, the DLR of West Germany, and the ONERA of France. Both theoretical and experimental CAST-10 airfoil results that were obtained form an extensive series of tests and studies, were reviewed. These results provided an opportunity to make direct comparisons of adaptive wall test section (AWTS) results from the NASA 0.3-meter Transonic Cryogenic Tunnel and ONERA T-2 AWTS facilities with conventional ventilated wall wind tunnel results from the Canadian high Reynolds number two-dimensional test facility. Individual papers presented during the workshop are included.

Considerations in Use of the EPA’s ToxCast Data for Environmental Toxicology (SETAC)

EPA Science Inventory

The US EPA has developed the ToxCast program to prioritize chemicals for selective toxicity testing. ToxCast relies on extensive bioactivity profiling using a panel of biochemical and cellular assays that measure chemicals effects on potential molecular initiating events and key ...

Effect of molybdenum, vanadium, boron on mechanical properties of high chromium white cast iron in as-cast condition

NASA Astrophysics Data System (ADS)

Nurjaman, F.; Sumardi, S.; Shofi, A.; Aryati, M.; Suharno, B.

2016-02-01

In this experiment, the effect of the addition carbide forming elements on high chromium white cast iron, such as molybdenum, vanadium and boron on its mechanical properties and microstructure was investigated. The high chromium white cast iron was produced by casting process and formed in 50 mm size of grinding balls with several compositions. Characterization of these grinding balls was conducted by using some testing methods, such as: chemical and microstructure analysis, hardness, and impact test. From the results, the addition of molybdenum, vanadium, and boron on high chromium white cast iron provided a significant improvement on its hardness, but reduced its toughness. Molybdenum induced fully austenitic matrix and Mo2C formation among eutectic M7C3 carbide. Vanadium was dissolved in the matrix and carbide. While boron was played a role to form fine eutectic carbide. Grinding balls with 1.89 C-13.1 Cr-1.32 Mo-1.36 V-0.00051 B in as-cast condition had the highest hardness, which was caused by finer structure of eutectic carbide, needle like structure (upper bainite) matrix, and martensite on its carbide boundary.

Cobalt Phthalocyanine Modified Electrodes Utilised in Electroanalysis: Nano-Structured Modified Electrodes vs. Bulk Modified Screen-Printed Electrodes

PubMed Central

Foster, Christopher W.; Pillay, Jeseelan; Metters, Jonathan P.; Banks, Craig E.

2014-01-01

Cobalt phthalocyanine (CoPC) compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated within the ink of a screen-printed sensor, providing a one-shot economical and disposable electrode configuration. In this paper we critically compare CoPC modified electrodes prepared by drop casting CoPC nanoparticles (nano-CoPC) onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes in the sensing of the model analytes l-ascorbic acid, oxygen and hydrazine. It is found that no “electrocatalysis” is observed towards l-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where “electrocatalysis” has been reported with no clear control experiments undertaken. On the other hand true electrocatalysis is observed towards hydrazine, where no such voltammetric features are witnessed on the bare underlying electrode substrate. PMID:25414969

Recent Developments in Toxico-Cheminformatics; Supporting ...

EPA Pesticide Factsheets

EPA's National Center for Computational Toxicology is building capabilities to support a new paradigm for toxicity screening and prediction through the harnessing of legacy toxicity data, creation of data linkages, and generation of new high-content and high-thoughput screening data. In association with EPA's ToxCast, ToxRefDB, and ACToR projects, the DSSTox project provides cheminformatics support and, in addition, is improving public access to quality structure-annotated chemical toxicity information in less summarized forms than traditionally employed in SAR modeling, and in ways that facilitate data-mining and data read-across. The latest DSSTox version of the Carcinogenic Potency Database file (CPDBAS) illustrates ways in which various summary definitions of carcinogenic activity can be employed in modeling and data mining. DSSTox Structure-Browser provides structure searchability across all published DSSTox toxicity-related inventory, and is enabling linkages between previously isolated toxicity data resources associated with environmental and industrial chemicals. The public DSSTox inventory also has been integrated into PubChem, allowing a user to take full advantage of PubChem structure-activity and bioassay clustering features. Phase I of the ToxCast project is generating high-throughput screening data from several hundred biochemical and cell-based assays for a set of 320 chemicals, mostly pesticide actives with rich toxicology profiles. Incorporating

High-efficiency screen-printed belt co-fired solar cells on cast multicrystalline silicon

NASA Astrophysics Data System (ADS)

Upadhyaya, Ajay; Sheoran, Manav; Rohatgi, Ajeet

2005-01-01

High-efficiency 4cm2 untextured screen-printed solar cells were achieved on cast multicrystalline silicon. These cells were fabricated using a simple manufacturable process involving POCl3 diffusion for emitter, PECVD SiNx:H deposition for a single-layer antireflection coating and rapid co-firing of Ag grid, Al backcontact, and Al-BSF in a belt furnace. An optimized process sequence contributed to effective impurity gettering and defect passivation, resulting in high average bulk lifetimes in the range of 100-250 μs after the cell processing. The contact firing contributed to good ohmic contacts with low series resistance of <1Ωcm2, low backsurface recombination velocity of <500cm/s, and high fill factors of ˜0.78. These parameters resulted in 16.9% and 16.8% efficient untextured screen-printed cells with a single layer AR coating on heat exchanger method (HEM) and Baysix mc-Si. The identical process applied to the untextured float zone wafers gave an efficiency of 17.2%. The same optimized co-firing cycle, when applied to HEM mc-Si wafers with starting lifetimes varying over a wide range of 4-70 μs, resulted in cell efficiencies in the range of 16.5%-17%.

Effect of pressure difference on the quality of titanium casting.

PubMed

Watanabe, I; Watkins, J H; Nakajima, H; Atsuta, M; Okabe, T

1997-03-01

In casting titanium using a two-compartment casting machine, Herø et al. (1993) reported that the pressure difference between the melting chamber and the mold chamber affected the soundness of the castings. This study tested the hypothesis that differences in pressure produce castings with various amounts of porosity and different mechanical properties values. Plastic dumbbell-shaped patterns were invested with an alumina-based, phosphate-bonded investment material. Both chambers of the casting machine were evacuated to 6 x 10(-2) torr; the argon pressure difference was then adjusted to either 50, 150, 300, or 450 torr. The porosity of the cast specimens was determined by x-ray radiography and quantitative image analysis. Tensile strength and elongation were measured by means of a universal testing machine at a strain rate of 1.7 x 10(-4)/s. The fractured surfaces were examined by SEM. Changes in Vickers hardness with depth from the cast surface were measured on polished cross-sections of the specimens. Raising the argon pressure difference to 300 and 450 torr caused a significant increase in internal porosity and a resultant decrease in the engineering tensile strength and elongation. The highest tensile strength (approximately 540 MPa), elongation (approximately 10%), bulk hardness (HV50g 209), and lowest porosity level (approximately 0.8%) occurred in the specimens cast at 150 torr. Turbulence of the metal during casting was thought to be responsible for the increase in porosity levels with the increase in argon pressure difference. By choosing an argon pressure difference (around 150 torr) suitable for this geometry, we could produce castings which have adequate mechanical properties and low porosity levels.

Additive Manufacturing and Casting Technology Comparison: Mechanical Properties, Productivity and Cost Benchmark

NASA Astrophysics Data System (ADS)

Vevers, A.; Kromanis, A.; Gerins, E.; Ozolins, J.

2018-04-01

The casting technology is one of the oldest production technologies in the world but in the recent years metal additive manufacturing also known as metal 3D printing has been evolving with huge steps. Both technologies have capabilities to produce parts with internal holes and at first glance surface roughness is similar for both technologies, which means that for precise dimensions parts have to be machined in places where precise fit is necessary. Benchmark tests have been made to find out if parts which are produced with metal additive manufacturing can be used to replace parts which are produced with casting technology. Most of the comparative tests have been made with GJS-400-15 grade which is one of the most popular cast iron grades. To compare mechanical properties samples have been produced using additive manufacturing and tested for tensile strength, hardness, surface roughness and microstructure and then the results have been compared with the samples produced with casting technology. In addition, both technologies have been compared in terms of the production time and production costs to see if additive manufacturing is competitive with the casting technology. The original paper has been written in the Latvian language as part of the Master Thesis within the framework of the production technology study programme at Riga Technical University.

Modal Vibration Analysis of Large Castings

NASA Technical Reports Server (NTRS)

Werlink, Rudolph J.; Margasahayam, Ravi N.

2009-01-01

The art of experimental modal vibration analysis (MVA) has been extended to apply to large castings. This extension was made to enable the use of experimental MVA as a relatively inexpensive, simple means of assessing the internal structural integrity of tread shoes of crawler transporters used to move spacecraft to the launch pad at Kennedy Space Center. Each tread shoe is made from cast iron and weighs about a ton (has a mass .907 kg). The present extended version of experimental MVA could also be applied to other large castings. It could be especially useful to manufacturers as a means of rapidly discriminating against large castings that contain unacceptably large concentrations of internal defects. The use of experimental MVA to assess structural integrity is not new. What are new here are those aspects of the extension of experimental MVA that pertain to the application of MVA to objects so massive that it may not be practical or cost effective to mount them in special test fixtures that impose special test boundary conditions to test them in place under normal conditions of use.

EPA Exposure Research and the ExpoCast Project: New Methods and New Data (NIEHS Exposome webinar)

EPA Science Inventory

Estimates of human and ecological exposures are required as critical input to risk-based prioritization and screening of thousands of chemicals. In a 2009 commentary in Environmental Health Perspectives, Shelden and Hubal proposed that “Novel statistical and informatic approaches...

EPA Project Updates: DSSTox and ToxCast Generating New Data and Data Linkages for Use in Predictive Modeling

EPA Science Inventory

EPAs National Center for Computational Toxicology is building capabilities to support a new paradigm for toxicity screening and prediction. The DSSTox project is improving public access to quality structure-annotated chemical toxicity information in less summarized forms than tr...

High-Throughput Simulation of Environmental Chemical Fate for Exposure Prioritization (Annual Meeting of ISES)

EPA Science Inventory

The U.S. EPA must consider thousands of chemicals when allocating resources to assess risk in human populations and the environment. High-throughput screening assays to characterize biological activity in vitro are being implemented in the ToxCastTM program to rapidly characteri...

Predictive models of prenatal developmental toxicity from ToxCast high-throughput screening data

EPA Science Inventory

EPA's ToxCast™ project is profiling the in vitro bioactivity of chemicals to assess pathway-level and cell-based signatures that correlate with observed in vivo toxicity. We hypothesized that developmental toxicity in guideline animal studies captured in the ToxRefDB database wou...

Real-Time Growth Kinetics Measuring Hormone Mimicry for ToxCast Chemicals in T‑47D Human Ductal Carcinoma Cells

EPA Science Inventory

High-throughput screening (HTS) assays capable of profiling thousands of environmentally relevant chemicals for in vitro biological activity provide useful information on the potential for disrupting endocrine pathways. Disruption of the estrogen signaling pathway has been implic...

Predictive Toxicology and Computer Simulation of Male Reproductive Development (Duke U KURe and PMRC research day)

EPA Science Inventory

The reproductive tract is a complex, integrated organ system with diverse embryology and unique sensitivity to prenatal environmental exposures that disrupt morphoregulatory processes and endocrine signaling. U.S. EPA’s in vitro high-throughput screening (HTS) database (ToxCastDB...

High Throughput Assays for Exposure Science (NIEHS OHAT Staff Meeting presentation)

EPA Science Inventory

High throughput screening (HTS) data that characterize chemically induced biological activity have been generated for thousands of chemicals by the US interagency Tox21 and the US EPA ToxCast programs. In many cases there are no data available for comparing bioactivity from HTS w...

Leveraging Publically Available Chemical Functional Use Data in Support of Exposure Prediction

EPA Science Inventory

The U.S. EPA Exposure Forecasting (ExpoCast) project aims to provide rapid screening-level exposure predictions for thousands of chemicals, most of which lack detailed exposure data. Chemical functional use - the role a chemical plays in processes or products (e.g. solvent, ant...

Differentiating pathway-specific from nonspecific effects in high-throughput toxicity data: A foundation for prioritizing adverse outcome pathway development

EPA Science Inventory

The U.S. Environmental Protection Agency’s ToxCast program has screened thousands of chemicals for biological activity, primarily using high-throughput in vitro bioassays. Adverse outcome pathways (AOPs) offer a means to link pathway-specific biological activities with potential ...

Using ToxCast data to reconstruct dynamic cell state trajectories and estimate toxicological points of departure

EPA Science Inventory

AbstractBackground. High-throughput in vitro screening is an important tool for evaluating the potential biological activity of the thousands of existing chemicals in commerce and the hundreds more introduced each year. Among the assay technologies available, high-content imaging...

Prioritizing Environmental Chemicals for Obesity and Diabetes Outcomes Research: A Screening Approach Using ToxCast High Throughput Data

EPA Science Inventory

Background: Diabetes and obesity are major threats to public health in the US and abroad. Understanding the role chemicals in our environment play in the development of these conditions is an emerging issue in environmental health, although identifying and prioritizing chemicals ...

EPA DSSTox and ToxCast Project Updates: Generating New Data and Linkages in Support of Public Toxico-Cheminformatics Efforts

EPA Science Inventory

EPA’s National Center for Computational Toxicology is generating data and capabilities to support a new paradigm for toxicity screening and prediction. The DSSTox project is improving public access to quality structure-annotated chemical toxicity information in less summarized fo...

Framework for a Quantitative Systemic Toxicity Model (FutureToxII)

EPA Science Inventory

EPA’s ToxCast program profiles the bioactivity of chemicals in a diverse set of ~700 high throughput screening (HTS) assays. In collaboration with L’Oreal, a quantitative model of systemic toxicity was developed using no effect levels (NEL) from ToxRefDB for 633 chemicals with HT...

A Statistics-Based Cracking Criterion of Resin-Bonded Silica Sand for Casting Process Simulation

NASA Astrophysics Data System (ADS)

Wang, Huimin; Lu, Yan; Ripplinger, Keith; Detwiler, Duane; Luo, Alan A.

2017-02-01

Cracking of sand molds/cores can result in many casting defects such as veining. A robust cracking criterion is needed in casting process simulation for predicting/controlling such defects. A cracking probability map, relating to fracture stress and effective volume, was proposed for resin-bonded silica sand based on Weibull statistics. Three-point bending test results of sand samples were used to generate the cracking map and set up a safety line for cracking criterion. Tensile test results confirmed the accuracy of the safety line for cracking prediction. A laboratory casting experiment was designed and carried out to predict cracking of a cup mold during aluminum casting. The stress-strain behavior and the effective volume of the cup molds were calculated using a finite element analysis code ProCAST®. Furthermore, an energy dispersive spectroscopy fractographic examination of the sand samples confirmed the binder cracking in resin-bonded silica sand.

Early genetic testing of coastal Douglas-fir for Swiss needle cast tolerance.

Treesearch

Fatih Temel; G.R. Johnson; W.T. Adams

2005-01-01

The possibility of early testing coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) for Swiss needle cast (SNC; caused by Phaeocryptopus gaeumannii (Rohde) Petrak) tolerance was investigated using 55 Douglas-fir families from western Oregon. Seedlings were inoculated with P...

High-Content Screening in Zebrafish Embryos Identifies Butafenacil as a Potent Inducer of Anemia

PubMed Central

Leet, Jessica K.; Lindberg, Casey D.; Bassett, Luke A.; Isales, Gregory M.; Yozzo, Krystle L.; Raftery, Tara D.; Volz, David C.

2014-01-01

Using transgenic zebrafish (fli1:egfp) that stably express enhanced green fluorescent protein (eGFP) within vascular endothelial cells, we recently developed and optimized a 384-well high-content screening (HCS) assay that enables us to screen and identify chemicals affecting cardiovascular development and function at non-teratogenic concentrations. Within this assay, automated image acquisition procedures and custom image analysis protocols are used to quantify body length, heart rate, circulation, pericardial area, and intersegmental vessel area within individual live embryos exposed from 5 to 72 hours post-fertilization. After ranking developmental toxicity data generated from the U.S. Environmental Protection Agency's (EPA's) zebrafish teratogenesis assay, we screened 26 of the most acutely toxic chemicals within EPA's ToxCast Phase-I library in concentration-response format (0.05–50 µM) using this HCS assay. Based on this screen, we identified butafenacil as a potent inducer of anemia, as exposure from 0.39 to 3.125 µM butafenacil completely abolished arterial circulation in the absence of effects on all other endpoints evaluated. Butafenacil is an herbicide that inhibits protoporphyrinogen oxidase (PPO) – an enzyme necessary for heme production in vertebrates. Using o-dianisidine staining, we then revealed that severe butafenacil-induced anemia in zebrafish was due to a complete loss of hemoglobin following exposure during early development. Therefore, six additional PPO inhibitors within the ToxCast Phase-I library were screened to determine whether anemia represents a common adverse outcome for these herbicides. Embryonic exposure to only one of these PPO inhibitors – flumioxazin – resulted in a similar phenotype as butafenacil, albeit not as severe as butafenacil. Overall, this study highlights the potential utility of this assay for (1) screening chemicals for cardiovascular toxicity and (2) prioritizing chemicals for future hypothesis-driven and mechanism-focused investigations within zebrafish and mammalian models. PMID:25090246

Erosion modeling and test of slip-cast fused silica

NASA Astrophysics Data System (ADS)

Weiskopf, Francis B., Jr.; Lin, Jeffrey S.; Drobnick, Rudy A.; Feather, Brian K.

1990-10-01

This paper summarizes a test program to verify the Balageas erosion model for Slip Cast Fused Silica in a flight-like erosive environment. The test program is summarized with particular attention paid to documenting the erosive environment. The Balageas model was found to over predict the erosion for these tests and a revised model which gives reasonable agreement with the data is proposed.

Measuring cannabis consumption: Psychometric properties of the Daily Sessions, Frequency, Age of Onset, and Quantity of Cannabis Use Inventory (DFAQ-CU)

PubMed Central

Spradlin, Alexander

2017-01-01

Objective We created the Daily Sessions, Frequency, Age of Onset, and Quantity of Cannabis Use Inventory (DFAQ-CU) because the current lack of psychometrically sound inventories for measuring these dimensions of cannabis use has impeded research on the effects of cannabis in humans. Method A sample of 2,062 cannabis users completed the DFAQ-CU and was used to assess the DFAQ-CU’s factor structure and reliability. To assess validity, a subsample of 645 participants completed additional measures of cannabis dependence and problems (Marijuana Smoking History Questionnaire [MSHQ], Timeline Followback [TLFB], Cannabis Abuse Screening Test [CAST], Cannabis Use Disorders Identification Test Revised [CUDIT-R], Cannabis Use Problems Identification Test [CUPIT], and Alcohol Use Disorder Identification Test [AUDIT]). Results A six-factor structure was revealed, with factors measuring: daily sessions, frequency, age of onset, marijuana quantity, cannabis concentrate quantity, and edibles quantity. The factors were reliable, with Cronbach’s alpha coefficients ranging from .69 (daily sessions) to .95 (frequency). Results further provided evidence for the factors’ convergent (MSHQ, TLFB), predictive (CAST, CUDIT-R, CUPIT), and discriminant validity (AUDIT). Conclusions The DFAQ-CU is the first psychometrically sound inventory for measuring frequency, age of onset, and quantity of cannabis use. It contains pictures of marijuana to facilitate the measurement of quantity of marijuana used, as well as questions to assess the use of different forms of cannabis (e.g., concentrates, edibles), methods of administering cannabis (e.g., joints, hand pipes, vaporizers), and typical THC levels. As such, the DFAQ-CU should help facilitate research on frequency, quantity, and age of onset of cannabis use. PMID:28552942

Generation and evaluation of 3D digital casts of maxillary defects based on multisource data registration: A pilot clinical study.

PubMed

Ye, Hongqiang; Ma, Qijun; Hou, Yuezhong; Li, Man; Zhou, Yongsheng

2017-12-01

Digital techniques are not clinically applied for 1-piece maxillary prostheses containing an obturator and removable partial denture retained by the remaining teeth because of the difficulty in obtaining sufficiently accurate 3-dimensional (3D) images. The purpose of this pilot clinical study was to generate 3D digital casts of maxillary defects, including the defective region and the maxillary dentition, based on multisource data registration and to evaluate their effectiveness. Twelve participants with maxillary defects were selected. The maxillofacial region was scanned with spiral computer tomography (CT), and the maxillary arch and palate were scanned using an intraoral optical scanner. The 3D images from the CT and intraoral scanner were registered and merged to form a 3D digital cast of the maxillary defect containing the anatomic structures needed for the maxillary prosthesis. This included the defect cavity, maxillary dentition, and palate. Traditional silicone impressions were also made, and stone casts were poured. The accuracy of the digital cast in comparison with that of the stone cast was evaluated by measuring the distance between 4 anatomic landmarks. Differences and consistencies were assessed using paired Student t tests and the intraclass correlation coefficient (ICC). In 3 participants, physical resin casts were produced by rapid prototyping from digital casts. Based on the resin casts, maxillary prostheses were fabricated by using conventional methods and then evaluated in the participants to assess the clinical applicability of the digital casts. Digital casts of the maxillary defects were generated and contained all the anatomic details needed for the maxillary prosthesis. Comparing the digital and stone casts, a paired Student t test indicated that differences in the linear distances between landmarks were not statistically significant (P>.05). High ICC values (0.977 to 0.998) for the interlandmark distances further indicated the high degree of consistency between the digital and stone casts. The maxillary prostheses showed good clinical effectiveness, indicating that the corresponding digital casts met the requirements for clinical application. Based on multisource data from spiral CT and the intraoral scanner, 3D digital casts of maxillary defects were generated using the registration technique. These casts were consistent with conventional stone casts in terms of accuracy and were suitable for clinical use. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Comparative study of the surface characteristics, microstructure, and magnetic retentive forces of laser-welded dowel-keepers and cast dowel-keepers for use with magnetic attachments.

PubMed

Chao, Yonglie; Du, Li; Yang, Ling

2005-05-01

Information regarding the merits and problems associated with connecting a keeper to a dowel and coping using a laser welding technique has not been explored extensively in the dental literature. This in vitro study compared the surface characteristics, microstructure, and magnetic retentive forces for a dowel and coping-keeper mechanism fabricated using a laser welding process and a cast-to casting technique. Five cast-to and 6 laser-welded dowel and coping-keeper specimens were tested. Using 5 freestanding keepers as the control group, the surface characteristics and microstructures of the specimens were examined by means of stereomicroscopy, metallographic microscopy, and scanning electron microscopy (SEM). Energy-dispersive spectroscopic (EDS) microanalysis with SEM provided elemental concentration information for the test specimens. The vertical magnetic retentive forces (N) of the 3 groups were measured using a universal testing machine. The results were statistically compared using 1-way analysis of variance and the Newman-Keuls multiple range test (alpha =.05). The laser-welded dowel-keeper generally maintained its original surface smoothness as well as the original microstructure. Elements diffused readily through the fusion zone. The surface of the cast dowel-keeper became rough with the formation of an oxide layer, the microstructure changed, and there was only limited elemental diffusion in the fusion zone. The average vertical magnetic retentive force of the laser-welded group, the cast group, and the control group were 4.2 +/- 0.2 N, 3.8 +/- 0.3 N, and 5.6 +/- 0.3 N, respectively. Statistically significant differences in vertical magnetic retentive force were found between the control group and both the laser-welded and cast groups (P <.01). Compared with the cast dowel-keepers, the average vertical magnetic retentive force of the laser-welded dowel-keepers was significantly higher (P <.05). The laser welding technique had less influence on the surface characteristics, the microstructure, and the magnetic retentive forces of keepers relative to techniques that incorporate a keeper at the time of cast dowel and coping fabrication.

