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Sample records for bullhead city az

  1. 76 FR 38568 - Safety Zone; Bullhead City Regatta, Bullhead City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-01

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Bullhead City Regatta, Bullhead City, AZ... temporary safety zone on the navigable waters of the Colorado River in Bullhead City, Arizona for the Bullhead City Regatta on August 13, 2011. This temporary safety zone is necessary to provide for the...

  2. 78 FR 34300 - Safety Zone; Bullhead City Regatta, Bullhead City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-07

    ... DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed Rulemaking A. Public... Federal Register (73 FR 3316). 4. Public Meeting We do not now plan to hold a public meeting. But you may... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Bullhead City Regatta, Bullhead City,...

  3. 77 FR 36439 - Safety Zone; Bullhead City Regatta; Bullhead City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-19

    .... SUPPLEMENTARY INFORMATION: Table of Acronyms DHS Department of Homeland Security FR Federal Register NPRM Notice... public dockets in the January 17, 2008, issue of the Federal Register (73 FR 3316). 4. Public Meeting We... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Bullhead City Regatta; Bullhead City,...

  4. 78 FR 71706 - Noise Exposure Map Notice for Laughlin/Bullhead International Airport, Bullhead City, Arizona

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-29

    ... Federal Aviation Administration Noise Exposure Map Notice for Laughlin/Bullhead International Airport... Aviation Administration (FAA) announces its determination that the noise exposure maps submitted by Mohave.... 47501 et seq. (Aviation Safety and Noise Abatement Act) and 14 CFR Part 150 are in compliance...

  5. 78 FR 44011 - Safety Zone; Bullhead City Regatta; Bullhead City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-23

    ... Management Facility in Room W12-140 on the ground floor of the Department of Transportation West Building.... SUPPLEMENTARY INFORMATION: ] Table of Acronyms DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed Rulemaking A. Regulatory History and Information The Coast Guard issued a Notice...

  6. 78 FR 13811 - Special Local Regulation; Annual Marine Events on the Colorado River, Between Davis Dam (Bullhead...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 100 Special Local Regulation; Annual Marine Events on the Colorado River, Between Davis Dam (Bullhead City, AZ) and Headgate Dam (Parker, AZ) Within the San Diego Captain of...

  7. 77 FR 70121 - Special Local Regulation; Annual Marine Events on the Colorado River Between Davis Dam (Bullhead...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-23

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 100 Special Local Regulation; Annual Marine Events on the Colorado River Between Davis Dam (Bullhead City, AZ) and Headgate Dam (Parker, AZ) Within the San Diego Captain of...

  8. 77 FR 67563 - Special Local Regulation; Annual Marine Events on the Colorado River, Between Davis Dam (Bullhead...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 100 Special Local Regulation; Annual Marine Events on the Colorado River, Between Davis Dam (Bullhead City, AZ) and Headgate Dam (Parker, AZ) Within the San Diego Captain of...

  9. 33 CFR 165.1124 - Annual Firework Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Annual Firework Events on the... § 165.1124 Annual Firework Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and... § 165.1124 1. Avi Resort & Casino Memorial Day Fireworks Sponsor Avi Resort & Casino. Event...

  10. 33 CFR 165.1124 - Annual Firework Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Annual Firework Events on the... § 165.1124 Annual Firework Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and... § 165.1124 1. Avi Resort & Casino Memorial Day Fireworks Sponsor Avi Resort & Casino. Event...

  11. 33 CFR 165.1124 - Annual Firework Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Annual Firework Events on the... § 165.1124 Annual Firework Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and... § 165.1124 1. Avi Resort & Casino Memorial Day Fireworks Sponsor Avi Resort & Casino. Event...

  12. 78 FR 48303 - Establishment of Class E Airspace; Tuba City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-08

    ... Tuba City VORTAC, Tuba City, AZ (78 FR 32086, May 29, 2013). In the regulatory text, the region... TRANSPORTATION Federal Aviation Administration 14 CFR Parts 71 Establishment of Class E Airspace; Tuba City, AZ..., 2013 (78 FR 32086), Airspace Docket No. 13-AWP-1, FR Doc. 2013-12623, is corrected as follows: Sec....

  13. 78 FR 17097 - Safety Zone; Lake Havasu Triathlon; Lake Havasu City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Havasu Triathlon; Lake Havasu City, AZ... temporary safety zone within the navigable waters of Lake Havasu and the London Bridge Channel for the Lake... Triathlon will consist of 600 participants. The waterside swim course consists of 1500 meters in Lake...

  14. 78 FR 32086 - Establishment of Class E Airspace; Tuba City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-29

    ... rulemaking (NPRM) to amend controlled airspace at Tuba City, AZ (78 FR 16823). Interested parties were... 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The...

  15. 78 FR 16823 - Proposed Establishment of Class E Airspace; Tuba City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-19

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does... FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in 14 CFR 71.1... (IFR) aircraft under control of Denver, Albuquerque and Salt Lake City Air Route Traffic...

  16. Habitat Suitability Index Models: Black Bullhead

    USGS Publications Warehouse

    Stuber, Robert J.

    1982-01-01

    This is one of a series of publications that provide information on the habitat requirements of selected fish and wildlife species. Literature describing the relationship between habitat variables related to life requisites and habitat suitability for the Black bullhead (Ictalurus melas) are synthesized. These data are subsequently used to develop Habitat Suitability (HIS) models. The HSI models are designed to provide information that can be used in impact assessment and habitat management.

  17. Phoenix, AZ, USA

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The city of Phoenix, AZ (33.5N, 112.0W) can be seen in good detail in this color infrared scene. Situated among truck crop agriculture fields, the color infrared photo depicts the vegetated fields as shades of red making the agriculture stand out in this desert environment. To the east, Lake Theodore Roosevelt and dam can be easily seen.

  18. 78 FR 60698 - Safety Zone, Lucas Oil Drag Boat Racing Series; Thompson Bay, Lake Havasu City, AZ.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-02

    .... SUPPLEMENTARY INFORMATION: Table of Acronyms DHS Department of Homeland Security FR Federal Register NPRM Notice... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone, Lucas Oil Drag Boat Racing Series; Thompson..., AZ for the Lucas Oil Drag Boat Racing Series. This temporary safety zone is necessary to...

  19. HISTORICAL MONITORING OF BIOMARKERS OF EXPOSURE OF BROWN BULLHEAD

    EPA Science Inventory

    Biomarkers of exposure to chemical contamination, benzo(a)pyrene (BAP) and naphthalene (NAPH) type metabolites were measured in brown bullhead from a heavily polycyclic aromatic hydrocarbon (PAH) contaminated section of the Black River, Ohio during and immediately after remedial ...

  20. DNA DAMAGE AND EXTERNAL LESIONS IN BROWN BULLHEAD FROM CONTAMINATED HABITATS

    EPA Science Inventory

    The single cell gel electrophoresis ("Comet") assay was used to compare levels of DNA damage in brown bullheads (Ameiurus nebulosus) collected from three known contaminated locations, the Cuyahoga River, Ashtabula River, and Ashumet Pond (Cape Cod), with brown bullheads collected...

  1. Biotic and abiotic correlates with black bullhead population characteristics in Nebraska sandhill lakes

    USGS Publications Warehouse

    Phelps, Q.E.; Ward, M.J.; Paukert, C.P.; Chipps, S.R.; Willis, D.W.

    2005-01-01

    We explored relationships among black bullhead (Ameiurus melas) population characteristics and physicochemical attributes in shallow lakes and quantified relationships between population characteristics of black bullhead and sport fishes. Lake characteristics and fisheries survey data were collected from the Sandhills region of northcentral Nebraska from May through June, 1998 and 1999. Relative abundance of black bullheads was inversely related to proportional stock density (r=-0.672, df=15, P=0.004); however, neither relative weight nor growth was significantly (P ??? 0.20) related to black bullhead relative abundance. Population characteristics of common panfish species such as bluegill (Lepomis macrochirus), green sunfish (L. cyanellus), pumpkinseed (L. gibbosus), and yellow perch (Perca flavescens) were not correlated with black bullhead relative abundance or size structure. Rather, proportional stock density (r=0.655, df=10, P=0.029) and growth (r=0.59, df=11, P=0.04) of black bullhead were positively related to relative abundance of largemouth bass (Micropterus salmoides). Similarly, black bullhead relative abundance was inversely related to largemouth bass size structure (r=-0.51, df=14, P= 0.05). Black bullhead mean length at age 3 was positively related to total phosphorous concentration (r=0.65, df=16, P=0.004), and bullhead relative abundance was positively related to shoreline development index (r=0.46, df=22, P=0.03). Population characteristics of black bullhead appeared to have little influence on panfish communities. Rather, black bullhead abundance, predator density, and lake productivity exhibited stronger relationships with black bullhead population characteristics.

  2. DNA DAMAGE AND EXTERNAL LESIONS IN BROWN BULLHEADS FROM CONTAMINATED HABITATS

    EPA Science Inventory

    The Comet assay was used to compare levels of DNA damage in brown bullheads (Ameiurus nebulosus) collected from three known contaminated locations, the Cuyahoga River, Ashtabula River, and Ashumet Pond (Cape Cod), with brown bullheads collected from three paired reference sites, ...

  3. SERUM CHEMISTRY AND HISTOPATHOLOGICAL EVALUATIONS OF BROWN BULLHEADS (AMEIURUS NEBULOSUS) FROM THE BUFFALO AND NIAGARA RIVERS

    EPA Science Inventory

    Cholangiomas and cholangiocarcinomas were observed in brown bullheads (Ameiurus nebulosus) collected from the Buffalo and Niagara Rivers (NY) and Old Woman Creek (OH). ignificant increases in serum BUN, uric acid, triglycerides inorganic phosphate, ALT, LDL, calcium and iron and ...

  4. PATHOLOGICAL AND SERUM CHEMISTRY PROFILES OF BROWN BULLHEADS (AMERIURUS NEBULOSUS) FROM THE BLACK RIVER AND OLD WOMAN CREEK, OHIO

    EPA Science Inventory

    This study compares serum chemistry values for brown bullheads (Amciurus nebulosus) from the industrially contaminated Black River, Ohio, with the rural and relatively uncontaminated Old Woman Creek, Ohio. ifty-two percent (24 of 46) brown bullheads over 3-years-old had liver neo...

  5. In vitro kinetics of hepatic glutathione s-transferase conjugation in largemouth bass and brown bullheads

    SciTech Connect

    Gallagher, E.P.; Sheehy, K.M.; Lame, M.W.; Segall, H.J.

    2000-02-01

    The kinetics of glutathione 5-transferase (GST) catalysis were investigated in largemouth bass (Micropterus salmoides) and brown bullheads (Amerius nebulosus), two freshwater fish species found in a variety of polluted waterways in the eastern US. The initial rates of hepatic GST activity toward four GST substrates, including 1-chloro-2,4-dinitrobenzene, ethacrynic acid, {Delta}5-androstene-17-dione, and nitrobutyl chloride, were significantly higher in brown bullheads than in largemouth bass. Hepatic GST activity toward 1,2-dichloro-4-nitrobenzene, a {mu}-class GST substrate in rodents, was not detectable in either species. Liver cytosolic GSTs were more efficient in bullheads than in bass at catalyzing 1-chloro-2,4-dinitrobenzene-reduced glutathione (CDNB-GSH) conjugation over a broad range of electrophile (CDNB) concentrations, including those representative of environmental exposure. In contrast, largemouth bass maintained higher ambient concentrations of GSH, the nucleophilic cofactor for GST-mediated conjugation, than brown bullheads. Biphasic kinetics for GST-CDNB conjugation under conditions of variable GSH concentration were apparent in Eadie-Hofstee plots of the kinetic data, suggesting the presence of at least two hepatic GST isozymes with markedly different K{sub m} values for GSH in both species. The GST-CDNB reaction rate data obtained under conditions of variable GSH were well fitted (R{sup 2} = 0.999) by the two-enzyme Michaelis-Menten equation. In addition, Western blotting experiments confirmed the presence of two different hepatic GST-like proteins in both largemouth bass and brown bullhead liver. Collectively, these findings indicate that largemouth bass and brown bullhead GSTs catalyze the conjugation of structurally diverse, class-specific GST substrates, and that brown bullheads exhibit higher initial rates of GST activity than largemouth bass. The relatively higher rates of in vitro liver GST activity at the low substrate concentrations relevant to environmental exposure is expected to protect brown bullheads from the toxic effects of sediment-associated electrophilic chemicals. The somewhat lower rates of GST activity in largemouth bass liver compared with brown bullhead liver, however, may be offset by maintenance of higher ambient hepatic GSH concentrations in largemouth bass.

  6. Decreased glutathione S-transferase expression and activity and altered sex steroids in Lake Apopka brown bullheads (Ameriurus nebulosus)

    USGS Publications Warehouse

    Gallagher, E.P.; Gross, T.S.; Sheehy, K.M.

    2001-01-01

    A number of freshwater lakes and reclaimed agricultural sites in Central Florida have been the receiving waters for agrochemical and municipal runoff. One of these sites, Lake Apopka, is also a eutrophic system that has been the focus of several case studies reporting altered reproductive activity linked to bioaccumulation of persistent organochlorine chemicals in aquatic species. The present study was initiated to determine if brown bullheads (Ameriurus nebulosus) from the north marsh of Lake Apopka (Lake Apopka Marsh) exhibit an altered capacity to detoxify environmental chemicals through hepatic glutathione S-transferase (GST)-mediated conjugation as compared with bullheads from a nearby reference site (Lake Woodruff). We also compared plasma sex hormone concentrations (testosterone, 17-?? estradiol, and 11 keto-testosterone) in bullheads from the two sites. Female bullheads from Lake Apopka had 40% lower initial rate GST conjugative activity toward 1-chloro-2,4-dinitrobenzene (CDNB), 50% lower activity towards p-nitrobutyl chloride (NBC), 33% lower activity toward ethacrynic acid (ECA), and 43% lower activity toward ??5-androstene-3,17-dione (??5-ADI), as compared with female bullheads from Lake Woodruff. Enzyme kinetic analyses demonstrated that female bullheads from Lake Apopka had lower GST-catalyzed CDNB clearance than did female Lake Woodruff bullheads. Western blotting studies of bullhead liver cytosolic proteins demonstrated that the reduced GST catalytic activities in female Lake Apopka bullheads were accompanied by lower expression of hepatic GST protein. No site differences were observed with respect to GST activities or GST protein expression in male bullheads. Female Lake Apopka bullheads also had elevated concentrations of plasma androgens (testosterone and 11-ketotestosterone) as compared with females from Lake Woodruff. In contrast, male Lake Apopka bullheads had elevated levels of plasma estrogen but similar levels of androgens as compared with male bullheads from Lake Woodruff. Collectively, our studies indicate the presence of reduced GST protein expression, reduced GST conjugative capacity and altered sex steroid homeostasis in female bullheads from a contaminated field site in Central Florida. The implications of these physiological alterations in terms of pollutant biotransformation and reproduction are discussed. ?? 2001 Elsevier Science B.V. All rights reserved.

  7. Biomarkers of exposure of brown bullheads to contaminants in the lower Great Lakes

    SciTech Connect

    Arcand, L.D.; Metcalfe, C.D.

    1995-12-31

    Brown bullheads (Ameiurus nebulosus) were collected from contaminated and relatively pristine sites distributed throughout Lake Erie and Lake Ontario. Hepatic neoplasms were detected in bullheads from the contaminated sites of Hamilton Harbour (L. Ontario), the Black River (L. Erie) and the Detroit River, but no tumors were observed in bullheads from the relatively pristine Bay of Quinte (L. Ontario) and Old Woman Creek (L. Erie). Analysis of various biochemical markers of exposure to contaminants indicated that bullheads from the contaminated sites had elevated hepatic EROD activity, high levels of fluorescent aromatic compounds (FACS) in bile, and alterations to hepatic retinoid levels. Bullheads captured in the Black River also had an increased incidence of micronucleated hepatocytes in comparison to fish from Old Woman Creek. Although the prevalence of hepatic neoplasms was highest in Detroit River fish, all biomarkers did not necessarily indicate that Detroit River fish were the most highly exposed to contaminants. These data indicate that a suite of several biomarkers should be used to monitor for in situ exposure of fish to contaminants.

  8. Prevalence of Tumors in Brown Bullhead from Three Lakes in Southeastern Massachusetts, 2002

    USGS Publications Warehouse

    Baumann, Paul C.; LeBlanc, Denis R.; Blazer, Vicki; Meier, John R.; Hurley, Stephen T.; Kiryu, Yasu

    2008-01-01

    The Massachusetts Military Reservation (MMR) has been a military base on western Cape Cod since the early 1900s. Contaminated surface water and ground water from the MMR have discharged into several kettle lakes on or near the base. To discover whether the prevalences of tumors and other lesions in brown bullhead (Ameiurus nebulosus) in these lakes, particularly Ashumet Pond, were elevated above normal, the U.S. Geological Survey (USGS), assisted by the U.S. Environmental Protection Agency (USEPA) and the Massachusetts Division of Fisheries and Wildlife (MADFW), conducted a study in 2002 of brown bullhead in Ashumet Pond and in two reference lakes, Santuit Pond (on Cape Cod) and Great Herring Pond (on the mainland of Massachusetts). Brown bullhead from Great Herring Pond had few external raised lesions (2.8 percent), a low prevalence of liver neoplasms (5 percent), and little genetic damage to their red blood cell nuclei. Brown bullhead from Ashumet Pond had a high prevalence of raised lesions (62.1 percent), which included histopathologically verified papillomas and squamous carcinoma; an elevated incidence of liver neoplasms (16.7 percent); and an elevated level of genetic damage to their red blood cell nuclei. Because red blood cells in fish have a lifespan of about 100 days, these results indicate an ongoing exposure to genotoxins in Ashumet Pond. Brown bullhead from Santuit Pond also had elevated prevalences of raised lesions (48.3 percent) and liver neoplasms (15 percent), although the prevalences of large and multiple lesions were significantly lower than those in fish from Ashumet Pond. These differences may indicate differing causes of pathology in the two lakes. The high prevalence of melanistic lesions on brown bullhead from Ashumet Pond, combined with the tumor pathology and genetic damage, implicates chemical carcinogens as one of the causal factors in that lake.

  9. Diagnostic criteria for proliferative hepatic lesions in brown bullhead Ameiurus nebulosus

    USGS Publications Warehouse

    Blazer, V.S.; Fournie, J.W.; Wolf, J.C.; Wolfe, M.J.

    2006-01-01

    Brown bullhead Ameiurus nebulosus is used as indicator species for contaminant effects at areas of concern (AOC) in the Great Lakes and other areas. One of the beneficial use impairments at numerous AOC is 'fish tumors and other deformities'. An impairment occurs when the prevalence of fish tumors and other deformities exceeds those at unimpacted or control sites or when survey data confirm the presence of neoplastic or preneoplastic liver lesions in bullhead or white sucker Catostomus commersonii. Numerous surveys have been conducted over the years assessing neoplasia in these fishes, both liver and skin tumors. However, a major problem in comparing the results has been a lack of consistent criteria for evaluating histological changes in bullhead livers. As individual AOC develop and implement remedial action plans, realistic and attainable delisting targets need to be specified. For this to occur and be consistent from site to site there must be standardization of the criteria being used to evaluate specific impairments. In this report, specific diagnostic criteria are provided for both non-neoplastic and neoplastic proliferative hepatocellular and biliary lesions. These criteria should assist fish pathologists in describing and categorizing proliferative liver lesions from brown bullhead. ?? Inter-Research 2006.

  10. SYNCHRONOUS FLUOROMETRIC MEASUREMENT OF METABOLITES OF POLYCYCLIC AROMATIC HYDROCARBONS IN THE BILE OF BROWN BULLHEAD

    EPA Science Inventory

    A synchronous fluorescent spectroscopy (SFS) method was developed to measure pyrene-type metabolites in the bile of brown bullhead (Ameiurus nebulosus) and to estimate the exposure of fish to PAHs in four Lake Erie tributaries collected in the spring and fall of 1990 and 1991. Fo...

  11. Tumor prevalence and biomarkers of genotoxicity in brown bullhead (Ameiurus nebulosus) in Chesapeake Bay tributaries

    USGS Publications Warehouse

    Pinkney, Alfred E.; Harshbarger, John C.; Karouna-Renier, Natalie K.; Jenko, Kathryn; Balk, Lennart; Skarphinsdttir, Halldora; Liewenborg, Birgitta; Rutter, Michael A.

    2011-01-01

    We surveyed four Chesapeake Bay tributaries for skin and liver tumors in brown bullhead (Ameiurus nebulosus). We focused on the South River, where the highest skin tumor prevalence (53%) in the Bay watershed had been reported. The objectives were to 1) compare tumor prevalence with nearby rivers (Severn and Rhode) and a more remote river (Choptank); 2) investigate associations between tumor prevalence and polynuclear aromatic hydrocarbons (PAHs) and alkylating agents; and 3) statistically analyze Chesapeake Bay bullhead tumor data from 1992 through 2008. All four South River collections exhibited high skin tumor prevalence (19% to 58%), whereas skin tumor prevalence was 2%, 10%, and 52% in the three Severn collections; 0% and 2% in the Choptank collections; and 5.6% in the Rhode collection. Liver tumor prevalence was 0% to 6% in all but one South River collection (20%) and 0% to 6% in the three other rivers. In a subset of samples, PAH-like biliary metabolites and 32P-DNA adducts were used as biomarkers of exposure and response to polycyclic aromatic compounds (PACs). Adducts from alkylating agents were detected as O6-methyl-2'-deoxyguanosine (O6Me-dG) and O6-ethyl-2'-deoxyguanosine (O6Et-dG) modified DNA. Bullheads from the contaminated Anacostia River were used as a positive control for DNA adducts. 32P-DNA adduct concentrations were significantly higher in Anacostia bullhead livers compared with the other rivers. We identified alkyl DNA adducts in bullhead livers from the South and Anacostia, but not the Choptank. Neither the PAH-like bile metabolite data, sediment PAH data, nor the DNA adduct data suggest an association between liver or skin tumor prevalence and exposure to PACs or alkylating agents in the South, Choptank, Severn, or Rhode rivers. Logistic regression analysis of the Chesapeake Bay database revealed that sex and length were significant covariates for liver tumors and length was a significant covariate for skin tumors.

  12. Tumor prevalence and biomarkers of genotoxicity in brown bullhead (Ameiurus nebulosus) in Chesapeake Bay tributaries

    USGS Publications Warehouse

    Pinkney, A.E.; Harshbarger, J.C.; Karouna-Renier, N. K.; Jenko, K.; Balk, L.; Skarpheinsdottir, H.; Liewenborg, B.; Rutter, M.A.

    2011-01-01

    We surveyed four Chesapeake Bay tributaries for skin and liver tumors in brown bullhead (Ameiurus nebulosus). We focused on the South River, where the highest skin tumor prevalence (53%) in the Bay watershed had been reported. The objectives were to 1) compare tumor prevalence with nearby rivers (Severn and Rhode) and a more remote river (Choptank); 2) investigate associations between tumor prevalence and polynuclear aromatic hydrocarbons (PAHs) and alkylating agents; and 3) statistically analyze Chesapeake Bay bullhead tumor data from 1992 through 2008. All four South River collections exhibited high skin tumor prevalence (19% to 58%), whereas skin tumor prevalence was 2%, 10%, and 52% in the three Severn collections; 0% and 2% in the Choptank collections; and 5.6% in the Rhode collection. Liver tumor prevalence was 0% to 6% in all but one South River collection (20%) and 0% to 6% in the three other rivers. In a subset of samples, PAH-like biliary metabolites and 32P-DNA adducts were used as biomarkers of exposure and response to polycyclic aromatic compounds (PACs). Adducts from alkylating agents were detected as O6-methyl-2'-deoxyguanosine (O6Me-dG) and O6-ethyl-2'-deoxyguanosine (O6Et-dG) modified DNA. Bullheads from the contaminated Anacostia River were used as a positive control for DNA adducts. 32P-DNA adduct concentrations were significantly higher in Anacostia bullhead livers compared with the other rivers. We identified alkyl DNA adducts in bullhead livers from the South and Anacostia, but not the Choptank. Neither the PAH-like bile metabolite data, sediment PAH data, nor the DNA adduct data suggest an association between liver or skin tumor prevalence and exposure to PACs or alkylating agents in the South, Choptank, Severn, or Rhode rivers. Logistic regression analysis of the Chesapeake Bay database revealed that sex and length were significant covariates for liver tumors and length was a significant covariate for skin tumors. ?? 2011.

  13. SERUM CHEMISTRY AND HISTOPATHOLOGICAL EVALUATIONS OF BROWN BULLHEADS (AMEIRUS NEBULOSUS) FROM THE BUFFALO AND NIAGARA RIVERS, NEW YORK

    EPA Science Inventory

    Cholangiomas and cholangiocarcinomas were observed in brown bullheads (Ameiurus nebulosus) collected from the Buffalo and Niagara Rivers (NY) and Old Woman Creek (OH), USA. ignificant increases in serum blood urea nitrogen, uric acid, triglycerides, inorganic phosphate, ALT, LDL,...

  14. Chemical accumulation and toxicological stress in three brown bullhead (Ameriurus nebulosus) populations of the Detroit River, Michigan, USA

    SciTech Connect

    Leadley, T.A.; Lazar, R.; Mazak, E.; Habowsky, J.; Haffner, G.D.; Balch, G.; Metcalfe, C.D.

    1998-09-01

    Three populations of brown bullheads (Ameiurus nebulosus) were sampled in the Detroit River and analyzed for concentrations of persistent organic contaminants as well as incidences of external lesions and liver histopathology. Chemical analysis revealed that both the sediments and the bullheads of the Trenton Channel had the highest concentrations of organochlorine compounds, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons compared with the other two sites (Amherstburg Channel and Peche Island). Furthermore, the Trenton Channel bullhead population had a higher prevalence of external abnormalities such as lip and skin lesions as well as truncated barbels. Histopathological analysis of the livers revealed higher prevalences of cholangiocarcinomas, cholangiomas, and other lesions in the Trenton Channel population. These observations support the conclusion that the health of the Trenton Channel bullhead population in the Detroit River is affected by exposure to organic chemicals, primarily through exposure to contaminated sediments.

  15. Biomarkers of exposure of brown bullheads (Ameiurus nebulosus) to contaminants in the lower Great Lakes, North America

    SciTech Connect

    Arcand-Hoy, L.D.; Metcalfe, C.D.

    1999-04-01

    Brown bullheads (Ameiurus nebulosus) from three contaminated sites (Detroit River, Hamilton Harbour, and Black River) and two relatively clean reference sites (Old Woman Creek and Bay of Quinte) in the lower Great Lakes were monitored for several biomarkers of exposure to PAHs. Bullheads from the contaminated sites had elevated hepatosomatic indices, increased ethoxyresorufin-O-deethylase (EROD) activity, decreased hepatic retinoid stores, and a greater incidence of hepatic neoplasms. Fluorescent aromatic compounds (FACs) in the bile were also elevated in bullheads from the Black River and Hamilton Harbour in comparison to fish from reference sites. A correlation was found between reduction of hepatic retinoid stores and induction of hepatic EROD activity in bullheads. Principal component analysis of biomarker data demonstrated that biomarker patterns in Detroit River bullheads were different from those of Black River and Hamilton Harbour bullheads. Biomarkers in fish are useful monitoring tools for detecting contamination of the aquatic environment, but interpretation of results is limited by within- and between-site variability in the responses, some of which may be explained by mobility of the fish. In contaminated areas, bile fluorescent aromatic compounds appear to be the best indicator of recent exposure to polynuclear aromatic hydrocarbons, whereas responses to other biochemical biomarkers appear to be over a longer time period.

  16. DNA damage and external lesions in brown bullheads (Ameiurus nebulosus) from contaminated habitats

    USGS Publications Warehouse

    Yang, X.; Meier, J.; Chang, L.; Rowan, M.; Baumann, P.C.

    2006-01-01

    The Comet assay was used to compare levels of DNA damage in brown bullheads (Ameiurus nebulosus) collected from three known contaminated locations, the Cuyahoga River (OH, USA), Ashtabula River (OH, USA; both tributaries to Lake Erie, USA), and Ashumet Pond (Cape Cod, MA, USA), with brown bullheads collected from three paired reference sites, Old Woman Creek (OH, USA), Conneaut River (OH, USA; both tributaries to Lake Erie), and Great Herring Pond (mainland MA, USA), respectively. Blood was sampled from each fish, and the Comet assay was conducted on erythrocytes. The assay results demonstrate that fish from the three contaminated sites each suffered higher DNA damage compared with fish from their respective reference sites. The results also show that the genetic damage was associated with the occurrence of external lesions and deformities in fish. The Comet assay is sufficiently sensitive to detect exposure of natural fish populations to environmental levels of genotoxic contaminants. ?? 2006 SETAC.

  17. Effect of remedial dredging on bullhead tumor frequency in a recovering river

    SciTech Connect

    Baumann, P.

    1995-12-31

    In 1980 and 1981 high tumor frequencies in brown bullhead from the Black River, Ohio were correlated with high concentrations of polynuclear aromatic hydrocarbons (PAH) in sediment. Surficial sediment levels of PAH dropped after a decline in the steel industry in 1982 followed by closure of the USX coke plant in 1983. By 1987 PAH concentrations had declined to less than one-hundredth of those found in 1980. During this same period liver cancer in age 3+ brown bullhead (Ameiurus nebulosus) underwent a significant decline to about one quarter of the 1982 frequency (38.5%) by 1987 (10%). Then in mid to late 1990, in a delayed reaction to a US EPA consent decree, PAH contaminated sediments were dredged from the river. Surveys in 1992 and 1993 revealed that the cancer frequency in age 3+ brown bullhead had increased to more than 45%. Preliminary 1994 data indicates a decline in grossly observable liver tumors (usually diagnosed as biliary cancers), along with declines in external tumors and eye pathology. The data fit the following hypothesis: Contaminated sediments become less bioavailable with time after a point source is removed, possibly due to deposition of cleaner sediment. Dredging temporarily restores bioavailability (and consequent effects). These data support the position that in some locations controlling contaminants in situ may be preferable to dredging on a cost-benefit basis.

  18. Tumor prevalence and biomarkers in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River watershed [poster

    USGS Publications Warehouse

    Mitchell, R.T.

    2000-01-01

    Associations between contaminant exposure and liver and skin tumor prevalence were evaluated in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River watershed. Thirty bullheads (>260 mm) were collected from (1) Quantico embayment, near a Superfund site which released organochlorine contaminants; (2) Neabsco Creek, a tributary with petroleum inputs from runoff and marinas; and (3) Anacostia River (spring and fall), an urban tributary designated as a Chesapeake Bay Region of Concern, contaminated with PCBs, PAHs, and organochlorine pesticides. Fish were collected from the Tuckahoe River, as a reference. Cytochrome P450 activity, bile PAH metabolites, and muscle organochlorine pesticide/PCB concentrations were measured in randomly-selected individuals and sediment contaminants were analyzed. We found statistically significant differences in liver tumor prevalences: Anacostia (spring)-50%, Anacostia (fall)-60%, Neabsco-17%, Quantico-7%, Tuckahoe-10%. Skin tumor prevalences were significantly different: Anacostia (spring)-37%, Anacostia (fall)-10%, Neabsco-3%, Quantico-3%, Tuckahoe-0%. Tumor prevalence in Anacostia bullheads warrants concern and was similar to those at highly contaminated sites in the Great Lakes. There was evidence of higher PAH exposure in Anacostia fish but a cause-effect linkage cannot be established. Fish tumor surveys, with histopathological examination of internal and external organs, are recommended for monitoring the status of Regions of Concern.

  19. Temperament in bullheads: do laboratory and field explorative behaviour variables correlate?

    NASA Astrophysics Data System (ADS)

    Kobler, Alexander; Engelen, Brecht; Knaepkens, Guy; Eens, Marcel

    2009-10-01

    The relevance of temperament traits for life history strategy or productivity is increasingly acknowledged. Temperament traits are often either observed in captivity or in the wild, but studies combining both observations are very rare. We examine whether exploratory behaviour in the bullhead ( Cottus perifretum), assayed under laboratory conditions, predicts this behaviour under field conditions. Forty-three PIT-tagged individuals were first assayed for exploration of a novel environment in the aquarium and then released into an unfamiliar stream stretch, where they were later relocated using a mobile antenna. Explorative behaviour assayed in the laboratory was significantly positively related to the exploration in the field, thus predicting distance moved in the field release. Both in the laboratory and in the field, explorative behaviour was not related to individual body length. When bullheads that did not leave the refuge in the aquarium (laboratory assay) and, therefore, did not explore the new environment were excluded from the analysis, the correlation between laboratory and field explorative behaviour variables became weaker. However, overall, our results illustrate that exploration rate of bullheads in isolated single-individual experiments can be used to predict this behaviour in the natural ecosystem.

  20. Movements of brown bullheads in Presque Isle Bay, Lake Erie, Pennsylvania

    USGS Publications Warehouse

    Millard, M.J.; Smith, D.R.; Obert, E.; Grazio, J.; Bartron, M.L.; Wellington, C.; Grise, S.; Rafferty, S.; Wellington, R.; Julian, S.

    2009-01-01

    Presque Isle Bay, Lake Erie, was listed as an Area of Concern (AOC) by the International Joint Commission in part because of the high incidence of external tumor in brown bullheads. Verifying the source of the possible contaminant exposure is critical to addressing the AOC designation. We used telemetry tracking (n = 49 fish) to test the hypothesis that adult bullheads captured within the bay during spawning season do not exit the bay during the post-spawning summer and fall months. We analyzed genetic variation at 15 microsatellite loci for 112 adult fish from 5 locations, 4 inside the bay and 1 outside, in order to test for possible differences. Data from fixed-station receivers suggested fish did not leave Presque Isle Bay during the study period. Predicted locations outside Presque Isle Bay were only 0.1% of all predicted locations and were below the 0.2% error rate based on known manual relocations. However, there was evidence for movement within Presque Isle Bay. Most movement was between Misery Bay or Lagoons and the open bay area. Whereas telemetry results showed tendency for adult site fidelity, genetic results showed no differences among locations, indicating that there is a single panmictic population. Our telemetry data suggest that brown bullheads are likely a useful indicator species for environmental conditions in Presque Isle Bay, since adults likely are retained in the system.

  1. Tumor frequencies in walleye (Stizostedion vitreum) and brown bullhead (Ictalurus nebulosus) and sediment contaminants in tributaries of the Laurentian Great Lakes

    USGS Publications Warehouse

    Baumann, Paul C.; Mac, Michael J.; Smith, Stephen B.; Harshbarger, John C.

    1991-01-01

    To better characterize neoplasm epizootics in the Great Lakes basin and their association with families of contaminants, we samples five locations: the Fox and Menominee rivers, Lake Michigan; Munuscong Lake, St. Marys River; and the Black and Cuyahoga rivers, Lake Erie. Frequencies of external and liver tumors were determined for brown bullhead (Ictalurus nebulosus) from all locations except the Black River and for walleye (Stizostedion vitreum) from the Lake Michigan and St. Mary's River sites. Sediment samples were analyzed for metals, polychlorinated aromatics, and polynuclear aromatic hydrocarbons (PAH). Liver neoplasms occurred in brown bullhead from the Cuyahoga River and Munuscong Lake; brown bullhead captured from Munuscong Lake were older than those collected from the other locations. Brown bullhead from these same two rivers had elevated hepatosomatic indexes. No liver neoplasms were found in brown bullhead from the Fox and Menominee rivers, although polychlorinated aromatics were highest in both Fox River sediment and Fox and Menominee brown bullhead, and arsenic was highest in Menominee River sediment and fish. Liver neoplasms in brown bullhead from the Cuyahoga River fit the prevailing hypothesis that elevated PAH in sediment can induce cancer in wild fish. The cause of the liver neoplasms in Munuscong Lake brown bullhead is undetermined.

  2. Mortality and pathology in brown bullheads Amieurus nebulosus associated with a spontaneous Edwardsiella ictaluri outbreak under tank culture conditions

    USGS Publications Warehouse

    Iwanowicz, L.R.; Griffin, A.R.; Cartwright, Deborah D.; Blazer, V.S.

    2006-01-01

    Brown bullheads Amieurus nebulosus (family Ictaluridae) are commonly used as a sentinel of environmental contamination. These fish are not generally cultured under laboratory conditions and little is known about their disease susceptibility. Here we report an outbreak of disease due to Edwardsiella ictaluri in a laboratory population of tank-reared, wild-caught brown bullheads. The isolate was positively identified as E. ictaluri using standard bacteriological substrate utilization tests and a monoclonal antibody specific for this bacterium. This pathogen causes a significant disease in channel catfish Ictalurus punctatus and is associated with disease in other ictalurid and non-ictalurid fishes. It appears that E. ictaluri is also a significant pathogen in brown bullheads and produces clinical signs and lesions similar but not identical to those observed in channel catfish. Since commercial sources of bullheads for laboratory tank studies are not available, precautions should be taken to prevent potential E. ictaluri disease outbreaks from wild-caught bullheads intended for laboratory research. ?? Inter-Research 2006.

  3. Polybrominated diphenyl ethers and their methoxylated and hydroxylated analogs in Brown Bullhead (Ameiurus nebulosus) plasma from Lake Ontario.

    PubMed

    De la Torre, A; Pacepavicius, G; Martínez, M A; Darling, C; Muir, D; Sherry, J; McMaster, M; Alaee, M

    2013-02-01

    Polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs) and hydroxylated PBDEs (OH-PBDEs) were detected and quantified in Brown Bullhead (Ameiurus nebulosus) from Lake Ontario. Samples were collected in 2006 from three different locations near the city of Toronto: Frenchman's Bay, Toronto Island, and Tommy Thompson Park. A total of 117 plasma samples were pooled into 19 samples, separating males and females by site of capture. Pooled samples were analyzed for 36 PBDEs, 20 MeO-PBDEs and 20 OH-PBDEs, but only six PBDEs, five MeO- and eight OH-compounds were confirmed against standards currently available. These peaks were quantified as "identified" peaks, while peaks matching ion ratios but not matching the retention time of the available standards were quantified as "unidentified" peaks. Both "identified" and "unidentified" concentrations were combined to obtain a total concentration. No significant variations were obtained for total PBDE concentrations, ranging from 3.33 to 9.02 ng g(-1)wet weight. However, OH- and MeO-PBDE totals ranged over 1 order of magnitude among the samples (not detected - 3.57 ng g(-1)wet weight for OH-PBDEs and not detected -0.10 ng/g wet weight for MeO-PBDE). The results of this study suggested that these compounds are ubiquitous in biota. Source estimation of MeO- and OH-PBDEs in freshwater fish were discussed. Considering that up to date no freshwater sources for MeO- or OH-PBDEs have been reported, concentrations found should be mainly related to bioaccumulation from anthropogenic sources, although other sources could not be dismissed. PMID:23121987

  4. 76 FR 23787 - Voluntary Termination of Foreign-Trade Subzone 75D, STMicroelectronics, Inc., Phoenix, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-28

    ..., 61 FR 1322, 01/19/ 1996); Whereas, the City of Phoenix has advised that zone procedures are no longer...., Phoenix, AZ Pursuant to its authority under the Foreign-Trade Zones Act of June 18, 1934, as amended (19 U... issued a grant of authority to the City of Phoenix (grantee of FTZ 75) authorizing the establishment...

  5. Temporal and spatial patterns in tumour prevalence in brown bullhead Ameiurus nebulosus (Lesueur) in the tidal Potomac River watershed (USA).

    PubMed

    Pinkney, A E; Harshbarger, J C; Rutter, M A

    2014-10-01

    For two decades, fish tumour surveys have been used to monitor habitat quality in the Chesapeake Bay (USA) watershed. Tributaries with sediments contaminated with polynuclear aromatic hydrocarbons (PAHs), known to cause liver neoplasia, were frequently targeted. Here, we compare surveys in brown bullhead Ameiurus nebulosus conducted in 2009-2011 in the tidal Potomac River watershed (including the Anacostia River) with previous surveys. Using logistic regression, we identified length and sex as covariates for liver and skin tumours. We reported a statistically significant decrease in liver tumour probabilities for standardized 280mm Anacostia bullheads between the 1996 and 2001 samplings (merged collections: female-77.5%, male-43.0%) and 2009-2011 (female-42.2%, male-13.6%). However, liver tumour prevalence in bullheads from the Anacostia, Potomac River (Washington, DC) and Piscataway Creek (17km downriver) was significantly higher than that for Chesapeake Bay watershed reference locations. The causes of skin tumours in bullheads are uncertain, requiring further research. The similar liver tumour prevalence in these three locations suggests that the problem is regional rather than restricted to the Anacostia. To monitor habitat quality and the success of pollution control actions, we recommend conducting tumour surveys on a 5-year cycle coordinated with sediment chemistry analyses. PMID:24974857

  6. Aroclor 1248 exposure leads to immunomodulation, decreased disease resistance and endocrine disruption in the brown bullhead, Ameiurus nebulosus

    USGS Publications Warehouse

    Iwanowicz, L.R.; Blazer, V.S.; McCormick, S.D.; Van Veld, P.A.; Ottinger, C.A.

    2009-01-01

    The brown bullhead Ameiurus nebulosus is a species of the family Ictaluridae commonly used as a sentinel of environmental contamination. While these fish have been utilized for this purpose in areas contaminated with polychlorinated biphenyls (PCBs), few controlled, laboratory-based studies have been designed to document the effects of PCB mixtures in this species. Here, brown bullhead were exposed to the PCB mixture, Aroclor 1248, via intraperitoneal injection and the effects on immune function, plasma hormones and disease resistance were evaluated. Exposure to this mixture led to a decrease in bactericidal activity and circulating antibodies to Edwardsiella ictaluri present from a previous exposure to this pathogen. A subsequent E. ictaluri disease challenge led to significantly higher mortality in A1248 treated fish compared to vehicle-control fish. The mitogenic response to the T-cell mitogen, phytohemaglutinin-P, was increased compared to vehicle-control fish. The steroid hormone, cortisol, and the thyroid hormone, T3, were also significantly lower in A1248 exposed fish. In summary, we have validated a number of functional immune assays for application in brown bullhead immunotoxicity studies. Additionally, we have demonstrated that the PCB mixture (A1248) modulates both immune function and endocrine physiology in brown bullhead. Such data may compliment the interpretation of data yielded from applied field studies conducted in PCB contaminated aquatic ecosystems.

  7. HISTORICAL MONITORING OF BIOMARKERS OF PAH EXPOSURE OF BROWN BULLHEAD IN THE REMEDIATED BLACK RIVER AND THE CUYAHOGA RIVER, OHIO

    EPA Science Inventory

    Biomarkers of exposure to chemical contamination were measured in brown bullhead from a heavily PAH contaminated section of the Black River, Ohio, during and immediately after remedial sediment dredging in 1990-1991, and in follow-up visits in 1993 and 1998. Biomarker levels of ...

  8. Az-Tech Medicine.

    ERIC Educational Resources Information Center

    Nicholson, Rob

    2000-01-01

    Created in 1552 as a gift for Spain's king, the Badianus Manuscript is a repository of Aztec traditional medicinal knowledge and contains the earliest surviving illustrations of New World plants. At the College of Santa Cruz (Mexico City) for Aztec nobility, an Aztec healer who became the college physician compiled plant descriptions and medicinal

  9. Dna damage and external lesions in brown bullheads (Ameiurus Nebulosus) from contaminated habitats.

    PubMed

    Yang, Xuan; Meier, John; Chang, Lina; Rowan, Michael; Baumann, Paul C

    2006-11-01

    The Comet assay was used to compare levels of DNA damage in brown bullheads (Ameiurus nebulosus) collected from three known contaminated locations, the Cuyahoga River (OH, U.S.A.), Ashtabula River (OH, U.S.A.; both tributaries to Lake Erie, USA), and Ashumet Pond (Cape Cod, MA, U.S.A.), with brown bullheads collected from three paired reference sites, Old Woman Creek (OH, U.S.A.), Conneaut River (OH, U.S.A.; both tributaries to Lake Erie), and Great Herring Pond (mainland MA, U.S.A.), respectively. Blood was sampled from each fish, and the Comet assay was conducted on erythrocytes. The assay results demonstrate that fish from the three contaminated sites each suffered higher DNA damage compared with fish from their respective reference sites. The results also show that the genetic damage was associated with the occurrence of external lesions and deformities in fish. The Comet assay is sufficiently sensitive to detect exposure of natural fish populations to environmental levels of genotoxic contaminants. PMID:17089728

  10. Mitochondrial DNA diversity of brown bullhead from contaminated and relatively pristine sites in the Great Lakes

    SciTech Connect

    Murdoch, M.H.; Hebert, P.D.N. . Dept. of Zoology)

    1994-08-01

    Brown bullhead were sampled from contaminated and relatively pristine sites to determine whether there was any association between genetic diversity and site contamination. Nine sites were sampled in the lower Great Lakes: five from Areas of Concern (identified by the International Joint Commission as having significant environmental degradation) and four from relatively clean areas of similar habitat type. Genetic variation was surveyed in the mitochondrial genome using restriction fragment length polymorphisms. Sixteen restriction enzymes were used to identify 42 distinct mitochondrial DNA haplotypes among 163 fish. Eight pairwise comparisons of populations at contaminated vs. clean sites showed that genetic diversity estimates were always lower in populations from contaminated sites. The most parsimonious explanation is that reduced diversity is a result of stochastic reductions in population size that have culled much of the genetic diversity from populations. Although contaminated sites support large populations of brown bullhead, historical environmental degradation at these sites may have reduced population size in the past, resulting in reduced present-day genetic diversity.

  11. Chlordane, DDT, PCB's, and other selected organic compounds in Asiatic clams and yellow bullhead in the Potomac River Basin, 1992

    USGS Publications Warehouse

    Zappia, Humbert

    1996-01-01

    Chlordane, DDT (dichlor-diphenyl-trichloroethane), and PCB's (polychlorinated biphenyls) were the most widespread organic contaminants detected during a 1992 survey of aquatic biological tissues in the Potomac River Basin. On the basis of existing U.S. Food and Drug Administration criteria, no new threats to human health were discovered, although chlordane concentrations may pose a threat to fish-eating wildlife. Chlordane exceeded the National Academy of Science and National Academy of Engineering recommended maximum concentration for the protection of fish-eating wildlife at two sites. The survey, conducted by the U.S. Geological Survey's National Water-Quality Assessment Program, sampled Asiatic clams (Corbicula fluminea) and yellow bullhead (Ameiurus natalis) at 16 sites to determine the occurrence and distribution of 29 hydrophobic organic compounds. Thirteen of these organic compounds were detected in the survey. Sites with the greatest number of compounds detected include the Potomac River near Alexandria, Va., with 6 compounds detected in Asiatic clam tissue, and Accotink Creek near Annandale, Va., with 11 compounds in yellow bullhead tissue. Chlordane was detected at six sites, with maximum concentrations of 31.1 ?g/kg (micrograms per kilograms) in Asiatic clam tissue and 127 ?g/kg in yellow bullhead whole-fish tissue. DDT was detected at five sites, with maximum concentrations of 12.9 ?g/kg in Asiatic clam tissue and 7.6 ?g/kg in yellow bullhead whole-fish tissue. PCB's were detected at nine sites, with maximum concentrations of 162 ?g/kg in Asiatic clam tissue and 146 mg/ kg in yellow bullhead whole-fish tissue.

  12. Synchronous fluorometric measurement of metabolites of polycyclic aromatic hydrocarbons in the bile of brown bullhead

    SciTech Connect

    Lin, E.L.C.; Cormier, S.M. . Environmental Monitoring Systems Lab.); Racine, R.N.

    1994-05-01

    A synchronous fluorescent spectroscopy (SFS) method was developed to measure pyrene-type metabolites in the bile of brown bullhead (Ameiurus nebulosus) and to estimate the exposure of fish to PAHs in four Lake Erie tributaries collected in the spring and fall of 1990 and 1991. For comparison, fish biliary benzo[a]pyrene (B[a]P) metabolites were also measured by HPLC/fluorescent detection (HPLC/F). Both methods showed that concentrations of biliary PAH metabolites of fish collected in polluted rivers were significantly higher than those collected from reference rivers. Concentrations biliary metabolites of fish caught in the Black River were five to 20 times greater than those collected in Old Woman Creek by SFS and three to five times greater by HPLC/F. Fish from the Cuyahoga River had four to 24 times more biliary PAH metabolites than fish from Old Woman Creek, measured by SFS, and five to 10 times more, measured by HPLC/F. Brown bullhead from the Toussaint River had fewer PAH metabolites than fish from Old Woman Creek. Correlation analyses of the two sets of data obtained by SFS and HPLC/F showed significance by both Pearson's sample correlation and Spearman's rank correlation. This study indicates that pyrene-type metabolites determined by SFS can be used to estimate B[a]P-type metabolites in fish bile. SFS appears to be a highly sensitive method for detecting PAH metabolites and, because of its simplicity, a cost-efficient method for screening large numbers of samples for exposure to PAHs in fish.

  13. Decline in liver neoplasms in wild brown bullhead catfish after coking plant closes and environmental PAHs plummet

    SciTech Connect

    Baumann, P.C.; Harshbarger, J.C.

    1995-02-01

    Polycyclic aromatic hydrocarbons (PAHs) in both sediment and brown bullhead catfish tissues from the Black River in Lorain County, Ohio, declined by 65% and 93%, respectively, between 1980 and 1982. Sediment PAHs declined an additional 99% by 1987, coincident with the closure of a coking facility in 1983. Contemporaneously, liver cancer in 3- to 4-year-old brown bullheads declined to about one-quarter the 1982 frequency (10% versus 39%) by 1987, while the percentage of livers without any proliferative lesions doubled (42% versus 20%). These changes were significant within age group. Our data affirm a cause-and-effect relationship between PAH exposure and liver cancer in wild fish. The data also support the efficacy of natural, unassisted remediation once the source of the pollution is eliminated. 21 refs., 4 tabs.

  14. Tumor prevalence and biomarkers of exposure in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River, USA, watershed

    USGS Publications Warehouse

    Pinkney, A.E.; Harshbarger, J.C.; May, E.B.; Melancon, M.J.

    2001-01-01

    Associations between contaminant exposure and liver and skin tumor prevalence were evaluated in brown bullheads (Ameiurus nebulosus) from the tidal Potomac River, USA, watershed. Thirty bullheads (>age 3) were collected from Quantico embayment near a Superfund site that released organochlorine contaminants; Neabsco Creek, a tributary with petroleum inputs from runoff and marinas; and Anacostia River (spring and fall), an urban tributary designated as a Chesapeake Bay region of concern, that was contaminated with polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides. Fish were collected from the Tuckahoe River, as a reference. Cytochrome P450 activity, bile PAH metabolites, and muscle organochlorine pesticide and PCB concentrations were measured in randomly selected individuals and sediment contaminants were analyzed. We found statistically significant differences in liver tumor prevalences: Anacostia (spring), 50%, Anacostia (fall), 60%, Neabsco, 17%, Quantico, 7%, and Tuckahoe, 10%. Skin tumor prevalences were significantly different: Anacostia (spring), 37%, Anacostia (fall), 10%, Neabsco, 3%, Quantico, 3%, and Tuckahoe, 0%. Tumor prevalences in Anacostia bullheads warrants concern and was similar to those as highly contaminated sites in the Great Lakes. Evidence was found of higher PAH exposure in Anacostia fish but a cause-effect linkage could not be established. Fish tumor surveys, with histopathologic examination of internal and external organs are recommended for monitoring the status of regions of concern.

  15. 75 FR 10552 - Noise Exposure Map Notice for Chandler Municipal Airport, Chandler, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-08

    ... Federal Aviation Administration Noise Exposure Map Notice for Chandler Municipal Airport, Chandler, AZ... Administration (FAA) announces its determination that the noise exposure maps submitted by City of Chandler, for Chandler Municipal Airport under the provisions of 49 U.S.C. 47501 et seq. (Aviation Safety and...

  16. 75 FR 20920 - Safety Zone; Lake Havasu Grand Prix, Lake Havasu, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-22

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Havasu Grand Prix, Lake Havasu, AZ... temporary safety zone upon the navigable waters of Lake Havasu on the Colorado River in Lake Havasu City, Arizona for the Lake Havasu Grand Prix. This temporary safety zone is necessary to provide for the...

  17. The AzTEC Mathematics Project (AMP).

    ERIC Educational Resources Information Center

    Johnson, Gae R.

    The AzTEC Mathematics Project (AMP) is a statewide partnership among Arizona's Regents universities and state community colleges, partner school districts, and economic communities. AzTec is committed to preparing highly qualified K-12 mathematics and science teachers. AMP targeted Native American teachers and teachers of Native American students

  18. Susceptibility of black bullhead Ameiurus melas to a panel of ranavirus isolates.

    PubMed

    Gobbo, F; Cappellozza, E; Pastore, M R; Bovo, G

    2010-07-01

    Ranaviruses are considered a serious threat to lower vertebrates, including fish, amphibians and reptiles. However, epidemiological data on these agents are lacking, and further investigations are needed to understand the role of carriers and to update the list of susceptible hosts. We carried out various experimental infections under controlled conditions to contribute to the current knowledge on the susceptibility of black bullhead Ameiurus melas to European catfish virus (ECV) and other ranaviruses. A panel of 7 ranavirus isolates was used to challenge duplicate groups of A. melas juveniles maintained in aquaria supplied with running dechlorinated tap water. The experiments were performed at 15 and 25 degrees C. The results confirmed the high susceptibility of A. melas to ECV infection. Furthermore, a significant mortality associated with the typical signs of systemic viral infections was observed in groups challenged with Epizootic haematopoietic necrosis virus (EHNV) at 25 degrees C, and to a lesser extent, at 15 degrees C. No significant mortality was recorded in fish challenged with European sheatfish virus (ESV), Frog virus 3 (FV3), Rana esculenta virus-like (REV-like), Bohle iridovirus (BIV) or short-finned eel virus (SERV). PMID:20815324

  19. Estimates of population genetic diversity in brown bullhead catfish by DNA fingerprinting

    SciTech Connect

    Roth, A.C.; Wessendarp, T.K.; Gordon, D.A.; Smith, M.K.; Lattier, D.L.; Hertzberg, V.; Leonard, A.

    1994-12-31

    Estimates of population genetic diversity may be a sensitive indicator of environmental impact, since limiting the effective breeding population by any means will result in loss of some variant genotypes, as has been demonstrated by allozyme analysis. DNA fingerprinting techniques are also coming into use for population analyses, and the authors chose to apply fingerprinting analysis three populations of brown bullhead catfish collected in Northern Ohio. DNA was isolated from the red blood cells of individual fish. Purified DNAs were digested with EcoR1 restriction enzyme; the digests were then sized on a 1% agarose gel, transferred to nylon membranes and probed with a radiolabeled M13 probe using the Westneat hybridization protocol (Southern blotting). This method effects fragments containing VNTR (variable number of tandem repeat) sequences complementary to the M13, which are highly variable among individual catfish. Hybridized bands were visualized by a Molecular Dynamics phosphorimager and recorded and analyzed with its proprietary Imagequant image analysis program, Excel and SAS. A total of 10 variable bands were identified and their presence or absence scored in each individual. These data were analyzed to determine between and within-population similarity indices as well as population heterozygosity and genetic diversity measures.

  20. Flow cytometric leukocyte population patterns in brown bullhead from three Ohio rivers

    SciTech Connect

    Torsella, T.A.; Neiheisel, T.; Cormier, S.M.; Bercz, P.

    1994-12-31

    Brown bullhead (A. nebulosus) were collected from three Ohio rivers: Old Woman Creek (OWC), classified as clean, Cuyahoga (CR) and Black Rivers (BR), documented as polluted. Each river was sampled in April and September 1993. Patterns of leukocyte distribution (prepared via density gradient) by GSH content and oxidative burst capacity, using fluorescent probes were determined by flow cytometry. Sample processing was in blind coded batches. Three principal classes of leukocytes were identified. Type A; large, very granular with high GSH reserves and marked capacity for oxidative burst. Type B were smaller, less granular, contained low GSH and negligible oxidative burst capacity. Type C were small, less granular, possessing intermediate GSH and peroxidative activity. ANOVA of the subset distributions and mean fluorescent intensities by sex, site and season, disclosed: Type C were significantly (p < 0.001) elevated in the spring OWC males, whereas type A dominated in the spring CR and spring BR males. No differences in Type A/Type C patterns were seen in the spring females. In the fall sampling, significant dominance (p < 0.001) of Type A was seen in both sexes of the OWC fish, the CR and BR fish showed a predominance of Type C. These may be explained by chemical stressors, affecting immune competence. Sex differences in the spring were attributed to hormonal (spawning) influences.

  1. Bioaccumulation of cesium-137 in yellow bullhead catfish (Ameiurus natalis) inhabiting an abandoned nuclear reactor reservoir

    SciTech Connect

    McCreedy, C.D.; Glickman, L.T.; Jagoe, C.H.; Brisbin, I.L. Jr.

    1997-02-01

    Bioaccumulation of {sup 137}Cs was investigated in yellow bullhead catfish (Ameiurus natalis) inhabiting an abandoned reactor reservoir, Pond B, Savannah River Site, Barnwell Co., South Carolina. The authors collected fish by trap-netting, and determined ages from pectoral spines. Muscle and other tissues were assayed for {sup 137}Cs by NaI-scintillation. Music {sup 137}Cs was unrelated to sex or mass of fish, but was related to age. Examination of least-squares means suggested that {sup 137}Cs in muscle increased up to about age 3, but did not increase with greater age. A modified Richards model showed equilibrium {sup 137}Cs concentration in muscle was acquired in approximately 2.4 years. Growth differed between sexes and the time to asymptotic body mass was longer than the time to attain equilibrium {sup 137}Cs concentration. Males attained an asymptotic mass of 577 g in approximately 6.3 years; females attained an asymptotic mass of 438 g in approximately 5.9 years. The cumulative {sup 137}Cs burden of the population was 4.9 {times} 10{sup 6} Bq, representing <0.001% of the {sup 137}Cs inventory of the reservoir. Concentration of {sup 137}Cs varied among tissues with gill and muscle the lowest and highest. Concentration of {sup 137}Cs in ovaries declined with increasing ovary mass. Until equilibrium is attained in these fish, {sup 137}Cs concentration is directly related to increasing age rather than size.

  2. Antibodies against enteric bacteria in brown bullhead catfish (Ictalurus nebulosus, LeSueur) inhabiting contaminated waters.

    PubMed

    Troast, J L

    1975-08-01

    Brown bullhead catfish were collected from sewage- and acid mine waste-polluted waters in an attempt to detect antibodies against human enteric bacteria in their sera and to investigate the association of antibody response with environmental conditions. Agglutination antigens prepared from isolates obtained from water collected at the same locations as the fish habitats were used to demonstrate such antibodies. The results showed large percentages of reactive sera for common isolates such as Escherichia coli and Enterobacter cloacae as well as lesser incidences of antibodies to other, less common isolates. In general, fish with the highest titres were collected from habitats with higher coliform counts. Acid mine drainage reduced the total coliform counts, but did not appear to affect the titers of sera from fish collected from water so affected. It was concluded that the bottom-feeding catfish might be a better subject for the study of fish as an ecological indicator of fecal pollution in acid-polluted waters. PMID:1099987

  3. Biliary PAH metabolites and the hepatosomatic index of brown bullheads from Lake Erie tributaries

    USGS Publications Warehouse

    Yang, X.; Baumann, P.C.

