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Sample records for bullhead city az

  1. 77 FR 36439 - Safety Zone; Bullhead City Regatta; Bullhead City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-19

    ... 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 11, 2012. 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

    ... 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 10, 2013. This temporary safety zone is necessary to provide for the...

  3. 78 FR 44011 - Safety Zone; Bullhead City Regatta; Bullhead City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-23

    ... 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 10, 2013. This temporary safety zone is necessary to provide for the...

  4. 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...

  5. 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

    ... River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam (Parker, Arizona). 100.1102 Section... Davis Dam (Bullhead City, Arizona) and Headgate Dam (Parker, Arizona). (a) General. Sponsors are... Roadrunner Resort and Headgate Dam). Bullhead City Boat Drags Sponsor: Sunshine Promotions Date: 2 to...

  6. 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

    ... Colorado River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam (Parker, Arizona) within the... § 100.1102 Annual marine events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and.... Regulated Area That portion of the lower Colorado River on the Arizona side between Thompson Bay and...

  7. 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

    ... Colorado River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam (Parker, Arizona) within the... § 165.1124 Annual Firework Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and... 8 p.m.-10 p.m. The safety zone includes all navigable waters of the lower Colorado River at...

  8. 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

    ... Colorado River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam (Parker, Arizona) within the... § 165.1124 Annual Firework Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and... 8pm-10pm. The safety zone includes all navigable waters of the lower Colorado River at Laughlin,...

  9. 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

    ... Colorado River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam (Parker, Arizona) within the... § 165.1124 Annual Firework Events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and... 8pm-10pm. The safety zone includes all navigable waters of the lower Colorado River at Laughlin,...

  10. 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

    ... Colorado River, between Davis Dam (Bullhead City, Arizona) and Headgate Dam (Parker, Arizona) within the... § 100.1102 Annual marine events on the Colorado River, between Davis Dam (Bullhead City, Arizona) and.... Regulated Area That portion of the lower Colorado River on the Arizona side between Thompson Bay and...

  11. 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...

  12. 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...

  13. 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, between Davis Dam (Bullhead City, Arizona) and Headgate Dam (Parker, Arizona). 100.1102... MARINE PARADES SAFETY OF LIFE ON NAVIGABLE WATERS § 100.1102 Annual Marine Events on the Colorado River... portion of the lower Colorado River on the Arizona side between Thompson Bay and Copper Canyon. 2....

  14. 78 FR 48303 - Establishment of Class E Airspace; Tuba City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-08

    ... TRANSPORTATION Federal Aviation Administration 14 CFR Parts 71 Establishment of Class E Airspace; Tuba City, AZ... airspace at the Tuba City VHF Omni-Directional Radio Range Tactical Air Navigational Aid (VORTAC), Tuba City, AZ. In that rule, an error was made in the legal description for Tuba City, identifying...

  15. 78 FR 32086 - Establishment of Class E Airspace; Tuba City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-29

    ... airspace at the Tuba City VHF Omni-Directional Radio Range Tactical Air Navigational Aid (VORTAC), Tuba City, AZ, to facilitate vectoring of Instrument Flight Rules (IFR) aircraft under control of Denver..., at the Tuba City VORTAC, Tuba City, AZ. This action aids in containing aircraft while in...

  16. 78 FR 17097 - Safety Zone; Lake Havasu Triathlon; Lake Havasu City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-20

    ... From the Federal Register Online via the Government Publishing Office ] DEPARTMENT OF HOMELAND SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Havasu Triathlon; Lake Havasu City, AZ.... 165.T11-474 to read as follows: Sec. 165.T11-474 Safety Zone; Lake Havasu Triathlon; Lake Havasu...

  17. 78 FR 16823 - Proposed Establishment of Class E Airspace; Tuba City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-19

    ...: This action proposes to establish Class E airspace at the Tuba City VHF Omni-Directional Radio Range... (IFR) aircraft under control of Denver, Albuquerque and Salt Lake City Air Route Traffic Control Centers (ARTCCs). The FAA is proposing this action to enhance the safety and management of...

  18. 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 ...

  19. 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...

  20. 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

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone, Lucas Oil Drag Boat Racing Series; Thompson... Guard is establishing a temporary safety zone within the navigable waters of Thompson Bay in Lake Havasu... Thompson Bay, Lake Havasu, AZ for The Lucas Oil Drag Boat Racing Series. This safety zone is necessary...

  1. Temperature-dependent Index of Mitotic Interval (τ0) for Chromosome Manipulation in Korean Bullhead, Pseudobagrus fulvidraco.

    PubMed

    Lim, Sang Gu; Han, Hyoung Kyun; Gil, Hyun Woo; Park, In-Seok

    2012-12-01

    Korean bullhead (Pseudobagrus fulvidraco) was collected from the Kum River areas of Kangkyung-eup, Nonsan city, Chungcheongnam-do, Korea, from April to June, 2012 and was fertilized in order to observe egg development and temperature-related cleavage rates and mitotic intervals (τ0). The fertilized eggs were separative, demersal and light yellowish with 1.5±0.06 mm in diameter, and did not contain oil globules. The first cleavage stages were 90 min, 80 min, 60 min and 50 min at 21°C , 24°C , 27°C and 30°C , respectively. At higher temperatures, eggs developed faster and underwent further identical development. For Korean bullhead, τ0 were 33.4±2.08 min at 21°C, 31.5±3.06 min at 24°C, 28.1±2.11 min at 27°C and 26.4±3.35 min at 30°C . There were strong negative correlations between the τ0 and water temperatures at all points studied (Y= 1.13X+58.15, R (2)=0.98, n=30, where Y is τ0 and X is temperature). The results obtained in this work will be helpful for chromosome manipulation by use of cleavage frequency data and τ0 data in Korean bullhead.

  2. 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

    ... future noise contours. Arrival and departure flight tracks for the existing and five-year forecast Noise... noise exposure contours depicted on a noise exposure map submitted under section 47503 of the Act, it... properties with regard to the depicted noise contours, or in interpreting the noise exposure maps to...

  3. 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.

  4. 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, ...

  5. Comparative metabolism of benzo[a]pyrene by liver microsomes of channel catfish and brown bullhead

    SciTech Connect

    Yuan, Z.X.; Kumar, S.; Sikka, H.C.

    1997-04-01

    The authors investigated the metabolism of the carcinogen benzo[a]pyrene (BaP) by liver microsomes of channel catfish (Ictalurus punctatus) and brown bullhead (Ameiurus nebulosus) pretreated with 3-methylcholanthrene. The catfish liver microsomes metabolized BaP at a considerably lower rate than did the brown bullhead liver microsomes. Although the BaP metabolites produced by the liver microsomes of the two species were qualitatively similar, there were considerable differences in the relative proportions of individual metabolites formed. The catfish liver microsomes produced a considerably lower proportion of benzo-ring diols of BaP including BaP-7,8-diol (the proximate carcinogenic metabolite of BaP) than did the bullhead liver microsomes. Compared to the bullhead liver microsomes, the catfish microsomes converted a higher proportion of BaP to phenolic metabolites.

  6. 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

  7. 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

  8. Variable growth and longevity of yellow bullhead (Ameiurus natalis) in the Everglades of south Florida, USA

    USGS Publications Warehouse

    Murie, D.J.; Parkyn, D.C.; Loftus, W.F.; Nico, L.G.

    2009-01-01

    Yellow bullhead (Ictaluridae: Ameiurus natalis) is the most abundant ictalurid catfish in the Everglades of southern Florida, USA, and, as both prey and predator, is one of many essential components in the ecological-simulation models used in assessing restoration success in the Everglades. Little is known of its biology and life history in this southernmost portion of its native range; the present study provides the first estimates of age and growth from the Everglades. In total, 144 yellow bullheads of 97-312 mm total length (TL) were collected from canals and marshes of the Everglades between April 2000 and January 2001, and from October 2003 to February 2005. Fish were aged using cross-sections of pectoral spines and ranged from 1-12 years, with the maximum age almost twice that of any yellow bullhead previously reported. Yellow bullheads from south Florida grew relatively rapidly during their first 3 years, but after age 5 growth slowed and fish approached an asymptote of ???214 mm TL. Compared to other populations in the United States, yellow bullhead in the Everglades grew relatively slowly, were smaller at age overall, but survived to older ages. ?? 2009 Blackwell Verlag GmbH.

  9. The effect of contaminated sediments on fecundity of the brown bullhead in three Lake Erie tributaries

    USGS Publications Warehouse

    Lesko, Lynn T.; Smith, Stephen B.; Blouin, Marc A.

    1996-01-01

    Female brown bullhead (Ameiurus nebulosus) were collected from three Lake Erie tributaries (Ohio) from 8 to 25 May 1989, to determine the effects of contaminated sediments on reproductive potentials. Fish obtained from the Black and Cuyahoga rivers, which contain sediments with elevated concentrations of metals, PCBs, and PAHs, were compared with fish collected in Mud Brook, a tributary of the Huron River, which was selected as our reference site. Fecundity, egg diameter, fish length and weight, and the presence of external abnormalities were recorded for each fish. Brown bullhead from the contaminated sites were larger then those from the reference site and fecundity was significantly (P < 0.05) different in all three river systems. Those from the most polluted river (Cuyahoga River) had the greatest number of eggs per individual female. The high frequency of external abnormalities observed on brown bullhead from the contaminated sites did not appear to have a detrimental influence on fecundity. These results suggest that fecundity of the brown bullhead was not adversely affected in ecosystems altered by the presence of contaminated sediments. Increased fecundity of the brown bullhead from impacted rivers may be the result of reduced competition for an abundant invertebrate food source and limited predation by other fish species whose numbers are largely depleted in these degraded systems.

  10. 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.

  11. 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.

  12. 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...

  13. 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; Skarphéðinsdóttir, 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.

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

    PubMed

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

    2011-12-01

    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 (32)P-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. (32)P-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.

  15. 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.

  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. 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.

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

    PubMed

    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.

  19. 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.

  20. 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.

  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 sampled five locations: the Fox and Menominee rivers, Lake Michigan; Munuscong Lake, St. Mary's 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. Species-specific markers provide molecular genetic evidence for natural introgression of bullhead catfishes in Hungary

    PubMed Central

    Béres, Beatrix; Kánainé Sipos, Dóra; Müller, Tamás; Staszny, Ádám; Farkas, Milán; Bakos, Katalin; Urbányi, Béla

    2017-01-01

    Since three bullhead catfish species were introduced to Europe in the late 19th century, they have spread to most European countries. In Hungary, the brown bullhead (Ameiurus nebulosus) was more widespread in the 1970s–1980s, but the black bullhead (Ameiurus melas) has gradually supplanted since their second introduction in 1980. The introgressive hybridization of the two species has been presumed based on morphological examinations, but it has not previously been supported by genetic evidence. In this study, 11 different Hungarian habitats were screened with a new species-specific nuclear genetic, duplex PCR based, marker system to distinguish the introduced catfish species, Ameiurus nebulosus, Ameiurus melas, and Ameiurus natalis, as well as the hybrids of the first two. More than 460 specimens were analyzed using the above markers and additional mitochondrial sequence analyses were also conducted on >25% of the individuals from each habitat sampled. The results showed that only 7.9% of the specimens from two habitats belonged to Ameiurus nebulosus, and 92.1% were classified as Ameiurus melas of all habitats, whereas the presence of Ameiurus natalis was not detected. Two specimens (>0.4%) showed the presence of both nuclear genomes and they were identified as hybrids of Ameiurus melas and Ameiurus nebulosus. An additional two individuals showed contradicting results from the nuclear and mitochondrial assays as a sign of a possible footprint of introgressive hybridization that might have happened two or more generations before. Surprisingly, the level of hybridization was much smaller than expected based on the analyses of the North American continent’s indigenous stock from the hybrid zones. This phenomenon has been observed in several invasive fish species and it is regarded as an added level of complexity in the management of their rapid adaptation. PMID:28265489

  4. 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.

  5. 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 ...

  6. 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 280 mm 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 (17 km 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.

  7. 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.

  8. 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.

  9. Tumor prevalence and biomarkers of exposure and response in brown bullhead (Ameiurus nebulosus) from the Anacostia River, Washington, DC and Tuckahoe River, Maryland, USA.

    PubMed

    Pinkney, Alfred E; Harshbarger, John C; May, Eric B; Reichert, William L

    2004-03-01

    We evaluated liver and skin tumor prevalence and biomarkers of exposure and response in brown bullhead (Ameiurus nebulosus) from three locations in the Anacostia River (Washington, DC, USA), a Chesapeake Bay region of concern. The Tuckahoe River (Maryland, USA) served as a reference. Each river was sampled in fall 2000 and spring 2001. In the Anacostia, prevalence of liver tumors was 50 to 68%, and prevalence of skin tumors was 13 to 23% in large (> or = 260 mm, age > or = 3 years) bullheads. Liver and skin tumor prevalence was 10 to 17% and 0%, respectively, in small (150-225 mm, age 1-2 years) bullheads. Tuckahoe bullhead liver tumor prevalence was 0 to 3% (large) and 0% (small); none had skin tumors. Biliary polynuclear aromatic hydrocarbon (PAH)-like fluorescent metabolites and liver DNA adduct concentrations were elevated in large and small Anacostia bullheads. Mean adduct concentrations were 16 to 28 times higher than those in Tuckahoe fish. Chromatograms revealed a diagonal radioactive zone, indicating polycyclic aromatic compound (PAC)-DNA adducts. The biomarker data and the 10 to 17% liver tumor prevalence at ages 1 to 2 suggest that these year classes are likely to have a high prevalence as they reach age 3 and older. This study provides the strongest evidence to date of the role of PAHs in tumor development in Anacostia bullheads.

  10. Greening America's Capitals - Phoenix, AZ

    EPA Pesticide Factsheets

    This report shows design concepts to make pedestrians and bicyclists safer while maintaining on-street parking and providing space for a future streetcar or trolley in Phoenix, AZ. It also shows green infrastructure strategies for arid places.

  11. 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.

  12. 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…

  13. 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.

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

    PubMed

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

    2001-06-01

    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 (> or = 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 prevalence in Anacostia bullheads warrants concern and was similar to those at 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. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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...

  20. 76 FR 23787 - Voluntary Termination of Foreign-Trade Subzone 75D, STMicroelectronics, Inc., Phoenix, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-28

    ...., 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 of Foreign-Trade Subzone 75D at the STMicroelectronics, Inc., facility in Phoenix, Arizona (Board Order...

  1. 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...; Whereas, the City of Phoenix, grantee of Foreign-Trade Zone 75, submitted an application to the Board (FTZ... Maricopa County and portions of Pinal and Yavapai Counties, Arizona, within and adjacent to the...

  2. 78 FR 66267 - Safety Zone; HITS Triathlon Series; Colorado River; Lake Havasu, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-05

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; HITS Triathlon Series; Colorado River; Lake... establishing a safety zone upon the navigable waters of the Colorado River in support of the HITS Triathlon... Series; Colorado River, Lake Havasu City, AZ. (a) Location. The safety zone includes the waters in...

  3. 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.

  4. Whole genome sequencing and phylogenetic characterization of brown bullhead (Ameiurus nebulosus) origin ranavirus strains from independent disease outbreaks.

    PubMed

    Fehér, Enikő; Doszpoly, Andor; Horváth, Balázs; Marton, Szilvia; Forró, Barbara; Farkas, Szilvia L; Bányai, Krisztián; Juhász, Tamás

    2016-11-01

    Ranaviruses are emerging pathogens associated with high mortality diseases in fish, amphibians and reptiles. Here we describe the whole genome sequence of two ranavirus isolates from brown bullhead (Ameiurus nebulosus) specimens collected in 2012 at two different locations in Hungary during independent mass mortality events. The two Hungarian isolates were highly similar to each other at the genome sequence level (99.9% nucleotide identity) and to a European sheatfish (Silurus glanis) origin ranavirus (ESV, 99.7%-99.9% nucleotide identity). The coding potential of the genomes of both Hungarian isolates, with 136 putative proteins, were shared with that of the ESV. The core genes commonly used in phylogenetic analysis of ranaviruses were not useful to differentiate the two brown bullhead ESV strains. However genome-wide distribution of point mutations and structural variations observed mainly in the non-coding regions of the genome suggested that the ranavirus disease outbreaks in Hungary were caused by different virus strains. At this moment, due to limited whole genome sequence data of ESV it is unclear whether these genomic changes are useful in molecular epidemiological monitoring of ranavirus disease outbreaks. Therefore, complete genome sequencing of further isolates will be needed to identify adequate genetic markers, if any, and demonstrate their utility in disease control and prevention.

  5. Effects of temperature on biological and biochemical indicators of the life-history strategy of bullhead Cottus gobio.

    PubMed

    Reyjol, Y; Léna, J-P; Hervant, F; Pont, D

    2009-10-01

    The biological and biochemical effects of temperature on life-history strategy of female bullhead Cottus gobio were investigated. Fish from two populations (Bez Basin, south-east France) experiencing contrasted thermal environments (i.e. more or less stable) were reared during 4 months at three distinct temperatures (7, 9 or 12 degrees C). Both somatic (soma fresh mass and muscle triglyceride content) and reproductive (gonad fresh mass, fecundity, mean diameter of eggs and gonad triglyceride content) indicators were examined. Mixed models indicated that an increasing temperature had significant negative effects on all life-history indicators except for soma fresh mass. Differences in life-history strategy with regard to muscle and gonad triglyceride contents, however, suggest that populations experiencing more variable thermal environments may be better adapted than others to cope with an increasing temperature. These findings may have important implications for C. gobio populations, within the context of climate warming.

  6. 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.

  7. 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.

  8. 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.

  9. 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

    ... MARINE PARADES SAFETY OF LIFE ON NAVIGABLE WATERS § 100.1102 Marine Events on the Colorado River, between... weekend events between March and October Where: that portion of the Colorado River starting from the... of Commerce Date: Weekend in May or June Where: that portion of the Colorado River at...

  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 γ-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. A comparison of β-adrenoceptors and muscarinic cholinergic receptors in tissues of brown bullhead catfish (Ameiurus nebulosus) from the black river and old woman creek, Ohio

    USGS Publications Warehouse

    Steevens, Jeffery A.; Baumann, Paul C.; Jones, Susan B.

    1996-01-01

    β-Adrenoceptors (βARs) 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 βARs were found in the gill from Black River fish, possibly indicating a compensatory response subsequent to chemical stress.

  12. 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.

  13. Glutathione S-transferase expression in pollution-associated hepatic lesions of brown bullheads (Ameiurus nebulosus) from the Cuyahoga River, Cleveland, Ohio.

    PubMed

    Henson, K L; Gallagher, E P

    2004-07-01

    In rodents, overexpression of glutathione S-transferase pi is a characteristic feature of foci of cellular alteration (FCA) and neoplastic liver lesions induced by genotoxic chemicals. Alterations of glutathione S-transferase (GST) expression in hepatic lesions have also been reported in fish exposed to environmental carcinogens, and cellular GST expression may be an important determinant of growth and progression of chemical-associated liver tumors in certain fish species. In the present study, GST expression was examined in hepatic lesions of brown bullheads (n = 44) from the Cuyahoga River, a highly industrialized site located in Cleveland, Ohio. GST proteins were detected by immunohistochemistry and polyclonal antibodies that recognize either two major bullhead GST proteins or a pi-like GST isoform. Hepatic lesions were present in 70% of the fish and included biliary hyperplasia and biliary fibrosis; eosinophilic, basophilic, clear cell, and vacuolated FCA; and biliary neoplasms. Eosinophilic FCA and biliary tumors were the most prevalent preneoplastic and neoplastic lesions. GST expression in hyperplastic biliary tissue, FCA and tumors did not markedly differ from that of surrounding normal hepatocytes or biliary epithelium. Some hepatocytes within eosinophilic FCA had decreased GST expression. A complete absence of GST immunoreactive protein was not observed in any lesion, and there were no marked differences when comparing GST pi to overall GST expression. Our results indicate that GST expression in hepatic lesions of brown bullhead exposed to environmental carcinogens does not significantly differ from that in surrounding normal cells and is therefore not a useful predictor of environmental carcinogenesis in this species. Furthermore, the regulation and expression of GST pi in bullhead hepatocarcinogenesis appears to differ markedly from that during hepatocarcinogenesis in rats and some other fish species.

  14. Perfil de Franklin Chang- Díaz de Franklin Chang-Díaz

    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.

  15. An investigation of carbonic anhydrase activity in the gills and blood plasma of brown bullhead (Ameiurus nebulosus), longnose skate (Raja rhina), and spotted raffish (Hydrolagus colliei).

    PubMed

    Gilmour, Kathleen M; Shah, Bina; Szebedinszky, Cheryl

    2002-01-01

    Separated plasma and whole blood non-bicarbonate buffering capacities, together with plasma and gill carbonic anhydrase activities and endogenous plasma carbonic anhydrase inhibitor activity were investigated in three species of fish: the brown bullhead (Ameirus nebulosus), a teleost; the longnose skate (Raja rhina), an elasmobranch; and the spotted ratfish (Hydrolagus colliei), a chimaeran. The objective was to test the hypothesis that species possessing gill membrane-bound carbonic anhydrase and/or plasma carbonic anhydrase activity would also exhibit high plasma nonbicarbonate buffering capacity relative to whole blood non-bicarbonate buffering capacity and would lack an endogenous plasma carbonic anhydrase inhibitor. Separated plasma non-bicarbonate buffering capacity constituted > or = 40% of whole-blood buffering in all three species. In addition, all species lacked an endogenous plasma carbonic anhydrase inhibitor. Separated plasma from skate and ratfish contained carbonic anhydrase activity, whereas bullhead plasma did not. Examination of the subcellular distribution and characteristics of branchial carbonic anhydrase activity revealed that the majority of branchial carbonic anhydrase activity originated from the cytoplasmic fraction in all species, with only 3-5% being associated with a microsomal fraction. The microsomal carbonic anhydrase activity of bullhead and ratfish was significantly reduced by washing, indicating the presence of carbonic anhydrase activity that was not integrally associated with the membrane pellet, microsomal carbonic anhydrase activity in skate was unaffected by washing. In addition, microsomal carbonic anhydrase activity from skate and ratfish but not bullhead gills was released to a significant extent from its membrane association by treatment with phosphatidylinositol-specific phospholipase C. The results obtained for skate are consistent with published data for dogfish, suggesting that the possession of branchial membrane

  16. 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

  17. Development of Rolling Schedules for AZ31 Magnesium Alloy Sheets

    DTIC Science & Technology

    2015-06-01

    received AZ31B, a magnesium (Mg) alloy that contains approximately 3% aluminum and 1% zinc. In particular, we investigated the ability to roll AZ31B to...ARL-TR-7277 ● JUNE 2015 US Army Research Laboratory Development of Rolling Schedules for AZ31 Magnesium Alloy Sheets by...7277 ● JUNE 2015 US Army Research Laboratory Development of Rolling Schedules for AZ31 Magnesium Alloy Sheets by Laszlo Kecskes, Heidi

  18. 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.

  19. 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…

  20. 76 FR 45644 - Arizona Disaster #AZ-00016

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-29

    ... is hereby amended to modify the incident description for this disaster from Monument Fire to Monument... ADMINISTRATION Arizona Disaster AZ-00016 AGENCY: U.S. Small Business Administration. ACTION: Amendment 1. SUMMARY: This is an amendment of the Administrative declaration of disaster for the State of Arizona dated...

  1. 76 FR 42156 - Arizona Disaster #AZ-00016

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-18

    ... ADMINISTRATION Arizona Disaster AZ-00016 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Arizona dated 07/11/2011. Incident: Monument Fire. Incident Period: 06/12/2011 and continuing. Effective Date:...

  2. 78 FR 57923 - Arizona Disaster #AZ-00029

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-20

    ... ADMINISTRATION Arizona Disaster AZ-00029 AGENCY: Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of Arizona dated 09/13/2013. Incident: Yarnell Hill Fire. Incident Period: 06/28/2013 through 07/10/2013. Effective Date:...

  3. 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.

  4. Tumors in brown bullheads in the Chesapeake Bay watershed: analysis of survey data from 1992 through 2006.

    PubMed

    Pikney, Alfred E; Harshbarger, John C; Rutter, Michael A

    2009-06-01

    Liver and skin tumor prevalences in brown bullheads Ameiurus nebulosus have been used in the North American Great Lakes to designate highly contaminated areas of concern and monitor their recovery. Here we interpret the results of six surveys conducted in the Chesapeake Bay watershed between 1992 and 2006, with data for 647 fish. The objective has been to develop an adequate database to critically evaluate the use of tumor prevalence as a habitat quality indicator within the watershed. Surveys featured randomized fish collection; recording of sex, length, weight, and age; and histopathology of all livers and all raised skin lesions. The Bayes information criterion was used to analyze all possible combinations of age, gender, length, and weight as covariates for logistic regression. Length and gender were the covariates that best described liver tumor prevalence. There were no covariates in the model for skin tumor prevalence. In some surveys, biomarkers, such as biliary polynuclear aromatic hydrocarbon (PAH)-like metabolites, hepatic cytochrome P450 activity, and hepatic DNA adducts, were used with sediment and tissue chemistry data to evaluate classes of chemicals as likely contributors to tumor prevalence. We highlight two surveys of the Anacostia River, Washington, D.C. (average = 55% liver tumors, 23% skin tumors), where sediment PAHs, biliary PAH-like metabolites, and hepatic DNA adducts were high, suggesting that PAHs play a major role. We show that logistic regression is an appropriate procedure for comparing "contaminated" versus "reference" locations, and we evaluate the utility of tumor surveys as an environmental indicator for the Chesapeake Bay watershed.