An Evaluation of LH-Stimulated Testosterone Production by ...

EPA Pesticide Factsheets

An Evaluation of LH-Stimulated Testosterone Production by Highly Purified Rat Leydig Cells: A Complementary Screen for Steroidogenesis in the Testis. 1Botteri, N., 2Suarez, J., 2Laws, S., 2Klinefelter, G.1Oak Ridge Institute for Science and Education, Oak Ridge, TN, 2 U.S. Environmental Protection Agency, ORD, NHEERL, TAD, RTP, NCThe H295R steroidogenesis assay uses an adrenocarcinoma cell line which fails to elicit LH mediated responses. This limits the assay’s ability to detect chemicals which disrupt LH-mediated Leydig cell responses in the testis. This study evaluated whether LH-stimulated T production by purified rat Leydig cells would be altered after exposure to chemicals that failed to decrease T production in the ToxCast H295R screen. Ten chemicals negative for T inhibition in the H295R screen, were selected based on alterations in upstream substrates (deoxycorticosterone, hydroxyprogesterone) expected to result in a decrease in T. Based on earlier work, simvastatin served as our positive control. Each chemical was tested over 6 concentrations ranging from 0.1 µM to 100 µM. Leydig cells were cultured overnight under maximal LH stimulation. A minimum of 3 replicate experiments were conducted for each format (24 and 96 well) and chemical tested; cell viability was assessed using a live/dead cytotoxicity kit. T data were excluded if viability was less than 80% of control. Initial evaluation using a 24-well Leydig cell assay confir

Application of powder metallurgy technique to produce improved bearing elements for cryogenic aerospace engine turbopumps

NASA Technical Reports Server (NTRS)

Moxson, V. S.; Moracz, D. J.; Bhat, B. N.; Dolan, F. J.; Thom, R.

1987-01-01

Traditionally, vacuum melted 440C stainless steel is used for high performance bearings for aerospace cryogenic systems where corrosion due to condensation is a major concern. For the Space Shuttle Main Engine (SSME), however, 440C performance in the high-pressure turbopumps has been marginal. A basic assumption of this study was that powder metallurgy, rather than cast/wrought, processing would provide the finest, most homogeneous bearing alloy structure. Preliminary testing of P/M alloys (hardness, corrosion resistance, wear resistance, fatigue resistance, and fracture toughness) was used to 'de-select' alloys which did perform as well as baseline 440C. Five out of eleven candidate materials (14-4/6V, X-405, MRC-2001, T-440V, and D-5) based on preliminary screening were selected for the actual rolling-sliding five-ball testing. The results of this test were compared with high-performance vacuum-melted M50 bearing steel. The results of the testing indicated outstanding performance of two P/M alloys, X-405 and MRC-2001, which eventually will be further evaluated by full-scale bearing testing.

Experimental analysis of volumetric wear behavioural and mechanical properties study of as cast and 1Hr homogenized Al-25Mg2Si2Cu4Ni alloy at constant load

NASA Astrophysics Data System (ADS)

Harlapur, M. D.; Mallapur, D. G.; Udupa, K. Rajendra

2018-04-01

In the current study, an experimental analysis of volumetric wear behaviour and mechanical properties of aluminium (Al-25Mg2Si2Cu4Ni) alloy in as cast and 1Hr homogenized with T6 heat treatment is carried out at constant load. Pin-on-disc apparatus was used to carry out sliding wear test. Mechanical properties such as tensile, hardness and compression test on as-cast and 1 hr homogenized samples are measured. Universal testing machine was used to conduct the tensile and compressive test at room temperature. Brinell hardness tester was used to conduct the hardness test. The scanning electron microscope was used to analyze the worn-out wear surfaces. Wear results and mechanical properties shows that 1Hr homogenized Al-25Mg2Si2Cu4Ni alloy samples with T6 treated had better volumetric wear resistance, hardness, tensile and compressive strength as compared to as cast samples.

Effect of investment type and mold temperature on casting accuracy and titanium-ceramic bond.

PubMed

Leal, Mônica Barbosa; Pagnano, Valéria Oliveira; Bezzon, Osvaldo Luiz

2013-01-01

This study evaluated the casting accuracy of crown margins and metal-ceramic shear bond strength (SBS) of pure titanium injected into casting molds made using 2 investment types at 3 mold temperatures. Sixty crown (30-degree beveled finish line) and 60 cylinder (5mm diameter × 8mm high) patterns were divided into 6 groups (n=10), and cast using a phosphate-bonded investment (P) and a magnesium oxide-bonded investment (U), at 400°C (groups P400 and U400), 550°C (groups P550 and U550) and 700°C (groups P700 and U700) mold temperatures. Crown margins were recorded in impression material, the degree of marginal rounding was measured and margin length deficiencies (µm) were calculated. Titanium-ceramic specimens were prepared using Triceram ceramic (2mm high) and SBS was tested. Failure modes were assessed by optical microscopy. Data were subjected to two-way ANOVA and Tukey's HSD test (α=0.05). For casting accuracy, expressed by marginal deficiency (µm), investment U provided more accurate results (64 ± 11) than P (81 ± 23) (p<0.001). The increase in temperature resulted in different effects for the tested investments (p<0.001), as it provided better casting accuracy for U700 (55 ± 7) and worse for P700 (109 ± 18). Casting accuracy at 700°C (82 ± 31) was significantly different from 400°C (69 ± 9) and 550°C (68 ± 9) (p<0.05). For SBS, there was no significant differences among the groups for factors investment (p=0.062) and temperature (p=0.224), or for their interaction (p=0.149). Investment U provided better casting accuracy than investment P. The SBS was similar for all combinations of investments and temperatures.

49 CFR 192.487 - Remedial measures: Distribution lines other than cast iron or ductile iron lines.

Code of Federal Regulations, 2011 CFR

2011-10-01

... STANDARDS Requirements for Corrosion Control § 192.487 Remedial measures: Distribution lines other than cast iron or ductile iron lines. (a) General corrosion. Except for cast iron or ductile iron pipe, each... engineering tests and analyses show can permanently restore the serviceability of the pipe. Corrosion pitting...

49 CFR 192.487 - Remedial measures: Distribution lines other than cast iron or ductile iron lines.

Code of Federal Regulations, 2013 CFR

2013-10-01

... STANDARDS Requirements for Corrosion Control § 192.487 Remedial measures: Distribution lines other than cast iron or ductile iron lines. (a) General corrosion. Except for cast iron or ductile iron pipe, each... engineering tests and analyses show can permanently restore the serviceability of the pipe. Corrosion pitting...

49 CFR 192.487 - Remedial measures: Distribution lines other than cast iron or ductile iron lines.

Code of Federal Regulations, 2012 CFR

2012-10-01

... STANDARDS Requirements for Corrosion Control § 192.487 Remedial measures: Distribution lines other than cast iron or ductile iron lines. (a) General corrosion. Except for cast iron or ductile iron pipe, each... engineering tests and analyses show can permanently restore the serviceability of the pipe. Corrosion pitting...

49 CFR 192.487 - Remedial measures: Distribution lines other than cast iron or ductile iron lines.

Code of Federal Regulations, 2014 CFR

2014-10-01

... STANDARDS Requirements for Corrosion Control § 192.487 Remedial measures: Distribution lines other than cast iron or ductile iron lines. (a) General corrosion. Except for cast iron or ductile iron pipe, each... engineering tests and analyses show can permanently restore the serviceability of the pipe. Corrosion pitting...

Notched bar Izod impact properties of zinc die castings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schrems, K.K.; Dogan, O.N.; Goodwin, F.E.

2007-03-01

Notched bar Izod impact testing of zinc die cast Alloy 3, Alloy 5, ZA-8, and AcuZinc 5 was performed at five temperatures between -40\\mDC and room temperature in accordance with ASTM E23 for impact testing of metallic materials. A direct comparison between ASTM D256 for impact testing of plastics and ASTM E23 was performed using continuously cast zinc specimens of Alloy 5 and ZA-8 at -40\\mDC and room temperature. There are differences in sample sizes, impact velocity, and striker geometry between the two tests. Bulk zinc tested according to ASTM E23 resulted in higher impact energies at -40\\mDC and lowermore » impact energies at room temperature then did the same alloys when tested according to ASTM D256.« less

Children's and adults' reactions to magical and ordinary suggestion: are suggestibility and magical thinking psychologically close relatives?

PubMed

Subbotsky, Eugene

2007-11-01

In Experiment 1, 6- and 9-year-old children and adults were asked to imagine various types of objects. The experimenter then attempted to change the image of those objects in participants' minds by either suggesting that the objects may change against the participants' will, or by asking participants to change the objects as a favor to the experimenter. Two types of suggestive causation were employed: Magical-suggestion (a magic spell was cast with the aim of changing the imagined objects) and ordinary-suggestion (participants were told that the objects in their minds could alter against their will). Ordinary-suggestion was as effective as magical-suggestion in changing the participants' imagined objects. For adults, a direct request for compliance produced a stronger effect than did magical suggestion. This effect was not found in children. In Experiment 2, the two types of suggestion were tested on an alternative type of imagined objects. Adult participants were asked to imagine their futures. It was then proposed that (a) a magic spell could be cast on their futures with the aim of changing them either for the worse or for the better (magical-suggestion), or (b) changing a numerical pattern on a computer screen could change their futures (ordinary-suggestion). All participants denied that changing a numerical pattern on a computer screen could affect their lives, yet in their actions they demonstrated an element of belief in this possibility. As in Experiment 1, in Experiment 2 ordinary suggestion was as effective as magical suggestion. The hypothesis of an historic contiguity between magical causality and ordinary suggestion is discussed.

Comparative study of two commercially pure titanium casting methods

PubMed Central

RODRIGUES, Renata Cristina Silveira; FARIA, Adriana Claudia Lapria; ORSI, Iara Augusta; de MATTOS, Maria da Gloria Chiarello; MACEDO, Ana Paula; RIBEIRO, Ricardo Faria

2010-01-01

The interest in using titanium to fabricate removable partial denture (RPD) frameworks has increased, but there are few studies evaluating the effects of casting methods on clasp behavior. Objective This study compared the occurrence of porosities and the retentive force of commercially pure titanium (CP Ti) and cobalt-chromium (Co-Cr) removable partial denture circumferential clasps cast by induction/centrifugation and plasma/vacuum-pressure. Material and Methods 72 frameworks were cast from CP Ti (n=36) and Co-Cr alloy (n=36; control group). For each material, 18 frameworks were casted by electromagnetic induction and injected by centrifugation, whereas the other 18 were casted by plasma and injected by vacuum-pressure. For each casting method, three subgroups (n=6) were formed: 0.25 mm, 0.50 mm, and 0.75 mm undercuts. The specimens were radiographed and subjected to an insertion/removal test simulating 5 years of framework use. Data were analyzed by ANOVA and Tukey's to compare materials and cast methods (α=0.05). Results Three of 18 specimens of the induction/centrifugation group and 9 of 18 specimens of plasma/vacuum-pressure cast presented porosities, but only 1 and 7 specimens, respectively, were rejected for simulation test. For Co-Cr alloy, no defects were found. Comparing the casting methods, statistically significant differences (p<0.05) were observed only for the Co-Cr alloy with 0.25 mm and 0.50 mm undercuts. Significant differences were found for the 0.25 mm and 0.75 mm undercuts dependent on the material used. For the 0.50 mm undercut, significant differences were found when the materials were induction casted. Conclusion Although both casting methods produced satisfactory CP Ti RPD frameworks, the occurrence of porosities was greater in the plasma/vacuum-pressure than in the induction/centrifugation method, the latter resulting in higher clasp rigidity, generating higher retention force values. PMID:21085805

The Indian origin of paternal haplogroup R1a1* substantiates the autochthonous origin of Brahmins and the caste system.

PubMed

Sharma, Swarkar; Rai, Ekta; Sharma, Prithviraj; Jena, Mamata; Singh, Shweta; Darvishi, Katayoon; Bhat, Audesh K; Bhanwer, A J S; Tiwari, Pramod Kumar; Bamezai, Rameshwar N K

2009-01-01

Many major rival models of the origin of the Hindu caste system co-exist despite extensive studies, each with associated genetic evidences. One of the major factors that has still kept the origin of the Indian caste system obscure is the unresolved question of the origin of Y-haplogroup R1a1*, at times associated with a male-mediated major genetic influx from Central Asia or Eurasia, which has contributed to the higher castes in India. Y-haplogroup R1a1* has a widespread distribution and high frequency across Eurasia, Central Asia and the Indian subcontinent, with scanty reports of its ancestral (R*, R1* and R1a*) and derived lineages (R1a1a, R1a1b and R1a1c). To resolve these issues, we screened 621 Y-chromosomes (of Brahmins occupying the upper-most caste position and schedule castes/tribals occupying the lower-most positions) with 55 Y-chromosomal binary markers and seven Y-microsatellite markers and compiled an extensive dataset of 2809 Y-chromosomes (681 Brahmins, and 2128 tribals and schedule castes) for conclusions. A peculiar observation of the highest frequency (up to 72.22%) of Y-haplogroup R1a1* in Brahmins hinted at its presence as a founder lineage for this caste group. Further, observation of R1a1* in different tribal population groups, existence of Y-haplogroup R1a* in ancestors and extended phylogenetic analyses of the pooled dataset of 530 Indians, 224 Pakistanis and 276 Central Asians and Eurasians bearing the R1a1* haplogroup supported the autochthonous origin of R1a1 lineage in India and a tribal link to Indian Brahmins. However, it is important to discover novel Y-chromosomal binary marker(s) for a higher resolution of R1a1* and confirm the present conclusions.

Creep fatigue life prediction for engine hot section materials (isotropic)

NASA Technical Reports Server (NTRS)

Nelson, R. S.; Levan, G. W.; Schoendorf, J. F.

1992-01-01

A series of high temperature strain controlled fatigue tests have been completed to study the effects of thermomechanical fatigue, multiaxial loading, reactive environments, and imposed mean stresses. The baseline alloy used in these tests was cast B1900+Hf (with and without coatings); a small number of tests of wrought INCO 718 are also included. A strong path dependence was demonstrated during the thermomechanical fatigue testing, using in-phase, out-phase, and non-proportional (elliptical and 'dogleg') strain-temperature cycles. The multiaxial tests also demonstrated cycle path to be a significant variable, using both proportional and non-proportional tension-torsion loading. Environmental screening tests were conducted in moderate pressure oxygen and purified argon; the oxygen reduced the specimen lives by two, while the argon testing produced ambiguous data. Both NiCoCrAlY overlay and diffusion aluminide coatings were evaluated under isothermal and TMF conditions; in general, the lives of the coated specimens were higher that those of uncoated specimens. Controlled mean stress TMF tests showed that small mean stress changes could change initiation lives by orders of magnitude; these results are not conservatively predicted using traditional linear damage summation rules. Microstructures were evaluated using optical, SEM and TEM methods.

Screening and identification of aerobic denitrifiers

NASA Astrophysics Data System (ADS)

Shao, K.; Deng, H. M.; Chen, Y. T.; Zhou, H. J.; Yan, G. X.

2016-08-01

With the standards of the effluent quality more stringent, it becomes a quite serious problem for municipalities and industries to remove nitrogen from wastewater. Bioremediation is a potential method for the removal of nitrogen and other pollutants because of its high efficiency and low cost. Seven predominant aerobic denitrifiers were screened and characterized from the activated sludge in the CAST unit. Some of these strains removed 87% nitrate nitrogen at least. Based on their phenotypic and phylogenetic characteristics, the isolates were identified as the genera of Ralstonia, Achromobacter, Aeromonas and Enterobacter.

A prospective study on the effectiveness of cotton versus waterproof cast padding in maintaining the reduction of pediatric distal forearm fractures.

PubMed

Robert, Christopher E; Jiang, Jimmy J; Khoury, Joseph G

2011-03-01

Distal forearm fractures, one of the most common fractures seen in the pediatric population, are regularly treated by closed reduction and casting. Our study investigates the effectiveness of Gore-Tex-lined casting in maintaining the reduction of 100% displaced distal forearm fractures compared with traditional cotton-lined casts. We screened all patients from February 2007 to July 2009 who presented to Children's Hospital in Birmingham, AL with a distal radius fracture. Only patients with 100% displaced distal radius fractures were eligible to be assigned to either the cotton-lined or Gore-Tex-lined cast groups. Power analysis was performed to identify an adequate patient sample size. The mean maximum change between initial post-reduction x-rays and follow-up x-rays for anterior-posterior (AP) angulation, AP displacement, lateral angulation, and lateral displacement of the radius were calculated for both cotton and Gore-Tex groups. The rate of subsequent intervention and/or unacceptable results for each group was also analyzed. Seven hundred and twenty-two patients were treated with distal radius fractures at our hospital with 59 patients eligible for inclusion in our study. Thirty-six of our patients were treated with cotton-lined casts, and 23 patients were treated with Gore-Tex-lined cast. The mean maximum change in AP angulation, AP displacement, lateral angulation, and lateral displacement of the radius after initial reduction was 9.2 degrees, 6.9%, 13.9 degrees, and 13.6%, respectively, for the cotton-lined cast group and 7.7 degrees, 6.1%, 14.6 degrees, and 9.6%, respectively, for the Gore-Tex-lined cast group. There were no statistical differences between the means of the 4 measurements (P=0.33, 0.69, 0.73, and 0.10, respectively). There were also no significant differences between groups for final AP and lateral angulation and displacement. Subgroup analysis showed no significant differences in all measurements between cotton and Gore-Tex groups. Gore-Tex and cotton-lined casts are equally effective in their ability to maintain the reduction of 100% displaced distal forearm fractures. Thus, Gore-Tex-lined casts can be offered to pediatric patients immediately after closed reduction of distal radius fractures of any severity. Therapeutic level II.

An alternative section method for casting and posterior laser welding of metallic frameworks for an implant-supported prosthesis.

PubMed

de Aguiar, Fábio Afrânio; Tiossi, Rodrigo; Rodrigues, Renata Cristina Silveira; Mattos, Maria de Gloria Chiarello; Ribeiro, Ricardo Faria

2009-04-01

The aim of this study was to compare the accuracy of fit of three types of implant-supported frameworks cast in Ni-Cr alloy: specifically, a framework cast as one piece compared to frameworks cast separately in sections to the transverse or the diagonal axis, and later laser welded. Three sets of similar implant-supported frameworks were constructed. The first group of six 3-unit implant-supported frameworks were cast as one piece, the second group of six were sectioned in the transverse axis of the pontic region prior to casting, and the last group of six were sectioned in the diagonal axis of the pontic region prior to casting. The sectioned frameworks were positioned in the matrix (10 N.cm torque) and laser welded. To evaluate passive fit, readings were made with an optical microscope with both screws tightened and with only one-screw tightened. Data were submitted to ANOVA and Tukey-Kramer's test (p < 0.05). When both screws were tightened, no differences were found between the three groups (p > 0.05). In the single-screw-tightened test, with readings made opposite to the tightened side, the group cast as one piece (57.02 +/- 33.48 mum) was significantly different (p < 0.05) from the group sectioned diagonally (18.92 +/- 4.75 microm) but no different (p > 0.05) from the group transversally sectioned (31.42 +/- 20.68 microm). On the tightened side, no significant differences were found between the groups (p > 0.05). Results of this study showed that casting diagonally sectioned frameworks lowers misfit levels of prosthetic implant-supported frameworks and also improves the levels of passivity to the same frameworks when compared to structures cast as one piece.

Early substance consumption and problematic use of video games in adolescence.

PubMed

Coëffec, Adélaïde; Romo, Lucia; Cheze, Nathalie; Riazuelo, Hélène; Plantey, Sophie; Kotbagi, Gayatri; Kern, Laurence

2015-01-01

Substance use as well as use of video games is frequent among young people. The purpose of this research was to study the links between the use of video games and the consumption of various substances such as alcohol, tobacco or cannabis at adolescence. In order to do so, 1423 students from middle and high schools filled an auto-questionnaire that included questions on age, gender, year of study, use of video games and consumptions of alcohol (Alcohol Use Disorders Identification Test Short version, AUDIT-C), tobacco (Heaviness of Smoking Index, HSI), and cannabis (Cannabis Abuse Screening Test, CAST). We found that 92.1% of teens use video games and 17.7% have a problematic use of video games (PUVG). Furthermore, results show that substance consumption seems frequent with 19.8 and 8.3% of participants having hazardous alcohol and cannabis consumptions respectively and 5.2% having a moderate to high tobacco dependence. Video gamers consumed significantly more alcohol and gamers with PUVG started their substance consumption (alcohol, tobacco, and cannabis) earlier. PUVG was found to be negatively correlated to age at first substance consumption, but positively correlated to the time spent playing video games. However, it was not correlated to risks of substance dependence (scores of AUDIT-C, HSI, and CAST). Finally, our results are consistent with the literature, in regard to frequency of substance use and use of video games in adolescence. These data will allow for a better consideration of prevention strategies and future care in this particular field.

Mechanical Testing of IN718 Lattice Block Structures

NASA Technical Reports Server (NTRS)

Krause, David L.; Whittenberger, John D.; Kantzos, Pete T.; Hebsur, Mohan G.

2002-01-01

Lattice block construction produces a flat, structurally rigid panel composed of thin ligaments of material arranged in a three-dimensional triangulated truss-like structure. Low-cost methods of producing cast metallic lattice block panels are now available that greatly expand opportunities for using this unique material system in today's high-performance structures. Additional advances are being made in NASA's Ultra Efficient Engine Technology (UEET) program to extend the lattice block concept to superalloy materials. Advantages offered by this combination include high strength, light weight, high stiffness, and elevated temperature capabilities. Recently under UEET, the nickel-based superalloy Inconel 718 (IN718) was investment cast into lattice block panels with great success. To evaluate casting quality and lattice block architecture merit, individual ligaments, and structural subelement specimens were extracted from the panels. Tensile tests, structural compression, and bending strength tests were performed on these specimens. Fatigue testing was also completed for several bend test specimens. This paper first presents metallurgical and optical microscopy analysis of the castings. This is followed by mechanical test results for the tensile ligament tests and the subelement compression and bending strength tests, as well as for the fatigue tests that were performed. These tests generally showed comparable properties to base IN718 with the same heat treatment, and they underscored the benefits offered by lattice block materials. These benefits might be extended with improved architecture such as face sheets.

Evaluation of the new TAMZ titanium alloy for dental cast application.

PubMed

Zhang, Y M; Guo, T W; Li, Z C

2000-12-01

To reveal the potential of the new titanium alloy as dental prosthodontic materials. Dental castings of TAMZ alloy were investigated in the casting machine specially designed for titanium. A mesh pattern was used to count the castability value. The mechanical properties were measured by means of a universal testing machine. Optical micrography was done on the exposed cross-section of TAMZ alloy casting. From the surface to the inner part the Knoop hardness in reacted layer of TAMZ alloy casting was measured. The structure and elemental analyses of the reacted layer were made by SEM and element line scanning observation. The castability value (Cv = 98%) and the tensile test (sigma b = 850 Mpa, sigma 0.2 = 575 Mpa, delta = 7.33%) data were collected. The castings microstructure showed main alpha phase and small beta phase. Knoop hardness in the surface reacted layer was greater than that in the inner part. From the SEM and element line scanning observation, there are three different layers in the surface reacted layer of the TAMZ alloy castings, and higher level of element of O, Al, Si and Zr were found in the reacted layer while the Si permeated deeper than others. TAMZ alloy can be accepted as a material for dental alloy in prosthodontics.