    2006-01-01

    In studies designed to investigate the environmental exposure of fish in Lake Erie tributaries, a benthic fish, the brown bullhead (Ameiurus nebulosus), was collected from the industrially contaminated Detroit River, Ottawa River, Black River, Cuyahoga River-harbor and -upstream, Ashtabula River, Buffalo River, and Niagara River, and the non-industrialized Old Woman Creek during 1997-2000. Biliary benzo[a]pyrene (B[a]P)- and naphthalene (NAPH)-type metabolites and the hepatosomatic index (HSI) were measured in fish and compared between different sites. Fish from all of the contaminated sites except Niagara River had significantly higher concentrations of both types of polycyclic aromatic hydrocarbon (PAH) metabolites than fish from the Old Woman Creek. Concentrations of PAH metabolites in bile of fish were positively associated with concentrations of PAHs in sediments, supporting the use of bile metabolites as a measure of PAH exposure. Relatively low concentrations of PAHs detected in fish bile and sediments of the Niagara River, which had undergone extensive remediation, suggested a lowered PAH exposure for fish at this site. No apparent trend was observed in HSI between the industrialized and non-industrialized sites. This study demonstrates that biliary PAH metabolites are an effective indicator of exposure of fish to PAHs. However, because factors other than contamination could also affect the liver size of wild fish, HSI alone may be not a reliable biomarker for assessing contaminant stress. ?? 2005 Elsevier Ltd. All rights reserved.

  4. Assessment of the fish tumor beneficial use impairment in brown bullhead (Ameiurus nebulosus) at selected Great Lakes Areas of Concern

    USGS Publications Warehouse

    Blazer, Vicki; Mazik, Patricia M.; Iwanowicz, Luke R.; Braham, Ryan P.; Hahn, Cassidy M.; Walsh, Heather L.; Sperry, Adam J.

    2014-01-01

    A total of 878 adult Brown Bullhead were collected at 11 sites within the Lake Erie and Lake Ontario drainages from 2011 to 2013. The sites included seven Areas of Concern (AOC; 670 individuals), one delisted AOC (50 individuals) and three non-AOC sites (158 individuals) used as reference sites. These fish were used to assess the fish tumor or other deformities beneficial use impairment. Fish were anesthetized, weighed, measured and any external abnormalities documented and removed. Abnormal orocutaneous and barbel tissue, as well as five to eight pieces of liver, were preserved for histopathological analyses. Otoliths were removed and used for age analyses. Visible external abnormalities included reddened (raised or eroded), melanistic areas and raised growths on lips, body surface, fins and barbels. Microscopically, these raised growths included papilloma, squamous cell carcinoma, osteoma and osteosarcoma. Proliferative lesions of the liver included bile duct hyperplasia, foci of cellular alteration, bile duct (cholangioma, cholangiocarcinoma) and hepatocellular (adenoma, hepatic cell carcinoma) neoplasia. The two reference sites (Long Point Inner Bay, Conneaut Creek), at which 30 or more bullhead were collected had a skin tumor prevalence of 10% or less and liver tumor prevalence of 4% or less. Presque Isle Bay, recently delisted, had a similar liver tumor prevalence (4%) and slightly higher prevalence (12%) of skin tumors. The prevalence of skin neoplasms was 15% or less at sites in the Black River, Cuyahoga River and Maumee AOCs, while more than 20% of the bullheads from the Rochester Embayment, Niagara River, Detroit River and Ashtabula River AOCs had skin tumors. The prevalence of liver tumors was greater than 4% at all AOC sites except the Old Channel site at the Cuyahoga River AOC, Wolf Creek within the Maumee AOC and the upper and lower sites within the Niagara River AOC.

  5. Fluorescent aromatic hydrocarbons in bile as a biomarker of exposure of brown bullheads (Ameiurus nebulosus) to contaminated sediments

    SciTech Connect

    Leadly, T.A.; Haffner, G.D.; Arcand-Hoy, L.D.; Metcalfe, C.D.

    1999-04-01

    Analysis of fluorescent aromatic compounds (FACs) in the bile of fish has been widely used as a biomarker of exposure to polynuclear aromatic hydrocarbon (PAH) contamination. However, bile FAC data for feral fish populations are typically highly variable, and in a few cases, elevation of FACs has not been observed in fish from contaminated areas. In this study, the bile FACs and hepatic ethoxyresorufin-O-deethylase activity in brown bullheads (Ameiurus nebulosus) exposed in the laboratory to contaminated sediments from Hamilton Harbour, Ontario, Canada, increased by 173-fold within 72 h of initial exposure and rapidly declined thereafter. In bullheads caged in the contaminated Trenton Channel area of the Detroit River, bile FACs also increased rapidly within 4 d of initial exposure to mean levels >3,000 ng of benzo[a]pyrene equivalents per milliliter of bile. Surprisingly, there was no difference in the mean-levels of bile FACs in fish caged above the sediment versus fish caged in direct contact with the sediment, indicating that water may be the major vector for uptake of PAHs. The lower bile FACs in bullheads caged in other regions of the Detroit River were consistent with the lower concentrations of PAHs in the sediments from these areas. These data indicate that bile FAC levels are a biomarker of recent exposure to aromatic hydrocarbons in sediments. However, FAC data were highly variable even in these studies, in which fish were relatively homogenous in size, feeding status, and exposure history. Therefore, Even higher variability in bile FAC data are expected in biomarker studies as a result of differences in reproductive status, size, diet, and mobility of the fish.

  6. 20. Streetscape, South Coronado Boulevard, looking southwest Righttoleft, AZ198(Margaret B. ...

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

    20. Streetscape, South Coronado Boulevard, looking southwest Right-to-left, AZ-198(Margaret B. Hill House), AZ-199 (Henry H. Hill House), AZ-200 (Henry H. Hill Rental House), AZ-201 (Otto Rosenthal House), AZ-202 (J. M. Stevens House), AZ-203 (L J. Dunagan House), AZ204 (C. W. Beck House), and AZ-205 (F. D. Connor House) face the street - Clifton Townsite, Confluence of Chase Creek & San Francisco River, Clifton, Greenlee County, AZ

  7. Pigmented macrophage aggregates as a biomarker of oxidative damage in yellow bullhead catfish, Ameiurus natalis

    SciTech Connect

    McCreedy, C.D.; HoganEsch, H.; Turek, J.; Jagoe, C.H.

    1995-12-31

    Pigmented macrophage aggregates (PMs) occur when peroxidized lipids resulting from oxidative damage in tissues are scavenged by macrophages. Ionizing radiation causes oxidative damage, so the authors evaluated PMs as a biomarker in the pronephros of yellow bullheads (Ameiurus natalis) inhabiting Pond B, Savannah River Site, SC, a reservoir contaminated with low levels of {sup 137}Cs. ANOVA, ANCOVA, and stepwise regression were used to relate the mean number of PMs, per 0.15 mm{sup 2} of tissue section, to fish sex (females: N = 61; males: N = 84), age (1--6 yrs), body-condition, and muscle {sup 137}Cs concentration. Mean pronephric PMs differed by six and with fish muscle {sup 137}Cs concentration. Among males, PMs were positively correlated with fish age and {sup 137}Cs. In females, PMs were also correlated with fish age and {sup 137}Cs. ANCOVA, with age as covariate, affirmed that sex and muscle {sup 137}Cs were significantly associated with the mean number of pronephric PMs. Using stepwise regression, the interaction of age and {sup 137}Cs concentration was most strongly associated with pronephric PMs in males. Among females, the product of age, body-condition, and {sup 137}Cs concentration was most strongly associated with pronephric PMs. The positive relationships between the number of pronephric PMs and {sup 137}Cs concentration suggest that oxidative damage related to long-term exposure to low-level radiation is detectable in these fish. Secondarily, these results demonstrate the importance of considering covariates such as age and sex when evaluating effects of environmental contaminants.

  8. Sediment PAHs and tumors in brown bullhead (Ameiurus nebulosus) at Featherstone National Wildlife Refuge, Virginia

    SciTech Connect

    Pinkney, A.E.; Sutherland, D.W.; Foley, R.E.; Harshbarger, J.C.

    1995-12-31

    Featherstone National Wildlife Refuge is located in Virginia along the Potomac River, about 35.4 kilometers southwest of Washington, DC. The study objective was to verify past observations of gross lesions in several fish species, previously collected from Potomac River tributaries for contaminant analysis. Thirty brown bullhead (Ameiurus nebulosus) were collected from Neabsco Creek, which borders the refuge, 29 were collected from Farm Creek, which bisects the refuge, and 30 were collected from Marumsco Creek, 1.75 km upstream. Sediment concentrations of polynuclear aromatic hydrocarbons (PAHS) were measured because elevated levels have been associated with skin and liver tumors in this species. The average concentration of total carcinogenic PAHs in sediments was: Farm Creek (0.34 ppm) < Marumsco Creek (0.63 ppm) < Neabsco Creek (1.37 ppm). The prevalence of skin neoplasms (squamous carcinomas and papillomas) was 3.4% in Farm Creek, 16.6% in Marumsco Creek, and 33.3% in Neabsco Creek. This ranking and the rankings of the total number of fish with tumors, invasive tumors, or non-parasitic lesions all followed the trend in sediment carcinogenic PAHs (p < 0.003; Jongheere-Terpstra test). The prevalence of liver carcinomas (O% at Farm Creek, 3.3% at Marumsco Creek, and 10% at Neabsco Creek) was of borderline significance (p = 0.06). The highest sediment concentrations of total (25.5 ppm) and carcinogenic (2.70 ppm) PAHs were found in Neabsco Creek near a complex of three marinas. Further sampling should be conducted in Neabsco Creek to determine the sources and extent of PAH contamination. Laboratory exposures are recommended for establishing a cause-effect linkage between sediment and tumor incidence. Additional sediment chemistry is needed to determine if other carcinogens are present.

  9. PCB accumulation in Hudson River pumpkinseed sunfish and bullhead: Influences of invertebrate prey

    SciTech Connect

    Feldman, R.S.

    1992-01-01

    Hudson River sediments are contaminated with PCBs, and these toxic compounds are also in the water and have accumulated in food chains. The relative importance of exposure by fish to contaminated water vs. contaminated prey was unknown. further, is was not known if difference in diet could influence fish PCB levels. Invertebrates and fish were sampled in different habitats to address these issues. Invertebrate communities differed in several ecological measures between two different plant beds, and among experimentally manipulated habitats in one plant bed. Communities often differed significantly in parameters such as total invertebrate density, densities of individual taxa, taxonomic richness and similarity, and size distributions; some taxa were also absent from one habitat but present in another. Total PCBs differed significantly for invertebrate communities between the two plant beds (9.4 vs. 31.4 [mu]g/g), and between some of the communities in the manipulated habitats (1.8 vs 5.3 [mu]g/g). These differences did not translate into difference in PCBs among fish that fed in the different habitats. However, bullhead had significantly higher levels than pumpkinseed (15.4 vs. 6.9 [mu]g/g). Yearling pumpkinseed that fed on Hudson River invertebrates had 5x the PCB levels of pumpkinseed exposed for the same period to the water but not to the prey, and 18x as much PCBs as fish unexposed to either Hudson River water or prey. Further, fish that fed on local prey had a higher proportion of high-Cl isomers than those exposed only to the contaminated water. Fish that fed in different habitats did not have different PCB levels. Thus, the role of diet needs further experimentation, but it is clear that local prey are the major route for PCB accumulation in yearling pumpkinseed.

  10. Precipitation Simulation of AZ91 Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Cao, W.; Chen, S.-L.; Zhu, J.; Zhang, F.; Luo, A. A.; Schmid-Fetzer, R.

    2014-03-01

    Precipitation simulation of AZ91 (Mg-9Al-1Zn; all compositions are in wt.% unless otherwise stated.) magnesium alloy is carried out in this work using the PanPrecipitation module of Pandat software. In addition to the software, the thermodynamic database, mobility database, and precipitation database for AZ91 were developed to perform the simulation. The simulated results, such as the number density and particle size of the ?-Mg17Al12 precipitate, showed good agreement with the experimental data. Moreover, the simulated results were then used as input for the prediction of yield strength and micro-hardness of AZ91 aged at different temperatures, which also agreed well with experimental results. To demonstrate the applicability of the databases developed for AZ91, simulations were also carried out for two compositions with lower and higher Zn content. The simulated hardness showed reasonable agreement with the published experimental data.

  11. Spectroscopic Classification of ASASSN-16az

    NASA Astrophysics Data System (ADS)

    Prieto, J. L.; Rich, J.; Shappee, B. J.

    2016-02-01

    We obtained an optical spectrum (range 360-920 nm) of ASASSN-16az (ATel #8614) on UT 2016 Feb 2.4 with WFCCD mounted on the du Pont 2.5m telescope at Las Campanas Observatory. Cross-correlation with a library of SN spectra using SNID (Blondin & Tonry 2007, ApJ, 666, 1024) shows that ASASSN-16az is a normal Type Ia at +10 days.

  12. Perfil de Franklin Chang- Díaz de Franklin Chang-Díaz - Duration: 117 seconds.

    NASA Video Gallery

    Franklin Chang-Díaz, el primer astronauta hispano de la NASA, habla sobre qué lo inspiró a trabajar con cohetes y convertirse en astronauta. Chang-Díaz alienta a los jóvenes para que sigan sus sueños.

  13. Assessing the ecosystem service potential of Tucson AZ's urban forest

    NASA Astrophysics Data System (ADS)

    Pavao-Zuckerman, M.

    2011-12-01

    Urbanization is arguably one of the most dramatic forms of landscape change, and an important anthropogenic influence on the structure and function of ecosystems. Cities have obvious impacts on local ecologies and environments, such as shifts in species diversity and alteration of local microclimates. While scientists are now familiar with many of these localized impacts of urbanization, cities and suburban areas contribute to 10-15 % of surface land cover in the conterminous U.S., pointing to the potential, yet poorly understood, contribution of cities to regional, national, and global carbon (C) and energy budgets. As cities continue to expand urban ecologists place more emphasis on understanding the functions of urban ecosystems and the ecosystem services (e.g. habitat, air, and water quality) that cities provide. While studies demonstrate that the urban environment alters the structure and function of remnant patches of native ecosystems relative to their non-urban counterparts, the ability of restoration, planning, and design to improve the provision of ecosystem services is a new approach within ecology. One strategy involves green urban design, or using ecological principles for planning or reinvigorating certain ecological processes, in cities. Increasing the amount of vegetative cover can reduce this effect by reinforcing ecosystem services in cities, including shading of surfaces, promotion of cooling through evapotranspiration, and the sequestration of atmospheric CO2 in plant tissues and soils. However, the on-the-ground reality of such strategies is relatively unknown. A pilot study is being conducted in Tucson, AZ to investigate the impact of increasing the cover of trees in the urban landscape on local microclimates and the urban heat island. Trees (Velvet Mesquite, Chilean Mesquite, and Desert Willow) were planted in two neighborhoods in Tucson in 1990. We are collecting data during the summer 2011 monsoon (DBH, crown volume, and hemispherical canopy photos) to asses growth of the trees in the urban environment. These growth rates, and associated ecosystem services (C-sequestration, energy savings, pollution mitigation, etc.) are evaluated using US Forest Service models (Tree Carbon Calculator and i-tree software) to determine how the performance of trees in the Tucson urban environment perform vs. model predictions. We hypothesize that the models overestimate tree performance as Tucson differs in water availability relative to the cities the model was parameterized in (e.g. Glendale), both in terms of soil water holding capacities and also city "water culture." This preliminary study will provide a data collection framework for a citizen science urban forestry project which will provide data to improve environmental decision making related to the interaction of plants, water, and energy balance in this arid city.

  14. Characterization of the histone H2A.Z-1 and H2A.Z-2 isoforms in vertebrates

    PubMed Central

    2009-01-01

    Background Within chromatin, the histone variant H2A.Z plays a role in many diverse nuclear processes including transcription, preventing the spread of heterochromatin and epigenetic transcriptional memory. The molecular mechanisms of how H2A.Z mediates its effects are not entirely understood. However, it is now known that H2A.Z has two protein isoforms in vertebrates, H2A.Z-1 and H2A.Z-2, which are encoded by separate genes and differ by 3 amino acid residues. Results We report that H2A.Z-1 and H2A.Z-2 are expressed across a wide range of human tissues, they are both acetylated at lysine residues within the N-terminal region and they exhibit similar, but nonidentical, distributions within chromatin. Our results suggest that H2A.Z-2 preferentially associates with H3 trimethylated at lysine 4 compared to H2A.Z-1. The phylogenetic analysis of the promoter regions of H2A.Z-1 and H2A.Z-2 indicate that they have evolved separately during vertebrate evolution. Conclusions Our biochemical, gene expression, and phylogenetic data suggest that the H2A.Z-1 and H2A.Z-2 variants function similarly yet they may have acquired a degree of functional independence. PMID:20003410

  15. Recommendations to design environmental monitoring in the European bullhead, Cottus sp., based on reproductive cycle and immunomarker measurement.

    PubMed

    Bado-Nilles, Anne; Villeret, Mlanie; Geffard, Alain; Palluel, Olivier; Blanchard, Christophe; Le Rohic, Cindy; Besson, Sylvain; Porcher, Jean-Marc; Minier, Christophe; Sanchez, Wilfried

    2015-06-30

    European bullhead is a relevant fish species to assess adverse effects of environmental stress on wild fish. Nevertheless, their complex reproductive cycle is very different between sites and could interfere with many physiological processes. Thus, prior to use biomarker to statute on environmental quality of rivers, we wanted to characterize reproductive profile (spawn number, GSI, gonad development). The major results demonstrated that the two types of reproductive cycle shown were strongly correlated to water temperature variation. In a second time, even if innate immunomarkers are highly relevant on biomonitoring program, hormonal variation seems to impact severely their responses. Thus, the link between reproductive status and immune activity (leucocyte distribution, cellular mortality, respiratory burst, phagocytosis activity) must also be study. Nonetheless, in the present work, immune capacities seems to be more correlated with season and environmental factors than reproduction. PMID:25599631

  16. 33 CFR 100.1102 - Annual marine events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... application each year as required by 33 CFR part 100, subpart A, to the cognizant Coast Guard Sector Commander... to La Paz County Park. 4. Desert Storm Sponsor Lake Racer LLC. Event Description Boat Poker Run...

  17. 33 CFR 100.1102 - Marine Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., Nevada, from the Pioneer Hotel to the Edgewater Hotel. Laughlin Aquamoto Sports Challenge and Expo.... PDT. Where: That portion of the Colorado River near Laughlin, Nevada, from Davis Dam to Harrah's...

  18. 33 CFR 100.1102 - Marine Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., Nevada, from the Pioneer Hotel to the Edgewater Hotel. Laughlin Aquamoto Sports Challenge and Expo.... PDT. Where: That portion of the Colorado River near Laughlin, Nevada, from Davis Dam to Harrah's...

  19. 33 CFR 100.1102 - Annual Marine Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Colorado River on the California side at Havasu Landing Resort and Casino. 3. Parker International Water...? N, 11418?52? W. 6. BlueWater Resort and Casino Spring Classic Sponsor Southern California Speedboat... application each year in accordance with 33 CFR 100.15 to the cognizant Coast Guard Sector Commander no...

  20. 33 CFR 100.1102 - Annual marine events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... application each year as required by 33 CFR part 100, subpart A, to the cognizant Coast Guard Sector Commander... Coast Guard, other Federal, state or local law enforcement, and any public or sponsor-provided vessels... agencies. Table 1 to 100.1102 1. Lake Havasu Winter Heat Water-Ski Race Sponsor National Water-ski...

  1. Tumor prevalence and biomarkers of exposure in brown bullhead (Ameiurus nebulosus) from Back River, Furnace Creek, and Tuckahoe River, Maryland

    USGS Publications Warehouse

    Pinkney, A.E.; Harshbarger, J.C.; May, E.B.; Melancon, M.J.

    2004-01-01

    Brown bullheads (Ameiurus nebulosus) were collected from 2 locations near Baltimore, Maryland, Back River and Furnace Creek, and 1 (reference) location, Tuckahoe River, to compare the prevalence of tumors (liver and skin) and visible skin lesions (fin erosion and abnormal barbels). Cytochrome P450 activity measured as ethoxyresorufin-O-deethylase, biliary PAH-like fluorescent metabolites, and fillet contaminant concentrations were determined as indicators of exposure in a randomly selected subset of the fish. There were no significant differences in liver tumor prevalence: Back River = 8% (4/50), Furnace Creek = 0% (0/50), and Tuckahoe River = 2.6% (1/39; p = 0.20, extension of Fishers exact test). Skin tumor prevalence was as follows: Furnace Creek = 12% (6/50), Back River = 8% (4/50), and Tuckahoe River = 0% (0/39; p = 0.063). In the Back River fish, there was a 40% (20/50) prevalence of fin erosion and a 28% (14/50) prevalence of abnormal (shortened, clubbed, or missing) barbels. Fin erosion was not observed in the other collections, and only 10% (5/50) of the Furnace Creek fish had abnormal barbels (p < 0.001 for both lesions). There were statistically significant differences in mean EROD activity, with levels in Furnace Creek and Back River fish approximately twice that found in Tuckahoe River fish. There were also significant differences in mean benzo(a)pyrene-like bile metabolite concentrations: the lowest mean was in the Tuckahoe River fish, 8 times higher in Furnace Creek fish, and 13 times higher in Back River fish. Of the 3 groups, the Back River bullheads appear to be most adversely affected by contaminant exposure because they had the highest prevalence of liver tumors, fin erosion, and abnormal barbels.

  2. Assessment of the "fish tumors or other deformities" beneficial use impairment in brown bullhead (Ameiurus nebulosus): I. Orocutaneous tumors

    USGS Publications Warehouse

    Blazer, V.S.; Rafferty, S.D.; Baumman, P.C.; Smith, S.B.; Obert, E.C.

    2009-01-01

    The "fish tumor or other deformities" beneficial use impairment (BUI) occurs at 9 of the 12 areas of concern (AOC) on Lake Erie. As point sources are mitigated and remediation occurs, AOC are faced with determining delisting criteria. The lack of standardized analyses for this BUI has confounded that process. For orocutaneous tumors, different criteria (presumptive tumors and/or abnormal barbels) and methodology (gross versus microscopic observations) have been used. Hence, this project evaluated tumors at numerous AOC and non-AOC sites and compared methodology. In 1998-2000 the prevalence of presumptive orocutaneous tumors and barbel abnormalities was compared in brown bullhead (Ameiurus nebulosus) collected at eight AOC. The Black (46.7%), Buffalo (29.3%), Cuyahoga (58.9%), and Detroit (26.5%) rivers and Presque Isle Bay (28.6%) had high prevalences of orocutaneous tumors, while the Niagara (10%), Maumee (3.9%) and Ashtabula (4.4%) rivers were lower. From 2002 to 2007 the prevalence of orocutaneous tumors at Presque Isle Bay was consistently near 30%. A variety of non-AOC sites, as potential reference sites, were also monitored during this time. By combining years and sites the prevalence of orocutaneous tumors in bullhead (age 2-12 years) at inland lakes was 6.3%, at Long Point Inner Bay was 8.7%, at other bays and harbors was 14.6% and at tributary sites was 12.5%. Overall, 93% of the raised lesions identified as presumptive tumors grossly were verified as neoplasms microscopically. The prevalence of orocutaneous tumors increased with age at both Presque Isle Bay and Long Point Inner Bay, the sites with the largest sample sizes.

  3. Assessment of the "fish tumors or other deformities" beneficial use impairment in brown bullhead (Ameiurus nebulosus): II. Liver neoplasia

    USGS Publications Warehouse

    Blazer, V.S.; Rafferty, S.D.; Baumman, P.C.; Smith, S.B.; Obert, E.C.

    2009-01-01

    Liver pathology of fishes, including neoplastic and preneoplastic lesions, is widely used as an indicator of exposure to anthropogenic contaminants. By definition, the "fish tumor or other deformities" beneficial use impairment (BUI) at Great Lakes Areas of Concern (AOC) includes neoplastic and preneoplastic liver lesions in brown bullhead (Ameiurus nebulosus) or suckers. Unfortunately, adequate guidelines for defining neoplastic and preneoplastic liver lesions or determining rates at unimpacted control sites were not provided and different criteria have been used. In some cases, only neoplastic changes were used to calculate tumor prevalence, in some both neoplastic and preneoplastic changes and in some it is difficult to determine which changes were included. Using standardized criteria, the prevalence of liver neoplasia was compared at eight AOC during 1998-2000. The Cuyahoga River had the highest prevalence (25.0%), while the Maumee River had the lowest (3.9%). The Buffalo (4.8%), Detroit (5.9%), Ashtabula (6.8%), Niagara (7.5%) and Black (8.9%) rivers were intermediate, as was Presque Isle Bay (7.1%). From 2002 to 2007 the prevalence of liver neoplasia at Presque Isle Bay ranged from a low of 2.1% (2002) to a high of 12.0% (2007). Non-AOC sites, as potential reference sites, also were monitored during this time. By combining years and sites, the prevalence of liver neoplasia in bullhead (aged 2 to 12 years) at inland lakes was 0.7%, at bays/harbors was 1.6% and at tributary sites was 4.1%. This is the same trend (inland lakes < bays/harbors < tributaries < Presque Isle Bay) noted for orocutaneous neoplasms.

  4. A comparison of {beta}-adrenoceptors and muscarinic cholinergic receptors in tissues of brown bullhead catfish (Ameiurus nebulosus) from the Black River and Old Woman Creek, Ohio

    SciTech Connect

    Steevens, J.A.; Baumann, P.C.; Jones, S.B.

    1996-09-01

    {beta}-Adrenoceptors ({beta}ARs) and muscarinic cholinergic receptors were measured in brain, gill, and heart tissues of brown bullhead catfish exposed to polycyclic aromatic hydrocarbons in the Black River, Ohio, USA, and were compared to values from Old Woman Creek, Ohio, a reference site. A decreased number of {beta}ARs were found in the gill from Black River fish, possibly indicating a compensatory response subsequent to chemical stress.

  5. Biochemistry Games: "AZ-Quiz" and "Jeopardy!"

    ERIC Educational Resources Information Center

    Rostejnska, Milada; Klimova, Helena

    2011-01-01

    "AZ-Quiz" and "Jeopardy!" are popular television shows and serve as the basis for in-class games designed to support and diversify chemistry instruction at the high school level. Both games were created in Microsoft PowerPoint, which is an easily accessible and controllable instrument that enables the creation of engaging animation. The use of…

  6. 76 FR 619 - Arizona Disaster #AZ-00014

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-05

    ... ADMINISTRATION Arizona Disaster AZ-00014 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a Notice of the Presidential declaration of a major disaster for Public Assistance Only for the... Disaster Assistance, U.S. Small Business Administration, 409 3rd Street, SW., Suite 6050, Washington,...

  7. Biochemistry Games: "AZ-Quiz" and "Jeopardy!"

    ERIC Educational Resources Information Center

    Rostejnska, Milada; Klimova, Helena

    2011-01-01

    "AZ-Quiz" and "Jeopardy!" are popular television shows and serve as the basis for in-class games designed to support and diversify chemistry instruction at the high school level. Both games were created in Microsoft PowerPoint, which is an easily accessible and controllable instrument that enables the creation of engaging animation. The use of

  8. Tank 241-AZ-101 tank characterization plan

    SciTech Connect

    Schreiber, R.D.

    1995-02-06

    The Defense Nuclear Facilities Safety Board has advised the DOE to concentrate the near-term sampling and analysis activities on identification and resolution of safety issues. The Data Quality Objective (DQO) process was chosen as a tool to be used in the resolution of safety issues. As a result, A revision in the Federal Facilities Agreement and Consent Order (Tri-Party Agreement) milestone M-44 has been made, which states that ``A Tank Characterization Plan (TCP) will also be developed for each double-shell tank (DST) and single-shell tank (SST) using the DQO process. Development of TCPs by the DQO process is intended to allow users to ensure their needs will be met and that resources are devoted to gaining only necessary information``. This document satisfies that requirement for Tank 241-AZ-101 (AZ-101) sampling activities. Tank AZ-101 is currently a non-Watch List tank, so the only DQOs applicable to this tank are the safety screening DQO and the compatibility DQO, as described below. The contents of Tank AZ-101, as of October 31, 1994, consisted of 3,630 kL (960 kgal) of dilute non-complexed waste and aging waste from PUREX (NCAW, neutralized current acid waste). Tank AZ-101 is expected to have two primary layers. The bottom layer is composed of 132 kL of sludge, and the top layer is composed of 3,500 kL of supernatant, with a total tank waste depth of approximately 8.87 meters.

  9. Tank 241-AZ-102 tank characterization plan

    SciTech Connect

    Schreiber, R.D.

    1995-02-06

    The Defense Nuclear Facilities Safety Board has advised the DOE to concentrate the near-term sampling and analysis activities on identification and resolution of safety issues. The Data Quality Objective (DQO) process was chosen as a tool to be used in the resolution of safety issues. As a result, a revision in the Federal Facilities Agreement and Consent Order (Tri-Party Agreement) milestone M-44 has been made, which states that ``A Tank Characterization Plan (TCP) will also be developed for each double-shell tank (DST) and single-shell tank (SST) using the DQO process ... Development of TCPs by the DQO process is intended to allow users to ensure their needs will be met and that resources are devoted to gaining only necessary information``. This document satisfies that requirement for tank 241-AZ-102 (AZ-102) sampling activities. Tank AZ-102 is currently a non-Watch List tank, so the only DQOs applicable to this tank are the safety screening DQO and the compatibility DQO, as described below. The current contents of Tank AZ-102, as of October 31, 1994, consisted of 3,600 kL (950 kgal) of dilute non-complexed waste and aging waste from PUREX (NCAW, neutralized current acid waste). Tank AZ-102 is expected to have two primary layers. The bottom layer is composed of 360 kL of sludge, and the top layer is composed of 3,240 kL of supernatant, with a total tank waste depth of approximately 8.9 meters.

  10. Egg Development of the Ussurian Bullhead Fish, Leiocassis ussuriensis (Pisces: Bagridae) and Morphological Development of Its Larvae and Juveniles

    PubMed Central

    Park, Jae-Min; Yim, Hu-Sun; Lee, Yong-Sik; Kim, Heung-Yun; Han, Kyeong-Ho

    2015-01-01

    This study was examined the ovogenesis of Ussurian bullhead, Leiocassis ussuriensis and the morphological development of its larvae and juveniles and to use the results as basic information for the preservation of species and resource enhancement. For artificial egg collection, human chorionic gonadotropin (HCG) was injected at a rate of 10 IU per gram of fish weight. During breeding period, water temperature maintained at 24.5~26.5°C (mean 25.0±0.05°C). The process of ovogenesis reached the two-cell stage in 50 minutes after fertilization. In 73 hours of fertilization the movement of the embryoid body became active state and the larvae began to hatch from the tail through the oolemma. Length of prelarvae were 6.33~6.50 mm long (mean 6.40±0.06 mm) just after hatching having yolk with their mouth not opened. After thirty eight days of hatching, juveniles were 30.6∼32.5 mm long (mean 31.5±0.65 mm). The color was dark yellowish brown throughout the entire body, and the number of caudal fin rays developed to thirty six perfectly. PMID:26973970

  11. Monitoring exposure of brown bullheads and benthic macroinvertebrates to sediment contaminants in the Ashtabula River before, during, and after remediation.

    PubMed

    Meier, John R; Lazorchak, James M; Mills, Marc; Wernsing, Paul; Baumann, Paul C

    2015-06-01

    In 2007, approximately 420,500 cubic meters of contaminated sediment were removed from the Ashtabula River by dredging. The primary objective of the present study was to monitor contaminant exposure in fish and macroinvertebrates before, during, and after dredging. This was done by measuring tissue concentrations of polychlorinated biphenyl (PCB) and polycyclic aromatic hydrocarbon (PAH) in brown bullhead catfish (Ameriurus nebulosa) and in benthic macroinvertebrates, assessing changes in DNA damage in fish liver and blood, and scoring external and histopathological lesions and anomalies in the fish. In surficial sediment PCBs and PAHs were also quantified in conjunction with the biological sampling. The results show a significant reduction in contaminant levels in both fish and macroinvertebrates following dredging, indicating the effectiveness of the remediation in reducing exposure of biota to the primary contaminants of concern. Similarly, DNA damage levels in fish collected from the Ashtabula River significantly declined following dredging; however, a similar reduction in DNA damage over time was seen in fish collected from a reference site (Conneaut Creek), making interpretation difficult. Macroinvertebrate PCB concentrations were reflective of the sediment concentrations in the areas where Hester-Dendy samplers were deployed for macroinvertebrate collection. The present study demonstrates that these methods can be used to evaluate and assess the effectiveness of remediation techniques at contaminated sediment sites. PMID:25565098

  12. Egg Development of the Ussurian Bullhead Fish, Leiocassis ussuriensis (Pisces: Bagridae) and Morphological Development of Its Larvae and Juveniles.

    PubMed

    Park, Jae-Min; Yim, Hu-Sun; Lee, Yong-Sik; Kim, Heung-Yun; Han, Kyeong-Ho

    2015-12-01

    This study was examined the ovogenesis of Ussurian bullhead, Leiocassis ussuriensis and the morphological development of its larvae and juveniles and to use the results as basic information for the preservation of species and resource enhancement. For artificial egg collection, human chorionic gonadotropin (HCG) was injected at a rate of 10 IU per gram of fish weight. During breeding period, water temperature maintained at 24.5~26.5°C (mean 25.0±0.05°C). The process of ovogenesis reached the two-cell stage in 50 minutes after fertilization. In 73 hours of fertilization the movement of the embryoid body became active state and the larvae began to hatch from the tail through the oolemma. Length of prelarvae were 6.33~6.50 mm long (mean 6.40±0.06 mm) just after hatching having yolk with their mouth not opened. After thirty eight days of hatching, juveniles were 30.6∼32.5 mm long (mean 31.5±0.65 mm). The color was dark yellowish brown throughout the entire body, and the number of caudal fin rays developed to thirty six perfectly. PMID:26973970

  13. Computer simulation of the leaching and washing of waste in tanks C-106, AY-102, AZ-101, and AZ-102

    SciTech Connect

    MacLean, G.T.

    1997-05-01

    The waste in underground storage tanks C-106, AY-102, AZ-101, and AZ-102 will be used to prepare feed material for the proposed high level waste vitrification demonstration plant at Hanford. A chemical process simulation computer program called the Environment Simulation Program (ESP) was used to estimate the compositions and quantities of this waste and the products after pretreatment processing. The amount of precipitated material in Tank C-106 predicted to be dissolved by sluicing is 27 wt.%. The amount of precipitated material predicted to be dissolved by mild leaching is about 30% for the C-106 and AY-102 combined waste and about 50% for AZ-101, and 35% for AZ-102 wastes. The predicted caustic solution raw material requirements for leaching are 158 m{sup 3} for C-106 and AY-102, 60 m{sup 3} for AZ-101, and 146 m{sup 3} for AZ-102, all as 50 wt.% NAOH.

  14. 16. Park Avenue streetscape, looking northwest AZ191 (Clifton Mineral Hot ...

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

    16. Park Avenue streetscape, looking northwest AZ-191 (Clifton Mineral Hot Springs Bath House) at center, AZ-193 (Presbyterian Church) at right. - Clifton Townsite, Confluence of Chase Creek & San Francisco River, Clifton, Greenlee County, AZ

  15. 15. View to the northwest along railroad tracks. AZ180 (Arizona ...

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

    15. View to the northwest along railroad tracks. AZ-180 (Arizona and New Mexico Railroad Passenger Depot) at left. In the background can be seen, left to right, AZ-178 (Arizona Copper Company Office), AZ-177 (Arizona Copper Company Library Hall), AZ-179 (Park Avenue Bridge) and AZ-183 (La Casa Grande). - Clifton Townsite, Confluence of Chase Creek & San Francisco River, Clifton, Greenlee County, AZ

  16. Assessment of Debris Flow Hazards, North Mountain, Phoenix, AZ

    NASA Astrophysics Data System (ADS)

    Reavis, K. J.; Wasklewicz, T. A.

    2014-12-01

    Urban sprawl in many western U.S. cities has expanded development onto alluvial fans. In the case of metropolitan Phoenix, AZ (MPA), urban sprawl has led to an exponential outward growth into surrounding mountainous areas and onto alluvial fans. Building on alluvial fans places humans at greater risk to flooding and debris flow hazards. Recent research has shown debris flows often supply large quantities of material to many alluvial fans in MPA. However, the risk of debris flows to built environments is relatively unknown. We use a 2D debris flow modeling approach, aided by high-resolution airborne LiDAR and terrestrial laser scanning (TLS) topographic data, to examine debris flow behavior in a densely populated portion of the MPA to assess the risk and vulnerability of debris flow damage to the built infrastructure. A calibrated 2D debris flow model is developed for a "known" recent debris flow at an undeveloped site in MPA. The calibrated model and two other model scenarios are applied to a populated area with historical evidence of debris flow activity. Results from the modeled scenarios show evidence of debris flow damage to houses built on the alluvial fan. Debris flow inundation is also evident on streets on the fan. We use housing values and building damage to estimate the costs assocaited with various modeled debris flow scenarios.

  17. Tank 241-AZ-101 and tank 241-AZ-102, airlift circulator operation vapor sampling and analysis plan

    SciTech Connect

    TEMPLETON, A.M.

    1999-06-02

    This sampling and analysis plan (SAP) identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements for vapor samples obtained during the operation of the tank 241-AZ-101 and 241-AZ-102 airlift circulators (ALCs). The purpose of the ALC operation is to support portions of the operational test procedure (OTP) for Project W-030 (OTP-W030-001) and to perform functional test in support of Project W-151. Project W-030 is the 241-A-702 ventilation upgrade project (241-AZ-702) and Project W-151 is the 241-AZ-101 Mixer Pump Test. The functional tests will check the operability of the tank 241-AZ-101 ALCs. Process Memo's No.2E98-082 and No.2E99-001 (LMHC 1999a, LMHC 1999b) direct the operation of the ALCs and the Industrial Hygiene monitoring respectively. A series of tests will be conducted in which the ALCs in tanks 241-AZ-101 and 241-AZ-102 will be operated at different air flow rates. Vapor samples will be obtained to determine constituents that may be present in the tank headspace during ALC operation at tanks 241-AZ-101 and 241-AZ-102 as the waste is disturbed. During the testing, vapor samples will be obtained from the headspace of tanks 241-AZ-101 and 241-AZ-102 via the unused port on the standard hydrogen monitoring system (SHMS). Results will be used to provide the waste feed delivery program with environmental air permitting data for tank waste disturbing activities. Because of radiological concerns, the samples will be filtered for particulates. It is recognized that this may remove some organic compounds.

  18. 702AZ aging waste ventilation facility year 2000 test procedure

    SciTech Connect

    Winkelman, W.D.

    1998-07-22

    This test procedure was developed to determine if the 702AZ Tank Ventilation Facility system is Year 2000 Compliant. The procedure provides detailed instructions for performing the operations necessary and documenting the results. This verification procedure will document that the 702AZ Facility Systems are year 2000 compliant and will correctly meet the criteria established in this procedure.

  19. ANALYSIS RESULTS FOR BUILDING 241 702-AZ A TRAIN

    SciTech Connect

    DUNCAN JB; FRYE JM; COOKE CA; LI SW; BROCKMAN FJ

    2006-12-13

    This report presents the analyses results for three samples obtained under RPP-PLAN-28509, Sampling and Analysis Plan for Building 241 702-AZ A Train. The sampling and analysis was done in response to problem evaluation request number PER-2004-6139, 702-AZ Filter Rooms Need Radiological Cleanup Efforts.

  20. 241-AZ Farm Annulus Extent of Condition Baseline Inspection

    SciTech Connect

    Engeman, Jason K.; Girardot, Crystal L.; Vazquez, Brandon J.

    2013-05-15

    This report provides the results of the comprehensive annulus visual inspection for tanks 241- AZ-101 and 241-AZ-102 performed in fiscal year 2013. The inspection established a baseline covering about 95 percent of the annulus floor for comparison with future inspections. Any changes in the condition are also included in this document.

  1. Tumor Prevalence and Biomarkers of Exposure and Response in Brown Bullheads (Ameiurus nebulosus) from the Tidal Potomac River Watershed

    USGS Publications Warehouse

    Pinkney, A.E.; Harshbarger, J.C.; May, E.B.; Melancon, M.J.

    2000-01-01

    Four groups of thirty brown bullheads (Ameiurus nebulosus) were collected from the tidal Potomac River watershed to survey tumor prevalence in relation to contaminant exposure. Fish were obtained from the Quantico embayment, near a Superfund site that released polychlorinated biphenyls (PCBs) and DDT compounds; Neabsco Creek,.a tributary with petroleum inputs from upstream areas and marinas; and the Anacostia River (both in spring and fall),where sediment is contaminated with polynuclear aromatic hydrocarbons (PAHs), PCBs, and organochlorine pesticides. Fish were also collected from the Tuckahoe River, on the Eastern Shore of Maryland, as a reference. Fish were necropsied and examined grossly and histopathologically for skin and liver neoplasms. Cytochrome P450 activity, bile PAH metabolites, and muscle organochlorine pesticide/PCB concentrations were determined in randomly selected individuals. There were significant differences among sites in liver tumor prevalence: Anacostia (spring)-50%, Anacostia (fall)-60%, Neabsco-17%, Quantico-7%, Tuckahoe-10%. Skin tumor prevalences were also significantly different: Anacostia (spring)-37%, Anacostia (fall)-10%, Neabsco-3%, Quantico-3%, Tuckahoe-0%. Tumor prevalences in Anacostia fish were comparable to those at contaminated sites in the Great Lakes. PAH concentrations were higher in Anacostia sediments than at the other sites and there were significantly higher concentrations of PAH metabolites in bile of the Anacostia fish. At present, there are insufficient data, however, to establish a cause-effect linkage with a particular class of contaminants. Tumor surveys in selected species are recommended for monitoring the status and remediation of Regions of Concern and other areas in the Chesapeake Bay watershed.

  2. Antizyme (AZ) regulates intestinal cell growth independent of polyamines.

    PubMed

    Ray, Ramesh M; Bhattacharya, Sujoy; Bavaria, Mitul N; Viar, Mary Jane; Johnson, Leonard R

    2014-09-01

    Since antizyme (AZ) is known to inhibit cell proliferation and to increase apoptosis, the question arises as to whether these effects occur independently of polyamines. Intestinal epithelial cells (IEC-6) were grown in control medium and medium containing 5 mM difluoromethylornithine (DFMO) to inhibit ODC, DFMO + 5 M spermidine (SPD), DFMO + 5 M spermine (SPM), or DFMO + 10 M putrescine (PUT) for 4 days and various parameters of growth were measured along with AZ levels. Cell counts were significantly decreased and mean doubling times were significantly increased by DFMO. Putrescine restored growth in the presence of DFMO. However, both SPD and SPM when added with DFMO caused a much greater inhibition of growth than did DFMO alone, and both of these polyamines caused a dramatic increase in AZ. The addition of SPD or SPM to media containing DFMO + PUT significantly inhibited growth and caused a significant increase in AZ. IEC-6 cells transfected with AZ-siRNA grew more than twice as rapidly as either control cells or those incubated with DFMO, indicating that removal of AZ increases growth in cells in which polyamine synthesis is inhibited as well as in control cells. In a separate experiment, the addition of SPD increased AZ levels and inhibited growth of cells incubated with DFMO by 50%. The addition of 10 mM asparagine (ASN) prevented the increase in AZ and restored growth to control levels. These results show that cell growth in the presence or absence of ODC activity and in the presence or absence of polyamines depends only on the levels of AZ. Therefore, the effects of AZ on cell growth are independent of polyamines. PMID:24930035

  3. Tomorrow's City.

    ERIC Educational Resources Information Center

    Jones, Emrys

    1979-01-01

    Examines several simple models of cities, discussing possible future changes in city design. The concepts of the megalopolis, linear city, tower block, imploded or miniaturized city, and dispersed city are described. (CS)

  4. Structural polymorphism in the L1 loop regions of human H2A.Z.1 and H2A.Z.2

    PubMed Central

    Horikoshi, Naoki; Sato, Koichi; Shimada, Keisuke; Arimura, Yasuhiro; Osakabe, Akihisa; Tachiwana, Hiroaki; Hayashi-Takanaka, Yoko; Iwasaki, Wakana; Kagawa, Wataru; Harata, Masahiko; Kimura, Hiroshi; Kurumizaka, Hitoshi

    2013-01-01

    The histone H2A.Z variant is widely conserved among eukaryotes. Two isoforms, H2A.Z.1 and H2A.Z.2, have been identified in vertebrates and may have distinct functions in cell growth and gene expression. However, no structural differences between H2A.Z.1 and H2A.Z.2 have been reported. In the present study, the crystal structures of nucleosomes containing human H2A.Z.1 and H2A.Z.2 were determined. The structures of the L1 loop regions were found to clearly differ between H2A.Z.1 and H2A.Z.2, although their amino-acid sequences in this region are identical. This structural polymorphism may have been induced by a substitution that evolutionally occurred at the position of amino acid 38 and by the flexible nature of the L1 loops of H2A.Z.1 and H2A.Z.2. It was also found that in living cells nucleosomal H2A.Z.1 exchanges more rapidly than H2A.Z.2. A mutational analysis revealed that the amino-acid difference at position 38 is at least partially responsible for the distinctive dynamics of H2A.Z.1 and H2A.Z.2. These findings provide important new information for understanding the differences in the regulation and functions of H2A.Z.1 and H2A.Z.2 in cells. PMID:24311584

  5. Tank 241-AZ-101 and Tank 241-AZ-102 Airlift Circulator Operation Vapor Sampling and Analysis Plan

    SciTech Connect

    TEMPLETON, A.M.

    1999-12-07

    This sampling and analysis plan (SAP) identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements for vapor samples obtained during the operation of the tank 241-AZ-101 and 241-AZ-102 airlift circulators (ALCs) and during the initial operation (''bump'') of the tank 241-AZ-101 mixer pumps. The purpose of the ALC operation is to support portions of the operational test procedure (OTP) for Project W-030 (OTP-W030-001) and to perform functional test in support of Project W-151. Project W-030 is the 241-A-702 ventilation upgrade project (241-142-702) and Project W-151 is the 241-AZ-101 Mixer Pump Test. The functional tests will check the operability of the tank 241-AZ-101 ALCs. Process Memo's No. 2E98-082 and No. 2E99-001 (LMHC 1999a, LMHC 1999b) direct the operation of the ALCs and the Industrial Hygiene monitoring respectively. A series of tests will be conducted in which the ALCs in tanks 241-AZ-101 and 241-AZ-102 will be operated at different air flow rates. Vapor samples will be obtained to determine constituents that may be present in the tank headspace during ALC operation at tanks 241-AZ-101 and 241-AZ-102 as the waste is disturbed. During the testing, vapor samples will be obtained from the headspace of tanks 241-AZ-101 and 241-AZ-102 via the unused port on the standard hydrogen monitoring system (SHMS). In addition the last two vapor samples will be collected from the headspace of tank 241-AZ-101 during the operation of the mixer pumps. Each mixer pump will be operated for approximately 5 minutes. Results will be used to provide the waste feed delivery program with environmental air permitting data for tank waste disturbing activities. Because of radiological concerns, the samples will be filtered for particulates. It is recognized that this may remove some organic compounds. The following sections provide the general methodology and procedures to be used in the preparation, retrieval, transport, analysis, and reporting of results from vapor samples retrieved during the ALC testing.

  6. Superplastic Properties of AZ31 and AZ31-1.0Y-1.3Sr Alloy Produced by Twin-Roll Casting and Sequential Hot Rolling

    NASA Astrophysics Data System (ADS)

    Ning, Huiyan; Yu, Yandong; Lin, Kai; Wen, Lihua; Liu, Chunxiang

    2015-12-01

    Superplastic mechanical properties of the AZ31 and AZ31-1.0Y-1.3Sr magnesium alloy sheets produced by twin-roll casting and sequential hot rolling (TRC) were investigated. The AZ31-1.0Y-1.3Sr alloy sheets with the thickness of 1 mm were prepared by twin-roll casting process, which exhibited finer equiaxed grain structure. Uniaxial tensile testing and gas blow forming on AZ31 and AZ31-1.0Y-1.3Sr magnesium alloy sheets were carried out. Results show that the superplastic mechanical properties of AZ31-1.0Y-1.3Sr alloys are better than those of AZ31 alloys at 400 C and the strain rate of 7 10-4/s. The addition of Y and Sr elements is helpful to improve the formability of AZ31 alloy. Grain boundary sliding plays a dominant role in superplastic forming.

  7. 75 FR 57327 - Environmental Impact Statement; Pinal County, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-20

    ... area that currently exceeds existing road capacity and is expected to continue to worsen with the....205, Highway Planning and Construction. The regulations implementing Executive Order 12372 regarding... Federal Highway Administration Environmental Impact Statement; Pinal County, AZ AGENCY: Federal...

  8. 75 FR 81190 - Television Broadcasting Services; Yuma, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-27

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 Television Broadcasting Services; Yuma, AZ AGENCY: Federal Communications Commission. ACTION: Dismissal. SUMMARY: The Commission dismisses the petition for rulemaking filed by...

  9. Caustic leaching of composite AZ-101/AZ-102 Hanford tank sludge

    SciTech Connect

    Rapko, B.M.; Wagner, M.J.

    1997-07-01

    To reduce the quantity (and hence the cost) of glass canisters needed for disposing of high-level radioactive wastes from the Hanford tank farms, pretreatment processes are needed to remove as much nonradioactive material as possible. This report describes the results of a laboratory-scale caustic leaching test performed on a composite derived from a combination of 241-AZ-101 and 241-AZ-102 Hanford Tank sludges. The goals of this FY 1996 test were to evaluate the effectiveness of caustic leaching on removing key components from the sludge and to evaluate the effectiveness of varying the free-hydroxide concentrations by incrementally increasing the free hydroxide concentration of the leach steps up to 3 {und M} free hydroxide. Particle-size analysis of the treated and untreated sludge indicated that the size and range of the sludge particles remained essentially unchanged by the caustic leaching treatment. Both before and after caustic leaching, a particle range of 0.2 {micro}m to 50 {micro}m was observed, with mean particle diameters of 8.5 to 9 {micro}m based on the volume distribution and mean particle diameters of 0.3 to 0.4 {micro}m based on the number distribution.

  10. Electroless Nickel Phosphorus Plating on AZ31

    NASA Astrophysics Data System (ADS)

    Shartal, Kh. M.; Kipouros, G. J.

    2009-04-01

    One of the major drawbacks to using magnesium parts in automotive applications is poor corrosion resistance, which can be improved with a nickel-boron coating placed on a nickel-phosphorus coating, which, in turn, is placed on a phosphate-permanganate conversion-coating layer produced on the magnesium alloy AZ31. This work reports on the determination of the optimum kinetic parameters for producing a coherent nickel-phosphorus coating using an electroless-procedure phosphate-permanganate conversion-coating layer and for studying the effects of the experimental variables of the electroless plating process on the phosphorus content, surface morphology, and structure of the electroless nickel-phosphorus (EN-P) coatings produced. Measurements of the plating rate as a function of experimental variables such as the compositions of the plating bath constituents, temperature, and pH were implemented using the weight-gain method; the phosphorus content of the EN-P coatings was measured using energy-dispersive spectroscopy (EDS) analysis. The surface morphology of the coating was examined using a scanning electron microscope (SEM); X-ray diffraction (XRD) was used to characterize the structure of each coating. An empirical rate law was determined for EN-P plating on a phosphate-permanganate conversion coating. It is found that the deposition rate of the EN-P coating increases by increasing the deposition temperature, the concentration of free nickel ions, and the concentration of hypophosphite ions in the plating bath. In addition, the deposition rate decreases by increasing both the plating bath pH and the concentration of citric acid in the plating bath.

  11. Determining VOC boundary values for simulations of Phoenix, AZ ozone with limited ambient measurements

    SciTech Connect

    Hyde, P.; Oliver, W.R.; Heisler, S.L.; Tran, K.

    1998-12-31

    For Urban Airshed Model simulations of ozone episodes in 1992 and 1996 for Phoenix, AZ, numerous attempts to better characterize boundary conditions were made. The early boundary values relied on concentrations from urban sites that were adjusted to rural values, and ended with background VOC monitoring 50 miles west of Phoenix. Early attempts at specifying lateral boundary values for VOC depended on adjusting central city concentrations to boundary values based on simultaneous measurements with a limited analytical suite of 20 samples at a single boundary location and at three locations in the central city in 1992. Although these boundary values were refined and revised, their values proved to be too high to give a realistic boundary contribution to metropolitan ozone. These boundary values were lowered by incorporating hourly wind directions. Wind from the urban area led to a higher VOC value at a boundary segment, while wind from the rural area led to a lower VOC value at the boundary segment. These wind-directional dependent, spatially-varying boundary values were used in the final UAM model validation for a March, 1997 report. Evidence that these values were still too high, however, prompted a test with data from the remote location of Hillside, AZ, 80 miles northwest of Phoenix. These data consisted of only 53 hydrocarbons and 10 aldehydes, with no measurement of ethene. Boundary values based on these data produced ozone concentrations about 5% lower than the rural-urban, wind-direction dependent scheme. A special sampling program, conducted in May and June, 1997 at a site 50 miles west of Phoenix, provided data, that, when combined with the full Hillside data set, were sufficient to calculate optimal boundary concentrations for an October, 1997 report.

  12. 12. Smelter site along Coronado Boulevard, looking east. AZ174(Arizona Copper ...

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

    12. Smelter site along Coronado Boulevard, looking east. AZ-174(Arizona Copper Company Smelter Blower House) near center of photograph. - Clifton Townsite, Confluence of Chase Creek & San Francisco River, Clifton, Greenlee County, AZ

  13. Age 55 or better: active adult communities and city planning.

    PubMed

    Trolander, Judith Ann

    2011-01-01

    Active adult, age-restricted communities are significant to urban history and city planning. As communities that ban the permanent residence of children under the age of nineteen with senior zoning overlays, they are unique experiments in social planning. While they do not originate the concept of the common interest community with its shared amenities, the residential golf course community, or the gated community, Sun Cities and Leisure Worlds do a lot to popularize those physical planning concepts. The first age-restricted community, Youngtown, AZ, opened in 1954. Inspired by amenity-rich trailer courts in Florida, Del Webb added the active adult element when he opened Sun City, AZ, in 1960. Two years later, Ross Cortese opened the first of his gated Leisure Worlds. By the twenty-first century, these lifestyle communities had proliferated and had expanded their appeal to around 18 percent of retirees, along with influencing the design of intergenerational communities. PMID:22175080

  14. Genetic diversity and comparative analysis of gene expression between Heterorhabditis bacteriophora Az29 and Az36 isolates: uncovering candidate genes involved in insect pathogenicity.

    PubMed

    Hao, You-Jin; Montiel, Rafael; Lucena, Miguel A; Costa, Miguel; Simoes, Nelson

    2012-02-01

    Entomopathogenic nematode Heterorhabditis bacteriophora Az29 and Az36 isolates with different virulence against Popillia unipuncta and soil survival time were isolated from the Azorean archipelago (Portugal) and used for the study. RAPD analysis revealed a very low-level of genetic diversity (GD(axenic Az36 isolate)(axenic Az29 isolate)=0.23380.0541) between axenic Az29 and Az36 isolates, and a relative low-level of diversity (GD(Az36 isolate)(Az29 isolate)=0.33660.0471) between Az29 and Az36 isolates. To unravel the molecular differences, a suppressive subtractive hybridization library was constructed from the parasitic stage. Assembling 150 high quality ESTs produced 70 singletons and 17 contigs. BLAST analysis revealed that 48 ESTs showed significant similarity to known protein and 39 ESTs had no significant hits in the database, perhaps representing novel genes. Functional annotation revealed some of these genes to be involved in metabolism, cellular process and signaling, information storage and processing, stress response and host-parasite interactions. Genes with a role in the parasitism process were identified including lectin, metalloprotease, enolase, chitinase, surface-associated antigen, and as well as genes (aquaporin, Hsp70A, Hsp10 and Hsp20) essential for stresses tolerance. The work described here provides the molecular data necessary for investigating the fundamental molecular aspects of host-parasite interactions. Future investigations should be focused on determining the molecular mechanism of those genes in entomopathogenic nematode life cycle. PMID:22206770

  15. AZ-101 Mixer Pump Test Qualification Test Procedures (QTP)

    SciTech Connect

    THOMAS, W.K.

    2000-01-10

    Describes the Qualification test procedure for the AZ-101 Mixer Pump Data Acquisition System (DAS). The purpose of this Qualification Test Procedure (QTP) is to confirm that the AZ-101 Mixer Pump System has been properly programmed and hardware configured correctly. This QTP will test the software setpoints for the alarms and also check the wiring configuration from the SIMcart to the HMI. An Acceptance Test Procedure (ATP), similar to this QTP will be performed to test field devices and connections from the field.

  16. Arizonans on Edge...So Why Not Involved? AZ Views. Volume 2, Issue 1

    ERIC Educational Resources Information Center

    Morrison Institute for Public Policy, Arizona State University, 2009

    2009-01-01

    What a difference a year makes. In June 2008, "AZ Views" reported that "Arizonans have a strong sense of job security, despite the national economic slump and the state's budget crisis." That is no longer true, as this edition of "AZ Views" shows, and Arizona's economic situation arguably is the best example of the worst case.This issue of "AZ

  17. 76 FR 45178 - Modification of Class D and E Airspace; Fort Huachuca, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-28

    ... Federal Aviation Administration 14 CFR Part 71 Modification of Class D and E Airspace; Fort Huachuca, AZ... Class D and Class E airspace at Fort Huachuca, AZ, to accommodate aircraft departing and arriving under... Register a notice of proposed rulemaking to modify controlled airspace at Fort Huachuca, AZ (76 FR...

  18. 75 FR 39146 - Amendment of Class D and E Airspace; Yuma, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-08

    ... modify Class D and E airspace at Yuma, AZ (75 FR 14382). Interested parties were invited to participate... Federal Aviation Administration 14 CFR Part 71 Amendment of Class D and E Airspace; Yuma, AZ AGENCY... Class D and Class E airspace in the Yuma, AZ, area to accommodate aircraft arriving and...

  19. 19. View to the north of Riverside Avenue. AZ196(J. C. ...

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

    19. View to the north of Riverside Avenue. AZ-196(J. C. Gatti House) at left Part of AZ-197 (Shannon Copper Company Store) can be seen in group of buildings at right - Clifton Townsite, Confluence of Chase Creek & San Francisco River, Clifton, Greenlee County, AZ

  20. The evolutionary differentiation of two histone H2A.Z variants in chordates (H2A.Z-1 and H2A.Z-2) is mediated by a stepwise mutation process that affects three amino acid residues

    PubMed Central

    Eirn-Lpez, Jos M; Gonzlez-Romero, Rodrigo; Dryhurst, Deanna; Ishibashi, Toyotaka; Ausi, Juan

    2009-01-01

    Background The histone H2A family encompasses the greatest number of core histone variants of which the replacement variant H2A.Z is currently one of the most heavily studied. No clear mechanism for the functional variability that H2A.Z imparts to chromatin has yet been proposed. While most of the past studies have referred to H2A.Z generically as a single protein, in vertebrates it is a mixture of two protein forms H2A.Z-1 (previously H2A.Z) and H2A.Z-2 (previously H2A.F/Z or H2A.V) that differ by three amino acids. Results We have performed an extensive study on the long-term evolution of H2A.Z across metazoans with special emphasis on the possible selective mechanisms responsible for the differentiation between H2A.Z-1 and H2A.Z-2. Our results reveal a common origin of both forms early in chordate evolution. The evolutionary process responsible for the differentiation involves refined stepwise mutation change within the codons of the three differential residues. This eventually led to differences in the intensity of the selective constraints acting upon the different H2A.Z forms in vertebrates. Conclusion The results presented in this work definitively reveal that the existence of H2A.Z-1 and H2A.Z-2 is not a whim of random genetic drift. Our analyses demonstrate that H2A.Z-2 is not only subject to a strong purifying selection but it is significantly more evolutionarily constrained than H2A.Z-1. Whether or not the evolutionary drift between H2A.Z-1 and H2A.Z-2 has resulted in a functional diversification of these proteins awaits further research. Nevertheless, the present work suggests that in the process of their differently constrained evolutionary pathways, these two forms may have acquired new or complementary functions. PMID:19193230

  1. Education Cities

    ERIC Educational Resources Information Center

    Shaked, Haim

    2014-01-01

    In recent years, several cities in Israel have labeled themselves "Education Cities," concentrating on education as their central theme. Employing qualitative techniques, this article aims to describe, define, and conceptualize this phenomenon as it is being realized in three such cities. Findings show that Education Cities differ from

  2. Education Cities

    ERIC Educational Resources Information Center

    Shaked, Haim

    2014-01-01

    In recent years, several cities in Israel have labeled themselves "Education Cities," concentrating on education as their central theme. Employing qualitative techniques, this article aims to describe, define, and conceptualize this phenomenon as it is being realized in three such cities. Findings show that Education Cities differ from…

  3. 75 FR 883 - Environmental Impact Statement; Maricopa County, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-06

    ... Federal Highway Administration Environmental Impact Statement; Maricopa County, AZ AGENCY: Federal Highway... public that an Environmental Impact Statement will be prepared for a proposed highway project in Maricopa... prepare an Environmental Impact Statement (EIS) on proposed operational improvements to the Interstate...