  5. 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

    ... 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. This... of Lights will involve fifty vessels in Lake Havasu, AZ transiting Thompson Bay, proceeding...

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 76 FR 18378 - Amendment of Class E Airspace; Taylor, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-04

    ... Federal Aviation Administration 14 CFR Part 71 Amendment of Class E Airspace; Taylor, AZ AGENCY: Federal... Taylor Airport, Taylor, AZ, to accommodate aircraft using the CAMBO One Departure, and the Area Navigation (RNAV) standard instrument approach procedures at Taylor Airport. This will improve the safety...

  12. Histopathology of brown bullhead (Ameiurus nebulosus), smallmouth bass (Micropterus dolomieu), and yellow perch (Perca flavescens) in relation to polychlorinated biphenyl (PCB) contamination in the Hudson River.

    PubMed

    Pinkney, Alfred E; Myers, Mark S; Rutter, Michael A

    2017-01-01

    From the 1940s through 1977, at least 590,000kg of polychlorinated biphenyls (PCBs) were released into the Hudson River from General Electric manufacturing plants located in Hudson Falls and Fort Edward, New York. In 1984, the U.S. Environmental Protection Agency designated a nearly 322km reach as the Hudson River PCBs Superfund Site. Here we describe a Fish Health Assessment study, part of a Natural Resource Damage Assessment, that evaluated the prevalence of toxicopathic lesions in adult brown bullhead (Ameiurus nebulosus), smallmouth bass (Micropterus dolomieu), and yellow perch (Perca flavescens). In fall 2001, 29-51 fish of each species were collected in fall 2001 from highly contaminated areas below the plants (Thompson Island Pool (TIP) and Stillwater Dam Pool (STW)), an upriver reference area (Feeder Dam Pool (FDP)), and a reference lake, Oneida Lake (ODA). The focus was on histopathologic lesions and observations associated with contaminant exposure: liver-neoplasms, foci of cellular alteration, bile duct hyperplasia; testes-ovotestis (testicular oocytes), germ cell degeneration, altered developmental stage; ovaries-atresia and altered developmental stage. Lesions associated with PCB exposure were defined as those with significantly greater prevalence and/or severity in TIP and STW compared with ODA and FDP. For brown bullhead and smallmouth bass, no lesions or changes in gonadal development met those criteria. In yellow perch, ovarian atresia was the only lesion associated with PCB exposure. Prevalence was 53% in FDP, 75% in ODA, and 100% in both STW and TIP; severity increased from mostly minimal to mild-moderate. Because of the high prevalence of atresia in reference collections, it is likely that factors other than PCBs are also involved. As part of a post-dredging monitoring plan, we recommend assessing gonad structure and function in yellow perch collected at the time of spawning in locations with a range of PCB contamination.

  13. Antizyme (AZ) regulates intestinal cell growth independently of polyamines

    PubMed Central

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

    2014-01-01

    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 5mM difluoromethylornithine (DFMO) to inhibit ODC, DFMO + 5μM spermidine (SPD), DFMO+ 5μM spermine (SPM), or DFMO+ 10 μM 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

  14. 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

  15. 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...

  16. RadNet Air Data From Phoenix, AZ

    EPA Pesticide Factsheets

    This page presents radiation air monitoring and air filter analysis data for Phoenix, AZ from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  17. RadNet Air Data From Tucson, AZ

    EPA Pesticide Factsheets

    This page presents radiation air monitoring and air filter analysis data for Tucson, AZ from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  18. RadNet Air Data From Yuma, AZ

    EPA Pesticide Factsheets

    This page presents radiation air monitoring and air filter analysis data for Yuma, AZ from EPA's RadNet system. RadNet is a nationwide network of monitoring stations that measure radiation in air, drinking water and precipitation.

  19. Semi empirical hardness predictive model for AZ91 nanocomposite

    NASA Astrophysics Data System (ADS)

    Zaidi, N. H. A.; Jamaludin, S. B.; Zaidi, A. M. A.; Ahmad, K. R.

    2016-07-01

    AZ91 nanocomposite was exposed to several heat treatment processes and the effect of precipitation hardening on hardness was studied as a function of time and temperature. The investigation shows the significant of time and temperature are the main role in the precipitation hardening process of the nanocomposite. Kinetics study show a deceptive activation energy of 21 kJ/mol of the AZ91 nanocomposite. A relationship was derived to predict the maximum hardness at given time and temperature.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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...

  6. 75 FR 76293 - Radio Broadcasting Services; Peach Springs, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-08

    ... COMMISSION 47 CFR Part 73 Radio Broadcasting Services; Peach Springs, AZ AGENCY: Federal Communications... CFR Part 73 Radio, Radio broadcasting. 0 As stated in the preamble, the Federal Communications Commission amends 47 CFR part 73 as follows: PART 73--RADIO BROADCAST SERVICES 0 1. The authority...

  7. 77 FR 10649 - Modification of Class E Airspace; Douglas, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-23

    ... controlled airspace is necessary to accommodate aircraft using VHF Omni-Directional Radio Range/Distance... International Airport, Douglas, AZ. Decommissioning of the Cochise VHF Omni-Directional Radio Range Tactical Air Navigational Aid (VORTAC) has made this action necessary for the safety and management of aircraft...

  8. 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...

  9. 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.

  10. 75 FR 57383 - Modification of Class E Airspace; Willcox, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-21

    ... Class E airspace at Willcox, AZ, to accommodate aircraft using a new Area Navigation (RNAV) Global Positioning System (GPS) Standard Instrument Approach Procedures (SIAPs) at Cochise County Airport. This will... County Airport, to accommodate IFR aircraft executing new RNAV (GPS) SIAPs at the airport. This action...

  11. 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…

  12. 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.

  13. 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.

  14. Characterization of mussel H2A.Z.2: a new H2A.Z variant preferentially expressed in germinal tissues from Mytilus.

    PubMed

    Rivera-Casas, Ciro; González-Romero, Rodrigo; Vizoso-Vazquez, Ángel; Cheema, Manjinder S; Cerdán, M Esperanza; Méndez, Josefina; Ausió, Juan; Eirin-Lopez, Jose M

    2016-10-01

    Histones are the fundamental constituents of the eukaryotic chromatin, facilitating the physical organization of DNA in chromosomes and participating in the regulation of its metabolism. The H2A family displays the largest number of variants among core histones, including the renowned H2A.X, macroH2A, H2A.B (Bbd), and H2A.Z. This latter variant is especially interesting because of its regulatory role and its differentiation into 2 functionally divergent variants (H2A.Z.1 and H2A.Z.2), further specializing the structure and function of vertebrate chromatin. In the present work we describe, for the first time, the presence of a second H2A.Z variant (H2A.Z.2) in the genome of a non-vertebrate animal, the mussel Mytilus. The molecular and evolutionary characterization of mussel H2A.Z.1 and H2A.Z.2 histones is consistent with their functional specialization, supported on sequence divergence at promoter and coding regions as well as on varying gene expression patterns. More precisely, the expression of H2A.Z.2 transcripts in gonadal tissue and its potential upregulation in response to genotoxic stress might be mirroring the specialization of this variant in DNA repair. Overall, the findings presented in this work complement recent reports describing the widespread presence of other histone variants across eukaryotes, supporting an ancestral origin and conserved role for histone variants in chromatin.

  15. Constitutive turnover of histone H2A.Z at yeast promoters requires the preinitiation complex

    PubMed Central

    Tramantano, Michael; Sun, Lu; Au, Christy; Labuz, Daniel; Liu, Zhimin; Chou, Mindy; Shen, Chen; Luk, Ed

    2016-01-01

    The assembly of the preinitiation complex (PIC) occurs upstream of the +1 nucleosome which, in yeast, obstructs the transcription start site and is frequently assembled with the histone variant H2A.Z. To understand the contribution of the transcription machinery in the disassembly of the +1 H2A.Z nucleosome, conditional mutants were used to block PIC assembly. A quantitative ChIP-seq approach, which allows detection of global occupancy change, was employed to measure H2A.Z occupancy. Blocking PIC assembly resulted in promoter-specific H2A.Z accumulation, indicating that the PIC is required to evict H2A.Z. By contrast, H2A.Z eviction was unaffected upon depletion of INO80, a remodeler previously reported to displace nucleosomal H2A.Z. Robust PIC-dependent H2A.Z eviction was observed at active and infrequently transcribed genes, indicating that constitutive H2A.Z turnover is a general phenomenon. Finally, sites with strong H2A.Z turnover precisely mark transcript starts, providing a new metric for identifying cryptic and alternative sites of initiation. DOI: http://dx.doi.org/10.7554/eLife.14243.001 PMID:27438412

  16. 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.

  17. Suppression of discontinuous precipitation in AZ91 by addition of Sn

    NASA Astrophysics Data System (ADS)

    Jung, I. C.; Kim, Y. K.; Cho, T. H.; Oh, S. H.; Kim, T. E.; Shon, S. W.; Kim, W. T.; Kim, D. H.

    2014-01-01

    The effect of Sn (5 wt%) addition on the aging behavior of the AZ91 alloy has been investigated in the present study. The addition of Sn effectively suppresses the discontinuous precipitation during aging treatment. The aging response of the Sn containing AZ91 alloy is far better than that of the AZ91 alloy due to much higher density of continuous precipitation in the matrix. The yield strength and total elongation to failure at the peak aged condition of the AZ91 and Sn containing AZ91 alloys are 119.4 and 161.9 MPa and 8.8 and 8.6%, respectively, indicating that 35.6% increase of yield strength can be obtained by the addition of Sn in the AZ91 alloy maintaining almost same level of ductility.

  18. 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

  19. 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.

  20. Corrosion Susceptibilities of Magnesium Alloys AZ91, EZ33 and ZE41

    DTIC Science & Technology

    1983-06-01

    34lw/i TECHNICAL REPORT ARSCD-TR-83007 CORROSION SUSCEPTIBILITIES OF MAGNESIUFif ALLOYS AZ91 , EZ33 AND ZE41 ANTHONY GALLACCIO WILLIAM T. EBIHARA pI... AZ91 , EZ33 and ZE41 alloys Corrosion 20. ABsTrR ACT (Cotfmue a- reverisnel & /t nr-mw.e.• a idertifr by block number) An assessment was made of the...Discussion 3 Results AZ91 Panels 4 EZ33 Panels 4 ZE41 -Panels AZ91 :Housing 4 Discussion of Results 5 Conclusions 6 References 7 Distribution List 25

  1. 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.

  2. 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.

  3. Mexico City

    Atmospheric Science Data Center

    2013-04-18

    ... Two small brighter patches within the hazy area indicate low fog. In the left-hand panel, the city basin appears significantly clearer, but ... very high altitudes, in contrast to the low-lying haze and fog near Mexico City. When the stereo retrieval determines that a location is ...

  4. 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…

  5. City Play.

    ERIC Educational Resources Information Center

    Dargan, Amanda; Zeitlin, Steve

    2000-01-01

    Today, fewer city blocks preserve the confidence of lifestyle and urban geography that sustain traditional games and outdoor play. Large groups of children choosing sides and organizing Red Rover games are no longer commonplace. Teachers must encourage free play; urban planners must build cities that are safe play havens. (MLH)

  6. 78 FR 17869 - Safety Zone; Desert Storm Shootout; Lake Havasu, Lake Havasu City, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-25

    ... establishing a temporary safety zone on the navigable waters of the Colorado River in Lake Havasu, Lake Havasu... LLC is sponsoring the Desert Storm Shootout, which is to be held on the Colorado River in Lake Havasu... vessels intending to transit or anchor in a portion of the Colorado River from 8 a.m. to 6 p.m. on...

  7. Histone H2A.Z and DNA methylation are mutually antagonistic chromatin marks

    PubMed Central

    Zilberman, Daniel; Coleman-Derr, Devin; Ballinger, Tracy; Henikoff, Steven

    2010-01-01

    Eukaryotic chromatin is separated into functional domains differentiated by posttranslational histone modifications, histone variants, and DNA methylation1–6. Methylation is associated with repression of transcriptional initiation in plants and animals, and is frequently found in transposable elements. Proper methylation patterns are critical for eukaryotic development4,5, and aberrant methylation-induced silencing of tumor suppressor genes is a common feature of human cancer7. In contrast to methylation, the histone variant H2A.Z is preferentially deposited by the Swr1 ATPase complex near 5′ ends of genes where it promotes transcriptional competence8–20. How DNA methylation and H2A.Z influence transcription remains largely unknown. Here we show that in the plant Arabidopsis thaliana, regions of DNA methylation are quantitatively deficient in H2A.Z. Exclusion of H2A.Z is seen at sites of DNA methylation in the bodies of actively transcribed genes and in methylated transposons. Mutation of the MET1 DNA methyltransferase, which causes both losses and gains of DNA methylation4,5, engenders opposite changes in H2A.Z deposition, while mutation of the PIE1 subunit of the Swr1 complex that deposits H2A.Z17 leads to genome-wide hypermethylation. Our findings indicate that DNA methylation can influence chromatin structure and effect gene silencing by excluding H2A.Z, and that H2A.Z protects genes from DNA methylation. PMID:18815594

  8. 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...

  9. Twinning and Softening of Cast Magnesium Alloy AZ91 under Hot Compression

    NASA Astrophysics Data System (ADS)

    Junwei, Liu; Shiqiang, Lu; Xianjuan, Dong; Xuan, Xiao; Guifa, Li

    2013-11-01

    Cast magnesium alloy AZ91 is studied after uniaxial compression in the range from room temperature to 400°C. The alloy is tested for compression and its microstructure is determined. The values of the parameter of strain hardening are found. The main mechanisms of structural transformations developing under compressive deformation of alloy AZ91 at low and moderate temperatures are considered.

  10. 76 FR 2000 - Modification of Class E Airspace; Show Low, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-12

    ... Federal Aviation Administration 14 CFR Part 71 Modification of Class E Airspace; Show Low, AZ AGENCY... airspace at Show Low, AZ, to accommodate aircraft using a new Area Navigation (RNAV) Global Positioning System (GPS) Standard Instrument Approach Procedures at Show Low Regional Airport. This will improve...

  11. 76 FR 64041 - Proposed Amendment of Class E Airspace; Show Low, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-17

    ... Federal Aviation Administration 14 CFR Part 71 Proposed Amendment of Class E Airspace; Show Low, AZ AGENCY... action proposes to modify Class E airspace at Show Low Regional Airport, Show Low, AZ. Controlled...) standard instrument approach procedures at Show Low Regional Airport. The FAA is proposing this action...

  12. 76 FR 82113 - Amendment of Class E Airspace; Show Low, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-30

    ... Federal Aviation Administration 14 CFR Part 71 Amendment of Class E Airspace; Show Low, AZ AGENCY: Federal... Show Low Regional Airport, Show Low, AZ. Controlled airspace is necessary to accommodate aircraft using... Low Regional Airport. This improves the safety and management of Instrument Flight Rules...

  13. 78 FR 25404 - Proposed Establishment of Class E Airspace; Grand Canyon, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-01

    ... Range/Distance Measuring Equipment (VOR/DME) navigation aid, Grand Canyon, AZ, to facilitate vectoring... route domestic airspace extending upward from 1,200 feet above the surface at the Grand Canyon VOR/DME... airspace at the Grand Canyon VOR/DME, Grand Canyon, AZ. This proposal will be subject to an...

  14. 77 FR 2241 - Radio Broadcasting Services; Ehrenberg, First Mesa, Kachina Village, Wickenburg, and Williams, AZ...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-17

    ..., and Williams, AZ; and Application of Univision Radio License Corporation, KHOV-FM, Wickenburg, AZ... by Rocket Radio, Inc., proposes the allotment of FM Channel 287C2 at Williams, Arizona, as the... and hybrid application, filed by Univision Radio License Corporation, licensee of Station...

  15. 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

    ... Bureau of Land Management [LLAZC03000.L51050000.EA0000 LVRCA13SA040.241A, AZ-SRP-030-10-04 and AZ-SRP-030... Management, Interior. ACTION: Notice. SUMMARY: The Bureau of Land Management (BLM) Lake Havasu Field Office... 250'' and ``BITD 425'' events. DATES: These closures will be in effect from 2 p.m., January 11,...

  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…

  17. 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.

  18. Microstructure and properties of strip cast AZ91 Mg alloy

    NASA Astrophysics Data System (ADS)

    Park, Sung S.; Park, Young S.; Kim, Nack J.

    2002-11-01

    A study has been conducted on the microstructure and mechanical properties of the strip cast AZ91 Mg alloy. The microstructure of the as-cast strip is characterized by a fine equiaxed dendritic structure. There is a variation of secondary dendrite arm spacing throughout the thickness of the strip, showing the smallest value at the wheel surface and the largest value at the center. The distribution of Mg17Al12 particles is also not uniform in the as-cast strip. The microstructure of the solution treated strip consists of fine Mg grains and Al-Mn particles in the matrix with no Mg17Al12 particles. T6 treatment of the strip results in the precipitation of Mg17Al12 particles, the volume fraction of which decreases from the wheel side to the center of the strip. The strip cast AZ91 Mg alloy has the best combination of tensile properties in the T4 condition. It is believed that the good tensile properties of the T4 treated strip are due to the presence of Al-Mn particles, which induce homogeneous deformation.

  19. In Vitro Studies on the Degradability, Bioactivity, and Cell Differentiation of PRP/AZ31B Mg Alloys Composite Scaffold

    PubMed Central

    Zou, Jian; Xu, Hongwei; Li, Xiaolin

    2017-01-01

    In recent years, more and more methods have been developed to improve the bioactivity of the biodegradable materials in bone tissue regeneration. In present study, we used rat mesenchymal stem cells (rMSCs) to evaluate the outcomes of Mg alloys (AZ31B, Magnesium, and Aluminum) and Platelet-rich plasma (PRP)/Mg alloys on rMSCs biocompatibility and osteogenic differentiation. Water absorption experiments indicated that both bare AZ31B and PRP/AZ31B were capable of absorbing large amounts of water. But the water absorption ratio for PRP/AZ31B was significantly higher than that for bare AZ31B. The degradability experiments implied that both samples degraded at same speed. rMSCs on the surface of AZ31B distributed more and better than those on the AZ31B scaffold. In ALP activity experiment, the activity of rMSCs on the PRP/AZ31B was markedly higher than that on the AZ31B scaffolds on the 7th day and 14th day. qRT-PCR also showed that OPN and OCN were expressed in both samples. OPN and OCN expression in PRP/AZ31B sample were higher than those in bare AZ31B samples. In summary, the in vitro study implied that AZ31B combined with PRP could remarkably improve cell seeding, attachment, proliferation, and differentiation. PMID:28337451

  20. Corrosion resistance of biodegradable polymeric layer-by-layer coatings on magnesium alloy AZ31

    NASA Astrophysics Data System (ADS)

    Cui, Lan-Yue; Zeng, Rong-Chang; Zhu, Xiao-Xiao; Pang, Ting-Ting; Li, Shuo-Qi; Zhang, Fen

    2016-06-01

    Biocompatible polyelectrolyte multilayers (PEMs) and polysiloxane hybrid coatings were prepared to improve the corrosion resistance of biodegradable Mg alloy AZ31. The PEMs, which contained alternating poly(sodium 4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH), were first self-assembled on the surface of the AZ31 alloy substrate via electrostatic interactions, designated as (PAH/PSS)5/AZ31. Then, the (PAH/PSS)5/AZ31 samples were dipped into a methyltrimethoxysilane (MTMS) solution to fabricate the PMTMS films, designated as PMTMS/(PAH/PSS)5/AZ31. The surface morphologies, microstructures and chemical compositions of the films were investigated by FE-SEM, FTIR, XRD and XPS. Potentiodynamic polarization, electrochemical impedance spectroscopy and hydrogen evolution measurements demonstrated that the PMTMS/(PAH/PSS)5/AZ31 composite film significantly enhanced the corrosion resistance of the AZ31 alloy in Hank's balanced salt solution (HBSS). The PAH and PSS films effectively improved the deposition of Ca-P compounds including Ca3(PO4)2 and hydroxyapatite (HA). Moreover, the corrosion mechanism of the composite coating was discussed. These coatings could be an alternative candidate coating for biodegradable Mg alloys.

  1. Magnesium alloy AZ91 exhibits antimicrobial properties in vitro but not in vivo.

    PubMed

    Brooks, Emily K; Ahn, Richard; Tobias, Menachem E; Hansen, Lisa A; Luke-Marshall, Nicole R; Wild, Linda; Campagnari, Anthony A; Ehrensberger, Mark T

    2017-01-27

    Magnesium alloys hold great promise for developing orthopedic implants that are biocompatible, biodegradable, and mechanically similar to bone tissue. This study evaluated the in vitro and in vivo antimicrobial properties of magnesium-9%aluminum-1%zinc (AZ91) and commercially pure titanium (cpTi) against Acinetobacter baumannii (Ab307). The in vitro results showed that as compared to cpTi, incubation with AZ91 significantly reduced both the planktonic (cpTi = 3.45e8, AZ91 = 8.97e7, p < 0.001) colony forming units (CFU) and biofilm-associated (cpTi = 3.89e8, AZ91 = 1.78e7, p = 0.01) CFU of Ab307. However, in vivo results showed no significant differences in the CFU enumerated from the cpTi and AZ91 implants following a 1-week implantation in an established rodent model of Ab307 implant associated infection (cpTi = 5.23e3, AZ91 = 2.46e3, p = 0.29). It is proposed that the in vitro results were associated with an increased pH in the bacterial culture as a result of the AZ91 corrosion process. The robust in vivo buffering capacity likely diminished this corrosion associated pH antimicrobial effect. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017.

  2. 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 α-Mg matrix and γ-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 γ-Mg17Al12 phase decrease, because of the newly formed Al-Nd phase. And the γ-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.

  3. 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.

  4. 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

  5. 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 200°C. The activation energy of grain boundary motion of the TRC material was calculated to be 167 kJ/mol.

  6. Influence of deformation on precipitation in AZ80 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Yang, Ping; Wang, Li-Na; Xie, Qing-Ge; Li, Ji-Zhong; Ding, Hua; Lu, Lin-Lin

    2011-06-01

    Precipitates in the conventionally processed (solution treatment followed by aging) AZ80 alloy are coarse, cellular, and incoherent. They nucleate and grow on the basal planes of the matrix or distribute discontinuously in the alloy. Their unique morphology and undesired distribution make them ineffective for precipitation strengthening. This condition, however, can be modified by applying selected deformation and heat treatment conditions. The effect of deformation and heat treatment on the morphology and distribution of precipitates has been studied. Deformation was introduced by hot extrusion, cold rolling, or equal channel angular pressing (ECAP). The microstructures were characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results showed that cold deformation improved precipitation more significantly than hot deformation, and twinning promoted precipitation more effectively than slip. When ECAP was applied, the Bc-route induced more precipitates than the A-route.

  7. 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.

  8. 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.

  9. 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.

  10. Unhappy Cities

    PubMed Central

    Glaeser, Edward L.; Gottlieb, Joshua D.; Ziv, Oren

    2016-01-01

    There are persistent differences in self-reported subjective well-being across US metropolitan areas, and residents of declining cities appear less happy than others. Yet some people continue to move to these areas, and newer residents appear to be as unhappy as longer-term residents. While historical data on happiness are limited, the available facts suggest that cities that are now declining were also unhappy in their more prosperous past. These facts support the view that individuals do not maximize happiness alone but include it in the utility function along with other arguments. People may trade off happiness against other competing objectives. PMID:27546979

  11. 75 FR 57327 - Environmental Impact Statement; Pinal County, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-20

    ..., Threatened and Endangered species, jurisdictional waters of the United States, air and noise quality... Nation, Salt River Project, Phoenix-Mesa Gateway Airport Authority, Town of Florence, City of...

  12. 75 FR 44725 - Proposed Establishment of Class E Airspace; Clifton/Morenci, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ..., AZ. To accommodate aircraft using a new Area Navigation (RNAV) Global Positioning System (GPS... action must submit with those comments a self-addressed stamped postcard on which the following...

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

    PubMed Central

    Jeronimo, Célia; Watanabe, Shinya; Kaplan, Craig D.; Peterson, Craig L.; Robert, François

    2015-01-01

    SUMMARY 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 RNA polymerase II (RNAPII) 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. Thus, chaperone-mediated H2A.Z confinement is crucial for restricting the chromatin signature of gene promoters, which otherwise may license or promote cryptic transcription. PMID:25959393

  14. 78 FR 34558 - Modification of Class E Airspace; Clifton/Morenci, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ..., 98057; telephone (425) 203-4537. SUPPLEMENTARY INFORMATION: History On March 26, 2013, the FAA published... airspace areas extending upward from 700 feet or more above the surface of the earth. * * * * * AWP AZ...