Electroslag Treatment of Liquid Cast Iron

NASA Astrophysics Data System (ADS)

Grachev, V. A.

2018-01-01

The processes that occur in the liquid metal-slag system during electroslag treatment of cast iron are studied from an electrochemical standpoint. The role of electrolysis in the electroslag process is shown, and a method for producing high-strength cast iron with globular graphite using electrolysis of a slag containing magnesium oxides and fluorides is proposed and tested.

Gender Representation and Social Justice: Ideology, Methodology and Smoke-Screens

ERIC Educational Resources Information Center

Lumby, Jacky

2011-01-01

A number of researchers have provided an overview of the progress of research focusing on gender and educational leadership/management in the twentieth and twenty-first centuries. Some cast studies of representation as an early phase overtaken by later concern with phenomenological and radical perspectives. More recently, a focus on women and…

FIELD DEMONSTRATION OF INNOVATIVE LEAK DETECTION/LOCATION TECHNOLOGIES COUPLED WITH WALL-THICKNESS SCREENING FOR WATER MAINS

EPA Science Inventory

The U.S. Environmental Protection Agency sponsored a large-scale field demonstration of innovative leak detection/location and condition assessment technologies on a 76-year old, 2,500-ft long, cement-lined, 24-in. cast iron water main in Louisville, KY from July through Septembe...

In Silico Prediction of Physicochemical Properties of Environmental Chemicals Using Molecular Fingerprints and Machine Learning

EPA Science Inventory

There are little available toxicity data on the vast majority of chemicals in commerce. High-throughput screening (HTS) studies, such as those being carried out by the U.S. Environmental Protection Agency (EPA) ToxCast program in partnership with the federal Tox21 research progra...

Identifying developmental toxicity pathways for a subset of ToxCast chemicals using human embryonic stem cells and metabolomics

EPA Science Inventory

Metabolomics analysis was performed on the supernatant of human embryonic stem (hES) cell cultures exposed to a blinded subset of 11 chemicals selected from the chemical library of EPA's ToxCast™ chemical screening and prioritization research project. Metabolites from hES cultur...

Differentiating pathway-specific from non-specific effects in high-throughput toxicity data: A foundation for prioritizing adverse outcome pathway development

EPA Science Inventory

The U.S. Environmental Protection Agency’s ToxCast program has screened thousands of chemicals for biological activity, primarily using high-throughput in vitro bioassays. Adverse outcome pathways (AOPs) offer a means to link pathway-specific biological activities with pote...

Differentiating pathway-based toxicity from non-specific effects in high throughput data: A foundation for prioritizing targets for AOP development.

EPA Science Inventory

The Environmental Protection Agency has implemented a high throughput screening program, ToxCast, to quickly evaluate large numbers of chemicals for their effects on hundreds of different biological targets. To understand how these measurements relate to adverse effects in an or...

From cell lines to tissues: extrapolation of transcriptional effects to human tissues (SOT)

EPA Science Inventory

A new suite of assays in the metabolically-competent, human hepatocyte-derived HepaRG cell line has been added to the ToxCast screening suite. For 1066 chemicals we have evaluated the chemical treatment-induced changes in expression for a diverse set of 93 genes representative of...

Differentiating high priority pathway-based toxicity from non-specific effects in high throughput toxicity data: A foundation for prioritizing AOP development.

EPA Science Inventory

The ToxCast chemical screening approach enables the rapid assessment of large numbers of chemicals for biological effects, primarily at the molecular level. Adverse outcome pathways (AOPs) offer a means to link biomolecular effects with potential adverse outcomes at the level of...

Human Pluripotent Stem Cell-Based Assay Predicts Developmental Toxicity Potential of ToxCast Chemicals (ACT meeting)

EPA Science Inventory

Worldwide initiatives to screen for toxicity potential among the thousands of chemicals currently in use require inexpensive and high-throughput in vitro models to meet their goals. The devTOX quickPredict platform is an in vitro human pluripotent stem cell-based assay used to as...

Screening the ToxCast Phase I, II, and e1K Chemical Libraries for Inhibition of Deiodinase Type 1,2 and 3 Enzyme Activity

EPA Science Inventory

Thyroid hormone (TH) signaling and homeostasis is dependent upon coordination of multiple key events including thyroidal iodide uptake and hormone synthesis, and peripheral metabolism and elimination. Deiodinase enzymes play an essential role in converting the pro-hormone thyroxi...

Screening of multiple potential control genes for use in caste and body region comparisons using RT-qPCR in Coptotermes formosanus

USDA-ARS?s Scientific Manuscript database

Formosan subterranean termites, Coptotermes formosanus, are an important world wide pest. Molecular gene expression is an important tool for understanding the physiology of organisms. The recent advancement of molecular tools for Coptotermes formosanus is leading to advancement of the understanding ...

Domain-Specific QSAR Models for Identifying Potential Estrogenic Activity of Phenols (FutureTox III)

EPA Science Inventory

Computational tools can be used for efficient evaluation of untested chemicals for their ability to disrupt the endocrine system. We have employed previously developed global QSAR models that were trained and validated on the ToxCast/Tox21 ER assay data for virtual screening of a...

A Biologically Informed Framework for the Analysis of the PPAR Signaling Pathway using a Bayesian Network

EPA Science Inventory

The US EPA’s ToxCastTM program seeks to combine advances in high-throughput screening technology with methodologies from statistics and computer science to develop high-throughput decision support tools for assessing chemical hazard and risk. To develop new methods of analysis of...

Evaluation of High-Throughput Chemical Exposure Models via Analysis of Matched Environmental and Biological Media Measurements

EPA Science Inventory

The U.S. EPA, under its ExpoCast program, is developing high-throughput near-field modeling methods to estimate human chemical exposure and to provide real-world context to high-throughput screening (HTS) hazard data. These novel modeling methods include reverse methods to infer ...

Accuracy and eligibility of CBCT to digitize dental plaster casts.

PubMed

Becker, Kathrin; Schmücker, Ulf; Schwarz, Frank; Drescher, Dieter

2018-05-01

Software-based dental planning requires digital casts and oftentimes cone-beam computed tomography (CBCT) radiography. However, buying a dedicated model digitizing device can be expensive and might not be required. The present study aimed to assess whether digital models derived from CBCT and models digitized using a dedicated optical device are of comparable accuracy. A total of 20 plaster casts were digitized with eight CBCT and five optical model digitizers. Corresponding models were superimposed using six control points and subsequent iterative closest point matching. Median distances were calculated among all registered models. Data were pooled per scanner and model. Boxplots were generated, and the paired t test, a Friedman test, and a post-hoc Nemenyi test were employed for statistical comparison. Results were found significant at p < 0.05. All CBCT devices allowed the digitization of plaster casts, but failed to reach the accuracy of the dedicated model digitizers (p < 0.001). Median distances between CBCT and optically digitized casts were 0.064 + - 0.005 mm. Qualitative differences among the CBCT systems were detected (χ 2  = 78.07, p < 0.001), and one CBCT providing a special plaster cast digitization mode was found superior to the competitors (p < 0.05). CBCT systems failed to reach the accuracy from optical digitizers, but within the limits of the study, accuracy appeared to be sufficient for digital planning and forensic purposes. Most CBCT systems enabled digitization of plaster casts, and accuracy was found sufficient for digital planning and storage purposes.

A new portable vibrator for plaster pouring: effect on the marginal fit at cylinder-abutment

PubMed Central

de ANDRADE, Pâmela Cândida Aires Ribas; LUTHI, Leonardo Flores; STANLEY, Kyle; CARDOSO, Antônio Carlos

2012-01-01

Objective The aim of this study was to test a new portable vibrator for plaster pouring (developed for this purpose), comparing the effect of its use on the accuracy of working cast of implant-supported restorations to the conventional vibrator. Material and methods From a master cast with 2 implants, 30 transfer moldings were made randomly and divided into three groups: Group I (GI): pouring performed in an outsourced dental laboratory with conventional plaster vibrator (10 casts), Group II (GII): pouring performed in the laboratory of the Federal University of Santa Catarina (UFSC) with conventional plaster vibrator (10 casts) and Group III (GIII): pouring performed with the portable vibrator fabricated for this study (10 casts). The position of the analogue and marginal adaptation of the infrastructure were verified by testing the single screw on the master model and on the working model. The measurement of misfit was blindly performed with a precision microscope and analyzing unit, Quadra-Check 200. The data were statistically analyzed by analysis of variance (ANOVA) and the Holm-Sidak test (α=0.05). Results Means±standard deviations were as follows: GI: 19.19±4.73 µm; GII: 21.72±5.41 µm; GIII: 13.5±2.39 µm (P<0.05), with GIII significantly lower as compared to the other groups. Conclusion Within the limitations of this study, it was concluded that a greater accuracy of working cast was achieved when a portable vibrator was used for casting molds. PMID:23138736

21st century tools to prioritize contaminants for monitoring and ...

EPA Pesticide Factsheets

The webinar focused on ways that ToxCast high throughput screening data and the adverse outcome pathway framework, under development in the CSS program, can be used to prioritize environmental contaminants for monitoring and management. The webinar focused on ways that ToxCast high throughput screening data and the adverse outcome pathway framework, under development in the CSS program, can be used to prioritize environmental contaminants for monitoring and management. The work presented focused on case studies conducted in Region 8, in collaboration with EPA Region 8 and NEIC, as well as other federal (USGS, US FWS) and regional partners (Northern Colorado Plateau Network). The Consortium for Research and Education on Emerging Contaminants (CREEC) is a grass-roots 501(c)(3) non-profit organization comprised of world-class scientists and stakeholders with a shared interest in the source, fate, and physiological effects of contaminants of emerging concern (www.creec.net). As such, they represent an important group of stakeholders with an interest in applying the data, approaches, and tools that are being developed by the CSS program.

Applying 21st century tools to watersheds of the western US ...

EPA Pesticide Factsheets

The webinar focused on ways that ToxCast high throughput screening data and the adverse outcome pathway framework, under development in the CSS program, can be used to prioritize environmental contaminants for monitoring and management. The webinar focused on ways that ToxCast high throughput screening data and the adverse outcome pathway framework, under development in the CSS program, can be used to prioritize environmental contaminants for monitoring and management. The work presented focused on case studies conducted in Region 8, in collaboration with EPA Region 8 and NEIC, as well as other federal (USGS, US FWS) and regional partners (Northern Colorado Plateau Network). The Consortium for Research and Education on Emerging Contaminants (CREEC) is a grass-roots 501(c)(3) non-profit organization comprised of world-class scientists and stakeholders with a shared interest in the source, fate, and physiological effects of contaminants of emerging concern (www.creec.net). As such, they represent an important group of stakeholders with an interest in applying the data, approaches, and tools that are being developed by the CSS program.

Identifying Metabolically Active Chemicals Using a Consensus ...

EPA Pesticide Factsheets

Traditional toxicity testing provides insight into the mechanisms underlying toxicological responses but requires a high investment in a large number of resources. The new paradigm of testing approaches involves rapid screening studies able to evaluate thousands of chemicals across hundreds of biological targets through use of in vitro assays. Endocrine disrupting chemicals (EDCs) are of concern due to their ability to alter neurodevelopment, behavior, and reproductive success of humans and other species. A recent integrated computational model examined results across 18 ER-related assays in the ToxCast in vitro screening program to eliminate chemicals that produce a false signal by possibly interfering with the technological attributes of an individual assay. However, in vitro assays can also lead to false negatives when the complex metabolic processes that render a chemical bioactive in a living system might be unable to be replicated in an in vitro environment. In the current study, the influence of metabolism was examined for over 1,400 chemicals considered inactive using the integrated computational model. Over 2,000 first-generation and over 4,000 second-generation metabolites were generated for the inactive chemicals using in silico techniques. Next, a consensus model comprised of individual structure activity relationship (SAR) models was used to predict ER-binding activity for each of the metabolites. Binding activity was predicted for 8-10% of the meta

TOXCAST, A TOOL FOR CATEGORIZATION AND ...

EPA Pesticide Factsheets

Across several EPA Program Offices (e.g., OPPTS, OW, OAR), there is a clear need to develop strategies and methods to screen large numbers of chemicals for potential toxicity, and to use the resulting information to prioritize the use of testing resources towards those entities and endpoints that present the greatest likelihood of risk to human health and the environment. This need could be addressed using the experience of the pharmaceutical industry in the use of advanced modern molecular biology and computational chemistry tools for the development of new drugs, with appropriate adjustment to the needs and desires of environmental toxicology. A conceptual approach named ToxCast has been developed to address the needs of EPA Program Offices in the area of prioritization and screening. Modern computational chemistry and molecular biology tools bring enabling technologies forward that can provide information about the physical and biological properties of large numbers of chemicals. The essence of the proposal is to conduct a demonstration project based upon a rich toxicological database (e.g., registered pesticides, or the chemicals tested in the NTP bioassay program), select a fairly large number (50-100 or more chemicals) representative of a number of differing structural classes and phenotypic outcomes (e.g., carcinogens, reproductive toxicants, neurotoxicants), and evaluate them across a broad spectrum of information domains that modern technology has pro

Application of High-Throughput In Vitro Assays for Risk-Based ...

EPA Pesticide Factsheets

Multiple drivers shape the types of human-health assessments performed on chemicals by U.S. EPA resulting in chemical assessments are “fit-for-purpose” ranging from prioritization for further testing to full risk assessments. Layered on top of the diverse assessment needs are the resource intensive nature of traditional toxicological studies used to test chemicals and the lack of toxicity information on many chemicals. To address these challenges, the Agency initiated the ToxCast program to screen thousands of chemicals across hundreds of high-throughput screening assays in concentrations-response format. One of the findings of the project has been that the majority of chemicals interact with multiple biological targets within a narrow concentration range and the extent of interactions increases rapidly near the concentration causing cytotoxicity. This means that application of high-throughput in vitro assays to chemical assessments will need to identify both the relative selectivity at chemicals interact with biological targets and the concentration at which these interactions perturb signaling pathways. The integrated analyses will be used to both define a point-of-departure for comparison with human exposure estimates and identify which chemicals may benefit from further studies in a mode-of-action or adverse outcome pathway framework. The application of new technologies in a risk-based, tiered manner provides flexibility in matching throughput and cos

20150325 - Application of High-Throughput In Vitro Assays for ...

EPA Pesticide Factsheets

Multiple drivers shape the types of human-health assessments performed on chemicals by U.S. EPA resulting in chemical assessments are “fit-for-purpose” ranging from prioritization for further testing to full risk assessments. Layered on top of the diverse assessment needs are the resource intensive nature of traditional toxicological studies used to test chemicals and the lack of toxicity information on many chemicals. To address these challenges, the Agency initiated the ToxCast program to screen thousands of chemicals across hundreds of high-throughput screening assays in concentrations-response format. One of the findings of the project has been that the majority of chemicals interact with multiple biological targets within a narrow concentration range and the extent of interactions increases rapidly near the concentration causing cytotoxicity. This means that application of high-throughput in vitro assays to chemical assessments will need to identify both the relative selectivity at chemicals interact with biological targets and the concentration at which these interactions perturb signaling pathways. The integrated analyses will be used to both define a point-of-departure for comparison with human exposure estimates and identify which chemicals may benefit from further studies in a mode-of-action or adverse outcome pathway framework. The application of new technologies in a risk-based, tiered manner provides flexibility in matching throughput and cos

Effect of pressure of helium, argon, krypton, and xenon on the porosity, microstructure, and mechanical properties of commercially pure titanium castings.

PubMed

Zinelis, S

2000-11-01

Porosity is a frequently observed casting defect in dental titanium alloys. This study evaluated the effect of pressure of helium, argon, krypton, and xenon on the porosity, microstructure, and mechanical properties of commercially pure titanium (cp Ti) castings. Eight groups (A-H) of 16 rectangular wax patterns each (30 mm in length, 3 mm in width, and 1 mm in depth) were prepared. The wax patterns were invested with a magnesia-based material and cast with cp Ti (grade II). Groups A, C, E, and G were cast under a pressure of 1 atm, and groups B, D, F, and H were cast under a pressure of 0.5 atm of He, Ar, Kr, and Xe, respectively. The extent of the porosity of the cast specimens was determined radiographically and quantified by image analysis. Three specimens of each group and 3 cylinders of the as-received cp Ti used as a reference were embedded in resin and studied metallographically after grinding, polishing, and chemical etching. These surfaces were used for determination of the Vickers hardness (VHN) as well. Eight specimens from each group were fractured in the tensile mode, and the 0.2% yield strength, fracture stress, and percentage elongation were calculated. Porosity was analyzed with 2-way ANOVA and the Newman-Keuls multiple range test. VHN measurements and tensile properties for specimen groups were compared with 1-way ANOVA and the Newman-Keuls multiple range test (95% significance level). The porosity levels per group were (%): A = 5.50 +/- 4.34, B = 0.77 +/- 1.27, C = 2.44 +/- 3.68, D = 0.06 +/- 0.12, E-H = 0. Two-way ANOVA showed that there was no detectable interaction (P<.05) between gas type and applied pressure. Metallographic examination revealed no differences in microstructure among the groups studied. A finer grain size was observed in all cast groups compared with the original cp Ti. The VHN of the as-received cp Ti was significantly greater than all the cast groups tested. Groups cast under He showed the highest VHN, yield strength, and fracture stress. No significant differences were found in percentage elongation values among the groups. Porosity and mechanical properties of cp Ti castings are dependent on the gas type and pressure, whereas the microstructure remains unaffected.

Comparison of wear behaviour and mechanical properties of as-cast Al6082 and Al6082-T6 using statistical analysis

NASA Astrophysics Data System (ADS)

Rani Rana, Sandhya; Pattnaik, A. B.; Patnaik, S. C.

2018-03-01

In the present work the wear behavior and mechanical properties of as cast A16082 and A16086-T6 were compared and analyzed using statistical analysis. The as cast Al6082 alloy was solutionized at 550°C, quenched and artificially aged at 170°C for 8hrs. Metallographic examination and XRD analysis revealed the presence of intermetallic compounds Al6Mn.Hardness of heat treated Al6082 was found to be more than as cast sample. Wear tests were carried out using Pin on Disc wear testing machine according to Taguchi L9 orthogonal array. Experiments were conducted under normal load 10-30N, sliding speed 1-3m/s, sliding distance 400,800,1200m respectively. Sliding speed was found to be the dominant factor for wear in both as cast and aged Al 6082 alloy. Sliding distance increases the wear rate up to 800m and then after it decreases.

A Comparative Study of Hot Deformation Behaviors for Sand Casting and Centrifugal Casting Q235B Flange Blanks

NASA Astrophysics Data System (ADS)

Qin, Fangcheng; Li, Yongtang; Ju, Li

2017-03-01

Hot compression tests of sand casting and centrifugal casting Q235B flange blanks were performed at strain rate range of 0.01-5 s-1 and temperature range of 850-1,150 °C. The evolutions of microstructure and texture were revealed. The constitutive models based on Arrhenius constitutive modeling were proposed by considering the effects of strain on material constants. The results show that recrystallization in centrifugal casting Q235B is more apparent than that in sand casting, resulting in the finer grains and lower flow stress for centrifugal casting Q235B. The intensities of textures slightly weaken with the increase of temperature. At 1,050 °C and 5 s-1, the textures of sand casting are characterized by strong {001}<100> and {001}<110>, which are related with severe deformation, while the textures of centrifugal casting are composed of {110}<110> and {111}<112>, which are related with dynamic recovery and shear deformation. A good agreement between the predicted and experimental flow stress is achieved and demonstrates that the proposed constitutive models are reliable.

Development of a new casting method to fabricate U–Zr alloy containing minor actinides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jong Hwan Kim; Hoon Song; Hyung Tae Kim

2014-01-01

Metal fuel slugs of U–Zr alloys for a sodium-cooled fast reactor (SFR) have conventionally been fabricated using an injection casting method. However, casting alloys containing volatile radioactive constituents, such as Am, are problematic in a conventional injection casting method. As an alternative fabrication method, low pressure gravity casting has been developed. Casting soundness, microstructural characteristics, alloying composition, density, and fuel losses were evaluated for the following as-cast fuel slugs: U–10 wt% Zr, U–10 wt% Zr–5 wt% RE, and U–10 wt% Zr–5 wt% RE–5 wt% Mn. The U and Zr contents were uniform throughout the matrix, and impurities such as oxyen,more » carbon, and nitrogen satisfied the specification of total impurities less than 2,000 ppm. The appearance of the fuel slugs was generally sound, and the internal integrity was shown to be satisfactory based on gamma-ray radiography. In a volatile surrogate casting test, the U–Zr–RE–Mn fuel slug showed that nearly all of the manganese was retained when casting was done under an inert atmosphere.« less

Numerical simulation of the solidification microstructure of a 17-4PH stainless steel investment casting and its experimental verification

NASA Astrophysics Data System (ADS)

Li, You Yun; Tsai, DeChang; Hwang, Weng Sing

2008-06-01

The purpose of this study is to develop a technique of numerically simulating the microstructure of 17-4PH (precipitation hardening) stainless steel during investment casting. A cellular automation (CA) algorithm was adopted to simulate the nucleation and grain growth. First a calibration casting was made, and then by comparing the microstructures of the calibration casting with those simulated using different kinetic growth coefficients (a2, a3) in CA, the most appropriate set of values for a2 and a3 would be obtained. Then, this set of values was applied to the microstructure simulation of a separate casting, where the casting was actually made. Through this approach, this study has arrived at a set of growth kinetic coefficients from the calibration casting: a2 is 2.9 × 10-5, a3 is 1.49 × 10-7, which is then used to predict the microstructure of the other test casting. Consequently, a good correlation has been found between the microstructure of actual 17-4PH casting and the simulation result.

Aggregating Data for Computational Toxicology Applications ...

EPA Pesticide Factsheets

Computational toxicology combines data from high-throughput test methods, chemical structure analyses and other biological domains (e.g., genes, proteins, cells, tissues) with the goals of predicting and understanding the underlying mechanistic causes of chemical toxicity and for predicting toxicity of new chemicals and products. A key feature of such approaches is their reliance on knowledge extracted from large collections of data and data sets in computable formats. The U.S. Environmental Protection Agency (EPA) has developed a large data resource called ACToR (Aggregated Computational Toxicology Resource) to support these data-intensive efforts. ACToR comprises four main repositories: core ACToR (chemical identifiers and structures, and summary data on hazard, exposure, use, and other domains), ToxRefDB (Toxicity Reference Database, a compilation of detailed in vivo toxicity data from guideline studies), ExpoCastDB (detailed human exposure data from observational studies of selected chemicals), and ToxCastDB (data from high-throughput screening programs, including links to underlying biological information related to genes and pathways). The EPA DSSTox (Distributed Structure-Searchable Toxicity) program provides expert-reviewed chemical structures and associated information for these and other high-interest public inventories. Overall, the ACToR system contains information on about 400,000 chemicals from 1100 different sources. The entire system is built usi

Designing a Quantitative Structure-Activity Relationship for the ...