  4. 75 FR 19246 - Safety Zone; Desert Storm, Lake Havasu, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-14

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Desert Storm, Lake Havasu, AZ AGENCY: Coast... zone within the Thompson Bay region of the navigable waters of the Colorado River in Lake Havasu, Lake... Purpose The Lake Racer LLC is sponsoring the Desert Storm Charity Poker Run and Exhibition Run, which...

  5. 75 FR 22697 - Safety Zone; APBA National Tour, Parker, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-30

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; APBA National Tour, Parker, AZ AGENCY..., Arizona for the APBA National Tour. This temporary safety zone is necessary to provide for the safety of... and Purpose RPM Racing Enterprises is sponsoring the APBA National Tour, which is held in...

  6. Mixer pump test plan for double shell tank AZ-101

    SciTech Connect

    STAEHR, T.W.

    1999-05-12

    Mixer pump systems have been chosen as the method for retrieval of tank wastes contained in double shell tanks at Hanford. This document describes the plan for testing and demonstrating the ability of two 300 hp mixer pumps to mobilize waste in tank AZ-101. The mixer pumps, equipment and instrumentation to monitor the test were installed by Project W-151.

  7. 78 FR 17743 - Navajo Nation Disaster #AZ-00026

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-22

    ... ADMINISTRATION Navajo Nation Disaster AZ-00026 AGENCY: U.S. Small Business Administration. ACTION: Notice... for the Navajo Nation (FEMA-4104- DR), dated 03/05/2013. Incident: Severe Freeze. Incident Period: 12...: Primary Areas: Navajo Nation and Associated Lands. The Interest Rates are: For Physical Damage:...

  8. 77 FR 10649 - Modification of Class E Airspace; Douglas, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-23

    ... proposed rulemaking to amend controlled airspace at Douglas, AZ (76 FR 78180). Interested parties were... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does.... 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in...

  9. 78 FR 3877 - Radio Broadcasting Services; Peach Springs, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-17

    ... COMMISSION 47 CFR Part 73 Radio Broadcasting Services; Peach Springs, AZ AGENCY: Federal Communications... filing procedures for comments, see 47 CFR 1.415 and 1.420. List of Subjects in 47 CFR Part 73 Radio, Radio broadcasting. Federal Communications Commission. Nazifa Sawez, Assistant Chief, Audio...

  10. 76 FR 18378 - Amendment of Class E Airspace; Taylor, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-04

    .... Issued in Seattle, Washington, on March 21, 2011. Christine Mellon, Acting Manager, Operations Support... U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71... amend controlled airspace at Taylor, AZ (76 FR 3570). Interested parties were invited to participate...

  11. 75 FR 19250 - Safety Zone; BWRC Spring Classic, Parker, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-14

    ... temporary safety zone include all areas of the Colorado River from Headgate Dam to 0.5 miles north of the... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; BWRC Spring Classic, Parker, AZ AGENCY... safety zone within the Lake Moolvalya region of the navigable waters of the Colorado River in...

  12. 76 FR 45177 - Establishment of Class E Airspace; Kayenta, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-28

    ... Federal Register a notice of proposed rulemaking to establish controlled airspace at Kayenta, AZ (76 FR... a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979.... 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in...

  13. 75 FR 57383 - Modification of Class E Airspace; Willcox, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-21

    ... Federal Register a notice of proposed rulemaking to amend controlled airspace at Willcox, AZ (75 FR 33561... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a... follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E. O. 10854, 24 FR 9565, 3 CFR, 1959-1963...

  14. 76 FR 57634 - Establishment of Class E Airspace; Chinle, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-16

    ... Federal Register a notice of proposed rulemaking to establish controlled airspace at Chinle, AZ (76 FR... a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979.... 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in...

  15. Influence of artificial biological fluid composition on the biocorrosion of potential orthopedic Mg-Ca, AZ31, AZ91 alloys.

    PubMed

    Gu, X N; Zheng, Y F; Chen, L J

    2009-12-01

    The electrochemical behavior of potential orthopedic Mg-Ca, AZ31 and AZ91 alloys was studied in Hank's solution, Dulbecco's Modified Eagle's Medium (DMEM) and serum-containing medium (DMEM adding 10% fetal bovine serum (DMEM+FBS)) over a 7 day immersion period. The biocorrosion of the above three alloys for various immersion time intervals was investigated by linear polarization and electrochemical impedance spectroscopy (EIS). After 7 day immersion, potentiodynamic polarization tests were carried out and the surface morphologies of experimental samples were examined by scanning electron microscopy (SEM) observation complemented by energy-disperse spectrometer (EDS) analysis. It was shown that the corrosion of magnesium alloys was influenced by the composition of the solution. The results indicated that chloride ion could reduce the corrosion resistance and the hydrocarbonate ions could induce rapid surface passivation. The adsorbed amino acid on the experimental magnesium alloys' surface increased their polarization resistance and reduced current densities. The influence of the serum protein on corrosion was found to be associated with the magnesium alloy compositions. A Mg-Ca alloy exhibited an increased corrosion rate in the presence of serum protein. An AZ31 alloy showed an increased corrosion rate in DMEM+FBS in the initial 3 day immersion and the corrosion rate decreased thereafter. An AZ91 alloy, with high Al content, showed a reduced corrosion rate with the addition of FBS into DMEM. PMID:19966381

  16. 77 FR 19927 - Amendment of Class E Airspace; Willcox, AZ, and Revocation of Class E Airspace; Cochise, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-03

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION...-4537. SUPPLEMENTARY INFORMATION: History On January 10, 2012, the FAA published in the Federal Register... controlled airspace designation at Cochise, AZ (77 FR 1428). Interested parties were invited to...

  17. Superplastic Properties of AZ31 and AZ31-1.0Y-1.3Sr Alloy Produced by Twin-Roll Casting and Sequential Hot Rolling

    NASA Astrophysics Data System (ADS)

    Ning, Huiyan; Yu, Yandong; Lin, Kai; Wen, Lihua; Liu, Chunxiang

    2016-02-01

    Superplastic mechanical properties of the AZ31 and AZ31-1.0Y-1.3Sr magnesium alloy sheets produced by twin-roll casting and sequential hot rolling (TRC) were investigated. The AZ31-1.0Y-1.3Sr alloy sheets with the thickness of 1 mm were prepared by twin-roll casting process, which exhibited finer equiaxed grain structure. Uniaxial tensile testing and gas blow forming on AZ31 and AZ31-1.0Y-1.3Sr magnesium alloy sheets were carried out. Results show that the superplastic mechanical properties of AZ31-1.0Y-1.3Sr alloys are better than those of AZ31 alloys at 400 °C and the strain rate of 7 × 10-4/s. The addition of Y and Sr elements is helpful to improve the formability of AZ31 alloy. Grain boundary sliding plays a dominant role in superplastic forming.

  18. Coating pretreatment for Mg alloy AZ91D

    NASA Astrophysics Data System (ADS)

    Yang, H. Y.; Chen, X. B.; Guo, X. W.; Wu, G. H.; Ding, W. J.; Birbilis, N.

    2012-05-01

    Coating defects and coating failure upon Mg alloy AZ91D are usually due to non-uniform coating growth, which is intrinsically caused by the microstructural heterogeneity of the Mg substrate. This is the case for both conversion coatings and electroplated (incl. electroless) coatings. In the present study, coating pretreatment for the purpose of tailoring surface chemistry on AZ91D was studied. Pretreatments to control ?-phase morphology and surface homogeneity include alkaline conditioning and acid activation in four different non-toxic (F-free) acid solutions: H3PO4, HNO3, HCl and C6H8O7. The results show that careful pretreatment can do all of the following: modify surface roughness; remove ?-phase; modify solid solution chemistry; and most importantly, tailor the anodic/cathodic character of the surface. This allows surface pretreatment to be customized to optimize the subsequent coating. The influence of different acids was shown to be marked.

  19. The Corrosion Protection of Magnesium Alloy AZ31B

    NASA Technical Reports Server (NTRS)

    Danford, M. D.; Mendrek, M. J.; Mitchell, M. L.; Torres, P. D.

    1997-01-01

    Corrosion rates for bare and coated Magnesium alloy AZ31B have been measured. Two coatings, Dow-23(Trademark) and Tagnite(Trademark), have been tested by electrochemical methods and their effectiveness determined. Electrochemical methods employed were the scanning reference electrode technique (SRET), the polarization resistance technique (PR) and the electrochemical impedance spectroscopy technique (EIS). In addition, general corrosion and stress corrosion methods were employed to examine the effectiveness of the above coatings in 90 percent humidity. Results from these studies are presented.

  20. Formability study of magnesium alloy AZ31B

    NASA Astrophysics Data System (ADS)

    Liu, Z. G.; Lasne, P.; Massoni, E.

    2011-08-01

    The main aim of this paper is to study the formability of the AZ31B magnesium alloy at various temperature and strain rates. The tensile tests are performed to describe the rheological behavior of material, and the constitutive law is identified with Voce law [1], which contains a softening item. The law is proved effectiveness by fitting the equation with the experimental data. Nakazima experiments with hemispherical punch have been performed at CEMEF on a hydraulic testing machine. Six strain paths are selected by performing various sample geometries [2]. The AramisOptical strain measurement system has been used to obtain principle forming limit strain. The Forming Limit Diagram (FLD) is obtained by the critical point on the specimen surface at various temperatures. It is shown that the forming limit curve is higher at high temperature. Based on the Voce law model, finite element simulations of deep drawing test have been done with the commercial finite element code FORGE® in order to investigate the feasibility of hot stamping process for AZ31. In the simulation, the punch load and the thickness distributions have been studied. Meanwhile, the cross-shaped cup deep drawing simulations have been conducted with the data provided in the conference Website. The similar conclusion are obtained that the formability of AZ31 improve at high temperature and the simulation is effective in hot stamping processing. The study results are helpful for the application of the stamping technology for the magnesium alloy sheet [3].

  1. Reorganization of Damaged Chromatin by the Exchange of Histone Variant H2A.Z-2

    SciTech Connect

    Nishibuchi, Ikuno; Suzuki, Hidekazu; Kinomura, Aiko; Sun, Jiying; Liu, Ning-Ang; Horikoshi, Yasunori; Shima, Hiroki; Kusakabe, Masayuki; Harata, Masahiko; Fukagawa, Tatsuo; Ikura, Tsuyoshi; Ishida, Takafumi; Nagata, Yasushi; Tashiro, Satoshi

    2014-07-15

    Purpose: The reorganization of damaged chromatin plays an important role in the regulation of the DNA damage response. A recent study revealed the presence of 2 vertebrate H2A.Z isoforms, H2A.Z-1 and H2A.Z-2. However, the roles of the vertebrate H2A.Z isoforms are still unclear. Thus, in this study we examined the roles of the vertebrate H2A.Z isoforms in chromatin reorganization after the induction of DNA double-strand breaks (DSBs). Methods and Materials: To examine the dynamics of H2A.Z isoforms at damaged sites, we constructed GM0637 cells stably expressing each of the green fluorescent protein (GFP)-labeled H2A.Z isoforms, and performed fluorescence recovery after photobleaching (FRAP) analysis and inverted FRAP analysis in combination with microirradiation. Immunofluorescence staining using an anti-RAD51 antibody was performed to study the kinetics of RAD51 foci formation after 2-Gy irradiation of wild-type (WT), H2A.Z-1- and H2A.Z-2-deficient DT40 cells. Colony-forming assays were also performed to compare the survival rates of WT, H2A.Z-1-, and H2A.Z-2-deficient DT40 cells with control, and H2A.Z-1- and H2A.Z-2-depleted U2OS cells after irradiation. Results: FRAP analysis revealed that H2A.Z-2 was incorporated into damaged chromatin just after the induction of DSBs, whereas H2A.Z-1 remained essentially unchanged. Inverted FRAP analysis showed that H2A.Z-2 was released from damaged chromatin. These findings indicated that H2A.Z-2 was exchanged at DSB sites immediately after the induction of DSBs. RAD51 focus formation after ionizing irradiation was disturbed in H2A.Z-2-deficient DT40 cells but not in H2A.Z-1-deficient cells. The survival rate of H2A.Z-2-deficient cells after irradiation was lower than those of WT and H2A.Z-1- DT40 cells. Similar to DT40 cells, H2A.Z-2-depleted U2OS cells were also radiation-sensitive compared to control and H2A.Z-1-depleted cells. Conclusions: We found that vertebrate H2A.Z-2 is involved in the regulation of the DNA damage response at a very early stage, via the damaged chromatin reorganization required for RAD51 focus formation.

  2. XPS study of the surface chemistry on AZ31 and AZ91 magnesium alloys in dilute NaCl solution

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Shinohara, Tadashi; Zhang, Bo-Ping

    2010-08-01

    The surface chemistry on AZ31 and AZ91 magnesium alloys was characterized by X-ray photoelectron spectroscopy (XPS) in the corrosion and the passivation zones. In the corrosion zone, the presence of Mg(OH) 2 and MgCO 3 species was found in the outer surface, whereas, in the inner layer, the co-existence of Mg(OH) 2, MgO and MgCO 3 species was observed for both alloys. The presence of Al 3+ in the surface electrolyte to form Al 2O 3/Al(OH) 3 and the formation of carbonate product provide a better passivation on the surfaces and retard the chloride-induced corrosion on the materials in the passivation zone.

  3. 8-Hydroxy-2{prime}-deoxyguanosine (8-OH-dG): A biomarker of oxidative damage in yellow bullheads chronically exposed to low-level radiation

    SciTech Connect

    McCreedy, C.D.; Glickman, L.T.; Jagoe, C.H.

    1995-12-31

    8-hydroxy-2{prime}-deoxyguanosine (8-OH-dG), an oxidation product of the nucleotide deoxyguanosine (dG) was used as a biomarker to assess oxidative damage in brain and gill tissues of yellow bullhead catfish (Ameiurus natalis; n = 18) inhabiting an abandoned reactor reservoir contaminated with low levels of {sup d137}Cs (Pond B, Savannah River Site, SC). DNA was isolated by chloroform-isoamyl extraction, enzymatically digested with Nuclease P1/Calf Intestinal Phosphatase, and analyzed by HPLC with electrochemical detection.Length, weight, age, condition and muscle {sup 137}Cs activity of each fish were also determined. Concentrations of 8-OH-dG were greater in brain than in gill tissues. 8-OH-dG in gill tissues decreased as condition of fish increased, but as age increased, the effect of condition declined. Brain 8-OH-dG concentration was not related to age or condition of fish, but was greater in females and the interaction between gender and {sup 137}Cs was significant. Brain 8-OH-dG was positively associated with muscle {sup 137}Cs concentration among females, but was unrelated to {sup 137}Cs concentration in males. At lower {sup 137}Cs concentrations, females tended to have fewer oxidative DNA adducts in brian than did males. Deposition of somatic lipids into eggs may provide females some anti-oxidant benefit by diminishing the contribution of lipid peroxidation to DNA damage. 8-OH-dG is a sensitive biomarker of low-level radiation exposure, however, its application in fish requires consideration of factors such as gender, age, body-condition, and the tissue type sampled.

  4. Plasma electrolytic oxidation coating on AZ91 magnesium alloy modified by neodymium and its corrosion resistance

    NASA Astrophysics Data System (ADS)

    Song, Y. L.; Liu, Y. H.; Yu, S. R.; Zhu, X. Y.; Wang, Q.

    2008-03-01

    Ceramic coatings on the surfaces of Mg-9Al-1Zn (AZ91) magnesium alloy and Mg-9Al-1Zn-1Nd magnesium alloy (AZ91 magnesium alloy modified by neodymium, named as AZ91Nd in this paper) are synthesized in aluminate electrolyte by plasma electrolytic oxidation (PEO) process, respectively. X-ray diffraction and X-ray photoelectron spectroscopy analyses show the PEO coating on the Mg-9Al-1Zn-1Nd alloy comprises not only MgO and Al 2O 3, which are found in the coating on the AZ91 alloy, but also a trace amount of Nd 2O 3. Microstructure observations indicate the addition of Nd can decrease the sizes of ? phases and form Al 2Nd intermetallics in the AZ91 alloy. The fine ? phases can effectively restrain the formation of unclosed-holes and greatly decrease the sizes of pores in the coating during the PEO process. In addition, the Al 2Nd intermetallics can be completely covered due to the lateral growth of the PEO coatings formed on the ? and ? phases. As a result, the coating on the AZ91Nd alloy possesses a dense microstructure compared with that on the AZ91 alloy. The following corrosion tests indicate the corrosion resistance of the PEO coating on the AZ91Nd alloy is evidently higher than that of the PEO coating on the AZ91 alloy.

  5. Tank 241-AZ-102 Privatization Push Mode Core Sampling and Analysis Plan

    SciTech Connect

    RASMUSSEN, J.H.

    2000-05-23

    This sampling and analysis plan (SAP) identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements for samples obtained from tank 241-AZ-102.

  6. 241-AZ Tank Farm Construction Extent of Condition Review for Tank Integrity

    SciTech Connect

    Barnes, Travis J.; Boomer, Kayle D.; Gunter, Jason R.; Venetz, Theodore J.

    2013-07-30

    This report provides the results of an extent of condition construction history review for tanks 241-AZ-101 and 241-AZ-102. The construction history of the 241-AZ tank farm has been reviewed to identify issues similar to those experienced during tank AY-102 construction. Those issues and others impacting integrity are discussed based on information found in available construction records, using tank AY-102 as the comparison benchmark. In the 241-AZ tank farm, the second DST farm constructed, both refractory quality and tank and liner fabrication were improved.

  7. Sensitivity of summer climate to anthropogenic land-cover change over the Greater Phoenix, AZ, region

    USGS Publications Warehouse

    Georgescu, M.; Miguez-Macho, G.; Steyaert, L.T.; Weaver, C.P.

    2008-01-01

    This work evaluates the first-order effect of land-use/land-cover change (LULCC) on the summer climate of one of the nation's most rapidly expanding metropolitan complexes, the Greater Phoenix, AZ, region. High-resolution-2-km grid spacing-Regional Atmospheric Modeling System (RAMS) simulations of three "wet" and three "dry" summers were carried out for two different land-cover reconstructions for the region: a circa 1992 representation based on satellite observations, and a hypothetical land-cover scenario where the anthropogenic landscape of irrigated agriculture and urban pixels was replaced with current semi-natural vegetation. Model output is evaluated with respect to observed air temperature, dew point, and precipitation. Our results suggest that development of extensive irrigated agriculture adjacent to the urban area has dampened any regional-mean warming due to urbanization. Consistent with previous observationally based work, LULCC produces a systematic increase in precipitation to the north and east of the city, though only under dry conditions. This is due to a change in background atmospheric stability resulting from the advection of both warmth from the urban core and moisture from the irrigated area. ?? 2008 Elsevier Ltd. All rights reserved.

  8. Modelling of Superplastic Forming of AZ31 Magnesium Alloy

    SciTech Connect

    Giuliano, G.

    2011-01-17

    In this study the constitutive equation of the superplastic AZ31 magnesium-based alloy is modelled by the power law relationship between the stress, the strain and the strain-rate and an accurate procedure for determining the constants of the material is presented. Moreover, the problem of optimizing the pressure-time load curve of a free forming process is investigated and resolved by means of a pressure jump forming process. The experimental tests, carried out to support the finite-element modelling, have shown good agreement between the numerical results and the experimental data.

  9. Mixer pump test plan for double shell tank AZ-101

    SciTech Connect

    Symons, G.A.; Staehr, T.W., Westinghouse Hanford

    1996-06-01

    Westinghouse Hanford Company has undertaken the task to develop and demonstrate a method of retrieval for double-shell tank (DST)waste. Mixer pumps were chosen as the planned method of retrieval for the DSTs, based on engineering technology studies,past experience with hydraulic sluicing at the Hanford Site, and experience with mixer pumps at the Westinghouse Savannah River Site. This document outlines a test plan to demonstrate the ability of two 300 hp mixer pumps installed in the AZ-101 tank to mobilize waste.

  10. Atypical Cities

    ERIC Educational Resources Information Center

    DiJulio, Betsy

    2011-01-01

    In this creative challenge, Surrealism and one-point perspective combine to produce images that not only go "beyond the real" but also beyond the ubiquitous "imaginary city" assignment often used to teach one-point perspective. Perhaps the difference is that in the "atypical cities challenge," an understanding of one-point perspective is a means

  11. Atypical Cities

    ERIC Educational Resources Information Center

    DiJulio, Betsy

    2011-01-01

    In this creative challenge, Surrealism and one-point perspective combine to produce images that not only go "beyond the real" but also beyond the ubiquitous "imaginary city" assignment often used to teach one-point perspective. Perhaps the difference is that in the "atypical cities challenge," an understanding of one-point perspective is a means…

  12. CONCENTRATIONS OF PESTICIDE FROM DERMAL SURFACES: A COMPARISON OF NHEXAS & AZ BORDER SAMPLES

    EPA Science Inventory

    NHEXAS-AZ was a statewide survey designed to gather data on the distributions of exposure from various media. Results of intensive sampling were obtained from 179 homes. Border-AZ was a similar study focusing on homes within 40 km of the Arizona-Mexico Border; similar results...

  13. 75 FR 14382 - Proposed Amendment of Class D and E Airspace; Yuma, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-25

    ... Federal Aviation Administration 14 CFR Part 71 Proposed Amendment of Class D and E Airspace; Yuma, AZ...: This action proposes to modify Class D and Class E airspace in the Yuma, AZ, area. Additional... Regulations (14 CFR) part 71 by modifying Class D airspace, and Class E airspace designated as surface area...

  14. H2A.Z.1 Monoubiquitylation Antagonizes BRD2 to Maintain Poised Chromatin in ESCs.

    PubMed

    Surface, Lauren E; Fields, Paul A; Subramanian, Vidya; Behmer, Russell; Udeshi, Namrata; Peach, Sally E; Carr, Steven A; Jaffe, Jacob D; Boyer, Laurie A

    2016-02-01

    Histone variant H2A.Z occupies the promoters of active and poised, bivalent genes in embryonic stem cells (ESCs) to regulate developmental programs, yet how it contributes to these contrasting states is poorly understood. Here, we investigate the function of H2A.Z.1 monoubiquitylation (H2A.Z.1ub) by mutation of the PRC1 target residues (H2A.Z.1(K3R3)). We show that H2A.Z.1(K3R3) is properly incorporated at target promoters in murine ESCs (mESCs), but loss of monoubiquitylation leads to de-repression of bivalent genes, loss of Polycomb binding, and faulty lineage commitment. Using quantitative proteomics, we find that tandem bromodomain proteins, including the BET family member BRD2, are enriched in H2A.Z.1 chromatin. We further show that BRD2 is gained at de-repressed promoters in H2A.Z.1(K3R3) mESCs, whereas BRD2 inhibition restores gene silencing at these sites. Together, our study reveals an antagonistic relationship between H2A.Z.1ub and BRD2 to regulate the transcriptional balance at bivalent genes to enable proper execution of developmental programs. PMID:26804911

  15. 77 FR 25741 - Notice of Inventory Completion: Arizona State Museum, University of Arizona, Tucson, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-01

    ... Repatriation Act (NAGPRA), 25 U.S.C. 3003, of the completion of an inventory of human remains and associated... Maricopa County, AZ. The excavations were conducted by the Gila Pueblo Foundation. In December 1950, the... Pinal County, AZ. The excavations were conducted by the Gila Pueblo Foundation. In December 1950,...

  16. 78 FR 17869 - Safety Zone; Desert Storm Shootout; Lake Havasu, Lake Havasu City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-25

    ... FR Federal Register NPRM Notice of Proposed Rulemaking A. Regulatory History and Information The... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Desert Storm Shootout; Lake Havasu, Lake... establishing a temporary safety zone on the navigable waters of the Colorado River in Lake Havasu, Lake...

  17. The DREAM complex promotes gene body H2A.Z for target repression.

    PubMed

    Latorre, Isabel; Chesney, Michael A; Garrigues, Jacob M; Stempor, Przemyslaw; Appert, Alex; Francesconi, Mirko; Strome, Susan; Ahringer, Julie

    2015-03-01

    The DREAM (DP, Retinoblastoma [Rb]-like, E2F, and MuvB) complex controls cellular quiescence by repressing cell cycle genes, but its mechanism of action is poorly understood. Here we show that Caenorhabditis elegans DREAM targets have an unusual pattern of high gene body HTZ-1/H2A.Z. In mutants of lin-35, the sole p130/Rb-like gene in C. elegans, DREAM targets have reduced gene body HTZ-1/H2A.Z and increased expression. Consistent with a repressive role for gene body H2A.Z, many DREAM targets are up-regulated in htz-1/H2A.Z mutants. Our results indicate that the DREAM complex facilitates high gene body HTZ-1/H2A.Z, which plays a role in target gene repression. PMID:25737279

  18. Microstructure and rolling capability of modified AZ31-Ce-Gd alloys

    SciTech Connect

    Li Wenping; Zhou Hong; Lin Pengyu; Zhao Shizhe

    2009-11-15

    AZ31-Ce-Gd alloys were studied and the influence of cerium (Ce) and gadolinium (Gd) on the microstructure and rolling capability of AZ31 alloy was investigated. The results indicated that the grains of AZ31 alloy were refined with Ce and Gd addition. Ce and Gd addition resulted in the formation of Al{sub 4}Ce, Al{sub 2}Gd and Mg{sub 3}Gd. After homogenization and rolling, the Al{sub 4}Ce, Al{sub 2}Gd and Mg{sub 3}Gd still existed. The rolling capability of AZ31 alloy was improved obviously with Ce and Gd addition. However, once Gd content increased to a certain value, the rolling capability of the modified alloy declined but still better than that of AZ31 alloy.

  19. 78 FR 71493 - Special Local Regulation; Lake Havasu City Christmas Boat Parade of Lights; Colorado River; Lake...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-29

    ... Acronyms BNM Broadcast Notices to Mariners COTP Captain of the Port DHS Department of Homeland Security FR... Boat Parade of Lights; Colorado River; Lake Havasu, AZ AGENCY: Coast Guard, DHS. ACTION: Temporary... in support of the Lake Havasu City Christmas Boat Parade of Lights on the Colorado River....

  20. The histone variant H2A.Z is an important regulator of enhancer activity

    PubMed Central

    Brunelle, Mylène; Nordell Markovits, Alexei; Rodrigue, Sébastien; Lupien, Mathieu; Jacques, Pierre-Étienne; Gévry, Nicolas

    2015-01-01

    Gene regulatory programs in different cell types are largely defined through cell-specific enhancers activity. The histone variant H2A.Z has been shown to play important roles in transcription mainly by controlling proximal promoters, but its effect on enhancer functions remains unclear. Here, we demonstrate by genome-wide approaches that H2A.Z is present at a subset of active enhancers bound by the estrogen receptor alpha (ERα). We also determine that H2A.Z does not influence the local nucleosome positioning around ERα enhancers using ChIP sequencing at nucleosomal resolution and unsupervised pattern discovery. We further highlight that H2A.Z-enriched enhancers are associated with chromatin accessibility, H3K122ac enrichment and hypomethylated DNA. Moreover, upon estrogen stimulation, the enhancers occupied by H2A.Z produce enhancer RNAs (eRNAs), and recruit RNA polymerase II as well as RAD21, a member of the cohesin complex involved in chromatin interactions between enhancers and promoters. Importantly, their recruitment and eRNAs production are abolished by H2A.Z depletion, thereby revealing a novel functional link between H2A.Z occupancy and enhancer activity. Taken together, our findings suggest that H2A.Z acts as an important player for enhancer functions by establishing and maintaining a chromatin environment required for RNA polymerase II recruitment, eRNAs transcription and enhancer-promoters interactions, all essential attributes of enhancer activity. PMID:26319018

  1. Microstructure and Elevated Temperature Properties of Die-cast AZ91- xNd Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Wang, Limin; An, Jian; Liu, Yongbing

    2008-10-01

    The effect of Nd addition on the microstructure and mechanical properties of a die-cast AZ91 alloy was investigated in the present work. The results show that the die-cast AZ91 alloy is composed of ?-Mg matrix and ?-Mg17Al12 phase. Nd addition into the AZ91 alloy leads to the formation of rare earth containing intermetallic phase. Al4Nd phase forms when Nd content is less than or equal to 1.0 wt.%. Al2Nd phase appears simultaneously when Nd content reaches to 3.0 wt.%. The size and volume fraction of ?-Mg17Al12 phase decrease, because of the newly formed Al-Nd phase. And the ?-Mg17Al12 phase distributes from reticular to dispersive. Nd addition has a little effect on the room temperature properties of the die-cast AZ91 alloy, but greatly improves the elevated temperature properties. The tensile strength of AZ91-0.5Nd and AZ91-1.0Nd alloy tested at 150 C is even close to the room temperature strength. The AZ91-1.0Nd alloy has the optimal properties.

  2. The histone variant H2A.Z is an important regulator of enhancer activity.

    PubMed

    Brunelle, Mylne; Nordell Markovits, Alexei; Rodrigue, Sbastien; Lupien, Mathieu; Jacques, Pierre-tienne; Gvry, Nicolas

    2015-11-16

    Gene regulatory programs in different cell types are largely defined through cell-specific enhancers activity. The histone variant H2A.Z has been shown to play important roles in transcription mainly by controlling proximal promoters, but its effect on enhancer functions remains unclear. Here, we demonstrate by genome-wide approaches that H2A.Z is present at a subset of active enhancers bound by the estrogen receptor alpha (ER?). We also determine that H2A.Z does not influence the local nucleosome positioning around ER? enhancers using ChIP sequencing at nucleosomal resolution and unsupervised pattern discovery. We further highlight that H2A.Z-enriched enhancers are associated with chromatin accessibility, H3K122ac enrichment and hypomethylated DNA. Moreover, upon estrogen stimulation, the enhancers occupied by H2A.Z produce enhancer RNAs (eRNAs), and recruit RNA polymerase II as well as RAD21, a member of the cohesin complex involved in chromatin interactions between enhancers and promoters. Importantly, their recruitment and eRNAs production are abolished by H2A.Z depletion, thereby revealing a novel functional link between H2A.Z occupancy and enhancer activity. Taken together, our findings suggest that H2A.Z acts as an important player for enhancer functions by establishing and maintaining a chromatin environment required for RNA polymerase II recruitment, eRNAs transcription and enhancer-promoters interactions, all essential attributes of enhancer activity. PMID:26319018

  3. Effect of Annealing on Microstructure and Tensile Properties of 5052/AZ31/5052 Clad Sheets

    NASA Astrophysics Data System (ADS)

    Nie, Huihui; Liang, Wei; Chi, Chengzhong; Li, Xianrong; Fan, Haiwei; Yang, Fuqian

    2015-12-01

    Three-layered 5052Al/AZ31Mg/5052Al (5052/AZ31/5052) clad sheets were fabricated by four-pass rolling and annealed under different conditions. Under the optimal annealing condition, homogeneous and equiaxial grains with an average AZ31 grain size of 5.24 m were obtained and the maximum values of ultimate tensile strength and elongation of the clad sheet reached 230 MPa and 18%, respectively. Electron backscatter diffraction analysis showed that the AZ31 layer had a typical rolling texture with its c-axis parallel to the normal direction. The fraction of low-angle grain boundaries in the 5052 layer was nearly four times more than that in the AZ31 layer because of different deformation extent and recrystallization driving forces. The textures of Al3Mg2 and Mg17Al12 were similar to that of 5052 because of the deformation coordination during the rolling and recrystallization process. The orientation relationship between Mg17Al12 and AZ31 seemed to be (110) Mg17Al12//(10-11) AZ31.

  4. Conformal AZ5214-E resist deposition on patterned (1 0 0) InP substrates

    NASA Astrophysics Data System (ADS)

    Elis, P.; Gregusov, D.; Martaus, J.; Kostic, I.

    2006-02-01

    A draping technique was studied to deposit thin, visco-elastic AZ5214-E resist layers from a water surface over planar and patterned substrates. A visco-elastic AZ5214-E layer forms on the water surface when a drop of AZ5214-E makes contact with it. The drop spreads out within a fraction of a second because of a large positive difference in surface tension between water and AZ5214-E. The spreading mechanism lies in the ability of PGMEA (AZ5214-E liquid constituent) to form hydrogen bonds with water. We brought AZ5214-E drops to make contact with water at 20 0.1 C via adhesive forces to form AZ5214-E layers on the water surface of (1) circular and (2) square shapes. In case (1), the layers, formed from drops of V = 3 l, had thickness t ap c sdot 4V/??-2 for ? < 32 mm, and t > c sdot 4V/??-2 for larger ?. In case (2), the layers had t ap a + bV for V between 7 and 12 l on square-shaped water surfaces of constant area A = 34.5 mm 34.5 mm. All layers exhibited microscopic waviness with an average thickness uniformity u ~ 91%, and submicron waviness with a root-mean-square roughness ? ~ 12 nm and a lateral correlation length ? ~ 32 m. AZ5214-E sheets coated conformally high mesa objects with sharp convex and concave edges: 61 m high ridges confined to ~35-inclined facets and 9 m high ridges confined to negatively sloped facets. The draping technique can be used to deposit conformal AZ5214-E layers over non-planar substrates for non-planar device processing.

  5. Mineral Mapping Using AVIRIS Data at Ray Mine, AZ

    NASA Technical Reports Server (NTRS)

    McCubbin, Ian; Lang, Harold; Green, Robert O.; Roberts, Dar

    1998-01-01

    Imaging Spectroscopy enables the identification and mapping of surface mineralogy over large areas. This study focused on assessing the utility of Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data for environmental impact analysis over the Environmental Protection Agency's (EPA) high priority Superfund site Ray Mine, AZ. Using the Spectral Angle Mapper (SAM) algorithm to analyze AVIRIS data makes it possible to map surface materials that are indicative of acid generating minerals. The improved performance of the AVIRIS sensor since 1996 provides data with sufficient signal to noise ratio to characterize up to 8 image endmembers. Specifically we employed SAM to map minerals associated with mine generated acid waste, namely jarositc, goethite, and hematite, in the presence of a complex mineralogical background.

  6. An 18-Inch Direct Drive Alt-Az Telescope

    NASA Astrophysics Data System (ADS)

    Genet, Russell M.; Rowe, Dave; Gray, Dan; Albertson, Billy; Chiu, Wilson; Kirkup, Michelle; Murphy, Drew; Ridgely, John; Schmitt, Josh; Swanson, Matt; Urban, Rob; Liu, Tong; Branch, Howard; Chelborad, Cary; Keller, Allan

    2008-05-01

    A modest aperture alt-az telescope has been designed and is being built for student use at California Polytechnic State University. The telescope's drive system has no gears, belts, or friction wheels; instead direct drive motors and high resolution encoders are completely integrated into the bearing assemblies and telescope superstructure. In altitude, for instance, a ring of permanent magnets is firmly mounted to the OTA while an opposing ring of coils is mounted on the inside of a fork arm. The electronic control system has been designed to operate these brushless motors in a high- precision mode. To achieve the highest possible closed loop servo bandwidth, the structure was designed -- using finite element analysis as well as traditional tools -- to have a very high natural frequency. The direct drive system and stiff structure should effectively counter wind gusts when the telescope is operated out in the open or within a roll-off roof observatory.

  7. Fabrication and characterization of AZ91/CNT magnesium matrix composites

    NASA Astrophysics Data System (ADS)

    Park, Yong-Ha; Park, Yong-Ho; Park, Ik-Min; Oak, Jeong-jung; Kimura, Hisamichi; Cho, Kyung-Mox

    2008-12-01

    Carbon Nano Tube (CNT) reinforced AZ91 metal matrix composites (MMC) were fabricated by the squeeze infiltrated method. Properties of magnesium alloys have been improved by impurity reduction, surface treatment and alloy design, and thus the usage for the magnesium alloys has been extended recently. However there still remain barriers for the adaption of magnesium alloys for engineering materials. In this study, we report light-weight, high strength heat resistant magnesium matrix composites. Microstructural study and tensile test were performed for the squeeze infiltrated magnesium matrix composites. The wear properties were characterized and the possibility for the application to automotive power train and engine parts was investigated. It was found that the squeeze infiltration technique is a proper method to fabricate magnesium matrix composites reducing casting defects such as pores and matrix/reinforcement interface separation etc. Improved tensile and mechanical properties were obtained with CNT reinforcing magnesium alloys

  8. -dimensional Symmetry Catalysts for A-Z Gas Loading Fusion

    NASA Astrophysics Data System (ADS)

    Chubb, Talbot

    2011-03-01

    An epitaxial mating of a metal layer to a chemically stable ionic crystal minimizes system energy for cold fusion based on Bloch function symmetry and using gas loading and nm-Pd at a favored interface. To achieve epitaxy second and third metal layers need to have imperfections. One thinks of the stable ionic crystal as a template and the nano-Pd solid as a malleable lattice. The interior volume of the nano-Pd solid has a face-centered cubic structure. ZrO2 was the template ionic crystal used in A-Z gas loading studies at elevated T in (2005). A template crystal using the sapphire crystal equivalent of a double-layer graphene crystal is suggested. Impurity Rh and Ru are suggested as impurity atoms in the nano-metal (as in gem-quality Zircon) and a amall amount of interstitial H in addition to dominant D as involved in diffusion. Ref.

  9. Microstructural stability after severe plastic deformation of AZ31 Magnesium

    NASA Astrophysics Data System (ADS)

    Young, J. P.; Askari, H.; Hovanski, Y.; Heiden, M. J.; Field, D. P.

    2014-08-01

    Friction stir processing (FSP) and equal channel angular pressing (ECAP) were used to modify the microstructure of twin roll cast (TRC) AZ31 magnesium. The influence of these processes on the microstructural properties of the material was investigated. It was found that both processes produced microstructures with an average grain size of less than 10 pm, suggesting that they have the potential for superplastic deformation. Heat treatments were performed on the TRC, ECAP and FSP materials to assess their microstructural stability. Both the ECAP and TRC material were found to be fairly stable, showing normal grain growth while the FSP material grew substantially at temperatures above 200C. The activation energy of grain boundary motion of the TRC material was calculated to be 167 kJ/mol.

  10. Project W-211 Initial Tank Retrieval Systems (ITRS) Description of Operations for 241-AZ-102

    SciTech Connect

    BRIGGS, S.R.

    2000-02-25

    The primary purpose of the Initial Tank Retrieval Systems (ITRS) is to provide systems for retrieval of radioactive wastes stored in underground double-shell tanks (DSTs) for transfer to alternate storage, evaporation, pretreatment or treatment, while concurrently reducing risks associated with safety watch list and other DSTs. This Description of Operation (DOO) defines the control philosophy for the waste retrieval system for Tank 241-AZ-102 (AZ-102). This DOO provides a basis for the detailed design of the Project W-211 Retrieval Control System (RCS) for AZ-102 and also establishes test criteria for the RCS.

  11. Influence of Aluminum Content on Grain Refinement and Strength of AZ31 Magnesium GTA Weld Metal

    SciTech Connect

    Babu, N. Kishore; Cross, Carl E.

    2012-06-28

    The goal is to characterize the effect of Al content on AZ31 weld metal, the grain size and strength, and examine role of Al on grain refinement. The approach is to systematically vary the aluminum content of AZ31 weld metal, Measure average grain size in weld metal, and Measure cross-weld tensile properties and hardness. Conclusions are that: (1) increased Al content in AZ31 weld metal results in grain refinement Reason: higher undercooling during solidification; (2) weld metal grain refinement resulted in increased strength & hardness Reason: grain boundary strengthening; and (3) weld metal strength can be raised to wrought base metal levels.

  12. Corrosion resistance of titanium ion implanted AZ91 magnesium alloy

    SciTech Connect

    Liu Chenglong; Xin Yunchang; Tian Xiubo; Zhao, J.; Chu, Paul K.

    2007-03-15

    Degradable metal alloys constitute a new class of materials for load-bearing biomedical implants. Owing to their good mechanical properties and biocompatibility, magnesium alloys are promising in degradable prosthetic implants. The objective of this study is to improve the corrosion behavior of surgical AZ91 magnesium alloy by titanium ion implantation. The surface characteristics of the ion implanted layer in the magnesium alloys are examined. The authors' results disclose that an intermixed layer is produced and the surface oxidized films are mainly composed of titanium oxide with a lesser amount of magnesium oxide. X-ray photoelectron spectroscopy reveals that the oxide has three layers. The outer layer which is 10 nm thick is mainly composed of MgO and TiO{sub 2} with some Mg(OH){sub 2}. The middle layer that is 50 nm thick comprises predominantly TiO{sub 2} and MgO with minor contributions from MgAl{sub 2}O{sub 4} and TiO. The third layer from the surface is rich in metallic Mg, Ti, Al, and Ti{sub 3}Al. The effects of Ti ion implantation on the corrosion resistance and electrochemical behavior of the magnesium alloys are investigated in simulated body fluids at 37{+-}1 deg. C using electrochemical impedance spectroscopy and open circuit potential techniques. Compared to the unimplanted AZ91 alloy, titanium ion implantation significantly shifts the open circuit potential (OCP) to a more positive potential and improves the corrosion resistance at OCP. This phenomenon can be ascribed to the more compact surface oxide film, enhanced reoxidation on the implanted surface, as well as the increased {beta}-Mg{sub 12}Al{sub 17} phase.

  13. Vatican City.

    PubMed

    1984-11-01

    Vatican City, the administrative and spiritual capital of the Roman catholic Church, has a population of 1000. Citizenship is generally accorded only to those who reside in Vatican City for reasons of office of employment. Supreme legislative, executive, and judicial power is currentily exercised by Pope John Paul II, the 1st non-italian pope in 5 centuries. The State of Vatican City is recognized by many nations as an independent sovereign state under the temporal jurisdiction of the Pope. By 1984, 108 countries had established diplomatic relations with the Holy See, most of which are not Roman Catholic. Third World countries comprise a large proportion of countries that have recently established relations with the Holy See. The US re-established relations with the Vatican in 1984 and there is frequent contact and consultation between the 2 states on key international issues. PMID:12178097

  14. City 2020+

    NASA Astrophysics Data System (ADS)

    Schneider, C.; Buttstädt, M.; Merbitz, H.; Sachsen, T.; Ketzler, G.; Michael, S.; Klemme, M.; Dott, W.; Selle, K.; Hofmeister, H.

    2010-09-01

    This research initiative CITY 2020+ assesses the risks and opportunities for residents in urban built environments under projected demographic and climate change for the year 2020 and beyond, using the City of Aachen as a case study. CITY 2020+ develops scenarios, options and tools for planning and developing sustainable future city structures. We investigate how urban environment, political structure and residential behavior can best be adapted, with attention to the interactions among structural, political, and sociological configurations and with their consequences on human health. Demographers project that in the EU-25-States by 2050, approximately 30% of the population will be over age 65. Also by 2050, average tem¬peratures are projected to rise by 1 to 2 K. Combined, Europe can expect enhanced thermal stress and higher levels of particulate matter. CITY 2020+ amongst other sub-projects includes research project dealing with (1) a micro-scale assessment of blockages to low-level cold-air drainage flow into the city centre by vegetation and building structures, (2) a detailed analysis of the change of probability density functions related to the occurrence of heat waves during summer and the spatial and temporal structure of the urban heat island (UHI) (3) a meso-scale analysis of particulate matter (PM) concentrations depending on topography, local meteorological conditions and synoptic-scale weather patterns. First results will be presented specifically from sub-projects related to vegetation barriers within cold air drainage, the assessment of the UHI and the temporal and spatial pattern of PM loadings in the city centre. The analysis of the cold air drainage flow is investigated in two consecutive years with a clearing of vegetation stands in the beginning of the second year early in 2010. The spatial pattern of the UHI and its possible enhancement by climate change is addressed employing a unique setup using GPS devices and temperature probes fixed to several public transport units running all across the city. This is accompanied by an analysis of probability density functions (PDF) for heat waves based on recent climate data and climate projections. A dense net of 40 PM measurement sites is operated in order to obtain the spatial pattern of PM concentration as depending on meteorological condition and location. It is lined out how this climate related sub-projects interact with investigations on social networks, governance issues, buildings structure development and health outcome. Related to the later the chemical composition of PM is analyzed in more detail and related to the spatial patterns of health deficiencies. At a later stage City2020+ will propose new strategies based on cooperation from the fields of medicine, geography, sociology, history, civil engineering, and architecture for adapting the city for future needs. The Project CITY 2020+ is part of the interdisciplinary Project House HumTec (Human Sciences and Technology) at RWTH Aachen University funded by the Excellence Initiative of the German federal and state governments through the Deutsche Forschungsgemeinschaft (German Research Foundation, DFG).

  15. The Histone Chaperones FACT and Spt6 Restrict H2A.Z from Intragenic Locations.

    PubMed

    Jeronimo, Clia; Watanabe, Shinya; Kaplan, Craig D; Peterson, Craig L; Robert, Franois

    2015-06-18

    H2A.Z is a highly conserved histone variant involved in several key nuclear processes. It is incorporated into promoters by SWR-C-related chromatin remodeling complexes, but whether it is also actively excluded from non-promoter regions is not clear. Here we provide genomic and biochemical evidence that the RNA polymerase II (RNA Pol II) elongation-associated histone chaperones FACT and Spt6 both contribute to restricting H2A.Z from intragenic regions. In the absence of FACT or Spt6, the lack of efficient nucleosome reassembly coupled to pervasive incorporation of H2A.Z by mislocalized SWR-C alters chromatin composition and contributes to cryptic initiation. Therefore, chaperone-mediated H2A.Z confinement is crucial for restricting the chromatin signature of gene promoters that otherwise may license or promote cryptic transcription. PMID:25959393

  16. a Manganese Oxide Contained Coating for Biodegradable AZ31B Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Yan, Tingting; Tan, Lili; Xiong, Dangsheng; Zhang, Bingchun; Yang, Ke

    A manganese oxide contained coating was prepared on biodegradable AZ31B magnesium alloy to control the degradation of AZ31B and improve its biocompatibility. Morphology, composition, and corrosion resistance of the coating were studied. The SEM observations showed that the coating was approximately 4-6 ?m in thickness with net-like microcracks. The XPS analysis indicated that the coating was mainly composed of MgO, Mg(OH)2, MnO2, Mn2O3, and Mn3O4. It was found that AZ31B with such coating showed better corrosion resistance in simulated blood plasma through electrochemical and immersion tests. The hemolytic assay indicated that the treated AZ31B had no hemolytic effect.

  17. 75 FR 49526 - Freescale Semiconductor, Inc., Technical Information Center, Tempe, AZ; Freescale Semiconductor...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-13

    ... Register on November 17, 2009 (74 FR 59249). At the request of the petitioners, the Department reviewed the... Employment and Training Administration Freescale Semiconductor, Inc., Technical Information Center, Tempe, AZ; Freescale Semiconductor, Inc., Technical Information Center, Woburn, MA; Amended Certification...

  18. Draft Genome Sequence of Lysobacter capsici AZ78, a Bacterium Antagonistic to Plant-Pathogenic Oomycetes.

    PubMed

    Puopolo, Gerardo; Sonego, Paolo; Engelen, Kristof; Pertot, Ilaria

    2014-01-01

    Lysobacter capsici AZ78, isolated from tobacco rhizosphere, effectively controls Phytophthora infestans and Plasmopara viticola on tomato and grapevine plants, respectively. We report the first draft genome sequence of the L. capsici species. PMID:24762937

  19. 77 FR 20356 - Foreign-Trade Zone 277-Western Maricopa County, AZ; Application for Manufacturing Authority...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-04

    ... Manufacturing Authority; Suntech Arizona, Inc., (Solar Panel Manufacturing), Goodyear, AZ An application has..., Inc., grantee of FTZ 277, requesting manufacturing authority on behalf of Suntech Arizona, Inc... foreign inputs that become scrap or waste during manufacturing. FTZ designation would further...

  20. Operational Test Report for the 241-AZ-101 Ultrasonic Interface Level Analyzer

    SciTech Connect

    ANDREWS, J.E.

    2000-03-28

    This document comprises the Operational Test Report for the 241-AZ-101 Ultrasonic Interface Level Analyzer. The objective of the testing was to verify that all equipment and components functioned as designed following construction completion and turnover to operations.

  1. 75 FR 28778 - Magma Flood Retarding Structure (FRS) Supplemental Watershed Plan, Pinal County, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-24

    ... Natural Resources Conservation Service Magma Flood Retarding Structure (FRS) Supplemental Watershed Plan, Pinal County, AZ AGENCY: Natural Resources Conservation Service. ACTION: Notice of a Finding of No...; the Council on Environmental Quality Regulations (40 CFR part 1500); and the Natural...

  2. Draft Genome Sequence of Lysobacter capsici AZ78, a Bacterium Antagonistic to Plant-Pathogenic Oomycetes

    PubMed Central

    Sonego, Paolo; Engelen, Kristof; Pertot, Ilaria

    2014-01-01

    Lysobacter capsici AZ78, isolated from tobacco rhizosphere, effectively controls Phytophthora infestans and Plasmopara viticola on tomato and grapevine plants, respectively. We report the first draft genome sequence of the L. capsici species. PMID:24762937

  3. Microstructure and corrosion resistance of Ce-V conversion coating on AZ31 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Jiang, Xiao; Guo, Ruiguang; Jiang, Shuqin

    2015-06-01

    A Ce-V conversion coating was developed to improve the corrosion resistance of AZ31 magnesium alloy. Scanning electronic microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrometer (XPS), grazing incidence X-ray diffraction (GIXRD) and the ball cratering test were adopted to study the morphology, chemical composition, structure and thickness of the coating. The coating has duplex structure with network and its thickness is about 2 ?m. The coating contains high contents of Ce and V, which exhibits amorphous structure. Potentiodynamic polarization shows the coating can increase the corrosion potential and reduce the corrosion current density of AZ31 magnesium alloy. Moreover, the electrochemical impedance spectra exhibit the coating significantly improves the corrosion resistance of AZ31 magnesium alloy. Results indicate that the Ce-V conversion coating can provide effective protection to AZ31 magnesium alloy.

  4. Air composition over Siberian cities.

    NASA Astrophysics Data System (ADS)

    Belan, B. D.; Ivlev, G. A.; Kozlov, A. S.; Marinaite, I. I.; Peneko, V. V.; Simonenkov, D. V.; Fofonov, A. V.; Khodzher, T. V.; Arshinov, M. Yu.

    2009-04-01

    It is typical feature of Siberian cities that the quality of the atmosphere significantly depends on the climate conditions. During more than half of year, stable atmospheric stratification dominates over Siberia with temperature inversions, favoring accumulation of pollutants of different origin in the lower atmospheric layers. In addition to severe climatic conditions, modern industrial cities experience increasingly intensifying effect of anthropogenic factors on the environment and human health. Urban conditions give rise to distinct mesoclimates favoring accumulation of pollutants. In this case, natural and anthropogenic systems (power-generating and industrial objects, traffic, etc.) interact very closely. In this paper we present experimental results of the study the local air circulation effect on air composition of industrial cities of Siberian region. In our studies we have used AKV-2 mobile station, designed at the Institute of Atmospheric Optics SB RAS. The instrumentation of the station provides measurements of air temperature and humidity, wind speed and direction, total solar radiation; aerosol number density in two size ranges (0.4-10 microns by use of a modernized AZ-6 optical particle counter, and from 3 to 200 nm with a diffusion spectrometer of aerosols), and concentration of trace gases (NO, NO2, O3, SO2, CO, CO2). In addition to the continuous observations during the station motion, in Angarsk, Usol'e-Sibirskoe, Tulun, Nizhneudinsk, Taishet, Kansk, Krasnoyarsk, and Achinsk, we have carried measurements during stops at the city entry, near center, and at the exit. These observations were aimed to estimate the contribution of urban circulation to impurity accumulation on the city territory and to the change of thermodynamic regime. Such a contribution was found in all of the above-mentioned cities. Maximum of NO concentration is observed at crossroads of the main highways and decreases away from them. It should be noted that the NO distribution almost the same as the distribution of CO, which is also of "automobile engine" origin. In the center of cities where usually impurities are accumulated, concentration of SO2, NO2, CO, and aerosol number density as well are several times higher than in the city periphery. On the contrary, the ozone content in center is much lower. In most of the cases, the urban samples have 2-3 times more chemical elements than the background samples. The total concentrations of PAHs in aerosol matter of the cities varied from 20 to 30 ng/m3. PAH concentrations, as well as the percentage relation between them are determined by the place of aerosol sampling, i.e., by locations of pollution sources. Among the identified PAHs in the public green space and industrial zones of Angarsk, the predominating species are phenanthrene, pyrene, and fluoranthene, whose total amount reaches 80% of the mass of the detected PAHs. In summer, owing to more effective atmospheric ventilation, the effects of local circulation substantially weaken. As a result, a significant pollutant accumulation in the central parts of the cities may not always be detected.

  5. Final results of double-shell tank 241-AZ-101 ultrasonic inspection

    SciTech Connect

    JENSEN, C.E.

    1999-08-23

    This document presents the results and documentation of the nondestructive ultrasonic examination of tank 241-AZ-101. A tank inspection supplier was retained to provide and use an ultrasonic examination system (equipment, procedures, and inspectors) to scan a limited area of double-shell tank 241-AZ-101 primary tank wall and welds. The inspection found one reportable indication of thinning and no reportable pitting, corrosion, or cracking.

  6. Effect of microstructure on the zinc phosphate conversion coatings on magnesium alloy AZ91

    NASA Astrophysics Data System (ADS)

    Van Phuong, Nguyen; Moon, Sungmo; Chang, Doyon; Lee, Kyu Hwan

    2013-01-01

    The effect of the microstructure, particularly of ?-Mg17Al12 phase, on the formation and growth of zinc phosphate conversion coatings on magnesium alloy AZ91 (AZ91) was studied. The zinc phosphate coatings were formed on AZ91 with different microstructures produced by heat treatment. The effect of the microstructure on the zinc phosphate coatings were examined using optical microscope (OM), X-ray diffraction (XRD), coatings weight and etching weight balances, scanning electron microscopy (SEM) and salt immersion test. Results showed that as-cast AZ91 contained a high volume fraction of the ?-Mg17Al12 phase and it was dissolved into ?-Mg phase during heat treatment at 400 C. The ?-phase became center for hydrogen evolution during phosphating reaction (cathodic sites). The decreased volume fraction of the ?-phase caused decreasing both coatings weight and etching weight of the phosphating process. However, it increased the crystal size of the coatings and improved corrosion resistance of AZ91 by immersing in 0.5 M NaCl solution. Results also showed that the structure of the zinc phosphate conversion on AZ91 consisted of two layers: an outer crystal Zn3(PO4)24H2O (hopeite) and an inner which was mainly composed of MgZn2(PO4)2 and Mg3(PO4)2. A mechanism for the formation of two layers of the coatings was also proposed in this study.

  7. Effect of Ca and Rare Earth Elements on Impression Creep Properties of AZ91 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Nami, B.; Razavi, H.; Mirdamadi, S.; Shabestari, S. G.; Miresmaeili, S. M.

    2010-08-01

    Creep properties of AZ91 magnesium alloy and AZRC91 (AZ91 + 1 wt pct RE + 1.2 wt pct Ca) alloy were investigated using the impression creep method. It was shown that the creep properties of AZ91 alloy are significantly improved by adding Ca and rare earth (RE) elements. The improvement in creep resistance is mainly attributed to the reduction in the amount and continuity of eutectic ?(Mg17Al12) phase as well as the formation of new Al11RE3 and Al2Ca intermetallic compounds at interdendritic regions. It was found that the stress exponent of minimum creep rate, n, varies between 5.69 and 6 for AZ91 alloy and varies between 5.81 and 6.46 for AZRC91 alloy. Activation energies of 120.9 8.9 kJ/mol and 100.6 7.1 kJ/mol were obtained for AZ91 and AZRC91 alloys, respectively. It was shown that the lattice and pipe-diffusion-controlled dislocation climb are the dominant creep mechanisms for AZ91 and AZRC91 alloys, respectively. The constitutive equations, correlating the minimum creep rate with temperature and stress, were also developed for both alloys.

  8. Lysobacter capsici AZ78 can be combined with copper to effectively control Plasmopara viticola on grapevine.

    PubMed

    Puopolo, Gerardo; Giovannini, Oscar; Pertot, Ilaria

    2014-01-01

    The bacterial genus Lysobacter represents a still underdeveloped source of biocontrol agents able to protect plants against pathogenic oomycetes. In this work the L. capsici strain AZ78 was evaluated with regard to the biological control of Plasmopara viticola, the causal agent of grapevine downy mildew. L. capsici AZ78 is able to resist copper ions and its resistance to this metal is probably due to the presence of genes coding for copper oxidase (copA) and copper exporting PIB-type ATPases (ctpA). The presence of both genes was also detected in other members of the Lysobacter genus. Resistance to copper allowed L. capsici AZ78 to be combined with a low-dose of a copper-based fungicide, leading to more effective control of grapevine downy mildew. Notably, prophylactic application of L. capsici AZ78 alone to grapevine leaves reduced downy mildew disease to the same degree as a copper-based fungicide. Furthermore, L. capsici AZ78 persists in the phyllosphere of grapevine plants and tolerates environmental stresses such as starvation, freezing, mild heat shock and UV light irradiation. These traits suggest that L. capsici AZ78 could be a suitable candidate for developing a new biofungicide to be used in combination with copper to control grapevine downy mildew. PMID:24140153

  9. Removal of H2A.Z by INO80 promotes homologous recombination

    PubMed Central

    Alatwi, Hanan E; Downs, Jessica A

    2015-01-01

    The mammalian INO80 remodelling complex facilitates homologous recombination (HR), but the mechanism by which it does this is unclear. Budding yeast INO80 can remove H2A.Z/H2B dimers from chromatin and replace them with H2A/H2B dimers. H2A.Z is actively incorporated at sites of damage in mammalian cells, raising the possibility that H2A.Z may need to be subsequently removed for resolution of repair. Here, we show that H2A.Z in human cells is indeed rapidly removed from chromatin flanking DNA damage by INO80. We also report that the histone chaperone ANP32E, which is implicated in removing H2AZ from chromatin, similarly promotes HR and appears to work on the same pathway as INO80 in these assays. Importantly, we demonstrate that the HR defect in cells depleted of INO80 or ANP32E can be rescued by H2A.Z co-depletion, suggesting that H2A.Z removal from chromatin is the primary function of INO80 and ANP32E in promoting homologous recombination. PMID:26142279

  10. Hydrogen City

    NASA Astrophysics Data System (ADS)

    Lodhi, M. A. K.

    Sources of energy from which hydrogen can be produced in massive quantity and at low cost are surveyed briefly. A short account of devices to be employed for the production of hydrogen are presented. Primarily the sun, sea and runoff waters are to be harnessed. The methodology and devices to be used to convert the available but diffused energy into hydrogen are helio-hydro-gravity, helio-aero-gravity, salt gradient solar pond, principle of magnetohydrodynamics, etc. The discussion on the inexhaustibility of naturally occurring sources utilized and/or harnessed in this process will lead to the low cost for hydrogen production. This process is imagined to be designed in a model city named 'Hydrogen City' which produces hydrogen and is run on hydrogen in order to meet its energy needs.