  15. 75 FR 49526 - Freescale Semiconductor, Inc., Technical Information Center, Tempe, AZ; Freescale Semiconductor...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-13

    ... Employment and Training Administration Freescale Semiconductor, Inc., Technical Information Center, Tempe, AZ; Freescale Semiconductor, Inc., Technical Information Center, Woburn, MA; Amended Certification Regarding... Semiconductor, Inc., Technical Information Center, Tempe, Arizona. The notice was published in the...

  16. 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

    ... Ground), Yuma, AZ. The establishment of an air traffic control tower has made this action necessary for... control tower has made this action necessary and provides the required controlled airspace for the...

  17. Remediation System Evaluation, A-Z Automotive in West Milford, New Jersey

    EPA Pesticide Factsheets

    The A-Z Automotive site is a former gasoline retail outlet and automobile service station located on Union Valley Road between St. George Street and Lou Ann Boulevard in West Milford, Passaic County, New Jersey.

  18. 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

    .... An informal docket may also be examined during normal business hours at the Northwest Mountain... extending upward from 700 feet or more above the surface of the earth. * * * * * AWP AZ E5 Laguna AAF,...

  19. 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

  20. System Description for Tank 241-AZ-101 Waste Retrieval Data Acquisition System

    SciTech Connect

    ROMERO, S.G.

    2000-02-14

    The proposed activity provides the description of the Data Acquisition System for Tank 241-AZ-101. This description is documented in HNF-5572, Tank 241-AZ-101 Waste Retrieval Data Acquisition System (DAS). This activity supports the planned mixer pump tests for Tank 241-AZ-101. Tank 241-AZ-101 has been selected for the first full-scale demonstration of a mixer pump system. The tank currently holds over 960,000 gallons of neutralized current acid waste, including approximately 12.7 inches of settling solids (sludge) at the bottom of the tank. As described in Addendum 4 of the FSAR (LMHC 2000a), two 300 HP mixer pumps with associated measurement and monitoring equipment have been installed in Tank 241-AZ-101. The purpose of the Tank 241-AZ-101 retrieval system Data Acquisition System (DAS) is to provide monitoring and data acquisition of key parameters in order to confirm the effectiveness of the mixer pumps utilized for suspending solids in the tank. The suspension of solids in Tank 241-AZ-101 is necessary for pretreatment of the neutralized current acid waste and eventual disposal as glass via the Hanford Waste Vitrification Plant. HNF-5572 provides a basic description of the Tank 241-AZ-101 retrieval system DAS, including the field instrumentation and application software. The DAS is provided to fulfill requirements for data collection and monitoring. This document is not an operations procedure or is it intended to describe the mixing operation. This USQ screening provides evaluation of HNF-5572 (Revision 1) including the changes as documented on ECN 654001. The changes include (1) add information on historical trending and data backup, (2) modify DAS I/O list in Appendix E to reflect actual conditions in the field, and (3) delete IP address in Appendix F per Lockheed Martin Services, Inc. request.

  1. Interaction of polyamines and mTOR signaling in the synthesis of antizyme (AZ)

    PubMed Central

    Ray, Ramesh M.; Bavaria, Mitul; Johnson, Leonard R.

    2015-01-01

    Tissue polyamine levels are largely determined by the activity of ornithine decarboxylase (ODC, EC 4.1.17), which catalyzes the conversion of ornithine to the diamine putrescine. The activity of the enzyme is primarily regulated by a negative feedback mechanism involving ODC antizyme (AZ). Our previous studies demonstrated that AZ synthesis is stimulated by the absence of amino acids, the levels of which are sensed by the mTOR complex containing TORC1, which is stimulated by amino acids and inhibited by their absence, and TORC2 the function of which is not well defined. Polyamines, which cause a +1 ribosomal frameshift during the translation of AZ mRNA are required to increase AZ synthesis in both the presence and absence of amino acids. Amino acid starvation increases TORC2 activity. We have demonstrated that mTORC2 activity is necessary for AZ synthesis in the absence of amino acids. Tuberous sclerosis protein (TSC), a negative regulator of mTOR function regulates the activities of both the TORC1 and TORC2. TSC2 knockdown increased mTORC1 activity with concomitant inhibition of mTORC2 activity eliminating AZ induction in the absence of amino acids as well as that induced by spermidine. Thus, these results clearly demonstrate that in addition to polyamines, mTORC2 activity is necessary for AZ synthesis. Moreover, our results support a role for mTORC2 in the synthesis of a specific protein, AZ, which regulates growth of intestinal epithelial cells. PMID:26093026

  2. 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.

  3. The Influence of Novel Alloying Additions on the Performance of Magnesium Alloy AZ31B

    DTIC Science & Technology

    2013-11-01

    2009. 2 key criterion, so that potential strength increase from grain size reduction and/or solid solution strengthening would occur. Moreover, it...the following elements were selected: indium (In), bismuth (Bi), strontium (Sr), Zr, titanium (Ti), calcium (Ca), lithium (Li), yttrium (Y...addition, a relatively simple Mg alloy (AZ31B) was chosen as the baseline material. AZ31B is a solid -solution-strengthened alloy with minimal

  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

  5. Transcriptional and post-transcriptional regulation of histone variant H2A.Z during sea urchin development.

    PubMed

    Hajdu, Mihai; Calle, Jasmine; Puno, Andrea; Haruna, Aminat; Arenas-Mena, César

    2016-12-01

    Histone variant H2A.Z promotes chromatin accessibility at transcriptional regulatory elements and is developmentally regulated in metazoans. We characterize the transcriptional and post-transcriptional regulation of H2A.Z in the purple sea urchin Strongylocentrotus purpuratus. H2A.Z depletion by antisense translation-blocking morpholino oligonucleotides during early development causes developmental collapse, in agreement with its previously demonstrated general role in transcriptional multipotency. During H2A.Z peak expression in 24-h embryos, endogenous H2A.Z 3' UTR sequences stabilize GFP mRNAs relative to those with SV40 3' UTR sequences, although the 3' UTR of H2A.Z does not determine the spatial distribution of H2A.Z transcripts during embryonic and postembryonic development. We elaborated an H2A.Z::GFP BAC reporter that reproduces embryonic H2A.Z expression. Genome-wide chromatin accessibility analysis using ATAC-seq revealed a cis-regulatory module (CRM) that, when deleted, causes a significant decline of the H2A.Z reporter expression. In addition, the mutation of a Sox transcription factor binding site motif and, more strongly, of a Myb motif cause significant decline of reporter gene expression. Our results suggest that an undetermined Myb-family transcription factor controls the transcriptional regulation of H2A.Z.

  6. The Cities.

    ERIC Educational Resources Information Center

    Nathan, Richard P.; Dommel, Paul R.

    Over the past two decades, direct payments from the Federal Government to local governments has increased more than sixfold as a percentage of the revenues local governments raise on their own. Both the Ford budget and the Carter budget revisions for 1977 and 1978 contain policy changes with important implications for cities. In this document…

  7. Effects of Te addition on microstructure and mechanical properties of AZ91 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Cui, Shujing; Wu, Xiangwei; Liu, Rongxue; Teng, Xinying; Leng, Jinfeng; Geng, Haoran

    2017-01-01

    To improve the mechanical properties of AZ91 alloy, the effects of Te addition on the as-cast microstructure and mechanical properties of AZ91 magnesium alloy were investigated by means of optical microscope (OM), scanning electronic microscope (SEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD) and tensile testing machine. The results show that the microstructure of Te-containing AZ91 alloys is refined with the improvement of mechanical properties of AZ91 alloys. When the addition of Te is 0.9 wt%, the grain becomes finer, with primary β-Mg17Al12 phases distributed, and new granule-like Al2Te3 phases emerge at the grain boundary with dispersive distribution. As a result, tensile strength and yield strength of as-cast AZ91 alloy are improved from 150 MPa and 80 MPa to 180 MPa and 107 MPa. The optimal tensile properties were obtained. This was attributed to the smaller grain size strengthening and new emerged hard Al2Te3 phase strengthening. The present findings provide a new way for strengthening of AZ91 alloys.

  8. 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 β(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.

  9. 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.

  10. Bioactive benzofuran derivatives: moracins A-Z in medicinal chemistry.

    PubMed

    Naik, Ravi; Harmalkar, Dipesh S; Xu, Xuezhen; Jang, Kyusic; Lee, Kyeong

    2015-01-27

    Benzofuran heterocycles are fundamental structural units in a variety of biologically active natural products as well as synthetic materials. Over the time, benzofuran derivatives have attracted many researchers due to the broad scope of their biological activity, which include anticancer, antimicrobial, immunomodulatory, antioxidant and anti-inflammatory properties. Egonol, homoegonol and moracin families are biologically active natural products containing benzofuran heterocycle as basic structural units. This paper focuses on the moracin family (moracin A to Z). Morus, a genus of flowering plants in the family Moraceae, comprises 10-16 species of deciduous trees commonly known as mulberries. The root bark, stem bark and leaves of Morus alba, M. lhou, Morus macroura are the main sources for arylbenzofuran derivatives including the moracins. A large volume of research has been carried out on moracins and their derivatives, which has shown the pharmacological importance of this benzofuran heterocyclic nucleus. In this mini-review, we attempt to highlight the importance of moracins, as they have been a major source for drug development. Herein, we also summarize the current state of the art concerning the synthesis and medicinal use of moracins A-Z.

  11. Characterization of AZ31 magnesium alloy by duplex process combining laser surface melting and plasma electrolytic oxidation

    NASA Astrophysics Data System (ADS)

    Liu, Cancan; Liang, Jun; Zhou, Jiansong; Li, Qingbiao; Wang, Lingqian

    2016-09-01

    Top ceramic coatings were fabricated on the laser surface melting (LSM) modified AZ31 alloy by plasma electrolytic oxidation (PEO) in a phosphate electrolyte. The effect of LSM treatment on the microstructure and corrosion behavior of the bare and PEO treated AZ31 alloy was evaluated. Results showed that LSM treatment produced a homogeneous modified layer with redistributed intermetallic compounds, resulting in enhanced corrosion resistance of AZ31 alloy. The LSM treatment had no obvious influence on the surface and cross-sectional microstructures of the PEO coatings on AZ31 alloy. Besides, MgO was the main constituent for PEO coatings, regardless of LSM pretreatment. However, the long-term corrosion properties of the PEO coated AZ31 alloy with LSM pretreatment revealed large enhancement. Based on the analysis of microstructure and corrosion property, the corrosion mechanisms of the PEO and LSM-PEO coated AZ31 alloy were proposed.

  12. 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.

  13. 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.

  14. 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... County Foreign Trade Zone, Inc., grantee of FTZ 277, requesting temporary/ interim manufacturing...

  15. 75 FR 19246 - Safety Zone; Desert Storm, Lake Havasu, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-14

    ... zone within the Thompson Bay region of the navigable waters of the Colorado River in Lake Havasu, Lake... to be held on Thompson Bay region of the Colorado River in Lake Havasu City, Arizona. A temporary... vessels intending to transit or anchor in a portion of the lower Colorado River from 8 a.m. on April...

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

    NASA Astrophysics Data System (ADS)

    Hörz, 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.

  17. 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

  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.

  19. 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…

  20. 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 435°C, 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 430~435°C. 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.

  1. 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.

  2. 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.

  3. 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...

  4. 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 β-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 β-Mg17Al12 phase and it was dissolved into α-Mg phase during heat treatment at 400 °C. The β-phase became center for hydrogen evolution during phosphating reaction (cathodic sites). The decreased volume fraction of the β-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)2·4H2O (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.

  5. 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), 150 mM 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 3 days 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 3 days, 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

  6. 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

  7. 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

  8. Differential deposition of H2A.Z in rice seedling tissue during the day-night cycle.

    PubMed

    Zhang, Kang; Xu, Wenying; Wang, Chunchao; Yi, Xin; Su, Zhen

    2017-03-04

    Chromatin structure has an important role in modulating gene expression. The incorporation of histone variants into the nucleosome leads to important changes in the chromatin structure. The histone variant H2A.Z is highly conserved between different species of fungi, animals, and plants. However, dynamic changes to H2A.Z in rice have not been reported during the day-night cycle. In this study, we generated genome wide maps of H2A.Z for day and night time in harvested seedling tissues by combining chromatin immunoprecipitation and high-throughput sequencing. The analysis results for the H2A.Z data sets detected 7099 genes with higher depositions of H2A.Z in seedling tissues harvested at night compared with seedling tissues harvested during the day, whereas 4597 genes had higher H2A.Z depositions in seedlings harvested during the day. The gene expression profiles data suggested that H2A.Z probably negatively regulated gene expression during the day-night cycle and was involved in many important biologic processes. In general, our results indicated that H2A.Z may play an important role in plant responses to the diurnal oscillation process.

  9. 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 93—Special Flight Rules in the Vicinity of the Grand Canyon National Park,...

  10. 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 93—Special Flight Rules in the Vicinity of the Grand Canyon National Park,...

  11. 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

    ... 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 93—Special Flight Rules in the Vicinity of the Grand Canyon National Park,...

  12. 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 93—Special Flight Rules in the Vicinity of the Grand Canyon National Park,...

  13. 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 93—Special Flight Rules in the Vicinity of the Grand Canyon National Park,...

  14. 77 FR 63873 - Johnson Controls, Inc. Including On-Site Leased Workers of Valley Staffing and AZ Quality Hudson...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-17

    ... certification to include workers leased from AZ Quality working on-site at the Hudson, Wisconsin location of... Employment and Training Administration Johnson Controls, Inc. Including On-Site Leased Workers of Valley Staffing and AZ Quality Hudson, Wisconsin; Amended Certification Regarding Eligibility To Apply for...

  15. Women in Cities.

    ERIC Educational Resources Information Center

    Hurst, Liz

    1982-01-01

    Suggesting that women are at a disadvantage in cities and towns, discusses experiences of women at home, working women, women traveling, shopping, and growing old in cities. Includes suggestions for studying women in cities. (JN)

  16. 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?

  17. 65 FR 56870 - AZ3, Inc., d/b/a/ BCBG Max Azria, Provisional Acceptance of a Settlement Agreement and Order

    Federal Register 2010, 2011, 2012, 2013, 2014

    2000-09-20

    ... COMMISSION AZ3, Inc., d/b/a/ BCBG Max Azria, Provisional Acceptance of a Settlement Agreement and Order...-accepted Settlement Agreement with AZ3, Inc., d/b/a BCBG Max Azria, containing a civil penalty of $75,000..., Secretary. Consumer Product Safety Commission In the Matter of AZ3, Inc., d/b/a BCBG Max Azria;...

  18. 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

  19. 76 FR 3570 - Proposed Amendment of Class E Airspace; Taylor, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-20

    ...This action proposes to modify Class E airspace at Taylor Airport, Taylor, AZ. Controlled airspace is necessary to accommodate aircraft using the CAMBO One Departure Area Navigation (RNAV) out of Taylor Airport. The FAA is proposing this action to enhance the safety and management of aircraft operations at Taylor Airport, Taylor,...

  20. Tank 241-AZ-102 SuperLig 639 Technetium Ion Exchange Eluate Evaporation Study

    SciTech Connect

    King, W.D.

    2001-02-15

    As part of the Hanford River Protection Project (RPP), the Savannah River Technology Center (SRTC) has conducted tests on the pretreatment and vitrification of a radioactive waste sample from Hanford Tank 241-AZ-102. The original, AZ-102 sample which was received at SRTC was characterized and filtered to remove entrained solids.1 The sample was then passed sequentially through ion exchange columns containing SuperLig{reg_sign} 644 and 639 resins for the removal of cesium and technetium ions (Tc removed as pertechnetate, TcO{sub 4}{sup {minus}}), respectively.2 The cesium and technetium absorbed to the resins was then eluted to give separate eluate solutions containing relatively high concentrations of Cs{sup +} and TcO{sub 4}{sup {minus}}. According to the current plant design, the decontaminated Tank 241-AZ-102 sample and the eluate solutions will be subjected to separate evaporation and vitrification processes to give low- and high-activity waste glasses, respectively. This report describes evaporation testing of the Tc eluate solution derived from ion exchange processing of the Tank 241-AZ-102 sample with SuperLig 639 resin.

  1. 75 FR 38754 - Safety Zone; IJSBA World Finals; Lower Colorado River, Lake Havasu, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-06

    .... USCG-2010-0509] RIN 1625-AA00 Safety Zone; IJSBA World Finals; Lower Colorado River, Lake Havasu, AZ... IJSBA World Finals. This temporary safety zone is necessary to provide for the safety of the... World Finals. The event will consist of 300 to 750 personal watercrafts racing in a circular course....

  2. 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...

  3. 76 FR 42155 - Arizona Disaster #AZ-00017 Declaration of Economic Injury

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-18

    ... ADMINISTRATION Arizona Disaster AZ-00017 Declaration of Economic Injury AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Economic Injury Disaster Loan (EIDL) declaration for the State of Arizona, dated 07/11/2011. Incident: Wallow Fire. Incident Period: 05/29/2011...

  4. 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.

  5. Effect of cryogenic thermocycling treatment on the structure and properties of magnesium alloy AZ91

    NASA Astrophysics Data System (ADS)

    Yong, Jiang; Ding, Chen; Qiong, Jiang

    2012-03-01

    The effect of cryogenic thermocycling treatment on the microstructure, mechanical and cryogenic properties of alloy Mg - 9% Al - 0.9% Zn (AZ91) is studied. Thermocycling in the cryogenic range causes a change in the content and distribution of particles of segregations, which is responsible for improvement of the mechanical properties and corrosion resistance of the alloy.

  6. Effect of Sb on the microstructure and mechanical properties of AZ91 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Wang, Qudong; Chen, Wenzhou; Ding, Wenjiang; Zhu, Yanping; Mabuchi, M.

    2001-03-01

    Effects of Sb addition on the microstructure, mechanical properties, and fracture behaviors of AZ91 magnesium alloy, as well as the sensitivity to section thickness of the structure and mechanical properties, have been studied. The results show that when Sb is added into the AZ91 alloy, the grain is refined, the Mg17Al12 phase is refined and granulated, and a new Mg3Sb2 phase is formed and becomes coarse needle-shaped as Sb content increases. The room-temperature tensile strength, elongation, and impact toughness increase first, and then decrease with increasing Sb content. The study on sensitivity to section thickness shows that, when composition is constant, the room-temperature tensile strength and elongation increase with the reduction of section thickness; when section thickness is constant, the room-temperature tensile strength and elongation increase first, and then decrease with increasing Sb content. Additionally, the Sb addition improves the tensile strength of the AZ91 alloy at 100°C and 150°C. The room-temperature tensile and impact fractographs of the AZ91 alloy show intergranular fracture. With increasing Sb content, the tearing deformation zones on the both fractographs enlarge at first, and then diminish, which is consistent with the change of tensile strength, elongation, and impact toughness increasing first, and then reducing with increasing Sb content.

  7. 78 FR 40381 - Establishment of Class E Airspace; Grand Canyon, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-05

    ... Canyon VHF Omni-Directional Radio Range/Distance Measuring Equipment (VOR/DME) navigation aid, Grand..., at the Grand Canyon VOR/DME navigation aid, Grand Canyon, AZ, to accommodate IFR aircraft under... within the scope of that authority as it establishes controlled airspace at the Grand Canyon...

  8. 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.

  9. 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.

  10. 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....

  11. 78 FR 23135 - Safety Zone; Blue Water Resort & Casino West Coast Nationals; Parker, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-18

    ... temporary safety zone includes the waters of the Colorado River between Headgate Dam and 0.5 miles north of... vessels intending to transit or anchor in the impacted portion of the Colorado River from 6 a.m. to 6 p.m... Nationals, Parker, AZ. (a) Location. This temporary safety zone includes the waters of the Colorado...

  12. 78 FR 63869 - Change of Using Agency for Restricted Areas R-2309 and R-2312, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-25

    ... Federal Aviation Administration 14 CFR Part 73 RIN 2120-AA66 Change of Using Agency for Restricted Areas R-2309 and R-2312, AZ AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final rule. SUMMARY: This action updates the name of the using agency for Restricted Areas R-2309 and R-2312 located...

  13. 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... 275 and 290 watt solar panels for industrial use. Components and materials sourced from abroad... to choose the duty rates during customs entry procedures that apply to solar panels (duty-free)...

  14. 78 FR 33703 - Safety Zone; Great Western Tube Float; Colorado River; Parker, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-05

    ... No. USCG-2013-0268] RIN 1625-AA00 Safety Zone; Great Western Tube Float; Colorado River; Parker, AZ... Tube Float on June 8, 2013. This temporary safety zone is necessary to provide for the safety of the....). The Parker Area Chamber of Commerce is sponsoring the Great Western Tube Float, which is held on...

  15. Dry Sliding Wear Behavior of Fly Ash Cenosphere/AZ91D Mg Alloy Composites

    NASA Astrophysics Data System (ADS)

    Yu, S. R.; Huang, Z. Q.

    2014-10-01

    Fly ash cenosphere/AZ91D Mg alloy (FAC/AZ91D) composites were prepared using stir casting method. The effects of the applied load, the wearing time, and the diameter and the content of fly ash cenosphere on the wear behavior of the composites were investigated under dry sliding condition. The results showed the wear resistance of FAC/AZ91D composites is generally better than that of AZ91D Mg alloy. The mass fraction and diameter of FAC have important effects on the wear resistance of the composites, and the wear resistance of the composites is excellent when the mass fraction and diameter of FAC are moderate. When the mass fraction and diameter of FAC are more than the critical values, the wear resistance of the composites lowers again. The wear resistance of the composites decreases with the increase in the applied load. The relationship between the worn mass loss and the applied load is nonlinear. When the applied load is smaller, the worn mass loss of the composites increases rapidly with the increase of the applied load. These research results show that the composites have broad application prospects under dry sliding wear condition, and they can provide guidance for the selection of the raw materials, the structure design, and the application conditions of the composites.

  16. 78 FR 78298 - Proposed Establishment of Class E Airspace; Phoenix, AZ

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-26

    ...This action proposes to establish Class E airspace at the Phoenix VHF Omni-Directional Radio Range Tactical Air Navigation Aid (VORTAC), Phoenix, AZ, to facilitate vectoring of Instrument Flight Rules (IFR) aircraft under control of Albuquerque Air Route Traffic Control Center (ARTCC). The FAA is proposing this action to enhance the safety and management of aircraft operations within the......

  17. 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,...

  18. 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.

  19. 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 β-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.

  20. Electrophoretic Deposition of 3YSZ Coating on AZ91D Alloy Using Al and Ni-P Interlayers

    NASA Astrophysics Data System (ADS)

    Shahriari, A.; Aghajani, H.

    2016-10-01

    Electrophoretic deposition was used in order to apply the zirconia stabilized by 3 mol% Y2O3 onto the surface of the magnesium alloy AZ91D. Two different interlayers which were including aluminum layer and Ni-P layer were prepared between the AZ91D surface and YSZ coating and the effect of them on the quality of YSZ coating was investigated. The surface morphologies of the coatings were studied by scanning electron microscopy, and their compositions were determined by x-ray diffraction. The corrosion resistance of the coatings was evaluated by electrochemical impedance spectroscopy in 3.5% NaCl neutral solution. Also, the stability of coating was investigated by the Rockwell C indentation test. The results showed that the YSZ coating applied onto different interlayers on AZ91D improves the corrosion resistance of this alloy due to increase in charge-transfer resistance of the AZ91D surface. Also, the aluminum interlayer has a favorable effect on the densification of the coating by formation of aluminum oxide. Furthermore, the corrosion resistance of AZ91D that coated by YSZ and aluminum layer was improved compared to that of coated AZ91D with YSZ and Ni-P layer. The presence of interlayers can make the stability of the YSZ coating improved on the surface of AZ91D.