EPA Pesticide Factsheets

Toxicokinetic models serve a vital role in risk assessment by bridging the gap between chemical exposure and potentially toxic endpoints. While intrinsic metabolic clearance rates have a strong impact on toxicokinetics, limited data is available for environmentally relevant chemicals including nearly 8000 chemicals tested for in vitro bioactivity in the Tox21 program. To address this gap, a quantitative structure-activity relationship (QSAR) for intrinsic metabolic clearance rate was developed to offer reliable in silico predictions for a diverse array of chemicals. Models were constructed with curated in vitro assay data for both pharmaceutical-like chemicals (ChEMBL database) and environmentally relevant chemicals (ToxCast screening) from human liver microsomes (2176 from ChEMBL) and human hepatocytes (757 from ChEMBL and 332 from ToxCast). Due to variability in the experimental data, a binned approach was utilized to classify metabolic rates. Machine learning algorithms, such as random forest and k-nearest neighbor, were coupled with open source molecular descriptors and fingerprints to provide reasonable estimates of intrinsic metabolic clearance rates. Applicability domains defined the optimal chemical space for predictions, which covered environmental chemicals well. A reduced set of informative descriptors (including relative charge and lipophilicity) and a mixed training set of pharmaceuticals and environmentally relevant chemicals provided the best intr

High-Cycle Fatigue Resistance of Si-Mo Ductile Cast Iron as Affected by Temperature and Strain Rate

NASA Astrophysics Data System (ADS)

Matteis, Paolo; Scavino, Giorgio; Castello, Alessandro; Firrao, Donato

2015-09-01

Silicon-molybdenum ductile cast irons are used to fabricate exhaust manifolds of internal combustion engines of large series cars, where the maximum pointwise temperature at full engine load may be higher than 973 K (700 °C). In this application, high-temperature oxidation and thermo-mechanical fatigue (the latter being caused by the engine start and stop and by the variation of its power output) have been the subject of several studies and are well known, whereas little attention has been devoted to the high-cycle fatigue, arising from the engine vibration. Therefore, the mechanical behavior of Si-Mo cast iron is studied here by means of stress-life fatigue tests up to 10 million cycles, at temperatures gradually increasing up to 973 K (700 °C). The mechanical characterization is completed by tensile and compressive tests and ensuing fractographic examinations; the mechanical test results are correlated with the cast iron microstructure and heat treatment.

Evaluation of metal-ceramic bond characteristics of three dental Co-Cr alloys prepared with different fabrication techniques.

PubMed

Wang, Hongmei; Feng, Qing; Li, Ning; Xu, Sheng

2016-12-01

Limited information is available regarding the metal-ceramic bond strength of dental Co-Cr alloys fabricated by casting (CAST), computer numerical control (CNC) milling, and selective laser melting (SLM). The purpose of this in vitro study was to evaluate the metal-ceramic bond characteristics of 3 dental Co-Cr alloys fabricated by casting, computer numerical control milling, and selective laser melting techniques using the 3-point bend test (International Organization for Standardization [ISO] standard 9693). Forty-five specimens (25×3×0.5 mm) made of dental Co-Cr alloys were prepared by CAST, CNC milling, and SLM techniques. The morphology of the oxidation surface of metal specimens was evaluated by scanning electron microscopy (SEM). After porcelain application, the interfacial characterization was evaluated by SEM equipped with energy-dispersive spectrometry (EDS) analysis, and the metal-ceramic bond strength was assessed with the 3-point bend test. Failure type and elemental composition on the debonding interface were assessed by SEM/EDS. The bond strength was statistically analyzed by 1-way ANOVA and Tukey honest significant difference test (α=.05). The oxidation surfaces of the CAST, CNC, and SLM groups were different. They were porous in the CAST group but compact and irregular in the CNC and SLM groups. The metal-ceramic interfaces of the SLM and CNC groups showed excellent combination compared with those of the CAST group. The bond strength was 37.7 ±6.5 MPa for CAST, 43.3 ±9.2 MPa for CNC, and 46.8 ±5.1 MPa for the SLM group. Statistically significant differences were found among the 3 groups tested (P=.028). The debonding surfaces of all specimens exhibited cohesive failure mode. The oxidation surface morphologies and thicknesses of dental Co-Cr alloys are dependent on the different fabrication techniques used. The bond strength of all 3 groups exceed the minimum acceptable value of 25 MPa recommended by ISO 9693; hence, dental Co-Cr alloy fabricated with the SLM techniques could be a promising alternative for metal ceramic restorations. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Cast CF8C-Plus Stainless Steel for Turbocharger Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maziasz, P.J.; Shyam, A.; Evans, N.D.

2010-06-30

The purpose of this Cooperative Research and Development Agreement (CRADA) project is to provide the critical test data needed to qualify CF8C-Plus cast stainless steel for commercial production and use for turbocharger housings with upgraded performance and durability relative to standard commercial cast irons or stainless steels. The turbocharger technologies include, but are not limited to, heavy-duty highway diesel engines, and passenger vehicle diesel and gasoline engines. This CRADA provides additional critical high-temperature mechanical properties testing and data analysis needed to quality the new CF8C-Plus steels for turbocharger housing applications.

Application of the Attagene FACTORIAL™ assay to ...

EPA Pesticide Factsheets

Bioassays can be used to evaluate the integrated effects of complex mixtures from both known and unidentified contaminants present in environmental samples. However, such bio-monitoring approaches have typically focused only on one or a few pathways (e.g. estrogen receptor, androgen receptor) despite the fact that the chemicals in a mixture may exhibit a range of biological activities. High-throughput screening approaches that can rapidly assess samples for a broad diversity of biological activities offer a means to provide a more comprehensive characterization of complex mixtures. The Attagene FactorialTM platform is a high-throughput, cell based assay utilized by US EPA’s ToxCast Program, which provides high-content assessment of over 90 different gene regulatory pathways and all 48 human nuclear receptors (NRs). This assay has previously been used in a preliminary screening of surface water extracts from sites across the Great Lakes. In the current study, surface waters samples from 38 sites were collected, extracted, and screened through the Factorial assay as part of a USGS nationwide stream assessment. All samples were evaluated in a six point, 3-fold dilution series and analyzed using the ToxCast Data Pipeline (TCPL) to generate dose-response curves and corresponding half-maximal activity concentration (AC50) estimates. A total of 27 assay endpoints responded to extracts from one or more sites, with up to 14 assays active for a single extract. The four

ToxCast Profiling in a Human Stem Cell Assay for ...

EPA Pesticide Factsheets

Standard practice for assessing disruptions in embryogenesis involves testing pregnant animals of two species, typically rats and rabbits, exposed during major organogenesis and evaluated just prior to term. Under this design the major manifestations of developmental toxicity are observed as one or more apical endpoints including intrauterine death, fetal growth retardation, structural malformations and variations. Alternative approaches to traditional developmental toxicity testing have been proposed in the form of in vitro data (e.g., embryonic stem cells, zebrafish embryos, HTS assays) and in silico models (e.g., computational toxicology). To increase the diversity of assays used to assess developmental toxicity in EPA’s ToxCast program, we tested the chemicals in Stemina’s metabolomics-based platform that utilizes the commecrially available H9 human embryonic stem cell line. The devTOXqP dataset for ToxCast of high-quality based on replicate samples and model performance (82% balanced accuracy, 0.71 sensitivity and 1.00 specificity). To date, 136 ToxCast chemicals (12.8% of 1065 tested) were positive in this platform; 48 triggered the biomarker signal without any change in hESC viability and 88 triggered activity concurrent with effects on cell viability. Work is in progress to complete the STM dataset entry into the TCPL, compare data with results from zFish and mESC platforms, profile bioactivity (ToxCastDB), endpoints (ToxRefDB), chemotypes (DSSTox)

Qualification of a precise and easy-to-handle sweat casting imprint method for the prediction and quantification of anti-perspirant efficacy.

PubMed

Keyhani, R; Scheede, S; Thielecke, I; Wenck, H; Schmucker, R; Schreiner, V; Ennen, J; Herpens, A

2009-06-01

A time- and cost-effective sweat casting method using the forearm as test site to assess the efficacy of several anti-perspirant formulations with a low number of test subjects has been evaluated and qualified. The imprint sweat casting method is based on a 2-component silcone-imprint technique to measure the efficacy of more than eight products in parallel with the same test subject. In studies using aluminum chlorohydrate (ACH) formulations as test anti-perspirants, a clear-cut correlation could be demonstrated between sweat gland activities measured by the imprint method and gravimetric measurement of sweat gland activities. Concentration-dependent inhibition of sweat gland activity could be observed with the imprint technique up to an ACH concentration of 15%, and all formulations containing 2% ACH or above resulted in statistically significant reduction of sweat gland activity (P < 0.001) when compared with untreated control areas. Furthermore, the SDs of individual studies using the imprint technique were in a range of +/-20% of sweat gland activity, which can be regarded rather low for in vivo measurements of a complex process like sweat secretion. A group-wise comparison between the measurements of anti-perspirant activity as determined by the imprint protocol and the Food and Drug Administration (FDA) Guideline compliant gravimetric hot-room protocol revealed that the test results for anti-perspirant activity obtained with the imprint protocol are similar to those obtained with the hot-room protocol. Moreover, the data generated with the imprint protocol have a high predictive value for the outcome of a later guideline-compliant hot-room test. As the imprint casting method tends to be a little more sensitive for formulations with low anti-perspirant activity, and seems to be associated with less interassay variability than the standard gravimetric hot-room test, the imprint casting method may select products which later fail to pass the standard gravimetric hot-room test. Meanwhile the imprint sweat casting has proven to be a robust method useful to support efficacy-oriented product development. Therefore, in later stages of utilization it might even evolve into an efficient claim substantiation tool.

Accuracy and precision of occlusal contacts of stereolithographic casts mounted by digital interocclusal registrations.

PubMed

Krahenbuhl, Jason T; Cho, Seok-Hwan; Irelan, Jon; Bansal, Naveen K

2016-08-01

Little peer-reviewed information is available regarding the accuracy and precision of the occlusal contact reproduction of digitally mounted stereolithographic casts. The purpose of this in vitro study was to evaluate the accuracy and precision of occlusal contacts among stereolithographic casts mounted by digital occlusal registrations. Four complete anatomic dentoforms were arbitrarily mounted on a semi-adjustable articulator in maximal intercuspal position and served as the 4 different simulated patients (SP). A total of 60 digital impressions and digital interocclusal registrations were made with a digital intraoral scanner to fabricate 15 sets of mounted stereolithographic (SLA) definitive casts for each dentoform. After receiving a total of 60 SLA casts, polyvinyl siloxane (PVS) interocclusal records were made for each set. The occlusal contacts for each set of SLA casts were measured by recording the amount of light transmitted through the interocclusal records. To evaluate the accuracy between the SP and their respective SLA casts, the areas of actual contact (AC) and near contact (NC) were calculated. For precision analysis, the coefficient of variation (CoV) was used. The data was analyzed with t tests for accuracy and the McKay and Vangel test for precision (α=.05). The accuracy analysis showed a statistically significant difference between the SP and the SLA cast of each dentoform (P<.05). For the AC in all dentoforms, a significant increase was found in the areas of actual contact of SLA casts compared with the contacts present in the SP (P<.05). Conversely, for the NC in all dentoforms, a significant decrease was found in the occlusal contact areas of the SLA casts compared with the contacts in the SP (P<.05). The precision analysis demonstrated the different CoV values between AC (5.8 to 8.8%) and NC (21.4 to 44.6%) of digitally mounted SLA casts, indicating that the overall precision of the SLA cast was low. For the accuracy evaluation, statistically significant differences were found between the occlusal contacts of all digitally mounted SLA casts groups, with an increase in AC values and a decrease in NC values. For the precision assessment, the CoV values of the AC and NC showed the digitally articulated cast's inability to reproduce the uniform occlusal contacts. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Timing of Getter Material Addition in Cementitious Wasteforms

NASA Astrophysics Data System (ADS)

Lawter, A.; Qafoku, N. P.; Asmussen, M.; Neeway, J.; Smith, G. L.

2015-12-01

A cementitious waste form, Cast Stone, is being evaluated as a possible supplemental immobilization technology for the Hanford sites's low activity waste (LAW), which contains radioactive 99Tc and 129I, as part of the tank waste cleanup mission. Cast Stone is made of a dry blend 47% blast furnace slag, 45% fly ash, and 8% ordinary Portland cement, mixed with a low-activity waste (LAW). To improve the retention of Tc and/or I in Cast Stone, materials with a high affinity for Tc and/or I, termed "getters," can be added to provide a stable domain for the radionuclides of concern. Previous testing conducted with a variety of getters has identified Tin(II)-Apatite and Silver Exchanged Zeolite as promising candidates for Tc and I, respectively. Investigation into the sequence in which getters are added to Cast Stone was performed following two methods: 1) adding getters to the Cast Stone dry blend, and then mixing with liquid waste, and 2) adding getters to the liquid waste first, followed by addition of the Cast Stone dry blend. Cast Stone monolith samples were prepared with each method and leach tests, following EPA method 1315, were conducted in either distilled water or simulated vadose zone porewater for a period of up to 63 days. The leachate was analyzed for Tc, I, Na, NO3-, NO2- and Cr with ICP-MS, ICP-OES and ion chromatography and the results indicated that the Cast Stone with getter addition in the dry blend mix (method 1) has lower rates of Tc and I leaching. The mechanisms of radionuclide release from the Cast Stone were also investigated with a variety of solid phase characterization techniques of the monoliths before and after leaching, such as XRD, SEM/EDS, TEM/SAED and other spectroscopic techniques.

Evaluation of Mechanical Properties and Marginal Fit of Crowns Fabricated Using Commercially Pure Titanium and FUS-Invest

PubMed Central

Wu, Jinshuang; Wang, Xianli; Xing, Helin; Guo, Tianwen; Dong, Chaofang

2017-01-01

This study investigated the mechanical properties and single crown accuracy of the tailor-made Fourth University Stomatology investment (FUS-invest) for casting titanium. Background. Current investment for casting titanium is not optimal for obtaining high-quality castings, and the commercially available titanium investment is costly. Methods. Titanium specimens were cast using the tailor-made FUS-invest. The mechanical properties were tested using a universal testing machine. Fractured castings were characterized by energy-dispersive spectroscopy. 19 titanium crowns were produced using FUS-invest and another 19 by Symbion. The accuracy of crowns was evaluated. Results. The mechanical properties of the titanium cast by FUS-invest were elastic modulus 125.6 ± 8.8 GPa, yield strength 567.5 ± 11.1 MPa, tensile strength 671.2 ± 15.6 MPa, and elongation 4.6 ± 0.2%. For marginal fit, no significant difference (P > 0.05) was found at four marker points of each group. For internal fit, no significant difference (P > 0.05) was found between two groups, whereas significant difference (P < 0.01) was found at different mark point of each group. Conclusions. The mechanical properties of titanium casted using FUS-invest fulfilled the ISO 9693 criteria. The marginal and internal fit of the titanium crowns using either the FUS-invest or Symbion were similar. PMID:28913355

Effect of Thermal and Chemical Treatment on the Microstructural, Mechanical and Machining Performance of W319 Al-Si-Cu Cast Alloy Engine Blocks and Directionally Solidified Machinability Test Blocks

NASA Astrophysics Data System (ADS)

Szablewski, Daniel

The research presented in this work is focused on making a link between casting microstructural, mechanical and machining properties for 319 Al-Si sand cast components. In order to achieve this, a unique Machinability Test Block (MTB) is designed to simulate the Nemak V6 Al-Si engine block solidification behavior. This MTB is then utilized to cast structures with in-situ nano-alumina particle master alloy additions that are Mg based, as well as independent in-situ Mg additions, and Sr additions to the MTB. The Universal Metallurgical Simulator and Analyzer (UMSA) Technology Platform is utilized for characterization of each cast structure at different Secondary Dendrite Arm Spacing (SDAS) levels. The rapid quench method and Jominy testing is used to assess the capability of the nano-alumina master alloy to modify the microstructure at different SDAS levels. Mechanical property assessment of the MTB is done at different SDAS levels on cast structures with master alloy additions described above. Weibull and Quality Index statistical analysis tools are then utilized to assess the mechanical properties. The MTB is also used to study single pass high speed face milling and bi-metallic cutting operations where the Al-Si hypoeutectic structure is combined with hypereutectoid Al-Si liners and cast iron cylinder liners. These studies are utilized to aid the implementation of Al-Si liners into the Nemak V6 engine block and bi-metallic cutting of the head decks. Machining behavior is also quantified for the investigated microstructures, and the Silicon Modification Level (SiML) is utilized for microstructural analysis as it relates to the machining behavior.

Environmental Impact on Vascular Development Predicted by High-Throughput Screening

PubMed Central

Judson, Richard S.; Reif, David M.; Sipes, Nisha S.; Singh, Amar V.; Chandler, Kelly J.; DeWoskin, Rob; Dix, David J.; Kavlock, Robert J.; Knudsen, Thomas B.

2011-01-01

Background: Understanding health risks to embryonic development from exposure to environmental chemicals is a significant challenge given the diverse chemical landscape and paucity of data for most of these compounds. High-throughput screening (HTS) in the U.S. Environmental Protection Agency (EPA) ToxCast™ project provides vast data on an expanding chemical library currently consisting of > 1,000 unique compounds across > 500 in vitro assays in phase I (complete) and Phase II (under way). This public data set can be used to evaluate concentration-dependent effects on many diverse biological targets and build predictive models of prototypical toxicity pathways that can aid decision making for assessments of human developmental health and disease. Objective: We mined the ToxCast phase I data set to identify signatures for potential chemical disruption of blood vessel formation and remodeling. Methods: ToxCast phase I screened 309 chemicals using 467 HTS assays across nine assay technology platforms. The assays measured direct interactions between chemicals and molecular targets (receptors, enzymes), as well as downstream effects on reporter gene activity or cellular consequences. We ranked the chemicals according to individual vascular bioactivity score and visualized the ranking using ToxPi (Toxicological Priority Index) profiles. Results: Targets in inflammatory chemokine signaling, the vascular endothelial growth factor pathway, and the plasminogen-activating system were strongly perturbed by some chemicals, and we found positive correlations with developmental effects from the U.S. EPA ToxRefDB (Toxicological Reference Database) in vivo database containing prenatal rat and rabbit guideline studies. We observed distinctly different correlative patterns for chemicals with effects in rabbits versus rats, despite derivation of in vitro signatures based on human cells and cell-free biochemical targets, implying conservation but potentially differential contributions of developmental pathways among species. Follow-up analysis with antiangiogenic thalidomide analogs and additional in vitro vascular targets showed in vitro activity consistent with the most active environmental chemicals tested here. Conclusions: We predicted that blood vessel development is a target for environmental chemicals acting as putative vascular disruptor compounds (pVDCs) and identified potential species differences in sensitive vascular developmental pathways. PMID:21788198

Digital versus conventional implant impressions for edentulous patients: accuracy outcomes.

PubMed

Papaspyridakos, Panos; Gallucci, German O; Chen, Chun-Jung; Hanssen, Stijn; Naert, Ignace; Vandenberghe, Bart

2016-04-01

To compare the accuracy of digital and conventional impression techniques for completely edentulous patients and to determine the effect of different variables on the accuracy outcomes. A stone cast of an edentulous mandible with five implants was fabricated to serve as master cast (control) for both implant- and abutment-level impressions. Digital impressions (n = 10) were taken with an intraoral optical scanner (TRIOS, 3shape, Denmark) after connecting polymer scan bodies. For the conventional polyether impressions of the master cast, a splinted and a non-splinted technique were used for implant-level and abutment-level impressions (4 cast groups, n = 10 each). Master casts and conventional impression casts were digitized with an extraoral high-resolution scanner (IScan D103i, Imetric, Courgenay, Switzerland) to obtain digital volumes. Standard tessellation language (STL) datasets from the five groups of digital and conventional impressions were superimposed with the STL dataset from the master cast to assess the 3D (global) deviations. To compare the master cast with digital and conventional impressions at the implant level, analysis of variance (ANOVA) and Scheffe's post hoc test was used, while Wilcoxon's rank-sum test was used for testing the difference between abutment-level conventional impressions. Significant 3D deviations (P < 0.001) were found between Group II (non-splinted, implant level) and control. No significant differences were found between Groups I (splinted, implant level), III (digital, implant level), IV (splinted, abutment level), and V (non-splinted, abutment level) compared with the control. Implant angulation up to 15° did not affect the 3D accuracy of implant impressions (P > 0.001). Digital implant impressions are as accurate as conventional implant impressions. The splinted, implant-level impression technique is more accurate than the non-splinted one for completely edentulous patients, whereas there was no difference in the accuracy at the abutment level. The implant angulation up to 15° did not affect the accuracy of implant impressions. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Mechanical Properties and Tensile Failure Analysis of Novel Bio-absorbable Mg-Zn-Cu and Mg-Zn-Se Alloys for Endovascular Applications

PubMed Central

Persaud-Sharma, Dharam; Budiansky, Noah; McGoron, Anthony J.

2013-01-01

In this paper, the mechanical properties and tensile failure mechanism of two novel bio-absorbable as-cast Mg-Zn-Se and Mg-Zn-Cu alloys for endovascular medical applications are characterized. Alloys were manufactured using an ARC melting process and tested as-cast with compositions of Mg-Zn-Se and Mg-Zn-Cu, being 98/1/1 wt.% respectively. Nanoindentation testing conducted at room temperature was used to characterize the elastic modulus (E) and surface hardness (H) for both the bare alloys and the air formed oxide layer. As compared to currently available shape memory alloys and degradable as-cast alloys, these experimental alloys possess superior as-cast mechanical properties that can increase their biocompatibility, degradation kinetics, and the potential for medical device creation. PMID:23543822

The effects of different types of investments on the alpha-case layer of titanium castings.

PubMed

Guilin, Yu; Nan, Li; Yousheng, Li; Yining, Wang

2007-03-01

Different types of investments affect the formation of the alpha-case (alpha-case) layer on titanium castings. This alpha-case layer may possibly alter the mechanical properties of cast titanium, which may influence the fabrication of removable and fixed prostheses. The formation mechanism for the alpha-case layer is not clear. The aim of this study was to evaluate the effect of 3 types of investments on the microstructure, composition, and microhardness of the alpha-case layer on titanium castings. Fifteen wax columns with a diameter of 5 mm and a length of 40 mm were divided into 3 groups of 5 patterns each. Patterns were invested using 3 types of investment materials, respectively, and were cast in pure titanium. The 3 types of materials tested were SiO(2)-, Al(2)O(3)-, and MgO-based investments. All specimens were sectioned and prepared for metallographic observation. The microstructure and composition of the surface reaction layer of titanium castings were investigated by scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The surface microhardness (VHN) for all specimens was measured using a hardness testing machine, and a mean value for each group was calculated. The alpha-case layer on titanium castings invested with SiO(2)-, Al(2)O(3)-, and MgO-based investments consisted of 3 layers-namely, the oxide layer, alloy layer, and hardening layer. In this study, the oxide layer and alloy layer were called the reaction layer. The thickness of the reaction layer for titanium castings using SiO(2)-, Al(2)O(3)-, and MgO-based investments was approximately 80 microm, 50 microm, and 14 microm, respectively. The surface microhardness of titanium castings made with SiO(2)-based investments was the highest, and that with MgO-based investments was the lowest. The type of investment affects the microstructure and microhardness of the alpha-case layer of titanium castings. Based on the thickness of the surface reaction layer and the surface microhardness of titanium castings, MgO-based investment materials may be the best choice for casting these materials.