  11. Oxide Film and Porosity Defects in Magnesium Alloy AZ91

    SciTech Connect

    Wang, Liang; Rhee, Hongjoo; Felicelli, Sergio D.; Sabau, Adrian S; Berry, John T.

    2009-01-01

    Porosity is a major concern in the production of light metal parts. This work aims to identify some of the mechanisms of microporosity formation in magnesium alloy AZ91. Microstructure analysis was performed on several samples obtained from gravity-poured ingots in graphite plate molds. Temperature data during cooling was acquired with type K thermocouples at 60 Hz at three locations of each casting. The microstructure of samples extracted from the regions of measured temperature was then characterized with optical metallography. Tensile tests and conventional four point bend tests were also conducted on specimens cut from the cast plates. Scanning electron microscopy was then used to observe the microstructure on the fracture surface of the specimens. The results of this study revealed the existence of abundant oxide film defects, similar to those observed in aluminum alloys. Remnants of oxide films were detected on some pore surfaces, and folded oxides were observed in fracture surfaces indicating the presence of double oxides entrained during pouring.

  12. Fine particulate chemical composition and light extinction at Meadview, AZ

    SciTech Connect

    Delbert J. Eatough; Wenxuan Cui; Jeffery Hull; Robert J. Farber

    2006-12-15

    The concentration of fine particulate nitrate, sulfate, and carbonaceous material was measured for 12-hr daynight samples using diffusion denuder samplers during the Project Measurement of Haze and Visibility Effects (MOHAVE) July to August 1992 Summer Intensive study at Meadview, AZ, just west of Grand Canyon National Park. Organic material was measured by several techniques. Only the diffusion denuder method measured the semivolatile organic material. Fine particulate sulfate and nitrate (using denuder technology) determined by various groups agreed. Based on the various collocated measurements obtained during the Project MOHAVE study, the precision of the major fine particulate species was {+-} 0.6 {mu}g/m{sup 3} organic material, {+-} 0.3 {mu}g/m{sup 3} ammonium sulfate, and {+-} 0.07 {mu}g/m{sup 3} ammonium nitrate. Fine particulate organic material was the principal particulate contributor to light extinction during the study period, with fine particulate sulfate as the second most important contributor. Particle light extinction was dominated by sulfate and organic material during periods of lowest light extinction. Combination of the extinction data and chemical mass balance analysis of sulfur oxides sources in the region indicate that the major anthropogenic contributors to light extinction were from the Los Angeles, CA, and Las Vegas, NV, urban areas. Mohave Power Project associated secondary sulfate was a negligible contributor to light extinction. 49 refs., 12 figs., 7 tabs.

  13. A study on the relationships between corrosion properties and chemistry of thermally oxidised surface films formed on polished commercial magnesium alloys AZ31 and AZ61

    NASA Astrophysics Data System (ADS)

    Feliu, Sebastián; Samaniego, Alejandro; Barranco, Violeta; El-Hadad, A. A.; Llorente, Irene; Serra, Carmen; Galván, J. C.

    2014-03-01

    This paper studies the changes in chemical composition of the thin oxide surface films induced by heating in air at 200 °C for time intervals from 5 min to 60 min on the freshly polished commercial AZ31 and AZ61 alloys with a view to better understanding their protective properties. This thermal treatment resulted in the formation of layers enriched in metallic aluminium at the interface between the outer MgO surface films and the bulk material. A strong link was found between the degree of metallic Al enrichment in the subsurface layer (from 10 to 15 at.%) observed by XPS (X-ray photoelectron spectroscopy) in the AZ61 treated samples and the increase in protective properties observed by EIS (electrochemical impedance spectroscopy) in the immersion test in 0.6 M NaCl. Heating for 5-60 min in air at 200 °C seems to be an effective, easy to perform and inexpensive method for increasing the corrosion resistance of the AZ61 alloy by approximately two or three times.

  14. Dynamic behavior and constitutive modeling of magnesium alloys AZ91D and AZ31B under high strain rate compressive loading

    NASA Astrophysics Data System (ADS)

    Xiao, Jing; Ahmad, Iram Raza; Shu, D. W.

    2014-03-01

    The dynamic stress-strain characteristics of magnesium alloys have not been sufficiently studied experimentally. Thus, the present work investigated compressive dynamic stress-strain characteristics of two representative magnesium alloys: AZ91D and AZ31B at high strain rates and elevated temperatures. In order to use the stress-strain characteristics in numerical simulations to predict the impact response of components, the stress-strain characteristics must be modeled. The most common approach is to use accepted constitutive laws. The results from the experimental study of the response of magnesium alloys AZ91D and AZ31B under dynamic compressive loading, at different strain rates and elevated temperatures are presented here. Johnson-Cook model was used to best fit the experimental data. The material parameters required by the model were obtained and the resultant stress-strain curves of the two alloys for each testing condition were plotted. It is found that the dynamic stress-strain relationship of both magnesium alloys are strain rate and temperature dependent and can be described reasonably well at high strain rates and room temperature by Johnson-Cook model except at very low strains. This might be due to the fact that the strain rate is not strictly constant in the early stage of deformation.

  15. Electrochemical characterization and in-vitro bio-assessment of AZ31B and AZ91E alloys as biodegradable implant materials.

    PubMed

    Ur Rahman, Zia; Pompa, Luis; Haider, Waseem

    2015-08-01

    The degradation of magnesium alloys, AZ31B and AZ91E, are under review due to a their ability to degrade under physiological conditions and successively yield an oxidized biocompatible by-product which can safely be absorbed by the body. By exploiting the biodegradability of magnesium alloys, the prospects of developing an unprecedented class of implant are at hand. To do so however, the rate of corrosion of the alloys must be modified in order to better suit physiological conditions. Therefore, anodization was carried out on AZ31B and AZ91E specimens to alter the surface chemistry to reduce the corrosion rates and improve biocompatibility. Scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and contact angle meter, were used to characterize and compare the surfaces of untreated and anodized magnesium alloys. Corrosion behavior was evaluated by electrochemical tests using potentiodynamic polarization and electrochemical impedance spectroscopy, to verify changes in corrosion rates as a result of anodization. Finally, a bio-assessment using MTS assays and fluorescent microscopy were carried out to ensure that the anodization process had no compromise on the biocompatibility of the magnesium alloys. The study indicated that the anodization process did alter the surface chemistry of the alloys, yielding slower corrosion rates, while causing no adverse effects in regards to biocompatibility. PMID:26216551

  16. Superplastic Formability of AZ31 Magnesium Alloy Sheets Produced by Twin Roll Casting and Sequential Hot Rolling

    NASA Astrophysics Data System (ADS)

    Yu, Yandong; Lin, Kai; Jiang, Peng

    2013-07-01

    In this paper, superplastic tensile testing and gas bulging forming of AZ31 and AZ31 + Y + Sr magnesium alloys produced by twin roll casting (TRC) and sequential hot rolling were carried out. At 673 K, the superplastic formability of the TRC AZ31 magnesium alloy sheets added Y and Sr elements has improved significantly compared to the common TRC AZ31 sheets. Formations of cavities on the bulging part go through three stages of the nucleation, growth and aggregation, finally cavities merging lead to rupture at the top of the bulging part.

  17. Characterizing the optical performance of AZ93 with a fluoropolymer overcoat under ultraviolet exposure

    NASA Astrophysics Data System (ADS)

    Huang, Alvin Y.; Schmidl, William D.; Soares, Carlos E.

    2008-08-01

    AZ93 with a fluoropolymer overcoat is an option to simplify ground handling of space hardware. The overcoat applied on some on-orbit International Space Station (ISS) hardware provides contamination protection for optically sensitive ceramic thermal control coatings. However, if the fluoropolymer is not eroded on-orbit by atomic oxygen (AO), then it will darken. This will increase the solar absorptance resulting in possible thermal performance degradation. If the fluoropolymer overcoat was not present, optical performance would be significantly improved. To characterize the optical performance of the AZ93 with the fluoropolymer overcoat for modeling the UV degradation, laboratory testing of the coating was performed at Marshall Space Flight Center (MSFC). Sample coupons prepared by AZ Technology were exposed under vacuum to ultraviolet radiation. At periodic intervals, the samples were removed from the testing chamber to acquire images and to measure the solar absorptance. The images showed visible differences between AZ93 with the overcoat and without the overcoat as vacuum ultraviolet (VUV) exposure increased. Darkening is more pronounced in the samples with the fluoropolymer overcoat. This was also evident in the solar absorptance measurements. Optical properties of AZ93 with the fluoropolymer overcoat significantly degraded in comparison to those without the overcoat. A short period of little change followed by an exponential rise in solar absorptance was observed. The optical degradation of the fluoropolymer overcoat is described in terms of surface reaction chemistry and kinetics and is found to follow a pseudo first order reaction rate.

  18. Arabidopsis meiotic crossover hot spots overlap with H2A.Z nucleosomes at gene promoters.

    PubMed

    Choi, Kyuha; Zhao, Xiaohui; Kelly, Krystyna A; Venn, Oliver; Higgins, James D; Yelina, Nataliya E; Hardcastle, Thomas J; Ziolkowski, Piotr A; Copenhaver, Gregory P; Franklin, F Chris H; McVean, Gil; Henderson, Ian R

    2013-11-01

    PRDM9 directs human meiotic crossover hot spots to intergenic sequence motifs, whereas budding yeast hot spots overlap regions of low nucleosome density (LND) in gene promoters. To investigate hot spots in plants, which lack PRDM9, we used coalescent analysis of genetic variation in Arabidopsis thaliana. Crossovers increased toward gene promoters and terminators, and hot spots were associated with active chromatin modifications, including H2A.Z, histone H3 Lys4 trimethylation (H3K4me3), LND and low DNA methylation. Hot spot-enriched A-rich and CTT-repeat DNA motifs occurred upstream and downstream, respectively, of transcriptional start sites. Crossovers were asymmetric around promoters and were most frequent over CTT-repeat motifs and H2A.Z nucleosomes. Pollen typing, segregation and cytogenetic analysis showed decreased numbers of crossovers in the arp6 H2A.Z deposition mutant at multiple scales. During meiosis, H2A.Z forms overlapping chromosomal foci with the DMC1 and RAD51 recombinases. As arp6 reduced the number of DMC1 or RAD51 foci, H2A.Z may promote the formation or processing of meiotic DNA double-strand breaks. We propose that gene chromatin ancestrally designates hot spots within eukaryotes and PRDM9 is a derived state within vertebrates. PMID:24056716

  19. NO{sub x} sensitivity of Phoenix, AZ ozone

    SciTech Connect

    Hyde, P.; Oliver, W.R.; Tran, K.; Heisler, S.L.

    1998-12-31

    Of critical concern in the Urban Airshed Model (UAM) simulations of Phoenix, AZ ozone was the issue of NO{sub x} sensitivity. With the base case inventory of the Voluntary Early Ozone Plan, which had a mass VOC/NO{sub x} ratio in the inventory of 1.06, the airshed had a decided NO{sub x} disbenefit. To determine whether this NO{sub x} disbenefit would prevail with different emissions inventories, alternative inventories were constructed within the limits of the estimated uncertainties for each combination of major source category and pollutant combination. These alternative inventories had mass VOC/NO{sub x} ratios both lower and higher than the base case inventory. Paired UAM simulations of each inventory with 10% NO{sub x} reductions were performed for each alternative. In varying the mass VOC/NO{sub x} inventory ratio from 0.6 to 2.1, the NO{sub x} disbenefit prevailed with ratios of up to 1.7, while at higher ratios, the NO{sub x} benefit prevailed. For the Reanalysis of the Voluntary Early Ozone Plan, a revised base-case inventory was constructed. This inventory differed substantially from its predecessor in VOC and NO{sub x} tonnages in the onroad and offroad mobile source categories and for biogenic emissions, but the overall VOC/NO{sub x} tonnages were similar to the earlier inventory. This inventory also showed a NO{sub x} disbenefit. Two series of extensive emission sensitivity tests showed that the NO{sub x} disbenefit prevailed with all inventories that could be considered plausible.

  20. Impression Creep Behavior of a Cast AZ91 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Kabirian, F.; Mahmudi, R.

    2009-01-01

    The creep behavior of the cast AZ91 magnesium alloy was investigated by impression testing. The tests were carried out under constant punching stress in the range 100 to 650 MPa, corresponding to 0.007 ? ? imp/ G ? 0.044, at temperatures in the range 425 to 570 K. Assuming a power-law relationship between the impression velocity and stress, depending on the testing temperature, stress exponents of 4.2 to 6.0 were obtained. When the experimental creep rates were normalized to the grain size and effective diffusion coefficient, a stress exponent of approximately 5 was obtained, which is in complete agreement with stress exponents determined by the conventional creep testing of the same material reported in the literature. Calculation of the activation energy showed a slight decrease in the activation energy with increasing stress such that the creep-activation energy of 122.9 kJ/mol at ? imp/ G = 0.020 decreases to 94.0 kJ/mol at ? imp/ G = 0.040. Based on the obtained stress exponents and activation energy data, it is proposed that dislocation climb is the controlling creep mechanism. However, due to the decreasing trend of creep-activation energy with stress, it is suggested that two parallel mechanisms of lattice and pipe-diffusion-controlled dislocation climb are competing. To elucidate the contribution of each mechanism to the overall creep deformation, the creep rates were calculated based on the effective activation energy. This yielded a criterion that showed that, in the high-stress regimes, the experimental activation energies fall in the range in which the operative creep mechanism is dislocation climb controlled by dislocation pipe diffusion. In the low-stress regime, however, the lattice-diffusion dislocation climb is dominant.

  1. Devolatilization or melting of carbonates at Meteor Crater, AZ?

    NASA Astrophysics Data System (ADS)

    Hrz, F.; Archer, P. D.; Niles, P. B.; Zolensky, M. E.; Evans, M.

    2015-06-01

    We have investigated the carbonates in the impact melts and in a monolithic clast of highly shocked Coconino sandstone of Meteor Crater, AZ to evaluate whether melting or devolatilization is the dominant response of carbonates during high-speed meteorite impact. Both melt- and clast-carbonates are calcites that have identical crystal habits and that contain anomalously high SiO2 and Al2O3. Also, both calcite occurrences lack any meteoritic contamination, such as Fe or Ni, which is otherwise abundantly observed in all other impact melts and their crystallization products at Meteor Crater. The carbon and oxygen isotope systematics for both calcite deposits suggest a low temperature environment (<100 C) for their precipitation from an aqueous solution, consistent with caliche. We furthermore subjected bulk melt beads to thermogravimetric analysis and monitored the evolving volatiles with a quadrupole mass spectrometer. CO2 yields were <5 wt%, with typical values in the 2 wt% range; also total CO2 loss is positively correlated with H2O loss, an indication that most of these volatiles derive from the secondary calcite. Also, transparent glasses, considered the most pristine impact melts, yield 100 wt% element totals by EMPA, suggesting complete loss of CO2. The target dolomite decomposed into MgO, CaO, and CO2; the CO2 escaped and the CaO and MgO combined with SiO2 from coexisting quartz and FeO from the impactor to produce the dominant impact melt at Meteor Crater. Although confined to Meteor Crater, these findings are in stark contrast to Osinski et al. (2008) who proposed that melting of carbonates, rather than devolatilization, is the dominant process during hypervelocity impact into carbonate-bearing targets, including Meteor Crater.

  2. Fine particulate chemical composition and light extinction at Meadview, AZ.

    PubMed

    Eatough, Delbert J; Cui, Wenxuan; Hull, Jeffery; Farber, Robert J

    2006-12-01

    The concentration of fine particulate nitrate, sulfate, and carbonaceous material was measured for 12-hr day-night samples using diffusion denuder samplers during the Project Measurement of Haze and Visibility Effects (MOHAVE) July to August 1992 Summer Intensive study at Meadview, AZ, just west of Grand Canyon National Park. Organic material was measured by several techniques. Only the diffusion denuder method measured the semivolatile organic material. Fine particulate sulfate and nitrate (using denuder technology) determined by various groups agreed. Based on the various collocated measurements obtained during the Project MOHAVE study, the precision of the major fine particulate species was +/- 0.6 microg/m3 organic material, +/- 0.3 microg/m3 ammonium sulfate, and +/- 0.07 microg/m3 ammonium nitrate. Data were also available on fine particulate crustal material, fine and coarse particulate mass from the Interagency Monitoring of Protected Visual Environments sampling system, and relative humidity (RH), light absorption, particle scattering, and light extinction measurements from Project MOHAVE. An extinction budget was obtained using mass scattering coefficients estimated from particle size distribution data. Literature data were used to estimate the change in the mass scattering coefficients for the measured species as a function of RH and for the absorption of light by elemental carbon. Fine particulate organic material was the principal particulate contributor to light extinction during the study period, with fine particulate sulfate as the second most important contributor. During periods of highest light extinction, contributions from fine particulate organic material, sulfate, and light-absorbing carbon dominated the extinction of light by particles. Particle light extinction was dominated by sulfate and organic material during periods of lowest light extinction. Combination of the extinction data and chemical mass balance analysis of sulfur oxides sources in the region indicate that the major anthropogenic contributors to light extinction were from the Los Angeles, CA, and Las Vegas, NV, urban areas. Mohave Power Project associated secondary sulfate was a negligible contributor to light extinction. PMID:17195488

  3. Learning Cities as Healthy Green Cities: Building Sustainable Opportunity Cities

    ERIC Educational Resources Information Center

    Kearns, Peter

    2012-01-01

    This paper discusses a new generation of learning cities we have called EcCoWell cities (Economy, Community, Well-being). The paper was prepared for the PASCAL International Exchanges (PIE) and is based on international experiences with PIE and developments in some cities. The paper argues for more holistic and integrated development so that

  4. Ultrasonic Spot Welding of AZ31B to Galvanized Mild Steel

    SciTech Connect

    Pan, Dr. Tsung-Yu; Franklin, Teresa; Pan, Professor Jwo; Brown, Elliot; Santella, Michael L

    2010-01-01

    Ultrasonic spot welds were made between sheets of 0.8-mm-thick hot-dip-galvanized mild steel and 1.6-mm-thick AZ31B-H24. Lap-shear strengths of 3.0-4.2 kN were achieved with weld times of 0.3-1.2 s. Failure to achieve strong bonding of joints where the Zn coating was removed from the steel surface indicate that Zn is essential to the bonding mechanism. Microstructure characterization and microchemical analysis indicated temperatures at the AZ31-steel interfaces reached at least 344 C in less than 0.3 s. The elevated temperature conditions promoted annealing of the AZ31-H24 metal and chemical reactions between it and the Zn coating.

  5. Effects of process parameters on microstructural evolution and properties of AZ61 alloy during hot extrusion

    NASA Astrophysics Data System (ADS)

    Lu, Y. L.; Li, X. C.; Xu, W. T.; Wu, D.; Yang, M.

    2015-12-01

    Extrusion testing of AZ61 alloys were conducted at deformation temperatures of 300°C to 410°C and extrusion ratios of 3, 10 and 16 respectively to optimize the process parameters. The experimental results show that deformation process parameters significantly affect microstructures and properties. Optical microscope observation shows that grains are refined greatly during hot extrusion and the mechanical properties are improved with increasing the extrusion ratio. For AZ61 alloy, the optimal extrusion temperature is 370 °C. When deformation temperature increases, more slip systems participate in the plastic deformation, which leads to the decrease of the cleavage surface. After severe plastic deformation, a remarkable improvement of ductility of AZ61 alloy has been found. The ductile fracture mechanism is gradually dominant instead of brittle fracture with increasing the extrusion ratio.

  6. Tank 241-AZ-101 Mixer Pump Test Vapor Sampling and Analysis Plan

    SciTech Connect

    TEMPLETON, A.M.

    2000-01-31

    This sampling and analysis plan (SAP) identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements for vapor samples obtained during the operation of mixer pumps in tank 241-AZ-101. The primary purpose of the mixer pump test (MPT) is to demonstrate that the two 300 horsepower mixer pumps installed in tank 241-AZ-101 can mobilize the settled sludge so that it can be retrieved for treatment and vitrification Sampling will be performed in accordance with Tank 241-AZ-101 Mixer Pump Test Data Quality Objective (Banning 1999) and Data Quality Objectives for Regulatory Requirements for Hazardous and Radioactive Air Emissions Sampling and Analysis (Mulkey 1999). The sampling will verify if current air emission estimates used in the permit application are correct and provide information for future air permit applications.

  7. Tank 241-AZ-101 Mixer Pump Test Vapor Sampling and Analysis Plan

    SciTech Connect

    TEMPLETON, A.M.

    2000-04-10

    This sampling and analysis plan (SAP) identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements for vapor samples obtained during the operation of mixer pumps in tank 241-AZ-101. The primary purpose of the mixer pump test (MPT) is to demonstrate that the two 300 horsepower mixer pumps installed in tank 241-AZ-101 can mobilize the settled sludge so that it can be retrieved for treatment and vitrification. Sampling will be performed in accordance with Tank 241-AZ-101 Mixer Pump Test Data Quality Objective (Banning 1999) and Data Quality Objectives for Regulatory Requirements for Hazardous and Radioactive Air Emissions Sampling and Analysis (Mulkey 1999). The sampling will verify if current air emission estimates used in the permit application are correct and provide information for future air permit applications.

  8. Tank 241-AZ-101 Mixer Pump Test Vapor Sampling and Analysis Plan

    SciTech Connect

    TEMPLETON, A.M.

    2000-03-06

    This sampling and analysis plan (SAP) identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements for vapor samples obtained during the operation of mixer pumps in tank 241-AZ-101. The primary purpose of the mixer pump test (MPT) is to demonstrate that the two 300 horsepower mixer pumps installed in tank 241-AZ-101 can mobilize the settled sludge so that it can be retrieved for treatment and vitrification. Sampling will be performed in accordance with Tank 241-AZ-101 Mixer Pump Test Data Quality Objective (Banning 1999) and Data Quality Objectives for Regulatory Requirements for Hazardous and Radioactive Air Emissions Sampling and Analysis (Mulkey 1999). The sampling will verify if current air emission estimates used in the permit application are correct and provide information for future air permit applications.

  9. Formation of intermetallic compound coating on magnesium AZ91 cast alloy

    NASA Astrophysics Data System (ADS)

    Zhu, Tianping; Gao, Wei

    2009-08-01

    This study describes an intermetallic compound coating formed on AZ91 Mg cast alloy. The Al sputtered on AZ91 cast alloy reacted with substrate during a short period of heat treatment at 435C, resulting in the formation of a continuous intermetallic compound layer. The short period treatment has the advantage of minimizing the negative effect on the microstructure of substrate and the mechanical properties, comparing with the reported diffusion coatings. DSC measurement and examination on the cross-section of Al sputtered samples show that local melting occurred along the Al/substrate interface at the temperature range between 430~435C. The formation mechanism of intermetallic compound coating is proposed in terms of the local melting at Al/substrate interface. The salt water immersion test showed significant improvement in corrosion resistance of the intermetallic compound coated AZ91 cast alloy compared with the as-cast alloys.

  10. Dynamic recrystallization and microstructure evolution of AZ31 magnesium alloy produced by extrusion through rotating container

    NASA Astrophysics Data System (ADS)

    Li, Feng; Bian, Nan; Xu, Yongchao; Zeng, Xiang

    2016-01-01

    In order to research the dynamic recrystallization (DRX) and grain refinement mechanisms in the process of extrusion through the rotating container, hot compression experiment of AZ31 magnesium alloy was carried out. Through the combination of experimental data and Yada empirical model, the DRX model of AZ31 magnesium alloy was established. Based on this DRX model, the numerical simulation of AZ31 magnesium alloy extrusion through the rotating container process was performed. The research results indicated, with the same process parameters of conventional extrusion, the shear stress increased significantly at the same position during the process of extrusion through the rotating container. This stress change promoted the occurrence of DRX and the increased recrystallization volume fraction. The average grain size obviously decreased. The equiaxed grains increased and the distribution uniformity was improved. These characteristics provided a theoretical basis for a better understanding of the enhanced comprehensive mechanical properties during the extrusion through the rotating container.

  11. Electrodeposition of high corrosion resistance Cu/Ni-P coating on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Shan; Cao, Fahe; Chang, Linrong; Zheng, JunJun; Zhang, Zhao; Zhang, Jianqing; Cao, Chunan

    2011-08-01

    High corrosion resistance Cu/Ni-P coatings were electrodeposited on AZ91D magnesium alloy via suitable pretreatments, such as one-step acid pickling-activation, once zinc immersion and environment-friendly electroplated copper as the protective under-layer, which made Ni-P deposit on AZ91D Mg alloy in acid plating baths successfully. The pH value and current density for Ni-P electrodeposition were optimized to obtain high corrosion resistance. With increasing the phosphorous content of the Ni-P coatings, the deposits were found to gradually transform to amorphous structure and the corrosion resistance increased synchronously. The anticorrosion ability of AZ91D Mg alloy was greatly improved by the amorphous Ni-P deposits, which was investigated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The corrosion current density ( Icorr) of the coated Mg alloy substrate is about two orders of magnitude less than that of the uncoated.

  12. The Effect of Texture on the Corrosion Behavior of AZ31 Mg Alloy

    NASA Astrophysics Data System (ADS)

    Song, Guang-Ling

    2012-06-01

    Magnesium (Mg) grains show anisotropic corrosion behavior, which implies that the single-phase, hot-rolled Mg alloy AZ31 sheet, if highly textured, will have different corrosion performance depending on its crystallographic orientation of the grains. Its rolling surface, dominated by (0001) basal crystallographic planes, is more corrosion resistant than its cross-section surface, which is mainly composed of \\{ 10overline{1} 0\\} and \\{ 11overline{2} 0\\} prismatic crystallographic planes. Furthermore, grain refinement by hot rolling is beneficial to the overall corrosion resistance of AZ31 because of the dissolution of AlMn(Fe) intermetallic precipitates in the alloy. Surface compressive deformation machining can lead to refined grains and an expected preferred grain orientation, thus improving the corrosion resistance of AZ31 alloy.

  13. Tank 241-AZ-102 Privatization Push Mode Core Sampling and Analysis Plan

    SciTech Connect

    TEMPLETON, A.M.

    1999-07-08

    This sampling and analysis plan (SAP) identifies characterization objectives pertaining to sample collection, laboratory analytical evaluation, and reporting requirements for samples obtained from tank 241-AZ-102. The purpose of this sampling event is to obtain information about the characteristics of the contents of 241-AZ-102. Push mode core samples will be obtained from risers 15C and 24A to provide sufficient material for the chemical analyses and tests required to satisfy these data quality objectives. The 222-S Laboratory will extrude core samples, composite the liquids and solids, perform chemical analyses, and provide subsamples to the Process Chemistry Laboratory. The Process Chemistry Laboratory will prepare test plans and perform process tests to evaluate the behavior of the 241-AZ-102 waste undergoing the retrieval and treatment scenarios defined in the applicable DQOs. Requirements for analyses of samples originating in the process tests will be documented in the corresponding test plan.

  14. H2A.Z.1 mono-ubiquitylation antagonizes BRD2 to maintain poised chromatin in ESCs

    PubMed Central

    Surface, Lauren E.; Fields, Paul A.; Subramanian, Vidya; Behmer, Russell; Udeshi, Namrata; Peach, Sally E.; Jaffe, Jacob D.; Boyer, Laurie A.

    2016-01-01

    SUMMARY Histone variant H2A.Z occupies the promoters of active and poised, bivalent genes in ESCs to regulate developmental programs, yet how it contributes to these contrasting states is poorly understood. Here, we investigate the function of H2A.Z.1 mono-ubiquitylation (H2A.Z.1ub) by mutation of the PRC1 target residues (H2A.Z.1K3R3). We show that H2A.Z.1K3R3 is properly incorporated at target promoters in murine ESCs (mESCs), however, loss of mono-ubiquitylation leads to de-repression of bivalent genes, loss of Polycomb binding, and to faulty lineage commitment. Using quantitative proteomics, we find that tandem bromodomain proteins, including the BET family member Brd2, are enriched in H2A.Z.1 chromatin. We further show that Brd2 is gained at de-repressed promoters in H2A.Z.1K3R3 mESCs whereas Brd2 inhibition restores gene silencing at these sites. Together, our study reveals an antagonistic relationship between H2A.Z.1ub and Brd2 to regulate the transcriptional balance at bivalent genes to enable proper execution of developmental programs. PMID:26804911

  15. Draft Genome Sequence of the Sulfolobales Archaeon AZ1, Obtained through Metagenomic Analysis of a Mexican Hot Spring

    PubMed Central

    Martínez-Romero, Esperanza

    2014-01-01

    The Sulfolobales archaea have been found inhabiting acidic hot springs all over the world. Here, we report the 1.798-Mbp draft genome sequence of the thermoacidophilic Sulfolobales archaeon AZ1, reconstructed from the metagenome of a Mexican hot spring. Sequence-based comparisons revealed that the Sulfolobales archaeon AZ1 represents a novel candidate genus. PMID:24604657

  16. 75 FR 61660 - Proposed Modification of Class D and E Airspace, and Revocation of Class E Airspace; Flagstaff, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-06

    ... Proposed Modification of Class D and E Airspace, and Revocation of Class E Airspace; Flagstaff, AZ AGENCY... action proposes to modify Class D and E airspace at Flagstaff, AZ, to accommodate aircraft departing and... Class E airspace designated as an extension to a Class D or E surface area at Flagstaff Pulliam...

  17. VizieR Online Data Catalog: AzTEC/ASTE 1.1mm survey of SSA22 (Umehata+, 2014)

    NASA Astrophysics Data System (ADS)

    Umehata, H.; Tamura, Y.; Kohno, K.; Hatsukade, B.; Scott, K. S.; Kubo, M.; Yamada, T.; Ivison, R. J.; Cybulski, R.; Aretxaga, I.; Austermann, J.; Hughes, D. H.; Ezawa, H.; Hayashino, T.; Ikarashi, S.; Iono, D.; Kawabe, R.; Matsuda, Y.; Matsuo, H.; Nakanishi, K.; Oshima, T.; Perera, T.; Takata, T.; Wilson, G. W.; Yun, M. S.

    2015-01-01

    We used the AzTEC camera operating at 1.1mm mounted on the ASTE 10-m submillimetre telescope located at Pampa la Bola, near Cerro Chajnantor in northern Chile. All of the AzTEC/ASTE observations of SSA22 were carried out at night during 2007 August-September and 2008 August-September. (4 data files).

  18. 14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION... TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ Pt. 93, Subpt. U, App. Appendix to Subpart U of Part 93Special Flight Rules in the Vicinity of the Grand Canyon National Park,...

  19. 14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION... TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ Pt. 93, Subpt. U, App. Appendix to Subpart U of Part 93Special Flight Rules in the Vicinity of the Grand Canyon National Park,...

  20. 14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION... TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ Pt. 93, Subpt. U, App. Appendix to Subpart U of Part 93Special Flight Rules in the Vicinity of the Grand Canyon National Park,...

  1. 14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION... TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ Pt. 93, Subpt. U, App. Appendix to Subpart U of Part 93Special Flight Rules in the Vicinity of the Grand Canyon National Park,...

  2. Blocking spinal CCR2 with AZ889 reversed hyperalgesia in a model of neuropathic pain

    PubMed Central

    2010-01-01

    Background The CCR2/CCL2 system has been identified as a regulator in the pathogenesis of neuropathy-induced pain. However, CCR2 target validation in analgesia and the mechanism underlying antinociception produced by CCR2 antagonists remains poorly understood. In this study, in vitro and in vivo pharmacological approaches using a novel CCR2 antagonist, AZ889, strengthened the hypothesis of a CCR2 contribution to neuropathic pain and provided confidence over the possibilities to treat neuropathic pain with CCR2 antagonists. Results We provided evidence that dorsal root ganglia (DRG) cells harvested from CCI animals responded to stimulation by CCL2 with a concentration-dependent calcium rise involving PLC-dependent internal stores. This response was associated with an increase in evoked neuronal action potentials suggesting these cells were sensitive to CCR2 signalling. Importantly, treatment with AZ889 abolished CCL2-evoked excitation confirming that this activity is CCR2-mediated. Neuronal and non-neuronal cells in the spinal cord were also excited by CCL2 applications indicating an important role of spinal CCR2 in neuropathic pain. We next showed that in vivo spinal intrathecal injection of AZ889 produced dose-dependent analgesia in CCI rats. Additionally, application of AZ889 to the exposed spinal cord inhibited evoked neuronal activity and confirmed that CCR2-mediated analgesia involved predominantly the spinal cord. Furthermore, AZ889 abolished NMDA-dependent wind-up of spinal withdrawal reflex pathway in neuropathic animals giving insight into the spinal mechanism underlying the analgesic properties of AZ889. Conclusions Overall, this study strengthens the important role of CCR2 in neuropathic pain and highlights feasibility that interfering on this mechanism at the spinal level with a selective antagonist can provide new analgesia opportunities. PMID:21143971

  3. Corrosion and mechanical performance of AZ91 exposed to simulated inflammatory conditions.

    PubMed

    Brooks, Emily K; Der, Stephanie; Ehrensberger, Mark T

    2016-03-01

    Magnesium (Mg) and its alloys, including Mg-9%Al-1%Zn (AZ91), are biodegradable metals with potential use as temporary orthopedic implants. Invasive orthopedic procedures can provoke an inflammatory response that produces hydrogen peroxide (H2O2) and an acidic environment near the implant. This study assessed the influence of inflammation on both the corrosion and mechanical properties of AZ91. The AZ91 samples in the inflammatory protocol were immersed for three days in a complex biologically relevant electrolyte (AMEM culture media) that contained serum proteins (FBS), 150mM of H2O2, and was titrated to a pH of 5. The control protocol immersed AZ91 samples in the same biologically relevant electrolyte (AMEM & FBS) but without H2O2 and the acid titration. After 3days all samples were switched into fresh AMEM & FBS for an additional 3-day immersion. During the initial immersion, inflammatory protocol samples showed increased corrosion rate determined by mass loss testing, increased Mg and Al ion released to solution, and a completely corroded surface morphology as compared to the control protocol. Although corrosion in both protocols slowed once the test electrolyte solution was replaced at 3days, the samples originally exposed to the simulated inflammatory conditions continued to display enhanced corrosion rates as compared to the control protocol. These lingering effects may indicate the initial inflammatory corrosion processes modified components of the surface oxide and corrosion film or initiated aggressive localized processes that subsequently left the interface more vulnerable to continued enhanced corrosion. The electrochemical properties of the interfaces were also evaluated by EIS, which found that the corrosion characteristics of the AZ91 samples were potentially influenced by the role of intermediate adsorption layer processes. The increased corrosion observed for the inflammatory protocol did not affect the flexural mechanical properties of the AZ91 at any time point assessed. PMID:26706549

  4. H2A.Z nucleosome positioning has no impact on genetic variation in Drosophila genome.

    PubMed

    Tang, Yitao; Dong, Shan; Cao, Xinkai; Zhou, Qing; Ding, Guitao; Jiang, Cizhong

    2013-01-01

    Nucleosome occupancy results in complex sequence variation rate heterogeneity by either increasing mutation rate or inhibiting DNA repair in yeast, fish, and human. H2A.Z nucleosome is extensively involved in gene transcription activation and regulation. To test whether H2A.Z nucleosome has the similar impact on sequence variability in the Drosophila genome, we profiled the H2A.Z nucleosome occupancy and sequence variation rate at gene ends and splicing sites. Consistent with previous studies, H2A.Z nucleosome positioning helps to demarcate the borders of exons. Nucleosome occupancy is anticorrelated with sequence divergence rate in the regions flanking transcription start sites and splicing sites. However, there is no rate heterogeneity between the linker DNA and H2A.Z nucleosomal DNA regardless of nucleosome occupancy, fuzziness, positioning in promoter, coding, and intergenic regions, young or old genes. But the rate at intergenic nucleosomes and the flanking linker regions is higher than that at the genic counterparts. Further analyses found that the high sequence divergence rate in the promoter regions that are usually nucleosome depleted regions may be likely resulted from the high mutation rate in the enriched tandem repeats. Interestingly, within nucleosomes spanning splicing sites, sequence variability of nucleosomal DNA significantly increases from the end within exons to the other end protruding into introns. The relaxed functional constraint in introns contributes to the high rate of nucleosomal DNA residing in introns while the strict functional constraint in exons maintains the low rate of nucleosomal DNA residing in exons. Taken together, H2A.Z nucleosome occupancy has no effect on sequence variability of Drosophila genome, which is likely determined by local sequence composition and the concomitant selection pressure. PMID:23472174

  5. Genetic complementation analysis showed distinct contributions of the N-terminal tail of H2A.Z to epigenetic regulations.

    PubMed

    Kusakabe, Masayuki; Oku, Hiroyuki; Matsuda, Ryo; Hori, Tetsuya; Muto, Akihiko; Igarashi, Kazuhiko; Fukagawa, Tatsuo; Harata, Masahiko

    2016-02-01

    H2A.Z is one of the most evolutionally conserved histone variants. In vertebrates, this histone variant has two isoforms, H2A.Z.1 and H2A.Z.2, each of which is coded by an individual gene. H2A.Z is involved in multiple epigenetic regulations, and in humans, it also has relevance to carcinogenesis. In this study, we used the H2A.Z DKO cells, in which both H2A.Z isoform genes could be inducibly knocked out, for the functional analysis of H2A.Z by a genetic complementation assay, as the first example of its kind in vertebrates. Ectopically expressed wild-type H2A.Z and two N-terminal mutants, a nonacetylable H2A.Z mutant and a chimera in which the N-terminal tail of H2A.Z.1 was replaced with that of the canonical H2A, complemented the mitotic defects of H2A.Z DKO cells similarly, suggesting that both acetylation and distinctive sequence of the N-terminal tail of H2A.Z are not required for mitotic progression. In contrast, each one of these three forms of H2A.Z complemented the transcriptional defects of H2A.Z DKO cells differently. These results suggest that the N-terminal tail of vertebrate H2A.Z makes distinctively different contributions to these epigenetic events. Our results also imply that this genetic complementation system is a novel and useful tool for the functional analysis of H2A.Z. PMID:26833946

  6. 75 FR 11580 - Florida Power Corporation, City of Alachua, City of Bushnell, City of Gainesville, City of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-11

    ... Corporation, City of Alachua, City of Bushnell, City of Gainesville, City of Kissimmee, City of Leesburg, City of New Smyrna Beach and Utilities Commission, City of New Smyrna Beach, City of Ocala, Orlando Utilities Commission and City of Orlando, Seminole Electric Cooperative, Inc., Crystal River Unit 3...

  7. Anticorrosive magnesium hydroxide coating on AZ31 magnesium alloy by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Zhu, Yanying; Wu, Guangming; Zhao, Qing; Zhang, Yun-Hong; Xing, Guangjian; Li, Donglin

    2009-09-01

    Magnesium alloys are potential biodegradable biomaterials in orthopedic surgery. However, the rapid degradation rate has limited their application in biomedical field. A great deal of studies have been done to improve the resistance of magnesium alloys. In this article, An anticorrosive magnesium hydroxide coating with a thickness of approximately 100?m was formed on an AZ31 magnesium alloy by hydrothermal method. The morphology of the coatings were observed by an optical microscope and SEM. And the samples were soaked in hank's solution (37C) to investigate the corrosion resistance. Magnesium alloy AZ31 with magnesium hydroxide coatings present superior corrosion resistance than untreated samples.

  8. Mechanism of the formation of stannate and cerium conversion coatings on AZ91D magnesium alloys

    NASA Astrophysics Data System (ADS)

    Lee, Y. L.; Chu, Y. R.; Chen, F. J.; Lin, C. S.

    2013-07-01

    The characteristics of the formation of conversion coatings on an AZ91D Mg alloy were detailed. Because the galvanic effect prevailed around the eutectic ? + ?, alkaline stannate conversion coatings nucleated first near the ? phase where plenty Mg2+ were present. Conversely, the formation of cerium conversion coatings largely relied on an increase in the interfacial pH. Intense dissolution of the primary ? phase in acid cerium nitrate solution caused hydrogen bubble evolution, which, in turn, resulted in blisters. It is evident that the galvanic corrosion routes on the AZ91D depend on the pH of the conversion coating solution.

  9. Effects of the types of overlap on the mechanical properties of FSSW welded AZ series magnesium alloy joints

    NASA Astrophysics Data System (ADS)

    Wang, Dan; Shen, Jun; Wang, Lin-Zhi

    2012-03-01

    The effects of the types of overlap on the mechanical properties of the friction stir spot welding (FSSW) welded AZ series magnesium alloy joints were investigated by microstructural observations, microhardness tests, and tensile tests. The results show that the microstructure of the stir zone adjacent to the periphery of the rotating pin is mainly composed of the upper sheet. The average distance D between the longitudinal segment of the curved interface and the keyhole periphery, the tensile shear force, and the microhardness of the stir zone of the FSSW welded AZ61 alloy joint are the highest in all samples. During FSSW of AZ31 and AZ61 dissimilar magnesium alloys, the irregular deformation of the longitudinal segment of the curved interface appears, while the microhardness of the stir zone is higher when AZ61 alloy is the upper sheet. Moreover, the microhardness of the stir zone increases initially and then decreases sharply in the longitudinal test position.

  10. Clean Cities Fact Sheet

    SciTech Connect

    Not Available

    2004-01-01

    This fact sheet explains the Clean Cities Program and provides contact information for all coalitions and regional offices. It answers key questions such as: What is the Clean Cities Program? What are alternative fuels? How does the Clean Cities Program work? What sort of assistance does Clean Cities offer? What has Clean Cities accomplished? What is Clean Cities International? and Where can I find more information?

  11. CESIUM REMOVAL FROM TANKS 241-AN-103 & 241-SX-105 & 241-AZ-101 & 241AZ-102 COMPOSITE FOR TESTING IN BENCH SCALE STEAM REFORMER

    SciTech Connect

    DUNCAN JB; HUBER HJ

    2011-04-21

    This report documents the preparation of three actual Hanford tank waste samples for shipment to the Savannah River National Laboratory (SRNL). Two of the samples were dissolved saltcakes from tank 241-AN-103 (hereafter AN-103) and tank 241-SX-105 (hereafter SX-105); one sample was a supernate composite from tanks 241-AZ-101 and 241-AZ-102 (hereafter AZ-101/102). The preparation of the samples was executed following the test plans LAB-PLAN-10-00006, Test Plan for the Preparation of Samples from Hanford Tanks 241-SX-105, 241-AN-103, 241-AN-107, and LAB-PLN-l0-00014, Test Plan for the Preparation of a Composite Sample from Hanford Tanks 241-AZ-101 and 241-AZ-102 for Steam Reformer Testing at the Savannah River National Laboratory. All procedural steps were recorded in laboratory notebook HNF-N-274 3. Sample breakdown diagrams for AN-103 and SX-105 are presented in Appendix A. The tank samples were prepared in support of a series of treatability studies of the Fluidized Bed Steam Reforming (FBSR) process using a Bench-Scale Reformer (BSR) at SRNL. Tests with simulants have shown that the FBSR mineralized waste form is comparable to low-activity waste glass with respect to environmental durability (WSRC-STI-2008-00268, Mineralization of Radioactive Wastes by Fluidized Bed Steam Reforming (FBSR): Comparisons to Vitreous Waste Forms and Pertinent Durability Testing). However, a rigorous assessment requires long-term performance data from FBSR product formed from actual Hanford tank waste. Washington River Protection Solutions, LLC (WRPS) has initiated a Waste Form Qualification Program (WP-5.2.1-2010-001, Fluidized Bed Steam Reformer Low-level Waste Form Qualification) to gather the data required to demonstrate that an adequate FBSR mineralized waste form can be produced. The documentation of the selection process of the three tank samples has been separately reported in RPP-48824, Sample Selection Process for Bench-Scale Steam Reforming Treatability Studies Using Hanford Waste Samples.

  12. Wide extragalactic (sub-)millimeter surveys with SCUBA and AzTEC

    NASA Astrophysics Data System (ADS)

    Aretxaga, I.; Hughes, D. H.; SHADES Collaboration; AzTEC Collaboration

    2009-05-01

    We summarize the present status of our knowledge of the millimeter galaxy population derived from extensive (sub-) millimeter extragalactic surveys like the SCUBA HAlf Degree Survey (SHADES), and the current status of the next generation of surveys traced with the AzTEC camera, that has, so far, surveyed more than 2 degrees at 1.1wavelengths.

  13. Rapid coating of AZ31 magnesium alloy with calcium deficient hydroxyapatite using microwave energy.

    PubMed

    Ren, Yufu; Zhou, Huan; Nabiyouni, Maryam; Bhaduri, Sarit B

    2015-04-01

    Due to their unique biodegradability, magnesium alloys have been recognized as suitable metallic implant materials for degradable bone implants and bioresorbable cardiovascular stents. However, the extremely high degradation rate of magnesium alloys in physiological environment has restricted its practical application. This paper reports the use of a novel microwave assisted coating technology to improve the in vitro corrosion resistance and biocompatibility of Mg alloy AZ31. Results indicate that a dense calcium deficient hydroxyapatite (CDHA) layer was uniformly coated on a AZ31 substrate in less than 10min. Weight loss measurement and SEM were used to evaluate corrosion behaviors in vitro of coated samples and of non-coated samples. It was seen that CDHA coatings remarkably reduced the mass loss of AZ31 alloy after 7days of immersion in SBF. In addition, the prompt precipitation of bone-like apatite layer on the sample surface during immersion demonstrated a good bioactivity of the CDHA coatings. Proliferation of osteoblast cells was promoted in 5days of incubation, which indicated that the CDHA coatings could improve the cytocompatibility of the AZ31 alloy. All the results suggest that the CDHA coatings, serving as a protective layer, can enhance the corrosion resistance and biological response of magnesium alloys. Furthermore, this microwave assisted coating technology could be a promising method for rapid surface modification of biomedical materials. PMID:25686961

  14. 78 FR 71641 - Notice of Realty Action: Direct Sale of Public Land in Graham County, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-29

    ... Bureau of Land Management Notice of Realty Action: Direct Sale of Public Land in Graham County, AZ AGENCY: Bureau of Land Management, Interior. ACTION: Notice of realty action. SUMMARY: The Bureau of Land Management (BLM), Safford Field Office (SFO), is considering a noncompetitive direct sale of approximately...

  15. 78 FR 15044 - Notice of Realty Action: Direct Sale of Public Land in Pinal County, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-08

    ... Bureau of Land Management Notice of Realty Action: Direct Sale of Public Land in Pinal County, AZ AGENCY: Bureau of Land Management, Interior. ACTION: Notice of realty action. SUMMARY: The Bureau of Land Management (BLM), Lower Sonoran Field Office (LSFO), proposes a noncompetitive direct sale of one land...

  16. Complete Genome Sequence of the Model Rhizosphere Strain Azospirillum brasilense Az39, Successfully Applied in Agriculture

    PubMed Central

    Rivera, Diego; Revale, Santiago; Molina, Romina; Gualpa, José; Puente, Mariana; Maroniche, Guillermo; Paris, Gastón; Baker, David; Clavijo, Bernardo; McLay, Kirsten; Spaepen, Stijn; Perticari, Alejandro; Vazquez, Martín; Wisniewski-Dyé, Florence; Watkins, Chris; Martínez-Abarca, Francisco; Vanderleyden, Jos

    2014-01-01

    We present the complete genome sequence of Azospirillum brasilense Az39, isolated from wheat roots in the central region of Argentina and used as inoculant in extensive and intensive agriculture during the last four decades. The genome consists of 7.39 Mb, distributed in six replicons: one chromosome, three chromids, and two plasmids. PMID:25059863

  17. Tank 241-AZ-101 steam bumping and settling Process Test report

    SciTech Connect

    Winkler, C.M.

    1995-12-04

    This report summarizes the process test in which the airlift circulators in Tank 241-AZ-101 were shutdown. The test was successful, in that no extreme temperature excursions occurred. Only general data was obtianed through the use of a gamma energy probe.

  18. 75 FR 44725 - Proposed Establishment of Class E Airspace; Clifton/Morenci, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ... Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR... 71 continues to read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR..., AZ. To accommodate aircraft using a new Area Navigation (RNAV) Global Positioning System...

  19. 76 FR 82113 - Amendment of Class E Airspace; Show Low, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-30

    ... controlled airspace at Show Low, AZ (76 FR 64041). Interested parties were invited to participate in this... Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The...

  20. 76 FR 64041 - Proposed Amendment of Class E Airspace; Show Low, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-17

    ... Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR... follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp... Federal Aviation Administration 14 CFR Part 71 Proposed Amendment of Class E Airspace; Show Low, AZ...

  1. 76 FR 2000 - Modification of Class E Airspace; Show Low, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-12

    ... Register a notice of proposed rulemaking to amend controlled airspace at Show Low, AZ (75 FR 65255... a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979.... 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in...

  2. 78 FR 65370 - Notice of Inventory Completion: Pima County Office of the Medical Examiner, Tucson, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-31

    .... ADDRESSES: Dr. Bruce Anderson, Forensic Anthropologist, PCOME, Tucson, AZ 85714, telephone (520) 243-8600... Office for forensic analysis. The Pinal County Medical Examiner, Dr Rebecca Hsu, transferred the remains to the Pima County Office of the Medical Examiner for examination by a forensic anthropologist....

  3. 75 FR 35504 - San Rafael Cattle Company; Habitat Conservation Plan; Santa Cruz County, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-22

    ... Fish and Wildlife Service San Rafael Cattle Company; Habitat Conservation Plan; Santa Cruz County, AZ AGENCY: Fish and Wildlife Service, Interior. ACTION: Notice of availability; Draft Low-Effect Habitat... habitat from specified actions conducted under the authority of the San Rafael Cattle Company. We...

  4. 75 FR 11554 - Notice of Intent to Repatriate Cultural Items: Museum of Northern Arizona, Flagstaff, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-11

    ... drawings and water color/pencil drawings, and are divided into three collections. The first collection was... watercolors of sacred Navajo Yei figures and deities; 22 water colors and/or pencil drawings depicting Navajo... and Big Star Way ceremonies. The second collection, by Ray Winnie, Lukachukai, AZ, circa...

  5. 75 FR 35122 - Approval of Noise Compatibility Program for Buckeye Municipal Airport, Town of Buckeye, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ..., Town of Buckeye, AZ AGENCY: Federal Aviation Administration, DOT. ACTION: Notice. SUMMARY: The Federal... Town of Buckeye under the provisions of 49 U.S.C. 47501 et seq. (formerly the Aviation Safety and Noise... maps submitted by the Town of Buckeye under Part 150 were in compliance with applicable...

  6. 78 FR 66267 - Safety Zone; HITS Triathlon Series; Colorado River; Lake Havasu, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-05

    ... Acronyms DHS Department of Homeland Security FR Federal Register NPRM Notice of Proposed Rulemaking A... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; HITS Triathlon Series; Colorado River; Lake... Bay in Lake Havasu, AZ. The safety zone will encompass the waters in the northern portion of...

  7. 78 FR 72006 - Establishment of Class D Airspace and Class E Airspace; Laguna AAF, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-02

    ... Register a notice of proposed rulemaking (NPRM) to establish controlled airspace at Laguna AAF, AZ (78 FR... Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a regulatory evaluation... read as follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E. O. 10854, 24 FR 9565, 3 CFR,...

  8. 78 FR 34558 - Modification of Class E Airspace; Clifton/Morenci, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ... Clifton/Morenci, AZ (78 FR 18269). Interested parties were invited to participate in this rulemaking... Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of... FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in 14 CFR...

  9. Creep of a thixoformed and heat treated AZ91 Mg-Al-Zn alloy

    SciTech Connect

    Spigarelli, S.

    2000-01-31

    The most frequently used cast magnesium alloy is AZ91, which contains 9% Al, 1% Zn and some Mn. Recently some studies have investigated the creep response of AZ91 ingots, pressure-die-casting and thixoformed specimens; die-cast and thixoformed alloys frequently show a similar microstructure, with equiaxed grains of {alpha} phase (solid solution of Al and Zn in Mg) and a brittle secondary phase, Mg{sub 17}Al{sub 12} ({beta} phase), on grain boundaries. The die-cast alloy has a very fine grain size (15 {micro}m) and a higher concentration of Mg{sub 17}Al{sub 12} than ingots; the thixoformed alloy exhibits large {alpha} phase globules of around 100 {micro}m and small {alpha}-particles of few microns in the eutectic region. The creep response of the die-cast and thixoformed alloys was found to be substantially equivalent, the creep strength of the die-cast material being one order of magnitude lower than that of the ingot. Thixoforming is one of the new processes that can be used to produce Magnesium alloy components for automotive applications. However, the typical structure of the thixoformed AZ91 exhibits a modest ductility, a property that can be substantially improved by subsequent solution treatment aimed at dissolving the brittle {beta} phase. The present study was undertaken to investigate the high-temperature response of thixoformed and solution treated AZ91.

  10. 75 FR 64708 - Reorganization of Foreign-Trade Zone 75 under Alternative Site Framework; Phoenix, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-20

    ...; Phoenix, AZ Pursuant to its authority under the Foreign-Trade Zones Act of June 18, 1934, as amended (19 U... Board adopted the alternative site framework (ASF) in December 2008 (74 FR 1170, 01/12/09; correction 74 FR 3987, 01/22/09) as an option for the establishment or reorganization of general-purpose...

  11. 78 FR 57545 - Proposed Establishment of Class D Airspace and Class E Airspace; Laguna AAF, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-19

    ... Proposed Establishment of Class D Airspace and Class E Airspace; Laguna AAF, AZ AGENCY: Federal Aviation... establish Class D airspace and Class E airspace at Laguna Army Air Field (AAF), (Yuma Proving Ground), Yuma... Regulations (14 CFR) part 71 by establishing Class D airspace from the surface to and including 1,700 feet...

  12. Study on High Strain Rate Compression Superplasticity of As-Extruded AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Lin, Fei; Li, Jie; Zhao, Hongwei; Sun, Lulu; Chen, Zhitong; Meng, Qingsen

    2013-07-01

    The grain size of as-extruded AZ31 magnesium alloy was refined by isothermal annealing pretreatment through orthogonal experiment. By using the Gleeble-3800 thermal simulator, the compression superplasticity of as-extruded AZ31 magnesium alloy was studied. The high strain rate superplastic compression was realized. The process parameters of the superplastic compression were established and the mechanism of the superplastic deformation was analyzed. The effects of deformation temperature and strain rate on the superplastic flow were investigated. The results indicated that at 250C-300C and strain rate at 110-2s-1, the true strain values were all more than 2.03. As the temperature was 300C and the strain rate was 110-2s-1-110 s-1, the true strain values were all more than 2.18. The results showed that the as-extruded AZ31 magnesium alloy being refined presented good compression superplasticity. The main mechanism for the superplastic compressive deformation of the as-extruded AZ31 magnesium alloy was grain-boundary sliding, meanwhile, dynamic recrystallization also played a harmonious role during the superplastic deformation.

  13. VizieR Online Data Catalog: AzTEC deep-field observations (Downes+, 2012)

    NASA Astrophysics Data System (ADS)

    Downes, T. P.; Welch, D.; Scott, K. S.; Austermann, J.; Wilson, G. W.; Yun, M. S.

    2013-02-01

    Instruments using arrays of many bolometers have become increasingly common in the past decade. The maps produced by such instruments typically include the filtering effects of the instrument as well as those from subsequent steps performed in the reduction of the data. Therefore interpretation of the maps is dependent upon accurately calculating the transfer function of the chosen reduction technique on the signal of interest. Many of these instruments use non-linear and iterative techniques to reduce their data because such methods can offer an improved signal-to-noise ratio over those that are purely linear, particularly for signals at scales comparable to that subtended by the array. We discuss a general approach for measuring the transfer function of principal component analysis on point sources that are small compared to the spatial extent seen by any single bolometer within the array. The results are applied to previously released AzTEC catalogues of the Cosmic Evolution Survey (COSMOS), Lockman Hole, Subaru XMM-Newton Deep Field, Great Observatories Origins Deep Survey (GOODS)-North and GOODS-South fields. Source flux density and noise estimates increase by roughly +10 per cent for fields observed while AzTEC was installed at the Atacama Submillimeter Telescope Experiment and +15-25 per cent while AzTEC was installed at the James Clerk Maxwell Telescope. Detection significance is, on average, unaffected by the revised technique. The revised photometry technique will be used in subsequent AzTEC releases. (5 data files).

  14. Radioisotope inventory of T101AZ thermocouple tree from riser 13D

    SciTech Connect

    Kessler, S.F., Westinghouse Hanford

    1996-06-12

    The radionuclide inventory for the thermocouple tree removed from tank T101-AZ riser 13D was estimated using measured {sup 137}Cs activity. This activity was measured by detectors as the tree was removed from the tank. Other radionuclide activities were estimated using the results of tank samples.

  15. 78 FR 25404 - Proposed Establishment of Class E Airspace; Grand Canyon, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-01

    ... ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does..., 40113, 40120; E.O. 10854, 24 FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation... Range/Distance Measuring Equipment (VOR/DME) navigation aid, Grand Canyon, AZ, to facilitate...

  16. 78 FR 40381 - Establishment of Class E Airspace; Grand Canyon, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-05

    ...) to establish controlled airspace at Grand Canyon, AZ (78 FR 25404). Interested parties were invited... Regulatory Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of... FR 9565, 3 CFR, 1959-1963 Comp., p. 389. Sec. 71.1 0 2. The incorporation by reference in 14 CFR...

  17. 75 FR 5115 - Temporary Concession Contract for Lake Mead National Recreation Area, AZ/NV

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-01

    ... concession contract for Lake Mead National Recreation Area. SUMMARY: Pursuant to 36 CFR 51.24, public notice... National Park Service Temporary Concession Contract for Lake Mead National Recreation Area, AZ/NV AGENCY... the conduct of certain visitor services within Lake Mead National Recreation Area, Arizona and...

  18. 76 FR 5398 - Notice of Temporary Closure of Selected Public Lands in La Paz County, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-31

    ...-330-07-02] Notice of Temporary Closure of Selected Public Lands in La Paz County, AZ AGENCY: Bureau of... its administration in La Paz County, Arizona. This action is being taken to protect persons, property... under the guidance of the La Paz County Emergency Medical Services and Fire, or the Arizona...

  19. 78 FR 3027 - Notice of Temporary Closures of Public Lands in La Paz County, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-15

    ...-10-05] Notice of Temporary Closures of Public Lands in La Paz County, AZ AGENCY: Bureau of Land... Lake Havasu Field Office in La Paz County, Arizona. This action is being taken to help ensure public... the La Paz County Emergency Medical Services and Fire, the Arizona Department of Public Safety, or...

  20. Validation of Airborne Visible-Infrared Imaging Spectrometer Data at Ray Mine, AZ

    NASA Technical Reports Server (NTRS)

    Lang, H.; Baloga, S.

    1999-01-01

    We validate 1997 Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) reflectance spectra covering 0.4 meu - 2.4 meu from a stable, flat mineralogically characterized man-made target at Ray Mine, AZ, the site for an EPA/NASA assessment of the utility of remote sensing for monitoring acid drainage from an active open pit mine.

  1. Study on fused/cast AZS refractories for deployment in vitrification of radioactive waste effluents

    NASA Astrophysics Data System (ADS)

    Sengupta, Pranesh; Mishra, R. K.; Soudamini, N.; Sen, D.; Mazumder, S.; Kaushik, C. P.; Ajithkumar, T. G.; Banerjee, K.

    2015-12-01

    'Fused/cast Al2O3-ZrO2-SiO2 (FC-AZS)' is being considered as 'glass contact refractory' within ceramic melters, to be used for nuclear waste immobilization. Microstructural analyses reveal random distributions of baddeleyite (ZrO2) within aluminosilicate (Al2SiO5) matrix. 27Al and 29Si NMR data suggest that within aluminosilicate matrix Al occurs in both 4- and 6-fold co-ordinations whereas Si prefers a 4-fold environment. Polydispersity of pores has been studied with small-angle neutron scattering (SANS) technique. Corrosion rates of FC-AZS within 6 M HNO3, simulated wastes (500 h exposure), and borosilicate melt (975 °C, 800 h exposure) are found to be 0.38 × 103 μmy-1, 0.13 × 103 μmy-1 and 4.75 × 103 μmy-1 respectively. A comparison of chemical interaction data clearly suggests that FC-AZS exhibits better chemical durability than AZC refractory (Al2O3-ZrO2-Cr2O3, also used for similar purpose). Thermal cycling studies indicate that FC-AZS retains structural integrity (including compressive strength and density) even up to 20 cycles.