  1. Oncogenic potential of histone-variant H2A.Z.1 and its regulatory role in cell cycle and epithelial-mesenchymal transition in liver cancer

    PubMed Central

    Eun, Jung Woo; Shen, Qingyu; Kim, Hyung Seok; Shin, Woo Chan; Ahn, Young Min; Park, Won Sang; Lee, Jung Young; Nam, Suk Woo

    2016-01-01

    H2A.Z is a highly conserved H2A variant, and two distinct H2A.Z isoforms, H2A.Z.1 and H2A.Z.2, have been identified as products of two non-allelic genes, H2AFZ and H2AFV. H2A.Z has been reported to be overexpressed in breast, prostate and bladder cancers, but most studies did not clearly distinguish between isoforms. One recent study reported a unique role for the H2A.Z isoform H2A.Z.2 as a driver of malignant melanoma. Here we first report that H2A.Z.1 plays a pivotal role in the liver tumorigenesis by selectively regulating key molecules in cell cycle and epithelial-mesenchymal transition (EMT). H2AFZ expression was significantly overexpressed in a large cohort of hepatocellular carcinoma (HCC) patients, and high expression of H2AFZ was significantly associated with their poor prognosis. H2A.Z.1 overexpression was demonstrated in a subset of human HCC and cell lines. H2A.Z.1 knockdown suppressed HCC cell growth by transcriptional deregulation of cell cycle proteins and caused apoptotic cell death of HCC cells. We also observed that H2A.Z.1 knockdown reduced the metastatic potential of HCC cells by selectively modulating epithelial-mesenchymal transition regulatory proteins such as E-cadherin and fibronectin. In addition, H2A.Z.1 knockdown reduced the in vivo tumor growth rate in a mouse xenograft model. In conclusion, our findings suggest the oncogenic potential of H2A.Z.1 in liver tumorigenesis and that it plays established role in accelerating cell cycle transition and EMT during hepatocarcinogenesis. This makes H2A.Z.1 a promising target in liver cancer therapy. PMID:26863632

  2. 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

  3. Regulation of histone H2A.Z expression is mediated by sirtuin 1 in prostate cancer.

    PubMed

    Baptista, Tiago; Graça, Inês; Sousa, Elsa J; Oliveira, Ana I; Costa, Natália R; Costa-Pinheiro, Pedro; Amado, Francisco; Henrique, Rui; Jerónimo, Carmen

    2013-10-01

    Histone variants seem to play a major role in gene expression regulation. In prostate cancer, H2A.Z and its acetylated form are implicated in oncogenes' upregulation. SIRT1, which may act either as tumor suppressor or oncogene, reduces H2A.Z levels in cardiomyocytes, via proteasome-mediated degradation, and this mechanism might be impaired in prostate cancer cells due to sirtuin 1 downregulation. Thus, we aimed to characterize the mechanisms underlying H2A.Z and SIRT1 deregulation in prostate carcinogenesis and how they interact. We found that H2AFZ and SIRT1 were up- and downregulated, respectively, at transcript level in primary prostate cancer and high-grade prostatic intraepithelial neoplasia compared to normal prostatic tissues. Induced SIRT1 overexpression in prostate cancer cell lines resulted in almost complete absence of H2A.Z. Inhibition of mTOR had a modest effect on H2A.Z levels, but proteasome inhibition prevented the marked reduction of H2A.Z due to sirtuin 1 overexpression. Prostate cancer cells exposed to epigenetic modifying drugs trichostatin A, alone or combined with 5-aza-2'-deoxycytidine, increased H2AFZ transcript, although with a concomitant decrease in protein levels. Conversely, SIRT1 transcript and protein levels increased after exposure. ChIP revealed an increase of activation marks within the TSS region for both genes. Remarkably, inhibition of sirtuin 1 with nicotinamide, increased H2A.Z levels, whereas activation of sirtuin 1 by resveratrol led to an abrupt decrease in H2A.Z. Finally, protein-ligation assay showed that exposure to epigenetic modifying drugs fostered the interaction between sirtuin 1 and H2A.Z. We concluded that sirtuin 1 and H2A.Z deregulation in prostate cancer are reciprocally related. Epigenetic mechanisms, mostly histone post-translational modifications, are likely involved and impair sirtuin 1-mediated downregulation of H2A.Z via proteasome-mediated degradation. Epigenetic modifying drugs in conjunction with

  4. Regulation of histone H2A.Z expression is mediated by sirtuin 1 in prostate cancer

    PubMed Central

    Baptista, Tiago; Graça, Inês; Sousa, Elsa J.; Oliveira, Ana I.; Costa, Natália R.; Costa-Pinheiro, Pedro; Amado, Francisco; Henrique, Rui; Jerónimo, Carmen

    2013-01-01

    Histone variants seem to play a major role in gene expression regulation. In prostate cancer, H2A.Z and its acetylated form are implicated in oncogenes' upregulation. SIRT1, which may act either as tumor suppressor or oncogene, reduces H2A.Z levels in cardiomyocytes, via proteasome-mediated degradation, and this mechanism might be impaired in prostate cancer cells due to sirtuin 1 downregulation. Thus, we aimed to characterize the mechanisms underlying H2A.Z and SIRT1 deregulation in prostate carcinogenesis and how they interact. We found that H2AFZ and SIRT1 were up- and downregulated, respectively, at transcript level in primary prostate cancer and high-grade prostatic intraepithelial neoplasia compared to normal prostatic tissues. Induced SIRT1 overexpression in prostate cancer cell lines resulted in almost complete absence of H2A.Z. Inhibition of mTOR had a modest effect on H2A.Z levels, but proteasome inhibition prevented the marked reduction of H2A.Z due to sirtuin 1 overexpression. Prostate cancer cells exposed to epigenetic modifying drugs trichostatin A, alone or combined with 5-aza-2'-deoxycytidine, increased H2AFZ transcript, although with a concomitant decrease in protein levels. Conversely, SIRT1 transcript and protein levels increased after exposure. ChIP revealed an increase of activation marks within the TSS region for both genes. Remarkably, inhibition of sirtuin 1 with nicotinamide, increased H2A.Z levels, whereas activation of sirtuin 1 by resveratrol led to an abrupt decrease in H2A.Z. Finally, protein-ligation assay showed that exposure to epigenetic modifying drugs fostered the interaction between sirtuin 1 and H2A.Z. We concluded that sirtuin 1 and H2A.Z deregulation in prostate cancer are reciprocally related. Epigenetic mechanisms, mostly histone post-translational modifications, are likely involved and impair sirtuin 1-mediated downregulation of H2A.Z via proteasome-mediated degradation. Epigenetic modifying drugs in conjunction with

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

    PubMed

    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 Mg(2+) ions released during the cell culture indicated that silanization does not affect substrate degradation.

  6. 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.

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

    PubMed Central

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

    2012-01-01

    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. PMID:27877541

  8. 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.

  9. 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.

  10. Thermal stress analysis of fused-cast AZS refractories during production; Part 1: Industrial study

    SciTech Connect

    Cockcroft, S.L.; Brimacombe, J.K. . Centre for Metallurgical Process Engineering); Walrod, D.G.; Myles, T.A. . Monofrax-S Plant)

    1994-06-01

    A study has been conducted to understand and prevent the formation of cracks in alumina-zirconia-silica (AZS) refractory blocks during solidification processing. A fundamental approach has been taken, centered on the development of a three-dimensional mathematical model to predict heat flow and stress generation in fused-cast AZS refractory blocks. In the first part of a two-part study, the voidless'' casting process has been carefully examined in an industrial setting. From a survey of the distribution, frequency of occurrence, and fracture surface morphology of cracks, an attempt was made to link the crack types found in the study to process variables. In-mold temperature data collected for a single casting throughout the normal cooling period have been used to validate the heat-flow model which is described in Part 2. The stress analysis, cause of the different cracks, and remedial action are also presented in Part 2.

  11. 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.

  12. 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.

  13. 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…

  14. Effect of Aging on the Microstructure and Mechanical Properties of Magnesium Alloy AZ31

    NASA Astrophysics Data System (ADS)

    Kerenciler, H.; Gündüz, S.; Erden, M. Akif; Türkmen, M.; Karabulut, H.

    2016-07-01

    The structure and mechanical properties of magnesium alloy AZ31 are studied after conventional and deformation aging under conditions corresponding to the thermal cycle of polymerization in paint coating of cars. The aging is conducted after 3-h solution treatment at 400°C, water quenching, and aging at 180°C for from 10 min to 6 h. Some of the specimens are deformed by 0.5% right after the solution treatment and then aged by the same regime.

  15. Torsional and axial damping properties of the AZ31B-F magnesium alloy

    NASA Astrophysics Data System (ADS)

    Anes, V.; Lage, Y. E.; Vieira, M.; Maia, N. M. M.; Freitas, M.; Reis, L.

    2016-10-01

    Damping properties for the AZ31B-F magnesium alloy were evaluated for pure axial and pure shear loading conditions at room temperature. Hysteretic damping results were measured through stress-strain controlled tests. Moreover, the magnesium alloy viscous damping was measured with frequency response functions and free vibration decay, both results were obtained by experiments. The axial and shear damping ratio (ASDR) has been identified and described, specifically for free vibration conditions.

  16. 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.

  17. 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.

  18. 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.

  19. 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 320°C. 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.

  20. Effect of Surface Modification on Cumulative Tensile Ductility of AZ31 Magnesium Sheet

    NASA Astrophysics Data System (ADS)

    Habibnejad-korayem, Mahdi; Jain, Mukesh K.; Mishra, Raja K.

    2016-12-01

    Wire brushing and annealing (WBA) process was developed, optimized and utilized to modify the surface layer microstructure of AZ31 automotive magnesium sheet material. The process was carried out using softer brass wire brushes to mitigate the effect of wire brushing on surface quality and damage. The influence of modified surface grain structure and crystallographic texture was studied by continuous uniaxial tension test as well as by a newly proposed multi-step uniaxial stretching and annealing (MUSA) process to assess cumulative uniaxial tensile ductility of AZ31 sheet. A rotational speed of 2800 revolutions per minute for the wire brush with a near-zero depth of cut followed by annealing at 473 K (200 °C) for 60 minutes resulted in acceptable surface quality with a refined grain layer of depth 30 μm, and a modified crystallographic texture on the surface. Material flow behavior, grain microstructure, and texture evolution of WBA-processed material during subsequent MUSA process were analyzed to assess the role of wire brushing in enhancing the MUSA response of AZ31 sheet. Original fully annealed AZ31 sheet (in the non-WBA condition) was also subjected to identical MUSA process for comparison purposes. The results showed improvement in terminal uniaxial tensile ductility of WBA-MUSA-processed material compared to Standard-MUSA material. The ductility improvement is attributed to non-basal texture development and re-distribution of the texture, as well as to grain refinement within the highly deformed surface layer from the combination of WBA and MUSA processes.

  1. 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.; Elliott, M.L.

    1996-10-01

    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 were 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 was 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.

  2. 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.

  3. Oklahoma City Revitalization

    EPA Pesticide Factsheets

    Since the beginning of their Brownfields Program in 2003, Oklahoma City has been the recipient of nine EPA Brownfields Grants, creating a new city from the inside out. So far, 45 properties have been assessed and/or remediated.

  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. Characteristics of AZ31 Mg alloy joint using automatic TIG welding

    NASA Astrophysics Data System (ADS)

    Liu, Hong-tao; Zhou, Ji-xue; Zhao, Dong-qing; Liu, Yun-teng; Wu, Jian-hua; Yang, Yuan-sheng; Ma, Bai-chang; Zhuang, Hai-hua

    2017-01-01

    The automatic tungsten-inert gas welding (ATIGW) of AZ31 Mg alloys was performed using a six-axis robot. The evolution of the microstructure and texture of the AZ31 auto-welded joints was studied by optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electron backscatter diffraction. The ATIGW process resulted in coarse recrystallized grains in the heat affected zone (HAZ) and epitaxial growth of columnar grains in the fusion zone (FZ). Substantial changes of texture between the base material (BM) and the FZ were detected. The {0002} basal plane in the BM was largely parallel to the sheet rolling plane, whereas the c-axis of the crystal lattice in the FZ inclined approximately 25° with respect to the welding direction. The maximum pole density increased from 9.45 in the BM to 12.9 in the FZ. The microhardness distribution, tensile properties, and fracture features of the AZ31 auto-welded joints were also investigated.

  6. Flow behaviour of magnesium alloy AZ31B processed by equal-channel angular pressing

    NASA Astrophysics Data System (ADS)

    Arun, M. S.; Chakkingal, U.

    2014-08-01

    Magnesium alloys are characterised by their low density, high specific strength and stiffness. But, the potential application of Mg is limited by its low room-temperature ductility & formability. Formability can be improved by developing an ultrafine grained (UFG) structure. Equal channel angular pressing (ECAP) is a well known process that can be used to develop an ultrafine grained microstructure. The aim of this study was to investigate the flow behaviour of AZ31B magnesium alloy after ECAP. The specimen was subjected to three passes of ECAP with a die angle of 120° using processing route Bc. The processing temperature was 523 K for the first pass and 423 K for the subsequent two passes. The microstructure characterisation was done. Compression tests of ECAPed and annealed specimens were carried out at strain rates of 0.01 - 1s-1 and deformation temperatures of 200 - 300°C using computer servo-controlled Gleeble-3800 system. The value of activation energy Q and the empirical materials constants of A and n were determined. The equations relating flow stress and Zener-Hollomon parameter were proposed. In the case annealed AZ31, the activation energy was determined to be 154 kJ/mol, which was slightly higher than the activation energy of 144 kJ/mol for ECAPed AZ31.

  7. 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.

  8. Microstructure and mechanical properties of Si and Sb added AZ91 magnesium alloy

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

    The effect of Si (individual and combined) with 0.2 pct Sb additions on the microstructure and mechanical properties of permanent mold AZ91 alloy has been studied. The results indicate that Si addition introduces a Chinese script Mg2Si phase at the grain boundary along with the Mg17Al12- β phase and reduces ductility and strength of the alloy both at room and high temperatures. A small amount of Sb addition modifies the Mg2Si phase besides distributing it evenly along the grain boundary. Improved room- and high-temperature mechanical properties are observed in Sb added AZ91+xSi alloys. However, maximum properties are noticed with the alloy having the combined addition of 0.2 silicon and antimony. Fractograpy of tensile- and impact-tested AZ91 alloy shows cleavage and brittle type of failure. Addition of Si reduces the quasi-cleavage planes, whereas Sb addition increases it while also increasing the plastic zone.

  9. 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.

  10. 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 24 h, 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.

  11. H2A.Z Acidic Patch Couples Chromatin Dynamics to Regulation of Gene Expression Programs during ESC Differentiation

    PubMed Central

    Subramanian, Vidya; Mazumder, Aprotim; Surface, Lauren E.; Butty, Vincent L.; Fields, Paul A.; Alwan, Allison; Torrey, Lillian; Thai, Kevin K.; Levine, Stuart S.; Bathe, Mark; Boyer, Laurie A.

    2013-01-01

    The histone H2A variant H2A.Z is essential for embryonic development and for proper control of developmental gene expression programs in embryonic stem cells (ESCs). Divergent regions of amino acid sequence of H2A.Z likely determine its functional specialization compared to core histone H2A. For example, H2A.Z contains three divergent residues in the essential C-terminal acidic patch that reside on the surface of the histone octamer as an uninterrupted acidic patch domain; however, we know little about how these residues contribute to chromatin structure and function. Here, we show that the divergent amino acids Gly92, Asp97, and Ser98 in the H2A.Z C-terminal acidic patch (H2A.ZAP3) are critical for lineage commitment during ESC differentiation. H2A.Z is enriched at most H3K4me3 promoters in ESCs including poised, bivalent promoters that harbor both activating and repressive marks, H3K4me3 and H3K27me3 respectively. We found that while H2A.ZAP3 interacted with its deposition complex and displayed a highly similar distribution pattern compared to wild-type H2A.Z, its enrichment levels were reduced at target promoters. Further analysis revealed that H2A.ZAP3 was less tightly associated with chromatin, suggesting that the mutant is more dynamic. Notably, bivalent genes in H2A.ZAP3 ESCs displayed significant changes in expression compared to active genes. Moreover, bivalent genes in H2A.ZAP3 ESCs gained H3.3, a variant associated with higher nucleosome turnover, compared to wild-type H2A.Z. We next performed single cell imaging to measure H2A.Z dynamics. We found that H2A.ZAP3 displayed higher mobility in chromatin compared to wild-type H2A.Z by fluorescent recovery after photobleaching (FRAP). Moreover, ESCs treated with the transcriptional inhibitor flavopiridol resulted in a decrease in the H2A.ZAP3 mobile fraction and an increase in its occupancy at target genes indicating that the mutant can be properly incorporated into chromatin. Collectively, our work suggests

  12. H2A.Z acidic patch couples chromatin dynamics to regulation of gene expression programs during ESC differentiation.

    PubMed

    Subramanian, Vidya; Mazumder, Aprotim; Surface, Lauren E; Butty, Vincent L; Fields, Paul A; Alwan, Allison; Torrey, Lillian; Thai, Kevin K; Levine, Stuart S; Bathe, Mark; Boyer, Laurie A

    2013-01-01

    The histone H2A variant H2A.Z is essential for embryonic development and for proper control of developmental gene expression programs in embryonic stem cells (ESCs). Divergent regions of amino acid sequence of H2A.Z likely determine its functional specialization compared to core histone H2A. For example, H2A.Z contains three divergent residues in the essential C-terminal acidic patch that reside on the surface of the histone octamer as an uninterrupted acidic patch domain; however, we know little about how these residues contribute to chromatin structure and function. Here, we show that the divergent amino acids Gly92, Asp97, and Ser98 in the H2A.Z C-terminal acidic patch (H2A.Z(AP3)) are critical for lineage commitment during ESC differentiation. H2A.Z is enriched at most H3K4me3 promoters in ESCs including poised, bivalent promoters that harbor both activating and repressive marks, H3K4me3 and H3K27me3 respectively. We found that while H2A.Z(AP3) interacted with its deposition complex and displayed a highly similar distribution pattern compared to wild-type H2A.Z, its enrichment levels were reduced at target promoters. Further analysis revealed that H2A.Z(AP3) was less tightly associated with chromatin, suggesting that the mutant is more dynamic. Notably, bivalent genes in H2A.Z(AP3) ESCs displayed significant changes in expression compared to active genes. Moreover, bivalent genes in H2A.Z(AP3) ESCs gained H3.3, a variant associated with higher nucleosome turnover, compared to wild-type H2A.Z. We next performed single cell imaging to measure H2A.Z dynamics. We found that H2A.Z(AP3) displayed higher mobility in chromatin compared to wild-type H2A.Z by fluorescent recovery after photobleaching (FRAP). Moreover, ESCs treated with the transcriptional inhibitor flavopiridol resulted in a decrease in the H2A.Z(AP3) mobile fraction and an increase in its occupancy at target genes indicating that the mutant can be properly incorporated into chromatin. Collectively, our

  13. 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.

  14. [Healthy Cities projects].

    PubMed

    Takano, Takehito

    2002-05-01

    This is a review article on "Healthy Cities". The Healthy Cities programme has been developed by the World Health Organization (WHO) to tackle urban health and environmental issues in a broad way. It is a kind of comprehensive policy package to carry out individual projects and activities effectively and efficiently. Its key aspects include healthy public policy, vision sharing, high political commitment, establishment of structural organization, strategic health planning, intersectoral collaboration, community participation, setting approach, development of supportive environment for health, formation of city health profile, national and international networking, participatory research, periodic monitoring and evaluation, and mechanisms for sustainability of projects. The present paper covered the Healthy Cities concept and approaches, rapid urbanization in the world, developments of WHO Healthy Cities, Healthy Cities developments in the Western Pacific Region, the health promotion viewpoint, and roles of research.

  15. Mexico City, Mexico

    NASA Technical Reports Server (NTRS)

    1989-01-01

    In this rare clear view of Mexico City, Mexico (19.5N, 99.0W), the network of broad avenues and plazas of the capital city are very evident. The city, built on the remnants of a lake in the caldera of a tremendous extinct volcano, is home to over twenty million people and is slowly sinking as subsidence takes it's toll on the lakebed.

  16. 300 Cities Virtual Experiment

    DTIC Science & Technology

    2009-09-01

    across line items. These differences will provide local, regional, and national comparison data for the next iteration of the Smart Card , an interface...updated weekly)  Tax actions by line item (annual) 15 Incorporated into the Smart Card will be demographic data for each city, simulated...In addition to descriptive city data as above, the Smart Card will contain informative output from our virtual city simulations, and include possibly

  17. 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 β-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.

  18. 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.

  19. 2003 AZ84: Size, shape, albedo and first detection of topographic features

    NASA Astrophysics Data System (ADS)

    Dias-Oliveira, Alex; Sicardy, Bruno; Ortiz, Jose-Luis; Braga-Ribas, Felipe; Vieira-Martins, Roberto; BENEDETTI Rossi, Gustavo; camargo, julio; Assafin, Marcelo; Gomes-Júnior, Altair; Baug, Tapas; Chandrasekhar, Thyagarajan; Duffard, Rene; Ergang, Zhao; Ganesh Ganesh, Shashikiran; Ikari, Yasukazu; Irawati, Puji; Jain, Rajmal; Liying, Zhu; Richichi, Andrea; Shengbang, Qian; Behrend, Raoul; Benkhaldoun, Zouhair; Brosch, Noah; Daassou, Ahmed; Gal-Yam's, Avishay; Garcia-Lozano, Rubén; Gillon, Michael; Jehin, Emmanuel; Kaspi, Shai; Klotz, Alain; Lecacheux, Jean; Mahasena, Putra; Manfroid, Jean; Manulis, Ilan; Maury, Alain; Mohan, Vijay; Morales, Nicolas; Rinner, Claudine; Roques, françoise; Sharma, Amar; Sposetti, Stefano; Tanga, Paolo; Thirouin, Audrey; Vachier, Frederic; Widemann, Thomas

    2016-10-01

    We analyze two multi-chord stellar occultations by the Trans-Neptunian Object (TNO) 2003 AZ84 observed on February 3, 2012 and November 15, 2014.They provide different elliptical limb fits that are consistent to within their respective error bars, but could also suggest a possible precession of the object (assumed here to be a Maclaurin spheroid). The derived equatorial radius and oblateness are Re = 393 ± 7 km and ɛ = 0.057 in 2014 and Re = 414 ± 13 km and ɛ = 0.165 in 2012, respectively. Those results are consistent with single-chord events observed in January 2011 and December 2013. The figures above provide geometric visual albedos of pV(2014) = 0.112 ± 0.008 and pV(2012) = 0.114 ± 0.020. Using the Maclaurin assumption, combined with possible rotational periods of 6.67 h and 10.56 h, we estimate density upper limits of 1.89 ± 0.16g/cm3 and 0.77 ± 0.07g/cm3 for the two dates, respectively.The 2014 event provides (for the first time during a TNO occultation) a grazing chord with a gradual disappearance of the star behind 2003AZ84's limb that lasts for more than 10 seconds. We rule out the possibility of a localized dust concentration as it would imply very high optical depth for that cloud. We favor a local topographic feature (chasm) with minimum width and depth of 22 ± 2.5 km and 7 ± 2.0 km, respectively. Features with similar depths are in fact observed on Pluto's main satellite, Charon, which has a radius of about 605 km, comparable to that of 2003AZ84.

  20. 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.

  1. Molecular cloaking of H2A.Z on mortal DNA chromosomes during nonrandom segregation.

    PubMed

    Huh, Yang Hoon; Sherley, James L

    2011-10-01

    Although nonrandom sister chromatid segregation is a singular property of distributed stem cells (DSCs) that are responsible for renewing and repairing mature vertebrate tissues, both its cellular function and its molecular mechanism remain unknown. This situation persists in part because of the lack of facile methods for detecting and quantifying nonrandom segregating cells and for identifying chromosomes with immortal DNA strands, the cellular molecules that signify nonrandom segregation. During nonrandom segregation, at each mitosis, asymmetrically self-renewing DSCs continuously cosegregate to themselves the set of chromosomes that contain immortal DNA strands, which are the oldest DNA strands. Here, we report the discovery of a molecular asymmetry between segregating sets of immortal chromosomes and opposed mortal chromosomes (i.e., containing the younger set of DNA template strands) that constitutes a new convenient biomarker for detection of cells undergoing nonrandom segregation and direct delineation of chromosomes that bear immortal DNA strands. In both cells engineered with DSC-specific properties and ex vivo-expanded mouse hair follicle stem cells, the histone H2A variant H2A.Z shows specific immunodetection on immortal DNA chromosomes. Cell fixation analyses indicate that H2A.Z is present on mortal chromosomes as well but is cloaked from immunodetection, and the cloaking entity is acid labile. The H2A.Z chromosomal asymmetry produced by molecular cloaking provides a first direct assay for nonrandom segregation and for chromosomes with immortal DNA strands. It also seems likely to manifest an important aspect of the underlying mechanism(s) responsible for nonrandom sister chromatid segregation in DSCs.

  2. 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.

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

    PubMed

    Braszczyńska-Malik, K N; Lityńska, 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.

  4. A study on the boss forming process of AZ31 Mg alloy sheet

    NASA Astrophysics Data System (ADS)

    Park, Ji Eon; Kim, Hyung Rae; Ahn, Sang Ho; Chang, Young Won

    2009-06-01

    A series of boss forming tests has been carried out using an AZ31 Mg alloy sheet at 250 °C, 300 °C, and 350 °C with various lubrication conditions to obtain optimum process conditions. The Mg alloy sheet had a homogeneous distribution of very fine sized grains. Surface defects generated during boss forming process could be reduced by changing the friction conditions, as prescribed by FEM analysis using the DEFORM 2D program. The modified boss forming process, lubricating only on the front side, was found to be successful in manufacturing the boss without defects.

  5. Mechanical properties and structure of AZ61 magnesium alloy processed by equal channel angular pressing

    NASA Astrophysics Data System (ADS)

    Hilšer, O.; Rusz, S.; Tański, T.; Snopiński, P.; Džugan, J.; Kraus, M.

    2017-02-01

    An equal channel angular pressing (ECAP) procedure has been developed to produce a fine-grained AZ61 magnesium alloy. The results show that the microstructure can be effectively refined with increasing equivalent strain during ECAP. For increasing ECAP process efficiency was conventional tool as a helix in the horizontal part of channel built. This fine-grained alloy has an excellent strength accompanied by reasonable good tensile ductility. The success of the development of this ECAP procedure can offer a good opportunity for the development of magnesium alloys with good mechanical properties.