Screening the ToxCast Phase 1, 2, and e1k Chemical Libraries for Inhibition of Deiodinase Type 1, 2 and 3 Enzyme Activity

EPA Science Inventory

Thyroid hormone (TH) homeostasis is dependent on multiple proteins for TH synthesis, transport, and peripheral metabolism and elimination. Deiodinase enzymes play an essential role in converting THs between active and inactive forms by converting the pro-hormone thyroxine (T4) to...

DEVELOPMENT OF AN IN VITRO RADIOACTIVE IODIDE UPTAKE ASSAY (RAIU) WITH HUMAN NIS-EXPRESSING HEK293T-EPA CELL LINE

EPA Science Inventory

Many high-throughput screening (HTPS) assays are available in the US EPA ToxCast program for estrogen and androgen pathways; only a limited number of assays exist for thyroid pathways. One potential target of thyroid-disrupting chemicals is the active uptake of iodide into the t...

Screening the ToxCast Phase 1, 2, and e1k chemical libraries for inhibition of Deiodinase Types 1, 2 and 3 enzyme activity

EPA Science Inventory

Thyroid hormone (TH) homeostasis is dependent on multiple proteins for TH synthesis, transport, and peripheral metabolism and elimination. Deiodinase enzymes play an essential role in converting THs between active and inactive forms by deiodinating the pro-hormone thyroxine (T4) ...

Comparison and Analysis of Toxcast Data with In Vivo Data for Food-Relevant Compounds Using The Risk21 Approach

EPA Science Inventory

The ToxCast program has generated a great wealth of in vitro high throughput screening (HTS) data on a large number of compounds, providing a unique resource of information on the bioactivity of these compounds. However, analysis of these data are ongoing, and interpretation and ...

The reliability and validity of measurements of human dental casts made by an intra-oral 3D scanner, with conventional hand-held digital callipers as the comparison measure.

PubMed

Rajshekar, Mithun; Julian, Roberta; Williams, Anne-Marie; Tennant, Marc; Forrest, Alex; Walsh, Laurence J; Wilson, Gary; Blizzard, Leigh

2017-09-01

Intra-oral 3D scanning of dentitions has the potential to provide a fast, accurate and non-invasive method of recording dental information. The aim of this study was to assess the reliability of measurements of human dental casts made using a portable intra-oral 3D scanner appropriate for field use. Two examiners each measured 84 tooth and 26 arch features of 50 sets of upper and lower human dental casts using digital hand-held callipers, and secondly using the measuring tool provided with the Zfx IntraScan intraoral 3D scanner applied to the virtual dental casts. The measurements were repeated at least one week later. Reliability and validity were quantified concurrently by calculation of intra-class correlation coefficients (ICC) and standard errors of measurement (SEM). The measurements of the 110 landmark features of human dental casts made using the intra-oral 3D scanner were virtually indistinguishable from measurements of the same features made using conventional hand-held callipers. The difference of means as a percentage of the average of the measurements by each method ranged between 0.030% and 1.134%. The intermethod SEMs ranged between 0.037% and 0.535%, and the inter-method ICCs ranged between 0.904 and 0.999, for both the upper and the lower arches. The inter-rater SEMs were one-half and the intra-method/rater SEMs were one-third of the inter-method values. This study demonstrates that the Zfx IntraScan intra-oral 3D scanner with its virtual on-screen measuring tool is a reliable and valid method for measuring the key features of dental casts. Copyright © 2017 Elsevier B.V. All rights reserved.

Dimensional control of die castings

NASA Astrophysics Data System (ADS)

Karve, Aniruddha Ajit

The demand for net shape die castings, which require little or no machining, is steadily increasing. Stringent customer requirements are forcing die casters to deliver high quality castings in increasingly short lead times. Dimensional conformance to customer specifications is an inherent part of die casting quality. The dimensional attributes of a die casting are essentially dependent upon many factors--the quality of the die and the degree of control over the process variables being the two major sources of dimensional error in die castings. This study focused on investigating the nature and the causes of dimensional error in die castings. The two major components of dimensional error i.e., dimensional variability and die allowance were studied. The major effort of this study was to qualitatively and quantitatively study the effects of casting geometry and process variables on die casting dimensional variability and die allowance. This was accomplished by detailed dimensional data collection at production die casting sites. Robust feature characterization schemes were developed to describe complex casting geometry in quantitative terms. Empirical modeling was utilized to quantify the effects of the casting variables on dimensional variability and die allowance for die casting features. A number of casting geometry and process variables were found to affect dimensional variability in die castings. The dimensional variability was evaluated by comparisons with current published dimensional tolerance standards. The casting geometry was found to play a significant role in influencing the die allowance of the features measured. The predictive models developed for dimensional variability and die allowance were evaluated to test their effectiveness. Finally, the relative impact of all the components of dimensional error in die castings was put into perspective, and general guidelines for effective dimensional control in the die casting plant were laid out. The results of this study will contribute to enhancement of dimensional quality and lead time compression in the die casting industry, thus making it competitive with other net shape manufacturing processes.

Seal Integrity of Selected Fuzes as Measured by Three Leak Test Methods

DTIC Science & Technology

1976-09-01

the worst fuze from the seal standpoint. The M503A-2 fuze body is made from a cast aluminum alloy . The casting process leaves voids which, after...leak resistance of the joint. WDU4A/A The design of this fuze depends upon ultrasonic welding to seal lid to case. The specified leak test merely...test is probably one of the better leakage tests from an effectiveness standpoint. However, from lot quantities of 690 and 480, reject rates of 20% were

Inter-Individual Variability in High-Throughput Risk ...

EPA Pesticide Factsheets

We incorporate realistic human variability into an open-source high-throughput (HT) toxicokinetics (TK) modeling framework for use in a next-generation risk prioritization approach. Risk prioritization involves rapid triage of thousands of environmental chemicals, most which have little or no existing TK data. Chemicals are prioritized based on model estimates of hazard and exposure, to decide which chemicals should be first in line for further study. Hazard may be estimated with in vitro HT screening assays, e.g., U.S. EPA’s ToxCast program. Bioactive ToxCast concentrations can be extrapolated to doses that produce equivalent concentrations in body tissues using a reverse TK approach in which generic TK models are parameterized with 1) chemical-specific parameters derived from in vitro measurements and predicted from chemical structure; and 2) with physiological parameters for a virtual population. Here we draw physiological parameters from realistic estimates of distributions of demographic and anthropometric quantities in the modern U.S. population, based on the most recent CDC NHANES data. A Monte Carlo approach, accounting for the correlation structure in physiological parameters, is used to estimate ToxCast equivalent doses for the most sensitive portion of the population. To quantify risk, ToxCast equivalent doses are compared to estimates of exposure rates based on Bayesian inferences drawn from NHANES urinary analyte biomonitoring data. The inclusion

Transtibial Prosthetic Socket Shape in a Developing Country: A study to compare initial outcomes in Pressure Cast hydrostatic and Patella Tendon Bearing designs.

PubMed

Laing, Sheridan; Lythgo, Noel; Lavranos, Jim; Lee, Peter Vee Sin

2017-10-01

This study compared the physical function and comfort level of patients with unilateral transtibial amputation after being fitted with a hand-cast Patella Tendon Bearing (PTB) socket and a pressure-cast (PCAST) hydrocast socket. The latter technique aims to reduce the skill dependency currently required for socket manufacture and fit. The study was conducted at the Vietnamese Training Centre for Orthopaedic Technologies and involved seventeen Vietnamese participants with unilateral transtibial amputation, all of whom were long term users of prosthetics. All participants were fitted with two sockets manufactured using both hand-cast and PCAST techniques with International Committee of the Red Cross components. Walking tests (timed up and go test and six-minute-walk-test), spatio-temporal gait analyses and subjective comfort assessments were completed after a short acclimatisation period with each socket. The participant-preferred socket was also noted. No significant differences were found for the measures of mobility, functional capacity, spatio-temporal gait parameters, gait symmetry, perceived comfort or participant socket preference. The results show the initial patient outcomes are similar when participants are fitted with a hand-cast PTB socket and a PCAST hydrocast sockets. Future work should confirm these findings in a longer trial. Copyright © 2017 Elsevier B.V. All rights reserved.

Molding of strength testing samples using modern PDCPD material for purpose of automotive industry

NASA Astrophysics Data System (ADS)

Grabowski, L.; Baier, A.; Sobek, M.

2017-08-01

The casting of metal materials is widely known but the molding of composite polymer materials is not well-known method still. The initial choice of method for producing composite bodies was the method of casting of PDCPD material. For purpose of performing casting of polymer composite material, a special mold was made. Firstly, the 3D printed, using PLA material, mold was used. After several attempts of casting PDCPD many problems were encountered. The second step was to use mold milled from a firm and dense isocyanate foam. After several attempts research shown that this solution is more resistant to high-temperature peak, but this material is too fragile to use it several times. This solution also prevents mold from using external heating, which can be necessary for performing correct molding process. The last process was to use the aluminum mold, which is dedicated to PDCPD polymer composite, because of low adhesiveness. This solution leads to perform correct PDCPD polymer composite material injection. After performing casting operation every PDCPD testing samples were tested. These results were compared together. The result of performed work was to archive correct properties of injection of composite material. Research and results were described in detail in this paper.

Vacuum investment cast PH13-8Mo corrosion resistant steel. (SAE standard)

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1991-07-01

An industry-wide interest has arisen with regards to the properties and capabilities of investment cast PH 13-8Mo corrosion resistant steel. Specifically of interest are the structural applications in the aerospace industry for this product heat treated to the H1000 condition. The objective of this AMEC cooperative test program was to generate and compile useful data for aerospace structural evaluation of investment cast PH 13-8Mo heat treated to H1000. The determination was made of overall mechanical properties, fatigue, fracture toughness, and crack growth data along with basic microstructural evaluation of the investment cast material. The evaluation of mechanical property variations betweenmore » cast and machined tensile specimens and evaluation of microstructural constituents. PH 13-8Mo, H1000 investment castings for use in the aerospace industry is included.« less

Fit of cast commercially pure titanium and Ti-6Al-4V alloy crowns before and after marginal refinement by electrical discharge machining.

PubMed

Contreras, Edwin Fernando Ruiz; Henriques, Guilherme Elias Pessanha; Giolo, Suely Ruiz; Nobilo, Mauro Antonio Arruda

2002-11-01

Titanium has been suggested as a replacement for alloys currently used in single-tooth restorations and fixed partial dentures. However, difficulties in casting have resulted in incomplete margins and discrepancies in marginal fit. This study evaluated and compared the marginal fit of crowns fabricated from a commercially pure titanium (CP Ti) and from Ti-6Al-4V alloy with crowns fabricated from a Pd-Ag alloy that served as a control. Evaluations were performed before and after marginal refinement by electrical discharge machining (EDM). Forty-five bovine teeth were prepared to receive complete cast crowns. Stone and copper-plated dies were obtained from impressions. Fifteen crowns were cast with each alloy (CP Ti, Ti-6Al-4V, and Pd-Ag). Marginal fit measurements (in micrometers) were recorded at 4 reference points on each casting with a traveling microscope. Marginal refinement with EDM was conducted on the titanium-based crowns, and measurements were repeated. Data were analyzed with the Kruskal-Wallis test, paired t test, and independent t test at a 1% probability level. The Kruskal-Wallis test showed significant differences among mean values of marginal fit for the as-cast CP Ti crowns (mean [SD], 83.9 [26.1] microm) and the other groups: Ti-6Al-4V (50.8 [17.2] microm) and Pd-Ag (45.2 [10.4] microm). After EDM marginal refinement, significant differences were detected among the Ti-6Al-4V crowns (24.5 [10.9] microm) and the other 2 groups: CP Ti (50.6 [20.0] microm) and Pd-Ag (not modified by EDM). Paired t test results indicated that marginal refinement with EDM effectively improved the fit of CP Ti crowns (from 83.9 to 50.6 microm) and Ti-6Al-4V crowns (from 50.8 to 24.5 microm). However, the difference in improvement between the two groups was not significant by t test. Within the limitations of this study, despite the superior results for Ti-6Al-4V, both groups of titanium-based crowns had clinically acceptable marginal fits. After EDM marginal refinement, the fit of cast CP Ti and Ti-6Al-4V crowns improved significantly.

Driving with a short arm cast in a simulator.

PubMed

Mansour, Damian; Mansour, Kristin Gotaas; Kenny, Benjamin William; Attia, John; Meads, Bryce

2015-12-01

To test the ability to steer in a driving simulator in subjects with a short arm cast. 17 men and 13 women aged 23 to 67 (mean, 37) years who had a valid driver's licence were randomised to the cast-first group (n=16; 7 had the cast on the dominant arm) or the cast-second group (n=14; 8 had the cast on the dominant arm) and drove in a simulator. A short arm plaster-of-Paris cast was applied in a neutral position, allowing free movement of the metacarpophalangeal joints, thumb, and elbow joint. Outcome measures included the number of driving off track instances, the number of crashes, the lap time, and the effect of hand dominance on these parameters. Subjects were asked whether the cast had impeded their steering ability. Subjects with or without a cast were comparable in terms of the number of driving off track instances, number of crashes, and lap time. Compared with no cast, the odds ratio (OR) of a subject in a cast driving off the track was 1.02 (p=0.921) and having a crash was 0.79 (p=0.047). All subjects were 1.23 times more likely to drive off the track in their first lap (OR=2.66, p=0.019). The mean lap time decreased for each consecutive lap from the 2nd to 5th laps. Subjects driving with a cast on the dominant or non-dominant arm were comparable. 26 out of the 30 participants considered that the plaster cast impeded their steering ability. Compared with no cast, driving with a short arm cast did not significantly decrease steering ability in a driving simulator.

Accuracy of single-abutment digital cast obtained using intraoral and cast scanners.

PubMed

Lee, Jae-Jun; Jeong, Ii-Do; Park, Jin-Young; Jeon, Jin-Hun; Kim, Ji-Hwan; Kim, Woong-Chul

2017-02-01

Scanners are frequently used in the fabrication of dental prostheses. However, the accuracy of these scanners is variable, and little information is available. The purpose of this in vitro study was to compare the accuracy of cast scanners with that of intraoral scanners by using different image impression techniques. A poly(methyl methacrylate) master model was fabricated to replicate a maxillary first molar single-abutment tooth model. The master model was scanned with an accurate engineering scanner to obtain a true value (n=1) and with 2 intraoral scanners (CEREC Bluecam and CEREC Omnicam; n=6 each). The cast scanner scanned the master model and duplicated the dental stone cast from the master model (n=6). The trueness and precision of the data were measured using a 3-dimensional analysis program. The Kruskal-Wallis test was used to compare the different sets of scanning data, followed by a post hoc Mann-Whitney U test with a significance level modified by Bonferroni correction (α/6=.0083). The type 1 error level (α) was set at .05. The trueness value (root mean square: mean ±standard deviation) was 17.5 ±1.8 μm for the Bluecam, 13.8 ±1.4 μm for the Omnicam, 17.4 ±1.7 μm for cast scanner 1, and 12.3 ±0.1 μm for cast scanner 2. The differences between the Bluecam and the cast scanner 1 and between the Omnicam and the cast scanner 2 were not statistically significant (P>.0083), but a statistically significant difference was found between all the other pairs (P<.0083). The precision of the scanners was 12.7 ±2.6 μm for the Bluecam, 12.5 ±3.7 μm for the Omnicam, 9.2 ±1.2 μm for cast scanner 1, and 6.9 ±2.6 μm for cast scanner 2. The differences between Bluecam and Omnicam and between Omnicam and cast scanner 1 were not statistically significant (P>.0083), but there was a statistically significant difference between all the other pairs (P<.0083). An Omnicam in video image impression had better trueness than a cast scanner but with a similar level of precision. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Properties of a hybrid plaster-fibreglass cast

PubMed Central

Charles, Mark N.; Yen, David

2000-01-01

Objective To examine the suitability of a plaster-fibreglass hybrid cast for orthopedic applications, comparing them to plaster of Paris (POP) and fibreglass constructs. Method Groups of 10 standardized hybrid, POP and fibreglass casts were studied. An Instron servo-hydraulic system was used to test the casts in 3-point bending and shear. Outcome measures Strength, stiffness, weight, thickness and cost of the 3 types of cast, and shear strength at the interface between the POP and fibreglass in the hybrid casts. Results The hybrid casts were twice as strong as the POP constructs, were stiffer and weighed 14% less but were thicker and cost 2.5 times more. They were almost as strong as and less than half the cost of the fibreglass constructs but were thicker, not as stiff, and weighed 42% more. The shear strength of the POP–fibreglass interface in the hybrid casts was higher than the 3-point bending strength of this construct by a factor of 3. Conclusions Plaster-fibreglass hybrid casts should be considered for orthopedic use on the basis of their strength, stiffness, weight and cost, combined with their acknowledged advantages of good moulding ability and water resistance. PMID:11045095

Short-term after-effect of forearm cast removal in children.

PubMed

Katz, Kalman; Weigl, Daniel; Becker, Tal; Attias, Joseph; Bar-On, Elhanan

2011-05-01

To investigate the sensation in the hand after forearm cast removal in children. The study group included 33 consecutive children who were treated nonoperatively for a forearm fracture at our center over a 1-year period. The children were asked to report any sensation in the ipsilateral hand after cast removal, and the findings were analyzed against background and fracture-related data. The patients ranged in age from 6 to 14 years (median 10.00 years). Seventeen had been immobilized in an above-elbow cast and the remainder in a below-elbow cast. All children treated with an above-elbow cast complained that after cast removal, the hand on that side felt limp, and they had to hold it with the contralateral hand. By contrast, only one child treated with a below-elbow cast reported this sensation (p = 0.0001, Fisher exact test). Orthopedic surgeons and rehabilitation unit staff should be aware of the possibility of a very short-term sensation of drooping and weakness of the hand after removal of an above-elbow cast in children and prepare the child and parents accordingly in order to lessen unnecessary anxiety.

Evaluation of marginal gap of Ni-Cr copings made with conventional and accelerated casting techniques.

PubMed

Tannamala, Pavan Kumar; Azhagarasan, Nagarasampatti Sivaprakasam; Shankar, K Chitra

2013-01-01

Conventional casting techniques following the manufacturers' recommendations are time consuming. Accelerated casting techniques have been reported, but their accuracy with base metal alloys has not been adequately studied. We measured the vertical marginal gap of nickel-chromium copings made by conventional and accelerated casting techniques and determined the clinical acceptability of the cast copings in this study. Experimental design, in vitro study, lab settings. Ten copings each were cast by conventional and accelerated casting techniques. All copings were identical, only their mold preparation schedules differed. Microscopic measurements were recorded at ×80 magnification on the perpendicular to the axial wall at four predetermined sites. The marginal gap values were evaluated by paired t test. The mean marginal gap by conventional technique (34.02 μm) is approximately 10 μm lesser than that of accelerated casting technique (44.62 μm). As the P value is less than 0.0001, there is highly significant difference between the two techniques with regard to vertical marginal gap. The accelerated casting technique is time saving and the marginal gap measured was within the clinically acceptable limits and could be an alternative to time-consuming conventional techniques.

Rough case-based reasoning system for continues casting

NASA Astrophysics Data System (ADS)

Su, Wenbin; Lei, Zhufeng

2018-04-01

The continuous casting occupies a pivotal position in the iron and steel industry. The rough set theory and the CBR (case based reasoning, CBR) were combined in the research and implementation for the quality assurance of continuous casting billet to improve the efficiency and accuracy in determining the processing parameters. According to the continuous casting case, the object-oriented method was applied to express the continuous casting cases. The weights of the attributes were calculated by the algorithm which was based on the rough set theory and the retrieval mechanism for the continuous casting cases was designed. Some cases were adopted to test the retrieval mechanism, by analyzing the results, the law of the influence of the retrieval attributes on determining the processing parameters was revealed. A comprehensive evaluation model was established by using the attribute recognition theory. According to the features of the defects, different methods were adopted to describe the quality condition of the continuous casting billet. By using the system, the knowledge was not only inherited but also applied to adjust the processing parameters through the case based reasoning method as to assure the quality of the continuous casting and improve the intelligent level of the continuous casting.

Glovebox Advanced Casting System Casting Optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fielding, Randall Sidney

2016-03-01

Casting optimization in the GACS included three broad areas; casting of U-10Zr pins, incorporation of an integral FCCI barrier, and development of a permanent crucible coating. U-10Zr casting was improved over last year’s results by modifying the crucible design to minimize contact with the colder mold. Through these modifications casting of a three pin batch was successful. Incorporation of an integral FCCI barrier also was optimized through furnace chamber pressure changes during the casting cycle to reduce gas pressures in the mold cavities which led to three full length pins being cast which incorporated FCCI barriers of three different thicknesses.more » Permanent crucible coatings were tested against a base case; 1500°C for 10 minutes in a U-20Pu-10Zr molten alloy. None of the candidate coating materials showed evidence of failure upon initial visual examination. In all areas of work a large amount of characterization will be needed to fully determine the effects of the optimization activities. The characterization activities and future work will occur next year.« less

Properties of experimental titanium cast investment mixing with water reducing agent solution.

PubMed

Zhang, Zutai; Ding, Ning; Tamaki, Yukimichi; Hotta, Yasuhiro; Han-Cheol, Cho; Miyazaki, Takashi

2012-01-01

This study aimed to develop a dental investment for titanium casting. ZrO(2) and Al(2)O(3) were selected as refractory materials to prepare three investments (Codes: A-C) according to the quantity of Zr. Al(2)O(3) cement was used as a binder at a ratio of 15%, they were mixed with special mixing liquid. B1 was used as a control mixed with water. Fundamental examinations were statistically evaluated. A casting test was performed with investment B. Fluidities, setting times, and green strengths showed no remarkable differences; however, they were significantly different from those of B1. Expansion values for A, B, C, and B1 at 850°C were 1.03%±0.08%, 1.96%±0.17%, 4.35%±0.23%, and 1.50%±0.28%, respectively. Castings were covered by only small amounts of mold materials. The hardness test showed no significant differences between castings from B and the ones from commercial investments. The experimental special mixing liquid effectively reduced the water/powder ratio and improved the strength and thermal expansion.

Constitutive behavior of as-cast AA1050, AA3104, and AA5182

NASA Astrophysics Data System (ADS)

van Haaften, W. M.; Magnin, B.; Kool, W. H.; Katgerman, L.

2002-07-01

Recent thermomechanical modeling to calculate the stress field in industrially direct-chill (DC) cast-aluminum slabs has been successful, but lack of material data limits the accuracy of these calculations. Therefore, the constitutive behavior of three aluminum alloys (AA1050, AA3104, and AA5182) was determined in the as-cast condition using tensile tests at low strain rates and from room temperature to solidus temperature. The parameters of two constitutive equations, the extended Ludwik equation and a combination of the Sellars-Tegart equation with a hardening law, were determined. In order to study the effect of recovery, the constitutive behavior after prestraining at higher temperatures was also investigated. To evaluate the quantified constitutive equations, tensile tests were performed simulating the deformation and cooling history experienced by the material during casting. It is concluded that both constitutive equations perform well, but the combined hardening-Sellars-Tegart (HST) equation has temperature-independent parameters, which makes it easier to implement in a DC casting model. Further, the deformation history of the ingot should be taken into account for accurate stress calculations.