  2. 78 FR 40503 - Notice of Realty Action: Direct Sale of Public Lands in Pima County, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-05

    ... Bureau of Land Management Notice of Realty Action: Direct Sale of Public Lands in Pima County, AZ AGENCY... approximately 5.96 acres in Pima County, Arizona. The parcel is being proposed for noncompetitive direct sale to... market value (FMV) of $83,440. DATES: Comments regarding the proposed direct sale must be received by...

  3. 75 FR 63066 - Establishment of Class E Airspace; Clifton/Morenci, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-14

    ... establish controlled airspace at Clifton/Morenci, AZ (75 FR 44725). Interested parties were invited to... Policies and Procedures (44 FR 11034; February 26, 1979); and (3) does not warrant preparation of a... follows: Authority: 49 U.S.C. 106(g), 40103, 40113, 40120; E. O. 10854, 24 FR 9565, 3 CFR, 1959-1963...

  4. Software Development Plan for the 241-AY and 241-AZ Tank Farm MICON automation system

    SciTech Connect

    Teats, M.C.

    1995-04-28

    Project W-030 will install a new tank ventilation system for the aging 241-AY and 241-AZ tank farm facilities. Controls for this system will be provided by a MICON distributed control system. This document defines the plan, deliverables, and schedule to develop software for the control system.

  5. 241-AZ-101 Waste Tank Color Video Camera System Shop Acceptance Test Report

    SciTech Connect

    WERRY, S.M.

    2000-03-23

    This report includes shop acceptance test results. The test was performed prior to installation at tank AZ-101. Both the camera system and camera purge system were originally sought and procured as a part of initial waste retrieval project W-151.

  6. 75 FR 11939 - DNS Electronics, Chandler, AZ; Notice of Termination of Investigation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-12

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF LABOR Employment and Training Administration DNS Electronics, Chandler, AZ; Notice of Termination of Investigation... a petition filed on May 27, 2009, by three workers on behalf of workers of DNS Electronics,...

  7. Mechanical and Wear Properties of Sb- and Y-Added Mg-9Al-1Zn (AZ91) Alloy

    NASA Astrophysics Data System (ADS)

    Boby, Arun; Srinivasan, A.; Pillai, U. T. S.; Pai, B. C.

    2015-09-01

    This paper studies the effect of Sb and Y additions on the microstructure and mechanical properties of the AZ91 alloy. The results indicate that the Sb and Y additions lead to the formation of Mg3Sb2 and Al2Y phases. These phases modify the morphology of the ?-Mg17Al12 phase, and hence refine the microstructure. The effects of Sb and Y additions on the aging behavior have also been investigated. Aging of the AZ91 alloy results in the formation of continuous and discontinuous types of precipitates. Whereas Sb and Y additions to AZ91 alloy suppresses the formation of discontinuous precipitate. The paper also reports the mechanical properties of as-cast and aged Sb-added AZ91-xY alloys for room and high temperatures. The optimum tensile properties are obtained with the alloy having the combined addition of 0.5 wt pct Sb and 0.6 wt pct Y. The fracture surface of AZ91-0.5Sb-0.6Y alloy reveals more quasi-cleavage type of failure with a cleavage fracture than the base alloy. At HT, the AZ91-0.5Sb-0.6Y alloy displays more cleavage facets connected with tearing ridges and shallow dimples than AZ91 alloy. Furthermore, it observed the improvement in wear resistance through the addition of Y. The worn surface reveals abrasion, oxidation, delamination, and plastic deformation wear mechanisms.

  8. Characterization of the first core sample of neutralized current acid waste from double-shell tank 101-AZ

    SciTech Connect

    Peterson, M E; Scheele, R D; Tingey, J M

    1989-09-01

    In FY 1989, Westinghouse Hanford Company (WHC) successfully obtained four core samples (totaling seven segments) of neutralized current acid waste (NCAW) from double-shell tanks (DSTs) 101-AZ and 102-AZ. A segment was a 19-in.-long and 1-in.-diameter cylindrical sample of waste. A core sample consisted of enough 19-in.-long segments to obtain the waste of interest. Three core samples were obtained from DST 101-AZ and one core sample from DST 102-AZ. Two DST 101-AZ core samples consisted of two segments per core, and the third core sample consisted of only one segment. The third core consisted of the solids from the bottom of the tank and was used to determine the relative abrasiveness of this NCAW. The DST 102-AZ core sample consisted of two segments. The core samples were transported to the Pacific Northwest Laboratory (PNL), where the waste was extruded from its sampler and extensively characterized. A characterization plan was followed that simulated the processing of the NCAW samples through retrieval, pretreatment and vitrification process steps. Physical, rheological, chemical and radiochemical properties were measured throughout the process steps. The characterization of the first core sample from DST 101-AZ was completed, and the results are provided in this report. The results for the other core characterizations will be reported in future reports. 3 refs., 13 figs., 10 tabs.

  9. Tank 241-AZ-101 criticality assessment resulting from pump jet mixing: Sludge mixing simulation

    SciTech Connect

    Onishi, Y.; Recknagle, K.

    1997-04-01

    Tank 241-AZ-101 (AZ-101) is one of 28 double-shell tanks located in the AZ farm in the Hanford Site`s 200 East Area. The tank contains a significant quantity of fissile materials, including an estimated 9.782 kg of plutonium. Before beginning jet pump mixing for mitigative purposes, the operations must be evaluated to demonstrate that they will be subcritical under both normal and credible abnormal conditions. The main objective of this study was to address a concern about whether two 300-hp pumps with four rotating 18.3-m/s (60-ft/s) jets can concentrate plutonium in their pump housings during mixer pump operation and cause a criticality. The three-dimensional simulation was performed with the time-varying TEMPEST code to determine how much the pump jet mixing of Tank AZ-101 will concentrate plutonium in the pump housing. The AZ-101 model predicted that the total amount of plutonium within the pump housing peaks at 75 g at 10 simulation seconds and decreases to less than 10 g at four minutes. The plutonium concentration in the entire pump housing peaks at 0.60 g/L at 10 simulation seconds and is reduced to below 0.1 g/L after four minutes. Since the minimum critical concentration of plutonium is 2.6 g/L, and the minimum critical plutonium mass under idealized plutonium-water conditions is 520 g, these predicted maximums in the pump housing are much lower than the minimum plutonium conditions needed to reach a criticality level. The initial plutonium maximum of 1.88 g/L still results in safety factor of 4.3 in the pump housing during the pump jet mixing operation.

  10. Respiratory Syncytial Virus Inhibitor AZ-27 Differentially Inhibits Different Polymerase Activities at the Promoter

    PubMed Central

    Noton, Sarah L.; Nagendra, Kartikeya; Dunn, Ewan F.; Mawhorter, Michael E.; Yu, Qin

    2015-01-01

    ABSTRACT Respiratory syncytial virus (RSV) is the leading cause of pediatric respiratory disease. RSV has an RNA-dependent RNA polymerase that transcribes and replicates the viral negative-sense RNA genome. The large polymerase subunit (L) has multiple enzymatic activities, having the capability to synthesize RNA and add and methylate a cap on each of the viral mRNAs. Previous studies (H. Xiong et al., Bioorg Med Chem Lett, 23:6789–6793, 2013, http://dx.doi.org/10.1016/j.bmcl.2013.10.018; C. L. Tiong-Yip et al., Antimicrob Agents Chemother, 58:3867–3873, 2014, http://dx.doi.org/10.1128/AAC.02540-14) had identified a small-molecule inhibitor, AZ-27, that targets the L protein. In this study, we examined the effect of AZ-27 on different aspects of RSV polymerase activity. AZ-27 was found to inhibit equally both mRNA transcription and genome replication in cell-based minigenome assays, indicating that it inhibits a step common to both of these RNA synthesis processes. Analysis in an in vitro transcription run-on assay, containing RSV nucleocapsids, showed that AZ-27 inhibits synthesis of transcripts from the 3′ end of the genome to a greater extent than those from the 5′ end, indicating that it inhibits transcription initiation. Consistent with this finding, experiments that assayed polymerase activity on the promoter showed that AZ-27 inhibited transcription and replication initiation. The RSV polymerase also can utilize the promoter sequence to perform a back-priming reaction. Interestingly, addition of AZ-27 had no effect on the addition of up to three nucleotides by back-priming but inhibited further extension of the back-primed RNA. These data provide new information regarding the mechanism of inhibition by AZ-27. They also suggest that the RSV polymerase adopts different conformations to perform its different activities at the promoter. IMPORTANCE Currently, there are no effective antiviral drugs to treat RSV infection. The RSV polymerase is an attractive target for drug development, but this large enzymatic complex is poorly characterized, hampering drug development efforts. AZ-27 is a small-molecule inhibitor previously shown to target the RSV large polymerase subunit (C. L. Tiong-Yip et al., Antimicrob Agents Chemother, 58:3867–3873, 2014, http://dx.doi.org/10.1128/AAC.02540-14), but its inhibitory mechanism was unknown. Understanding this would be valuable both for characterizing the polymerase and for further development of inhibitors. Here, we show that AZ-27 inhibits an early stage in mRNA transcription, as well as genome replication, by inhibiting initiation of RNA synthesis from the promoter. However, the compound does not inhibit back priming, another RNA synthesis activity of the RSV polymerase. These findings provide insight into the different activities of the RSV polymerase and will aid further development of antiviral agents against RSV. PMID:25995255

  11. Analysis of Human Histone H2AZ Deposition In Vivo Argues against Its Direct Role in Epigenetic Templating Mechanisms

    PubMed Central

    Viens, Antoine; Mechold, Undine; Brouillard, Franck; Gilbert, Cristele; Leclerc, Philippe; Ogryzko, Vasily

    2006-01-01

    Chromatin is considered to be a principal carrier of epigenetic information due to the ability of alternative chromatin states to persist through generations of cell divisions and to spread on DNA. Replacement histone variants are novel candidates for epigenetic marking of chromatin. We developed a novel approach to analyze the chromatin environment of nucleosomes containing a particular replacement histone. We applied it to human H2AZ, one of the most studied alternative histones. We find that neither H2AZ itself nor other features of the H2AZ-containing nucleosome spread to the neighboring nucleosomes in vivo, arguing against a role for H2AZ as a self-perpetuating epigenetic mark. PMID:16809769

  12. Analysis of human histone H2AZ deposition in vivo argues against its direct role in epigenetic templating mechanisms.

    PubMed

    Viens, Antoine; Mechold, Undine; Brouillard, Franck; Gilbert, Cristele; Leclerc, Philippe; Ogryzko, Vasily

    2006-07-01

    Chromatin is considered to be a principal carrier of epigenetic information due to the ability of alternative chromatin states to persist through generations of cell divisions and to spread on DNA. Replacement histone variants are novel candidates for epigenetic marking of chromatin. We developed a novel approach to analyze the chromatin environment of nucleosomes containing a particular replacement histone. We applied it to human H2AZ, one of the most studied alternative histones. We find that neither H2AZ itself nor other features of the H2AZ-containing nucleosome spread to the neighboring nucleosomes in vivo, arguing against a role for H2AZ as a self-perpetuating epigenetic mark. PMID:16809769

  13. 76 FR 15936 - Designation for the Owensboro, KY; Bloomington, IL; Iowa Falls, IA; Casa Grande, AZ; Fargo, ND...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-22

    ... hours (7 CFR 1.27(c)). SUPPLEMENTARY INFORMATION: In the August 30, 2010, Federal Register (75 FR 52925..., IL; Iowa Falls, IA; Casa Grande, AZ; Fargo, ND; Grand Forks, ND; and Plainview, TX Areas...

  14. AZ-101 Mixer Pump Demonstration Data Acquisition System and Gamma Cart Data Acquisition Control System Software Configuration Management Plan

    SciTech Connect

    WHITE, D.A.

    1999-12-29

    This Software Configuration Management Plan (SCMP) provides the instructions for change control of the AZ1101 Mixer Pump Demonstration Data Acquisition System (DAS) and the Sludge Mobilization Cart (Gamma Cart) Data Acquisition and Control System (DACS).

  15. Jerusalem: City of Dreams, City of Sorrows

    ERIC Educational Resources Information Center

    Ricks, Thomas

    2011-01-01

    Jerusalem is more than an intriguing global historical city; it is a classroom for liberal learning and international understanding. It had never been a city of one language, one religion and one culture. Looking at the origins of Jerusalem's name indicates its international and multicultural nature. While Israelis designate Jerusalem as their…

  16. H2A.Z landscapes and dual modifications in pluripotent and multipotent stem cells underlie complex genome regulatory functions

    PubMed Central

    2012-01-01

    Background The histone variant H2A.Z has been implicated in nucleosome exchange, transcriptional activation and Polycomb repression. However, the relationships among these seemingly disparate functions remain obscure. Results We mapped H2A.Z genome-wide in mammalian ES cells and neural progenitors. H2A.Z is deposited promiscuously at promoters and enhancers, and correlates strongly with H3K4 methylation. Accordingly, H2A.Z is present at poised promoters with bivalent chromatin and at active promoters with H3K4 methylation, but is absent from stably repressed promoters that are specifically enriched for H3K27 trimethylation. We also characterized post-translational modification states of H2A.Z, including a novel species dually-modified by ubiquitination and acetylation that is enriched at bivalent chromatin. Conclusions Our findings associate H2A.Z with functionally distinct genomic elements, and suggest that post-translational modifications may reconcile its contrasting locations and roles. PMID:23034477

  17. Project W-314 specific test and evaluation plan for AZ tank farm upgrades

    SciTech Connect

    Hays, W.H.

    1998-08-12

    The purpose of this Specific Test and Evaluation Plan (STEP) is to provide a detailed written plan for the systematic testing of modifications made by the addition of the SN-631 transfer line from the AZ-O1A pit to the AZ-02A pit by the W-314 Project. The STEP develops the outline for test procedures that verify the system`s performance to the established Project design criteria. The STEP is a lower tier document based on the W-314 Test and Evaluation P1 an (TEP). Testing includes Validations and Verifications (e.g., Commercial Grade Item Dedication activities, etc), Factory Tests and Inspections (FTIs), installation tests and inspections, Construction Tests and Inspections (CTIs), Acceptance Test Procedures (ATPs), Pre-Operational Test Procedures (POTPs), and Operational Test Procedures (OTPs). The STEP will be utilized in conjunction with the TEP for verification and validation.

  18. Study on hydrogen removal of AZ91 alloys using ultrasonic argon degassing process.

    PubMed

    Liu, Xuan; Zhang, Zhiqiang; Hu, Wenyi; Le, Qichi; Bao, Lei; Cui, Jianzhong; Jiang, Jiajia

    2015-09-01

    Argon degassing, ultrasonic degassing and a novel ultrasonic argon degassing treatment were applied for the hydrogen removal of AZ91 magnesium alloy. The hydrogen concentration, microstructures and mechanical properties have also been investigated. AZ91 alloys contains a high hydrogen concentration. The mechanical properties of the as-cast alloy are much improved using degassing process, which should be mainly attributed to the hydrogen removal. Among the three degassing process, the ultrasonic argon treatment is a high efficient process both for hydrogen removal and microstructure refining. One hand, ultrasonic wave could break up the purged argon bubble to improve the degassing efficiency of these bubbles. On the other hand, ultrasound could also generate many cavitation bubbles in the melt, which should account for the microstructure refinement. The ultrasonic argon treatment involves dynamics between the ascending argon bubbles and ultrasonic effects, such as cavitation and streaming, etc. PMID:25649834

  19. An organic chromium-free conversion coating on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoming; Li, Guangyu; Lian, Jianshe; Jiang, Qing

    2008-12-01

    Traditional conversion coatings on magnesium alloys are usually immersed in a solution containing hexavalent chromium compounds. However, the replacement treatments have been proposed by the present environmental driving to eliminate hexavalent chromium. In this work, a tannic acid based conversion coating on AZ91D magnesium alloy was obtained by treatment in a solution containing tannic acid and ammonium metavanadate. SEM, XPS and IR were used to determine the morphology and structure of the conversion coatings. Continuous and uniform conversion coating was deposited on AZ91D alloy and the main components of the coatings were Al 2O 3, MgF 2 and penta-hydroxy benzamide-magnesium complex. The formation mechanism of the coating was discussed. Polarization measurement and salt spray test showed that the corrosion resistance of the conversion coating was much higher than that of traditional chromate conversion coating.

  20. An Investigation to Double Hit Deformation Behavior of AZ31 Magnesium Alloy

    SciTech Connect

    Shamsi, M.; Hanzaki, A. Zarei; Naei, H.

    2007-04-07

    In recent years magnesium alloys have been used in different industries due to their outstanding properties. The hot deformation processes are recognized to be the most applicable forming routes for these alloys. These are usually performed through multi-stage straining. Accordingly the static restoration processes may play important roles on their final microstructure and mechanical properties. In the present work double hit compression tests were applied on AZ31 magnesium alloy. The results were analyzed relying on the fractional softening relationship. The effects of strain rate and inter-pass time were discussed. Microstructural observations were addressed to describe the effects of static recrystallization on the double hit deformation behavior of AZ31 alloy.

  1. Evaluation of AY/AZ tank farm ventilation system during aging waste retrieval operations

    SciTech Connect

    Wong, J.J.; Waters, E.D.

    1995-01-01

    Waste Management is currently planning to demonstrate mobilization of radioactive waste sludges in Tank 101-AZ beginning in October 1991. The retrieval system being designed will utilize mixer pumps that generate high-velocity, high-volume submerged liquid jets to mobilize settled solids. There is concern that these jets may also generate radioactive aerosols, some of which may be carried into the tank Ventilation system. The purpose of this study is to determine if the current AY/AZ ventilation system or the proposed ventilation system upgrade (Project W-030) will provide adequate deentrainment of liquid and solid aerosols during mixer pump operations, or if the radioactive aerosols will overload the HEPA filters.

  2. Surface characterization and cytocompatibility evaluation of silanized magnesium alloy AZ91 for biomedical applications

    NASA Astrophysics Data System (ADS)

    Witecka, Agnieszka; Yamamoto, Akiko; Dybiec, Henryk; Swieszkowski, Wojciech

    2012-12-01

    Mg alloys with high Al contents have superior corrosion resistance in aqueous environments, but poor cytocompatibility compared to that of pure Mg. We have silanized the cast AZ91 alloy to improve its cytocompatibility using five different silanes: ethyltriethoxysilane (S1), 3-aminopropyltriethoxysilane (S2), 3-isocyanatopyltriethoxysilane (S3), phenyltriethoxysilane (S4) and octadecyltriethoxysilane (S5). The surface hydrophilicity/hydrophobicity was evaluated by water contact angle measurements. X-ray photoelectron analysis was performed to investigate the changes in surface states and chemical composition. All silane reagents increased adsorption of the albumin to the modified surface. In vitro cytocompatibility evaluation revealed that silanization improved cell growth on AZ91 modified by silane S1. Measurement of the concentration of Mg2+ ions released during the cell culture indicated that silanization does not affect substrate degradation.

  3. Corrosion Behavior of AZ91D Magnesium Alloy in Three Different Physiological Environments

    NASA Astrophysics Data System (ADS)

    Zhou, Juncen; Li, Qing; Zhang, Haixiao; Chen, Funan

    2014-01-01

    Magnesium alloys have been considered as promising biomedical materials and were studied in different physiological environments. In this work, corrosion behavior of AZ91D magnesium alloy in artificial saliva, simulated body fluid (SBF), and 3.5 wt.% NaCl solution was investigated using electrochemical techniques and a short-term immersion test. In contrast with other physiological environments, the amount of aggressive ions in artificial saliva is small. In addition, a protective film is formed on the surface of samples in artificial saliva. Experimental results suggest that corrosion resistance of AZ91D magnesium alloy in artificial saliva is better than that in c-SBF and 3.5 wt.% NaCl solution.

  4. What Is Clean Cities?

    SciTech Connect

    Not Available

    2007-08-01

    This Clean Cities Program fact sheet describes the purpose and scope of this DOE program. Clean Cities facilitates the use of alternative and advanced fuels and vehicles to displace petroleum in the transportation sector.

  5. Test plan: Laboratory-scale testing of the first core sample from Tank 102-AZ

    SciTech Connect

    Morrey, E.V.

    1996-03-01

    The overall objectives of the Radioactive Process/Product Laboratory Testing (RPPLT), WBS 1.2.2.05.05, are to confirm that simulated HWVP feed and glass are representative of actual radioactive HWVP feed and glass and to provide radioactive leaching and glass composition data to WFQ. This study will provide data from one additional NCAW core sample (102-AZ Core 1) for these purposes.

  6. Best Practices Case Study: John Wesley Miller Companies - Armory Park Del Sol, Tucson, AZ

    SciTech Connect

    2009-10-01

    Case study of John Wesley Miller Companies, who built two net zero energy homes plus 97 other solar homes in Tucson, AZ. Masonry block walls with rigid foam exterior sheathing, rigid foam over the roof deck plus R-38 in the attic, ducts in conditioned space, 4.2 kW and 5.7 kW photovoltaics and solar water heating yielded HERS scores of 0 on the two homes.

  7. Effect of ECAP on microstructure and mechanical properties of cast AZ91 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Chung, C. W.; Ding, R. G.; Chiu, Y. L.; Gao, W.

    2010-07-01

    An as-cast AZ91 magnesium alloy was processed by Equal Channel Angular Pressing (ECAP) at 320C. The microstructure and mechanical properties were studied. It has been found that ECAP refines both the grains and precipitates, thus modifies the strength and ductility of the processed alloy. After the first pass of ECAP, the yield stress improves significantly from 71 MPa to 140 MPa.

  8. Evaluation results for the positive deep-UV resist AZ DX 46

    NASA Astrophysics Data System (ADS)

    Spiess, Walter; Lynch, Thomas J.; Le Cornec, Charles; Escher, Gary C.; Kinoshita, Yoshiaki; Kochan, John; Kudo, Takanori; Masuda, Seiya; Mourier, Thierry; Nozaki, Yuko; Olson, Setha G.; Okazaki, Hiroshi; Padmanaban, Munirathna; Pawlowski, Georg; Przybilla, Klaus J.; Roeschert, Horst; Suehiro, Natusmi; Vinet, Francoise; Wengenroth, Horst

    1994-05-01

    This contribution emphasizes resist application site by communicating lithographic results for AZ DX 46, obtained using the GCA XLS 7800/31 stepper, NA equals 0.53, equipped with krypton fluoride excimer laser ((lambda) equals 248 nm), model 4500 D, as exposure source, delivered by Cymer Laser Technologies. As far as delay time experiments are concerned ASM-L PAS 5500/70 stepper, NA equals 0.42, was used in combination with Lambda Physik excimer laser, model 248 L.

  9. VizieR Online Data Catalog: AzTEC/ASTE source catalogue (Aretxaga+, 2011)

    NASA Astrophysics Data System (ADS)

    Aretxaga, I.; Wilson, G. W.; Aguilar, E.; Alberts, S.; Scott, K. S.; Scoville, N.; Yun, M. S.; Austermann, J.; Downes, T. P.; Ezawa, H.; Hatsukade, B.; Hughes, D. H.; Kawabe, R.; Kohno, K.; Oshima, T.; Perera, T. A.; Tamura, Y.; Zeballos, M.

    2013-02-01

    We imaged a 2800 arcmin2 field centred at right ascension RA(J2000.0)=10:00:30.00 and declination DE(J2000.0)=2:14.00 with AzTEC mounted on the 10-m ASTE, located at 4800m in the Atacama Desert of Chile. The survey was carried out from 2008 October 20 to November 30. (1 data file).

  10. AzTEC 1.1 mm Observations of the MBM12 Molecular Cloud

    NASA Astrophysics Data System (ADS)

    Kim, M. J.; Kim, S.; Youn, S.; Yun, M. S.; Wilson, G. W.; Aretxaga, I.; Williams, J. P.; Hughes, D. H.; Humphrey, A.; Austermann, J. E.; Perera, T. A.; Mauskopf, P. D.; Magnani, L.; Kang, Y.-W.

    2012-02-01

    We present 1.1 mm observations of the dust continuum emission from the MBM12 high-latitude molecular cloud observed with the Astronomical Thermal Emission Camera (AzTEC) mounted on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. We surveyed 6.34 deg2 centered on MBM12, making this the largest area that has ever been surveyed in this region with submillimeter and millimeter telescopes. Eight secure individual sources were detected with a signal-to-noise ratio of over 4.4. These eight AzTEC sources can be considered to be real astronomical objects compared to the other candidates based on calculations of the false detection rate. The distribution of the detected 1.1 mm sources or compact 1.1 mm peaks is spatially anti-correlated with that of the 100 ?m emission and the 12CO emission. We detected the 1.1 mm dust continuum emitting sources associated with two classical T Tauri stars, LkH?262 and LkH?264. Observations of spectral energy distributions (SEDs) indicate that LkH?262 is likely to be Class II (pre-main-sequence star), but there are also indications that it could be a late Class I (protostar). A flared disk and a bipolar cavity in the models of Class I sources lead to more complicated SEDs. From the present AzTEC observations of the MBM12 region, it appears that other sources detected with AzTEC are likely to be extragalactic and located behind MBM12. Some of these have radio counterparts and their star formation rates are derived from a fit of the SEDs to the photometric evolution of galaxies in which the effects of a dusty interstellar medium have been included.

  11. Prebake and post-exposure bake effects on the dissolution of AZ-PF

    NASA Astrophysics Data System (ADS)

    Krasnoperova, Azalia A.; Reilly, Michael T.; Turner, S.; Ocola, L.; Cerrina, Franco

    1993-09-01

    We have performed experiments to study the kinetics of dissolution of the positive chemically amplified resist AZ-PF (Hoechst AG). The resist dissolution in exposed regions was shown to have non-linear time dependence, with a delay time strongly dependent on prebake and post- exposure bake conditions. Effect of the presence of a low-solubility surface layer on patterning of submicron features as well as on roughness of the developed film has been demonstrated.

  12. AzTEC 1.1 mm OBSERVATIONS OF THE MBM12 MOLECULAR CLOUD

    SciTech Connect

    Kim, M. J.; Kim, S.; Youn, S.; Kang, Y.-W.; Yun, M. S.; Wilson, G. W.; Aretxaga, I.; Hughes, D. H.; Humphrey, A.; Williams, J. P.; Austermann, J. E.; Perera, T. A.; Mauskopf, P. D.; Magnani, L.

    2012-02-10

    We present 1.1 mm observations of the dust continuum emission from the MBM12 high-latitude molecular cloud observed with the Astronomical Thermal Emission Camera (AzTEC) mounted on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. We surveyed 6.34 deg{sup 2} centered on MBM12, making this the largest area that has ever been surveyed in this region with submillimeter and millimeter telescopes. Eight secure individual sources were detected with a signal-to-noise ratio of over 4.4. These eight AzTEC sources can be considered to be real astronomical objects compared to the other candidates based on calculations of the false detection rate. The distribution of the detected 1.1 mm sources or compact 1.1 mm peaks is spatially anti-correlated with that of the 100 {mu}m emission and the {sup 12}CO emission. We detected the 1.1 mm dust continuum emitting sources associated with two classical T Tauri stars, LkH{alpha}262 and LkH{alpha}264. Observations of spectral energy distributions (SEDs) indicate that LkH{alpha}262 is likely to be Class II (pre-main-sequence star), but there are also indications that it could be a late Class I (protostar). A flared disk and a bipolar cavity in the models of Class I sources lead to more complicated SEDs. From the present AzTEC observations of the MBM12 region, it appears that other sources detected with AzTEC are likely to be extragalactic and located behind MBM12. Some of these have radio counterparts and their star formation rates are derived from a fit of the SEDs to the photometric evolution of galaxies in which the effects of a dusty interstellar medium have been included.

  13. Comparison of simulants to actual neutralized current acid waste: Process and product testing of three NCAW core samples from Tanks 101-AZ and 102-AZ

    SciTech Connect

    Morrey, E.V.; Tingey, J.M.

    1996-04-01

    A vitrification plant is planned to process the high-level waste (HLW) solids from Hanford Site tanks into canistered glass logs for disposal in a national repository. Programs have been established within the Pacific Northwest Laboratory Vitrification Technology Development (PVTD) Project to test and model simulated waste to support design, feed processability, operations, permitting, safety, and waste-form qualification. Parallel testing with actual radioactive waste is being performed on a laboratory-scale to confirm the validity of using simulants and glass property models developed from simulants. Laboratory-scale testing has been completed on three radioactive core samples from tanks 101-AZ and 102-AZ containing neutralized current acid waste (NCAW), which is one of the first waste types to be processed in the high-level waste vitrification plant under a privatization scenario. Properties of the radioactive waste measured during process and product testing were compared to simulant properties and model predictions to confirm the validity of simulant and glass property models work. This report includes results from the three NCAW core samples, comparable results from slurry and glass simulants, and comparisons to glass property model predictions.

  14. Stamping of Thin-Walled Structural Components with Magnesium Alloy AZ31 Sheets

    SciTech Connect

    Chen, F.-K.; Chang, C.-K.

    2005-08-05

    In the present study, the stamping process for manufacturing cell phone cases with magnesium alloy AZ31 sheets was studied using both the experimental approach and the finite element analysis. In order to determine the proper forming temperature and set up a fracture criterion, tensile tests and forming limit tests were first conducted to obtain the mechanical behaviors of AZ31 sheets at various elevated temperatures. The mechanical properties of Z31 sheets obtained from the experiments were then adopted in the finite element analysis to investigate the effects of the process parameters on the formability of the stamping process of cell phone cases. The finite element simulation results revealed that both the fracture and wrinkle defects could not be eliminated at the same time by adjusting blank-holder force or blank size. A drawbead design was then performed using the finite element simulations to determine the size and the location of drawbead required to suppress the wrinkle defect. An optimum stamping process, including die geometry, forming temperature, and blank dimension, was then determined for manufacturing the cell phone cases. The finite element analysis was validated by the good agreement between the simulation results and the experimental data. It confirms that the cell phone cases can be produced with magnesium alloy AZ31 sheet by the stamping process at elevated temperatures.

  15. A cellular automaton model for microstructural simulation of friction stir welded AZ91 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Akbari, Mostafa; Asadi, Parviz; Besharati Givi, MohammadKazem; Zolghadr, Parisa

    2016-03-01

    To predict the grain size and microstructure evolution during friction stir welding (FSW) of AZ91 magnesium alloy, a finite element model (FEM) is developed based on the combination of a cellular automaton model and the Kocks  ‑  Mecking and Laasraoui–Jonas models. First, according to the flow stress curves and using the Kocks  ‑  Mecking model, the hardening and recovery parameters and the strain rate sensitivity were calculated. Next, an FEM model was established in Deform-3D software to simulate the FSW of AZ91 magnesium alloy. The results of the FEM model are used in microstructure evolution models to predict the grain size and microstructure of the weld zone. There is a good agreement between the simulated and experimental microstructures, and the proposed model can simulate the dynamic recrystallization (DRX) process during FSW of AZ91 alloy. Moreover, microstructural properties of different points in the SZ as well as the effect of the w/v parameter on the grain size and microstructure are considered.

  16. Effects of Rare Earth Element Additions on the Impression Creep Behavior of AZ91 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Kabirian, F.; Mahmudi, R.

    2009-09-01

    The effects of 1, 2, and 3 wt pct rare earth (RE) element additions on the microstructure and creep behavior of cast AZ91 Mg alloy were investigated by impression tests. The tests were carried out under constant punching stress in the range 200 to 650 MPa at temperatures in the range 425 to 525 K. Analysis of the data showed that for all loads and temperatures, the AZ91-2RE alloy had the lowest creep rates and, thus, the highest creep resistance among all materials tested. This is attributed to the formation of Al11RE3 with a branched morphology, reduction in the volume fraction of the eutectic ?-Mg17Al12 phase, and solid solution hardening effects of Al in the Mg matrix. The stress exponents and activation energies were the same for all alloy systems studied, 5.3 to 6.5 and 90 to 120 kJ mol-1, respectively, with the exception that the activation energy for the AZ91-3RE system was 102 to 126 kJ mol-1. An observed decreasing trend of creep-activation energy with stress suggests that two parallel mechanisms of lattice and pipe diffusion-controlled dislocation climb are competing. Dislocation climb controlled by dislocation pipe diffusion is controlling at high stresses, whereas climb of edge dislocations is the controlling mechanism at low stresses.

  17. H2A.Z helps genes remember their history so we can remember ours.

    PubMed

    Zovkic, Iva B; Walters, Brandon J

    2015-06-01

    Histone variant exchange is a novel epigenetic regulator of cognition. We speculate that H2A.Z, a variant of canonical histone H2A, exerts unique effects on transcription during distinct stages of memory formation, ultimately acting to maintain memory of previous transcriptional states and poise genes for re-activation. Hippocampus-dependent memory formation is initiated by transient expression of memory-related genes, which support the storage of recently acquired memories. Soon after, memories undergo systems consolidation, which transfers memories from the hippocampus to the cortex for long-term storage, and requires ongoing re-activation of memory-related genes. We speculate that learning-induced H2A.Z eviction from nucleosomes initially contributes to stimulus-induced transcriptional induction needed for the initial process of memory consolidation. During systems consolidation, we speculate that delayed incorporation of H2A.Z into nucleosomes of memory-related genes in the cortex is needed to poise genes for rapid re-activation, thus supporting the long-term process of memory stabilization. PMID:25880368

  18. Profiling gene expression in citrus fruit calyx abscission zone (AZ-C) treated with ethylene.

    PubMed

    Cheng, Chunzhen; Zhang, Lingyun; Yang, Xuelian; Zhong, Guangyan

    2015-10-01

    On-tree storage and harvesting of mature fruit account for a large proportion of cost in the production of citrus, and a reduction of the cost would not be achieved without a thorough understanding of the mechani sm of the mature fruit abscission. Genome-wide gene expression changes in ethylene-treated fruit calyx abscission zone (AZ-C) of Citrus sinensis cv. Olinda were therefore investigated using a citrus genome array representing up to 33,879 citrus transcripts. In total, 1313 and 1044 differentially regulated genes were identified in AZ-C treated with ethylene for 4 and 24h, respectively. The results showed that mature citrus fruit abscission commenced with the activation of ethylene signal transduction pathway that led to the activation of ethylene responsive transcription factors and the subsequent transcriptional regulation of a large set of ethylene responsive genes. Significantly down-regulated genes included those of starch/sugar biosynthesis, transportation of water and growth promoting hormone synthesis and signaling, whereas significantly up-regulated genes were those involved in defense, cell wall degradation, and secondary metabolism. Our data unraveled the underlying mechanisms of some known important biochemical events occurring at AZ-C and should provide informative suggestions for future manipulation of the events to achieve a controllable abscission for mature citrus fruit. PMID:25948248

  19. Synthesis of dittmarite/Mg(OH)2 composite coating on AZ31 using hydrothermal treatment

    NASA Astrophysics Data System (ADS)

    Zhao, Qing; Mahmood, Waqas; Zhu, Yanying

    2016-03-01

    In this work, we have used hydrothermal method for the synthesis of dittmarite/Mg(OH)2 composite (DMC) layer on AZ31 alloy of magnesium. The synthesized coating was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectroscopy (EDS). In a test immersion into the Hank's mixture for 31 days, the synthesized coating inhibited corrosion of AZ31 significantly and the amorphous calcium apatite precursor deposited on the coating surface. In another tape test, we noticed strong adhesion between the coating and substrate that eventually concludes that the synthesized coating is hydrophilic and a promising candidate to be used in the absorbable implant materials. Besides, the cytotoxicity of the AZ31 alloy with DMC coating, grown under different conditions on L-929 cells in vitro was examined indirectly through the growth inhibition method (MTT assay). The cytotoxicity of the deposited coating lie between 0 ∼ 1 that indicates it as a promising biomaterial.

  20. Evaluation of corrosion resistance of casting magnesium alloy AZ31 in NaCl solutions

    NASA Astrophysics Data System (ADS)

    Przondziono, J.; Walke, W.; Szala, J.; Hadasik, E.; Wieczorek, J.

    2011-05-01

    The results of tests of corrosion resistance of casting magnesium alloy AZ31 in NaCl solutions of 0,012 M concentration have been presented. Electrochemical measurements were carried out with application of VoltaLabPGP201 system by Radiometer. On the ground of registered polarisation curves, typical features characterising alloy resistance to electrochemical corrosion, i.e. corrosion potential, polarisation resistance, corrosion current density and corrosion rate, were determined. Electrochemical impedance spectroscopy was applied for evaluation of phenomena that occurred on the surface of the tested alloy. Resistance to corrosion was tested by means of immersion method for 15 days. By means of scanning electron microscope with field emission FE SEM S-4200 Hitachi in cooperation with spectrometer EDS Voyager 3500 Noran Instruments, quantitative and qualitative analysis of chemical composition in micro-zones was made. The study also presents the results of measurements of geometrical features of AZ31 alloy surface after corrosion tests. The results of the tests show undoubtedly deterioration of corrosion properties of magnesium alloy AZ31 together with the increase in molar concentration of NaCl solution.

  1. Physical Properties of AZ91D Measured Using the Draining Crucible Method: Effect of SF6

    NASA Astrophysics Data System (ADS)

    Roach, Steven J.; Henein, Hani

    2012-03-01

    The draining crucible (DC) technique was used for measurements on AZ91D under Ar and SF6. The DC technique is a new method developed to simultaneously measure the physical properties of fluids, the density, surface tension, and viscosity. Based on the relationship between the height of a metal in a crucible and the outgoing flow rate, a multi-variable regression is used to calculate the values of these fluid properties. Experiments performed with AZ91D at temperatures from 923 K to 1173 K indicate that under argon, the surface tension (N m-1) and density (kg m-3) are [0.63 - 2.13 10-4 ( T - T L)] and [1656 - 0.158 ( T - T L)], respectively. The viscosity (Pa s) has been determined to be [1.455 10-3 - 1.209 10-5 ( T - T L)] over the temperature range from 921 K to 967 K superheat. Above 967 K, the viscosity of the alloy under argon seems to be constant at (2.66 10-4 8.67 10-5) Pa s. SF6 reduces the surface tension of AZ91D.

  2. Strategies to reduce the harmful effects of extreme heat events: a four-city study.

    PubMed

    White-Newsome, Jalonne L; McCormick, Sabrina; Sampson, Natalie; Buxton, Miatta A; O'Neill, Marie S; Gronlund, Carina J; Catalano, Linda; Conlon, Kathryn C; Parker, Edith A

    2014-02-01

    Extreme heat events (EHEs) are becoming more intense, more frequent and longer lasting in the 21st century. These events can disproportionately impact the health of low-income, minority, and urban populations. To better understand heat-related intervention strategies used by four U.S. cities, we conducted 73 semi-structured interviews with government and non-governmental organization leaders representing public health, general social services, emergency management, meteorology, and the environmental planning sectors in Detroit, MI; New York City, NY; Philadelphia, PA and Phoenix, AZ-cities selected for their diverse demographics, climates, and climate adaptation strategies. We identified activities these leaders used to reduce the harmful effects of heat for residents in their city, as well as the obstacles they faced and the approaches they used to evaluate these efforts. Local leaders provided a description of how local context (e.g., climate, governance and city structure) impacted heat preparedness. Despite the differences among study cities, political will and resource access were critical to driving heat-health related programming. Upon completion of our interviews, we convened leaders in each city to discuss these findings and their ongoing efforts through day-long workshops. Our findings and the recommendations that emerged from these workshops could inform other local or national efforts towards preventing heat-related morbidity and mortality. PMID:24531122

  3. Histone chaperone Anp32e removes H2A.Z from DNA double-strand breaks and promotes nucleosome reorganization and DNA repair

    PubMed Central

    Gursoy-Yuzugullu, Ozge; Ayrapetov, Marina K.; Price, Brendan D.

    2015-01-01

    The repair of DNA double-strand breaks (DSBs) requires open, flexible chromatin domains. The NuA4Tip60 complex creates these flexible chromatin structures by exchanging histone H2A.Z onto nucleosomes and promoting acetylation of histone H4. Here, we demonstrate that the accumulation of H2A.Z on nucleosomes at DSBs is transient, and that rapid eviction of H2A.Z is required for DSB repair. Anp32e, an H2A.Z chaperone that interacts with the C-terminal docking domain of H2A.Z, is rapidly recruited to DSBs. Anp32e functions to remove H2A.Z from nucleosomes, so that H2A.Z levels return to basal within 10 min of DNA damage. Further, H2A.Z removal by Anp32e disrupts inhibitory interactions between the histone H4 tail and the nucleosome surface, facilitating increased acetylation of histone H4 following DNA damage. When H2A.Z removal by Anp32e is blocked, nucleosomes at DSBs retain elevated levels of H2A.Z, and assume a more stable, hypoacetylated conformation. Further, loss of Anp32e leads to increased CtIP-dependent end resection, accumulation of single-stranded DNA, and an increase in repair by the alternative nonhomologous end joining pathway. Exchange of H2A.Z onto the chromatin and subsequent rapid removal by Anp32e are therefore critical for creating open, acetylated nucleosome structures and for controlling end resection by CtIP. Dynamic modulation of H2A.Z exchange and removal by Anp32e reveals the importance of the nucleosome surface and nucleosome dynamics in processing the damaged chromatin template during DSB repair. PMID:26034280

  4. Comparison of Microstructure and Mechanical Properties of AZ91D Alloy Formed by Rheomolding and High-Pressure Die Casting

    NASA Astrophysics Data System (ADS)

    Qi, M. F.; Kang, Y. L.; Yan, Y.; Zhu, G. M.; Liao, W. N.

    2015-10-01

    The microstructure and mechanical properties of AZ91D alloy thin-wall parts produced by the rheomolding (RM) process were investigated and compared with the same alloy formed by conventional high-pressure die casting (HPDC). The results indicate that the RM process is able to get such AZ91D parts in which ? 1 -Mg with average size of 27.36 ?m are spherical and uniformly distributed in the matrix, and the matrix is a mixture of numerous fine ? 2 -Mg and intermetallic ?-Mg17Al12. High mechanical properties including ultimate tensile strength (UTS) of 270 MPa, yield strength (YS) of 169 MPa, elongation of 7.1%, and Vickers hardness of 102 are obtained in parts formed by RM due to the fine and uniform microstructure and less porosities. Compared with HPDC, the UTS, YS, elongation, and hardness of RM AZ91D are increased by 14.4, 9.7, 86.8, and 21.4%, respectively. The solidified grains in RM AZ91D alloy show a smaller aluminum gradient than that in HPDC. This indicates that the solidification of the RM AZ91D is closer to equilibrium.

  5. Identification and characterization of the two isoforms of the vertebrate H2A.Z histone variant.

    PubMed

    Matsuda, Ryo; Hori, Tetsuya; Kitamura, Hiroshi; Takeuchi, Kozo; Fukagawa, Tatsuo; Harata, Masahiko

    2010-07-01

    Histone variants play important roles in the epigenetic regulation of genome function. The histone variant H2A.Z is evolutionarily conserved from yeast to vertebrates, and it has been reported to have multiple effects upon gene expression and insulation, and chromosome segregation. Recently two genes encoding H2A.Z were identified in the vertebrate genome. However, it is not yet clear whether the proteins transcribed from these genes are functionally distinct. To address this issue, we knocked out each gene individually in chicken DT40 cells. We found that two distinct proteins, H2A.Z-1 and H2A.Z-2, were produced from these genes, and that these proteins could be separated on a long SDS-PAGE gel. The two isoforms were deposited to a similar extent by the SRCAP chromatin-remodeling complex, suggesting redundancy to their function. However, cells lacking either one of the two isoforms exhibited distinct alterations in cell growth and gene expression, suggesting that the two isoforms have differential effects upon nucleosome stability and chromatin structure. These findings provide insight into the molecular basis of the multiple functions of the H2A.Z gene products. PMID:20299344

  6. Combined effect of pulse electron beam treatment and thin hydroxyapatite film on mechanical features of biodegradable AZ31 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Surmeneva, M. A.; Tyurin, A. I.; Teresov, A. D.; Koval, N. N.; Pirozhkova, T. S.; Shuvarin, I. A.; Surmenev, R. A.

    2015-11-01

    The morphology, elemental, phase composition, nanohardness, and Young's modulus of the hydroxyapatite (HA) coating deposited via radio frequency (RF) magnetron sputtering onto the AZ31 surface were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and nanoindentationtechniques. The calcium phosphate (Ca/P) molar ratio of the HA coating deposited via RF-magnetron sputtering onto AZ31 substrates according to EDX was 1.57+0.03. The SEM experiments revealed significant differences in the morphology of the HA film deposited on untreated and treated with the pulsed electron beam (PEB) AZ31 substrate. Nanoindentation studies demonstrated significant differences in the mechanical responses of the HA film deposited on the initial and PEB-modified AZ31 substrates. The nanoindentation hardness and the Young's modulus of the HA film on the magnesium alloy modified using the PEB treatment were higher than that of the HA layer on the untreated substrate. Moreover, the HA film fabricated onto the PEB-treated surface was more resistant to plastic deformation than the same film on the untreated AZ31 surface.

  7. Dynamic Changes in Occupancy of Histone Variant H2A.Z during Induced Somatic Cell Reprogramming.

    PubMed

    Dong, Fulu; Song, Zhenwei; Yu, Jiali; Zhang, Baole; Jiang, BaoChun; Shen, Ying; Lu, Youde; Song, Chunlei; Cong, Peiqing; Liu, Honglin

    2016-01-01

    The development of induced pluripotent stem cells (iPSCs) has enabled study of the mechanisms underlying cellular reprogramming. Here, we have studied the dynamic distribution of H2A.Z during induced reprogramming with chromatin immunoprecipitation deep sequencing (ChIP-Seq). We found that H2A.Z tended to accumulate around transcription start site (TSS) and incorporate in genes with a high transcriptional activity. GO analysis with H2A.Z incorporated genes indicated that most genes are involved in chromatin assembly or disassembly and chromatin modification both in MEF and Day 7 samples, not in iPSCs. Furthermore, we detected the highest level of incorporation of H2A.Z around TSS in Day 7 samples compared to MEFs and iPSCs. GO analysis with only incorporated genes in Day 7 also displayed the function of chromatin remodeling. So, we speculate H2A.Z may be responsible for chromatin remodeling to enhance the access of transcription factors to genes important for pluripotency. This study therefore provides a deeper understanding of the mechanisms underlying induced reprogramming. PMID:26783401

  8. Effects of Yttrium Addition on Microstructure and Mechanical Properties of AZ80-2Sn Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Xue, Hansong; Yang, Gang; Li, Di; Xing, Zhihui; Pan, Fusheng

    2015-12-01

    The effects of Y on microstructure and mechanical properties of as-cast AZ80-2Sn magnesium alloys were investigated by optical microscopy, scanning electron microscopy and X-ray diffraction. Y addition not only changes the as-cast microstructure but also influences the mechanical properties of AZ80-2Sn alloy. Unmodified AZ80-2Sn alloys under casting state show that Mg17Al12 eutectic phase is semicontinuous and reticulated shape and distributes mainly at grain boundaries. Moreover, there are numerous Mg2Sn precipitate particles dispersing in Mg17Al12 eutectic phases. Y addition to as-cast AZ80-2Sn alloys has an important influence on the precipitation phase. But there has no obvious effect on grain refinement with Y addition. The results show that the AZ80-2Sn alloys with variable Y contents all contain Al2Y phase. By adding Y, the amount of Mg17Al12 is decreased and the dimension of that is reduced. Mg17Al12 eutectic phase turns to discontinuous, and the more disperse phases occur with the increase of Y content. The tensile tests indicate that a minor addition of Y can contribute to the formation of the dispersed small polygonal Al2Y particles and the improvement in the room-temperature strength. However, excessive Y addition leads to the coarsening of Al2Y phases, and thus results in the decline of strength and ductility.

  9. Dynamic Changes in Occupancy of Histone Variant H2A.Z during Induced Somatic Cell Reprogramming

    PubMed Central

    Dong, Fulu; Song, Zhenwei; Yu, Jiali; Zhang, Baole; Jiang, BaoChun; Shen, Ying; Lu, Youde; Song, Chunlei; Cong, Peiqing; Liu, Honglin

    2016-01-01

    The development of induced pluripotent stem cells (iPSCs) has enabled study of the mechanisms underlying cellular reprogramming. Here, we have studied the dynamic distribution of H2A.Z during induced reprogramming with chromatin immunoprecipitation deep sequencing (ChIP-Seq). We found that H2A.Z tended to accumulate around transcription start site (TSS) and incorporate in genes with a high transcriptional activity. GO analysis with H2A.Z incorporated genes indicated that most genes are involved in chromatin assembly or disassembly and chromatin modification both in MEF and Day 7 samples, not in iPSCs. Furthermore, we detected the highest level of incorporation of H2A.Z around TSS in Day 7 samples compared to MEFs and iPSCs. GO analysis with only incorporated genes in Day 7 also displayed the function of chromatin remodeling. So, we speculate H2A.Z may be responsible for chromatin remodeling to enhance the access of transcription factors to genes important for pluripotency. This study therefore provides a deeper understanding of the mechanisms underlying induced reprogramming. PMID:26783401

  10. Mexico City Aerosol Transect

    NASA Astrophysics Data System (ADS)

    Lewandowski, P. A.; Eichinger, W. E.; Prueger, J.; Holder, H. L.

    2007-12-01

    A radiative impact study was conducted in Mexico City during MILAGRO/MIRAGE campaign in March of 2006. On a day when the predominant wind was from the north to the south, authors measured radiative properties of the atmosphere in six locations across the city ranging from the city center, through the city south limits and the pass leading out of the city (causing pollutants to funnel through the area). A large change in aerosol optical properties has been noticed. The aerosol optical depth has generally increased outside of the city and angstrom coefficient has changed significantly towards smaller values. Aerosol size distribution was calculated using SkyRadPack. The total optical depths allowed coincidental lidar data to calculate total extinction profiles for all the locations for 1064nm.

  11. Texture Development in a Friction Stir Lap-Welded AZ31B Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Naik, B. S.; Chen, D. L.; Cao, X.; Wanjara, P.

    2014-09-01

    The present study was aimed at characterizing the microstructure, texture, hardness, and tensile properties of an AZ31B-H24 Mg alloy that was friction stir lap welded (FSLWed) at varying tool rotational rates and welding speeds. Friction stir lap welding (FSLW) resulted in the presence of recrystallized grains and an associated hardness drop in the stir zone (SZ). Microstructural investigation showed that both the AZ31B-H24 Mg base metal (BM) and SZ contained ?-Mg17Al12 and Al8Mn5 second phase particles. The AZ31B-H24 BM contained a type of basal texture (0001)<110> with the (0001) plane nearly parallel to the rolled sheet surface and <110> directions aligned in the rolling direction. FSLW resulted in the formation of another type of basal texture (0001)<100> in the SZ, where the basal planes (0001) became slightly tilted toward the transverse direction, and the prismatic planes (100) and pyramidal planes (101) exhibited a 30 deg + ( n - 1) 60 deg rotation ( n = 1, 2, 3, ) with respect to the rolled sheet normal direction, due to the shear plastic flow near the pin surface that occurred from the intense local stirring. With increasing tool rotational rate and decreasing welding speed, the maximum intensity of the basal poles (0001) in the SZ decreased due to a higher degree of dynamic recrystallization that led to a weaker or more random texture. The tool rotational rate and welding speed had a strong effect on the failure load of FSLWed joints. A combination of relatively high welding speed (20 mm/s) and low tool rotational rate (1000 rpm) was observed to be capable of achieving a high failure load. This was attributed to the relatively small recrystallized grains and high intensity of the basal poles in the SZ arising from the low heat input as well as the presence of a small hooking defect.

  12. Ultrasonic Examination of Double-Shell Tank 241-AZ-101. Examination Completed July 2007.

    SciTech Connect

    Pardini, Allan F.; Weier, Dennis R.

    2007-08-12

    AREVA NC Inc. (AREVA), under a contract from CH2M Hill Hanford Group (CH2M Hill), has performed an ultrasonic examination of selected portions of Double-Shell Tank 241-AZ-101. PNNL is responsible for preparing a report(s) that describes the results of the AREVA ultrasonic examinations. The purpose of this examination was to provide information that could be used to evaluate the integrity of the wall of the primary tank. The requirements for the ultrasonic examination of Tank 241-AZ-101 were to detect, characterize (identify, size, and locate), and record measurements made of any wall thinning, pitting, or cracks that might be present in the wall of the primary tank. Any measurements that exceed the requirements set forth in the Engineering Task Plan (ETP), RPP-Plan-27202 (Jensen 2005) and summarized on page 1 of this document, are to be reported to CH2M HILL and the Pacific Northwest National Laboratory (PNNL) for further evaluation. Under the contract with CH2M HILL, all data is to be recorded on electronic media and paper copies of all measurements are provided to PNNL for third-party evaluation. PNNL is responsible for preparing a report(s) that describes the results of the AREVA ultrasonic examinations. The results of the examination of Tank 241-AZ-101 have been evaluated by PNNL personnel. The ultrasonic examination consisted of two vertical 15-in.-wide scan paths over the entire height of the tank and the heat-affected zone (HAZ) of five vertical welds and one horizontal weld from Riser 89. The examination also included two vertical 15-in.-wide scan paths over the entire height of the tank from Riser 90. The examination was performed to detect any wall thinning, pitting, or cracking in the primary tank wall.

  13. Low-Cycle Fatigue Behavior of Die-Cast Mg Alloys AZ91 and AM60

    NASA Astrophysics Data System (ADS)

    Rettberg, Luke H.; Jordon, J. Brian; Horstemeyer, Mark F.; Jones, J. Wayne

    2012-07-01

    The influence of microstructure and artificial aging response (T6) on the low-cycle fatigue behavior of super vacuum die-cast (SVDC) AZ91 and AM60 has been investigated. Fatigue lifetimes were determined from the total strain-controlled fatigue tests for strain amplitudes of 0.2 pct, 0.4 pct, 0.6 pct, 0.8 pct, and 1.0 pct under fully reversed loading at a frequency of 5 Hz. Cyclic stress-strain behavior was determined using an incremental step test (IST) and compared with the more traditional constant amplitude test. Two locations in a prototype casting were investigated to examine the role of microstructure and porosity on fatigue behavior. At all total strain amplitudes microstructure refinement had a negligible impact on fatigue life because of significant levels of porosity. AM60 showed an improvement in fatigue life at higher strain amplitudes when compared with AZ91 because of higher ductility. T6 heat treatment had no impact on fatigue life. Cyclic stress-strain behavior obtained via the incremental step test varied from constant amplitude test results due to load history effects. The constant amplitude test is believed to be the more accurate test method. In general, larger initiation pores led to shorter fatigue life. The fatigue life of AZ91 was more sensitive to initiation pore size and pore location than AM60 at the lowest tested strain amplitude of 0.2 pct. Fatigue crack paths did not favor any specific phase, interdentritic structure or eutectic structure. A multistage fatigue (MSF) model showed good correlation to the experimental strain-life results. The MSF model reinforced the dominant role of inclusion (pore) size on the scatter in fatigue life.

  14. Exotic decays of a heavy neutral Higgs through HZ/AZ channel

    NASA Astrophysics Data System (ADS)

    Coleppa, Baradhwaj; Kling, Felix; Su, Shufang

    2014-09-01

    Models of electroweak symmetry breaking with extended Higgs sectors are theoretically well motivated. In this study, we focus on the Two Higgs Doublet Model with a low energy spectrum containing scalars H and a pseudoscalar A. We study the decays A ? HZ or H ? AZ, which could reach sizable branching fractions in certain parameter regions. With detailed collider analysis, we obtain model independent exclusion bounds as well as discovery reach at the 14 TeV LHC for the process: gg ? A/ H ? HZ/ AZ, looking at final states bb??, ???? and ZZZ(4 ? + 2 j) for ? = e, ?. We further interpret these bounds in the context of the Type II Two Higgs Doublet Model, considering three different classes of processes: A ? h 0 Z, A ? H 0 Z, and H 0 ? AZ, in which h 0 and H 0 are the light and heavy CP-even Higgses respectively. For 100 fb-1 integrated luminosity at the 14 TeV LHC, we find that for parent particle mass around 300-400 GeV, A ? h 0 Z has the greatest reach when H 0 is interpreted as the 126 GeV Higgs: most regions in the tan ? versus sin( ? - ?) plane can be excluded and a significant fraction at small and large tan ? can be covered by discovery. For 126 GeV h 0, only relatively small tan ? ? 10 (5) can be reached by exclusion (discovery) while a wide range of sin( ? - ?) is accessible. For A ? H 0 Z, the reach is typically restricted to sin( ? - ?) ~ 1 with tan ? ? 10 in bb?? and ???? channels. The ZZZ(4 ?2 j) channel, on the other hand, covers a wide range of 0 .3 < | sin( ? - ?)| < 1 for tan ? ? 4. H 0 ? AZ typically favors negative values of sin( ? - ?), with exclusion/discovery reach possibly extending to all values of tan ?. A study of exotic decays of extra Higgses appearing in extensions of the Standard Model would extend the reach at the LHC and provides nice complementarity to conventional Higgs search channels.

  15. Effects of Processing Parameters on Thixoformability and Defects of AZ91D

    NASA Astrophysics Data System (ADS)

    Li, Yuandong; Ma, Ying; Chen, Tijun; Xu, Weijun; Gao, Wei

    The thixoformability and defect formation of AZ91D magnesium alloy are studied with different processing parameters including reheating temperature, time and die temperature. The results indicated that the suitable processing parameters should be reheating temperature between 575-595C, reheating time more than 75 min, and die temperature over 275C. Four types of defects, coldshut, liquid segregation, microporosity and cracks, have been observed in the thixoformed products if the processing parameters are not controlled properly. Among these defects, microporosity and cracks are always dominant.

  16. Transmission electron microscopy investigations of AZ91 alloy deformed by equal-channel angular pressing.

    PubMed

    Braszczy?ska-Malik, K N; Lity?ska, L; Baliga, W

    2006-10-01

    The microstructure of transverse and longitudinal sections of a commercial AZ91 alloy processed by equal-channel angular pressing was examined by transmission electron microscopy. A high dislocation density and large number of deformation twins were observed in the investigated material. The {102}(matrix) // {012}(twin) twinning system was determined by selection area diffraction patterns obtained from the twin and matrix. Transmission electron microscopy analyses also revealed that the twins interacted with each other and pile-ups of dislocations occurred near the twin boundary. PMID:17100895

  17. Grain Boundary Wetting and Solidification of Constitutional Liquid in AZ91 MG Cast Alloy

    NASA Astrophysics Data System (ADS)

    Zhu, Tianping; Chen, Zhan W.; Gao, Wei

    In this study, constitutional liquation in AZ91 cast alloy at 440C and 465C was experimentally simulated. Metallurgical examination was conducted to reveal the morphology of the constitutional liquid and dihedral angle was measured to evaluate the wettability of the liquid on grain boundary. Dihedral angle was found to be initially ~30 degree and thus grain boundaries were incomplete wet. During annealing, the metastable constitutional liquid resolidified, followed by grain growth. The extent of grain boundary wetting by the remaining liquid increased slightly with treating time. The rate of resolidification was also evaluated and the factors affecting this rate were discussed.

  18. Advances in magnesium alloys and composites; Proceedings of the Symposium, Phoenix, AZ, Jan. 26, 1988

    SciTech Connect

    Paris, H.G.; Hunt, W.H.