  6. 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

  7. 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.

  8. 77 FR 19610 - Marc Knapp, Inmate #-06450-015, FCI Safford, P.O. Box 9000, Safford, AZ 85548; Order Denying...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-02

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE Bureau of Industry and Security Marc Knapp, Inmate --06450-015, FCI Safford, P.O. Box 9000, Safford, AZ....O. Box 9000, Safford, AZ 85548, and when acting for or on behalf of Knapp, his...

  9. Feasibility of Formation of AZS (Alumina-Zirconia-Silica) Refractory Products with Different Composition to the Commercial Product Through X-Ray Diffraction

    NASA Astrophysics Data System (ADS)

    Guzmán, A. M.; Rodríguez, P.

    The AZS refractory materials with different composition to the commercial product were obtained, and the feasibility of formation of these products was studied taking like departure point the free energy of their formation. The AZS refractories were obtained by a traditional method of producing ceramic materials, the process of sintering.

  10. 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 County, NY

  11. Sustainability for Shrinking Cities

    EPA Science Inventory

    Shrinking cities are widespread throughout the world despite the rapidly increasing global urban population. These cities are attempting to transition to sustainable trajectories to improve the health and well-being of urban residents, to build their capacity to adapt to changing...

  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. Build a City.

    ERIC Educational Resources Information Center

    Reynolds, Jean A.

    1985-01-01

    A week-long build-a-city project is described which lets students become familiar with the history of the five Platonic solids (tetrahedron, octahedron, hexahedron, isosahedron, dodecahedron) and then use these solids to create a city using posterboard and construction paper. (MNS)

  14. 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…

  15. 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

  16. 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)

  17. 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).

  18. 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 μm and ~2-15 μm, 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 ~125-150°C. Elevated temperature bending-under-tension (BUT) friction tests were conducted at 350°C 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.

  19. 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.

  20. 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.

  1. 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.

  2. A cross-shear deformation for optimizing the strength and ductility of AZ31 magnesium alloys

    PubMed Central

    Hamad, Kotiba; Ko, Young Gun

    2016-01-01

    Magnesium alloys have recently attracted great interest due their lightweight and high specific strength. However, because of their hexagonal close-packed structure, they have few active slip systems, resulting in poor ductility and high mechanical anisotropy at room temperature. In the present work, we used a cross-shear deformation imposed by a differential speed rolling (DSR) technique to improve the room temperature strength and ductility of AZ31 magnesium alloy sheets. To introduce the cross-shear deformation, the sheets were rotated 180° around their longitudinal axis between the adjacent passes of DSR. The sheets of the AZ31 alloy subjected to the cross-shear deformation showed a uniform fine microstructure (1.2 ± 0.1 μm) with weak basal textures. The fabricated sheets showed a simultaneous high ultimate tensile strength and elongation-to-failure, i.e., ~333 MPa and ~21%, respectively. These were explained based on the structural features evolved due to the cross-shear deformation by DSR. The high strength was attributed to the uniform fine microstructure, whereas the high ductility was explained based on the basal texture weakening. PMID:27406685

  3. 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.

  4. Effect of aging time and temperature on the aging behavior in Sn containing AZ91 alloy

    NASA Astrophysics Data System (ADS)

    Kim, Jeong Kyun; Oh, Seung Hyun; Kim, Kang Cheol; Kim, Won Tae; Kim, Do Hyang

    2017-03-01

    Effects of aging temperature and time on the aging behavior in AZ91 alloy and Sn containing AZ91 alloy (AZT915) have been investigated in the present study. The mode of precipitation, i.e. discontinuous and continuous precipitation in both alloys is strongly affected by the aging temperature. At low aging temperature of 403 K, only discontinuous precipitation occurs at the grain boundaries, whereas at high aging temperatures of 573 and 623 K only continuous precipitation occurs inside the grains. At intermediate temperature range (443 or 498 K) both discontinuous and continuous precipitation reactions occur. In AZT915, the Mg2Sn particles at the grain boundary effectively reduce the available nucleation sites for discontinuous β precipitates, and slow down the movement of the grain boundary, resulting in suppression of discontinuous precipitation. In addition, increased local lattice strain by the presence of Sn in the α-Mg solid solution matrix accelerates the nucleation of the continuous precipitates at the early stage of aging treatment. Therefore, significantly higher peak hardness can be obtained within a shorter aging time in AZT915.

  5. Effect of aging time and temperature on the aging behavior in Sn containing AZ91 alloy

    NASA Astrophysics Data System (ADS)

    Kim, Jeong Kyun; Oh, Seung Hyun; Kim, Kang Cheol; Kim, Won Tae; Kim, Do Hyang

    2017-02-01

    Effects of aging temperature and time on the aging behavior in AZ91 alloy and Sn containing AZ91 alloy (AZT915) have been investigated in the present study. The mode of precipitation, i.e. discontinuous and continuous precipitation in both alloys is strongly affected by the aging temperature. At low aging temperature of 403 K, only discontinuous precipitation occurs at the grain boundaries, whereas at high aging temperatures of 573 and 623 K only continuous precipitation occurs inside the grains. At intermediate temperature range (443 or 498 K) both discontinuous and continuous precipitation reactions occur. In AZT915, the Mg2Sn particles at the grain boundary effectively reduce the available nucleation sites for discontinuous β precipitates, and slow down the movement of the grain boundary, resulting in suppression of discontinuous precipitation. In addition, increased local lattice strain by the presence of Sn in the α-Mg solid solution matrix accelerates the nucleation of the continuous precipitates at the early stage of aging treatment. Therefore, significantly higher peak hardness can be obtained within a shorter aging time in AZT915.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Thermal stability of bimodal microstructure in magnesium alloy AZ91 processed by ECAP

    SciTech Connect

    Pantělejev, Libor

    2015-09-15

    The changes in microstructure of equal channel angular pressing (ECAP) processed magnesium alloy AZ91 during thermal exposure were studied in this paper. The microstructure stability was investigated by means of electron backscatter diffraction (EBSD), which allowed to measure the changes in grain size, mutual ratio of low-angle boundaries (LABs) to high-angle ones (HABs) and local lattice distortion evaluated by the kernel average misorientation (KAM) parameter. It was found experimentally that the threshold temperature at which significant grain coarsening takes place is 350 °C. No modification to mean grain diameter occurs below this temperature, nonetheless, some changes in LAB and HAB fraction, as well as in local lattice distortion, can be observed. - Highlights: • Thermal stability of bimodal UFG AZ91 alloy was assessed by means of EBSD. • Threshold temperature for pronounced grain coarsening was found at 350 °C. • Below 350 °C increase in LAB fraction and local lattice distortion takes place. • Local lattice distortion (LLD) can be well described using KAM approach. • LLD is influenced by coarsening and precipitation of Mg{sub 17}Al{sub 12} particles.

  11. 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 μs. 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 α phase and Mg17Al12 particles started to dissolve in the surface modified layer of depth ∼15 μm. 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.

  12. Chemical nature of phytic acid conversion coating on AZ61 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Pan, Fusheng; Yang, Xu; Zhang, Dingfei

    2009-07-01

    Phytic acid (PA) conversion coating on AZ61 magnesium alloy was prepared by the method of deposition. The influences of pH, time and PA concentration on the formation process, microstructure and properties of the conversion coating were investigated. Scanning electron microscopy (SEM) was used to observe the microstructure. The chemical nature of conversion coating was investigated by energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) techniques. The corrosion resistance was examined by means of potentiodynamic polarization method. The adhesive ability was tested by score experiments. The results showed that the growth and microstructure of the conversion coatings were all obviously affected by pH, time and PA concentration. In 0.5 mg/ml PA solution with a pH of 5, an optimization conversion coating formed after 20 min immersion time by deposition of PA on AZ61 magnesium alloy surface through chelating with Al 3+. It made the corrosion potential Ecorr of sample shifted positively about 171 mV than that of the untreated sample, and the adhesive ability reached to Grade 1 (in accordance with GB/T 9286).

  13. Effect of microporosity on tensile properties of as-cast AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Lee, Choong Do

    2002-05-01

    In the present study, the effect of microporosity on the tensile properties of as-cast AZ91D magnesium alloy was investigated through experimental observation and numerical prediction. The test specimens were fabricated by die-casting and gravity-casting. For gravity-casting, the inoculation and use of various metallic moulds were applied to obtain a wide range of microporosity. The deficiency of the interdendritic feeding of the liquid phase acted as a dominant mechanism on the formation of the micropores in the Mg-Al-alloys, rather than the evolution of hydrogen gas. Although tensile strength and elongation has a nonlinear and very intensive dependence upon microporosity, the yield strength appeared to have a linear relationship with microporosity. However, it was possible to quantitatively estimate the linear contribution of microporosity on the individual tensile property for a range of microporosity, which was below about 1%. The numerical prediction suggests that the effect of microporosity on fractured strength and elongation decreased as the strain hardening exponent increased. Furthermore, the shape and distribution of micropores may play a more dominant role than local plastic deformation on the tensile behavior of AZ91D alloy.

  14. Fatigue properties of magnesium alloy AZ91 processed by severe plastic deformation.

    PubMed

    Fintová, Stanislava; Kunz, Ludvík

    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.

  15. 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

  16. The city of Ottawa.

    PubMed

    1986-06-01

    As Canada's capital, Ottawa's main business is government. The City of Ottawa is a low-density residential community with an abundance of open space. The unprecedented development boom in the City of Ottawa's industrial, commercial, and residential sectors since 1981 reversed the city's declining population trend and slowed the continuous loss of inner-city residents to suburban neighborhoods and new communities outside the city. Ottawa's population is skewed toward an older population because professionals migrate to the city for work and do not leave as they age. In 1981, 8% of Ottawa's population was over 65 years old; by 2001 this percentage is expected to jump to 20%. Although Ottawa's population declined from 1961 to 1981, the total number of households grew at about 4% annually. The trend toward small household formation is expected to continue with the traditional family taking more and more of a minority position. Average household size declined from 3.2 in 1971 to an estimated 2.2 in 1984. There are approximately 147,100 dwelling units in the City of Ottawa of which 12,000 are nonconventional. A realistic density, excluding government-owned public and open space lands, is 15.6 housing units per acre. About half of all dwelling units are low density. By 1984, the city counted 69 shopping centers with over 4 million square feet of floor space. Ottawa's major employer is the federal government, with about 40% of all jobs within the city being civil service. Employment participation rates have increased signficiantly at just over 70% in 1983, up from 62% in 1971, due largely to increased participation by women. The City of Ottawa leads surrounding areas in per capita income due primarily to the increase in the number of young professionals who make up 1 and 2-person households.

  17. Great cities look small.

    PubMed

    Sim, Aaron; Yaliraki, Sophia N; Barahona, Mauricio; Stumpf, Michael P H

    2015-08-06

    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.

  18. 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

  19. Starrett City energy exchange

    SciTech Connect

    Not Available

    1982-01-01

    The Starrett City/26th Ward Energy Project is a joint effort of Starrett City (a privately owned and operated 5881-unit high rise housing complex located in Brooklyn, NY) and the city of New York Department of Environmental Protection to develop the means to utilize waste-derived energy produced as by-products of municipal waste water treatment. Starrett City, a development of over 20,000 residents with its own schools, shopping and community centers, and power plant, is located directly across the street from the City of New York's 26th Ward Water Pollution Control Plant. Out of five energy exchange options, a cooperative project team recommended three: (1) transmitting all digester gas from the 26th Ward wastewater sewage-treatment facility to Starrett's cogeneration-type total energy plant (TEP), (2) piping hot water from the Starrett TEP to provide space and process heat to the 26th Ward, and (3) pumping treated effluent from the 26th Ward to the TEP to eliminate the need for Starrett's cooling tower. Starrett City assumed all installation and maintenance costs, both on city property and the TEP. Starrett projects a 53$ million saving in fuel costs over the next 20 years. The project will serve as a model for similar energy resource development efforts and offer the rationale for the private sector and municipalities to build together for the future.

  20. F-35A Training Basing Environmental Impact Statement. Volume 2. Appendix D - Comment Response Document. Book 1

    DTIC Science & Technology

    2012-06-01

    Fallon Cliff Litchfield Park AZ 9449 Faltisco Janet Surprise AZ 5902 Falye Shannon Goodyear AZ 4362 Faria Debra Litchfield Park AZ 6403 Faria Patricia...Litchfield Park AZ 4112 Faria Ronald Litchfield Park AZ 7498 Farley Chris Glendale AZ 4327 Farmer Frances Surprise AZ 4442 Farnell Susan Surprise...Goodyear AZ 5510 Hayes Sue Sun City AZ 5276 Hayes Thomas & Joan San Diego CA 12115 Haynes Corrine Peoria AZ 4335 Haynes Ernest Peoria AZ 10523 Hays

  1. 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

  2. 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...

  3. 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 ...

  4. 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...

  5. 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...

  6. 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

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Grain Inspection, Packers and Stockyards Administration Designation for the Owensboro, KY; Bloomington, IL; Iowa Falls, IA; Casa Grande, AZ; Fargo, ND; Grand Forks, ND; and Plainview, TX Areas...

  7. Forming-Limit Diagrams for Magnesium AZ31B and ZEK100 Alloy Sheets at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Antoniswamy, Aravindha R.; Carpenter, Alexander J.; Carter, Jon T.; Hector, Louis G.; Taleff, Eric M.

    2013-11-01

    Modern design and manufacturing methodologies for magnesium (Mg) sheet panels require formability data for use in computer-aided design and computer-aided engineering tools. To meet this need, forming-limit diagrams (FLDs) for AZ31B and ZEK100 wrought Mg alloy sheets were developed at elevated temperatures for strain rates of 10-3 and 10-2 s-1. The elevated temperatures investigated range from 250 to 450 °C for AZ31B and 300 to 450 °C for ZEK100. The FLDs were generated using data from uniaxial tension, biaxial bulge, and plane-strain bulge tests, all carried out until specimen rupture. The unique aspect of this study is that data from materials with consistent processing histories were produced using consistent testing techniques across all test conditions. The ZEK100 alloy reaches greater major true strains at rupture, by up to 60%, than the AZ31B alloy for all strain paths at all temperatures and strain rates examined. Formability limits decrease only slightly with a decrease in temperature, less than 30% decrease for AZ31B and less than 35% decrease for ZEK100 as the temperature decreases from 450 to 300 °C. This suggests that forming processes at 250-300 °C are potentially viable for manufacturing complex Mg components.

  8. Effect of TiN nano-coating on the interface microstructure of carbon fibres-AZ91 alloy composite

    NASA Astrophysics Data System (ADS)

    Olszówka-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.

  9. 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.

  10. 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...

  11. Electrochemical Investigations of Polycaprolactone-Coated AZ31 Mg Alloy in Earle's Balance Salt Solution and Conventional Simulated Body Fluid

    NASA Astrophysics Data System (ADS)

    Wilke, Benjamin M.; Zhang, Lei

    2016-06-01

    Polycaprolactone (PCL) coating has been shown to increase the corrosion resistance of magnesium alloys when exposed to a simulated body fluid. A PCL dip coating was applied to AZ31 Mg alloy. Samples were immersed in both Earle's Balance Salt Solution (EBSS) and conventional simulated body fluids (c-SBF) up to 14 days. Microscopic morphology, electrochemical impedance spectroscopy, and potentiodynamic polarization tests were performed to evaluate the corrosion behavior changes of PCL coatings against immersion times in EBSS and c-SBF as compared to the uncoated AZ31 substrate. PCL-coated samples demonstrated improved corrosion resistance compared to bare AZ31 in both EBSS and c-SBF, indicating that the PCL coating exhibited good corrosion protection of AZ31 in simulated body fluid. Samples immersed in EBSS showed significantly higher electrochemical impedance values and slower corrosion progression as compared to the samples in c-SBF, because of the decreased chloride content and CO2 buffering mechanism of the EBSS.

  12. 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...

  13. 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...

  14. 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... Federal agencies that are final within the meaning of 23 U.S.C. 139(I)(1). The actions relate to the proposed Laughlin-Bullhead City Bridge project in Laughlin, Clark County, Nevada; and in Bullhead...

  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, René 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

  16. Sedimentological characteristics of the surficial deposits of the Jal Az-Zor area, Kuwait

    NASA Astrophysics Data System (ADS)

    Al-Bakri, D.; Kittaneh, W.; Shublaq, W.

    1988-10-01

    The purpose of this article is to discuss the nature and characteristics of the surface geology of the Jal Az-Zor escarpment and the adjacent area, to better understand the sedimentology of desert landforms, and the main factors controlling depositional and diagenetic processes active in this environment. The oldest outcrops along the face of the escarpment are the sand and sandstone sequences of the Mutla and Jal Az-Zor Formations of the Kuwait Group (Neogene). Gravelly deposits of the upper member of the Kuwait Group, Dibdibba Formation (Pleistocene) are restricted to a few hillocks and ridges in the summit area of the escarpment. The Neogene deposits in most of the study area are overlain by a veneer of unconsolidated Holocene sediments. These were classified, according to their morphological setting and field occurrence, into: coastal deposits (intertidal mud, sabkha deposits, and sand dunes) and inland deposits (sand drifts, slope deposits, wadi fills, residual deposits and playa deposits). Wind-born quartzitic sand is the most common Holocene sediment in the study area indicating the dominance of the aeolian processes. Gypsum and carbonate present as cementing materials or in the form of gypcrete and calcrete, respectively, are characteristic sedimentological features of the pre-Holocene deposits. Gypcrete and gypsum cement are abundant in the upper section of the escarpment and decreases downward, whereas the carbonate (calcrete) shows a reverse pattern, i.e., it becomes more dominant in the lower section of the escarpment. The source of sulphate ions in the groundwater that is responsible for the development of gypcrete is believed to be the evaporites in the lower section of the Neogene sequence. The source of ions for the formation of calcrete and calcite cement is less understood due to the lack of significant primary carbonates in the near-surface deposits. It is believed that the nature and distribution of the chemically precipitated material (gypsum

  17. City of Albia, Iowa

    EPA Pesticide Factsheets

    The EPA is providing notice of a proposed Administrative Penalty Assessment against the City of Albia, located at 120 South A Street, Albia, Iowa 52531, for alleged violations at the Waste Water Treatment Plant.

  18. City sewer collectors biocorrosion

    NASA Astrophysics Data System (ADS)

    Ksiażek, 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.

  19. City of Parsons, Kansas

    EPA Pesticide Factsheets

    The EPA is providing notice of a proposed Administrative Penalty Assessment against the city of Parsons, KS, for alleged violations at the wastewater treatment plant located at 1636 22000 Rd, Parsons, KS 67357.

  20. 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)

  1. Gonorrhea infections diagnosed among persons living with HIV/AIDS: identifying opportunities for integrated prevention services in New York City, Washington, DC, Miami/Dade County, and Arizona.

    PubMed

    Taylor, Melanie M; Schillinger, Julia A; Furness, Bruce W; Brewer, Toye; Newman, Daniel R; Pathela, Preeti; Skinner, Julia; Braunstein, Sarah; Shepard, Colin; Ahmed, Tashrik; Griffin, Angelique; Blank, Susan; Peterman, Thomas A

    2013-09-01

    : Persons living with HIV/AIDS who acquire new sexually transmitted diseases (STDs) pose a risk for enhanced transmission of both HIV and STDs. To describe the frequency of HIV coinfection among gonorrhea cases (GC), HIV and GC surveillance databases (2000-2008) were cross-matched in New York City (NYC), Washington, DC (DC), Miami/Dade County (MDC), and Arizona (AZ). During 2000-2008, 4.6% (9471/205,689) of reported GCs occurred among persons with previously diagnosed HIV: NYC (5.5%), DC (7.3%), MDC (4%), and AZ (2%). The overall HIV-GC coinfection rates increased over the study period in all 4 sites. Real-time data integration could allow for enhanced prevention among persons with HIV infection and acute STDs.

  2. The opposing nanoscale and macroscale effects of selected nanoparticle addition to AZ91/ZK60A hybrid magnesium alloy

    NASA Astrophysics Data System (ADS)

    Paramsothy, Muralidharan; Gupta, Manoj

    2013-09-01

    B4C and AlN nanoparticles were separately added to solidification processed AZ91/ZK60A hybrid magnesium alloy to improve tensile and compressive properties. In tension, both nanoparticles strengthened the hybrid alloy. However, only B4C nanoparticle addition significantly improved the ductility of the hybrid alloy, while AlN nanoparticle addition slightly decreased the ductility of the hybrid alloy. Comparing both nanocomposites as well as monolithic alloy, there was no significant difference in the grain size or crystallographic texture. However, it was possible that the AlN nanoparticle was more chemically reactive with the alloy matrix compared to the B4C nanoparticle. Also, it was observed that unlike AlN nanoparticle addition, B4C nanoparticle addition enabled the formation of numerous nanoscale stacking faults in the hybrid alloy matrix. Further, it was apparent that the B4C nanoparticle promoted the nanoscale precipitation of Al12Mg17 intermetallic particles (with particle coarsening thereafter), whereas the AlN nanoparticle did not alter the intermetallic precipitation characteristics in the alloy matrix. Consequently, nano/micro-particle induced high strain zone (HSZ) formation during tensile deformation was more pronounced in the AZ91/ZK60A/B4C nanocomposite compared to the AZ91/ZK60A/AlN nanocomposite, rendering the B4C nanoparticle significantly greater capability (compared to the AlN nanoparticle) in enhancing the tensile ductility of the hybrid alloy. The promotion of nanoscale precipitation of Al12Mg17 intermetallic particles (with particle coarsening thereafter) by the B4C nanoparticle also enabled the AZ91/ZK60A/B4C nanocomposite to have significantly higher compressive strength (per strain level during deformation) compared to the AZ91/ZK60A/AlN nanocomposite.

  3. 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.

  4. 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.

  5. [Cities in peril, Mahgreb].

    PubMed

    Naciri, M

    1994-10-01

    The urban population has surpassed 50% in the Maghreb: first in Tunisia, followed by Algeria and Morocco. This phenomenon has greatly affected the distribution of power and the forms of its exercise in the political, social, and economic domain. The old city social strata are becoming extinct while city management is falling more and more under the control of cadres originally from rural areas. Urbanization is occurring at a slower pace than in other developing countries, however. In Morocco, the small- and medium-sized towns are growing at a faster rate than the cities. Their lack of infrastructure and services, like those that exist in the periphery of large cities, preoccupies the small- and medium-sized towns. The urban explosion is much more contained than its management is adapting. Legal and illegal housing will dominate the Moroccan city in the future. In the last decade, Moroccan authorities have tried to establish mechanisms to integrate populations in slums and illegal housing with the urban space. The Tunisians are also working on this. In Algeria, the rigid, urban formal management leaves no room to develop any type of housing. The problem of housing is even more grave here than the other 2 countries. Structural adjustment policies promote selling rather than renting houses. The government is not involved in social and health services. Algeria has a 2-tier society: a minority involved in the private sector and the majority who depends on the collapsing public sector which cannot meet the great needs of the poor. Persons with college degrees are unemployed in Algeria. One no longer knows how to build towns with the traditional medinas. The transportation system is falling apart in cities. Cities dump liquid and solid wastes directly into the sea or the wadis. The major risk of maghrebian cities lies in socioeconomic inequalities.

  6. 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.

  7. Fatigue and material characteristics of a hot-formed AZ31 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Suh, Chang-Min; Hor, Kwang-Ho; Nahm, Seung-Hoon; Suh, Min-Soo

    2015-03-01

    Magnesium alloys are known to be hard-forming materials at room temperature owing to their material structure. This study analyzes the optimal temperature conditions of warm-forming and the forming process by using a high-pressure laminating test and FM analysis, respectively. The effect of temperatures on the fatigue limit was examined from the collected specimens by analyzing the material properties after the fatigue test. The material formed at a temperature of 230°C shows occasional defects, but the best forming quality was obtained at 270°C. The optimal temperature for the forming process was found to be 250°C considering the material quality and thermal efficiency. The overall fatigue life of specimens decreases with an increase in the processing temperature. The fatigue limit of AZ31 formed at 250°C was approximately 100 MPa after 106 cycles.

  8. Microstructure and Texture Evolution During the Alternate Extrusion of an AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Li, Feng; Jiang, Hong Wei; Liu, Yang

    2017-01-01

    In this study, a new extrusion process, alternate extrusion (AE), is proposed. We evaluated the reliability and superiority of this process in practical applications by conducting a simulation using the finite element method, which confirmed the experimental results. The microstructure characteristics of an AZ31 magnesium alloy produced by conventional extrusion (CE) and AE were investigated by electron backscattered diffraction and optical microscopy, and the effects of the microstructures on the mechanical properties were studied across the extruded specimens. The main advantage of AE is that the load is reduced to less than half that in the CE process; this results from the reduced cross-section of the split punches. Additionally, the grain size with AE is more refined than with CE because of the additional shear force, which improves the mechanical properties of the alloys. Furthermore, AE can also weaken the intensity of the basal plane texture.

  9. Damage and Failure Analysis of AZ31 Alloy Sheet in Warm Stamping Processes

    NASA Astrophysics Data System (ADS)

    Zhao, P. J.; Chen, Z. H.; Dong, C. F.