Modeling the surface contamination of dental titanium investment castings.

PubMed

Atwood, R C; Lee, P D; Curtis, R V

2005-02-01

The objective of this study was to develop a computational tool for assisting the design of titanium dental castings with minimal defects and to compare computational simulations with casting experiments. Modeling. An in-house cellular-automata solidification and finite-difference diffusion program was coupled with a commercial casting program and applied to (a) simple geometric wedge models and (b) a 3D-laser scan of a molar crown casting. Experimental. Wedges and molar crowns were hand-waxed and investment cast in commercial purity grade 1 (CP-1) titanium by a commercial dental laboratory. The castings were sectioned and analyzed using light and scanning electron microscopy, X-ray microanalysis, and microhardness testing. In the wedge sample, contamination with impurities (Al, Si), including intermetallic precipitates, was found to extend to a depth ranging from 30 to 120 microm depending on the section thickness and hence the local cooling rate. Microstructural and mechanical (hardness) effects were found to a depth ranging from 80 to 250 microm. The coupled micro/macro model predictions showed reasonable agreement for the pattern of contamination. Dental and medical applications demand close dimensional tolerance and freedom from surface impurities and structural flaws in castings having unique shapes. The ability to predict the structural, mechanical, and chemical changes resulting from the casting process will help to design the casting and post-casting processes to minimize these problems.

Mission Critical STEM Partnership with the Air Force Office of Scientific Research

DTIC Science & Technology

2015-04-06

Dr. Valerie Lundy-Wagner, Senior Research Associate, Community College Research Center Teachers College, Columbia University 29...composites. We were comparing our experiments vs. structural steel . Our project consisted of a 4x4 in square caste. The caste was fabricated by bonding...aluminum and stainless steel . The caste experiments varied from 3, 5, and 7 stainless steel rods embedded in the piece. We tested for tensile strength

Radiographic inspection of porosity in pure titanium dumbbell castings.

PubMed

Nuñez, Juliana Maria Costa; Takahashi, Jessica Mie Ferreira Koyama; Henriques, Guilherme Elias Pessanha; Nóbilo, Mauro Antônio de Arruda; Consani, Rafael Leonardo Xediek; Mesquita, Marcelo Ferraz

2011-09-01

  Titanium frameworks are frequently indicated for implant supported prostheses; however, voids are usually encountered inside cast titanium.   This study aimed to confirm the efficacy of a radiographic technique for inspection of porosity in commercially pure titanium castings with different diameter.   Sixty dumbbell rods (n=20) with a central 1.5, 2.0 and 3.5mm diameter were prepared by lost-wax casting. Cast specimens were finished and polished and submitted to radiographic examination (90kV, 15mA, 0.6s and 10-13mm of distance) using periapical film. The radiographs were visually analysed for the presence of porosity in the extension of the dumbbell or in the central portion of the rods. Data were submitted to Pearson Chi-square test (5%).   The tested radiographic method proved to be suitable for the evaluation of cast frameworks. Internal porosities were observed in most of the specimens (91.7%) (p=0.0005); however, only 20% occurred on the central portion of the rods (p=0.612).   Internal porosities can be visualised through radiographs and occur mostly in small diameter structures. The radiographic evaluation of metal structures can improve the quality of frameworks and thereby potentially increase the longevity of the rehabilitation. © 2010 The Gerodontology Society and John Wiley & Sons A/S.

Maltodextrin Acceptance and Preference in Eight Mouse Strains.

PubMed

Poole, Rachel L; Aleman, Tiffany R; Ellis, Hillary T; Tordoff, Michael G

2016-01-01

Rodents are strongly attracted to the taste(s) of maltodextrins. A first step toward discovery of the underlying genes involves identifying phenotypic differences among inbred strains of mice. To do this, we used 5-s brief-access tests and 48-h 2-bottle choice tests to survey the avidity for the maltodextrin, Maltrin M040, of mice from 8 inbred strains (129S1/SvImJ, A/J, CAST/EiJ, C57BL/6J, NOD/ShiLTJ, NZO/HlLtJ, PWK/PhJ, and WSB/EiJ). In brief-access tests, the CAST and PWK strains licked significantly less maltodextrin than equivalent concentrations of sucrose, whereas the other strains generally licked the 2 carbohydrates equally. Similarly, in 2-bottle choice tests, the CAST and PWK strains drank less 4% maltodextrin than 4% sucrose, whereas the other strains had similar intakes of these 2 solutions; the CAST and PWK strains did not differ from the C57, NOD, or NZO strains in 4% sucrose intake. In sum, we have identified strain variation in maltodextrin perception that is distinct from variation in sucrose perception. The phenotypic variation characterized here will aid in identifying genes responsible for maltodextrin acceptance. Our results identify C57 × PWK mice or NZO × CAST mice as informative crosses to produce segregating hybrids that will expose quantitative trait loci underlying maltodextrin acceptance and preference. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Digital vs. conventional full-arch implant impressions: a comparative study.

PubMed

Amin, Sarah; Weber, Hans Peter; Finkelman, Matthew; El Rafie, Khaled; Kudara, Yukio; Papaspyridakos, Panos

2017-11-01

To test whether or not digital full-arch implant impressions with two different intra-oral scanners (CEREC Omnicam and True Definition) have the same accuracy as conventional ones. The hypothesis was that the splinted open-tray impressions would be more accurate than digital full-arch impressions. A stone master cast representing an edentulous mandible using five internal connection implant analogs (Straumann Bone Level RC, Basel, Switzerland) was fabricated. The three median implants were parallel to each other, the far left implant had 10°, and the far right had 15° distal angulation. A splinted open-tray technique was used for the conventional polyether impressions (n = 10) for Group 1. Digital impressions (n = 10) were taken with two intra-oral optical scanners (CEREC Omnicam and 3M True Definition) after connecting polymer scan bodies to the master cast for groups 2 and 3. Master cast and conventional impression test casts were digitized with a high-resolution reference scanner (Activity 880 scanner; Smart Optics, Bochum, Germany) to obtain digital files. Standard tessellation language (STL) datasets from the three test groups of digital and conventional impressions were superimposed with the STL dataset from the master cast to assess the 3D deviations. Deviations were recorded as root-mean-square error. To compare the master cast with conventional and digital impressions at the implant level, Welch's F-test was used together with Games-Howell post hoc test. Group I had a mean value of 167.93 μm (SD 50.37); Group II (Omnicam) had a mean value of 46.41 μm (SD 7.34); Group III (True Definition) had a mean value of 19.32 μm (SD 2.77). Welch's F-test was used together with the Games-Howell test for post hoc comparisons. Welch's F-test showed a significant difference between the groups (P < 0.001). The Games-Howell test showed statistically significant 3D deviations for all three groups (P < 0.001). Full-arch digital implant impressions using True Definition scanner and Omnicam were significantly more accurate than the conventional impressions with the splinted open-tray technique. Additionally, the digital impressions with the True Definition scanner had significantly less 3D deviations when compared with the Omnicam. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Development, fabrication and test of a high purity silica heat shield

NASA Technical Reports Server (NTRS)

Rusert, E. L.; Drennan, D. N.; Biggs, M. S.

1978-01-01

A highly reflective hyperpure ( 25 ppm ion impurities) slip cast fused silica heat shield material developed for planetary entry probes was successfully scaled up. Process development activities for slip casting large parts included green strength improvements, casting slip preparation, aggregate casting, strength, reflectance, and subscale fabrication. Successful fabrication of a one-half scale Saturn probe (shape and size) heat shield was accomplished while maintaining the silica high purity and reflectance through the scale-up process. However, stress analysis of this original aggregate slip cast material indicated a small margin of safety (MS. = +4%) using a factor of safety of 1.25. An alternate hyperpure material formulation to increase the strength and toughness for a greater safety margin was evaluated. The alternate material incorporates short hyperpure silica fibers into the casting slip. The best formulation evaluated has a 50% by weight fiber addition resulting in an 80% increase in flexural strength and a 170% increase in toughness over the original aggregate slip cast materials with comparable reflectance.

Influence of rotational speed of centrifugal casting process on appearance, microstructure, and sliding wear behaviour of Al-2Si cast alloy

NASA Astrophysics Data System (ADS)

Mukunda, P. G.; Shailesh, Rao A.; Rao, Shrikantha S.

2010-02-01

Although the manner in which the molten metal flows plays a major role in the formation of the uniform cylinder in centrifugal casting, not much information is available on this topic. The flow in the molten metal differs at various rotational speeds, which in turn affects the final casting. In this paper, the influence of the flow of molten metal of hyper eutectic Al-2Si alloys at various rotational speeds is discussed. At an optimum speed of 800 rpm, a uniform cylinder was formed. For the rotational speeds below and above these speeds, an irregular shaped casting was formed, which is mainly due to the influence of melt. Primary á-Al particles were formed in the tube periphery at low rotational speed, and their sizes and shapes were altered with changes in rotational speeds. The wear test for the inner surface of the casting showed better wear properties for the casting prepared at the optimum speed of rotation.

ToxCast: Developing Predictive Signatures of Chemically Induced Toxicity (S)

EPA Science Inventory

ToxCast, the United States Environmental Protection Agency’s chemical prioritization research program, is developing methods for utilizing computational chemistry, bioactivity profiling and toxicogenomic data to predict potential for toxicity and prioritize limited testing resour...

Accuracy of six elastic impression materials used for complete-arch fixed partial dentures.

PubMed

Stauffer, J P; Meyer, J M; Nally, J N

1976-04-01

1. The accuracy of four types of impression materials used to make a complete-arch fixed partial denture was evaluated by visual comparison and indirect measurement methods. 2. None of the tested materials allows safe finishing of a complete-arch fixed partial denture on a cast poured from one single master impression. 3. All of the tested materials can be used for impressions for a complete-arch fixed partial denture provided it is not finished on one single cast. Errors can be avoided by making a new impression with the fitted castings in place. Assembly and soldering should be done on the second cast. 4. In making the master fixed partial denture for this study, inaccurate soldering was a problem that was overcome with the use of epoxy glue. Hence, soldering seems to be a major source of inaccuracy for every fixed partial denture.

Inter-arch digital model vs. manual cast measurements: Accuracy and reliability.

PubMed

Kiviahde, Heikki; Bukovac, Lea; Jussila, Päivi; Pesonen, Paula; Sipilä, Kirsi; Raustia, Aune; Pirttiniemi, Pertti

2017-06-28

The purpose of this study was to evaluate the accuracy and reliability of inter-arch measurements using digital dental models and conventional dental casts. Thirty sets of dental casts with permanent dentition were examined. Manual measurements were done with a digital caliper directly on the dental casts, and digital measurements were made on 3D models by two independent examiners. Intra-class correlation coefficients (ICC), a paired sample t-test or Wilcoxon signed-rank test, and Bland-Altman plots were used to evaluate intra- and inter-examiner error and to determine the accuracy and reliability of the measurements. The ICC values were generally good for manual and excellent for digital measurements. The Bland-Altman plots of all the measurements showed good agreement between the manual and digital methods and excellent inter-examiner agreement using the digital method. Inter-arch occlusal measurements on digital models are accurate and reliable and are superior to manual measurements.

Fatigue of die cast zinc alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schrems, K.K.; Dogan, O.N.; Goodwin, F.E.

2006-04-01

The rotating bending fatigue limit of die cast zinc alloy 2, alloy 3, alloy 5, AcuZinc 5, and ZA-8 were determined as a part of an on-going program by ILZRO into the mechanical properties of die cast zinc. The stress-life (S-N) curves of alloys 3, 5, AcuZinc 5, and ZA-8 were determined previously. This presentation reports the results of the S-N curve for Alloy 2 and the calculated fatigue limits for all five alloys. During the previous stress-life testing, the samples were stopped at 10 million cycles and the fatigue limit for alloy 3, alloy 5, and AcuZinc 5 appearedmore » to be higher and the fatigue limit for ZA-8 appeared to be lower than the values reported in the literature. This was further investigated in alloy 5 and ZA-8 by testing continuous cast bulk alloy 5 and ZA-8.« less

Fracture resistance of Ti-5Al-2.5Sn extra-low interstitial castings

NASA Technical Reports Server (NTRS)

Fiftal, C. F.; Bolstad, D. A.; Misra, M. S.

1978-01-01

Fracture toughness and cyclic crack propagation data for Ti-5Al-2.5Sn extra-low interstitial (ELI) castings, 0.51 and 2.54 cm (0.20 and 1.00 in.) thick, at 394, 294, 77, and 20 K (250, 70, -320, and -423 F), are presented. Both surface flaw and compact tension geometries were tested. Comparison is made with other titanium alloys in both wrought and cast forms. Crack propagation resistance is comparable to wrought Ti-5Al-2.5Sn ELI, even with the extremely coarse as-cast grain size encountered.

Rapid Model Fabrication and Testing for Aerospace Vehicles

NASA Technical Reports Server (NTRS)

Buck, Gregory M.

2000-01-01

Advanced methods for rapid fabrication and instrumentation of hypersonic wind tunnel models are being developed and evaluated at NASA Langley Research Center. Rapid aeroheating model fabrication and measurement techniques using investment casting of ceramic test models and thermographic phosphors are reviewed. More accurate model casting techniques for fabrication of benchmark metal and ceramic test models are being developed using a combination of rapid prototype patterns and investment casting. White light optical scanning is used for coordinate measurements to evaluate the fabrication process and verify model accuracy to +/- 0.002 inches. Higher-temperature (<210C) luminescent coatings are also being developed for simultaneous pressure and temperature mapping, providing global pressure as well as global aeroheating measurements. Together these techniques will provide a more rapid and complete experimental aerodynamic and aerothermodynamic database for future aerospace vehicles.

Cast iron-base alloy for cylinder/regenerator housing

NASA Technical Reports Server (NTRS)

Witter, Stewart L.; Simmons, Harold E.; Woulds, Michael J.

1985-01-01

NASACC-1 is a castable iron-base alloy designed to replace the costly and strategic cobalt-base X-40 alloy used in the automotive Stirling engine cylinder/generator housing. Over 40 alloy compositions were evaluated using investment cast test bars for stress-rupture testing. Also, hydrogen compatibility and oxygen corrosion resistance tests were used to determine the optimal alloy. NASACC-1 alloy was characterized using elevated and room temperature tensile, creep-rupture, low cycle fatigue, heat capacity, specific heat, and thermal expansion testing. Furthermore, phase analysis was performed on samples with several heat treated conditions. The properties are very encouraging. NASACC-1 alloy shows stress-rupture and low cycle fatigue properties equivalent to X-40. The oxidation resistance surpassed the program goal while maintaining acceptable resistance to hydrogen exposure. The welding, brazing, and casting characteristics are excellent. Finally, the cost of NASACC-1 is significantly lower than that of X-40.

Thermomechanical and bithermal fatigue behavior of cast B1900 + Hf and wrought Haynes 188

NASA Technical Reports Server (NTRS)

Halford, G. R.; Verrilli, M. J.; Kalluri, S.; Ritzert, F. J.; Duckert, R. E.; Holland, F. A.

1992-01-01

A thermomechanical fatigue (TMF) high-temperature life prediction method has been evaluated using the experimental data. Bithermal fatigue (BTF), bithermal creep-fatigue (BTC-F), and TMF experiments were performed using two aerospace structural alloys, cast B1900 + Hf and wrought Haynes 188. The method which is based on the total strain version of strain range partitioning and unified cyclic constitutive modeling requires, as an input, information on the flow and failure behavior of the material of interest. Bithermal temperatures of 483 and 871 C were used for the cast B1900 + Hf nickel-base alloy and 316 and 760 C for the wrought Haynes 188 cobalt-base alloy. Maximum and minimum temperatures were also used in both TMF and BTF tests. Comparisons were made between the results of these tests and isothermal tensile and fatigue test data obtained previously. Qualitative correlations were observed between tensile and isothermal fatigue tests.

Creep-rupture and fractographic analysis of candidate Stirling engine superalloys tested in air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhattachryya, S.

The creep-rupture behavior of six candidate Stirling engine iron-base superalloys was determined in air. The alloys tested included four wrought alloys (A-286, INCOLOY Alloy 800H, N-155, and 19-9DL) and two cast alloys (CRM-6D and XF-818). The wrought alloys were evaluated in the form of sheet; the cast alloy specimens were investment cast to shape. The creep-rupture specimens were tested in air for up to 3000 hours over the temperature range 650/sup 0/ to 925/sup 0/C. Microstructural and fractographic aspects of the ruptured specimens are discussed with a few correlational graphical analyses included for XF-818 and 19-9DL. Tests are continuing inmore » 15 MPa hydrogen, and later these data will be correlated with air data and microstructural analysis of the specimens conducted.« less

Corrosion behavior of cast Ti-6Al-4V alloyed with Cu.

PubMed

Koike, Marie; Cai, Zhuo; Oda, Yutaka; Hattori, Masayuki; Fujii, Hiroyuki; Okabe, Toru

2005-05-01

It has recently been found that alloying with copper improved the inherently poor grindability and wear resistance of titanium. This study characterized the corrosion behavior of cast Ti-6Al-4V alloyed with copper. Alloys (0.9 or 3.5 mass % Cu) were cast with the use of a magnesia-based investment in a centrifugal casting machine. Three specimen surfaces were tested: ground, sandblasted, and as cast. Commercially pure titanium and Ti-6Al-4V served as controls. Open-circuit potential measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air + 10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was conducted in the same medium deaerated by N(2) + 10% CO(2). Polarization resistance (R(p)), Tafel slopes, and corrosion current density (I(corr)) were determined. A passive region occurred for the alloy specimens with ground and sandblasted surfaces, as for CP Ti. However, no passivation was observed on the as-cast alloys or on CP Ti. There were significant differences among all metals tested for R(p) and I(corr) and significantly higher R(p) and lower I(corr) values for CP Ti compared to Ti-6Al-4V or the alloys with Cu. Alloying up to 3.5 mass % Cu to Ti-6Al-4V did not change the corrosion behavior. Specimens with ground or sandblasted surfaces were superior to specimens with as-cast surfaces. (c) 2005 Wiley Periodicals, Inc.

Early substance consumption and problematic use of video games in adolescence

PubMed Central

Coëffec, Adélaïde; Romo, Lucia; Cheze, Nathalie; Riazuelo, Hélène; Plantey, Sophie; Kotbagi, Gayatri; Kern, Laurence

2015-01-01

Substance use as well as use of video games is frequent among young people. The purpose of this research was to study the links between the use of video games and the consumption of various substances such as alcohol, tobacco or cannabis at adolescence. In order to do so, 1423 students from middle and high schools filled an auto-questionnaire that included questions on age, gender, year of study, use of video games and consumptions of alcohol (Alcohol Use Disorders Identification Test Short version, AUDIT-C), tobacco (Heaviness of Smoking Index, HSI), and cannabis (Cannabis Abuse Screening Test, CAST). We found that 92.1% of teens use video games and 17.7% have a problematic use of video games (PUVG). Furthermore, results show that substance consumption seems frequent with 19.8 and 8.3% of participants having hazardous alcohol and cannabis consumptions respectively and 5.2% having a moderate to high tobacco dependence. Video gamers consumed significantly more alcohol and gamers with PUVG started their substance consumption (alcohol, tobacco, and cannabis) earlier. PUVG was found to be negatively correlated to age at first substance consumption, but positively correlated to the time spent playing video games. However, it was not correlated to risks of substance dependence (scores of AUDIT-C, HSI, and CAST). Finally, our results are consistent with the literature, in regard to frequency of substance use and use of video games in adolescence. These data will allow for a better consideration of prevention strategies and future care in this particular field. PMID:25972826

Effect of Cold Forging on Microstructure and MechanicalProperties of Al/SiC Composites

NASA Astrophysics Data System (ADS)

Hanamantraygouda, M. B.; Shivakumar, B. P., Dr; Siddappa, P. N.; Sampathkumar, L.; Prashanth, L.

2018-02-01

The objective of this work was to investigate the effect of cold forging on mechanical properties and microstructural study of Al MMCs, at different wt% of SiC and forging cycle. The Al-SiC composite material was fabricated by stir casting method at different weight percentage of SiC such as 2.5, 5, 7.5 and 10%. Further, the deformation characteristics during open-die forging of Al-SiC composite at cold conditions was investigated. Cast and forged composite material was subjected to hardness test, tensile test and impact test. The grain size, microstructure behaviour was investigated using optical microscope. The results show that hardness and strength of Al-SiC composite increases and ductility decreases as compared to Al alloy in both as-cast and forged conditions. Optical microscope images showed that the distribution of SiC in Al matrix was more homogeneous in a forged composite as compared to cast one and reduction of porosity was found. Further, it showed that due to forging cycle the grain size was reduced by 30% to 35% from initial size.

Religion insulates ingroup evaluations: the development of intergroup attitudes in India.

PubMed

Dunham, Yarrow; Srinivasan, Mahesh; Dotsch, Ron; Barner, David

2014-03-01

Research on the development of implicit intergroup attitudes has placed heavy emphasis on race, leaving open how social categories that are prominent in other cultures might operate. We investigate two of India's primary means of social distinction, caste and religion, and explore the development of implicit and explicit attitudes towards these groups in minority-status Muslim children and majority-status Hindu children, the latter drawn from various positions in the Hindu caste system. Results from two tests of implicit attitudes find that caste attitudes parallel previous findings for race: higher-caste children as well as lower-caste children have robust high-caste preferences. However, results for religion were strikingly different: both lower-status Muslim children and higher-status Hindu children show strong implicit ingroup preferences. We suggest that religion may play a protective role in insulating children from the internalization of stigma. © 2013 John Wiley & Sons Ltd.

Acute antibody-directed myostatin inhibition attenuates disuse muscle atrophy and weakness in mice.

PubMed

Murphy, Kate T; Cobani, Vera; Ryall, James G; Ibebunjo, Chikwendu; Lynch, Gordon S

2011-04-01

Counteracting the atrophy of skeletal muscle associated with disuse has significant implications for minimizing the wasting and weakness in plaster casting, joint immobilization, and other forms of limb unloading, with relevance to orthopedics, sports medicine, and plastic and reconstructive surgery. We tested the hypothesis that antibody-directed myostatin inhibition would attenuate the loss of muscle mass and functional capacity in mice during 14 or 21 days of unilateral hindlimb casting. Twelve-week-old C57BL/10 mice were subjected to unilateral hindlimb plaster casting or served as controls. Mice received subcutaneous injections of saline or a mouse chimera of anti-human myostatin antibody (PF-354, 10 mg/kg; n = 6-9) on days 0 and 7 and were tested for muscle function on day 14, or were treated on days 0, 7, and 14 and tested for muscle function on day 21. Hindlimb casting reduced muscle mass, fiber size, and function of isolated soleus and extensor digitorum longus (EDL) muscles (P < 0.05). PF-354 attenuated the loss of muscle mass, fiber size, and function with greater effects after 14 days than after 21 days of casting, when wasting and weakness had plateaued (P < 0.05). Antibody-directed myostatin inhibition therefore attenuated the atrophy and loss of functional capacity in muscles from mice subjected to unilateral hindlimb casting with reductions in muscle size and strength being most apparent during the first 14 days of disuse. These findings highlight the therapeutic potential of antibody-directed myostatin inhibition for disuse atrophy especially within the first 2 wk of disuse.

Pesticide presence in Great Lakes tributaries and comparison to ToxCast and other water quality benchmarks to screen for potential biological effects

EPA Science Inventory

Product Description:Pesticides are a broad category of current use chemicals that pose potential threats to aquatic organisms in and around the Great Lakes basin. In this study, we monitored for over 200 pesticides or their break down products in 16 major tributaries to the Great...