    1988-01-01

    The present conference discusses the development history of Mg's structural applications, a comparison of the properties of two-phase HCP+BCC and single-phase BCC Mg-Li alloys, the room temperature creep of die-cast AZ91 Mg alloy at low stress, and the relationship between the microstructural properties and corrosion behavior of Mg alloy ingots and castings. Also discussed are the characteristics of rapidly solidified Mg alloys containing rare earth additions, the role of rapid solidification processing on Mg alloys' microstructure and properties, the effects of alloying elements on the corrosion resistance of rapidly solidified Mg alloys, and alloying effects in graphite-reinforced/Mg-matrix composites.

  19. Low temperature superplasticity in an AZ91 magnesium alloy processed by ECAE

    SciTech Connect

    Mabuchi, M.; Iwasaki, H.; Yanase, K.; Higashi, K.

    1997-03-15

    Magnesium alloys are especially suitable for use of the structural components in aerospace and outerspace applications due to their low density. In general, however, magnesium alloys have poor workability because of their h.c.p. structure. Therefore it is desirable to improve the poor workability, and superplastic forming is expected to be put into the processing in practical applications. In the present work, equal channel angular extrusion (ECAE), which allows one to attain high shear strain, has been conducted on an AZ91 magnesium alloy. The alloy processed by ECAE exhibited superplastic behavior at low temperatures of 448 and 473 K, which are about 0.5T{sub m}.

  20. Evaluation of 241-AZ tank farm supporting phase 1 privatization waste feed delivery

    SciTech Connect

    CARLSON, A.B.

    1998-11-19

    This evaluation is one in a series of evaluations determining the process needs and assessing the adequacy of existing and planned equipment in meeting those needs at various double-shell tank farms in support of Phase 1 privatization. A number of tank-to-tank transfers and waste preparation activities are needed to process and feed waste to the private contractor in support of Phase 1 privatization. The scope of this evaluation is limited to process needs associated with 241-AZ tank farm during the Phase 1 privatization.

  1. Thin hydroxyapatite coating on AZ91D magnesium alloy fabricated via RF-magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Mukhametkaliyev, T. M.; Surmeneva, M. A.; Mueller, M.; Prymak, O.; Epple, M.; Surmenev, R. A.

    2015-11-01

    In this study the morphology, composition, structure and wettability of radiofrequency (RF) magnetron sputter-deposited hydroxyapatite (HA) coating deposited on the surface of AZ91D magnesium alloy were investigated. The results revealed that the fabricated coating is uniform, homogeneous with the structure of the stoichiometric HA. The deposition of the HA coating did not change significantly the surface wettability of the bare alloy, however water contact angle dynamics in the case of the HA coated substrates revealed a lower rate of a droplet spreading over the surface.

  2. Interfacial characteristics of squeeze-cast SiC reinforced AZ91D magnesium-based composites

    SciTech Connect

    Lo, J.; Carpenter, G.J.C.; Charest, M.

    1996-10-01

    The method of producing magnesium-based composites with silicon carbide (SiC) particulates embedded in the matrix of magnesium AZ91D alloy by the squeeze-casting technique are described. This method involves the fabrication of a SiC particulate preform and the subsequent squeezing of molten magnesium into the preform. In this study, alumina, aluminum phosphate and a proprietary binder were used for the fabrication of SiC particulate preforms. The procedures employed in the fabrication of SiC/AZ91D composites are presented, together with the results of characterization of the composites using optical and transmission electron microscopy. Special attention is given to the reaction products in the bulk alloy and at the interfaces between SiC particles and the AZ91D matrix alloy.

  3. In vitro corrosion of pure magnesium and AZ91 alloy—the influence of thin electrolyte layer thickness

    PubMed Central

    Zeng, Rong-Chang; Qi, Wei-Chen; Zhang, Fen; Li, Shuo-Qi

    2016-01-01

    In vivo degradation predication faces a huge challenge via in vitro corrosion test due to the difficulty for mimicking the complicated microenvironment with various influencing factors. A thin electrolyte layer (TEL) cell for in vitro corrosion of pure magnesium and AZ91 alloy was presented to stimulate the in vivo corrosion in the micro-environment built by the interface of the implant and its neighboring tissue. The results demonstrated that the in vivo corrosion of pure Mg and the AZ91 alloy was suppressed under TEL condition. The AZ91 alloy was more sensitive than pure Mg to the inhibition of corrosion under a TEL thickness of less than 200 µm. The TEL thickness limited the distribution of current, and thus localized corrosion was more preferred to occur under TEL condition than in bulk solution. The TEL cell might be an appropriate approach to simulating the in vivo degradation of magnesium and its alloys. PMID:26816655

  4. In vitro corrosion of pure magnesium and AZ91 alloy-the influence of thin electrolyte layer thickness.

    PubMed

    Zeng, Rong-Chang; Qi, Wei-Chen; Zhang, Fen; Li, Shuo-Qi

    2016-03-01

    In vivo degradation predication faces a huge challenge via in vitro corrosion test due to the difficulty for mimicking the complicated microenvironment with various influencing factors. A thin electrolyte layer (TEL) cell for in vitro corrosion of pure magnesium and AZ91 alloy was presented to stimulate the in vivo corrosion in the micro-environment built by the interface of the implant and its neighboring tissue. The results demonstrated that the in vivo corrosion of pure Mg and the AZ91 alloy was suppressed under TEL condition. The AZ91 alloy was more sensitive than pure Mg to the inhibition of corrosion under a TEL thickness of less than 200 µm. The TEL thickness limited the distribution of current, and thus localized corrosion was more preferred to occur under TEL condition than in bulk solution. The TEL cell might be an appropriate approach to simulating the in vivo degradation of magnesium and its alloys. PMID:26816655

  5. Evaluating the effect of land-use and land-cover change on climate in the greater Phoenix, AZ, region

    NASA Astrophysics Data System (ADS)

    Georgescu, Matei

    The effect of land-use/land-cover change (LULCC) on the summer climate of one of the nation's most rapidly expanding metropolitan complexes, the Greater Phoenix, AZ, region, is investigated. The initial part of this study evaluates the first-order effect of LULCC over Greater Phoenix using high-resolution (2-km grid spacing) Regional Atmospheric Modeling System (RAMS) simulations of three "wet" and three "dry" summer seasons. Experiments were carried out with two different landscape reconstructions for the region: a circa-1992 representation based on satellite observations and a hypothetical "pre-settlement" scenario where the anthropogenic landscape of irrigated agriculture and urban pixels was replaced with current semi-natural vegetation. The main findings are: (1) The presence of extensive irrigated agriculture adjacent to the urban area dampens the regional-mean warming due to urbanization. (2) The imposed LULCC produces a systematic increase in precipitation to the north and east of the city during dry summers. Guided by these findings, the impact of the actual landscape evolution, using LULC reconstructions based on circa-1973, circa-1992, and circa-2001 satellite data, on the Greater Phoenix regional climate was examined, and the relevant atmospheric dynamical processes investigated. The main findings are: (1) From 1973 to 2001, areal coverage of irrigated agriculture declined and that of urban areas increased, resulting in significantly greater simulated regional-mean temperatures for the 2001 than for the 1973 LULC. (2) As with the 1992 to pre-settlement comparison, precipitation is enhanced for the 2001 compared to the 1973 landscape during dry summers. In addition, rainfall enhancement relative to the 1973 LULC is increased for 2001 relative to the 1992 LULC. (3) Heterogeneity in the surface fluxes produces preferentially located mesoscale circulations on most days that are stronger for the 2001 compared to the 1973 LULC, due to the increased planetary boundary layer (PBL) heating via enhanced turbulent heat flux. (4) The effect of these stronger circulations is to warm and dry the lower part of the PBL and moisten the upper part of the PBL for 2001 relative to 1973. (5) The precise physical pathway(s) whereby precipitation enhancement occurs with evolving landscape reveals a complicated interplay among scales that warrants future research.

  6. Utah: Salt Lake City

    Atmospheric Science Data Center

    2014-05-15

    article title: Snow-Covered Peaks of the Wasatch and Uinta Mountains ... backdrops for the 2002 Winter Olympics, to be held in Salt Lake City, Utah. The mountains surrounding Salt Lake City are renowned for the dry, powdery snow that results from the arid climate and location at the western edge of the ...

  7. Walkout in Crystal City

    ERIC Educational Resources Information Center

    Barrios, Greg

    2009-01-01

    When students take action, they create change that extends far beyond the classroom. In this article, the author, who was a former teacher from Crystal City, Texas, remembers the student walkout that helped launch the Latino civil rights movement 40 years ago. The Crystal City student walkout remains a high point in the history of student activism

  8. Innovation and the City

    ERIC Educational Resources Information Center

    Kleiman, Neil; Forman, Adam; Ko, Jae; Giles, David; Bowles, Jonathan

    2013-01-01

    With Washington trapped in budget battles and partisan gridlock, cities have emerged as the best source of government innovation. Nowhere is this more visible than in New York City. Since taking office in 2002, Mayor Bloomberg has introduced a steady stream of innovative policies, from a competition to recruit a new applied sciences campus and a…

  9. The Plains City Story

    ERIC Educational Resources Information Center

    van Olphen, Marcela; Rios, Francisco; Berube, William; Dexter, Robin; McCarthy, Robert

    2006-01-01

    This case study portrays a contemporary phenomenon that affects many U.S. school districts. Specifically, the authors address the challenges that the superintendent of the Plains City school district faced as a result of a change in the demographic distribution of his district. The gradual development of the pig farming industry in Plains City

  10. The Industrial City

    ERIC Educational Resources Information Center

    Mohl, Raymond

    1976-01-01

    This article, the sixth installment in Environment's "Looking Back" series, traces the woes of America's industrialized cities to the movement that developed cities primarily as centers for industrial enterprise rather than as places for people to live. Today's social ills, from pollution to poverty, developed from that movement. (BT)

  11. Salt Lake City, Utah

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Salt Lake City, Utah, will host the 2002 Winter Olympic Games. The city is located on the southeastern shore of the Great Salt Lake and sits to the west of the Wasatch Mountains, which rise more than 3,500 meters (10,000 feet) above sea level. The city was first settled in 1847 by pioneers seeking relief from religious persecution. Today Salt Lake City, the capital of Utah, is home to more than 170,000 residents. This true-color image of Salt Lake City was acquired by the Enhanced Thematic Mapper Plus (ETM+), flying aboard Landsat 7, on May 26, 2000. The southeastern tip of the Great Salt Lake is visible in the upper left of the image. The furrowed green and brown landscape running north-south is a portion of the Wasatch Mountains, some of which are snow-capped (white pixels). The greyish pixels in the center of the image show the developed areas of the city. A number of water reservoirs can be seen east of the mountain range. Salt Lake City International Airport is visible on the northwestern edge of the city. About 20 miles south of the airport is the Bingham Canyon Copper Mine (tan pixels), the world's largest open pit excavation. See also this MODIS image of Utah. Image courtesy NASA Landsat7 Science Team and USGS Eros Data Center

  12. Walkout in Crystal City

    ERIC Educational Resources Information Center

    Barrios, Greg

    2009-01-01

    When students take action, they create change that extends far beyond the classroom. In this article, the author, who was a former teacher from Crystal City, Texas, remembers the student walkout that helped launch the Latino civil rights movement 40 years ago. The Crystal City student walkout remains a high point in the history of student activism…

  13. A Feasiblity Study on Spot Friction Welding of Magnesium Alloy AZ31

    SciTech Connect

    Santella, Michael L; Pan, Dr. Tsung-Yu; Frederick, David Alan; Schwartz, William

    2007-01-01

    Spot friction welding (SFW) is a novel variant of the linear friction stir welding process with the potential to create strong joints between similar, as well as dissimilar sheet metals. It is particularly suitable for soft, low melting point metals such as aluminum, magnesium, and their alloys where resistance spot welding can cause defects such as voids, trapped gas and micro-cracks due to the intense heat requirement for joint formation. Up to now, spot friction welding has focused primarily on aluminum alloys. This paper presents a feasibility study on spot friction welding of AZ31, a wrought magnesium alloy available in sheet form. Lap joints of 1.58-mm-thick magnesium alloy AZ31B-O sheet were produced by spot friction welding. The spot welds were made in 2 sec with 15-mm-diameter pin tool rotating at 500-2,000 rpm. The tool was inserted into 2-sheet stack-ups to depths of either 2.4 or 2.8 mm relative to the top sheet surface. Tensile-shear testing showed that joint strengths up to 4.75 kN were obtained. The removal of surface oxides from the sheets prior to welding increased lap shear strengths about 50% at the 2.4-mm insertion depth and it promoted failure by nugget pull-out rather than by interface separation.

  14. Characterization of fold defects in AZ91D and AE42 magnesium alloy permanent mold castings

    SciTech Connect

    Bichler, L.; Ravindran, C.

    2010-03-15

    Casting premium-quality magnesium alloy components for aerospace and automotive applications poses unique challenges. Magnesium alloys are known to freeze rapidly prior to filling a casting cavity, resulting in misruns and cold shuts. In addition, melt oxidation, solute segregation and turbulent metal flow during casting contribute to the formation of fold defects. In this research, formation of fold defects in AZ91D and AE42 magnesium alloys cast via the permanent mold casting process was investigated. Computer simulations of the casting process predicted the development of a turbulent metal flow in a critical casting region with abrupt geometrical transitions. SEM and light optical microscopy examinations revealed the presence of folds in this region for both alloys. However, each alloy exhibited a unique mechanism responsible for fold formation. In the AZ91D alloy, melt oxidation and velocity gradients in the critical casting region prevented fusion of merging metal front streams. In the AE42 alloy, limited solubility of rare-earth intermetallic compounds in the {alpha}-Mg phase resulted in segregation of Al{sub 2}RE particles at the leading edge of a metal front and created microstructural inhomogeneity across the fold.

  15. Research on microstructures of sub-rapidly solidified AZ61 Magnesium Alloy

    SciTech Connect

    Teng Haitao; Zhang Xiaoli; Zhang Zhongtao; Li Tingju; Cockcroft, Steve

    2009-06-15

    AZ61 magnesium alloy foils of 0.5-3.0 mm thick were successfully produced by using sub-rapid solidification technique. Microstructures of conventionally solidified (CS) and sub-rapidly solidified (sub-RS) alloys were examined by optical microscope (OM) and scanning electron microscope (SEM). The results showed that the cellular grain of 1.8-13.5 {mu}m can be obtained during sub-rapid solidification process. Phase compositions and microdistribution of the alloying elements in the foils were analyzed by X-ray diffraction (XRD) and electron probe microanalyzer (EPMA), respectively. The eutectic transformation L {yields} {alpha}-Mg + {beta}-Mg{sub 17}Al{sub 12} and microsegregation in conventionally solidified AZ61 alloy were remarkably suppressed in sub-rapid solidification process. As a consequence, the alloying elements Al, Zn, Mn showed much higher solid solubility and the sub-rapid solidification microstructures dominantly consisted of supersaturated {alpha}-Mg solid solution. Meanwhile, the {beta}-Mg{sub 17}Al{sub 12} phases located in the {alpha}-Mg grain boundaries are largely decreased due to high solidification cooling rate.

  16. Thermal Microstructural Stability of AZ31 Magnesium after Severe Plastic Deformation

    SciTech Connect

    Young, John P.; Askari, Hesam A.; Hovanski, Yuri; Heiden, Michael J.; Field, David P.

    2015-03-01

    Both equal channel angular pressing and friction stir processing have the ability to refine the grain size of twin roll cast AZ31 magnesium and potentially improve its superplastic properties. This work used isochronal and isothermal heat treatments to investigate the microstructural stability of twin roll cast, equal channel angular pressed and friction stir processed AZ31 magnesium. For both heat treatment conditions, it was found that the twin roll casted and equal channel angular pressed materials were more stable than the friction stir processed material. Calculations of the grain growth kinetics showed that severe plastic deformation processing decreased the activation energy for grain boundary motion with the equal channel angular pressed material having the greatest Q value of the severely plastically deformed materials and that increasing the tool travel speed of the friction stir processed material improved microstructural stability. The Hollomon-Jaffe parameter was found to be an accurate means of identifying the annealing conditions that will result in substantial grain growth and loss of potential superplastic properties in the severely plastically deformed materials. In addition, Humphreys’s model of cellular microstructural stability accurately predicted the relative microstructural stability of the severely plastically deformed materials and with some modification, closely predicted the maximum grain size ratio achieved by the severely plastically deformed materials.

  17. CHARACTERIZATION AND FORMABILITY OF CONTINUOUS-CAST AZ31B MAGNESIUM ALLOY SHEETS

    SciTech Connect

    Rohatgi, Aashish; Herling, Darrell R.; Nyberg, Eric A.

    2009-09-24

    The goal of this work is to understand the inter-relationship between the initial properties of continuous-cast magnesium alloy (AZ31B) sheets and their subsequent formability and post-formed mechanical performance for use in cost-effective, lightweight, automotive body panels. As-received sheets, provided by the Automotive Metals Division (AMD-602) team, were characterized by surface roughness measurements using mechanical profilometry. The arithmetic mean deviation of profile (Ra) and the maximum two-point height of profile (Ry) of the as-received sheets ranged from ~0.2-2 ?m and ~2-15 ?m, respectively. Several commercial lubricants were evaluated by thermal analysis and the liquid phase of the lubricants was found to evaporate/decompose upon heating leaving behind a solid residue upon heating to temperatures exceeding ~125-150C. Elevated temperature bending-under-tension (BUT) friction tests were conducted at 350C and the coefficient-of-friction values ranged from a minimum of ~0.1 (for tungsten disulfide lubricant) to ~0.7 when no lubricant was used. These results, in conjunction with those from the forming trials conducted by the AMD-602 team, will be eventually used to determine the role of sheet-die friction in determining the formability of AZ31B sheets.

  18. Identification of an advanced constitutive model of Magnesium alloy AZ31B

    NASA Astrophysics Data System (ADS)

    Liu, Z. G.; Massoni, E.

    2011-05-01

    The main aim of this paper is to study the flow behavior of the AZ31B magnesium alloy by means of tensile tests performed in extended ranges of temperature and strain rates. The flow stress-strain curves analyzed by power law type constitutive equation [1] can only fit well with experimental curves at the work-hardening stage. A new mathematical model is studied to describe the softening behavior of material based on tensile experiments. The relative parameters are obtained by fitting the equation with the experimental data. The genetic algorithm has been used to obtain the global optimal fitting parameters. The comparison between the fitted and experimental data proves the effectiveness of the model. The results indicate that this model leads to a better simulation of the flow stress during the softening stage than that of the power law equation. Based on this model, the deep drawing process has been simulated with the commercial finite element code FORGE. The punch load and thickness distribution of AZ31 sheet have been studied. The study of the results is helpful to the application of the stamping technology for the magnesium alloy sheet.

  19. Interfacial reaction in squeeze cast SiCw/AZ91 magnesium alloy composite

    SciTech Connect

    Wu, K.; Zheng, M.; Zhao, M.; Yao, C.; Li, J.

    1996-08-15

    It is well known that the interface between the matrix and the reinforcement plays an important role in the properties of metal matrix composites (MMCs). Interfacial structure and its effect on the properties of aluminum matrix composites have been extensively studied. The interface of Mg-MMCs is very different from that of Al-MMCs, due to high reactivity of magnesium. As magnesium have natural affinity for wetting or bonding to ceramic reinforcement, and furthermore, magnesium does not form any carbides, SiC is one of the most suitable reinforcement for magnesium matrix composite, SiCw/AZ91 magnesium matrix composites have excellent properties compared with other discontinuously reinforced Mg-MMCs. The aim of the present study is to investigate the interfacial reactions in SiCw/AZ91 composites prepared by squeeze casting method, with particular emphasis on the morphology, structure and the formation mechanisms of the reaction products using electron microscopy, in order to provide a better understanding of the relationship between the interfacial structure and the properties of the composites.

  20. Mechanical behaviour of magnesium alloy AZ91D using split Hopkinson tensile bar (SHTB)

    NASA Astrophysics Data System (ADS)

    Ahmad, I. R.; Shu, D. Wei

    2010-03-01

    Magnesium alloys have been increasingly used in the automobile, communication and aerospace industries due to their low density, high specific strength and good castability. Higher speed in vehicles, development in weaponry and high speed metal working all are characterized with high rates of loading. In current study, a cast magnesium alloys AZ91D has been investigated at strain rates in the range between 300 s-1 and 1250 s-1. Relatively uniform strain rates are observed at lower strain rates. However an exception is observed for maximum strain rate tested, where a nearly constant strain rate of 1252 s-1 is observed over most of the test duration. Approximately 25% increase in stress is noticed at a strain rate of 1252 s-1 as compare to the stress at a strain rate of 346 s-1. The alloy AZ91D is observed to be more strain rate sensitive for strain rate higher than 1000 s-1. A decrease in strain rate sensitivity is observed with increasing percentage strain in the specimen.

  1. Mechanical behaviour of magnesium alloy AZ91D using split Hopkinson tensile bar (SHTB)

    NASA Astrophysics Data System (ADS)

    Ahmad, I. R.; Shu, D. Wei

    2009-12-01

    Magnesium alloys have been increasingly used in the automobile, communication and aerospace industries due to their low density, high specific strength and good castability. Higher speed in vehicles, development in weaponry and high speed metal working all are characterized with high rates of loading. In current study, a cast magnesium alloys AZ91D has been investigated at strain rates in the range between 300 s-1 and 1250 s-1. Relatively uniform strain rates are observed at lower strain rates. However an exception is observed for maximum strain rate tested, where a nearly constant strain rate of 1252 s-1 is observed over most of the test duration. Approximately 25% increase in stress is noticed at a strain rate of 1252 s-1 as compare to the stress at a strain rate of 346 s-1. The alloy AZ91D is observed to be more strain rate sensitive for strain rate higher than 1000 s-1. A decrease in strain rate sensitivity is observed with increasing percentage strain in the specimen.

  2. Project W-151 Tank 101-AZ Waste Retrieval System Year 2000 Compliance Assessment Project Plan

    SciTech Connect

    BUSSELL, J.H.

    1999-08-02

    This assessment describes the potential Year 2000 (Y2K) problems and describes the methods for achieving Y2K compliance for Project W-151, Tank 101-AZ Waste Retrieval System. The purpose of this assessment is to give an overview of the project. This document will not be updated and any dates contained in this document are estimates and may change. Two mixer pumps and instrumentation have been or are planned to be installed in waste tank 101-AZ to demonstrate solids mobilization. The information and experience gained during this process test will provide data for comparison with sludge mobilization prediction models and provide indication of the effects of mixer pump operation on an Aging Waste Facility tank. A limited description of system dates, functions, interfaces, potential Y2K problems, and date resolutions is presented. The project is presently on hold, and definitive design and procurement have been completed. This assessment will describe the methods, protocols, and practices to ensure that equipment and systems do not have Y2K problems.

  3. Histone H2A.Z deregulation in prostate cancer. Cause or effect?

    PubMed

    Dryhurst, Deanna; Ausi, Juan

    2014-09-01

    Genetic and epigenetic changes are at the root of all cancers. The epigenetic component involves alterations of the post-synthetic modifications of DNA (methylation) and histones (histone posttranslational modifications, PTMs) as well as of those of their molecular "writers," "readers," and "erasers." Noncoding RNAs (ncRNA) can also play a role. Here, we focus on the involvement of histone alterations in cancer, in particular that of the histone variant H2A.Z in the etiology of prostate cancer. The structural mechanisms putatively responsible for the contribution of H2A.Z to oncogenic gene expression programs are first described, followed by what is currently known about the involvement of this histone variant in the regulation of androgen receptor regulated gene expression. The implications of this and their relevance to oncogene deregulation in different stages of prostate cancer, including the progression toward androgen independence, are discussed. This review underscores the increasing awareness of the epigenetic contribution of histone variants to oncogenic progression. PMID:24398858

  4. Characterization of AZ31B wrought magnesium alloy joints welded by high power fiber laser

    SciTech Connect

    Wang Zemin; Gao Ming Tang Haiguo; Zeng Xiaoyan

    2011-10-15

    A 6 kW fiber laser is used to weld AZ31B wrought magnesium alloy and the characterization of welded joints are studied by the observations of bead size, microstructure and mechanical properties. The accepted joints without macro-defects can be obtained when the laser power is in the range of 2.5 to 4.0 kW. Typical hexagonal dendrites are observed in the fusion zone, whose average semi-axis length increases with increasing heat input or decreasing welding speed. The minimum ultimate tensile strength of welded joints reaches 227 MPa, 94.6% of the base metal. And when the heat input reduces to 48 J/mm or lower, the joints are fractured in the base metal, showing stronger failure strength compared to the base metal. For the joints ruptured in the weld metal, the fracture surface is characterized by a ductile-brittle mixed pattern consisting of both dimples and cleavages. Finally, the formation mechanism of pore in the welds is discussed and summarized by the pore morphologies on the fracture surface. - Highlights: {yields} Accepted joints of AZ31B Mg alloy are produced by high power fiber laser. {yields} Optimal welding parameters are summarized by experimental observations. {yields} Obvious hexagonal dendrites are observed in the fusion zone. {yields} The joints are stronger than base metal as the heat input is lower than 48 J/mm. {yields} Pore formation mechanism of welded joints is discussed and summarized.

  5. Forming Analysis of AZ31 Magnesium Alloy Sheets by Means of a Multistep Inverse Approach

    SciTech Connect

    Nguyen, Ba Nghiep; Bapanapalli, Satish K.

    2009-04-01

    This paper applies a multi-step inverse approach to predict the forming of AZ31 magnesium alloy sheets. An in-house finite element code named INAPH, which implements the inverse approach formulation by Guo et al. (Int. J. Numer. Methods Eng., 30, 1385-1401), has been used for the forming analysis. This inverse approach uses the deformation theory of plasticity and assumes that the deformation is independent of the loading history. Failure during forming is predicted by a stress-based criterion or a forming limit diagram-based criterion. The INAPH predictions have been compared with experimental results of Takuda et al (Journal of Materials Processing Technology, 89-90:135-140) and incremental analysis using ABAQUS. The multi-step inverse analysis has been shown to very quickly and fairly accurately predict stress, plastic strain, thickness distributions and failure locations on deeply drawn parts made of AZ31 magnesium alloy. The capability of INAPH to predict the formability of magnesium alloys has also been demonstrated at various temperatures. As magnesium alloys possess very limited formability at room temperature, and their formability becomes better at higher temperatures (> 100oC), the inverse analysis constitutes an efficient and valuable tool to predict forming of magnesium alloy parts as a function of temperature. In addition, other processing and design parameters such as the initial dimensions, final desired shape, blank holder forces, and friction can be quickly adjusted to assess the forming feasibility.

  6. Surface composite nanostructures of AZ91 magnesium alloy induced by high current pulsed electron beam treatment

    NASA Astrophysics Data System (ADS)

    Li, M. C.; Hao, S. Z.; Wen, H.; Huang, R. F.

    2014-06-01

    High current pulsed electron beam (HCPEB) treatment was conducted on an AZ91 cast magnesium alloy with accelerating voltage 27 kV, energy density 3 J/cm2 and pulse duration 2.5 ?s. The surface microstructure was characterized by optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), and transmission electron microscope (TEM). The surface corrosion property was tested with electrochemical method in 3.5 wt.% NaCl solution. It is found that after 1 pulse of HCPEB treatment, the initial eutectic ? phase and Mg17Al12 particles started to dissolve in the surface modified layer of depth 15 ?m. When using 15 HCPEB pulses, the Al content in surface layer increased noticeably, and the phase structure was modified as composite nanostructures consisted of nano-grained Mg3.1Al0.9 domains surrounded by network of Mg17Al12 phase. The HCPEB treated samples showed an improved corrosion resistance with cathodic current density decreased by two orders of magnitude as compared to the initial AZ91 alloy.

  7. Fatigue properties of magnesium alloy AZ91 processed by severe plastic deformation.

    PubMed

    Fintov, Stanislava; Kunz, Ludvk

    2015-02-01

    Fatigue properties of cast AZ91 magnesium alloy processed by severe plastic deformation were investigated and compared with the properties of the initial cast state. The severe plastic deformation was carried out by equal channel angular pressing (ECAP). The ECAP treatment resulted in a bimodal structure. The bimodality consists in a coexistence of fine grained areas with higher content of Mg17Al12 particles and areas exhibiting larger grains and lower density of Mg17Al12 particles. Improvement of the basic mechanical properties of AZ91 (yield stress, tensile strength and ductility) by ECAP was significant. Also the improvement of the fatigue life in the low-cycle fatigue region was substantial. However the improvement of the fatigue strength in the high-cycle fatigue region was found to be negligible. The endurance limit based on 10(7) cycles for the cast alloy was 80 MPa and for the alloy processed by ECAP 85 MPa. The cyclic plastic response in both states was qualitatively similar; initial softening was followed by a long cyclic hardening. Fatigue cracks in cast alloy initiate in cyclic slip bands which were formed in areas of solid solution. In the case of severe plastic deformed material with bimodal structure two substantially different mechanisms of crack initiation were observed. Crack initiation in slip bands was a preferred process in the areas with large grains whereas the grain boundaries cracking was a characteristic mechanism in the fine grained regions. PMID:25498295

  8. Corrosion behavior of magnesium alloy AZ91 and its MMC in NaCl solution

    SciTech Connect

    Chan, W.M.; Cheng, F.T.; Leung, L.K.; Horylev, R.J.; Yue, T.M.

    1997-12-01

    The corrosion behaviors of magnesium alloy AZ91C and its Al{sub 2}O{sub 3}(short fiber)-reinforced metal matrix composite (MMC) in alkaline solutions (pH 10.5) containing chloride were compared using potentiodynamic polarization measurements, electrochemical impedance spectroscopy (EIS) and immersion tests. Dependence of polarization characteristics (corrosion potential and corrosion current density) on chloride concentration was similar for both materials. The corrosion potential E{sub corr} decreased linearly with the logarithm of chloride concentration, while the corrosion current density i{sub corr} increased rapidly at chloride concentrations larger than 0.1%, with the i{sub corr} for the MMC consistently higher than that for AZ91C, reaching a factor of about 3 in3.5% sodium chloride solution. EIS data indicated that the protective film on the MMC was inferior to that on the matrix alloy. With stirring and at frequencies higher than 5 Hz, the electrode/electrolyte interface might be described by the simplified Randles model for both materials. Immersion tests showed that the corrosion rate of the MMC, in terms of weight loss, was about 7 times that of the matrix alloy. Thus the present investigation indicated that in alkaline solutions containing chloride ions, the presence of Al{sub 2}O{sub 3} short fibers in the alloy did not drastically alter the corrosion behavior, but significantly reduced its corrosion resistance.

  9. Studies of the AZ91 magnesium alloy / SiO2-coated carbon fibres composite microstructure

    NASA Astrophysics Data System (ADS)

    Olszwka-Myalska, A.; Botor-Probierz, A.

    2010-02-01

    The microstructure of magnesium matrix composite reinforced with SiO2nano-layer coated carbon fibres, deposited by sol-gel method was characterized. The composite was obtained by infiltration method and the effect of SiO2 on the composite microstructure was analyzed by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM+EDS) and transmission electron microscopy combined with energy-dispersive X-ray spectroscopy (TEM+EDS) methods. Good wettability of fibres by the magnesium alloy AZ91 (Al 9 wt%, Zn 0.3 wt%) was confirmed since fibres were closely surrounded with alloy and pulling-out effect was not visible. The interface region was evidently with aluminium enriched. Near carbon fibre surface a regular layer of SiOX oxide enriched with Al was detected by high angle annular dark field image (HAADF) combined with energy-dispersive X-ray spectroscopy (EDS). The plate or needle shaped very fine particles of Al12Mg17 were identified near the AZ91 matrix zone by bright field (BF) and selected area electron diffraction (SADP).

  10. Identification of an advanced constitutive model of Magnesium alloy AZ31B

    SciTech Connect

    Liu, Z. G.; Massoni, E.

    2011-05-04

    The main aim of this paper is to study the flow behavior of the AZ31B magnesium alloy by means of tensile tests performed in extended ranges of temperature and strain rates. The flow stress-strain curves analyzed by power law type constitutive equation can only fit well with experimental curves at the work-hardening stage. A new mathematical model is studied to describe the softening behavior of material based on tensile experiments. The relative parameters are obtained by fitting the equation with the experimental data. The genetic algorithm has been used to obtain the global optimal fitting parameters. The comparison between the fitted and experimental data proves the effectiveness of the model. The results indicate that this model leads to a better simulation of the flow stress during the softening stage than that of the power law equation. Based on this model, the deep drawing process has been simulated with the commercial finite element code FORGE registered. The punch load and thickness distribution of AZ31 sheet have been studied. The study of the results is helpful to the application of the stamping technology for the magnesium alloy sheet.

  11. Experimental investigation of anisotropy evolution of AZ31 magnesium alloy sheets under tensile loading

    SciTech Connect

    Tari, D. Ghaffari; Worswick, M. J.

    2011-05-04

    Increasing demand for lighter final products has created new opportunities for the application of new light weight materials. Due to high strength to density ratio and good magnetic resistance properties, magnesium alloys are good candidates to replace steel and aluminum for same application. However, limited numbers of active slip deformation mechanisms, result in a decreased formability at room temperature. Furthermore, wrought magnesium alloys have an initial crystallographic texture, remained from the prior rolling operations, which makes them highly anisotropic. In this paper, tensile tests are performed at room temperature and 200 deg. C at different strain rates and orientations relative to the rolling direction, including rolling, 30 deg., 45 deg., 60 deg. and transverse orientation. The strain rates adopted for these experiments varied from 0.001 to 1.0. The testing results show the effect of temperature on the strain rate sensitivity of AZ31 sheets. The extent of deformation is continuously recorded using two separate high temperature extensometers. The results of testing show an increase in the r-values with the plastic deformation. The strain rate sensitivity of AZ31 increased as the temperature was elevated. At higher strain rates the measured r-values are larger and the slope of its evolution with the plastic strain is steeper.

  12. Archaeological data recovery at drill hole U19az, Nevada Test Site, Nye County, Nevada

    SciTech Connect

    Lancaster, J.

    1992-12-31

    At the request of the Department of Energy, Nevada Field Office (DOE/NV), the Desert Research Institute (DRI) conducted archaeological data recovery at drill hole U19az on the Nevada Test Site in February 1988 and April 1990. The work focused on a site that was recommended as eligible to the National Register of Historic Places. DOE/NV chose to mitigate adverse impacts to the site though a data recovery program. The mapping and collection of artifacts took place in two discrete areas, covering almost 10 hectares (24.71 acres). In addition to surface collection, 11 test pits and 12 surface scrapes were excavated. Information was sought to address four research questions concerned with the age of the site, the subsistence and demography of the site`s inhabitants, and the behavioral implications of their lithic technology. This report describes and presents the results of the data recovery at drill hole U19az. The analyses of the artifacts indicate that the site was inhabited between 5,000 years ago and historic times. Relative artifact abundance indicates the most intense use occurred from about 4,000 to 1,500 years ago.

  13. Effect of Heat Treatment on Fracture Toughness of As-Forged AZ80 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Deng, Min; Li, Hui-Zhong; Tang, Si-Nan; Liao, Hui-Juan; Liang, Xiao-Peng; Liu, Ruo-Mei

    2015-05-01

    The effect of heat treatment on the plane-strain fracture toughness in forged AZ80 magnesium alloy was studied. Two different kinds of heat treatment technologies (T5 and T6) were performed on the forged samples. The values of plane-strain fracture toughness ( K IC) were obtained from the stretched zone (SZ for short) analysis. The results showed that the as-forged specimen would produce a large quantity of ?-Mg17Al12 precipitates both in the interior of the grains and at grain boundaries after T5 and T6 heat treatments. The ?-Mg17Al12 displayed a precipitation strengthening. Compared with the as-forged specimen, the ultimate tensile strengths of T5 and T6 specimens were improved by 42.8 and 30 MPa, respectively. And the K IC of T5 and T6 specimens also increased to 23.8 and 21.0 MPa m1/2 while that of the as-forged sample was 17.9 MPa m1/2. The average grain size of T5 sample was similar to that of the as-forged one, but was finer than that of T6 specimen. The best mechanical properties and fracture toughness of forged AZ80 magnesium alloy were achieved after T5 treatment.

  14. Physical properties of the extreme Centaur and super-comet candidate 2013 AZ60

    NASA Astrophysics Data System (ADS)

    Pl, A.; Kiss, Cs.; Horner, J.; Szakts, R.; Vilenius, E.; Mller, Th. G.; Acosta-Pulido, J.; Licandro, J.; Cabrera-Lavers, A.; Srneczky, K.; Szab, Gy. M.; Thirouin, A.; Sip?cz, B.; Dzsa, .; Duffard, R.

    2015-11-01

    We present estimates of the basic physical properties including size and albedo of the extreme Centaur 2013 AZ60. These properties have been derived from optical and thermal infrared measurements. Our optical measurements revealed a probable full period of ?9.4 h with a shallow amplitude of 4.5%. By combining optical brightness information and thermal emission data, we are able to derive a diameter of 62.3 5.3 km and a geometric albedo of 2.9%, which corresponds to an extremely dark surface. Additionally, our finding of ?50 Jm-2 K-1 s- 1/2 for the thermal inertia is also remarkable for objects in such a distance. The results of dynamical simulations yield an unstable orbit, with a 50% probability that the target will be ejected from the solar system within 700 000 yr. The current orbit of this object and its instability could imply a pristine cometary surface. This possibility agrees with the observed low geometric albedo and red photometric colour indices for the object, which match the surface of a dormant comet well, as would be expected for a long-period cometary body approaching perihelion. Although it was approaching ever closer to the Sun, however, the object exhibited star-like profiles in each of our observations, lacking any sign of cometary activity. According to the albedo, 2013 AZ60 is a candidate for the darkest body among the known trans-Neptunian objects.

  15. Microstructural and textural evolution of AZ61 magnesium alloy sheet during bidirectional cyclic bending

    SciTech Connect

    Huo, Qinghuan; Yang, Xuyue Ma, Jijun; Sun, Huan; Qin, Jia; Jiang, Yupei

    2013-05-15

    In this work, the microstructural and textural evolution in the sheets of AZ61 magnesium alloy was studied by means of bidirectional cyclic bending for 8 passes at 623 K. The bended samples were examined by optical microscopy and electron backscatter diffraction analysis. The results showed that a gradient structure with fine grains about 3 μm in the regions near two surfaces and, in contrast, coarse grains in the middle of the sheet were formed. The evident grain refinement was attributed to twin-assisted dynamic recrystallization and continuous dynamic recrystallization induced by kink bands. The texture intensity was clearly reduced, resulting in a negative gradient distribution, with the texture intensity decreases from the center of the sheet to two surfaces. The weakened texture greatly facilitated the reduction of the yield strength. A higher fracture elongation and a slightly improved ultimate tensile strength were achieved concurrently. - Highlights: • The AZ61 Mg alloy is deformed at 623 K by bidirectional cyclic bending. • A symmetric gradient distribution of fine grains along the thickness is formed. • The basal texture in the regions near two surfaces is weakened significantly.

  16. Laser surface modification of AZ31B Mg alloy for bio-wettability.

    PubMed

    Ho, Yee-Hsien; Vora, Hitesh D; Dahotre, Narendra B

    2015-02-01

    Magnesium alloys are the potential degradable materials for load-bearing implant application due to their comparable mechanical properties to human bone, excellent bioactivity, and in vivo non-toxicity. However, for a successful load-bearing implant, the surface of bio-implant must allow protein absorption and layer formation under physiological environment that can assist the cell/osteoblast growth. In this regard, surface wettability of bio-implant plays a key role to dictate the quantity of protein absorption. In light of this, the main objective of the present study was to produce favorable bio-wettability condition of AZ31B Mg alloy bio-implant surface via laser surface modification technique under various laser processing conditions. In the present efforts, the influence of laser surface modification on AZ31B Mg alloy surface on resultant bio-wettability was investigated via contact-angle measurements and the co-relationships among microstructure (grain size), surface roughness, surface energy, and surface chemical composition were established. In addition, the laser surface modification technique was simulated by computational (thermal) model to facilitate the prediction of temperature and its resultant cooling/solidification rates under various laser processing conditions for correlating with their corresponding composition and phase evolution. These predicted thermal properties were later used to correlate with the corresponding microstructure, chemical composition, and phase evolution via experimental analyses (X-ray diffractometer, scanning electron microscope, energy-dispersive spectroscopy). PMID:25201909

  17. Geologie study off gravels of the Agua Fria River, Phoenix, AZ

    USGS Publications Warehouse

    Langer, W.H.; Dewitt, E.; Adams, D.T.; O'Briens, T.

    2010-01-01

    The annual consumption of sand and gravel aggregate in 2006 in the Phoenix, AZ metropolitan area was about 76 Mt (84 million st) (USGS, 2009), or about 18 t (20 st) per capita. Quaternary alluvial deposits in the modern stream channel of the Agua Fria River west of Phoenix are mined and processed to provide some of this aggregate to the greater Phoenix area. The Agua Fria drainage basin (Fig. 1) is characterized by rugged mountains with high elevations and steep stream gradients in the north, and by broad alluvial filled basins separated by elongated faultblock mountain ranges in the south. The Agua Fria River, the basin’s main drainage, flows south from Prescott, AZ and west of Phoenix to the Gila River. The Waddel Dam impounds Lake Pleasant and greatly limits the flow of the Agua Fria River south of the lake. The southern portion of the watershed, south of Lake Pleasant, opens out into a broad valley where the river flows through urban and agricultural lands to its confluence with the Gila River, a tributary of the Colorado River.

  18. Effects of heat input on microstructure and tensile properties of laser welded magnesium alloy AZ31

    SciTech Connect

    Quan, Y.J. Chen, Z.H.; Gong, X.S.; Yu, Z.H.

    2008-10-15

    A 3 kW CO{sub 2} laser beam was used to join wrought magnesium alloy AZ31 sheets, and the effects of heat input on the quality of butt welding joints were studied. By macro and microanalysis, it is found that the welding heat input plays an important role in laser welding process for AZ31 wrought sheets. After welding, the grains far from the weld centre present the typical rolled structure. But the microstructure out of the fusion zone gradually changes to complete equiaxed crystals as the distance from the weld centre decreases. Adjacent to the fusion boundary, there is a band region with columnar grains, and its growth direction is obviously perpendicular to the solid/liquid line. The microstructure in fusion centre consists of fine equiaxed grains and the many precipitated particles are brittle phase Mg{sub 17}Al{sub 12} or Mg{sub 17}(Al,Zn){sub 12}. With increasing the heat input, the band width of columnar grains varies, the grains in fusion zone get coarser, and the distribution of precipitates changes from intragranularly scattered particles to intergranularly packed ones. The results of tensile test show that the change trend of ultimate tensile strength (UTS) and elongation of the welded joints is to increase at first and then decrease with the heat input increasing. When the heat input reaches 24 J mm{sup -1}, the maximum value of the UTS is up to 96.8% of the base metal.

  19. Electrophoretic deposition of nanostructured hydroxyapatite coating on AZ91 magnesium alloy implants with different surface treatments

    NASA Astrophysics Data System (ADS)

    Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

    2013-11-01

    Bio-absorbable magnesium (Mg) based alloys have been introduced as innovative orthopedic implants during recent years. It has been specified that rapid degradation of Mg based alloys in physiological environment should be restrained in order to be utilized in orthopedic trauma fixation and vascular intervention. In this developing field of healthcare materials, micro-arc oxidation (MAO), and MgF2 conversion coating were exploited as surface pre-treatment of AZ91 magnesium alloy to generate a nanostructured hydroxyapatite (n-HAp) coating via electrophoretic deposition (EPD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) techniques were used to characterize the obtained powder and coatings. The potentiodynamic polarization tests were carried out to evaluate the corrosion behavior of the coated and uncoated specimens, and in vitro bioactivity evaluation were performed in simulated body fluid. Results revealed that the MAO/n-HAp coated AZ91 Mg alloy samples with a rough topography and lower corrosion current density leads to a lower Mg degradation rate accompanied by high bioactivity.

  20. Low dose of the liver X receptor agonist, AZ876, reduces atherosclerosis in APOE*3Leiden mice without affecting liver or plasma triglyceride levels

    PubMed Central

    van der Hoorn, JWA; Lindn, D; Lindahl, U; Bekkers, MEA; Voskuilen, M; Nilsson, R; Oscarsson, J; Lindstedt, EL; Princen, HMG

    2011-01-01

    BACKGROUND AND PURPOSE Liver X receptor (LXR) agonists are atheroprotective but often induce hypertriglyceridaemia and liver steatosis. We investigated the effect of a novel high-affinity LXR activator, AZ876, on plasma lipids, inflammation and atherosclerosis, and compared the effects with another LXR agonist, GW3965. EXPERIMENTAL APPROACH APOE*3Leiden mice were fed an atherogenic diet alone or supplemented with either AZ876 (5 or 20 molkg?1day?1) or GW3965 (17 molkg?1day?1) for 20 weeks. Total cholesterol and triglyceride levels were measured using commercial kits. Plasma cytokines were determined by using bead-based multiplex suspension array kits with the Luminex technology. Atherosclerosis was assessed histochemically and lesion composition was assessed by immunohistochemical methods. KEY RESULTS Low-dose AZ876 had no effect on plasma or liver lipids, whereas high-dose AZ876 increased plasma triglycerides (+110%) and reduced cholesterol (?16%) compared with controls. GW3965 increased plasma triglycerides (+70%). Low-dose AZ876 reduced lesion area (?47%); and high-dose AZ876 strongly decreased lesion area (?91%), lesion number (?59%) and severity. In either dose, AZ876 did not affect lesion composition. GW3965 reduced atherosclerosis and collagen content of lesions (?23%; P < 0.01). High-dose AZ876 and GW3965, but not low-dose AZ876, reduced inflammation as reflected by lower cytokine levels and vessel wall activation. CONCLUSIONS AND IMPLICATIONS We have identified a novel LXR agonist that when given in a low dose inhibits the progression of atherosclerosis without inducing anti-inflammatory effects, liver steatosis or hypertriglyceridaemia. Therefore, the primary protective action of a low-dose AZ876 is likely to be an increased reverse cholesterol transport. PMID:21175581

  1. SAFETY ANALYSIS FOR TANK 241-AZ-101 MIXER PUMP PROCESS TEST

    SciTech Connect

    HAMMOND DM; HARRIS JP; MOUETTE P

    1997-06-09

    This document contains the completed safety analysis which establishes the safety envelope for performing the mixer pump process test in Tank 241-AZ-101. This process test is described in TF-210-OTP-001. All equipment necessary for the mixer pump test has been installed by Project W-151. The purpose of this document is to describe and analyze the mixer pump test for Aging Waste Facility (AWF) Tank 241-AZ-101 and to address the 'yes/maybe' responses marked for evaluation questions identified in Unreviewed Safety Question Evaluation (USQE) TF-94-0266. The scope of this document is limited to the performance of the mixer pump test for Tank 241-AZ-101. Unreviewed Safety Question Determination (USQD) TF-96-0018 verified that the installation of two mixer pumps into Tank 241-AZ-101 was within the current Tank Waste Remediation System (TWRS) Authorization Basis. USQDs TF-96-0461, TF-96-0448, and TF-96-0805 verified that the installation of the in-tank video camera, thermocouples, and Ultrasonic Interface Level Analyzer (URSILLA), respectively, were within the current TWRS Authorization Basis. USQD TF-96-1041 verified that the checkout testing of the installed equipment was within the current TWRS Authorization Basis. Installation of the pumps and equipment has been completed. An evaluation of safety considerations associated with operation of the mixer pumps for the mixer pump test is provided in this document. This document augments the existing AWF authorization basis as defined in the Interim Safety Basis (Stahl 1997), and as such, will use the existing Interim Operational Safety Requirements (IOSRs) of Heubach 1996 to adequately control the mixer pump test. The hazard and accident analysis is limited to the scope and impact of the mixer pump test, and therefore does not address hazards already addressed by the current AWF authorization basis. This document does not evaluate removal of the mixer pumps. Safety considerations for removal of the pumps will be addressed by separate safety documentation once that portion of the mission is defined. The mixer pump test has been evaluated to cover the use of either the existing ventilation system (241-A-702) or the ventilation system upgrade provided by Project W-030. Analysis of Project W-030 is outside of the scope of this document and is addressed in HNF-SD-WM-SARR-039 (Draft) which, should the W-030 system be in service at the time of the mixer pump test, will have been approved and made a part of the TWRS authorization basis. The test will use two high-capacity mixer pumps in various configurations and modes to demonstrate solids mobilization of waste in Tank 241-AZ-101. The information and experience gained during the test will provide data for comparison with sludge mobilization prediction models; provide data to estimate the number, location, and cycle times of the mixer pumps; and provide indication of the effects of mixer pump operation on the AWF tank systems and components. The slurry produced will be evaluated for future pretreatment processing. This process test does not transfer waste from the tank; the waste is mixed and confined within the existing system. At the completion of the mixer pump test, the mixer pumps will be stopped and normal tank operations, maintenance, and surveillance will continue. Periodic rotation of the mixer pumps and motor shafts, along with bearing greasing, is required to maintain the pumps following the mixer pump test.

  2. 76 FR 54288 - Notice of Final Federal Agency Actions on Proposed Bridge and Approach Roadways in Nevada and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-31

    ... Federal Highway Administration Notice of Final Federal Agency Actions on Proposed Bridge and Approach... proposed Laughlin-Bullhead City Bridge project in Laughlin, Clark County, Nevada; and in Bullhead City... claim seeking judicial review of the Federal agency actions on the bridge and roadway project will...

  3. Great cities look small

    PubMed Central

    Sim, Aaron; Yaliraki, Sophia N.; Barahona, Mauricio; Stumpf, Michael P. H.

    2015-01-01

    Great cities connect people; failed cities isolate people. Despite the fundamental importance of physical, face-to-face social ties in the functioning of cities, these connectivity networks are not explicitly observed in their entirety. Attempts at estimating them often rely on unrealistic over-simplifications such as the assumption of spatial homogeneity. Here we propose a mathematical model of human interactions in terms of a local strategy of maximizing the number of beneficial connections attainable under the constraint of limited individual travelling-time budgets. By incorporating census and openly available online multi-modal transport data, we are able to characterize the connectivity of geometrically and topologically complex cities. Beyond providing a candidate measure of greatness, this model allows one to quantify and assess the impact of transport developments, population growth, and other infrastructure and demographic changes on a city. Supported by validations of gross domestic product and human immunodeficiency virus infection rates across US metropolitan areas, we illustrate the effect of changes in local and city-wide connectivities by considering the economic impact of two contemporary inter- and intra-city transport developments in the UK: High Speed 2 and London Crossrail. This derivation of the model suggests that the scaling of different urban indicators with population size has an explicitly mechanistic origin. PMID:26179988

  4. Great cities look small.

    PubMed

    Sim, Aaron; Yaliraki, Sophia N; Barahona, Mauricio; Stumpf, Michael P H

    2015-08-01

    Great cities connect people; failed cities isolate people. Despite the fundamental importance of physical, face-to-face social ties in the functioning of cities, these connectivity networks are not explicitly observed in their entirety. Attempts at estimating them often rely on unrealistic over-simplifications such as the assumption of spatial homogeneity. Here we propose a mathematical model of human interactions in terms of a local strategy of maximizing the number of beneficial connections attainable under the constraint of limited individual travelling-time budgets. By incorporating census and openly available online multi-modal transport data, we are able to characterize the connectivity of geometrically and topologically complex cities. Beyond providing a candidate measure of greatness, this model allows one to quantify and assess the impact of transport developments, population growth, and other infrastructure and demographic changes on a city. Supported by validations of gross domestic product and human immunodeficiency virus infection rates across US metropolitan areas, we illustrate the effect of changes in local and city-wide connectivities by considering the economic impact of two contemporary inter- and intra-city transport developments in the UK: High Speed 2 and London Crossrail. This derivation of the model suggests that the scaling of different urban indicators with population size has an explicitly mechanistic origin. PMID:26179988

  5. City Lights of Europe

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Growth in 'mega-cities' is altering the landscape and the atmosphere in such a way as to curtail normal photosynthesis. By using data from The Defense Meteorological Satellite Program's Operational Linescan System, researchers have been able to look at urban sprawl by monitoring the emission of light from cities at night. By overlaying these 'light maps' onto other data such as soil and vegetation maps, the research shows that urbanization can have a variable but measurable impact on photosynthetic productivity. For more information, read Bright Lights, Big City Image by the NASA GSFC Scientific Visualization Studio

  6. Histone H2A.Z controls a critical chromatin remodeling step required for DNA double-strand break repair.

    PubMed

    Xu, Ye; Ayrapetov, Marina K; Xu, Chang; Gursoy-Yuzugullu, Ozge; Hu, Yiduo; Price, Brendan D

    2012-12-14

    Chromatin remodeling during DNA double-strand break (DSB) repair is required to facilitate access to and repair of DSBs. This remodeling requires increased acetylation of histones and a shift in nucleosome organization to create open, relaxed chromatin domains. However, the underlying mechanism driving changes in nucleosome structure at DSBs is poorly defined. Here, we demonstrate that histone H2A.Z is exchanged onto nucleosomes at DSBs by the p400 remodeling ATPase. H2A.Z exchange at DSBs shifts the chromatin to an open conformation and is required for acetylation and ubiquitination of histones and for loading of the brca1 complex. H2A.Z exchange also restricts single-stranded DNA production by nucleases and is required for loading of the Ku70/Ku80 DSB repair protein. H2A.Z exchange therefore promotes specific patterns of histone modification and reorganization of the chromatin architecture, leading to the assembly of a chromatin template that is an efficient substrate for the DSB repair machinery. PMID:23122415

  7. 77 FR 23496 - Notice of Relocation of the Bureau of Land Management's Tucson Field Office in Tucson, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-19

    ... Bureau of Land Management Notice of Relocation of the Bureau of Land Management's Tucson Field Office in Tucson, AZ AGENCY: Bureau of Land Management, Interior. ACTION: Notice of relocation. SUMMARY: This notice announces the relocation of the Bureau of Land Management's (BLM) Tucson Field Office (TFO)...

  8. Warm Deep Drawing of Rectangular Parts of AZ31 Magnesium Alloy Sheet Adopting Variable Blank Holder Force

    NASA Astrophysics Data System (ADS)

    Ying-hong, Peng; Qun-feng, Chang; Da-yong, Li; Xiao-qin, Zeng

    2007-05-01

    AZ31 magnesium alloy sheet with good shape and formability is fabricated by warm cross rolling. Uniaxial tensile tests are conducted using a Gleeble 3500 thermal - mechanical simulator, and the mechanical properties of AZ31 magnesium alloy sheet are analyzed. A warm deep drawing process of square part is also simulated by the finite element method. The influences of blank holder force on the formability are numerically investigated. A double-action hydraulic press that can realize adjustable blank holder forces is developed and its working principle and control system are introduced. Some warm deep drawing experiments of square parts of AZ31 magnesium alloy sheet are also performed. Different variation schemes of the blank holder force with the stroke of the punch are tested, and the experiment results are compared. Results show that the suitable blank holder force variation scheme is a ladder curve with the punch stroke. Adopting the variable blank holder force technique can improve 13.2% of the drawing depth of square parts of AZ31 magnesium alloy sheet.

  9. Brightness Variation and Companion Analysis of AZ Capricorni --- A Low-Mass Member in the Beta Pictoris Moving Group

    NASA Astrophysics Data System (ADS)

    Chen, Chang Yao; Chen, Wen-Ping

    2015-08-01

    AZ Capricorni (BD-17o 6128) is a low-mass member of the Beta Pictoris moving group, which consists of 55 known stellar systems sharing similar space moving motion as that of Beta Pic, the prototypical star with a prominent planetary debris disk. AZ Cap is a known X-ray source signifying its chromospheric activity. We present the three-year light curve of the star from 2010 to 2012. The 3.4 d period previously reported (Messina et al. 2010) is confirmed. The star was particularly active in 2011 with amplified brightness modulation. AZ Cap is known to have a close companion (Neuhäuser et al. 2002), which not only may confuse the X-ray source identification but, if bound to AZ Cap, would add to the inventory of the group membership. Astrometric measurements of DSS images, Pan-STARRS 1 images, and images taken by ourselves, at three epochs spanning 60 years, led to the conclusion that it is not a physical pair.

  10. 75 FR 76924 - Modification of Class D and E Airspace, and Revocation of Class E Airspace; Flagstaff, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-10

    ... removes Class E airspace designated as an extension to a Class D or E surface area at Flagstaff Pulliam... remove Class E airspace designated as an extension to a Class D or E surface area at Flagstaff, AZ and to modify the Class D and E controlled airspace at Flagstaff Pulliam Airport (75 FR 61660)....

  11. ARSENIC REMOVAL FROM DRINKING WATER BY ADSORPTIVE MEDIA USEPA DEMONSTRATION PROJECT AT VALLEY VISTA, AZ SIX-MONTH EVALUATION REPORT

    EPA Science Inventory

    This report documents the activities performed and the results obtained from the first six months of the EPA arsenic removal technology demonstration project at the Arizona Water Company (AWC) facility in Sedona, AZ, commonly referred to as Valley Vista. The main objective of the...

  12. 76 FR 70957 - Foreign-Trade Zone 277-Western Maricopa County, AZ; Application for Manufacturing Authority, Sub...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-16

    ... Foreign-Trade Zones Board Foreign-Trade Zone 277--Western Maricopa County, AZ; Application for... submitted to the Foreign-Trade Zones Board (the Board) by the Greater Maricopa County Foreign Trade Zone...- Trade Zones Act, as amended (19 U.S.C. 81a-81u), and the regulations of the Board (15 CFR part 400)....

  13. 76 FR 62760 - Foreign-Trade Zone 277-Western Maricopa County, AZ; Application for Temporary/Interim...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-11

    .../Interim Manufacturing Authority; Sub-Zero, Inc.; (Refrigerators); Goodyear, AZ An application has been... (Site 3). Under T/IM procedures, Sub-Zero has requested authority to produce refrigerators (HTSUS 8418... 45% of the value of the finished refrigerators) include: ABS resin (HTSUS 3903.30), fittings...

  14. Pump Jet Mixing and Pipeline Transfer Assessment for High-Activity Radioactive Wastes in Hanford Tank 241-AZ-102

    SciTech Connect

    Onishi, Yasuo; Recknagle, Kurtis P.; Wells, Beric E.

    2000-08-09

    This report evaluates how two 300-hp mixer pumps would mix solid and liquid radioactive wastes stored in Hanford double-shell Tank 241-AZ-102. It also assesses and confirms the adequacy of a 3-inch pipeline to transfer the resulting mixed waste slurry to the AP Tank Farm and ultimately to a planned waste treatment/vitrification plant on the Hanford Site.

  15. Effect of TiN nano-coating on the interface microstructure of carbon fibres-AZ91 alloy composite

    NASA Astrophysics Data System (ADS)

    Olszwka-Myalska, A.; Botor-Probierz, A.

    2012-03-01

    Magnesium matrix composites reinforced with carbon fibres, Cf, without surface modification and coated with TiN nanolayer, (Cf)TiN, were investigated. AZ91 magnesium alloy and carbon fibres of T300B (Toray) PAN type were chosen as components. In the experiment infiltration in vacuum as a method of component consolidation and chemical vapour deposition (CVD) for carbon fibres surface modification were applied. Structural investigations were performed in the Hitachi 3200S field-emission scanning electron microscope (FE-SEM) and on a FEI Tecnai G2 FEG high-resolution transmission electron microscope (TEM) equipped with energy-dispersive X-ray spectrometer (EDS) and high angle annular dark field (HAADF) detectors. SEM observations revealed that at the interface of AZ91-Cf composite destructive phases were formed. An application of TiN nano-coating as a surface modification ensured proper wettability of carbon fibres by liquid metal and protection against the destructive products formation. The microstructure of AZ91-(Cf)TiN composite interface was multilayered. TEM investigation revealed a continuous layer of mixed alumina and magnesia just at the carbon surface, followed by a layer with a dominant concentration of titanium, enriched with Al, O, Mg and C and subsequently a layer of nano-sized Al12Mg17 crystals in the magnesium matrix. Therefore, an applied TiN nano-coating can be classified as an active barrier in AZ91-Cf system.