    2016-07-01

    In this study, a combined experimental-numerical investigation on the failure of AZ31 Mg alloy sheet in the warm stamping process was carried out based on modified GTN damage model which integrated Yld2000 anisotropic yield criterion. The constitutive equations of material were implemented into a VUMAT subroutine for solver ABAQUS/Explicit and applied to the formability analysis of mobile phone shell. The morphology near the crack area was observed using SEM, and the anisotropic damage evolution at various temperatures was simulated. The distributions of plastic strain, damage evolution, thickness, and fracture initiation obtained from FE simulation were analyzed. The corresponding forming limit diagrams were worked out, and the comparison with the experimental data showed a good agreement.

  10. 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)

  11. 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 β-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 300°C because more lamellar β-Mg17(Al,Zn)12 intermetallic compounds were distributed at the α-Mg grain boundaries and no cracks and pores formed in the FZ of the welded joint.

  12. Effects of Microstructure and Processing Methods on Creep Behavior of AZ91 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Shahbeigi Roodposhti, Peiman; Sarkar, Apu; Murty, Korukonda L.; Scattergood, Ronald O.

    2016-09-01

    This review sheds light on the creep properties of AZ91 magnesium alloys with a major emphasis on the influence of microstructure on the creep resistance and underlying creep deformation mechanism based on stress exponent and activation energy. Effects of processing routes such as steel mold casting, die casting, and thixoforming are considered. Roles of a wide range of additional alloying elements such as Si, Sb, Bi, Ca, Sn, REs, and combined addition of them on the microstructure modification were investigated. The reaction between these elements and the Mg or Al in the matrix develops some thermally stable intermetallic phases which improves the creep resistance at elevated temperatures, however does not influence the creep mechanism.

  13. Initiation of fatigue cracks in AZ91 Mg alloy processed by ECAP

    NASA Astrophysics Data System (ADS)

    Fintová, 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.

  14. 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; Müller, 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.

  15. Process Influences on Laser-beam Melting of the Magnesium Alloy AZ91

    NASA Astrophysics Data System (ADS)

    Schmid, Dominik; Renza, Johanna; Zaeh, Michael F.; Glasschroeder, Johannes

    Magnesium's great lightweight potential and high biocompatibility render laser-beam melting of this metal increasingly interesting. Despite recent research activities in this field, the properties thereby achieved are still inadequate for industrial or medical use. Low surface quality caused by powder sintered to parts' boundaries is one of the main problems. This effect is discussed theoretically and examined on single tracks of the magnesium alloy AZ91. Welding-penetration depth and width was measured on a magnesium plate with and without a powder layer. For the derivation of suitable process parameters, structures with incrementally increasing hatch distances were built and microscopically analyzed. The influence on defect percentage and hardness of the parts was determined based on specimens manufactured with different layer thicknesses. The influence of the oxygen content on solids was analyzed by varying the process atmosphere.

  16. Tribological properties of heat-treated electroless Ni-P coatings on AZ91 alloy

    NASA Astrophysics Data System (ADS)

    Novák, M.; Vojtěch, D.; Novák, P.; Vítů, 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.

  17. Optimization of Wear Behavior of Magnesium Alloy AZ91 Hybrid Composites Using Taguchi Experimental Design

    NASA Astrophysics Data System (ADS)

    Girish, B. M.; Satish, B. M.; Sarapure, Sadanand; Basawaraj

    2016-06-01

    In the present paper, the statistical investigation on wear behavior of magnesium alloy (AZ91) hybrid metal matrix composites using Taguchi technique has been reported. The composites were reinforced with SiC and graphite particles of average size 37 μm. The specimens were processed by stir casting route. Dry sliding wear of the hybrid composites were tested on a pin-on-disk tribometer under dry conditions at different normal loads (20, 40, and 60 N), sliding speeds (1.047, 1.57, and 2.09 m/s), and composition (1, 2, and 3 wt pct of each of SiC and graphite). The design of experiments approach using Taguchi technique was employed to statistically analyze the wear behavior of hybrid composites. Signal-to-noise ratio and analysis of variance were used to investigate the influence of the parameters on the wear rate.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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…

  4. Friction Stir Welded AZ31 Magnesium Alloy: Microstructure, Texture, and Tensile Properties

    NASA Astrophysics Data System (ADS)

    Chowdhury, S. H.; Chen, D. L.; Bhole, S. D.; Cao, X.; Wanjara, P.

    2013-01-01

    This study was aimed at characterizing the microstructure, texture and tensile properties of a friction stir welded AZ31B-H24 Mg alloy with varying tool rotational rates and welding speeds. Friction stir welding (FSW) resulted in the presence of recrystallized grains and the relevant drop in hardness in the stir zone (SZ). The base alloy contained a strong crystallographic texture with basal planes (0002) largely parallel to the rolling sheet surface and < {11bar{2}0} rangle directions aligned in the rolling direction (RD). After FSW the basal planes in the SZ were slightly tilted toward the TD determined from the sheet normal direction (or top surface) and also slightly inclined toward the RD determined from the transverse direction (or cross section) due to the intense shear plastic flow near the pin surface. The prismatic planes (10bar{1}0) and pyramidal planes (10bar{1}1) formed fiber textures. After FSW both the strength and ductility of the AZ31B-H24 Mg alloy decreased with a joint efficiency in-between about 75 and 82 pct due to the changes in both grain structure and texture, which also weakened the strain rate dependence of tensile properties. The welding speed and rotational rate exhibited a stronger effect on the YS than the UTS. Despite the lower ductility, strain-hardening exponent and hardening capacity, a higher YS was obtained at a higher welding speed and lower rotational rate mainly due to the smaller recrystallized grains in the SZ arising from the lower heat input.

  5. Microstructure Refinement After the Addition of Titanium Particles in AZ31 Magnesium Alloy Resistance Spot Welds

    NASA Astrophysics Data System (ADS)

    Xiao, L.; Liu, L.; Esmaeili, S.; Zhou, Y.

    2012-02-01

    Microstructural evolution of AZ31 magnesium alloy welds without and with the addition of titanium powders during resistance spot welding was studied using optical microscopy, scanning electron microscopy, and transmission electron microscopy (TEM). The fusion zone of AZ31 magnesium alloy welds could be divided into columnar dendritic zone (CDZ) and equiaxed dendritic zone (EDZ). The well-developed CDZ in the vicinity of the fusion boundary was clearly restricted and the coarse EDZ in the central region was efficiently refined by adding titanium powders into the molten pool, compared with the as-received alloy welds. A microstructural analysis showed that these titanium particles of approximately 8 µm diameter acted as inoculants and promoted the nucleation of α-Mg grains and the formation of equiaxed dendritic grains during resistance spot welding. Tensile-shear testing was applied to evaluate the effect of titanium addition on the mechanical properties of welds. It was found that both strength and ductility of magnesium alloy welds were increased after the titanium addition. A TEM examination showed the existence of an orientation matching relationship between the added Ti particles and Mg matrix, i.e., [ {0 1bar{1}0} ]_{{Mg}} // [ { 1bar{2} 1bar{3}} ]_{{Ti}} {{and}} ( {000 2} )_{{Mg}} // ( 10bar{1}0)_{{Ti}} in some grains of Ti polycrystal particles. This local crystallographic matching could promote heterogeneous nucleation of the Mg matrix during welding. The diameter of the added Ti inoculant should be larger than 1.8 µm to make it a potent inoculant.

  6. 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.

  7. 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.

  8. 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 β-phase (Mg17Al12) precipitates surrounded by α + β lamellar eutectic in α-Mg solid solution. The AZ91D-T4 specimens showed small β-phase precipitates along the grain boundaries and regions of eutectic mixture. The T6 heat treatment causes the β-phase platelets in the α + β eutectic to grow and develop into β-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 β-precipitates resulting in increased energy absorption in comparison to the quasi-static compression.

  9. SAS-mediated acetylation of histone H4 Lys 16 is required for H2A.Z incorporation at subtelomeric regions in Saccharomyces cerevisiae

    PubMed Central

    Shia, Wei-Jong; Li, Bing; Workman, Jerry L.

    2006-01-01

    The yeast SAS (Something About Silencing) complex and the histone variant H2A.Z have both previously been linked to an antisilencing function at the subtelomeric regions. SAS is an H4 Lys 16-specific histone acetyltransferase complex. Here we demonstrate that the H4 Lys 16 acetylation by SAS is required for efficient H2A.Z incorporation near telomeres. The presence of H4 Lys 16 acetylation and H2A.Z synergistically prevent the ectopic propagation of heterochromatin. Overall, our data suggest a novel antisilencing mechanism near telomeres. PMID:16980580

  10. 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

  11. 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 δ87Sr Proterozoic or Tertiary crystalline rock and, possibly, Tertiary sedimentary rock. Reducing conditions indicated by 234U/238U and δ34S concentrations suggest the groundwater is confined and/or derived from greater depths while carbon isotopes indicate the groundwater is old. Lighter δD and δO-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 δD and δO-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

  12. 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

  13. Building functional cities.

    PubMed

    Henderson, J Vernon; Venables, Anthony J; Regan, Tanner; Samsonov, Ilia

    2016-05-20

    The literature views many African cities as dysfunctional with a hodgepodge of land uses and poor "connectivity." One driver of inefficient land uses is construction decisions for highly durable buildings made under weak institutions. In a novel approach, we model the dynamics of urban land use with both formal and slum dwellings and ongoing urban redevelopment to higher building heights in the formal sector as a city grows. We analyze the evolution of Nairobi using a unique high-spatial resolution data set. The analysis suggests insufficient building volume through most of the city and large slum areas with low housing volumes near the center, where corrupted institutions deter conversion to formal sector usage.

  14. 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.

  15. The histone variant H2A.Z is dynamically expressed in the developing mouse placenta and in differentiating trophoblast stem cells.

    PubMed

    Kafer, Georgia R; Carlton, Peter M; Lehnert, Sigrid A

    2015-11-01

    The histone variant H2A.Z is important in establishing new chromatin environments necessary for permitting changes in gene expression and thus differentiation in mouse embryonic stem (mES) cells. In this study we show that H2A.Z is highly expressed in the early mouse placenta, and is specifically limited to progenitor-like trophoblast cells. Using in vitro models, we revealed distinct differences in H2A.Z abundance between undifferentiated, differentiating and differentiated mouse trophoblast stem (mTS) cells. Our work supports the hypothesis that in addition to roles in differentiating mES cells, H2A.Z is also involved in the differentiation of extra-embryonic tissues.

  16. In vitro and in vivo metabolism of 14C-AZ11, a novel inhibitor of bacterial DNA gyrase/type II topoisomerase.

    PubMed

    Guo, Jian; Joubran, Camil; Luzietti, Ricardo A; Zhou, Fei; Basarab, Gregory S; Vishwanathan, Karthick

    2015-02-01

    1. (2R,4S,4aS)-11-Fluoro-2,4-dimethyl-8-((S)-4-methyl-2-oxooxazolidin-3-yl)-2,4,4a,6-tetrahydro-1H,1'H-spiro [isoxazolo[4,5-g][1,4]oxazino[4,3-a]quinoline-5,5'-pyrimidine]-2',4',6'(3'H)-trione (AZ11) is a novel mode-of-inhibition bacterial topoisomerase inhibitor that entered preclinical development for the treatment of Gram-positive bacteria infection. 2. The in vitro biotransformation studies of AZ11 using mouse, rat, dog and human hepatocytes showed low-intrinsic clearance in all species attributed to microsomal metabolism. 3. After a single intravenous administration of [14C]AZ11 in bile duct cannulated rats, the mean percentage of dose recovered in rat urine, bile and feces was approximately 18, 36 and 42%, respectively. Unchanged AZ11 recovered in rat urine and bile was less than 9% of the dose, indicating that AZ11 underwent extensive metabolism in rats. 4. The most abundant in vivo metabolite detected in urine and bile was M1 formed via ring opening on the piperidine and morpholine rings accounting for 20% of the administered dose. The major fecal metabolite was M5, which accounted for approximately 32% of administered dose. M5 was not formed when AZ11 incubated with rat intestinal microsomes and cytosol but was formed when incubated with fresh rat feces, suggesting that unchanged AZ11 was directly excreted into gut lumen where M5 formed as an intestinal microflora-mediated product. This process could have significant impact on bioavailability or exposure of AZ11 in rat.

  17. City of Crystal City, Missouri - Clean Water Act Public Notice

    EPA Pesticide Factsheets

    The EPA is providing notice of proposed Administrative Penalty Assessment against the City of Crystal City, Missouri, a municipality located in Jefferson County, Missouri, 63019, for alleged violations associated with the City’s wastewater treatment progra

  18. Effects of Extrusion-Shear Process Conditions on the Microstructures and Mechanical Properties of AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Hu, H. J.; Li, Y. Y.; Wang, X.; Zhang, D. F.; Yang, M. B.

    2016-11-01

    In this paper, the effects of extrusion-shear (ES) on the microstructures and mechanical properties of AZ31 magnesium alloy has been studied, which has been achieved by conducting a lot of experiments and tests, including ES process, direct extrusion with different billet temperatures, microstructure analysis, hardness test, tensile & compression tests. The results show that the ES-processed rods has higher strengths (yield strength and tensile strength) than the direct extrusion ones with the same billet temperature, which contributed to their lower averaged grain size obtained from microstructure analysis according to Hall-Petch relation. Besides, the hardness of ES-processed AZ31 magnesium alloy decreases with the increasing of billet temperature. By comparing the two processes, it can be seen that the ES process could refine the microstructure and improve the mechanical properties of magnesium alloy.

  19. Thermal stress analysis of fused-cast AZS refractories during production; Part 2: Development of thermo-elastic stress model

    SciTech Connect

    Cockcroft, S.L.; Brimacombe, J.K. . Centre for Metallurgical Process Engineering); Walrod, D.G.; Myles, T.A. . Monofrax-S Plant)

    1994-06-01

    Mathematical models of heat flow and thermo-elastic stress, based on the finite-element method, have been developed and utilized to analyze the voidless,'' fused-cast, AZS, solidification process. The results of the mathematical analysis, in conjunction with information obtained in a comprehensive industrial study, presented in Part 1 of this paper, describe the mechanisms for the formation of the various crack types found in the fused-cast product. Thermal stresses are generated early in the solidification process by rapid cooling of the refractory surface as it contacts the initially cool mold and later in conjunction with the tetragonal-to-monoclinic phase transformation which occurs in the zirconia component of the AZS refractory. Applying this model, castings were made using a revised mold design. Preliminary results indicate these castings to be free of objectionable transverse cracks.

  20. 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.

  1. 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).

  2. 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.

  3. 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.

  4. A Crystalline Plasticity Finite Element Method for Simulation of the Plastic Deformation of AZ31 Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    Li, Dayong; Zhang, Shaorui; Tang, Weiqin; Huang, Shiyao; Peng, Yinghong

    2010-06-01

    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.

  5. 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

  6. Pea Broth Enhances the Biocontrol Efficacy of Lysobacter capsici AZ78 by Triggering Cell Motility Associated with Biogenesis of Type IV Pilus

    PubMed Central

    Tomada, Selena; Puopolo, Gerardo; Perazzolli, Michele; Musetti, Rita; Loi, Nazia; Pertot, Ilaria

    2016-01-01

    Bacterial cells can display different types of motility, due to the presence of external appendages such as flagella and type IV pili. To date, little information on the mechanisms involved in the motility of the Lysobacter species has been available. Recently, L. capsici AZ78, a biocontrol agent of phytopathogenic oomycetes, showed the ability to move on jellified pea broth. Pea broth medium improved also the biocontrol activity of L. capsici AZ78 against Plasmopara viticola under greenhouse conditions. Noteworthy, the quantity of pea residues remaining on grapevine leaves fostered cell motility in L. capsici AZ78. Based on these results, this unusual motility related to the composition of the growth medium was investigated in bacterial strains belonging to several Lysobacter species. The six L. capsici strains tested developed dendrite-like colonies when grown on jellified pea broth, while the development of dendrite-like colonies was not recorded in the media commonly used in motility assays. To determine the presence of genes responsible for biogenesis of the flagellum and type IV pili, the genome of L. capsici AZ78 was mined. Genes encoding structural components and regulatory factors of type IV pili were upregulated in L. capsici AZ78 cells grown on the above-mentioned medium, as compared with the other tested media. These results provide new insight into the motility mechanism of L. capsici members and the role of type IV pili and pea compounds on the epiphytic fitness and biocontrol features of L. capsici AZ78. PMID:27507963

  7. 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

  8. 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.

  9. Comparison Study II: Double Star Measurements Made Using an Equatorial Mounted Refractor and an Alt-Az Mounted Reflector

    NASA Astrophysics Data System (ADS)

    Frey, Thomas G.; Coombs, Lee C.

    2012-07-01

    Eight double stars with separations between 13 and 48 arc seconds were studied. Their separations and position angles were measured using an equatorial mounted refractor and and alt-az mounted reflector. A 2x Barlow lens was used along with a Celestron Micro Guide eyepiece to magnify the separation. Comparison of the possible effect of magnitude difference on the separation and position angle measurements was investigated.

  10. 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.

  11. 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 300°C for up to four passes using route Bc. Grain refinement from a starting size of 46μm to a grain size distribution of 1-5μm 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.

  12. 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.

  13. 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,…

  14. 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…

  15. Utah: Salt Lake City

    Atmospheric Science Data Center

    2014-05-15

    ... mountains surrounding Salt Lake City are renowned for the dry, powdery snow that results from the arid climate and location at the ... should be used with the red filter placed over your left eye. The canyons and peaks of the Uinta and Wasatch Mountains are ...

  16. 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…

  17. CITIES AND SCHOOLS.

    ERIC Educational Resources Information Center

    CLEMENTS, H. MILLARD

    THIS DISCUSSION OF URBAN EDUCATION BRIEFLY ANALYZES THE OPERATIONAL FRAMEWORK OF LARGE CITIES AND SCHOOLS. IT IS FELT THAT THE PRESENT EDUCATIONAL SYSTEM, WHICH PROVIDES ONLY ONE FORM OF EDUCATION FOR ALL PUPILS, INCONGRUOUSLY REFLECTS THE ADHERENCE TO ESTABLISHED VALUES, LIMITED OPPORTUNITY FOR CHOICE, AND GENERAL ROUTINIZATION WHICH ARE…

  18. 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.

  19. Nature in the City.

    ERIC Educational Resources Information Center

    Ferbert, Mary Lou

    1981-01-01

    Describes a science program developed by the Cleveland Museum of Natural History, "Nature in the City," in which students and teachers learn together about the natural community surrounding their school. Includes program's rationale, list of "adventures," and methods. Discusses strategies of Sherlock Holmes'"adventure" focusing on animal tracks…

  20. 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)

  1. 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)

  2. Nature in the City.

    ERIC Educational Resources Information Center

    Karl, Dorie

    1979-01-01

    Graduate forestry students from Yale University cooperate with the New Haven public school system and with youth organizations to present learning experiences in ecology and the environment to inner city children. The program has been operating successfully for ten years. (RE)

  3. 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)

  4. [City and County Records.

    ERIC Educational Resources Information Center

    Combs, Judith O.; And Others

    Six papers presented at the Institute were concerned with city and county records. They are: "EWEB and Its Records," which discusses the history, laws and records of the Eugene Water and Electric Board (EWEB);""Police Records: Eugene, Oregon," classifies police records, other than administrative, into three general…

  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. 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,…

  7. 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…

  8. 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…

  9. Microstructural effects on the spall properties of ECAE and SWAP magnesium alloys: AZ31B-4E and AMX602

    NASA Astrophysics Data System (ADS)

    Williams, C. L.; Farbaniec, L.; Kecskes, L.; Bradley, J.

    2017-01-01

    The effects of microstructure on the spall properties of two magnesium alloys fabricated via Equal-Channel Angular Extrusion (ECAE) and Spinning Water Atomization Process (SWAP) were investigated. The Hugoniot Elastic Limit (HEL) for both AZ31B-4E and AMX602 magnesium alloys were found to be approximately 0.181±0.003 GPa and 0.187±0.012 GPa, respectively. The spall strengths extracted from the free surface velocity profiles were found to decrease by approximately 4% for AZ31B-4E between 1.7 GPa to 4.6 GPa shock stress. Although this reduction in spall strength may lie within the experimental error, the microstructure of the post-shocked magnesium alloy show that manganese intermetallic inclusions in the AZ31B-4E magnesium were perhaps responsible for the reduction in spall strength as a function of shock stress. On the contrary, the spall strength for AMX602 was found to be random for the same shock stress range studied. This random behavior of the AMX602 was likely due to the incomplete sintering during mechanical processing. The fracture surfaces of both materials were dominated by nanovoids and the AMX602 fracture surface was found to be striated. A more in-depth study is needed to better understand the spall behavior of both materials.

  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.

    2016-03-01

    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. The fluoride coated AZ31B magnesium alloy improves corrosion resistance and stimulates bone formation in rabbit model.

    PubMed

    Sun, Wei; Zhang, Guangdao; Tan, Lili; Yang, Ke; Ai, Hongjun

    2016-06-01

    This study aimed to evaluate the effect of fluorine coated Mg alloy and clarify its mechanism in bone formation. We implanted the fluorine coated AZ31B Mg alloy screw (group F) in rabbit mandibular and femur in vivo. Untreated AZ31B Mg alloy screw (group A) and titanium screw (group T) were used as control. Then, scanning electron microscopy, the spectral energy distribution analysis, hard and decalcified bone tissues staining were performed. Immunohistochemistry was employed to examine the protein expressions of bone morphogenetic protein 2 (BMP-2) and collagen type I in the vicinity of the implant. Compared with the group A, the degradation of the alloy was reduced, the rates of Mg corrosion and Mg ion release were slowed down, and the depositions of calcium and phosphate increased in the group F in the early stage of implantation. Histological results showed that fluorine coated Mg alloy had well osteogenic activity and biocompatibility. Moreover, fluoride coating obviously up-regulated the expressions of collagen type I and BMP-2. This study confirmed that the fluorine coating might improve the corrosion resistance of AZ31B Mg alloy and promote bone formation by up-regulated the expressions of collagen type I and BMP-2.

  12. 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.

  13. Effect of cw-CO2 laser surface treatment on structure and properties of AZ91 magnesium alloy

    NASA Astrophysics Data System (ADS)

    Iwaszko, Józef; Strzelecka, Monika

    2016-06-01

    In the study, samples of AZ91 magnesium alloy were subjected to a surface remelting treatment by means of a continuous wave (cw) CO2 laser. The scope of the investigation included both macro- and microstructural examination, hardness measurements, and wear resistance tests. The investigation has shown that remelting treatment leads to a strong refinement of structure in the surface layer and a more even distribution of phases. Fine α-phase dendrites have been observed to dominate in the remelting zone. The dendritic arm spacing in the laser treated surface was in the range of 1-2.5 μm. The structural changes triggered by remelting have contributed to an increase in the hardness and the wear resistance of AZ91 alloy. The microhardness of the remelted zone has increased to 71-93 HV0.05 for single-strip remelting and to 84-107 HV0.05 for multi-strip remelting in comparison with about ~60 HV0.05 for untreated alloy. The friction coefficient has decreased from 0.375 for material w/o treatment to 0.311 for remelted material. SEM investigations of samples after tribological tests have revealed the presence of parallel grooves proving the occurrence of microploughing and micro cutting of the material during the tribological testing. The results of the conducted investigation have indicated a beneficial influence of the cw-CO2 laser remelting treatment on the structure and properties of AZ91 alloy.

  14. 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.

  15. 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 22±1°C. 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.

  16. Synthesis and properties of hydroxyapatite-containing coating on AZ31 magnesium alloy by micro-arc oxidation

    NASA Astrophysics Data System (ADS)

    Tang, Hui; Han, Yu; Wu, Tao; Tao, Wei; Jian, Xian; Wu, Yunfeng; Xu, Fangjun

    2017-04-01

    In this study, hydroxyapatite-containing coatings were prepared by microarc oxidation on AZ31 magnesium alloy surface to improve its biodegradation performance. Five applied voltages were chosen to prepare the MAO coatings. The results demonstrate that the number of micropores in the films increases but their dimensions decrease after higher voltage is applied. As the surface roughness of the MAO coatings increases with the applied voltage, the wettability of the coatings improves continuously. The MAO coatings were mainly composed of magnesium oxide (MgO) and hydroxyapatite. The amount of hydroxyapatite phase increased with increasing voltage that was applied. The bonding strength became slightly weaker after a higher voltage was applied. But the bonding strengths of all the coatings were consistently higher than 37 MPa, which met the requirement of implant biomaterials. All coatings exhibited higher corrosion resistances and lower hydrogen evolution rate than the bare AZ31 Mg substrate, implying that the degradation rate of the AZ31 Mg alloy was enhanced by the hydroxyapatite-containing coatings. The results indicate that the present treatment of applying hydroxyapatite-containing coatings is a promising technique for the degradable Mg-based biomaterials for orthopedic applications.