Development of High-Performance Cast Crankshafts. Final Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bauer, Mark E

The objective of this project was to develop technologies that would enable the production of cast crankshafts that can replace high performance forged steel crankshafts. To achieve this, the Ultimate Tensile Strength (UTS) of the new material needs to be 850 MPa with a desired minimum Yield Strength (YS; 0.2% offset) of 615 MPa and at least 10% elongation. Perhaps more challenging, the cast material needs to be able to achieve sufficient local fatigue properties to satisfy the durability requirements in today’s high performance gasoline and diesel engine applications. The project team focused on the development of cast steel alloysmore » for application in crankshafts to take advantage of the higher stiffness over other potential material choices. The material and process developed should be able to produce high-performance crankshafts at no more than 110% of the cost of current production cast units, perhaps the most difficult objective to achieve. To minimize costs, the primary alloy design strategy was to design compositions that can achieve the required properties with minimal alloying and post-casting heat treatments. An Integrated Computational Materials Engineering (ICME) based approach was utilized, rather than relying only on traditional trial-and-error methods, which has been proven to accelerate alloy development time. Prototype melt chemistries designed using ICME were cast as test specimens and characterized iteratively to develop an alloy design within a stage-gate process. Standard characterization and material testing was done to validate the alloy performance against design targets and provide feedback to material design and manufacturing process models. Finally, the project called for Caterpillar and General Motors (GM) to develop optimized crankshaft designs using the final material and manufacturing processing path developed. A multi-disciplinary effort was to integrate finite element analyses by engine designers and geometry-specific casting simulations with existing materials models to optimize crankshaft cost and performance. Prototype crankshafts of the final design were to be produced and validated using laboratory bench testing and on-engine durability testing. ICME process simulation tools were used to investigate a broad range of processing concepts. These concepts included casting orientation, various mold and core materials, and various filling and feeding strategies. Each crankshaft was first simulated without gating and risers, which is termed natural solidification. The natural solidification results were used as a baseline for strategy development of each concept. Casting process simulations and ICME tools were proven to be reasonable predictors of real world results. Potential alloys were developed that could meet the project material property goals with appropriate normalization and temper treatments. For the alloys considered, post-normalization temper treatments proved to be necessary to achieve the desired yield strengths and elongations and appropriate heat treatments were designed using ICME tools. The experimental data of all the alloys were analyzed in combination with ICME tools to establish chemistry-process-structure relations. Several GM small gas engine (SGE) crankshafts were successfully cast in sand molds using two different sprue, runner, gate, riser, chill designs. These crankshafts were cast in two different steel alloys developed during the project, but casting finishing (e.g. riser removal) remains a cost challenge. A long list of future work was left unfinished when this project was unexpectedly terminated.« less

14 CFR 27.621 - Casting factors.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS.... The factors, tests, and inspections specified in paragraphs (b) and (c) of this section must be... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings except...

14 CFR 27.621 - Casting factors.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS.... The factors, tests, and inspections specified in paragraphs (b) and (c) of this section must be... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings except...

14 CFR 27.621 - Casting factors.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS.... The factors, tests, and inspections specified in paragraphs (b) and (c) of this section must be... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings except...

Field testing of jet-grouted pile : [summary].

DOT National Transportation Integrated Search

2014-01-01

In many areas of Florida, local geology dictates the use of deep foundations for transportation structures bridges, noise walls, signage, etc. When concrete piles are used, they are either prestressed at the casting yard, cast in situ through a h...

Feature Analysis of ToxCast Compounds

EPA Science Inventory

ToxCast was initiated by the US Environmental Protection Agency (EPA) to prioritize environmental chemicals for toxicity testing. Phase I generated data for 309 unique chemicals, mostly pesticide actives, that span diverse chemical feature/property space, as determined by quantu...

Effect of iron-intermetallics and porosity on tensile and impact properties of aluminum-silicon-copper and aluminum-silicon-magnesium cast alloys

NASA Astrophysics Data System (ADS)

Ma, Zheyuan

Aluminum-silicon (Al-Si) alloys are an important class of materials that constitute the majority of aluminum cast parts produced, due to their superior properties and excellent casting characteristics. Within this family of alloys, Al-Si-Cu and Al-Si-Mg cast alloys are frequently employed in automotive applications. The commercially popular 319 and 356 alloys, representing these two alloy systems, were selected for study in the present work, with the aim of investigating the effect of iron intermetallics and porosity on the alloy performance. This was carried out through a study of the tensile and impact properties, these being two of the important mechanical properties used in design calculations. Iron, through the precipitation of second phase intermetallic constituents, in particular the platelike beta-Al5FeSi phase, is harmful to the alloy properties. Likewise, gas- or shrinkage porosity in castings is also detrimental to the mechanical properties. By determining the optimum alloying, melt processing and solidification parameters (viz., Fe content, Sr modification and cooling rate) required to minimize the harmful effects of porosity and iron intermetallics, and studying their role on the fracture behavior, the fracture mechanism in the alloys could be determined. Castings were prepared from both industrial and experimental 319.2, B319.2 and A356.2 alloy melts, containing Fe levels of 0.2--1.0 wt%. Sr-modified (˜200 ppm) melts were also prepared for each alloy Fe level. The end-chilled refractory mold used provided directional solidification and a range of cooling rates (or dendrite arm spacings, DAS) within the same casting. Tensile and impact test samples machined from specimen blanks sectioned from the castings at various heights above the chill end provided DASs of 23--85mum. All samples were T6-heat-treated before testing. Tests were carried out employing Instron Universal and Instrumented Charpy testing machines. Optical microscopy, image analysis, SEM and EPMA techniques were used for microstructural and fracture analysis. The results show that the highest cooling rate (23 mum DAS) is the most significant parameter controlling the size and distribution of the beta-Al 5FeSi phase and porosity in the unmodified 319.2 and A356.2 alloys. (Abstract shortened by UMI.)

Amperometric Biosensor Based on Zirconium Oxide/Polyethylene Glycol/Tyrosinase Composite Film for the Detection of Phenolic Compounds.

PubMed

Ahmad, Nor Monica; Abdullah, Jaafar; Yusof, Nor Azah; Ab Rashid, Ahmad Hazri; Abd Rahman, Samsulida; Hasan, Md Rakibul

2016-06-29

A phenolic biosensor based on a zirconium oxide/polyethylene glycol/tyrosinase composite film for the detection of phenolic compounds has been explored. The formation of the composite film was expected via electrostatic interaction between hexacetyltrimethylammonium bromide (CTAB), polyethylene glycol (PEG), and zirconium oxide nanoparticles casted on screen printed carbon electrode (SPCE). Herein, the electrode was treated by casting hexacetyltrimethylammonium bromide on SPCE to promote a positively charged surface. Later, zirconium oxide was mixed with polyethylene glycol and the mixture was dropped cast onto the positively charged SPCE/CTAB. Tyrosinase was further immobilized onto the modified SPCE. Characterization of the prepared nanocomposite film and the modified SPCE surface was investigated by scanning electron microscopy (SEM), Electrochemical Impedance Spectroscopy (EIS), and Cyclic voltamogram (CV). The developed biosensor exhibits rapid response for less than 10 s. Two linear calibration curves towards phenol in the concentrations ranges of 0.075-10 µM and 10-55 µM with the detection limit of 0.034 µM were obtained. The biosensor shows high sensitivity and good storage stability for at least 30 days.

A gene expression biomarker accurately predicts estrogen ...

EPA Pesticide Factsheets

The EPA’s vision for the Endocrine Disruptor Screening Program (EDSP) in the 21st Century (EDSP21) includes utilization of high-throughput screening (HTS) assays coupled with computational modeling to prioritize chemicals with the goal of eventually replacing current Tier 1 screening tests. The ToxCast program currently includes 18 HTS in vitro assays that evaluate the ability of chemicals to modulate estrogen receptor α (ERα), an important endocrine target. We propose microarray-based gene expression profiling as a complementary approach to predict ERα modulation and have developed computational methods to identify ERα modulators in an existing database of whole-genome microarray data. The ERα biomarker consisted of 46 ERα-regulated genes with consistent expression patterns across 7 known ER agonists and 3 known ER antagonists. The biomarker was evaluated as a predictive tool using the fold-change rank-based Running Fisher algorithm by comparison to annotated gene expression data sets from experiments in MCF-7 cells. Using 141 comparisons from chemical- and hormone-treated cells, the biomarker gave a balanced accuracy for prediction of ERα activation or suppression of 94% or 93%, respectively. The biomarker was able to correctly classify 18 out of 21 (86%) OECD ER reference chemicals including “very weak” agonists and replicated predictions based on 18 in vitro ER-associated HTS assays. For 114 chemicals present in both the HTS data and the MCF-7 c

Alloy Design and Development of Cast Cr-W-V Ferritic Steels for Improved High-Temperature Strength for Power Generation Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klueh, R L; Maziasz, P J; Vitek, J M

2006-09-23

Economic and environmental concerns demand that the power-generation industry seek increased efficiency for gas turbines. Higher efficiency requires higher operating temperatures, with the objective temperature for the hottest sections of new systems {approx} 593 C, and increasing to {approx} 650 C. Because of their good thermal properties, Cr-Mo-V cast ferritic steels are currently used for components such as rotors, casings, pipes, etc., but new steels are required for the new operating conditions. The Oak Ridge National Laboratory (ORNL) has developed new wrought Cr-W-V steels with 3-9% Cr, 2-3% W, 0.25% V (compositions are in wt.%), and minor amounts of additionalmore » elements. These steels have the strength and toughness required for turbine applications. Since cast alloys are expected to behave differently from wrought material, work was pursued to develop new cast steels based on the ORNL wrought compositions. Nine casting test blocks with 3, 9, and 11% Cr were obtained. Eight were Cr-W-V-Ta-type steels based on the ORNL wrought steels; the ninth was COST CB2, a 9Cr-Mo-Co-V-Nb cast steel, which was the most promising cast steel developed in a European alloy-development program. The COST CB2 was used as a control to which the new compositions were compared, and this also provided a comparison between Cr-W-V-Ta and Cr-Mo-V-Nb compositions. Heat treatment studies were carried out on the nine castings to determine normalizing-and-tempering treatments. Microstructures were characterized by both optical and transmission electron microscopy (TEM). Tensile, impact, and creep tests were conducted. Test results on the first nine cast steel compositions indicated that properties of the 9Cr-Mo-Co-V-Nb composition of COST CB2 were better than those of the 3Cr-, 9Cr-, and 11Cr-W-V-Ta steels. Analysis of the results of this first iteration using computational thermodynamics raised the question of the effectiveness in cast steels of the Cr-W-V-Ta combination versus the Cr-Mo-V-Nb combination in COST CB2. To explore this question, nine more casting test blocks, four 3Cr steels and five 11Cr steels were purchased, and microstructure and mechanical properties studies similar to those described above for the first iteration of test blocks were conducted. Experimental results from the second iteration indicated that 11 Cr steels with excellent properties are possible. The 11Cr-1.5Mo-V-Nb steels were superior to 11Cr-2W-V-Ta steels, and it appears the former class of steels can be developed to have tensile and creep properties exceeding those of COST CB2. The W-Nb combination in an 11Cr-2W-V-Nb steel had tensile and short-time creep properties at 650 C better than the 11Cr-1.5Mo-V-Nb steels, although long-time low-stress properties may not be as good because of Laves phase formation. Based on the results, the next step in the development of improved casting steels involves acquisition of 11Cr-1.5Mo-V-Nb-N-B-C and 11Cr-2W-V-Nb-N-B-C steels on which long-term creep-rupture tests (>10,000 h) be conducted. For better oxidation and corrosion resistance, development of 11Cr steels, as opposed to a 9Cr steels, such as COST CB2, are important for future turbine designs that envision operating temperatures of 650 C.« less

Secondary Waste Form Screening Test Results—THOR® Fluidized Bed Steam Reforming Product in a Geopolymer Matrix

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pires, Richard P.; Westsik, Joseph H.; Serne, R. Jeffrey

2011-07-14

Screening tests are being conducted to evaluate waste forms for immobilizing secondary liquid wastes from the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Plans are underway to add a stabilization treatment unit to the Effluent Treatment Facility to provide the needed capacity for treating these wastes from WTP. The current baseline is to use a Cast Stone cementitious waste form to solidify the wastes. Through a literature survey, DuraLith alkali-aluminosilicate geopolymer, fluidized-bed steam reformation (FBSR) granular product encapsulated in a geopolymer matrix, and a Ceramicrete phosphate-bonded ceramic were identified both as candidate waste forms and alternatives to the baseline.more » These waste forms have been shown to meet waste disposal acceptance criteria, including compressive strength and universal treatment standards for Resource Conservation and Recovery Act (RCRA) metals (as measured by the toxicity characteristic leaching procedure [TCLP]). Thus, these non-cementitious waste forms should also be acceptable for land disposal. Information is needed on all four waste forms with respect to their capability to minimize the release of technetium. Technetium is a radionuclide predicted to be in the secondary liquid wastes in small quantities, but the Integrated Disposal Facility (IDF) risk assessment analyses show that technetium, even at low mass, produces the largest contribution to the estimated IDF disposal impacts to groundwater.« less

DARC: Mapping Surface Topography by Ray-Casting for Effective Virtual Screening at Protein Interaction Sites.

PubMed

Gowthaman, Ragul; Miller, Sven A; Rogers, Steven; Khowsathit, Jittasak; Lan, Lan; Bai, Nan; Johnson, David K; Liu, Chunjing; Xu, Liang; Anbanandam, Asokan; Aubé, Jeffrey; Roy, Anuradha; Karanicolas, John

2016-05-12

Protein-protein interactions represent an exciting and challenging target class for therapeutic intervention using small molecules. Protein interaction sites are often devoid of the deep surface pockets presented by "traditional" drug targets, and crystal structures reveal that inhibitors typically engage these sites using very shallow binding modes. As a consequence, modern virtual screening tools developed to identify inhibitors of traditional drug targets do not perform as well when they are instead deployed at protein interaction sites. To address the need for novel inhibitors of important protein interactions, here we introduce an alternate docking strategy specifically designed for this regime. Our method, termed DARC (Docking Approach using Ray-Casting), matches the topography of a surface pocket "observed" from within the protein to the topography "observed" when viewing a potential ligand from the same vantage point. We applied DARC to carry out a virtual screen against the protein interaction site of human antiapoptotic protein Mcl-1 and found that four of the top-scoring 21 compounds showed clear inhibition in a biochemical assay. The Ki values for these compounds ranged from 1.2 to 21 μM, and each had ligand efficiency comparable to promising small-molecule inhibitors of other protein-protein interactions. These hit compounds do not resemble the natural (protein) binding partner of Mcl-1, nor do they resemble any known inhibitors of Mcl-1. Our results thus demonstrate the utility of DARC for identifying novel inhibitors of protein-protein interactions.

West Eurasian mtDNA lineages in India: an insight into the spread of the Dravidian language and the origins of the caste system.

PubMed

Palanichamy, Malliya Gounder; Mitra, Bikash; Zhang, Cai-Ling; Debnath, Monojit; Li, Gui-Mei; Wang, Hua-Wei; Agrawal, Suraksha; Chaudhuri, Tapas Kumar; Zhang, Ya-Ping

2015-06-01

There is no indication from the previous mtDNA studies that west Eurasian-specific subclades have evolved within India and played a role in the spread of languages and the origins of the caste system. To address these issues, we have screened 14,198 individuals (4208 from this study) and analyzed 112 mitogenomes (41 new sequences) to trace west Eurasian maternal ancestry. This has led to the identification of two autochthonous subhaplogroups--HV14a1 and U1a1a4, which are likely to have originated in the Dravidian-speaking populations approximately 10.5-17.9 thousand years ago (kya). The carriers of these maternal lineages might have settled in South India during the time of the spread of the Dravidian language. In addition to this, we have identified several subsets of autochthonous U7 lineages, including U7a1, U7a2b, U7a3, U7a6, U7a7, and U7c, which seem to have originated particularly in the higher-ranked caste populations in relatively recent times (2.6-8.0 kya with an average of 5.7 kya). These lineages have provided crucial clues to the differentiation of the caste system that has occurred during the recent past and possibly, this might have been influenced by the Indo-Aryan migration. The remaining west Eurasian lineages observed in the higher-ranked caste groups, like the Brahmins, were found to cluster with populations who possibly arrived from west Asia during more recent times.

Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool.

PubMed

Paiva, Jose Mario; Fox-Rabinovich, German; Locks Junior, Edinei; Stolf, Pietro; Seid Ahmed, Yassmin; Matos Martins, Marcelo; Bork, Carlos; Veldhuis, Stephen

2018-02-28

In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si₃N₄ nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

14 CFR 25.621 - Casting factors.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS...) General. The factors, tests, and inspections specified in paragraphs (b) through (d) of this section must... meet approved specifications. Paragraphs (c) and (d) of this section apply to any structural castings...

14 CFR 25.621 - Casting factors.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS...) General. The factors, tests, and inspections specified in paragraphs (b) through (d) of this section must... meet approved specifications. Paragraphs (c) and (d) of this section apply to any structural castings...

14 CFR 29.621 - Casting factors.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS...) General. The factors, tests, and inspections specified in paragraphs (b) and (c) of this section must be... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings except...

14 CFR 25.621 - Casting factors.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS...) General. The factors, tests, and inspections specified in paragraphs (b) through (d) of this section must... meet approved specifications. Paragraphs (c) and (d) of this section apply to any structural castings...

14 CFR 25.621 - Casting factors.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS...) General. The factors, tests, and inspections specified in paragraphs (b) through (d) of this section must... meet approved specifications. Paragraphs (c) and (d) of this section apply to any structural castings...

14 CFR 29.621 - Casting factors.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS...) General. The factors, tests, and inspections specified in paragraphs (b) and (c) of this section must be... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings except...

14 CFR 25.621 - Casting factors.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS...) General. The factors, tests, and inspections specified in paragraphs (b) through (d) of this section must... meet approved specifications. Paragraphs (c) and (d) of this section apply to any structural castings...

14 CFR 29.621 - Casting factors.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS...) General. The factors, tests, and inspections specified in paragraphs (b) and (c) of this section must be... approved specifications. Paragraphs (c) and (d) of this section apply to structural castings except...

Precision Modeling Of Targets Using The VALUE Computer Program

NASA Astrophysics Data System (ADS)

Hoffman, George A.; Patton, Ronald; Akerman, Alexander

1989-08-01

The 1976-vintage LASERX computer code has been augmented to produce realistic electro-optical images of targets. Capabilities lacking in LASERX but recently incorporated into its VALUE successor include: •Shadows cast onto the ground •Shadows cast onto parts of the target •See-through transparencies (e.g.,canopies) •Apparent images due both to atmospheric scattering and turbulence •Surfaces characterized by multiple bi-directional reflectance functions VALUE provides not only realistic target modeling by its precise and comprehensive representation of all target attributes, but additionally VALUE is very user friendly. Specifically, setup of runs is accomplished by screen prompting menus in a sequence of queries that is logical to the user. VALUE also incorporates the Optical Encounter (OPEC) software developed by Tricor Systems,Inc., Elgin, IL.

Does the casting mode influence microstructure, fracture and properties of different metal ceramic alloys?

PubMed

Bauer, José Roberto de Oliveira; Grande, Rosa Helena Miranda; Rodrigues-Filho, Leonardo Eloy; Pinto, Marcelo Mendes; Loguercio, Alessandro Dourado

2012-01-01

The aim of the present study was to evaluate the tensile strength, elongation, microhardness, microstructure and fracture pattern of various metal ceramic alloys cast under different casting conditions. Two Ni-Cr alloys, Co-Cr and Pd-Ag were used. The casting conditions were as follows: electromagnetic induction under argon atmosphere, vacuum, using blowtorch without atmosphere control. For each condition, 16 specimens, each measuring 25 mm long and 2.5 mm in diameter, were obtained. Ultimate tensile strength (UTS) and elongation (EL) tests were performed using a Kratos machine. Vickers Microhardness (VM), fracture mode and microstructure were analyzed by SEM. UTS, EL and VM data were statistically analyzed using ANOVA. For UTS, alloy composition had a direct influence on casting condition of alloys (Wiron 99 and Remanium CD), with higher values shown when cast with Flame/Air (p < 0.05). The factors 'alloy" and 'casting condition" influenced the EL and VM results, generally presenting opposite results, i.e., alloy with high elongation value had lower hardness (Wiron 99), and casting condition with the lowest EL values had the highest VM values (blowtorch). Both factors had significant influence on the properties evaluated, and prosthetic laboratories should select the appropriate casting method for each alloy composition to obtain the desired property.

Effect of casting atmosphere on the marginal deficiency and misfit of Ni-Cr alloys with and without beryllium.

PubMed

da Silva, Leandro J; Leal, Monica B; Valente, Mariana L C; de Castro, Denise T; Pagnano, Valéria O; Dos Reis, Andréa C; Bezzon, Osvaldo L

2017-07-01

The marginal adaptation of prosthetic crowns is still a significant clinical problem. The purpose of this in vitro study was to evaluate the marginal deficiency and misfit of Ni-Cr alloys with and without beryllium under different casting conditions. Four casting conditions were selected: flame-torch, induction/argon, induction/vacuum, and induction/air; and 2 alloys were used, Ni-Cr-Be and Ni-Cr. For each group, 10 metal specimens were prepared. Silicone indirect impressions and analysis of the degree of rounding were used to evaluate the marginal deficiencies of metal copings, and a standardized device for the setting pressure associated with optical microscopy was used to analyze the marginal misfit. Results were evaluated with 2-way ANOVA (α=.05), followed by the Tukey honest significant difference post hoc test, and the Pearson correlation test (α=.05). Alloy (P<.001) and casting technique (P<.001) were shown to affect marginal deficiencies. The Ni-Cr cast using the torch technique showed the highest marginal deficiency, and the Ni-Cr-Be cast in a controlled argon atmosphere showed the lowest (P<.001). Alloy (P=.472) and casting techniques (P=.206) did not affect the marginal misfit, but significant differences were found in the interaction (P=.001); the lowest misfit was achieved using the Ni-Cr-Be, and the highest misfit occurred with the molten Ni-Cr, using the cast torch technique. No correlation was found between deficiency and marginal misfit (r=.04, P=.69). The interactions demonstrated that the alloy containing beryllium that was cast in an argon atmosphere led to reduced marginal deficiency. Improved marginal adaptation can be achieved for the same alloy by using the torch technique. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Development and evaluation of a digital dental modeling method based on grating projection and reverse engineering software.

PubMed

Zhou, Qin; Wang, Zhenzhen; Chen, Jun; Song, Jun; Chen, Lu; Lu, Yi

2016-01-01

For reasons of convenience and economy, attempts have been made to transform traditional dental gypsum casts into 3-dimensional (3D) digital casts. Different scanning devices have been developed to generate digital casts; however, each has its own limitations and disadvantages. The purpose of this study was to develop an advanced method for the 3D reproduction of dental casts by using a high-speed grating projection system and noncontact reverse engineering (RE) software and to evaluate the accuracy of the method. The methods consisted of 3 main steps: the scanning and acquisition of 3D dental cast data with a high-resolution grating projection system, the reconstruction and measurement of digital casts with RE software, and the evaluation of the accuracy of this method using 20 dental gypsum casts. The common anatomic landmarks were measured directly on the gypsum casts with a Vernier caliper and on the 3D digital casts with the Geomagic software measurement tool. Data were statistically assessed with the t test. The grating projection system had a rapid scanning speed, and smooth 3D dental casts were obtained. The mean differences between the gypsum and 3D measurements were approximately 0.05 mm, and no statistically significant differences were found between the 2 methods (P>.05), except for the measurements of the incisor tooth width and maxillary arch length. A method for the 3D reconstruction of dental casts was developed by using a grating projection system and RE software. The accuracy of the casts generated using the grating projection system was comparable with that of the gypsum casts. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Focused Molding Using Adhesive Pads in Mehta Casting for Early-Onset Scoliosis.