  16. 76 FR 51462 - Notice of Release of an Easement Restriction at Phoenix-Mesa Gateway Airport, Mesa, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-18

    ... TRANSPORTATION Federal Aviation Administration Notice of Release of an Easement Restriction at Phoenix-Mesa Gateway Airport, Mesa, AZ AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of Request to... acres of property abutting Phoenix-Mesa Gateway, Mesa, Arizona, from all conditions contained in a...

  17. 14 CFR Special Federal Aviation... - 2-Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... the Grand Canyon National Park, AZ Federal Special Federal Aviation Regulation No. 50 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Pt. 91, SFAR No. 50-2 Special Federal Aviation...

  18. 14 CFR Special Federal Aviation... - 2-Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... the Grand Canyon National Park, AZ Federal Special Federal Aviation Regulation No. 50 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Pt. 91, SFAR No. 50-2 Special Federal Aviation...

  19. 14 CFR Special Federal Aviation... - 2-Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... the Grand Canyon National Park, AZ Federal Special Federal Aviation Regulation No. 50 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Pt. 91, SFAR No. 50-2 Special Federal Aviation...

  20. 14 CFR Special Federal Aviation... - 2-Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the Grand Canyon National Park, AZ Federal Special Federal Aviation Regulation No. 50 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Pt. 91, SFAR No. 50-2 Special Federal Aviation...

  1. 14 CFR Special Federal Aviation... - 2-Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the Grand Canyon National Park, AZ Federal Special Federal Aviation Regulation No. 50 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Pt. 91, SFAR No. 50-2 Special Federal Aviation...

  2. ARSENIC REMOVAL FROM DRINKING WATER BY ADSORPTIVE MEDIA. USEPA DEMONSTRATION PROJECT AT VALLEY VISTA, AZ FINAL PERFORMANCE EVALUATION REPORT

    EPA Science Inventory

    This report documents the activities performed during and the results obtained from the arsenic removal treatment technology demonstration project at an Arizona Water Company (AWC) facility in Sedona, AZ, commonly referred to as Valley Vista. The objectives of the project were t...

  3. VizieR Online Data Catalog: AzTEC survey of the SHADES fields. I. (Austermann+, 2010)

    NASA Astrophysics Data System (ADS)

    Austermann, J. E.; Dunlop, J. S.; Perera, T. A.; Scott, K. S.; Wilson, G. W.; Aretxaga, I.; Hughes, D. H.; Almaini, O.; Chapin, E. L.; Chapman, S. C.; Cirasuolo, M.; Clements, D. L.; Coppin, K. E. K.; Dunne, L.; Dye, S.; Eales, S. A.; Egami, E.; Farrah, D.; Ferrusca, D.; Flynn, S.; Haig, D.; Halpern, M.; Ibar, E.; Ivison, R. J.; van Kampen, E.; Kang, Y.; Kim, S.; Lacey, C.; Lowenthal, J. D.; Mauskopf, P. D.; McLure, R. J.; Mortier, A. M. J.; Negrello, M.; Oliver, S.; Peacock, J. A.; Pope, A.; Rawlings, S.; Rieke, G.; Roseboom, I.; Rowan-Robinson, M.; Scott, D.; Serjeant, S.; Smail, I.; Swinbank, A. M.; Stevens, J. A.; Velazquez, M.; Wagg, J.; Yun, M. S.

    2012-01-01

    We have completed the SHADES (Mortier et al., 2005, Cat. J/MNRAS/363/563) by mapping over one-half square degree of sky using the AzTEC 1.1-mm camera mounted on the 15-m James Clerk Maxwell Telescope (JCMT). (3 data files).

  4. Weldability of A7075-T651 and AZ31B dissimilar alloys by MIG welding method based on welding appearances

    NASA Astrophysics Data System (ADS)

    Ishak, M.; Islam, M. R.

    2014-04-01

    It is not recommended to weld aluminium and magnesium dissimilar alloys using fusion welding method because of the formation of AlmMgn type intermetallic brittle compounds like Mg2Al3, Mg17Al12 etc. in the welding joint. These brittle compounds deteriorate the mechanical properties of the joint. But so far, insufficient researches have been attempted to stop the formation of AlmMgn type intermetallic brittle compounds in fusion welding method. The aim of this research work was to investigate on the weldability between A7075-T651 and AZ31B dissimilar alloys based on welding appearances and study the formation of intermetallic brittle compounds at the joint. In this research, A7075-T651 and AZ31B alloys were welded using ER5356 filler wire in MIG welding method in butt configuration. 100% argon was used as shielding gas. The results showed that, most of the welding appearances were moderate. The macroscopic investigation at all welding cross section showed that a lot of AlmMgn intermetallic brittle compounds were formed at the interface between weld seam and AZ31B parent metal side which caused macro cracks. A good number of macro pores were also observed at AZ31B parent metal side. These cracks and pores could easily cause the failure of the joint at very low stress.

  5. 14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES Special Flight Rules...

  6. ARSENIC REMOVAL FROM DRINKING WATER BY ADSORPTIVE MEDIA, USEPA DEMONSTRATION PROJECT AT RIMROCK, AZ, SIX-MONTH EVALUATION REPORT

    EPA Science Inventory

    This report documents the activities performed during and the results obtained from the first six months of the arsenic removal treatment technology demonstration project at Rimrock, AZ. The objectives of the project are to evaluate the effectiveness of AdEdge Arsenic Package Uni...

  7. Arsenic Removal from Drinking Water by Adsorptive Media USEPA Demonstration Project at Rimrock AZ Final Performance Evaluation Report

    EPA Science Inventory

    This report documents the activities performed during and the results obtained from the arsenic removal treatment technology demonstration project at the Arizona Water Company (AWC) facility in Rimrock, AZ. The objectives of the project were to evaluate: 1) the effectiveness of ...

  8. 78 FR 53477 - Notice of Relocation of the Bureau of Land Management's San Pedro Project Office in Sierra Vista, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-29

    ... Bureau of Land Management Notice of Relocation of the Bureau of Land Management's San Pedro Project Office in Sierra Vista, AZ AGENCY: Bureau of Land Management, Interior. ACTION: Notice. SUMMARY: This notice announces the relocation of the Bureau of Land Management's (BLM) San Pedro Project Office...

  9. Discriminating nucleosomes containing histone H2A.Z or H2A based on genetic and epigenetic information

    PubMed Central

    Gervais, Alain L; Gaudreau, Luc

    2009-01-01

    Background Nucleosomes are nucleoproteic complexes, formed of eight histone molecules and DNA, and they are responsible for the compaction of the eukaryotic genome. Their presence on DNA influences many cellular processes, such as transcription, DNA replication, and DNA repair. The evolutionarily conserved histone variant H2A.Z alters nucleosome stability and is highly enriched at gene promoters. Its localization to specific genomic loci in human cells is presumed to depend either on the underlying DNA sequence or on a certain epigenetic modification pattern. Results We analyzed the differences in histone post-translational modifications and DNA sequences near nucleosomes that do or do not contain H2A.Z. We show that both the epigenetic context and underlying sequences can be used to classify nucleosomal regions, with highly significant accuracy, as likely to either contain H2A.Z or canonical histone H2A. Furthermore, our models accurately recapitulate the observed nucleosome occupancy near the transcriptional start sites of human promoters. Conclusion We conclude that both genetic and epigenetic features are likely to participate in targeting H2A.Z to distinct chromatin loci. PMID:19261190

  10. 78 FR 34403 - Notice of Availability of the Record of Decision for the Quartzsite Solar Energy Project, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-07

    ... Plan (RMP) for the Quartzsite Solar Energy Project (QSEP). The Acting Assistant Secretary for Land and...) at the following Web site: http://www.blm.gov/az/st/en/prog/energy/solar/quartzsite_solar_energy.html...: Quartzsite Solar Energy LLC, a subsidiary of Solar Reserve LLC, proposes to build the QSEP, a...

  11. Pump Jet Mixing and Pipeline Transfer Assessment for High-Activity Radioactive Wastes in Hanford Tank 241-AZ-102

    SciTech Connect

    Y Onishi; KP Recknagle; BE Wells

    2000-08-09

    The authors evaluated how well two 300-hp mixer pumps would mix solid and liquid radioactive wastes stored in Hanford double-shell Tank 241-AZ-102 (AZ-102) and confirmed the adequacy of a three-inch (7.6-cm) pipeline system to transfer the resulting mixed waste slurry to the AP Tank Farm and a planned waste treatment (vitrification) plant on the Hanford Site. Tank AZ-102 contains 854,000 gallons (3,230 m{sup 3}) of supernatant liquid and 95,000 gallons (360 m{sup 3}) of sludge made up of aging waste (or neutralized current acid waste). The study comprises three assessments: waste chemistry, pump jet mixing, and pipeline transfer. The waste chemical modeling assessment indicates that the sludge, consisting of the solids and interstitial solution, and the supernatant liquid are basically in an equilibrium condition. Thus, pump jet mixing would not cause much solids precipitation and dissolution, only 1.5% or less of the total AZ-102 sludge. The pump jet mixing modeling indicates that two 300-hp mixer pumps would mobilize up to about 23 ft (7.0 m) of the sludge nearest the pump but would not erode the waste within seven inches (0.18 m) of the tank bottom. This results in about half of the sludge being uniformly mixed in the tank and the other half being unmixed (not eroded) at the tank bottom.

  12. Warm Deep Drawing of Rectangular Parts of AZ31 Magnesium Alloy Sheet Adopting Variable Blank Holder Force

    SciTech Connect

    Peng Yinghong; Chang Qunfeng; Li Dayong; Zeng Xiaoqin

    2007-05-17

    AZ31 magnesium alloy sheet with good shape and formability is fabricated by warm cross rolling. Uniaxial tensile tests are conducted using a Gleeble 3500 thermal - mechanical simulator, and the mechanical properties of AZ31 magnesium alloy sheet are analyzed. A warm deep drawing process of square part is also simulated by the finite element method. The influences of blank holder force on the formability are numerically investigated. A double-action hydraulic press that can realize adjustable blank holder forces is developed and its working principle and control system are introduced. Some warm deep drawing experiments of square parts of AZ31 magnesium alloy sheet are also performed. Different variation schemes of the blank holder force with the stroke of the punch are tested, and the experiment results are compared. Results show that the suitable blank holder force variation scheme is a ladder curve with the punch stroke. Adopting the variable blank holder force technique can improve 13.2% of the drawing depth of square parts of AZ31 magnesium alloy sheet.

  13. The Sustainable City.

    ERIC Educational Resources Information Center

    Gangloff, Deborah

    1995-01-01

    Focuses on methods to make cities more sustainable through the processes of energy efficiency, pollution and waste reduction, capture of natural processes, and the merger of ecological, economic, and social factors. (LZ)

  14. City sewer collectors biocorrosion

    NASA Astrophysics Data System (ADS)

    Ksiaż ek, Mariusz

    2014-12-01

    This paper presents the biocorrosion of city sewer collectors impregnated with special polymer sulphur binders, polymerized sulphur, which is applied as the industrial waste material. The city sewer collectors are settled with a colony of soil bacteria which have corrosive effects on its structure. Chemoautotrophic nitrifying bacteria utilize the residues of halites (carbamide) which migrate in the city sewer collectors, due to the damaged dampproofing of the roadway and produce nitrogen salts. Chemoorganotrophic bacteria utilize the traces of organic substrates and produce a number of organic acids (formic, acetic, propionic, citric, oxalic and other). The activity of microorganisms so enables the origination of primary and secondary salts which affect physical properties of concretes in city sewer collectors unfavourably.

  15. Development and validation of the Pediatric AzBio sentence lists

    PubMed Central

    Spahr, Anthony J.; Dorman, Michael F.; Litvak, Leonid M.; Cook, Sarah; Loiselle, Louise M.; DeJong, Melissa D.; Hedley-Williams, Andrea; Sunderhaus, Linsey S.; Hayes, Catherine A.; Gifford, Ren H.

    2014-01-01

    Objectives The goal of this study was to create and validate a new set of sentence lists that could be used to evaluate the speech perception abilities of listeners with hearing loss in cases where adult materials are inappropriate due to difficulty level or content. Our intention was to generate a large number of sentence lists with an equivalent level of difficulty for the evaluation of performance over time and across conditions. Design The original Pediatric-AzBio sentence corpus included 450 sentences recorded from one female talker. All sentences included in the corpus were successfully repeated by kindergarten and first grade students with normal hearing. The mean intelligibility of each sentence was estimated by processing each sentence through a cochlear implant simulation and calculating the mean percent correct score achieved by 15 normal-hearing listeners. After sorting sentences by mean percent correct scores, 320 sentences were assigned to 16 lists of equivalent difficulty. List equivalency was then validated by presenting all sentence lists, in a novel random order, to adults and children with hearing loss. A final-validation stage examined single-list comparisons from adult and pediatric listeners tested in research or clinical settings. Results The results of the simulation study allowed for the creation of 16 lists of 20 sentences. The average intelligibility of each list ranged from 78.4% to 78.7%. List equivalency was then validated, when the results of 16 adult cochlear implant users and 9 pediatric hearing aid and cochlear implant users revealed no significant differences across lists. The binomial distribution model was used to account for the inherent variability observed in the lists. This model was also used to generate 95% confidence intervals for one and two list comparisons. A retrospective analysis of 361 instances from 78 adult cochlear implant users and 48 instances from 36 pediatric cochlear implant users revealed that the 95% confidence intervals derived from the model captured 94% of all responses (385/409). Conclusions The cochlear implant simulation was shown to be an effective method for estimating the intelligibility of individual sentences for use in the evaluation of cochlear implant users. Further the method used for constructing equivalent sentence lists and estimating the inherent variability of the materials has also been validated. Thus, the AzBio Pediatric Sentence Lists are equivalent and appropriate for the assessment of speech understanding abilities of children with hearing loss as well as adults for whom performance on AzBio sentences is near the floor. PMID:24658601

  16. AZ-101 Mixer Pump Demonstration and Tests Data Management Analysis Plan

    SciTech Connect

    DOUGLAS, D.G.

    2000-02-22

    This document provides a plan for the analysis of the data collected during the AZ-101 Mixer Pump Demonstration and Tests. This document was prepared after a review of the AZ-101 Mixer Pump Test Plan (Revision 4) [1] and other materials. The plan emphasizes a structured and well-ordered approach towards handling and examining the data. This plan presumes that the data will be collected and organized into a unified body of data, well annotated and bearing the date and time of each record. The analysis of this data will follow a methodical series of steps that are focused on well-defined objectives. Section 2 of this plan describes how the data analysis will proceed from the real-time monitoring of some of the key sensor data to the final analysis of the three-dimensional distribution of suspended solids. This section also identifies the various sensors or sensor systems and associates them with the various functions they serve during the test program. Section 3 provides an overview of the objectives of the AZ-101 test program and describes the data that will be analyzed to support that test. The objectives are: (1) to demonstrate that the mixer pumps can be operated within the operating requirements; (2) to demonstrate that the mixer pumps can mobilize the sludge in sufficient quantities to provide feed to the private contractor facility, and (3) to determine if the in-tank instrumentation is sufficient to monitor sludge mobilization and mixer pump operation. Section 3 also describes the interim analysis that organizes the data during the test, so the analysis can be more readily accomplished. Section 4 describes the spatial orientation of the various sensors in the tank. This section is useful in visualizing the relationship of the Sensors in terms of their location in the tank and how the data from these sensors may be related to the data from other sensors. Section 5 provides a summary of the various analyses that will be performed on the data during the test program. Finally, an appendix reviews the technical aspects of the key sensor systems that will be used in the program. This review focuses on the performance capabilities and limits of the sensing systems.

  17. Effect of microalloying on microstructure and hot working behavior for AZ31 based magnesium alloy

    NASA Astrophysics Data System (ADS)

    Shang, Lihong

    The formability of Mg alloy sheet in the as-hot rolled condition depends on the microstructure developed during hot rolling. In general, the formability of Mg alloys is improved by finer grain sizes. 'Microalloying' levels of calcium (Ca), strontium (Sr), and cerium (Ce) have been found to refine the as-cast structure, but there is no information as to whether this effect will be reflected in the as-hot worked structure and formability. Thus, in this work, the effects of microalloying levels of calcium (Ca), strontium (Sr), and cerium (Ce) on the microstructures (from as-cast to as-hot rolled) and subsequent hot deformation behavior of AZ31, nominally 3% Al, 1% Zn, and 0.3%Mn, were systematically investigated. To include the effect of solidification rate these alloys were cast in different moulds (preheated steel mould, Cu-mould, and water cooled Cu-mould). One-hit compression testing at temperatures between 250C 400 C, strain rates of 0.001, 0.01, 0.1 s-1 and strains from 0.2 up to 1.0, was performed to investigate the basic hot compression behavior, while two-hit compression testing was conducted to determine the static softening behavior. Hot rolling of the microalloyed AZ31 alloys was then carried out to study the effects of microalloying on as-hot rolled structure under two sets of rolling schedules. To investigate the formability of these microalloyed sheets, tensile tests were completed over a temperature range between ambient and 450C, at strain rates between 0.1 and 0.0003 s-1. Results show that Ca and Sr act to refine the as cast grain size and the second phases, consistently promoting fine and uniform as-hot rolled grain structure. With regard to grain refinement, calcium has the strongest effect, whereas Ce is most effective for second phase refinement. In addition, microalloying retards grain growth during hot tensile testing. Multiple alloying presents a combined and complementary effect. A refined and uniform grain structure combined with well dispersed and thermally stable second phases significantly improves the hot formability of AZ31 sheets by promoting dynamic recrystallization (DRX) in the matrix, resisting grain coarsening, and retarding the development of cavitation and necking. Under the superplastic condition of 450C and 0.0003 s -1, the elongation was improved by 17% with Ca only, 26% with Ca and Ce, 51% with Ca and Sr, and 59% with Ca, Sr and Ce.

  18. Systematic understanding of corrosion behavior of plasma electrolytic oxidation treated AZ31 magnesium alloy using a mouse model of subcutaneous implant.

    PubMed

    Jang, Yongseok; Tan, Zongqing; Jurey, Chris; Collins, Boyce; Badve, Aditya; Dong, Zhongyun; Park, Chanhee; Kim, Cheol Sang; Sankar, Jagannathan; Yun, Yeoheung

    2014-12-01

    This study was conducted to identify the differences between corrosion rates, corrosion types, and corrosion products in different physiological environments for AZ31 magnesium alloy and plasma electrolytic oxidation (PEO) treated AZ31 magnesium alloy. In vitro and in vivo tests were performed in Hank's Balanced Salt Solution (HBSS) and mice for 12 weeks, respectively. The corrosion rates of both AZ31 magnesium alloy and PEO treated AZ31 magnesium alloy were calculated based on DC polarization curves, volume of hydrogen evolution, and the thickness of corrosion products formed on the surface. Micro X-ray computed tomography (Micro-CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) were used to analyze morphological and chemical characterizations of corrosion products. The results show that there is more severe localized corrosion after in vitro test in HBSS; however, the thicknesses of corrosion products formed on the surface for AZ31 magnesium alloy and PEO treated AZ31 magnesium alloy in vivo were about 40% thicker than the thickness of corrosion products generated in vitro. The ratio of Ca and P (Ca/P) in the corrosion products also differed. The Ca deficient region and higher content of Al in corrosion product than AZ31 magnesium alloy were identified after in vivo test in contrast with the result of in vitro test. PMID:25491800

  19. Sinking coastal cities

    NASA Astrophysics Data System (ADS)

    Erkens, G.; Bucx, T.; Dam, R.; de Lange, G.; Lambert, J.

    2015-11-01

    In many coastal and delta cities land subsidence now exceeds absolute sea level rise up to a factor of ten. A major cause for severe land subsidence is excessive groundwater extraction related to rapid urbanization and population growth. Without action, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other coastal cities will sink below sea level. Land subsidence increases flood vulnerability (frequency, inundation depth and duration of floods), with floods causing major economic damage and loss of lives. In addition, differential land movement causes significant economic losses in the form of structural damage and high maintenance costs for (infra)structure. The total damage worldwide is estimated at billions of dollars annually. As subsidence is often spatially variable and can be caused by multiple processes, an assessment of subsidence in delta cities needs to answer questions such as: what are the main causes? What is the current subsidence rate and what are future scenarios (and interaction with other major environmental issues)? Where are the vulnerable areas? What are the impacts and risks? How can adverse impacts be mitigated or compensated for? Who is involved and responsible to act? In this study a quick-assessment of subsidence is performed on the following mega-cities: Jakarta, Ho Chi Minh City, Dhaka, New Orleans and Bangkok. Results of these case studies will be presented and compared, and a (generic) approach how to deal with subsidence in current and future subsidence-prone areas is provided.

  20. Fabrication of microfluidic chips using lithographic patterning and adhesive bonding of the thick negative photoresist AZ 125 nXT

    NASA Astrophysics Data System (ADS)

    Knoll, Thorsten; Bergmann, Andreas; Nußbaum, Dominic

    2015-05-01

    In this work, for the first time the negative photoresist AZ 125 nXT was used for the fabrication of a microfluidic chip. Usually, fabrication of microfluidic devices on the basis of silicon or glass substrates is done by using the epoxy-based negative photoresist SU-8 or other thick film polymer materials. The suitability of SU-8 for various microfluidic applications has been shown in the fields of bioanalytic devices, lab-on-chip systems or microreaction technology. However, processing is always a very challenging task with regard to the adaptation of process parameters to the individual design and required functionality. Now, the AZ 125 nXT allows for the fabrication of structures in a wide thickness range with only one type of viscosity. In contrast to SU-8, the AZ 125 nXT is fully cross-linked during UV exposure and does not require a time-consuming post-exposure bake. 90 μm deep microfluidic channels were defined by lithographic patterning of AZ 125 nXT. Sealing of the open microfluidic channels was performed by a manual adhesive bonding process at a temperature of 100 °C. The fluidic function was successfully tested with flow rates up to 20 ml/min by means of a microfluidic edge connector. Long term stability and chemical resistance of the fabricated microfluidic channels will be investigated in the near future. The presented work shows the potential of AZ 125 nXT as a possible alternative to SU-8 for the fabrication of microfluidic chips.

  1. Learning Cities on the Move

    ERIC Educational Resources Information Center

    Kearns, Peter

    2015-01-01

    The modern Learning City concept emerged from the work of OECD on lifelong learning with streams of Learning Cities and Educating Cities having much in common but having little contact with each other. While the early development of Learning Cities in the West has not been sustained, the present situation is marked by the dynamic development of

  2. City Lights: America's Boldest Mayors.

    ERIC Educational Resources Information Center

    Eggers, William D.

    1993-01-01

    Although the plight of cities seems nearly hopeless, three new-style big city mayors have emerged to try ideas deserving study by other cities. Edward Rendell of Philadelphia (Pennsylvania), John Norquist of Milwaukee (Wisconsin), and Stephen Goldsmith of Indianapolis (Indiana) are demonstrating that U.S. cities can be made to work. (SLD)

  3. Evaluation of cracking in the 241-AZ tank farm ventilation line at the Hanford Site

    SciTech Connect

    ANANTATMULA, R.P.

    1999-10-20

    In the period from April to October of 1988, a series of welding operations on the outside of the AZ Tank Farm ventilation line piping at the Hanford Site produced unexpected and repeated cracking of the austenitic stainless steel base metal and of a seam weld in the pipe. The ventilation line is fabricated from type 304L stainless steel pipe of 24 inch diameter and 0.25 inch wall thickness. The pipe was wrapped in polyethylene bubble wrap and buried approximately 12 feet below grade. Except for the time period between 1980 and 1987, impressed current cathodic protection has been applied to the pipe since its installation in 1974. The paper describes the history of the cracking of the pipe, the probable cracking mechanisms, and the recommended future action for repair/replacement of the pipe.

  4. Formation Mechanism of Discoloration on Die-Cast AZ91D Components Surface After Chemical Conversion

    NASA Astrophysics Data System (ADS)

    Liu, Bao-sheng; Wei, Ying-hui; Hou, Li-feng

    2013-01-01

    A notebook (NB) computer component was manufactured from AZ91D Mg alloy by a die-casting process. After chemical conversion treatment, a discoloration was noted on the component surface. The source of this discoloration has been studied in detail by scanning electron microscopy, energy dispersive spectroscopy, and spark atomic absorption spectroscopy. The corrosion resistance was also measured by potentiodynamic polarization, hydrogen evolution and salt spray testing. The formation mechanism for the discoloration which was caused by the residue left behind by excess mold release agent sprayed during the die-casting was discussed in detail. After chemical conversion treatment, the residual-baked mold release agent was apparent on the component surface as "white ash." Consequently, it degraded seriously both the appearance and the corrosion resistance of the manufactured component.

  5. AZ-101 Mixer Pump Test MT Fury Suspended Solids Profiler Application and Testing

    SciTech Connect

    MACLEAN, G.T.

    2000-01-06

    Describes the radiation testing and calibration of the AZ-101 tank suspended solids profiler unit mounted on 6 tank riser 24A. The Mt. Fury Suspended Solids Profiler (SSP) is a microprocessor-controlled instrument that measures the turbidity of solid-liquid suspensions and sludges. The profiler is used commercially for the monitoring and control of clarifiers and thickeners in waste treatment, mining, pulp and paper, and other industrial processing facilities. The instrument includes a three inch diameter probe, a Kynar coated coaxial cable, a reel assembly with a clutch and drive shaft, a stepper motor, and electronics. The instrument measures insoluble or suspended solids content in liquids by transmitting infrared energy at a wavelength of 935 nm and measuring the extent of backscatter. This frequency is not affected by solution color. There are two detectors that allow the instrument to operate over a broad range of concentrations, from clear liquids to light sludges.

  6. Warm Deep Drawing Of Rectangular Cups With Magnesium Alloy AZ31 Sheets

    NASA Astrophysics Data System (ADS)

    Ren, L. M.; Palumbo, G.; Zhang, S. H.; Tricarico, L.

    2007-05-01

    Recently, magnesium alloys have been widely applied in automotive and electronic industries as the lightest weight structural and functional materials. Warm forming of magnesium alloys has attracted much attention due to the very poor formability of Mg alloys at room temperature. The formability of magnesium alloy sheet at elevated temperature is significantly affected by the processing parameters. Among them the forming temperature, the punch speed, the geometrical shape of the blank, the blank holder force and the lubrication are probably the most relevant. In this research, the deep drawing of rectangular cups with AZ31 sheets was conducted at elevated temperatures with different process parameters. The finite element analyses were performed to investigate the effects of the process parameters on the formability of rectangular cup drawing and to predict the process defects during the process. The material yield condition was modeled using the isotropic Von Mises criterion. The flow stress data were obtained from tensile tests.

  7. Laser surface structuring of AZ31 Mg alloy for controlled wettability.

    PubMed

    Gkhan Demir, Ali; Furlan, Valentina; Lecis, Nora; Previtali, Barbara

    2014-06-01

    Structured surfaces exhibit functional properties that can enhance the performance of a bioimplant in terms of biocompatibility, adhesion, or corrosion behavior. In order to tailor the surface property, chemical and physical methods can be used in a sequence of many steps. On the other hand, laser surface processing can provide a single step solution to achieve the designated surface function with the use of simpler equipment and high repeatability. This work provides the details on the surface structuring of AZ31, a biocompatible and biodegradable Mg alloy, by a single-step laser surface structuring based on remelting. The surfaces are characterized in terms of topography, chemistry, and physical integrity, as well as the effective change in the surface wetting behavior is demonstrated. The results imply a great potential in local or complete surface structuring of medical implants for functionalization by the flexible positioning of the laser beam. PMID:24985213

  8. Cyclic Plasticity Constitutive Model for Uniaxial Ratcheting Behavior of AZ31B Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Lin, Y. C.; Liu, Zheng-Hua; Chen, Xiao-Min; Long, Zhi-Li

    2015-05-01

    Investigating the ratcheting behavior of magnesium alloys is significant for the structure's reliable design. The uniaxial ratcheting behavior of AZ31B magnesium alloy is studied by the asymmetric cyclic stress-controlled experiments at room temperature. A modified kinematic hardening model is established to describe the uniaxial ratcheting behavior of the studied alloy. In the modified model, the material parameter m i is improved as an exponential function of the maximum equivalent stress. The modified model can be used to predict the ratcheting strain evolution of the studied alloy under the single-step and multi-step asymmetric stress-controlled cyclic loadings. Additionally, due to the significant effect of twinning on the plastic deformation of magnesium alloy, the relationship between the material parameter m i and the linear density of twins is discussed. It is found that there is a linear relationship between the material parameter m i and the linear density of twins induced by the cyclic loadings.

  9. Characterization of Al-Mn particles in AZ91D investment castings

    SciTech Connect

    Lun Sin, S.; Dube, D. Tremblay, R.

    2007-10-15

    Manganese is currently added to Mg-Al alloys in order to improve the corrosion behavior of cast components. A part of this manganese is dissolved in the magnesium matrix and the balance is found as fine Al(Mn,Fe) particles dispersed within castings. For AZ91D specimens prepared using the plaster mould investment casting process, these particles were observed in very large quantity at the surface of castings. These particles were characterized by scanning electron microscopy and electron probe microanalysis. It was found that they consist of Al{sub 8}Mn{sub 5} phase and that their morphology and size depend on local solidification conditions. Their presence at the surface of the castings is related to low solidification rates and reduced thermal gradients at the mould/metal interface.

  10. Grain Refinement of AZ31 Magnesium Alloy Weldments by AC Pulsing Technique

    NASA Astrophysics Data System (ADS)

    Kishore Babu, N.; Cross, C. E.

    2012-11-01

    The current study has investigated the influence of alternating current pulsing on the structure and mechanical properties of AZ31 magnesium alloy gas tungsten arc (GTA) weldments. Autogenous full penetration bead-on-plate GTA welds were made under a variety of conditions including variable polarity (VP), variable polarity mixed (VPM), alternating current (AC), and alternating current pulsing (ACPC). AC pulsing resulted in significant refinement of weld metal when compared with the unpulsed conditions. AC pulsing leads to relatively finer and more equiaxed grain structure in GTA welds. In contrast, VP, VPM, and AC welding resulted in predominantly columnar grain structures. The reason for this grain refinement may be attributed to the periodic variations in temperature gradient and solidification rate associated with pulsing as well as weld pool oscillation observed in the ACPC welds. The observed grain refinement was shown to result in an appreciable increase in fusion zone hardness, tensile strength, and ductility.

  11. Tank 241-AZ-101 prototype corrosion probe four month status report

    SciTech Connect

    Edgemon, G.L., Westinghouse Hanford

    1996-12-12

    High-level nuclear wastes at the Hanford Site are stored underground in carbon steel double-shell and single-shell tanks. The installation of a prototype corrosion monitoring system into double-shell tank 241-AZ-101 was completed in August, 1996. The system monitors fluctuations in corrosion current and potential (electrochemical noise) occurring on three electrode arrays immersed in the waste liquid and in the vapor space above the waste. The system also supports the use of Tafel and linear polarization resistance testing. By monitoring and analyzing the data from these techniques, changes in the corrosive characteristics of the waste have been rapidly detected and correlated with operational changes in the tank.

  12. Tribological properties of heat-treated electroless Ni-P coatings on AZ91 alloy

    NASA Astrophysics Data System (ADS)

    Novk, M.; Vojt?ch, D.; Novk, P.; Vt?, T.

    2011-09-01

    Influence of heat treatment regime on adhesion and wear resistance of Ni-P electroless coating on AZ91 magnesium alloy is investigated in this work. The pretreated substrate was plated using a bath containing nickel sulphate, sodium hypophosphite and sodium acetate as main constituents. The coated samples were heat treated at 400-450 C for 1-8 h. Adhesion of coating was estimated from the scratch test with an initial load of 8.80 N. Wear resistance was studied using the pin-on-disc method. It was found that there is no significant dependence of the coating wear resistance on heat treatment regime, as the formation of Al-Ni intermetallic sub-layers that reduce coating adhesion is limited to regions where Al17Mg12 phase is present in the substrate. Moreover, the coating shows good sliding properties due to the formation of oxide glazes in the wear track.

  13. A cellular automaton model for dendrite growth in magnesium alloy AZ91

    NASA Astrophysics Data System (ADS)

    Yin, Hebi; Felicelli, Sergio D.

    2009-10-01

    A coupled cellular automaton (CA)-finite element (FE) model was developed to calculate dendrite growth during the solidification of hexagonal metals. The model solved the conservation equations of mass, energy and solutes in order to calculate the temperature field, solute concentration and the dendritic growth morphology. Validation of the model was performed by comparing the simulation results with experimental and computational data from previously published works, showing qualitatively good agreement in the dendritic morphology. Application to magnesium alloy AZ91 (approximated with the binary Mg-8.9 wt%Al) illustrates the difficulty of modeling dendrite growth in hexagonal systems, observed as deviations in the growth direction caused by mesh-induced anisotropy. The model was applied to the simulation of small specimens with equiaxed grain growth and columnar grain growth in directional solidification. The influences of cooling rate, mesh size and kinetic parameters such as surface tension and anisotropy coefficient on the grain morphology were also discussed.

  14. Nd:YAG Laser Welding of AZ91 Magnesium Alloy for Aerospace Industries

    NASA Astrophysics Data System (ADS)

    Abderrazak, Kamel; Ben Salem, Wacef; Mhiri, Hatem; Bournot, Philippe; Autric, Michel

    2009-02-01

    Magnesium alloys have attracted the interest of the modern manufacturing industry owing to their higher strength-to-weight ratios and heat conductivity than other alloys. Laser welding will be an important joining technique for magnesium alloys with their increasing applications in aerospace, aircraft, automotive, electronics, and other industries. The Nd:YAG laser beam has the reputation to be a rapid, precise, and easy process for welding of magnesium alloys. In this study, the use of an Nd:YAG laser for thin-plate AZ91 magnesium alloy welding was optimized. The welding cross section geometries were determined by optical microscopy analysis. Some important laser processing parameters (laser power, welding speed, and shielding gas flow) and their effects on the welding quality are discussed.

  15. Investigation of interfacial interaction between uncoated and coated carbon fibres and the magnesium alloy AZ91.

    PubMed

    Dorner-Reisel, A; Nishida, Y; Klemm, V; Nestler, K; Marx, G; Mller, E

    2002-10-01

    Unidirectionally reinforced metal-matrix composites with a fibre volume content between 63 and 68% were processed by squeeze casting using T800 H carbon fibres and the magnesium alloy AZ91. The surface of the fibres was prepared by thermal desizing of the fibres or by deposition of a pyrolytic carbon (pyC) coating. Different interfacial conditions could be identified by transmission electron microscopy (TEM) and the single-fibre push-in test. TEM confirmed the formation of needle-like phases at the fibre surface or, for coated fibres, within the pyrolytic carbon coating. During loading by the Vickers type indenter an intense response was observed for composites of coated fibres and the magnesium alloy. This could by caused by stick-slip effects within the pyrolytic carbon coating. PMID:12397483

  16. Low temperature superplasticity of AZ91 magnesium alloy with non-equilibrium grain boundaries

    SciTech Connect

    Mabuchi, M.; Ameyama, K.; Iwasaki, H.; Higashi, K.

    1999-05-28

    The superplastic behavior of a fine-grained AZ91 alloy, processed by equal channel angular extrusion, has been investigated in a low temperature range of 423--523 K. The experimental results showed a stress exponent of 2 and the activation energy for superplastic flow was in agreement with that for grain boundary diffusion of magnesium. The alloy with non-equilibrium grain boundary structures exhibited lower superplastic elongation than the alloy with equilibrium grain boundaries. Furthermore, the strain rate for superplastic flow of the former was lower than that of the latter. These differences probably arise because the accommodation process for grain boundary sliding is hampered by the long-range stresses associated with the non-equilibrium grain boundaries.

  17. Initiation of fatigue cracks in AZ91 Mg alloy processed by ECAP

    NASA Astrophysics Data System (ADS)

    Fintov, S.; Kunz, L.

    2014-08-01

    Mechanism of fatigue crack initiation was investigated in ultrafine-grained (UFG) magnesium alloy AZ91 processed by equal channel angular pressing (ECAP). Fatigue behaviour of UFG material was compared to the behaviour of material in an initial as-cast state. Focused ion beam technique (FIB) was applied to reveal the surface relief and early fatigue cracks. Two substantially different mechanisms of crack initiation were observed in UFG structure, which can be characterized as bimodal even after 6 ECAP passes by route Bc. The bimodality consists in a coexistence of very fine grained areas with higher content of Mg17Al12 particles and areas exhibiting somewhat larger grains and lower density of particles. The fatigue cracks which initiate in areas of larger grains are related to the cyclic slip bands; this initiation mechanism is similar to that observed in cast alloy. The second initiation mechanism is related to the grain boundary cracking which takes place predominantly in the fine grained areas.

  18. Effect of heat treatments on oxidation kinetics in AZ91 and AM60 magnesium alloys

    SciTech Connect

    Barrena, M.I. Gomez de Salazar, J.M.; Matesanz, L.; Soria, A.

    2011-10-15

    The effect of heat treatments on a non protective atmosphere (air) on the morphology and composition of the oxide in AM60 and AZ91 alloys has been evaluated. With the aim of evaluating the loss of alloying elements during heat treatment, a study of these alloys has been carried out using thermogravimetric analysis (TGA). In order to determine the nature of the oxides the reaction products generated were evaluated by scanning electron microscopy and X-ray diffraction. Results show that the nature and morphology of the oxides generated are related to the temperature and the time of the heating conditions applied. - Highlights: {yields} The effect of heat treatments on the oxide growth in Mg-Al alloys has been evaluated. {yields} The nature and morphology of the oxides have been characterized. {yields} These oxides are associated to the time and the temperature conditions.

  19. Biodegradation behavior of micro-arc oxidized AZ31 magnesium alloys formed in two different electrolytes

    NASA Astrophysics Data System (ADS)

    Seyfoori, A.; Mirdamadi, Sh.; Khavandi, A.; Raufi, Z. Seyed

    2012-11-01

    Degradation behavior of coated magnesium alloys is among most prominent factors for their biomedical applications. In this study, bio-corrosion behavior of micro-arc oxidized magnesium AZ31 alloys formed in silicate and phosphate baths was investigated in r-SBF medium. For this purpose polarization behavior and open circuit profile of the coated samples were achieved by electrochemical and immersion tests, respectively. Moreover, the morphology and composition of the coatings were evaluated before and after immersion test using scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. The results showed that the phosphate film had better corrosion resistance and greater thickness than silicate film and, in turn, the lesser degradability in SBF solution, so that Ca2+ and PO43- containing compounds were more abundant on silicate film than phosphate film. Moreover phosphate film had greater surface roughness and lesser hydrophilic nature.

  20. Simulation of cylindrical cup drawing of AZ31 sheet metal with crystal plasticity finite element method

    NASA Astrophysics Data System (ADS)

    Tang, Weiqin; Li, Dayong; Zhang, Shaorui; Peng, Yinghong

    2013-12-01

    As a light-weight structural material, magnesium alloys show good potential in improving the fuel efficiency of vehicles and reducing CO2 emissions. However, it is well known that polycrystalline Mg alloys develop pronounced crystallographic texture and plastic anisotropy during rolling, which leads to earing phenomenon during deep drawing of the rolled sheets. It is vital to predict this phenomenon accurately for application of magnesium sheet metals. In the present study, a crystal plasticity model for AZ31 magnesium alloy that incorporates both slip and twinning is established. Then the crystal plasticity model is implemented in the commercial finite element software ABAQUS/Explicit through secondary development interface (VUMAT). Finally, the stamping process of a cylindrical cup is simulated using the developed crystal plasticity finite element model, and the predicting method is verified by comparing with experimental results from both earing profile and deformation texture.

  1. Fiber laser cutting of AZ31 magnesium alloy: numerical and experimental investigation

    NASA Astrophysics Data System (ADS)

    Guo, Huafeng; Li, Juli; He, Min; Wu, Xiao; Sun, Tao

    2015-10-01

    Fiber laser cutting of AZ31B magnesium alloy is considered. A three-dimensional (3D) finite element model (FEM) for simulation of the transient temperature field in laser cutting process is developed. The FEM take into account of the thermal physical parameters change with temperature, the moving heat source, the surface effect element, the reasonable boundary conditions, etc. The temperature evolution, the temperature gradient, the kerf shape and dimensions are simulated. Kerf width are measured using the Olympus optical microscopy and is compared with the predicted value. The microhardness near the kerf is measured by a Vickers microhardness tester. The results show that the maximum temperature gradually increased with the increase of cutting time. The workpiece temperature rise to 135.72C from the room temperature. The simulated kerf width are in good agreement with measured results. The heat affected zone is not obvious and the microhardness change little perpendicular to laser cutting direction.

  2. An Experimental Study on the Stability of Superplastic Deformation of AZ31 Mg Alloy

    SciTech Connect

    Abu-Farha, F. K.; Nazzal, M. A.; Khraisheh, M. K.

    2007-04-07

    Optimum variable strain rate forming paths based on two different multiscale deformation-based stability criteria were developed. These criteria account for both geometrical necking (macroscopic feature) and microstructural evolution. In the first criterion, we defined the onset of instability using Hart's stability analysis, where a linear perturbation in a small region along the tensile specimen is introduced. In the second criterion, we introduced a modified one dimensional nonlinear long wavelength analysis, based on the one introduced by Hutchinson and Neale. The two stability criteria are calibrated for the AZ31 magnesium alloy at 400 deg. C, yielding two different variable strain rate forming paths. Uniaxial tensile tests are carried out following the derived forming paths to examine the validity of both criteria. Results show that the linear approach underestimates the amount of uniform deformation, and therefore prolongs the forming time to prevent failure compared to the nonlinear analysis.

  3. Effect of preheat on TIG welding of AZ61 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Shen, Jun; Xu, Nan

    2012-04-01

    The effects of preheat treatments on the microstructures and mechanical properties of tungsten inert gas (TIG)-welded AZ61 magnesium alloy joints were studied by microstructural observations, microhardness tests and tensile tests. The results showed that the volume fraction of the lamellar ?-Mg17(Al,Zn)12 intermetallic compound of in fusion zone (FZ) increased from 15% to 66% with an increase in preheat temperature. Moreover, the microhardness of the FZ and the ultimate tensile strength of the welded joints reached their maximum values when the preheat temperature was 300C because more lamellar ?-Mg17(Al,Zn)12 intermetallic compounds were distributed at the ?-Mg grain boundaries and no cracks and pores formed in the FZ of the welded joint.

  4. Die-casting effect on surface characteristics of thin-walled AZ91D magnesium components

    NASA Astrophysics Data System (ADS)

    Hu, Lifang; Chen, Shaoping; Miao, Yang; Meng, Qingsen

    2012-11-01

    Filling trace, filling time and temperature distribution during the die-casting process were simulated using commercial software (MAGMA). The surface microstructure and phase distribution in thin-walled AZ91D magnesium components cast on a hot-chamber die-casting machine were investigated by means of optical microscopy and scanning electron microscopy. The depth profile of alloying elements was examined using a glow discharge optical emission spectrometer. The outer skin microstructure consists of more ?-phase and less eutectic ?-phase than the interior region. The elemental content of C, Si, and Fe in the outer skin increased along the filling trace, and they decreased with increasing distance from the surface to the interior region, while the Al had an inverse trend. The corrosion resistance decreased along the filling trace.

  5. Microstructural Aspects of Damage and Fracture in AZ31 Sheet Materials

    NASA Astrophysics Data System (ADS)

    Kang, Jidong; Wilkinson, David S.; Mishra, Raja K.; Embury, J. David; Essadiqi, Elhachmi; Javaid, Amjad

    2013-05-01

    There are considerable data in the literature dealing with deformation mechanisms in AZ31 sheets. However, there is little information on the damage and fracture processes in this material. In this contribution, digital image correlation is used to follow deformation patterns occurring during tensile and v-bending tests at room temperature. A variety of surface analysis techniques and three-dimensional x-ray tomography have been used to examine the relationship between deformation, damage initiation, and the final fracture processes. The results show that premature diffuse necking occurs in the tensile tests without transit into localized necking. Deformation twins cluster by an autocatalytic process to form shear bands serving as preferential sites for strain localization and crack initiation. Damage appears in the form of microcracks within the shear bands at a late stage of necking and lead to the final fracture. The presence and the distribution of second-phase particles and their distributions help accelerate the final fracture processes.

  6. Statistical analysis on static recrystallization texture evolution in cold-rolled AZ31 magnesium alloy sheet.

    PubMed

    Park, Jun-Ho; Ahn, Tae-Hong; Choi, Hyun-Sik; Chung, Jung-Man; Kim, Dong-Ik; Oh, Kyu Hwan; Han, Heung Nam

    2013-08-01

    Cast AZ31B-H24 magnesium alloy, comprising Mg with 3.27 wt% Al and 0.96 wt% Zn, was cold rolled and subsequently annealed. Global texture evolutions in the specimens were observed by X-ray diffractometry after the thermomechanical processing. Image-based microstructure and texture for the deformed, recrystallized, and grown grains were observed by electron backscattered diffractometry. Recrystallized grains could be distinguished from deformed ones by analyzing grain orientation spread. Split basal texture of ca. 10-15 in the rolling direction was observed in the cold-rolled sample. Recrystallized grains had widely spread basal poles at nucleation stage; strong {0001} basal texture developed with grain growth during annealing. PMID:23920167

  7. Laser beam welding of AZ31B-H24 magnesium alloy.

    SciTech Connect

    Leong, K. H.

    1998-09-29

    The laser beam weldability of AZ31B magnesium alloy was examined with high power CW CO{sub 2} and pulsed Nd:YAG lasers. The low viscosity and surface tension of the melt pool make magnesium more difficult to weld than steel. Welding parameters necessary to obtain good welds were determined for both CW CO{sub 2} and pulsed Nd:YAG lasers. The weldability of the magnesium alloy was significantly better with the Nd:YAG laser. The cause of this improvement was attributed to the higher absorption of the Nd:YAG beam. A lower threshold beam irradiance was required for welding, and a more stable weldpool was obtained.

  8. Formation of Ha-Containing Coating on AZ31 Magnesium Alloy by Micro-Arc Oxidation

    NASA Astrophysics Data System (ADS)

    Tang, Hui; Li, Deyu; Chen, Xiuping; Wu, Chao; Wang, Fuping

    2013-08-01

    Magnesium and its alloys are potential biodegradable implant materials due to their attractive biological properties. But the use of magnesium is still hampered by its poor corrosion resistance in physiological fluids. In this study, a HA-containing coating was fabricated by micro-arc oxidation (MAO). The active plasma species of micro-discharge was studied by optical emission spectroscopy (OES). The microstructure and composition were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion behavior and apatite-forming ability were studied by electrochemical tests and immersed samples in simulated body fluids (SBF). The results show that the microdischarge channel model is gas discharges and oxide layer discharges. The elements from the substrate and electrolyte take part in the formation of the coating. The MAO coating significantly improves the corrosion resistance of AZ31 magnesium alloy and enhances the apatite formation ability.

  9. Fatigue behaviour of friction stir processed AZ91 magnesium alloy produced by high pressure die casting

    SciTech Connect

    Cavaliere, P. . E-mail: pasquale.cavaliere@unile.it; De Marco, P.P.

    2007-03-15

    The room temperature fatigue properties of AZ91 magnesium alloy produced by high pressure die casting (HPDC) as cast, heat treated, friction stir processed (FSP) and FSP and heat treated were studied. The fatigue properties of the material were evaluated for the HPDC magnesium alloy in the as-received state and after a solution treatment at 415 deg. C for 2 h and an ageing treatment at 220 deg. C for 4 h. The heat treatment resulted in a significant increase in the fatigue properties of the HPDC material, while no significance influence of heat treatment was recorded in the FSP condition. The morphology of fracture surfaces was examined by employing a field emission gun scanning electron microscope (FEGSEM)

  10. Microstructure, texture, and residual stress in a friction stir processed AZ31B magnesium alloy

    SciTech Connect

    Woo, Wan Chuck; Choo, Hahn; Feng, Zhili; Clausen, B; Prime, Michael B

    2008-01-01

    Spatial variations of microstructure, hardness, chemical composition, tensile behavior, texture and residual stresses were investigated in a friction-stir-processed (FSP) AZ31B magnesium alloy. The residual stresses were measured using two different methods: neutron diffraction and the contour method. No significant variations in the hardness and chemical compositions were found in the FSP zones, including the severely deformed stir zone (SZ), which showed a finer grain size compared to the heat-affected zone and base material. On the other hand, significant changes in the tensile yield strength, texture, and residual stresses were observed in the FSP zones. The relationship between the texture variations and yield strength reduction; and its influence on the decrease in the residual stress near the SZ is discussed. Finally, the residual stresses measured by neutron diffraction and the contour method are compared and the effect of the texture on neutron diffraction residual stress measurements is discussed.

  11. Sinking Coastal Cities

    NASA Astrophysics Data System (ADS)

    Erkens, G.; Stuurman, R.; De Lange, G.; Bucx, T.; Lambert, J.

    2014-12-01

    In many coastal cities land subsidence now exceeds absolute sea level rise up to a factor of ten. Without action, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other coastal cities will continue to sink, even below sea level. The ever increasing industrial and domestic demand for water in these cities results in excessive groundwater extraction, causing severe subsidence. In addition, coastal cities are often faced with larger natural subsidence, as they are built on thick sequences of soft soil. The impacts of subsidence are further exacerbated by climate-induced sea level rise. Land subsidence results in two types damage: foremost it increases flood vulnerability (frequency, inundation depth and duration of floods), with floods causing major economic damage and loss of lives. Secondly, differential land movement causes significant economic losses in the form of structural damage and high maintenance costs of roads and transportation networks, sewage systems, buildings and foundations. The total damage worldwide is estimated at billions of dollars annually. To survey the extent of groundwater associated subsidence, we conducted a quick-assessment of subsidence in a series of mega-cities (Jakarta, Ho Chi Minh City, Dhaka, New Orleans and Bangkok). For each city research questions included: what are the main causes, how much is the current subsidence rate and what are predictions, where are the vulnerable areas, what are the impacts and risks, how can adverse impacts can be mitigated or compensated for, and what governmental bodies are involved and responsible to act? Using the assessment, this paper discusses subsidence modelling and measurement results from the selected cities. The focus is on the importance of delayed settlement after increases in hydraulic heads, the role of the subsurface composition for subsidence rates and best practice solutions for subsiding cities. For the latter, urban (ground)water management, adaptive flood risk management and related spatial planning strategies are just examples of the options available. The discussions in this paper form the building blocks for a much-needed research agenda that aims to deliver a strategy to deal with subsidence in current and future subsidence-prone areas.

  12. Heat Treatment of AZ91D Mg-Al-Zn Alloy: Microstructural Evolution and Dynamic Response

    NASA Astrophysics Data System (ADS)

    Luong, Dung D.; Shunmugasamy, Vasanth Chakravarthy; Cox, James; Gupta, Nikhil; Rohatgi, Pradeep K.

    2013-11-01

    Magnesium alloys are attracting great interest from the automotive industry because of the potential for weight reduction. An AZ91D cast alloy was studied in the current work to understand the effect of heat treatment on the microstructure and dynamic compressive properties. The selected heat treatments include solution treatment (T4) and solution treatment followed by aging (T6). The as-cast alloy microstructure consists of intermetallic ?-phase (Mg17Al12) precipitates surrounded by ? + ? lamellar eutectic in ?-Mg solid solution. The AZ91D-T4 specimens showed small ?-phase precipitates along the grain boundaries and regions of eutectic mixture. The T6 heat treatment causes the ?-phase platelets in the ? + ? eutectic to grow and develop into ?-precipitates. The difference in the phase morphology reflects into the mechanical properties. The Vickers hardness of the T6 heat-treated specimens was 3.6% higher than the as-cast alloy. The compressive yield strengths of T4 and T6 treated specimens were 1.3% and 43.1% higher than those of as-cast specimens. The high strain rate compression testing resulted in increase in the strength with strain rate for the T4 and T6 specimens. A maximum increase of 42% was observed in T6 specimen tested at a strain rate of 4,000/s in comparison to the quasi-static compression. Under high strain rate compression testing, the T6 heat-treated specimens showed failure of the ?-precipitates resulting in increased energy absorption in comparison to the quasi-static compression.

  13. Archaeological studies at Drill Hole U20az Pahute Mesa, Nye county, Nevada. [Contains bibliography

    SciTech Connect

    Simmons, A.H.; Hemphill, M.L.; Henton, G.H.; Lockett, C.L.; Nials, F.L.; Pippin, L.C.; Walsh, L.

    1991-07-01

    During the summer of 1987, the Quaternary Sciences Center (formerly Social Science Center) of the Desert Research Institute (DRI), University of Nevada System, conducted data recovery investigations at five archaeological sites located near Drill Hole U20az on the Nevada Test Site in southern Nevada. These sites were among 12 recorded earlier during an archaeological survey of the drill hole conducted as part of the environmental compliance activities of the Department of Energy (DOE). The five sites discussed in this report were considered eligible for the National Register of Historic Places and were in danger of being adversely impacted by construction activities or by effects of the proposed underground nuclear test. Avoidance of these sites was not a feasible alternative; thus DRI undertook a data recovery program to mitigate expected adverse impacts. DRI's research plan included controlled surface collections and excavation of the five sites in question, and had the concurrence of the Nevada Division of Historic Preservation and Archaeology and the Advisory Council of Historic Preservation. Of the five sites investigated, the largest and most complex, 26Ny5207, consists of at least three discrete artifact concentrations. Sites 26Ny5211 and 26Ny5215, both yielded considerable assemblages. Site 26Ny5206 is very small and probably is linked to 26Ny5207. Site 26Ny5205 contained a limited artifact assemblage. All of the sites were open-air occurrences, and, with one exception contained no or limited subsurface cultural deposits. Only two radiocarbon dates were obtained, both from 26Ny5207 and both relatively recent. While the investigations reported in the volume mitigate most of the adverse impacts from DOE activities at Drill Hole U20az, significant archaeological sites may still exist in the general vicinity. Should the DOE conduct further activities in the region, additional cultural resource investigations may be required. 132 refs., 71 figs., 44 tabs.

  14. Software configuration management plan, 241-AY and 241-AZ tank farm MICON automation system

    SciTech Connect

    Hill, L.F.

    1997-10-30

    This document establishes a Computer Software Configuration Management Plan (CSCM) for controlling software for the MICON Distributed Control System (DCS) located at the 241-AY and 241-AZ Aging Waste Tank Farm facilities in the 200 East Area. The MICON DCS software controls and monitors the instrumentation and equipment associated with plant systems and processes. A CSCM identifies and defines the configuration items in a system (section 3.1), controls the release and change of these items throughout the system life cycle (section 3.2), records and reports the status of configuration items and change requests (section 3.3), and verifies the completeness and correctness of the items (section 3.4). All software development before initial release, or before software is baselined, is considered developmental. This plan does not apply to developmental software. This plan applies to software that has been baselined and released. The MICON software will monitor and control the related instrumentation and equipment of the 241-AY and 241-AZ Tank Farm ventilation systems. Eventually, this software may also assume the monitoring and control of the tank sludge washing equipment and other systems as they are brought on line. This plan applies to the System Cognizant Manager and MICON Cognizant Engineer (who is also referred to herein as the system administrator) responsible for the software/hardware and administration of the MICON system. This document also applies to any other organizations within Tank Farms which are currently active on the system including system cognizant engineers, nuclear operators, technicians, and control room supervisors.

  15. Earth's City Lights

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This image of Earth's city lights was created with data from the Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS). Originally designed to view clouds by moonlight, the OLS is also used to map the locations of permanent lights on the Earth's surface. The brightest areas of the Earth are the most urbanized, but not necessarily the most populated. (Compare western Europe with China and India.) Cities tend to grow along coastlines and transportation networks. Even without the underlying map, the outlines of many continents would still be visible. The United States interstate highway system appears as a lattice connecting the brighter dots of city centers. In Russia, the Trans-Siberian railroad is a thin line stretching from Moscow through the center of Asia to Vladivostok. The Nile River, from the Aswan Dam to the Mediterranean Sea, is another bright thread through an otherwise dark region. Even more than 100 years after the invention of the electric light, some regions remain thinly populated and unlit. Antarctica is entirely dark. The interior jungles of Africa and South America are mostly dark, but lights are beginning to appear there. Deserts in Africa, Arabia, Australia, Mongolia, and the United States are poorly lit as well (except along the coast), along with the boreal forests of Canada and Russia, and the great mountains of the Himalaya. The Earth Observatory article Bright Lights, Big City describes how NASA scientists use city light data to map urbanization. Image by Craig Mayhew and Robert Simmon, NASA GSFC, based on DMSP data

  16. The Role of Trans Tensional Structures and Lake Mead Reservoir in Groundwater Flow in Black Canyon, Lake Mead National Recreation Area, NV-AZ

    NASA Astrophysics Data System (ADS)

    Justet, L.; Beard, S.

    2010-12-01

    Hot springs and seeps discharging into Black Canyon (BC) along the Colorado River in north Colorado River Valley (CRV) support endemic riparian ecosystems in the Lake Mead National Recreation Area. Increases in groundwater development in southern NV and northwestern AZ may impact spring discharge. Sources of spring discharge in BC were evaluated using geochemical methods. Kinematic analysis and geologic mapping of structures associated with BC springs were used to evaluate structural controls on groundwater flow in BC. Geochemical analysis indicates groundwater discharge near Hoover Dam (HD) and along the faulted edge of the Boulder City Pluton is derived from Lake Mead, high ?87Sr Proterozoic or Tertiary crystalline rock and, possibly, Tertiary sedimentary rock. Reducing conditions indicated by 234U/238U and ?34S concentrations suggest the groundwater is confined and/or derived from greater depths while carbon isotopes indicate the groundwater is old. Lighter ?D and ?O-18, modern tritium concentrations, post-Dam U disequilibrium ages, and occurrence of anthropogenic perchlorate support the presence of a young Lake Mead component. South of the pluton, the Lake Mead component is absent. More oxidizing conditions in this part of BC, indicated by the U and S isotope concentrations, suggest the groundwater is less confined and/or derived from shallower depths compared to groundwater discharging near HD. Older apparent groundwater ages and heavier ?D and ?O-18 values south of the pluton indicate slower flow paths from a lower elevation or latitude source. Clarifying the nature of groundwater flow in eastern NV, the analyses indicate that hydraulic connection between the regional carbonate aquifer and BC is unlikely. Instead, the data indicate sources of BC springs are derived relatively locally in CRV and, possibly, south Lake Mead Valley. Results of the geologic and kinematic analyses indicate faults that formed from the interaction of E-W extension related to the AZ extensional corridor and NW-SE trans tension related to the Lake Mead shear zone are the main controls on groundwater flow in the vicinity of HD and Boulder City Pluton. Most groundwater in BC appears to discharge along the NW-striking Palm Tree fault that parallels the northern edge of the pluton. Supported by trends in chemistry, an alignment of similar-elevation springs along a N-S striking fault that extends the length of west BC may be a flow path for groundwater from north BC to south of the pluton. South of the pluton, dikes intrude many of the faults and appear to act as flow barriers. Groundwater in this part of BC may flow through stacked layers of brecciated volcanic rock prevalent in the area. Flow from laterally adjacent valleys into BC would have to cross a N-S structural fabric that is not favored kinematically. Existing information implies an overall absence of significant surface discharge in BC prior to construction of HD. This indicates that the head created by impoundment of the Colorado River has likely pushed old, slow moving groundwater through CRV and, possibly, south Lake Mead Valley, to the surface in BC where it discharges as springs and seeps.