  17. Electrophoretic painting on AZ31 Mg alloy pretreated in cerium conversion coating solutions prepared in ethanol-water mixtures

    NASA Astrophysics Data System (ADS)

    Van Phuong, Nguyen; Fazal, Basit Raza; Moon, Sungmo

    2017-01-01

    Electrophoretic painting (E-paint) was prepared on AZ31 Mg alloy samples pretreated in cerium conversion coating (CeCC) solutions with various ratios of ethanol and water mixture and its characteristics, adhesion and corrosion resistance were investigated. It was found that CeCC formed on AZ31 Mg alloy in a CeCC solution without ethanol was partly cracked structure and mainly consisted of Mg(OH)2/MgO, which exhibited weak adhesion with E-painting layer after water immersion test, and low corrosion resistance, as indicated by rapid formation of blisters and paint delamination during salt spray test. The addition of ethanol promoted the growth of a fine nano-crystalline CeO2 layer over the entire substrate surface. The E-paint on AZ31 pretreated in the CeCC solutions with addition of ethanol showed also improved corrosion resistance, as represented by the delayed time for paint delamination and blister formation. The E-paint layers on the CeCC layers formed in solutions containing 50-80 vol% ethanol showed stronger adhesion and better corrosion resistance than those formed on the samples treated in a non-ethanol containing CeCC solution.

  18. 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 10⁷ cycles in air compared to 20MPa at 10⁶ cycles tested in SBF at 37°C. A fatigue limit of 110MPa at 10⁷ cycles in air was observed for extruded WE43 alloy compared to 40MPa at 10⁷ cycles tested in SBF at 37°C. 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.

  19. Microstructure formation mechanism and properties of AZ61 alloy processed by melt treatment with vibrating cooling slope and semisolid rolling

    NASA Astrophysics Data System (ADS)

    Zhao, Zhan Yong; Guan, Ren Guo; Wang, Xiang; Li, Yang; Dong, Lei; Lee, Chong Soo; Liu, Chun Ming

    2013-09-01

    A melt treatment with a vibrating cooling slope and a semisolid rolling process to produce an AZ61 alloy strip was proposed. The microstructure formation mechanism and the properties of the AZ61 alloy produced by the proposed process were investigated. Due to the high cooling rate and stirring action caused by the vibration cooling slope, the nucleation rate was greatly improved, which caused the formation of fine spherical or rosette primary grains. During the rolling process, the solid fraction increased from the entrance to the exit of the roll gap, and under the shearing action of the roller, the distribution of solute in the melt was homogenous, and the primary grains grew further. When the casting temperature was 680 °C, a strip with a cross section of 4 mm×160 mm was produced and a homogeneous microstructure was obtained. The ultimate tensile strength of the AZ61 alloy strip produced by the proposed method reached 242 MPa, and the corresponding elongation to failure was 4%, which were better than those achieved in previous similar studies.

  20. H2A.Z and H3.3 histone variants affect nucleosome structure: biochemical and biophysical studies.

    PubMed

    Thakar, Amit; Gupta, Pooja; Ishibashi, Toyotaka; Finn, Ron; Silva-Moreno, Begonia; Uchiyama, Susumu; Fukui, Kiichi; Tomschik, Miroslav; Ausio, Juan; Zlatanova, Jordanka

    2009-11-24

    Histone variants play important roles in regulation of chromatin structure and function. To understand the structural role played by histone variants H2A.Z and H3.3, both of which are implicated in transcription regulation, we conducted extensive biochemical and biophysical analysis on mononucleosomes reconstituted from either random-sequence DNA derived from native nucleosomes or a defined DNA nucleosome positioning sequence and recombinant human histones. Using established electrophoretic and sedimentation analysis methods, we compared the properties of nucleosomes containing canonical histones and histone variants H2A.Z and H3.3 (in isolation or in combination). We find only subtle differences in the compaction and stability of the particles. Interestingly, both H2A.Z and H3.3 affect nucleosome positioning, either creating new positions or altering the relative occupancy of the existing nucleosome position space. On the other hand, only H2A.Z-containing nucleosomes exhibit altered linker histone binding. These properties could be physiologically significant as nucleosome positions and linker histone binding partly determine factor binding accessibility.

  1. 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

  2. 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.

  3. The Future of American Cities.

    ERIC Educational Resources Information Center

    Gordon, Dan

    1990-01-01

    Downtown developments have saved some cities from collapse but don't make up for the loss of federal funds, nor do they provide jobs or housing suitable for most inner city residents. Nothing, however, has hurt the inner cities more than drug use. (DM)

  4. Time Dependent Magnesium AZ31B Behavior: Experimental and Physically based Modeling Investigation

    NASA Astrophysics Data System (ADS)

    Rodriguez, A. K.; Ayoub, G.; Kridli, G.; Zbib, H.

    The need to produce vehicles with improved fuel efficiency and reduced emissions has led the automotive industry to consider use of "lightweighting" materials in the construction of automotive body and chassis systems. For automotive body structures and closure panel applications, mostly made of sheet, aluminum alloys are being introduced due to their lower densities and relatively high specific strengths, as well as their compatibility with the traditional manufacturing process that are used with steel. However, interest has been increasingly focusing on the use of sheet magnesium in the manufacturing of panels and structural components, since its density is about 40% lower compared to aluminum. Accordingly, the objectives of this study are to investigate the evolution of microstructure during thermo-mechanical processing of twin-roll cast AZ31B alloys sheets, and to examine the mechanical properties of the alloy under superplastic conditions. The rate dependent crystal plasticity model have been used and integrated using an explicit model was coupled with the Taylor polycrystal model in the aim to capture the overall behavior of our studied material.

  5. In vivo response of AZ31 alloy as biliary stents: a 6 months evaluation in rabbits

    PubMed Central

    Liu, Yang; Zheng, Shengmin; Li, Nan; Guo, Huahu; Zheng, Yufeng; Peng, Jirun

    2017-01-01

    Mg-based metallic materials have been making continuing progress as vascular stents. However, the research of Mg-based materials as non-vascular stents is still at its primary stage. AZ31 stents hereby were implanted into the common bile duct of rabbits for 6 months. The results revealed an existence of 93.82 ± 1.36% and 30.89 ± 2.46% of the original volume after 1 and 3 month, respectively. Whole blood tests indicated an inflammation decreasing to normal level after 3 month implantation. A benign host response was observed via H&E staining. Nonuniform corrosion at the two ends of the stents was observed and considered the results of flow or local inflammation. Moreover, the application of Mg-based materials for different stenting treatment were reviewed and compared. Esophagus was hypothesized most destructive, whilst blood vessel and bile duct considered similar and less destructive. Trachea and nasal cavity were thought to be mildest. PMID:28084306

  6. Failure analysis of AZ31 magnesium alloy sheets based on the extended GTN damage model

    NASA Astrophysics Data System (ADS)

    Wang, Rui-ze; Chen, Zhang-hua; Li, Yu-jie; Dong, Chao-fang

    2013-12-01

    Based on the Gurson-Tvergaard-Needleman (GTN) model and Hill's quadratic anisotropic yield criterion, a combined experimental-numerical study on fracture initiation in the process of thermal stamping of Mg alloy AZ31 sheets was carried out. The aim is to predict the formability of thermal stamping of the Mg alloy sheets at different temperatures. The presented theoretical framework was implemented into a VUMAT subroutine for ABAQUS/EXPLICIT. Internal damage evolution due to void growth and coalescence developed at different temperatures in the Mg alloy sheets was observed by scanning electron microscopy (SEM). Moreover, the thermal effects on the void growth, coalescence, and fracture behavior of the Mg alloy sheets were analyzed by the extended GTN model and forming limit diagrams (FLD). Parameters employed in the GTN model were determined from tensile tests and numerical iterative computation. The distribution of major and minor principal strains in the specimens was determined from the numerical results. Therefore, the corresponding forming limit diagrams at different stress levels and temperatures were drawn. The comparison between the predicted forming limits and the experimental data shows a good agreement.

  7. Interfacial chemistry of organic conversion film on AZ61 magnesium alloy surface

    NASA Astrophysics Data System (ADS)

    Yang, Xu; Pan, Fusheng; Zhang, Dingfei

    2008-12-01

    The anodic electrochemical behavior of AZ61 magnesium alloy in sodium hydroxide medium in the absence and presence of p-nitro-benzene-azo-resorcinol (PNBAR) was studied using electrochemical techniques. In the presence of PNBAR, organic conversion film formed on the surface of magnesium alloy. The nature of chemical mechanisms, bonds, and structures at the interface of PNBAR/magnesium alloy was investigated by using energy dispersive spectrometer (EDS) analysis and Fourier transform infrared spectroscopy. An in situ electrochemical deposition was evidenced to produce a corrosion protective barrier by the formation of organic conversion film of magnesium-PNBAR complex and to enhance film adhesion by the covalent bonds of Mg sbnd O sbnd N linkage. The linear sweep voltammetry experiments and the score tests were used to investigate the adhesion and evaluate the potential of corrosion resistance of organic conversion film. The results indicated the corrosion resistance of magnesium alloy was improved, the organic conversion film showed excellent adhesion not only to the substrate but also to the outer paint coatings.

  8. Rate sensitivity and tension–compression asymmetry in AZ31B magnesium alloy sheet

    PubMed Central

    Kurukuri, Srihari; Worswick, Michael J.; Ghaffari Tari, Dariush; Mishra, Raja K.; Carter, Jon T.

    2014-01-01

    The constitutive response of a commercial magnesium alloy rolled sheet (AZ31B-O) is studied based on room temperature tensile and compressive tests at strain rates ranging from 10−3 to 103 s−1. Because of its strong basal texture, this alloy exhibits a significant tension–compression asymmetry (strength differential) that is manifest further in terms of rather different strain rate sensitivity under tensile versus compressive loading. Under tensile loading, this alloy exhibits conventional positive strain rate sensitivity. Under compressive loading, the flow stress is initially rate insensitive until twinning is exhausted after which slip processes are activated, and conventional rate sensitivity is recovered. The material exhibits rather mild in-plane anisotropy in terms of strength, but strong transverse anisotropy (r-value), and a high degree of variation in the measured r-values along the different sheet orientations which is indicative of a higher degree of anisotropy than that observed based solely upon the variation in stresses. This rather complex behaviour is attributed to the strong basal texture, and the different deformation mechanisms being activated as the orientation and sign of applied loading are varied. A new constitutive equation is proposed to model the measured compressive behaviour that captures the rate sensitivity of the sigmoidal stress–strain response. The measured tensile stress–strain response is fit to the Zerilli–Armstrong hcp material model. PMID:24711496

  9. Characterizing Sky Brightness Variations 2014: Fort Collins, CO and Tucson, AZ

    NASA Astrophysics Data System (ADS)

    Culver, Roger B.; Craine, Erin M.; Wall, Renae E.

    2015-05-01

    Internet enabled sky brightness meters (iSBM), designed and manufactured by STEM Laboratory, Inc., have been operated and tested at several locations for the last few years. The iSBM units are zenith looking, single channel, broadband photometers that record sky brightness continuously at a cadence of about 40-sec. They operate every night regardless of weather, thus providing a record of sky brightness useful not only for astronomers (clear nights), but also wildlife biologists who are concerned with the real range of local sky brightness. Data logged include time, date, geographic location, elevation, sky brightness, twilight times, moonrise/set times, lunar phase, cloud cover, temperature, humidity, barometric pressure, and dew-point. We have examined recent archives of iSBM data for two different types of locations: Fort Collins, CO and Tucson, AZ. From the archives we have calculated statistics of sky brightness and compare the results to provide a qualitative and quantitative description of natural ranges of sky brightness trends.

  10. Microstructure Evolution during Roller Hemming of AZ31B Magnesium Sheet

    NASA Astrophysics Data System (ADS)

    Levinson, Amanda; Mishra, Raja K.; Doherty, Roger D.; Kalidindi, Surya R.

    2012-10-01

    The differences in the microstructure evolution during laser-roller hemming and conventional roller hemming (done at room temperature) of commercial-grade AZ31B sheet were studied using electron backscatter diffraction (EBSD). It was observed that the flanging operation, done as a precursor to roller hemming, produced a heterogeneous grain structure that remained throughout the subsequent hemming steps. Laser heating, applied during the roller passes, significantly reduced the amount of both extension and contraction twinning in the inner and outer band, respectively. More importantly, after two roller passes without laser heating, extension twinning in the inner band seemed to saturate. This forced the material in the inner band to accommodate further deformation by harder mechanisms, such as pyramidal slip and contraction twinning, during the third roller pass when failure occurred. The laser-hemmed samples exhibited much lower hardness values, especially in the inner band, which was deemed to be largely responsible for the success of the hemming operation with laser heating.

  11. High current pulsed electron beam treatment of AZ31 Mg alloy

    SciTech Connect

    Gao Bo; Hao Shengzhi; Zou Jianxin; Grosdidier, Thierry; Jiang Limin; Zhou Jiyang; Dong Chuang

    2005-11-15

    This paper reports, for the first time, an analysis of the effect of High Current Pulsed Electron Beam (HCPEB) on a Mg alloy. The AZ31 alloy was HCPEB treated in order to see the potential of this fairly recent technique in modifying its wear resistance. For the 2.5 J/cm{sup 2} beam energy density used in the present work, the evaporation mode was operative and led to the formation of a ''wavy'' surface and the absence of eruptive microcraters. The selective evaporation of Mg over Al led to an Al-rich melted surface layer and precipitation hardening from the over saturated solid solution. Due to the increase in hardness of the top surface layer, the friction coefficient values were lowered by more than 20% after the HCPEB treatments, and the wear resistance was drastically (by a factor of 6) improved. The microhardness of the HCPEB samples was also increased significantly down to a depth of about 500 {mu}m, far exceeding the heat-affected zone (about 40 {mu}m). This is due to the effect of the propagation of the shockwave associated with this HCPEB treatment.

  12. The characterization of haboobs and the deposition of dust in Tempe, AZ from 2005 to 2014

    NASA Astrophysics Data System (ADS)

    Eagar, Jershon Dale; Herckes, Pierre; Hartnett, Hilairy Ellen

    2017-02-01

    Dust storms known as 'haboobs' occur in Tempe, AZ during the North American monsoon season. This work presents a catalog of haboob occurrence over the time period 2005-2014. A classification method based on meteorological and air quality measurements is described. The major factors that distinguish haboobs events from other dust events and from background conditions are event minimum visibility, maximum wind or gust speed, and maximum PM10 (particulate matter with aerodynamic diameters of 10 μm or less) concentration. We identified from 3 to 20 haboob events per year over the period from 2005 to 2014. The calculated annual TSP (total suspended particulate) dry deposition ranged from a low of 259 kg ha-1 in 2010 to a high of 2950 kg ha-1 in 2011 with a mean of 950 kg ha-1 yr-1. The deposition of large particles (PM>10) is greater than the deposition of PM10. The TSP dry deposition during haboobs is estimated to contribute 74% of the total particulate mass deposited in Tempe.

  13. Microstructure and mechanical properties of AZ91 magnesium alloy subject to deep cryogenic treatments

    NASA Astrophysics Data System (ADS)

    Li, Gui-rong; Wang, Hong-ming; Cai, Yun; Zhao, Yu-tao; Wang, Jun-jie; Gill, Simon P. A.

    2013-09-01

    AZ91 magnesium alloy was subjected to a deep cryogenic treatment. X-ray diffraction (XRD), scanning electronic microscopy (SEM), and transmission electronic microscopy (TEM) methods were utilized to characterize the composition and microstructure of the treated samples. The results show that after two cryogenic treatments, the quantity of the precipitate hardening β phase increases, and the sizes of the precipitates are refined from 8-10 μm to 2-4 μm. This is expected to be due to the decreased solubility of aluminum in the matrix at low temperature and the significant plastic deformation owing to internal differences in thermal contraction between phases and grains. The polycrystalline matrix is also noticeably refined, with the sizes of the subsequent nanocrystalline grains in the range of 50-100 nm. High density dislocations are observed to pile up at the grain boundaries, inducing the dynamic recrystallization of the microstructure, leading to the generation of a nanocrystalline grain structure. After two deep cryogenic treatments, the tensile strength and elongation are found to be substantially increased, rising from 243 MPa and 4.4% of as-cast state to 299 MPa and 5.1%.

  14. Effects of Zr Additions on the Microstructure and Impression Creep Behavior of AZ91 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Kabirian, F.; Mahmudi, R.

    2010-12-01

    The effects of 0.2, 0.6, and 1.0 wt pct Zr additions on the microstructure and creep behavior of AZ91 Mg alloy were investigated by impression tests carried out under constant punching stress ( σ imp) in the range 100 to 650 MPa, corresponding to the modulus-compensated stress levels of {{0.007 le σ_{{imp}} } {G le 0.044}} , at temperatures in the range 425 K to 570 K (152 °C to 297 °C). The alloy containing 0.6 wt pct Zr showed the best creep resistance mainly due to the favorable formation of Al3Zr2 and Al2Zr intermetallic compounds, reduction in the volume fraction of the eutectic β-Mg17Al12 phase, and solid solution hardening effects of Al in the Mg matrix. Based on the obtained stress exponents of 4.2 to 6.5 and activation energies of 90.7 to 127.1 kJ/mol, it is proposed that two parallel mechanisms of lattice and pipe-diffusion-controlled dislocation climb compete. Dislocation climb controlled by dislocation pipe diffusion prevails at high stresses, whereas climb of edge dislocations is the controlling mechanism at low stresses.

  15. Creep behavior of an AZ91 magnesium alloy reinforced with alumina fibers

    NASA Astrophysics Data System (ADS)

    Li, Yong; Langdon, Terence G.

    1999-08-01

    Creep tests were conducted at elevated temperatures on an AZ91 alloy reinforced with 20 vol pct Al2O3 fibers. When the creep data are interpreted by incorporating a threshold stress into the analysis, it is shown that the true stress exponent, n, is ˜3 at the lower stress levels and increases to >3 at the higher stresses. The true activation energy for creep is close to the value anticipated for interdiffusion of aluminum in magnesium. This behavior is interpreted in terms of a viscous glide process with n =3 and a breakaway of the dislocations from their solute atom atmospheres at the higher stress levels. The threshold stresses in this composite appear to arise from an attractive interaction between mobile dislocations in the matrix alloy and Mg17Al12 precipitates. The experimental results reveal several important similarities between the creep behavior of this magnesium-based composite and the well-documented creep properties of aluminum-based composites.

  16. Increased corrosion resistance of the AZ80 magnesium alloy by rapid solidification.

    PubMed

    Aghion, E; Jan, L; Meshi, L; Goldman, J

    2015-11-01

    Magnesium (Mg) and Mg-alloys are being considered as implantable biometals. Despite their excellent biocompatibility and good mechanical properties, their rapid corrosion is a major impediment precluding their widespread acceptance as implantable biomaterials. Here, we investigate the potential for rapid solidification to increase the corrosion resistance of Mg alloys. To this end, the effect of rapid solidification on the environmental and stress corrosion behavior of the AZ80 Mg alloy vs. its conventionally cast counterpart was evaluated in simulated physiological electrolytes. The microstructural characteristics were examined by optical microscopy, SEM, TEM, and X-ray diffraction analysis. The corrosion behavior was evaluated by immersion, salt spraying, and potentiodynamic polarization. Stress corrosion resistance was assessed by Slow Strain Rate Testing. The results indicate that the corrosion resistance of rapidly solidified ribbons is significantly improved relative to the conventional cast alloy due to the increased Al content dissolved in the α-Mg matrix and the correspondingly reduced presence of the β-phase (Mg17 Al12 ). Unfortunately, extrusion consolidated solidified ribbons exhibited a substantial reduction in the environmental performance and stress corrosion resistance. This was mainly attributed to the detrimental effect of the extrusion process, which enriched the iron impurities and increased the internal stresses by imposing a higher dislocation density. In terms of immersion tests, the average corrosion rate of the rapidly solidified ribbons was <0.4 mm/year compared with ∼2 mm/year for the conventionally cast alloy and 26 mm/year for the rapidly solidified extruded ribbons.

  17. In vivo response of AZ31 alloy as biliary stents: a 6 months evaluation in rabbits

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Zheng, Shengmin; Li, Nan; Guo, Huahu; Zheng, Yufeng; Peng, Jirun

    2017-01-01

    Mg-based metallic materials have been making continuing progress as vascular stents. However, the research of Mg-based materials as non-vascular stents is still at its primary stage. AZ31 stents hereby were implanted into the common bile duct of rabbits for 6 months. The results revealed an existence of 93.82 ± 1.36% and 30.89 ± 2.46% of the original volume after 1 and 3 month, respectively. Whole blood tests indicated an inflammation decreasing to normal level after 3 month implantation. A benign host response was observed via H&E staining. Nonuniform corrosion at the two ends of the stents was observed and considered the results of flow or local inflammation. Moreover, the application of Mg-based materials for different stenting treatment were reviewed and compared. Esophagus was hypothesized most destructive, whilst blood vessel and bile duct considered similar and less destructive. Trachea and nasal cavity were thought to be mildest.

  18. 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.

  19. Characterisation and modelling of defect formation in direct-chill cast AZ80 alloy

    SciTech Connect

    Mackie, D.; Robson, J.D.; Withers, P.J.; Turski, M.

    2015-06-15

    Wrought magnesium alloys for demanding structural applications require high quality defect free cast feedstock. The aim of this study was to first identify and characterise typical defects in direct chill cast magnesium–aluminium–zinc (AZ) alloy billet and then use modelling to understand the origins of these defects so they can be prevented. Defects were first located using ultrasonic inspection and were then characterised using X-ray computed tomography (XCT) and serial sectioning, establishing the presence of oxide films and intermetallic particles Al{sub 8}Mn{sub 5} in all defects. A model was developed to predict the flow patterns and growth kinetics of the intermetallic phases during casting, which influence the formation of defects. Simulation of the growth of the intermetallic particles demonstrated that precipitation from the liquid occurs in the mould. The combination of the entrained oxide films and intermetallic particles recirculates in the liquid metal and continues to grow, until large enough to settle, which is predicted to occur at the centre of the mould where the flow is the slowest. Based on these predictions, strategies to reduce the susceptibility to defect formation are suggested. - Highlights: • Casting defects in magnesium direct chill casting have been imaged and characterised in 3-dimensions. • The occurrences of co-located clusters of particles and oxide films have been characterised and explained. • A coupled model has been developed to help interpret the observed trend for defects located towards the centre of billets.

  20. Effects of CH3OH Addition on Plasma Electrolytic Oxidation of AZ31 Magnesium Alloys

    NASA Astrophysics Data System (ADS)

    He, Yongyi; Chen, Li; Yan, Zongcheng; Zhang, Yalei

    2015-09-01

    Plasma electrolytic oxidation (PEO) films on AZ31 magnesium alloys were prepared in alkaline silicate electrolytes (base electrolyte) with the addition of different volume concentrations of CH3OH, which was used to adjust the thickness of the vapor sheath. The compositions, morphologies, and thicknesses of ceramic layers formed with different CH3OH concentrations were determined via X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). Corrosion behavior of the oxide films was evaluated in 3.5 wt.% NaCl solution using potentiodynamic polarization tests. PEO coatings mainly comprised Mg, MgO, and Mg2SiO4. The addition of CH3OH in base electrolytes affected the thickness, pores diameter, and Mg2SiO4 content in the films. The films formed in the electrolyte containing 12% CH3OH exhibited the highest thickness. The coatings formed in the electrolyte containing different concentrations of CH3OH exhibited similar corrosion resistance. The energy consumption of PEO markedly decreased upon the addition of CH3OH to the electrolytes. The result is helpful for energy saving in the PEO process. supported by National Natural Science Foundation of China (No. 21376088), the Project of Production, Education and Research, Guangdong Province and Ministry of Education (Nos. 2012B09100063, 2012A090300015), and Guangzhou Science and Technology Plan Projects of China (No. 2014Y2-00042)

  1. Effect of severe plastic deformation on microstructure of squeeze-cast magnesium alloy AZ31 plate

    NASA Astrophysics Data System (ADS)

    Fong, Kai Soon; Tan, Ming Jen; Atsushi, Danno; Chua, Beng Wah; Ho, Meng Kwong

    2016-10-01

    High cost and poor room temperature formability of magnesium alloy sheet are the key factors that limit its application as a feedstock material for press forming. Production of Mg plates by squeeze casting with further processing by severe plastic deformation (SPD) is a potential method to reduce cost and improve formability. In this study, AZ31 Mg plate of dimension 96×96×4 mm was successfully produced by squeeze casting, using a novel melt transfer technique, at a forging force and speed of 180 Ton and 200 mm/sec respectively. The effect of severe plastic deformation (SPD) using groove pressing on the mechanical properties of squeeze-casted Mg plate after partial homogenization was subsequently investigated. Observation of the microstructure after two cycles of groove pressing, under decreasing temperature from 543K to 493K, shows a significant grain refinement from 39 to 4.7 µm. The Vickers hardness increased by approximately 25% from 56 to 74.1 which suggests an improvement in mechanical strength as a result of both the grain refinement and work hardening. The result shows that squeeze casting combined with groove pressing is potentially an effective method for preparation of thin magnesium alloy plate with fine-grained structure and improved mechanical properties.