PubMed

Abraham, Roby; Sponseller, Paul D

2014-11-01

Prospective clinical series. To determine the effect of adhesive pads placed over the apex of scoliosis curves on curve correction 1) after the first cast and 2) after the final cast. Early-onset scoliosis is often effectively managed by serial casting. Properly localizing the apex of the molds with the cast in place is challenging. The authors explored the effectiveness of a novel technique: incorporation of adhesive pads placed over the major curve apex before Mehta casting. The 27 patients who received body casts (2000-2013) were divided into 2 groups: those without and with apical adhesive pads (5-6 layers of pads placed on the major curve's apex during casting): non-pad (NP) group (n = 12) and pad (P) group (n = 15), respectively. Groups were compared regarding the percentage of Cobb angle change from the first cast and curve correction to a Cobb angle of <25° with Student t and chi-square tests (significance was p < .05). The mean percentage of major first-cast curve correction was 39% ± 18% and 56% ± 17% in the NP and P groups, respectively. Of the 26 patients out of a cast, 11 (42%) had a Cobb angle of <25°: 3 (25%) and 8 (57%) in the NP and P groups, respectively. The mean differences between the 2 groups in percentage of major curve correction and this Cobb angle correction were significant: p = .023 and .005, respectively. Adhesive pads placed over major curve(s) during Mehta casting were effective in increasing the amount of major curve correction from the first cast for idiopathic early-onset scoliosis and in decreasing curves to <25° at final follow-up. Copyright © 2014 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.

Factors contributing to the temperature beneath plaster or fiberglass cast material

PubMed Central

Hutchinson, Michael J; Hutchinson, Mark R

2008-01-01

Background Most cast materials mature and harden via an exothermic reaction. Although rare, thermal injuries secondary to casting can occur. The purpose of this study was to evaluate factors that contribute to the elevated temperature beneath a cast and, more specifically, evaluate the differences of modern casting materials including fiberglass and prefabricated splints. Methods The temperature beneath various types (plaster, fiberglass, and fiberglass splints), brands, and thickness of cast material were measured after they were applied over thermometer which was on the surface of a single diameter and thickness PVC tube. A single layer of cotton stockinette with variable layers and types of cast padding were placed prior to application of the cast. Serial temperature measurements were made as the cast matured and reached peak temperature. Time to peak, duration of peak, and peak temperature were noted. Additional tests included varying the dip water temperature and assessing external insulating factors. Ambient temperature, ambient humidity and dip water freshness were controlled. Results Outcomes revealed that material type, cast thickness, and dip water temperature played key roles regarding the temperature beneath the cast. Faster setting plasters achieved peak temperature quicker and at a higher level than slower setting plasters. Thicker fiberglass and plaster casts led to greater peak temperature levels. Likewise increasing dip-water temperature led to elevated temperatures. The thickness and type of cast padding had less of an effect for all materials. With a definition of thermal injury risk of skin injury being greater than 49 degrees Celsius, we found that thick casts of extra fast setting plaster consistently approached dangerous levels (greater than 49 degrees for an extended period). Indeed a cast of extra-fast setting plaster, 20 layers thick, placed on a pillow during maturation maintained temperatures over 50 degrees of Celsius for over 20 minutes. Conclusion Clinicians should be cautious when applying thick casts with warm dip water. Fast setting plasters have increased risk of thermal injury while brand does not appear to play a significant role. Prefabricated fiberglass splints appear to be safer than circumferential casts. The greatest risk of thermal injury occurs when thick casts are allowed to mature while resting on pillow. PMID:18298851

Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

DOE PAGES

Stromme, Eric T.; Henderson, Hunter B.; Sims, Zachary C.; ...

2018-04-25

Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatmentmore » line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. Furthermore, this work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments.« less

Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

NASA Astrophysics Data System (ADS)

Stromme, Eric T.; Henderson, Hunter B.; Sims, Zachary C.; Kesler, Michael S.; Weiss, David; Ott, Ryan T.; Meng, Fanqiang; Kassoumeh, Sam; Evangelista, James; Begley, Gerald; Rios, Orlando

2018-06-01

Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatment line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. This work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments.

Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

NASA Astrophysics Data System (ADS)

Stromme, Eric T.; Henderson, Hunter B.; Sims, Zachary C.; Kesler, Michael S.; Weiss, David; Ott, Ryan T.; Meng, Fanqiang; Kassoumeh, Sam; Evangelista, James; Begley, Gerald; Rios, Orlando

2018-04-01

Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatment line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. This work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments.

Ageless Aluminum-Cerium-Based Alloys in High-Volume Die Casting for Improved Energy Efficiency

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stromme, Eric T.; Henderson, Hunter B.; Sims, Zachary C.

Strong chemical reactions between Al and Ce lead to the formation of intermetallics with exceptional thermal stability. The rapid formation of intermetallics directly from the liquid phase during solidification of Al-Ce alloys leads to an ultrafine microconstituent structure that effectively strengthens as-cast alloys without further microstructural optimization via thermal processing. Die casting is a high-volume manufacturing technology that accounts for greater than 40% of all cast Al products, whereas Ce is highly overproduced as a waste product of other rare earth element (REE) mining. Reducing heat treatments would stimulate significant improvements in manufacturing energy efficiency, exceeding (megatonnes/year) per large-scale heat-treatmentmore » line. In this study, multiple compositions were evaluated with wedge mold castings to test the sensitivity of alloys to the variable solidification rate inherent in high-pressure die casting. Once a suitable composition was determined, it was successfully demonstrated at 800 lbs/h in a 600-ton die caster, after which the as-die cast parts performed similarly to ubiquitous A380 in the same geometry without requiring heat treatment. Furthermore, this work demonstrates the compatibility of Al REE alloys with high-volume die-casting applications with minimal heat treatments.« less

AMCC casting development. Volume 1: Executive Summary

NASA Technical Reports Server (NTRS)

1995-01-01

The Advanced Combustion Chamber Casting (AMCC) has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or Thermal Gradient Control. This method, of setting up thermal gradients in the casting during solidification, represents a significant process improvement for PCC and has been successfully implemented on other programs. Metallurgical integrity of the final four castings was very good. Only the areas of the parts that utilized 'TGC Shape & Location System #2' showed any significant areas of microshrinkage when evaluated by non-destructive tests. Alumina oxides detected by FPI on the 'float' surfaces (top sid surfaces of the casting during solidification) of the part were almost entirely less than the acceptance criteria of .032 inches in diameter. Destructive chem mill of the castings was required to determine the effect of the process variables used during the processing of these last four parts (with the exception of the 'Shape & Location of TGC' variable).

Corrosion behaviours of the dental magnetic keeper complexes made by different alloys and methods.

PubMed

Wu, Min-Ke; Song, Ning; Liu, Fei; Kou, Liang; Lu, Xiao-Wen; Wang, Min; Wang, Hang; Shen, Jie-Fei

2016-09-29

The keeper and cast dowel-coping, as a primary component for a magnetic attachment, is easily subjected to corrosion in a wet environment, such as the oral cavity, which contains electrolyte-rich saliva, complex microflora and chewing behaviour and so on. The objective of this in vitro study was to examine the corrosion resistance of a dowel and coping-keeper complex fabricated by finish keeper and three alloys (cobalt-chromium, CoCr; silver-palladium-gold, PdAu; gold-platinum, AuPt) using a laser-welding process and a casting technique. The surface morphology characteristics and microstructures of the samples were examined by means of metallographic microscope and scanning electron microscope (SEM). Energy-dispersive spectroscopy (EDS) with SEM provided elements analysis information for the test samples after 10% oxalic acid solution etching test. Tafel polarization curve recordings demonstrated parameter values indicating corrosion of the samples when subjected to electrochemical testing. This study has suggested that massive oxides are attached to the surface of the CoCr-keeper complex but not to the AuPt-keeper complex. Only the keeper area of cast CoCr-keeper complex displayed obvious intergranular corrosion and changes in the Fe and Co elements. Both cast and laser-welded AuPt-keeper complexes had the highest free corrosion potential, followed by the PdAu-keeper complex. We concluded that although the corrosion resistance of the CoCr-keeper complex was worst, the keeper surface passive film was actually preserved to its maximum extent. The laser-welded CoCr- and PdAu-keeper complexes possessed superior corrosion resistance as compared with their cast specimens, but no significant difference was found between the cast and laser-welded AuPt-keeper complexes. The Fe-poor and Cr-rich band, appearing on the edge of the keeper when casting, has been proven to be a corrosion-prone area.

Corrosion behaviours of the dental magnetic keeper complexes made by different alloys and methods

PubMed Central

Wu, Min-Ke; Song, Ning; Liu, Fei; Kou, Liang; Lu, Xiao-Wen; Wang, Min; Wang, Hang; Shen, Jie-Fei

2016-01-01

The keeper and cast dowel–coping, as a primary component for a magnetic attachment, is easily subjected to corrosion in a wet environment, such as the oral cavity, which contains electrolyte-rich saliva, complex microflora and chewing behaviour and so on. The objective of this in vitro study was to examine the corrosion resistance of a dowel and coping-keeper complex fabricated by finish keeper and three alloys (cobalt–chromium, CoCr; silver–palladium–gold, PdAu; gold–platinum, AuPt) using a laser-welding process and a casting technique. The surface morphology characteristics and microstructures of the samples were examined by means of metallographic microscope and scanning electron microscope (SEM). Energy-dispersive spectroscopy (EDS) with SEM provided elements analysis information for the test samples after 10% oxalic acid solution etching test. Tafel polarization curve recordings demonstrated parameter values indicating corrosion of the samples when subjected to electrochemical testing. This study has suggested that massive oxides are attached to the surface of the CoCr–keeper complex but not to the AuPt–keeper complex. Only the keeper area of cast CoCr–keeper complex displayed obvious intergranular corrosion and changes in the Fe and Co elements. Both cast and laser-welded AuPt–keeper complexes had the highest free corrosion potential, followed by the PdAu–keeper complex. We concluded that although the corrosion resistance of the CoCr–keeper complex was worst, the keeper surface passive film was actually preserved to its maximum extent. The laser-welded CoCr– and PdAu–keeper complexes possessed superior corrosion resistance as compared with their cast specimens, but no significant difference was found between the cast and laser-welded AuPt–keeper complexes. The Fe-poor and Cr-rich band, appearing on the edge of the keeper when casting, has been proven to be a corrosion-prone area. PMID:27388806

Cast erosion from the cleaning of debris after the use of a cast trimmer.

PubMed

Hansen, Paul A; Beatty, Mark W

2017-02-01

Whether using tap water to rinse off debris will make a clinical difference to the surface detail of a gypsum cast is unknown. In addition, how best to remove debris from the cast is unknown. The purpose of this in vitro study was to evaluate the efficiency of different methods of cleaning a gypsum cast after trimming and the effect of short-term exposure to tap water on the surface quality of the cast. A die fitting American National Standards Institute/American Dental Association specification 25 (International Standards Organization specification 6873) for dental gypsum products was embedded in a Dentoform with the machined lines positioned at the same level as the occlusal surface of the posterior teeth. A flat plate was used to ensure that the plane of occlusion for the die was at the same position as the posterior teeth. Forty polyvinyl siloxane impressions of the Dentoform were made and poured with vacuum-mixed improved Type IV dental stone. Each cast was inspected for the accurate reproduction of the lines. The base of the 2-stage pour was trimmed with a cast trimmer with water, and surface debris was removed by rinsing by hand under tap water for 10 seconds, by brushing the cast with a soft toothbrush for 10 seconds, or by resoaking the cast and using a soft camel hair brush in slurry water for 10 seconds. The amount of debris was evaluated on a scale of 1 to 4, and the quality of the 20-μm line was evaluated on a scale of 1 to 4 under ×15 magnification. The nonparametric Kruskal-Wallis ranks test was used to identify significant differences among the different cleaning methods (α=.05). Results of the Kruskal-Wallis and Kruskal-Wallis Z-value tests demonstrated that all cleaning methods produced cleaner casts than were observed for uncleansed controls (P<.001), but no differences in debris removal were found among the different cleaning methods (.065≤P≤.901). The ability to see the quality of a 20-μm line (P=.974) was not statistically different among the groups. Rinsing the cast under flowing tap water and brushing, or hand washing under flowing tap water, or using a soft camel hair brush in slurry water for 10 seconds had no noticeable effects on the quality of a 20-μm line, and all 3 methods resulted in a clean cast. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Quantitative Assessment of Antimicrobial Activity of PLGA Films Loaded with 4-Hexylresorcinol

PubMed Central

Kemme, Michael; Heinzel-Wieland, Regina

2018-01-01

Profound screening and evaluation methods for biocide-releasing polymer films are crucial for predicting applicability and therapeutic outcome of these drug delivery systems. For this purpose, we developed an agar overlay assay embedding biopolymer composite films in a seeded microbial lawn. By combining this approach with model-dependent analysis for agar diffusion, antimicrobial potency of the entrapped drug can be calculated in terms of minimum inhibitory concentrations (MICs). Thus, the topical antiseptic 4-hexylresorcinol (4-HR) was incorporated into poly(lactic-co-glycolic acid) (PLGA) films at different loadings up to 3.7 mg/cm2 surface area through a solvent casting technique. The antimicrobial activity of 4-HR released from these composite films was assessed against a panel of Gram-negative and Gram–positive bacteria, yeasts and filamentous fungi by the proposed assay. All the microbial strains tested were susceptible to PLGA-4-HR films with MIC values down to 0.4% (w/w). The presented approach serves as a reliable method in screening and quantifying the antimicrobial activity of polymer composite films. Moreover, 4-HR-loaded PLGA films are a promising biomaterial that may find future application in the biomedical and packaging sector. PMID:29324696

Nuclear organization in human sperm: preliminary evidence for altered sex chromosome centromere position in infertile males.

PubMed

Finch, K A; Fonseka, K G L; Abogrein, A; Ioannou, D; Handyside, A H; Thornhill, A R; Hickson, N; Griffin, D K

2008-06-01

Many genetic defects with a chromosomal basis affect male reproduction via a range of different mechanisms. Chromosome position is a well-known marker of nuclear organization, and alterations in standard patterns can lead to disease phenotypes such as cancer, laminopathies and epilepsy. It has been demonstrated that normal mammalian sperm adopt a pattern with the centromeres aligning towards the nuclear centre. The purpose of this study was to test the hypothesis that altered chromosome position in the sperm head is associated with male infertility. The average nuclear positions of fluorescence in-situ hybridization signals for three centromeric probes (for chromosomes X, Y and 18) were compared in normoozoospermic men and in men with compromised semen parameters. In controls, the centromeres of chromosomes X, Y and 18 all occupied a central nuclear location. In infertile men the sex chromosomes appeared more likely to be distributed in a pattern not distinguishable from a random model. Our findings cast doubt on the reliability of centromeric probes for aneuploidy screening. The analysis of chromosome position in sperm heads should be further investigated for the screening of infertile men.

Full-scale high-speed ``Edgerton'' retroreflective shadowgraphy of gunshots

NASA Astrophysics Data System (ADS)

Settles, Gary

2005-11-01

Almost 1/2 century ago, H. E. ``Doc'' Edgerton demonstrated a simple and elegant direct-shadowgraph technique for imaging large-scale events like explosions and gunshots. Only a retroreflective screen, flashlamp illumination, and an ordinary view camera were required. Retroreflective shadowgraphy has seen occasional use since then, but its unique combination of large scale, simplicity and portability has barely been tapped. It functions well in environments hostile to most optical diagnostics, such as full-scale outdoor daylight ballistics and explosives testing. Here, shadowgrams cast upon a 2.4 m square retroreflective screen are imaged by a Photron Fastcam APX-RS digital camera that is capable of megapixel image resolution at 3000 frames/sec up to 250,000 frames/sec at lower resolution. Microsecond frame exposures are used to examine the external ballistics of several firearms, including a high-powered rifle, an AK-47 submachine gun, and several pistols and revolvers. Muzzle blast phenomena and the mechanism of gunpowder residue deposition on the shooter's hands are clearly visualized. In particular, observing the firing of a pistol with and without a silencer (suppressor) suggests that some of the muzzle blast energy is converted by the silencer into supersonic jet noise.

Genetic polymorphism in leaf-cutting ants is phenotypically plastic.

PubMed

Hughes, William O H; Boomsma, Jacobus J

2007-07-07

Advanced societies owe their success to an efficient division of labour that, in some social insects, is based on specialized worker phenotypes. The system of caste determination in such species is therefore critical. Here, we examine in a leaf-cutting ant (Acromyrmex echinatior) how a recently discovered genetic influence on caste determination interacts with the social environment. By removing most of one phenotype (large workers; LW) from test colonies, we increased the stimulus for larvae to develop into this caste, while for control colonies we removed a representative sample of all workers so that the stimulus was unchanged. We established the relative tendencies of genotypes to develop into LW by genotyping workers before and after the manipulation. In the control colonies, genotypes were similarly represented in the large worker caste before and after worker removal. In the test colonies, however, this relationship was significantly weaker, demonstrating that the change in environmental stimuli had altered the caste propensity of at least some genotypes. The results indicate that the genetic influence on worker caste determination acts via genotypes differing in their response thresholds to environmental cues and can be conceptualized as a set of overlapping reaction norms. A plastic genetic influence on division of labour has thus evolved convergently in two distantly related polyandrous taxa, the leaf-cutting ants and the honeybees, suggesting that it may be a common, potentially adaptive, property of complex, genetically diverse societies.

DE LAVAUD CHARGING FROM WEST (UPHILL), TREATING LANCE WITH CALCIUM ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DE LAVAUD CHARGING FROM WEST (UPHILL), TREATING LANCE WITH CALCIUM CARBONATE IN CENTER & CASTING PIPE TO THE RIGHT. - United States Pipe & Foundry Company Plant, Pipe Casting & Testing Area, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

Microstructure and Mechanical Properties of a Low Alloyed MnB Cast Steel

NASA Astrophysics Data System (ADS)

Luo, Kaishuang; Bai, Bingzhe

2010-08-01

The microstructure and mechanical properties of a low alloyed MnB cast steel designed for coupler castings of trucks were studied. The results show that the microstructure of the MnB cast steel after water quenching is lath martensite and a small amount of massive islands in the matrix of lath martensite. The average size of the martensite packets is about 10 μm in length. Carbides precipitated dispersively at the tempering temperature of 450 °C. The carbides are slender and fibrous, of which the microstructure was θ-phase (Fe, Mn)3C characterized by TEM. The MnB cast steel has good hardenability and tempering stability. Excellent combination of strength, ductility and low-temperature toughness were obtained after water-quenching and 450 °C tempering: Rm = 960-1040 MPa, ReL = 880-900 MPa, A = 19-21%, Z = 56-58%. Especially, the impact energy of the Charpy V-Notch (CVN) specimens reached 70-88 J at -40 °C. The fracture mechanism is transcrystalline fracture both for ambient temperature uniaxial tensile test specimens and for CVN impact test specimens broken at -40 °C, where the whole surfaces were manifested as voids and dimples.

StatsCasts: screencasts for complementing lectures in statistics classes

NASA Astrophysics Data System (ADS)

Dunn, Peter K.; McDonald, Christine; Loch, Birgit

2015-05-01

Students who are studying introductory statistics units but are enrolled in non-statistics majors often struggle with the content, and do not stay engaged. Support structures are in place at many Australian universities to help these students. Most of these are face-to-face support centres that the students can visit during opening hours. To provide additional assistance to these students any time, and from anywhere, online media are increasingly used by students - either provided by support centres, or sought independently by students. Little research has been undertaken on the effectiveness of such resources to support student learning. This paper investigates whether students will embrace StatsCasts - short screen-capture videos on key statistical topics that students have struggled with in the past, with narrator explanation provided by the lecturer - as part of their learning strategy and if they will actively engage with the videos. Students enrolled in a large first-year statistics class at an Australian university who had been provided with StatsCasts responded to a survey at the end of the semester. Volunteering students also participated in a focus group to probe deeper into students' perceptions of and motivations for watching the videos. Analysis of the data shows that students do actively engage with the StatsCasts and they appear to become an important component of their study and revision strategy.

Mechanical strength and microstructure of laser-welded Ti-6Al-7Nb alloy castings.

PubMed

Srimaneepong, Viritpon; Yoneyama, Takayuki; Kobayashi, Equo; Doi, Hisashi; Hanawa, Takao

2005-12-01

Mechanical properties of laser-welded castings of Ti-6Al-7Nb alloy, CP Ti, and Co-Cr alloy were investigated and compared to the unwelded castings using a tensile test. Dumbbell-shaped specimens were cut at the center, and two halves of the specimens were welded with an Nd:YAG laser welding machine at 220 or 260 V of laser voltage. The mechanical strength of 260 V groups was higher than that of 220 V groups for Ti-6Al-7Nb and Co-Cr alloys except for CP Ti. All 260 V laser-welded castings of Ti-6Al-7Nb alloy and CP Ti, which fractured outside the welded joints, exhibited ductile characteristics, while all laser-welded Co-Cr alloy castings, which fractured within the welded joints, showed brittle characteristics. This study proved that the mechanical strength of laser-welded Ti-6Al-7Nb alloy and CP Ti castings was as high as that of unwelded castings, while the mechanical properties of laser-welded alloy joints were influenced by microstructural changes.

Phase-aberration correction with a 3-D ultrasound scanner: feasibility study.

PubMed

Ivancevich, Nikolas M; Dahl, Jeremy J; Trahey, Gregg E; Smith, Stephen W

2006-08-01

We tested the feasibility of using adaptive imaging, namely phase-aberration correction, with two-dimensional (2-D) arrays and real-time, 3-D ultrasound. Because of the high spatial frequency content of aberrators, 2-D arrays, which generally have smaller pitch and thus higher spatial sampling frequency, and 3-D imaging show potential to improve the performance of adaptive imaging. Phase-correction algorithms improve image quality by compensating for tissue-induced errors in beamforming. Using the illustrative example of transcranial ultrasound, we have evaluated our ability to perform adaptive imaging with a real-time, 3-D scanner. We have used a polymer casting of a human temporal bone, root-mean-square (RMS) phase variation of 45.0 ns, full-width-half-maximum (FWHM) correlation length of 3.35 mm, and an electronic aberrator, 100 ns RMS, 3.76 mm correlation, with tissue phantoms as illustrative examples of near-field, phase-screen aberrators. Using the multilag, least-squares, cross-correlation method, we have shown the ability of 3-D adaptive imaging to increase anechoic cyst identification, image brightness, contrast-to-speckle ratio (CSR), and, in 3-D color Doppler experiments, the ability to visualize flow. For a physical aberrator skull casting we saw CSR increase by 13% from 1.01 to 1.14, while the number of detectable cysts increased from 4.3 to 7.7.