  17. Reproducing in cities.

    PubMed

    Mace, Ruth

    2008-02-01

    Reproducing in cities has always been costly, leading to lower fertility (that is, lower birth rates) in urban than in rural areas. Historically, although cities provided job opportunities, initially residents incurred the penalty of higher infant mortality, but as mortality rates fell at the end of the 19th century, European birth rates began to plummet. Fertility decline in Africa only started recently and has been dramatic in some cities. Here it is argued that both historical and evolutionary demographers are interpreting fertility declines across the globe in terms of the relative costs of child rearing, which increase to allow children to outcompete their peers. Now largely free from the fear of early death, postindustrial societies may create an environment that generates runaway parental investment, which will continue to drive fertility ever lower. PMID:18258904

  18. Finding the Lost City

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Nicholas Clapp, a filmmaker and archeology enthusiast, had accumulated extensive information concerning Ubar, the fabled lost city of ancient Arabia. When he was unable to identify its exact location, however, he turned to the Jet Propulsion Laboratory (JPL) for assistance in applying orbital remote sensing techniques. JPL scientists searched NASA's shuttle imaging radar, as well as Landsat and SPOT images and discovered ancient caravan tracks. This enabled them to prepare a map of the trails, which converged at a place known as Ash Shisr. An expedition was formed, which found structures and artifacts from a city that predates previous area civilization by a thousand years. Although it will take time to validate the city as Ubar, the discovery is a monumental archeological triumph.

  19. Ultrafine particles in cities.

    PubMed

    Kumar, Prashant; Morawska, Lidia; Birmili, Wolfram; Paasonen, Pauli; Hu, Min; Kulmala, Markku; Harrison, Roy M; Norford, Leslie; Britter, Rex

    2014-05-01

    Ultrafine particles (UFPs; diameter less than 100 nm) are ubiquitous in urban air, and an acknowledged risk to human health. Globally, the major source for urban outdoor UFP concentrations is motor traffic. Ongoing trends towards urbanisation and expansion of road traffic are anticipated to further increase population exposure to UFPs. Numerous experimental studies have characterised UFPs in individual cities, but an integrated evaluation of emissions and population exposure is still lacking. Our analysis suggests that the average exposure to outdoor UFPs in Asian cities is about four-times larger than that in European cities but impacts on human health are largely unknown. This article reviews some fundamental drivers of UFP emissions and dispersion, and highlights unresolved challenges, as well as recommendations to ensure sustainable urban development whilst minimising any possible adverse health impacts. PMID:24503484

  20. Inner City Asthma

    PubMed Central

    Togias, Alkis

    2014-01-01

    SYNOPSIS The inner city has long been recognized as an area of high asthma morbidity and mortality. A wide range of factors interact to create this environment. These factors include well-recognized asthma risk factors that are not specific to the inner city, the structure and delivery of health care, the location and function of the urban environment, and social inequities. This article will review these facets and discuss successful and unsuccessful interventions in order to understand what is needed to solve this problem. PMID:25459579

  1. H2A.Z depletion impairs proliferation and viability but not DNA double-strand breaks repair in human immortalized and tumoral cell lines

    PubMed Central

    Taty-Taty, Gemael-Cedrick; Courilleau, Celine; Quaranta, Muriel; Carayon, Alexandre; Chailleux, Catherine; Aymard, Franois; Trouche, Didier; Canitrot, Yvan

    2014-01-01

    In mammalian cells, DNA double-strand breaks (DSB) can be repaired by 2 main pathways, homologous recombination (HR) and non-homologous end joining (NHEJ). To give access to DNA damage to the repair machinery the chromatin structure needs to be relaxed, and chromatin modifications play major roles in the control of these processes. Among the chromatin modifications, changes in nucleosome composition can influence DNA damage response as observed with the H2A.Z histone variant in yeast. In mammals, p400, an ATPase of the SWI/SNF family able to incorporate H2A.Z in chromatin, was found to be important for histone ubiquitination and BRCA1 recruitment around DSB or for HR in cooperation with Rad51. Recent data with 293T cells showed that mammalian H2A.Z is recruited to DSBs and is important to control DNA resection, therefore participating both in HR and NHEJ. Here we show that depletion of H2A.Z in the osteosarcoma U2OS cell line and in immortalized human fibroblasts does not change parameters of DNA DSB repair while affecting clonogenic ability and cell cycle distribution. In addition, no recruitment of H2A.Z around DSB can be detected in U2OS cells either after local laser irradiation or by chromatin immunoprecipitation. These data suggest that the role of H2A.Z in DSB repair is not ubiquitous in mammals. In addition, given that important cellular parameters, such as cell viability and cell cycle distribution, are more sensitive to H2A.Z depletion than DNA repair, our results underline the difficulty to investigate the role of versatile factors such as H2A.Z. PMID:24240188

  2. The Lysobacter capsici AZ78 Genome Has a Gene Pool Enabling it to Interact Successfully with Phytopathogenic Microorganisms and Environmental Factors

    PubMed Central

    Puopolo, Gerardo; Tomada, Selena; Sonego, Paolo; Moretto, Marco; Engelen, Kristof; Perazzolli, Michele; Pertot, Ilaria

    2016-01-01

    Lysobacter capsici AZ78 has considerable potential for biocontrol of phytopathogenic microorganisms. However, lack of information about genetic cues regarding its biological characteristics may slow down its exploitation as a biofungicide. In order to obtain a comprehensive overview of genetic features, the L. capsici AZ78 genome was sequenced, annotated and compared with the phylogenetically related pathogens Stenotrophomonas malthophilia K729a and Xanthomonas campestris pv. campestris ATCC 33913. Whole genome comparison, supported by functional analysis, indicated that L. capsici AZ78 has a larger number of genes responsible for interaction with phytopathogens and environmental stress than S. malthophilia K729a and X. c. pv. campestris ATCC 33913. Genes involved in the production of antibiotics, lytic enzymes and siderophores were specific for L. capsici AZ78, as well as genes involved in resistance to antibiotics, environmental stressors, fungicides and heavy metals. The L. capsici AZ78 genome did not encompass genes involved in infection of humans and plants included in the S. malthophilia K729a and X. c. pv. campestris ATCC 33913 genomes, respectively. The L. capsici AZ78 genome provides a genetic framework for detailed analysis of other L. capsici members and the development of novel biofungicides based on this bacterial strain. PMID:26903975

  3. The Lysobacter capsici AZ78 Genome Has a Gene Pool Enabling it to Interact Successfully with Phytopathogenic Microorganisms and Environmental Factors.

    PubMed

    Puopolo, Gerardo; Tomada, Selena; Sonego, Paolo; Moretto, Marco; Engelen, Kristof; Perazzolli, Michele; Pertot, Ilaria

    2016-01-01

    Lysobacter capsici AZ78 has considerable potential for biocontrol of phytopathogenic microorganisms. However, lack of information about genetic cues regarding its biological characteristics may slow down its exploitation as a biofungicide. In order to obtain a comprehensive overview of genetic features, the L. capsici AZ78 genome was sequenced, annotated and compared with the phylogenetically related pathogens Stenotrophomonas malthophilia K729a and Xanthomonas campestris pv. campestris ATCC 33913. Whole genome comparison, supported by functional analysis, indicated that L. capsici AZ78 has a larger number of genes responsible for interaction with phytopathogens and environmental stress than S. malthophilia K729a and X. c. pv. campestris ATCC 33913. Genes involved in the production of antibiotics, lytic enzymes and siderophores were specific for L. capsici AZ78, as well as genes involved in resistance to antibiotics, environmental stressors, fungicides and heavy metals. The L. capsici AZ78 genome did not encompass genes involved in infection of humans and plants included in the S. malthophilia K729a and X. c. pv. campestris ATCC 33913 genomes, respectively. The L. capsici AZ78 genome provides a genetic framework for detailed analysis of other L. capsici members and the development of novel biofungicides based on this bacterial strain. PMID:26903975

  4. Tensile properties of AZ11A-0 magnesium-alloy sheet under rapid-heating and constant temperature

    NASA Technical Reports Server (NTRS)

    Kurg, Ivo M

    1956-01-01

    Specimens of AZ31A-0 magnesium alloy sheet were heated to rupture at nominal rates of 0.2 F to 100 F per second under constant tensile load conditions. The data are presented and compared with the results of conventional tensile stress-strain tests at elevated temperatures after 1.2-hour exposure. A temperature-rate parameter was used to construct master curves from which stresses and temperatures for yield and rupture can be predicted under rapid-heating conditions. A comparison of the elevated-temperature tensile properties of AZ31A-0 and HK31XA-H24 magnesium-alloy sheet under both constant-temperature and rapid-heating conditions is included.

  5. Investigations on the Stress and Strain Evolution in AZ91D Magnesium Alloy Castings During Hot Tearing

    NASA Astrophysics Data System (ADS)

    Bichler, L.; Ravindran, C.

    2015-06-01

    Hot tearing in magnesium and aluminum alloys has been rigorously investigated in the past decades. To date, the interactions between the solidification parameters, microstructural development, and stress and strain at the onset of hot tearing in magnesium alloys remain unclear. In particular, the stress and strain conditions required to nucleate hot tears are unknown. In this research, ex situ neutron diffraction residual strain mapping was carried out on AZ91D magnesium alloy castings at the onset of hot tearing. The results indicate that tensile strain alone was not sufficient to nucleate a hot tear. A minimum threshold tensile stress of ~12 MPa was necessary to open interdendritic shrinkage pores into hot tears and enable their propagation. Further, deformation along and crystallographic planes played a dominant role on the high-temperature deformation and hot tearing in the AZ91D alloy.

  6. Microstructural Analysis of Severe Plastic Deformed Twin Roll Cast AZ31 for the Optimization of Superplastic Properties

    SciTech Connect

    Young, John P.; Askari, Hesam A.; Heiden, Michael J.; Hovanski, Yuri; Field, David P.; Zbib, Hussein M.

    2013-07-08

    In recent years magnesium alloys have attracted significant attention as potential candidates to replace many of the heavier metals used in some automotive applications. However, the limited formability of magnesium and its alloys at room temperature has driven interest in the superplastic forming magnesium as an alternative shaping method. Severe plastic deformation techniques have become a well studied method of refining the grain size and modifying the microstructural characteristics of many magnesium alloys to achieve greater superplastic properties. In this study twin roll cast (TRC) AZ31 magnesium alloy was subjected to equal channel angular pressing (ECAP) and friction stir welding (FSW). The influence of these severe plastic deformation processes on the grain size, texture and grain boundary character distribution was investigated to identify the optimum severe plastic deformation process for the superplastic forming of AZ31.

  7. Study on the microstructural evolution of AZ31 magnesium alloy in a vertical twin-roll casting process

    NASA Astrophysics Data System (ADS)

    Chen, Ming; Hu, Xiao-Dong; Han, Bing; Deng, Xiao-Hu; Ju, Dong-Ying

    2016-02-01

    Finite element method was employed to calculate the macroflow velocity and temperature distribution of the pool domain's biting zone in twin-roll casting. Macroanalysis results were inducted as boundary conditions into microanalysis. Phase field method (PFM) was adopted to investigate the microstructure evolution. Based on the Kim-Kim-Suzuki model, the effect of metal flow velocity was coupled on the solute gradient item, and the real physical parameters of AZ31 were inducted into the numerical calculation. We used the marker and cell method in the discrete element solution of microstructural pattern prediction of AZ31 magnesium alloys. The different flow velocity values that predicted the columnar dendrite evolution were discussed in detail. Numerical simulation results were also compared with the experiment analysis. The microstructure obtained by PFM agrees with the actual pattern observed via optical microscopy.

  8. A Crystalline Plasticity Finite Element Method for Simulation of the Plastic Deformation of AZ31 Magnesium Alloys

    SciTech Connect

    Li Dayong; Peng Yinghong; Zhang Shaorui; Tang Weiqin; Huang Shiyao

    2010-06-15

    In this paper, a constitutive framework based on a crystalline plasticity model is employed to simulate the plastic deformation of AZ31 magnesium alloy, which posses the hexagonal close packed (HCP) crystal structure. Dislocation slip and mechanical twinning are taken into account in the model. The successive integration method is used to determine the active slip systems, and the contribution of twinning to the grain reorientation is treated by the PTR method. The FE model is introduced into ABAQUS/Explicit through a user material subroutine (VUMAT). Three deformation processes of AZ31 magnesium alloy, including tension, compression and a stamping process, are simulated with the present method. The simulation results are compared with experiment and those presented in the literature.

  9. PHYSICAL CHARACTERIZATION OF VITREOUS STATE LABORATORY AY102/C106 AND AZ102 HIGH LEVEL WASTE MELTER FEED SIMULANTS (U)

    SciTech Connect

    Hansen, E

    2005-03-31

    The objective of this task is to characterize and report specified physical properties and pH of simulant high level waste (HLW) melter feeds (MF) processed through the scaled melters at Vitreous State Laboratories (VSL). The HLW MF simulants characterized are VSL AZ102 straight hydroxide melter feed, VSL AZ102 straight hydroxide rheology adjusted melter feed, VSL AY102/C106 straight hydroxide melter feed, VSL AY102/C106 straight hydroxide rheology adjusted melter feed, and Savannah River National Laboratory (SRNL) AY102/C106 precipitated hydroxide processed sludge blended with glass former chemicals at VSL to make melter feed. The physical properties and pH were characterized using the methods stated in the Waste Treatment Plant (WTP) characterization procedure (Ref. 7).

  10. Corrosion mechanism and model of pulsed DC microarc oxidation treated AZ31 alloy in simulated body fluid

    NASA Astrophysics Data System (ADS)

    Gu, Yanhong; Chen, Cheng-fu; Bandopadhyay, Sukumar; Ning, Chengyun; Zhang, Yongjun; Guo, Yuanjun

    2012-06-01

    This paper addresses the effect of pulse frequency on the corrosion behavior of microarc oxidation (MAO) coatings on AZ31 Mg alloys in simulated body fluid (SBF). The MAO coatings were deposited by a pulsed DC mode at four different pulse frequencies of 300 Hz, 500 Hz, 1000 Hz and 3000 Hz with a constant pulse ratio. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests were used for corrosion rate and electrochemical impedance evaluation. The corroded surfaces were examined by X-ray diffraction (XRD), X-ray fluorescence (XRF) and optical microscopy. All the results exhibited that the corrosion resistance of MAO coating produced at 3000 Hz is superior among the four frequencies used. The XRD spectra showed that the corrosion products contain hydroxyapatite, brucite and quintinite. A model for corrosion mechanism and corrosion process of the MAO coating on AZ31 Mg alloy in the SBF is proposed.

  11. Summer in the City

    ERIC Educational Resources Information Center

    Gewertz, Catherine

    2005-01-01

    This article describes the different experiences of the participants in an Outward Bound-sponsored "urban expedition" to New York City that was designed to make them better teachers by examining their beliefs and biases. The participants in this "urban expedition" came from schools that work with Outward Bound USA, the Garrison, New York,

  12. Accepted into Education City

    ERIC Educational Resources Information Center

    Asquith, Christina

    2006-01-01

    Qatar's Education City, perhaps the world's most diverse campus, is almost entirely unknown in the United States, but represents the next step in the globalization of American higher education--international franchising. Aided by technology such as online libraries, distance learning and streaming video, U.S. universities offer--and charge tuition

  13. India's Cities in Crisis.

    ERIC Educational Resources Information Center

    Bryjak, George J.

    1984-01-01

    Indian cities are growing rapidly due to natural increase and migration from rural areas. This has caused huge pollution problems and has resulted in overcrowded schools and hospitals. Conflict between religious groups has increased; so has crime. India is modernizing, but not fast enough. (CS)

  14. Tackling Inner City Problems.

    ERIC Educational Resources Information Center

    Liddle, D. W.

    1979-01-01

    Describes a succession of government initiatives that challenge many metropolitan district and London borough library authorities to take advantage of increasing urban aid to tackle inner city problems relating to education, employment, and culture. An examination of the Inner Urban Areas Act of 1978 details the implementation of such initiative.

  15. Big-City Rules

    ERIC Educational Resources Information Center

    Gordon, Dan

    2011-01-01

    When it comes to implementing innovative classroom technology programs, urban school districts face significant challenges stemming from their big-city status. These range from large bureaucracies, to scalability, to how to meet the needs of a more diverse group of students. Because of their size, urban districts tend to have greater distance…

  16. Bug City: Ants [Videotape].

    ERIC Educational Resources Information Center

    1998

    "Bug City" is a video series created to help children (grades 1-6) learn about insects and other small critters. All aspects of bug life are touched upon including body structure, food, habitat, life cycle, mating habits, camouflage, mutualism (symbiosis), adaptations, social behavior, and more. Each program features dramatic microscopic

  17. America's Most Literate Cities.

    ERIC Educational Resources Information Center

    Miller, Jack

    This study assessed factors related to literacy and literate behavior, rating the most and least literate U.S. cities. Data came from the U.S. Census Bureau, Audit Bureau of Circulations, American Booksellers Association, Yellow Pages, American Library Directory, and National Directory of Magazines. Thirteen measures were combined to form five…

  18. Atlantic City memories.

    PubMed

    Epstein, Franklin H

    2008-04-01

    Fifty years ago, the Atlantic City meetings, held the first week in May of every year, were attended by all the elite of American academic medicine and all who wanted to join that group. Part of the magic of those meetings was that professors and neophytes took each other seriously and talked to each other. PMID:18382726

  19. New City, New Challenges

    ERIC Educational Resources Information Center

    Matthews, Frank

    2010-01-01

    After eight years at the helm of the City College of New York, where Dr. Gregory Williams grew enrollment at the minority-serving institution by 60 percent, instituted more rigorous admissions standards and launched the college's first capital campaign that raised more than $300 million, last fall he became the 27th president of the University of

  20. Bug City: Beetles [Videotape].

    ERIC Educational Resources Information Center

    1998

    "Bug City" is a video series created to help children learn about insects and other small critters. All aspects of bug life are touched upon including body structure, food, habitat, life cycle, mating habits, camouflage, mutualism (symbiosis), adaptations, social behavior, and more. Each program features dramatic microscopic photography, fun

  1. Bug City: Bees [Videotape].

    ERIC Educational Resources Information Center

    1998

    "Bug City" is a video series created to help children learn about insects and other small critters. All aspects of bug life are touched upon including body structure, food, habitat, life cycle, mating habits, camouflage, mutualism (symbiosis), adaptations, social behavior, and more. Each program features dramatic microscopic photography, fun

  2. The Plains City Story

    ERIC Educational Resources Information Center

    van Olphen, Marcela; Rios, Francisco; Berube, William; Dexter, Robin; McCarthy, Robert

    2006-01-01

    This case study portrays a contemporary phenomenon that affects many U.S. school districts. Specifically, the authors address the challenges that the superintendent of the Plains City school district faced as a result of a change in the demographic distribution of his district. The gradual development of the pig farming industry in Plains City…

  3. Big-City Rules

    ERIC Educational Resources Information Center

    Gordon, Dan

    2011-01-01

    When it comes to implementing innovative classroom technology programs, urban school districts face significant challenges stemming from their big-city status. These range from large bureaucracies, to scalability, to how to meet the needs of a more diverse group of students. Because of their size, urban districts tend to have greater distance

  4. New City, New Challenges

    ERIC Educational Resources Information Center

    Matthews, Frank

    2010-01-01

    After eight years at the helm of the City College of New York, where Dr. Gregory Williams grew enrollment at the minority-serving institution by 60 percent, instituted more rigorous admissions standards and launched the college's first capital campaign that raised more than $300 million, last fall he became the 27th president of the University of…

  5. Accepted into Education City

    ERIC Educational Resources Information Center

    Asquith, Christina

    2006-01-01

    Qatar's Education City, perhaps the world's most diverse campus, is almost entirely unknown in the United States, but represents the next step in the globalization of American higher education--international franchising. Aided by technology such as online libraries, distance learning and streaming video, U.S. universities offer--and charge tuition…

  6. Clean Cities Tools

    SciTech Connect

    2014-12-19

    The U.S. Department of Energy's Clean Cities offers a large collection of Web-based tools on the Alternative Fuels Data Center. These calculators, interactive maps, and data searches can assist fleets, fuels providers, and other transportation decision makers in their efforts to reduce petroleum use.

  7. City Kids Go Green.

    ERIC Educational Resources Information Center

    Taylor, Tricia

    1993-01-01

    Describes Outward Bound Urban Resources Initiative, a six-week summer course whose goal is to work with urban youth to develop solutions for local environmental problems. Among the activities described include converting city lots into parks, neighborhood cleanup, and tree planting. (MDH)

  8. Bug City: Bees [Videotape].

    ERIC Educational Resources Information Center

    1998

    "Bug City" is a video series created to help children learn about insects and other small critters. All aspects of bug life are touched upon including body structure, food, habitat, life cycle, mating habits, camouflage, mutualism (symbiosis), adaptations, social behavior, and more. Each program features dramatic microscopic photography, fun…

  9. Homage to Atlantic City

    PubMed Central

    Jr., Lloyd H. Smith

    2008-01-01

    In this article, I reflect on the unique value for the societies of academic internal medicine of their annual spring meetings that were held in Atlantic City for two generations prior to 1977 and consider whether lessons remain from those past experiences. PMID:18382728

  10. The New City Commons

    ERIC Educational Resources Information Center

    Crossland, Janice

    1975-01-01

    Cities throughout the country are sponsoring family projects that convert vacant lots and rooftops to productive neighborhood gardens. It is hoped that utilization of these otherwide wasted areas will provide extra food for low income families, as well as promote community spirit and organization. (MA)

  11. Sinking coastal cities

    NASA Astrophysics Data System (ADS)

    Erkens, Gilles; Bucx, Tom; Dam, Rien; De Lange, Ger; Lambert, John

    2014-05-01

    In many coastal and delta cities land subsidence now exceeds absolute sea level rise up to a factor of ten. Without action, parts of Jakarta, Ho Chi Minh City, Bangkok and numerous other coastal cities will sink below sea level. Land subsidence increases flood vulnerability (frequency, inundation depth and duration of floods), with floods causing major economic damage and loss of lives. In addition, differential land movement causes significant economic losses in the form of structural damage and high maintenance costs. This effects roads and transportation networks, hydraulic infrastructure - such as river embankments, sluice gates, flood barriers and pumping stations -, sewage systems, buildings and foundations. The total damage worldwide is estimated at billions of dollars annually. Excessive groundwater extraction after rapid urbanization and population growth is the main cause of severe land subsidence. In addition, coastal cities are often faced with larger natural subsidence, as they are built on thick sequences of soft soil. Because of ongoing urbanization and population growth in delta areas, in particular in coastal megacities, there is, and will be, more economic development in subsidence-prone areas. The impacts of subsidence are further exacerbated by extreme weather events (short term) and rising sea levels (long term).Consequently, detrimental impacts will increase in the near future, making it necessary to address subsidence related problems now. Subsidence is an issue that involves many policy fields, complex technical aspects and governance embedment. There is a need for an integrated approach in order to manage subsidence and to develop appropriate strategies and measures that are effective and efficient on both the short and long term. Urban (ground)water management, adaptive flood risk management and related spatial planning strategies are just examples of the options available. A major rethink is needed to deal with the 'hidden' but urgent threat of subsidence. As subsidence is spatially different and can be caused by multi processes, an assessment of subsidence in delta cities needs to answer questions such as: what are the main causes, how much is the current subsidence rate and what are future scenarios (and interaction with other major environmental issues), where are the vulnerable areas, what are the impacts and risks, how can adverse impacts can be mitigated or compensated for, and who is involved and responsible to act? In this study a quick-assessment of subsidence is performed on the following mega-cities: Jakarta, Ho Chi Minh City, Dhaka, New Orleans and Bangkok. Results of these case studies will be presented and compared, and a (generic) approach how to deal with subsidence in current and future subsidence-prone areas is provided.

  12. 26. 'CITY HOSPITAL, BLACKWELL'S ISLAND.' (Source: New York City Department ...

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

    26. 'CITY HOSPITAL, BLACKWELL'S ISLAND.' (Source: New York City Department of Public Finance, Real Estate Owned by the City of New York under Jurisdiction of the Department of Public Charities, 1909.) - Island Hospital, Roosevelt Island, New York, New York County, NY

  13. The interface characteristics of as-cast SiC{sub p}/Mg(AZ80) composite

    SciTech Connect

    Cai, Y.; Shen, G.J.; Su, H.Q.

    1997-09-15

    The interface physical and chemical characteristics between matrix and reinforcement are vital to the metal matrix composites (MMCs) properties. Interfacial studies usually include identification of the interfacial structure and/or reaction products and determination of crystallographic relationships. The aim of this paper is to study the interface of SiCp/AZ80 composite and determine the phase that formed at the interface. The mechanism of these phases formation is also discussed.

  14. Iron Phosphate Glass for Vitrifying Hanford AZ102 LAW in Joule Heated and Cold Crucible Induction Melters

    SciTech Connect

    Day, Delbert E.; Brow, R. K.; Ray, C. S.; Kim, Cheol-Woon; Reis, Signo T.; Vienna, John D.; Peeler, David K.; Johnson, Fabienne; Hansen, E. K.; Sevigny, Gary J.; Soelberg, Nicolas R.; Pegg, Ian L.; Gan, Hao

    2012-01-05

    An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) low activity Hanford waste, known as AZ102 LAW, has been developed for processing in a Joule Heated Melter (JHM) or a Cold Crucible Induction Melter (CCIM). This composition produced a glass waste form, designated as MS26AZ102F-2, with a waste loading of 26 wt% of the AZ102 which corresponded to a total alkali and sulfate (SO3) content of 21 and 4.2 wt%, respectively. A slurry (7M Na) of MS26AZ102F-2 simulant was melted continuously at temperatures between 1030 and 1090°C for 10 days in a small JHM at PNNL and for 7 days in a CCIM at INL. The as-cast glasses produced in both melters and in trial laboratory experiments along with their CCC-treated counterparts met the DOE LAW requirements for the Product Consistency Test (PCT) and the Vapor Hydration Test (VHT). These glass waste forms retained up to 77 % of the SO3 (3.3 wt%), 100% of the Cesium, and 33 to 44% of the rhenium, surrogate for Tc-99, all of which either exceeded or were comparable to the retention limit for these species in borosilicate glass nuclear waste form. Analyses of commercial K-3 refractory lining and the Inconel 693 metal electrodes used in JHM indicated only minimum corrosion of these components by the iron phosphate glass. This is the first time that an iron phosphate composition (slurry feed) was melted continuously in the JHM and CCIM, thereby, demonstrating that iron phosphate glasses can be used as alternative hosts for vitrifying nuclear waste.

  15. THE REDSHIFT AND NATURE OF AzTEC/COSMOS 1: A STARBURST GALAXY AT z = 4.6

    SciTech Connect

    Smolcic, V.; Capak, P.; Blain, A. W.; Salvato, M.; Masters, D.; Moric, I.; Riechers, D. A.; Ilbert, O.; Aretxaga, I.; Hughes, D.; Schinnerer, E.; Sheth, K.; Aravena, M.; Aussel, H.; Aguirre, J.; Berta, S.; Carilli, C. L.; Civano, F.; Fazio, G.; Huang, J.

    2011-04-20

    Based on broadband/narrowband photometry and Keck DEIMOS spectroscopy, we report a redshift of z = 4.64{sup +0.06}{sub -0.08} for AzTEC/COSMOS 1, the brightest submillimeter galaxy (SMG) in the AzTEC/COSMOS field. In addition to the COSMOS-survey X-ray to radio data, we report observations of the source with Herschel/PACS (100, 160 {mu}m), CSO/SHARC II (350 {mu}m), and CARMA and PdBI (3 mm). We do not detect CO(5 {yields} 4) line emission in the covered redshift ranges, 4.56-4.76 (PdBI/CARMA) and 4.94-5.02 (CARMA). If the line is within this bandwidth, this sets 3{sigma} upper limits on the gas mass to {approx}<8 x 10{sup 9} M{sub sun} and {approx}<5 x 10{sup 10} M{sub sun}, respectively (assuming similar conditions as observed in z {approx} 2 SMGs). This could be explained by a low CO-excitation in the source. Our analysis of the UV-IR spectral energy distribution of AzTEC 1 shows that it is an extremely young ({approx}<50 Myr), massive (M{sub *} {approx} 10{sup 11} M{sub sun}), but compact ({approx}<2 kpc) galaxy, forming stars at a rate of {approx}1300 M{sub sun} yr{sup -1}. Our results imply that AzTEC 1 is forming stars in a 'gravitationally bound' regime in which gravity prohibits the formation of a superwind, leading to matter accumulation within the galaxy and further generations of star formation.

  16. 241-AZ-101 Mixer Pump Demonstration Test Gamma Cart Acceptance Test Procedure and Quality Test Plan (ATP and QTP)

    SciTech Connect

    WHITE, D.A.

    2000-03-01

    Shop Test of the Gamma Cart System to be used in the AZ-101 Mixer Pump Demonstration Test. Tests hardware and software. This procedure involves testing the Instrumentation involved with the Gamma Cart System, local and remote, including: depth indicators, speed controls, interface to data acquisition software and the raising and lowering functions. This Procedure will be performed twice, once for each Gamma Cart System. This procedure does not test the accuracy of the data acquisition software.

  17. In vitro and in vivo studies of biodegradable fine grained AZ31 magnesium alloy produced by equal channel angular pressing.

    PubMed

    Ratna Sunil, B; Sampath Kumar, T S; Chakkingal, Uday; Nandakumar, V; Doble, Mukesh; Devi Prasad, V; Raghunath, M

    2016-02-01

    The objective of the present work is to investigate the role of different grain sizes produced by equal channel angular pressing (ECAP) on the degradation behavior of magnesium alloy using in vitro and in vivo studies. Commercially available AZ31 magnesium alloy was selected and processed by ECAP at 300C for up to four passes using route Bc. Grain refinement from a starting size of 46?m to a grain size distribution of 1-5?m was successfully achieved after the 4th pass. Wettability of ECAPed samples assessed by contact angle measurements was found to increase due to the fine grain structure. In vitro degradation and bioactivity of the samples studied by immersing in super saturated simulated body fluid (SBF 5) showed rapid mineralization within 24h due to the increased wettability in fine grained AZ31 Mg alloy. Corrosion behavior of the samples assessed by weight loss and electrochemical tests conducted in SBF 5 clearly showed the prominent role of enhanced mineral deposition on ECAPed AZ31 Mg in controlling the abnormal degradation. Cytotoxicity studies by MTT colorimetric assay showed that all the samples are viable. Additionally, cell adhesion was excellent for ECAPed samples particularly for the 3rd and 4th pass samples. In vivo experiments conducted using New Zealand White rabbits clearly showed lower degradation rate for ECAPed sample compared with annealed AZ31 Mg alloy and all the samples showed biocompatibility and no health abnormalities were noticed in the animals after 60days of in vivo studies. These results suggest that the grain size plays an important role in degradation management of magnesium alloys and ECAP technique can be adopted to achieve fine grain structures for developing degradable magnesium alloys for biomedical applications. PMID:26652384

  18. Post-heat Treatment Effects on Cold-Sprayed Aluminum Coatings on AZ91D Magnesium Substrates

    NASA Astrophysics Data System (ADS)

    Bu, Hengyong; Yandouzi, Mohammed; Lu, Chen; Jodoin, Bertrand

    2012-06-01

    Commercially pure aluminum (CP-Al) powder was deposited by the cold spray process onto AZ91D magnesium (Mg) substrates that had been subjected to three different heat-treatment conditions: namely, as-cast (F), homogenized (T4), and artificially aged (T6). The substrate hardness was measured to be 80.7 1.8, 73.7 4.0, and 103.6 7.4 HV0.025 for the F-, T4-, and T6-Mg alloy substrates respectively. Thick (~400 ?m) and dense (below 1% porosity) Al coatings have been obtained. After post-deposition heat treatment at 400 C, the intermetallic Mg17Al12 (?) and Al3Mg2 (?) phases with different thicknesses were found to have formed at the coating/substrate interface depending on the holding time. While no significant thickness differences of the intermetallic layers were detected in the cases of F- and T6-AZ91D substrates, thicker layers formed on the T4-AZ91D substrate. It is believed that the higher Al concentration in the T4-AZ91D solid solution within the ?-Mg could diffuse and contribute more easily to the growth of the intermetallic phases. The hardness of the ?- and ?-phase was measured to be 260.5 10.7 HV0.025 and 279.6 13.7 HV0.025, respectively. Shear strength test results revealed lower adhesion strength after heat treatment, which is attributed to the presence of brittle intermetallic layers at the coating/substrate interface.

  19. 241-AZ-101 Mixer Pump Demonstration Test Gamma Cart Acceptance Test Procedure and Quality Test Plan (ATP and QTP)

    SciTech Connect

    WHITE, D.A.

    2000-01-27

    Shop test of the sludge mobilization cart system to be used in the AZ-101 Mixer Pump Demonstration Test Tests hardware and software. This procedure involves testing the Instrumentation involved with the Gamma Cart System, local and remote, including depth indicators, speed controls, interface to data acquisition software and the raising and lowering functions. This Procedure will be performed twice, once for each Gamma Cart System. This procedure does not test the accuracy of the data acquisition software.

  20. In vitro degradation, hemolysis, and cytocompatibility of PEO/PLLA composite coating on biodegradable AZ31 alloy.

    PubMed

    Wei, Zhongling; Tian, Peng; Liu, Xuanyong; Zhou, Bangxin

    2015-02-01

    Magnesium and its alloys have large potential as degradable and absorbable biomaterials because of their mechanical properties and biocompatibility. However, their corrosion resistance is usually inadequate especially in physiological environment, which limits their broad applications in biomedical areas. In this work, plasma electrolytic oxidized/poly(l-lactide) (PEO/PLLA) composite coating was successfully fabricated on biodegradable AZ31 alloy by combing PEO process and sealing with PLLA. The microstructure, elemental composition, and phase composition of the PEO/PLLA composite coating were investigated. The in vitro degradation of the PEO/PLLA composite coating in simulated body fluid (SBF) was also systematically evaluated. The results revealed that the PEO/PLLA composite coating improved the corrosion resistance of AZ31 alloy significantly. The corrosion potential shifted from -1.663V to more positive position -1.317 V and the corrosion current density was reduced with six-order of magnitude. The Mg(2+) ions, hydrogen release, and pH value change of solution caused by degradation were all decreased significantly. Moreover, the PEO process played a critical role in sustaining the integrity of the implant in long-term service. The result of hemolysis test showed that the PEO/PLLA composite coating vested AZ31 alloy a low hemolysis ratio (0.806??0.771)%, which is much lower than the safe value of 5% according to ISO 10993-4. For the cytocompatibility test, compared with bare AZ31 alloy and PEO coating, MC3T3-E1 cells showed much better adhesion and proliferation on the PEO/PLLA composite coating with nearly 4-fold increase of cells after 7-day cultivation, indicating that the PEO/PLLA composite coating has good biocompatibility for biomedical applications. PMID:24889920

  1. Effect of hot working on the damping capacity and mechanical properties of AZ31 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Lee, K.; Kang, C.; Kim, K.

    2015-04-01

    Magnesium alloys have received much attention for their lightweight and other excellent properties, such as low density, high specific strength, and good castability, for use in several industrial and commercial applications. However, both magnesium and its alloys show limited room-temperature formability owing to the limited number of slip systems associated with their hexagonal close-packed crystal structure. It is well known that crystallographic texture plays an important role in both plastic deformation and macroscopic anisotropy of magnesium alloys. Many authors have concentrated on improving the room- temperature formability of Mg alloys. However, despite having a lot of excellent properties in magnesium alloy, the study for various properties of magnesium alloy have not been clarified enough yet. Mg alloys are known to have a good damping capacity compared to other known metals and their alloys. Also, the damping properties of metals are generally recognized to be dependent on microstructural factors such as grain size and texture. However, there are very few studies on the relationship between the damping capacity and texture of Magnesium alloys. Therefore, in this study, specimens of the AZ31 magnesium alloy, were processed by hot working, and their texture and damping property investigated. A 60 mm × 60 mm × 40 mm rectangular plate was cut out by machining an ingot of AZ31 magnesium alloy (Mg-3Al-1Zn in mass%), and rolling was carried out at 673 K to a rolling reduction of 30%. Then, heat treatment was carried out at temperatures in the range of 573-723 K for durations in the range of 30-180 min. The samples were immediately quenched in oil after heat treatment to prevent any change in the microstructure. Texture was evaluated on the compression planes by the Schulz reflection method using nickel-filtered Cu Kα radiation. Electron backscatter diffraction measurements were conducted to observe the spatial distribution of various orientations. Specimens for damping capacity measurements were machined from the rolled specimen, to have a length of 120 mm, width of 20 mm, and thickness of 1 mm. The damping capacity was measured with a flexural internal friction measurement machine at room temperature. It was found that the damping capacity increases with both increasing heat-treatment temperature and time, due to grain growth and the increased pole densities of textures.

  2. Msc1 Acts Through Histone H2A.Z to Promote Chromosome Stability in Schizosaccharomyces pombe

    PubMed Central

    Ahmed, Shakil; Dul, Barbara; Qiu, Xinxing; Walworth, Nancy C.

    2007-01-01

    As a central component of the DNA damage checkpoint pathway, the conserved protein kinase Chk1 mediates cell cycle progression when DNA damage is generated. Msc1 was identified as a multicopy suppressor capable of facilitating survival in response to DNA damage of cells mutant for chk1. We demonstrate that loss of msc1 function results in an increased rate of chromosome loss and that an msc1 null allele exhibits genetic interactions with mutants in key kinetochore components. Multicopy expression of msc1 robustly suppresses a temperature-sensitive mutant (cnp1-1) in the centromere-specific histone H3 variant CENP-A, and localization of CENP-A to the centromere is compromised in msc1 null cells. We present several lines of evidence to suggest that Msc1 carries out its function through the histone H2A variant H2A.Z, encoded by pht1 in fission yeast. Like an msc1 mutant, a pht1 mutant also exhibits chromosome instability and genetic interactions with kinetochore mutants. Suppression of cnp1-1 by multicopy msc1 requires pht1. Likewise, suppression of the DNA damage sensitivity of a chk1 mutant by multicopy msc1 also requires pht1. We present the first genetic evidence that histone H2A.Z may participate in centromere function in fission yeast and propose that Msc1 acts through H2A.Z to promote chromosome stability and cell survival following DNA damage. PMID:17947424

  3. Laser surface forming of AlCoCrCuFeNi particle reinforced AZ91D matrix composites

    NASA Astrophysics Data System (ADS)

    Meng, Guanghui; Yue, T. M.; Lin, Xin; Yang, Haiou; Xie, Hui; Ding, Xu

    2015-07-01

    Traditionally, the laser melt injection (LMI) technique can only be used for forming ceramic particles reinforced metal matrix composites (MMCs) for enhancing surface properties of lightweight engineering materials. In this research, the LMI method was employed to form metal particles reinforced MMCs on AZ91D instead. This was viable because of the unique properties of the AlCoCrCuFeNi high-entropy alloy (HEA) metal particles used. The large difference in melting point between the HEA and the substrate material (AZ91D), and the limited reaction and the lack of fusion between the HEA and Mg have made it possible that a metal particles reinforced AZ91D composite material was produced. The reason of limited reaction was considered mainly due to the relatively high mixing enthalpy between the HEA constituent elements and Mg. Although there was some melting occurred at the particles surface with some solute segregation found in the vicinity close to the surface, intermetallic compounds were not observed. With regard to the wear resistance of the MMCs, it was found that when the volume fraction of the reinforcement phase, i.e. the HEA particles, reached about 0.4, the wear volume loss of the coating was only one-seventh of that of the substrate material.

  4. Development of a Binary Zn-Based Solder Alloy for Joining Wrought Magnesium Alloy AZ31B

    NASA Astrophysics Data System (ADS)

    Ma, Li; Long, Weimin; Qiao, Peixin; He, Dingyong; Li, Xiaoyan

    2013-01-01

    In the present article, the wrought magnesium alloy AZ31B sheets were soldered by means of high-frequency induction heating device using a novel binary Zn-based solder alloy in argon gas shield condition. The interfacial microstructure, phase constitution, and fracture morphology of the soldered joint were studied. The microhardness and shear strength of the soldered joint were tested. The experimental results exhibit that α-Mg solid solution and γ-MgZn phase were formed in soldering region. Moreover, the β-Mg7Zn3 phase in the original Zn-based solder alloy disappeared completely after the soldering process due to the fierce alloying between the molten binary Zn-based solder alloy and the base metal AZ31B during soldering. Test results show that the shear strength of the soldered joint is 28 MPa. The fracture morphology of the soldered joint displays an intergranular fracture mode, and the crack originates from α-Mg + γ-MgZn eutectoid structure. The interaction between the molten Zn-based solder alloy and the base metal AZ31B leads the Zn-based solder alloy to be transformed into Mg-based soldering metal during soldering.

  5. New LMT High Resolution Imaging and CO Spectroscopic Studies of the Brightest AzTEC 1.1mm Sources

    NASA Astrophysics Data System (ADS)

    Yun, Min S.; Aretxaga, Itziar; Hughes, David; Montana, A.; Pope, A.; Bruzual, Gustavo; Ferrusca, D.; Rosa Gonzalez, D.; Sanchez-Arguelles, D.; Narayanan, G.; Wilson, Grant; Gim, Hansung; Ibarra, H.; Mo, H.; Lowenthal, James; Zavala, J.; Carrasco, L.; Chavez, M.; Valazquez, M.; Zeballos, M.; Vega, O.; Schloerb, P.; Cybulsky, J. R.; Casey, Caitlin M.; Tang, Y.

    2015-08-01

    A substantial population of quiescent galaxies with stellar masses exceeding 10 billion solar masses have been found to z~4, suggesting a rapid formation and quenching of massive galaxies at z~6 or earlier. The submillimeter bright galaxies (SMGs) with SFR > 100-1000 solar masses per year represent natural candidates for the progenitor systems undergoing an epoch of rapid formation and cessation of stellar mass build up. Many of the most luminous SMGs are also extremely red and faint in the optical, suggesting a high redshift and are beyond the reach of the current optical spectroscopic redshift surveys. There is also a growing concern that these most luminous SMGs may be blends of several unrelated sources as a result of a poor angular resolution of the existing surveys (18" & 28" for the AzTEC 1.1mm surveys on JCMT and ASTE, respectively). We have obtained new 8" resolution AzTEC images of 40 brightest AzTEC sources previously found in the GOODS and COSMOS fields using the Large Millimeter Telescope (LMT) to examine the multiplicity question and for the identification of multi-wavelength counterparts. We have also conducted a CO redshift survey using the Redshift Search Receiver on the LMT. We will report the results of these analysis and several new CO redshifts.

  6. Corrosion fatigue behaviors of two biomedical Mg alloys - AZ91D and WE43 - In simulated body fluid.

    PubMed

    Gu, X N; Zhou, W R; Zheng, Y F; Cheng, Y; Wei, S C; Zhong, S P; Xi, T F; Chen, L J

    2010-12-01

    Magnesium alloys have been recently developed as biodegradable implant materials, yet there has been no study concerning their corrosion fatigue properties under cyclic loading. In this study the die-cast AZ91D (A for aluminum 9%, Z for zinc 1% and D for a fourth phase) and extruded WE43 (W for yttrium 4%, E for rare earth mischmetal 3%) alloys were chosen to evaluate their fatigue and corrosion fatigue behaviors in simulated body fluid (SBF). The die-cast AZ91D alloy indicated a fatigue limit of 50MPa at 10? cycles in air compared to 20MPa at 10? cycles tested in SBF at 37C. A fatigue limit of 110MPa at 10? cycles in air was observed for extruded WE43 alloy compared to 40MPa at 10? cycles tested in SBF at 37C. The fatigue cracks initiated from the micropores when tested in air and from corrosion pits when tested in SBF, respectively. The overload zone of the extruded WE43 alloy exhibited a ductile fracture mode with deep dimples, in comparison to a brittle fracture mode for the die-cast AZ91D. The corrosion rate of the two experimental alloys increased under cyclic loading compared to that in the static immersion test. PMID:20656074

  7. Deposition of histone H2A.Z by the SWR-C remodeling enzyme prevents genome instability.

    PubMed

    Van, Christopher; Williams, Jessica S; Kunkel, Thomas A; Peterson, Craig L

    2015-01-01

    The yeast SWR-C chromatin remodeling enzyme catalyzes chromatin incorporation of the histone variant H2A.Z which plays roles in transcription, DNA repair, and chromosome segregation. Dynamic incorporation of H2A.Z by SWR-C also enhances the ability of exonuclease I (Exo1) to process DNA ends during repair of double strand breaks. Given that Exo1 also participates in DNA replication and mismatch repair, here we test whether SWR-C influences DNA replication fidelity. We find that inactivation of SWR-C elevates the spontaneous mutation rate of a strain encoding a L612M variant of DNA polymerase (Pol) ?, with a single base mutation signature characteristic of lagging strand replication errors. However, this genomic instability does not solely result from reduced Exo1 function, because single base mutator effects are seen in both Exo1-proficient and Exo1-deficient pol3-L612M swr1? strains. The data are consistent with the possibility that incorporation of the H2A.Z variant by SWR-C may stimulate Exo1 activity, as well as enhance the fidelity of replication by Pol ?, the repair of mismatches generated by Pol ?, or both. PMID:25463393

  8. Influence of shot peening on corrosion properties of biocompatible magnesium alloy AZ31 coated by dicalcium phosphate dihydrate (DCPD).

    PubMed

    Mhaede, Mansour; Pastorek, Filip; Hadzima, Branislav

    2014-06-01

    Magnesium alloys are promising materials for biomedical applications because of many outstanding properties like biodegradation, bioactivity and their specific density and Young's modulus are closer to bone than the commonly used metallic implant materials. Unfortunately their fatigue properties and low corrosion resistance negatively influenced their application possibilities in the field of biomedicine. These problems could be diminished through appropriate surface treatments. This study evaluates the influence of a surface pre-treatment by shot peening and shot peening+coating on the corrosion properties of magnesium alloy AZ31. The dicalcium phosphate dihydrate coating (DCPD) was electrochemically deposited in a solution containing 0.1M Ca(NO3)2, 0.06M NH4H2PO4 and 10mL/L of H2O2. The effect of shot peening on the surface properties of magnesium alloy was evaluated by microhardness and surface roughness measurements. The influence of the shot peening and dicalcium phosphate dihydrate layer on the electrochemical characteristics of AZ31 magnesium alloy was evaluated by potentiodynamic measurements and electrochemical impedance spectroscopy in 0.9% NaCl solution at a temperature of 221C. The obtained results were analyzed by the Tafel-extrapolation method and equivalent circuit method. The results showed that the application of shot peening process followed by DCPD coating improves the properties of the AZ31 surface from corrosion and mechanical point of view. PMID:24863232

  9. Textures and Microstructures Formed in WE43 and AZ31 Magnesium Alloys during High Speed Rolling and Their Formation Mechanisms

    NASA Astrophysics Data System (ADS)

    Onuki, Y.; Hara, K.; Utsunomiya, H.; Szpunar, J. A.

    2015-04-01

    High speed rolling is recognized as the process that can produce sheets of magnesium alloys having RD-split basal texture without or with minimum preheating. However, the mechanism of the texture formation during high speed rolling has not been fully clarified yet. In this study, conventional AZ31 and a rare earth - yttrium added alloy, WE43 were rolled with high rolling speed. The specimens having different textures were prepared by changing the cutting geometry to initially textured sheets. It is seen that the crack, microstructure and texture formations are strongly influenced by the initial textures in AZ31. These features are strongly related to the extension twinning, {10-12}<-1011>. In the case of WE43, cracks are formed more often than in AZ31, despite of the weak initial textures. It is proposed that the activities of the contraction and double twinning systems give more chance of stress concentration, resulting in the narrow shear banding and subsequent cracking. In addition to the experimental analysis, results of the numerical simulation using VPSC model are also used to discuss the texture formation mechanism.

  10. Influence of Tension-Compression Asymmetry on the Mechanical Behavior of AZ31B Magnesium Alloy Sheets in Bending

    NASA Astrophysics Data System (ADS)

    Zhou, Ping; Beeh, Elmar; Friedrich, Horst E.

    2016-02-01

    Magnesium alloys are promising materials for lightweight design in the automotive industry due to their high strength-to-mass ratio. This study aims to study the influence of tension-compression asymmetry on the radius of curvature and energy absorption capacity of AZ31B-O magnesium alloy sheets in bending. The mechanical properties were characterized using tension, compression, and three-point bending tests. The material exhibits significant tension-compression asymmetry in terms of strength and strain hardening rate due to extension twinning in compression. The compressive yield strength is much lower than the tensile yield strength, while the strain hardening rate is much higher in compression. Furthermore, the tension-compression asymmetry in terms of r value (Lankford value) was also observed. The r value in tension is much higher than that in compression. The bending results indicate that the AZ31B-O sheet can outperform steel and aluminum sheets in terms of specific energy absorption in bending mainly due to its low density. In addition, the AZ31B-O sheet was deformed with a larger radius of curvature than the steel and aluminum sheets, which brings a benefit to energy absorption capacity. Finally, finite element simulation for three-point bending was performed using LS-DYNA and the results confirmed that the larger radius of curvature of a magnesium specimen is mainly attributed to the high strain hardening rate in compression.

  11. Producing Nanocomposite Layer on the Surface of As-Cast AZ91 Magnesium Alloy by Friction Stir Processing

    NASA Astrophysics Data System (ADS)

    Asadi, P.; Besharati Givi, M. K.; Faraji, G.

    Friction stir processing (FSP) is an effective tool to produce a surface composite layer with enhanced mechanical properties and modified microstructure of as-cast and sheet metals. In the present work, the mechanical and microstructural properties of as-cast AZ91 magnesium alloy were enhanced by FSP and an AZ91/SiC surface nanocomposite layer has been produced using 30 nm SiC particles. Effect of the FSP pass number on the microstructure, grain size, microhardness, and powder distributing pattern of the surface developed has been investigated. The developed surface nanocomposite layer presents a higher hardness, an ultra fine grain size and a better homogeneity. Results show that, increasing the number of FSP passes enhances distribution of nano-sized SiC particles in the AZ91 matrix, decreases the grain size, and increases the hardness significantly. Also, changing of the tool rotating direction results much uniform distribution of the SiC particles, finer grains, and a little higher hardness.

  12. Early Science with the Large Millimeter Telescope: CO and [C II] Emission in the z = 4.3 AzTEC J095942.9+022938 (COSMOS AzTEC-1)

    NASA Astrophysics Data System (ADS)

    Yun, Min S.; Aretxaga, I.; Gurwell, M. A.; Hughes, D. H.; Montaña, A.; Narayanan, G.; Rosa-González, D.; Sánchez-Argüelles, D.; Schloerb, F. P.; Snell, R. L.; Vega, O.; Wilson, G. W.; Zeballos, M.; Chavez, M.; Cybulski, R.; Díaz-Santos, T.; De La Luz, V.; Erickson, N.; Ferrusca, D.; Gim, H. B.; Heyer, M. H.; Iono, D.; Pope, A.; Rogstad, S. M.; Scott, K. S.; Souccar, K.; Terlevich, E.; Terlevich, R.; Wilner, D.; Zavala, J. A.

    2015-12-01

    Measuring redshifted CO line emission is an unambiguous method for obtaining an accurate redshift and total cold gas content of optically faint, dusty starburst systems. Here, we report the first successful spectroscopic redshift determination of AzTEC J095942.9+022938 (`COSMOS AzTEC-1'), the brightest 1.1 mm continuum source found in the AzTEC/James Clerk Maxwell Telescope survey (Scott et al.), through a clear detection of the redshifted CO (4-3) and CO (5-4) lines using the Redshift Search Receiver on the Large Millimeter Telescope. The CO redshift of z = 4.3420 ± 0.0004 is confirmed by the detection of the redshifted 158 μm [C II] line using the Submillimeter Array. The new redshift and Herschel photometry yield LFIR = (1.1 ± 0.1) × 1013 L⊙ and SFR ≈ 1300 M⊙ yr-1. Its molecular gas mass derived using the ultraluminous infrared galaxy conversion factor is 1.4 ± 0.2 × 1011M⊙ while the total interstellar medium mass derived from the 1.1 mm dust continuum is 3.7 ± 0.7 × 1011M⊙ assuming Td = 35 K. Our dynamical mass analysis suggests that the compact gas disc (r ≈ 1.1 kpc, inferred from dust continuum and spectral energy distribution analysis) has to be nearly face-on, providing a natural explanation for the uncommonly bright, compact stellar light seen by the HST. The [C II] line luminosity L_[C II]= 7.8± 1.1 × 10^9 L_{⊙} is remarkably high, but it is only 0.04 per cent of the total IR luminosity. AzTEC COSMOS-1 and other high redshift sources with a spatially resolved size extend the tight trend seen between [C II]/FIR ratio and ΣFIR among IR-bright galaxies reported by Díaz-Santos et al. by more than an order of magnitude, supporting the explanation that the higher intensity of the IR radiation field is responsible for the `[C II] deficiency' seen among luminous starburst galaxies.

  13. Rapid City, SD Showcase Streamgage

    USGS Multimedia Gallery

    A USGS South Dakota Water Science Center streamgage was dedicated by Congressional and city officials on September 3 in Rapid City. This showcase streamgage is located onRapid Creek at Rapid Cityin Founders Park and provides visitors with critical information about how streamflow is meas...

  14. New York City's Education Battles

    ERIC Educational Resources Information Center

    Meyer, Peter

    2008-01-01

    When Bloomberg gave his first State of the City address, in January, 2002, he announced his intention to seek mayoral control of the schools and abolish the infamous New York City Board of Education, which he called "a rinky-dink candy store." He joined a long list of New York mayors, educators, and business leaders who believed that the city's

  15. Rapid City, SD Showcase Streamgage

    USGS Multimedia Gallery

    A USGS South Dakota Water Science Center streamgage was dedicated by Congressional and city officials on September 3 in Rapid City. This showcase streamgage is located on Rapid Creek at Rapid City in Founders Park and provides visitors with critical information about how streamflow is meas...

  16. The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents.

    PubMed

    Zhang, Yaowu; Kent, Damon; Wang, Gui; StJohn, David; Dargusch, Matthew S

    2014-11-01

    Mg alloys are receiving considerable attention for biomedical stents due to their combination of good mechanical properties and high biodegradability. Cold rolling is necessary to process Mg alloy tubes before final drawing and fabrication of the magnesium stents. In this paper, cold-rolled tubes were subjected to a cross-sectional reduction rate (ε) of up to 19.7%, and were further processed at various ratios of wall-thickness to diameter reduction (Q) from 0 to 2.24 with a constant ε of 19.7%. The results show that the cold-rolled tubes exhibited a rise in ultimate tensile strength (UTS), yield strength (YS), and a reduction in elongation as ε increased from 5.5% to 19.7%. UTS, YS and elongation decreased when Q was increased from 0 to 2.24. Mechanical twinning was observed and analysed. Extension twins increased with increasing ε and were almost saturated at a ε of 16.5%. Extension twins play an important role in determining the evolution of mechanical behaviour in the case of increasing ε, whilst contraction/double twins and secondary extension twins have a large effect on mechanical behaviour in the case of varying Q. The results indicate that the proportions and types of twins play a major role in determining the mechanical behaviour of the AZ31 tubes. PMID:25171746

  17. New Az/El mount for Haystack Observatory's Small Radio Telescope kit

    NASA Astrophysics Data System (ADS)

    Cobb, M. L.

    2005-12-01

    The Small Radio Telescope (SRT) kit was designed by Haystack Observatory as part of their educational outreach effort. The SRT uses a custom designed FFT based radio spectrometer receiver with a controller to position a 2.3m dish to make various radio astronomy observations including the 21 cm spin flip line of atomic hydrogen. Because there is no sizable commercial market for a two dimensional mount for dishes of this size, finding an appropriate provider as been a recurring problem for the project. Originally, the kit used a modified motor mount from Kaultronics called the H180. Two of these motors were combined by a specially designed adaptor to allow motion in azimuth and elevation. When Kaultronics was bought out by California Amplifier they discontinued production of the H180. The next iteration used a compact unit called the alfa-spid which was made in Germany and imported through Canada. The alfa-spid was designed to point various ham radio antennas and proved problematic with 2.3m dishes. Most recently the CASSI (Custom Astronomical Support Services, Inc.) corporation has designed and certified a robust Az/El mount capable of supporting dishes up to 12 feet (3.6m) with 100 MPH wind loads. This paper presents the design and operating characteristics of the new CASSI mount. The CASSI mount is now shipped with the SRT kit and should serve the project well for the foreseeable future.

  18. Quantifying texture evolution during hot rolling of AZ31 Twin Roll Cast strip

    NASA Astrophysics Data System (ADS)

    Gorelova, S.; Schaeben, H.

    2015-04-01

    Multi-pass rolling experiments with an AZ31 Twin Roll Cast (TRC) alloy were performed on an industrial scaled four-high rolling mill. Within the rolling with an intermediate annealing the evolution of texture was investigated. To quantify the extent of preferred crystallographic orientation experimental X-ray pole figures were measured after different process steps and analyzed using the free and open Matlab toolbox MTEX for texture analysis. The development of the fiber texture was observed and analyzed in dependence on rolling conditions. In the initial state the specimen exhibits a texture composed of a weak basal texture and a cast texture with {0001}-planes oriented across the rolling direction. During the following rolling process a fiber texture was developed. The expected strength increment of the fiber texture was quantitatively confirmed in terms of volume portions of the orientation density function around the fiber and in terms of the canonical parameters of fitted pseudo Bingham distributions. On the results of this work a model for prediction of the texture evolution during the strip rolling of magnesium in the examined parameter range was developed.

  19. Recycling of AZ40 Magnesium Alloy Scraps by Hydriding-Dehydriding and Subsequent Consolidation Processing

    NASA Astrophysics Data System (ADS)

    Haiping, Zhou; Lianxi, Hu; Yu, Sun; Heng, Wang

    2015-09-01

    The hydriding-dehydriding process was used to recycle AZ40 magnesium (Mg) alloy scraps, and the microstructure nanocrystallization was realized. X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy were carried out to characterize the microstructure. After mechanically milling in hydrogen for 72 h, matrix Mg was completely turned into nanocrystalline MgH2, with an average crystallite size of about 10 nm. And then, the MgH2 phase was completely transformed into Mg again through vacuum dehydriding treatment at 300 C for 192 min, with an average crystallite size of about 20 nm. In addition, the nanocrystalline alloy powders were hot-pressed and extruded into bars. The average grain size of the bars was about 500 nm, which had reached the size of ultrafine-grain. Meanwhile, the yield strength and ultimate tensile strength of the as-extruded bars reached about 312 and 497 MPa, respectively. The results indicate that hydriding-dehydriding process is a feasible method for recycling of Mg alloy scraps, and it is expected to have a good application prospect in preparing ultrafine-grain Mg alloys.

  20. THE AzTEC/SMA INTERFEROMETRIC IMAGING SURVEY OF SUBMILLIMETER-SELECTED HIGH-REDSHIFT GALAXIES

    SciTech Connect

    Younger, Joshua D.; Fazio, Giovanni G.; Huang Jiasheng; Ashby, Matthew L. N.; Gurwell, Mark A.; Petitpas, Glen R.; Wilner, David J.; Yun, Min S.; Wilson, Grant W.; Scott, Kimberly S.; Austermann, Jason; Perera, Thushara; Peck, Alison B.; Hughes, David H.; Aretxaga, Itziar; Kim, Sungeun; Lowenthal, James D.

    2009-10-10

    We present results from a continuing interferometric survey of high-redshift submillimeter galaxies (SMGs) with the Submillimeter Array, including high-resolution (beam size approx2 arcsec) imaging of eight additional AzTEC 1.1 mm selected sources in the COSMOS field, for which we obtain six reliable (peak signal-to-noise ratio (S/N) >5 or peak S/N >4 with multiwavelength counterparts within the beam) and two moderate significance (peak S/N >4) detections. When combined with previous detections, this yields an unbiased sample of millimeter-selected SMGs with complete interferometric follow up. With this sample in hand, we (1) empirically confirm the radio-submillimeter association, (2) examine the submillimeter morphology-including the nature of SMGs with multiple radio counterparts and constraints on the physical scale of the far infrared-of the sample, and (3) find additional evidence for a population of extremely luminous, radio-dim SMGs that peaks at higher redshift than previous, radio-selected samples. In particular, the presence of such a population of high-redshift sources has important consequences for models of galaxy formation-which struggle to account for such objects even under liberal assumptions-and dust production models given the limited time since the big bang.