  2. Synthesis of AzPhchitosan-bifenthrin-PVC to protect cables against termites.

    PubMed

    Zhang, Lingkun; Cai, Weiwei; Chen, Wu-Ya; Zhang, Li; Hu, Kaikai; Guan, Yan-Qing

    2016-03-30

    The destruction of PVC cables by termites is a continuing and long-standing problem, which can lead to power leakage and power cut. Given the environmental demerits of insecticide overuse, alternative methods of addressing this problem are a highly desirable goal. In this study, we used photo-immobilization to develop a chitosan carrier system to help bifenthrin immobilize on the surface of the PVC substrate. The immobilization was analyzed using nuclear magnetic resonance (NMR), UV absorption, reverse-phase high-performance liquid chromatography (RP-HPLC), Raman absorption spectroscopy, and thermal gravimetric analysis (TGA). The surface structure and biological activity of the embedded and immobilized bifenthrin were examined using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photon-electron spectroscopy (XPS). Its efficacy was assessed in pest experiments. The results indicate a successful embedding and immobilization of bifenthrin. Furthermore, the chemical bonding network between AzPhchitosan, bifenthrin, and PVC is stable, guaranteeing no environmental release of bifenthrin, and also providing more efficacious protection against termites. The evidence suggests that this photo-immobilization of bifenthrin-embedded chitosan on the surface of PVC substrates is a novel and environmentally friendly technique for termite control. This paper also reports a modification of chitosan with respect to its novel application in environmental protection.

  3. Texture enhancement during grain growth of magnesium alloy AZ31B

    DOE PAGES

    Bhattacharyya, Jishnu J.; Agnew, S. R.; Muralidharan, G.

    2015-01-03

    In this paper, the microstructure and texture evolution during annealing of rolled Mg alloy AZ31B, at temperatures ranging from 260 to 450°C, is characterized, and a grain growth exponent of n=5, indicating inhibition of grain growth, is observed. Broadening of the normalized grain size distributions, which indicates abnormal grain growth, was observed at all temperatures investigated. It is shown, using a Zener-type analysis for pinning of grain boundaries by particles, that impurity-based particles are responsible for grain growth inhibition and abnormal grain growth. The strong basal texture which develops during rolling of the Mg alloy, resulting in an initial peakmore » intensity in the (0002) pole figure of nine multiples of a random distribution (MRD), increases to ~15 MRD during annealing at 400 and 450°C. Furthermore, a specific texture component {0001}(1120) is observed in the orientation distribution, which increases from 10 to 23 MRD at 400°C. It is hypothesized that the anisotropic grain boundary properties (i.e. low angle boundaries have low energy and mobility) are responsible for the texture strengthening. Additionally, electron backscattered diffraction reveals the recrystallized microstructure to contain a significant number of boundaries with ~30° misorientation about the <0001> direction, and this boundary type persists throughout most annealing treatments explored.« less

  4. Texture enhancement during grain growth of magnesium alloy AZ31B

    SciTech Connect

    Bhattacharyya, Jishnu J.; Agnew, S. R.; Muralidharan, G.

    2015-01-03

    In this paper, the microstructure and texture evolution during annealing of rolled Mg alloy AZ31B, at temperatures ranging from 260 to 450°C, is characterized, and a grain growth exponent of n=5, indicating inhibition of grain growth, is observed. Broadening of the normalized grain size distributions, which indicates abnormal grain growth, was observed at all temperatures investigated. It is shown, using a Zener-type analysis for pinning of grain boundaries by particles, that impurity-based particles are responsible for grain growth inhibition and abnormal grain growth. The strong basal texture which develops during rolling of the Mg alloy, resulting in an initial peak intensity in the (0002) pole figure of nine multiples of a random distribution (MRD), increases to ~15 MRD during annealing at 400 and 450°C. Furthermore, a specific texture component {0001}(1120) is observed in the orientation distribution, which increases from 10 to 23 MRD at 400°C. It is hypothesized that the anisotropic grain boundary properties (i.e. low angle boundaries have low energy and mobility) are responsible for the texture strengthening. Additionally, electron backscattered diffraction reveals the recrystallized microstructure to contain a significant number of boundaries with ~30° misorientation about the <0001> direction, and this boundary type persists throughout most annealing treatments explored.

  5. Single-molecule tools elucidate H2A.Z nucleosome composition

    PubMed Central

    Chen, Jiji; Miller, Andrew; Kirchmaier, Ann L.; Irudayaraj, Joseph M. K.

    2012-01-01

    Summary Although distinct epigenetic marks correlate with different chromatin states, how they are integrated within single nucleosomes to generate combinatorial signals remains largely unknown. We report the successful implementation of single molecule tools constituting fluorescence correlation spectroscopy (FCS), pulse interleave excitation-based Förster resonance energy transfer (PIE-FRET) and fluorescence lifetime imaging-based FRET (FLIM-FRET) to elucidate the composition of single nucleosomes containing histone variant H2A.Z (Htz1p in yeast) in vitro and in vivo. We demonstrate that yeast nucleosomes containing Htz1p are primarily composed of H4 K12ac and H3 K4me3 but not H3 K36me3 and that these patterns are conserved in mammalian cells. Quantification of epigenetic modifications in nucleosomes will provide a new dimension to epigenetics research and lead to a better understanding of how these patterns contribute to the targeting of chromatin-binding proteins and chromatin structure during gene regulation. PMID:22393239

  6. Modification and upgrade of AzRISE/TEP solar photovoltaic test yard

    NASA Astrophysics Data System (ADS)

    Bennett, Whit; Fishgold, Asher; Lai, Teh; Elwood, Teri; Potter, Barrett G.; Simmons-Potter, Kelly

    2016-09-01

    The University of Arizona AzRISE (Arizona Research Institute for Solar Energy) and Tucson Electric Power solar test yard is currently undergoing renovations to upgrade and standardize the data acquisition capabilities throughout the yard. Test yard improvements have enabled increased data collection reliability through state-of-the-art and environmentallyrobust data logging and real-time analysis. Enhanced capabilities include 10 msec max. data resolution, precision PV backside temperature monitoring of both individual and strings of modules, measurement of both AC and DC outputs as well as GHI and POA irradiance, active data backup to eliminate data intermittency, and robust Ethernet connectivity for data collection. An on-site weather station, provides wind speed and direction, relative humidity, and air temperature data. The information collected is accessed remotely via web server and includes raw performance and environmental conditions as well as extracted figures of performance for systems under test. Complementing the UA's existing accelerated environmental-testing chamber, the new test yard acquisition capabilities have enabled high fidelity system and sub-system-level operational testing under a range of field-level test conditions. The combined facilities, thus, provide a full-spectrum testing resource for photovoltaic performance and degradation analysis. Specific measurement characteristics and sample data collected from a polysilicon module test string are utilized to illustrate test yard capabilities.

  7. 78 FR 23869 - Safety Zone; Redwood City 4th of July Fireworks Show; Port of Redwood City, Redwood City, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-23

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Redwood City 4th of July Fireworks Show; Port of Redwood City, Redwood City, CA AGENCY: Coast Guard, DHS. ACTION: Notice of proposed rulemaking... of Redwood City near Redwood City, CA in support of the Redwood City 4th of July Fireworks Show...

  8. Mussel-inspired functionalization of PEO/PCL composite coating on a biodegradable AZ31 magnesium alloy.

    PubMed

    Tian, Peng; Xu, Demin; Liu, Xuanyong

    2016-05-01

    The rapid degradation of magnesium-based implants in physiological environments in vivo not only will quickly deteriorate their mechanical strengths but will also lead to a severe change of the micro-environment around the implants, which may cause the final failure of magnesium-based implants. In this work, a polycaprolactone (PCL) layer was prepared to seal the plasma electrolytic oxidization coating (PEO) to form a PEO/PCL composite coating on a biodegradable AZ31 magnesium alloy, followed by further surface functionalization with polydopamine. The in vitro degradation behaviors of the bare AZ31 alloy and coated samples were evaluated in a simulated body fluid (SBF) using the potentiodynamic polarization curve test and the static immersion test. The bioactivity of the samples was investigated using the SBF soaking test. The cytocompatibility of all samples was evaluated using the cytotoxicity test and analysis of the adhesion and proliferation of osteoblast cells (MC3T3-E1) directly cultivated on the sample surface. The results showed that the PCL layer successfully sealed the pores of the PEO coating, and then the polydopamine layer formed on its surface. The in vitro degradation tests showed that the PEO/PCL composite coating improved the corrosion resistance of the AZ31 alloy in SBF with a more positive corrosion potential and a lower corrosion current density. Due to the protection of the PEO/PCL composite coating, the surrounding environment showed nearly no influence on the degradation of the coated sample, which led to no obvious local alkalization and hydrogen evolution. Moreover, compared with the AZ31 alloy and PEO coating, the PEO/PCL composite coating was more suitable for cell adhesion and proliferation. After further surface functionalization by polydopamine, the corrosion resistance of the composite coating was maintained, while its bioactivity was significantly enhanced with a large amount of hydroxyapatite (HA) formed on its surface after

  9. Martian City Map

    NASA Technical Reports Server (NTRS)

    2004-01-01

    30 May 2004 Seasonal frost can enhance the view from orbit of polar polygonal patterns on the surface of Mars. Sometimes these patterns look something like a city map, or the view from above a city lit-up at night. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from the south polar region near 80.7oS, 70.6oW. Polar polygons on Mars are generally believed, though not proven, to be the result of freeze/thaw cycles of ice occurring within the upper few meters (several yards) of the martian subsurface. The image shown here covers an area about 3 km (1.9 mi) across; sunlight illuminates the scene from the upper left.

  10. [Itinerant physicians, the art of healing and doctors in national history (Mexico City, 1877-1911)].

    PubMed

    Agostoni, Claudia

    2008-01-01

    The uncertainty and mistrust towards the presence and activities of academic medical practitioners in Mexico City during the Porfirio Díaz government (1877-1911) convinced these professionals that is was essential to create, strengthen and transmit a respectable, competent and homogeneous image of the profession. To this purpose they recovered, recreated and adapted the ethical maxims of the occidental medical culture to their professional work, and rescued eminent medical figures of Mexico's convulse nineteenth century from being lost in the oblivion of history. Their goal - as it will be expounded in the following pages - was to respond, oppose and neutralize the criticism and disbelief expressed by the public against their professional performance.

  11. Garden City, Kansas

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Center pivot irrigation systems create red circles of healthy vegetation in this image of croplands near Garden City, Kansas. This image was acquired by Landsat 7's Enhanced Thematic Mapper plus (ETM+) sensor on September 25, 2000. This is a false-color composite image made using near infrared, red, and green wavelengths. The image has also been sharpened using the sensor's panchromatic band. Image provided by the USGS EROS Data Center Satellite Systems Branch

  12. SWR1 Chromatin-Remodeling Complex Subunits and H2A.Z Have Non-overlapping Functions in Immunity and Gene Regulation in Arabidopsis.

    PubMed

    Berriri, Souha; Gangappa, Sreeramaiah N; Kumar, S Vinod

    2016-07-06

    Incorporation of the histone variant H2A.Z into nucleosomes by the SWR1 chromatin remodeling complex is a critical step in eukaryotic gene regulation. In Arabidopsis, SWR1c and H2A.Z have been shown to control gene expression underlying development and environmental responses. Although they have been implicated in defense, the specific roles of the complex subunits and H2A.Z in immunity are not well understood. In this study, we analyzed the roles of the SWR1c subunits, PHOTOPERIOD-INDEPENDENT EARLY FLOWERING1 (PIE1), ACTIN-RELATED PROTEIN6 (ARP6), and SWR1 COMPLEX 6 (SWC6), as well as H2A.Z, in defense and gene regulation. We found that SWR1c components play different roles in resistance to different pathogens. Loss of PIE1 and SWC6 function as well as depletion of H2A.Z led to reduced basal resistance, while loss of ARP6 fucntion resulted in enhanced resistance. We found that mutations in PIE1 and SWC6 resulted in impaired effector-triggered immunity. Mutation in SWR1c components and H2A.Z also resulted in compromised jasmonic acid/ethylene-mediated immunity. Genome-wide expression analyses similarly reveal distinct roles for H2A.Z and SWR1c components in gene regulation, and suggest a potential role for PIE1 in the regulation of the cross talk between defense signaling pathways. Our data show that although they are part of the same complex, Arabidopsis SWR1c components could have non-redundant functions in plant immunity and gene regulation.

  13. Loss of mechanical properties in vivo and bone-implant interface strength of AZ31B magnesium alloy screws with Si-containing coating.

    PubMed

    Tan, Lili; Wang, Qiang; Lin, Xiao; Wan, Peng; Zhang, Guangdao; Zhang, Qiang; Yang, Ke

    2014-05-01

    In this study the loss of mechanical properties and the interface strength of coated AZ31B magnesium alloy (a magnesium-aluminum alloy) screws with surrounding host tissues were investigated and compared with non-coated AZ31B, degradable polymer and biostable titanium alloy screws in a rabbit animal model after 1, 4, 12 and 21weeks of implantation. The interface strength was evaluated in terms of the extraction torque required to back out the screws. The loss of mechanical properties over time was indicated by one-point bending load loss of the screws after these were extracted at different times. AZ31B samples with a silicon-containing coating had a decreased degradation rate and improved biological properties. The extraction torque of Ti6Al4V, poly-l-lactide (PLLA) and coated AZ31B increased significantly from 1week to 4weeks post-implantation, indicating a rapid osteosynthesis process over 3weeks. The extraction torque of coated AZ31B increased with implantation time, and was higher than that of PLLA after 4weeks of implantation, equalling that of Ti6Al4V at 12weeks and was higher at 21weeks. The bending loads of non-coated AZ31B and PLLA screws degraded sharply after implantation, and that of coated AZ31B degraded more slowly. The biodegradation mechanism, the coating to control the degradation rate and the bioactivity of magnesium alloys influencing the mechanical properties loss over time and bone-implant interface strength are discussed in this study and it is concluded that a suitable degradation rate will result in an improvement in the mechanical performance of magnesium alloys, making them more suitable for clinical application.

  14. Human diffusion and city influence

    PubMed Central

    Lenormand, Maxime; Gonçalves, Bruno; Tugores, Antònia; Ramasco, José J.

    2015-01-01

    Cities are characterized by concentrating population, economic activity and services. However, not all cities are equal and a natural hierarchy at local, regional or global scales spontaneously emerges. In this work, we introduce a method to quantify city influence using geolocated tweets to characterize human mobility. Rome and Paris appear consistently as the cities attracting most diverse visitors. The ratio between locals and non-local visitors turns out to be fundamental for a city to truly be global. Focusing only on urban residents' mobility flows, a city-to-city network can be constructed. This network allows us to analyse centrality measures at different scales. New York and London play a central role on the global scale, while urban rankings suffer substantial changes if the focus is set at a regional level. PMID:26179991

  15. Is a healthy city also an age-friendly city?

    PubMed

    Jackisch, Josephine; Zamaro, Gianna; Green, Geoff; Huber, Manfred

    2015-06-01

    Healthy Ageing is an important focus of the European Healthy Cities Network and has been supported by WHO since 2003 as a key strategic topic, since 2010 in cooperation with the Global Network of Age-friendly Cities and Communities. Based on the methodology of realist evaluation, this article synthesizes qualitative evidence from 33 structured case studies (CS) from 32 WHO European Healthy Cities, 72 annual reports from Network cities and 71 quantitative responses to a General Evaluation Questionnaire. City cases are assigned to three clusters containing the eight domains of an age-friendly city proposed by WHO's Global Age-friendly City Guide published in 2007. The analysis of city's practice and efforts in this article takes stock of how cities have developed the institutional prerequisites and processes necessary for implementing age-friendly strategies, programmes and projects. A content analysis of the CS maps activities across age-friendly domains and illustrates how cities contribute to improving the social and physical environments of older people and enhance the health and social services provided by municipalities and their partners.

  16. Iron Phosphate Glass for Vitrifying Hanford AZ102 LAW in Joule Heated and Cold Crucible Induction Melters - 12240

    SciTech Connect

    Day, Delbert E.; Brow, Richard K.; Ray, Chandra S.; Reis, Signo T.; Kim, Cheol-Woon; Vienna, John D.; Sevigny, Gary; Peeler, David; Johnson, Fabienne C.; Hansen, Eric K.; Soelberg, Nick; Pegg, Ian L.; Gan, Hao

    2012-07-01

    An iron phosphate composition for vitrifying a high sulfate (∼17 wt%) and high alkali (∼80 wt%) Hanford low activity waste (LAW), known as AZ-102 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 AZ-102 which corresponded to a total alkali and sulfate (represented as SO{sub 3}) content of 21 and 4.4 wt%, respectively. A slurry (7 M Na{sup +}) of MS26AZ102F-2 simulant was melted continuously at temperatures between 1030 and 1090 deg. C for 10 days in a small JHM at PNNL and for 70 hours in a CCIM at INL. The as-cast glasses produced in both melters and in trial laboratory experiments along with their canister centerline cooled (CCC) counterparts met the requirements for the Product Consistency Test (PCT) and the Vapor Hydration Test (VHT) responses in the Hanford Tank Waste Treatment and Immobilization Plant (WTP) Contract. These glass waste forms retained up to 77 % of the SO{sub 3} (3.3 wt%), 100% of the Cesium, and 33 to 44% of the rhenium (used as a surrogate for Tc) 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 was melted continuously in a slurry fed JHM and in the US, thereby, demonstrating that iron phosphate glasses can be used as alternative hosts for vitrifying nuclear waste. The following conclusions are drawn from the results of the present work. (1) An iron phosphate composition, designated as MS26AZ102F-2, containing 26 wt% of the simulated high sulfate (17 wt%), high alkali (80 wt%) Hanford AZ-102 LAW meets all the criteria for processing in a JHM and CCIM. This

  17. Mechanical Behavior and Microstructural Analysis of Extruded AZ31B Magnesium Alloy Processed by Backward Extrusion

    NASA Astrophysics Data System (ADS)

    Zhou, Ping; Beeh, Elmar; Friedrich, Horst E.; Grünheid, Thomas

    2016-07-01

    This study investigates the mechanical behavior of an extruded AZ31B magnesium alloy profile at various strain rates from 0.001 to 375/s. The electron backscatter diffraction analysis revealed that the profile has \\{ { 0 0 0 1} \\}< 1 0overline{1} 0 rangle and \\{ {1 0overline{1} 0 }\\}< { 1 1overline{2} 0}rangle textures. Due to the textures, the profile exhibits pronounced anisotropy in mechanical properties. In the extrusion direction (ED), the profile shows the highest yield strength (YS) but the lowest total elongation at fracture (TE) due to a hard activation of non-basal slip and \\{ { 1 0overline{1} 1} \\}< { 1 0overline{1} overline{2} } rangle twinning; in the diagonal direction (DD), it shows the lowest ultimate tensile strength (UTS) but the highest TE due to an easy activation of basal slip; in the transverse direction (TD), it shows the lowest YS due to an easy activation of \\{ {10overline{1} 2} \\}< {10overline{1} overline{1} } rangle twinning. Moreover, the number of twins increases with the increasing strain rate. This indicates that deformation twinning becomes prevalent to accommodate high-rate deformation. Due to the different deformation mechanisms, the profile exhibits an orientation-dependent effect of strain rate on the mechanical properties. A positive effect of strain rate on the YS and UTS was found in the ED, while the effect of strain rate on the YS is negligible in the DD and TD. The TE in the ED, DD, and TD decreases in general as the strain rate increases. Fractographic analysis under a scanning electron microscope revealed that the fracture is a mixed mode of ductile and brittle fracture, and the magnesium oxide inclusions could be the origins of the fracture.

  18. Plastic Deformation Characteristics Of AZ31 Magnesium Alloy Sheets At Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Park, Jingee; Lee, Jongshin; You, Bongsun; Choi, Seogou; Kim, Youngsuk

    2007-05-01

    Using lightweight materials is the emerging need in order to reduce the vehicle's energy consumption and pollutant emissions. Being a lightweight material, magnesium alloys are increasingly employed in the fabrication of automotive and electronic parts. Presently, magnesium alloys used in automotive and electronic parts are mainly processed by die casting. The die casting technology allows the manufacturing of parts with complex geometry. However, the mechanical properties of these parts often do not meet the requirements concerning the mechanical properties (e.g. endurance strength and ductility). A promising alternative can be forming process. The parts manufactured by forming could have fine-grained structure without porosity and improved mechanical properties such as endurance strength and ductility. Because magnesium alloy has low formability resulted form its small slip system at room temperature it is usually formed at elevated temperature. Due to a rapid increase of usage of magnesium sheets in automotive and electronic industry it is necessary to assure database for sheet metal formability and plastic yielding properties in order to optimize its usage. Especially, plastic yielding criterion is a critical property to predict plastic deformation of sheet metal parts in optimizing process using CAE simulation. Von-Mises yield criterion generally well predicts plastic deformation of steel sheets and Hill'1979 yield criterion predicts plastic deformation of aluminum sheets. In this study, using biaxial tensile test machine yield loci of AZ31 magnesium alloy sheet were obtained at elevated temperature. The yield loci ensured experimentally were compared with the theoretical predictions based on the Von-Mises, Hill, Logan-Hosford, and Barlat model.

  19. Source apportionment of fine particulate matter in Phoenix, AZ, using positive matrix factorization

    SciTech Connect

    Steven G. Brown; Anna Frankel; Sean M. Raffuse; Paul T. Roberts; Hilary R. Hafner; Darcy J. Anderson

    2007-06-15

    Speciated particulate matter PM2.5 data collected as Part. of the Interagency Monitoring of Protected Visual Environments (IMPROVE) program in Phoenix, AZ, from April 2001 through October 2003 were analyzed using the multivariate receptor model, positive matrix factorization (PMF). Over 250 samples and 24 species were used, including the organic carbon and elemental carbon analytical temperature fractions from the thermal optical reflectance method. A two-step approach was used. First, the species excluding the carbon fractions were used, and initially eight factors were identified; non-soil potassium was calculated and included to better refine the burning factor. Next, the mass associated with the burning factor was removed, and the data set rerun with the carbon fractions. Results were very similar (i.e., within a few percent), but this step enabled a separation of the mobile factor into gasoline and diesel vehicle emissions. The identified factors were burning (on average 2% of the mass), secondary transport (7%), regional power generation (13%), dust (25%), nitrate (9%), industrial As/Pb/Se (2%), Cu/Ni/V (7%), diesel (9%), and general mobile (26%). Most of the long-range transport of emissions emanates from south of Phoenix in Southeastern Arizona, West Texas, and Mexico, which are significant source regions of SO{sub 2} emissions from coal- and oil-fired power plants. The overall contribution from mobile sources also increased, as some mass (OC and nitrate) from the nitrate and regional power generation factors were apportioned with the mobile factors. This approach allowed better apportionment of carbon as well as total mass. Additionally, the use of multiple supporting analyses, including air mass trajectories, activity trends, and emission inventory information, helped increase confidence in factor identification. 86 refs., 10 figs., 2 tabs.

  20. The Origin of Fracture in the I-ECAP of AZ31B Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Gzyl, Michal; Rosochowski, Andrzej; Boczkal, Sonia; Qarni, Muhammad Jawad

    2015-11-01

    Magnesium alloys are very promising materials for weight-saving structural applications due to their low density, comparing to other metals and alloys currently used. However, they usually suffer from a limited formability at room temperature and low strength. In order to overcome those issues, processes of severe plastic deformation (SPD) can be utilized to improve mechanical properties, but processing parameters need to be selected with care to avoid fracture, very often observed for those alloys during forming. In the current work, the AZ31B magnesium alloy was subjected to SPD by incremental equal-channel angular pressing (I-ECAP) at temperatures varying from 398 K to 525 K (125 °C to 250 °C) to determine the window of allowable processing parameters. The effects of initial grain size and billet rotation scheme on the occurrence of fracture during I-ECAP were investigated. The initial grain size ranged from 1.5 to 40 µm and the I-ECAP routes tested were A, BC, and C. Microstructures of the processed billets were characterized before and after I-ECAP. It was found that a fine-grained and homogenous microstructure was required to avoid fracture at low temperatures. Strain localization arising from a stress relaxation within recrystallized regions, namely twins and fine-grained zones, was shown to be responsible for the generation of microcracks. Based on the I-ECAP experiments and available literature data for ECAP, a power law between the initial grain size and processing conditions, described by a Zener-Hollomon parameter, has been proposed. Finally, processing by various routes at 473 K (200 °C) revealed that route A was less prone to fracture than routes BC and C.

  1. Large cities are less green.

    PubMed

    Oliveira, Erneson A; Andrade, José S; Makse, Hernán A

    2014-02-28

    We study how urban quality evolves as a result of carbon dioxide emissions as urban agglomerations grow. We employ a bottom-up approach combining two unprecedented microscopic data on population and carbon dioxide emissions in the continental US. We first aggregate settlements that are close to each other into cities using the City Clustering Algorithm (CCA) defining cities beyond the administrative boundaries. Then, we use data on CO2 emissions at a fine geographic scale to determine the total emissions of each city. We find a superlinear scaling behavior, expressed by a power-law, between CO2 emissions and city population with average allometric exponent β = 1.46 across all cities in the US. This result suggests that the high productivity of large cities is done at the expense of a proportionally larger amount of emissions compared to small cities. Furthermore, our results are substantially different from those obtained by the standard administrative definition of cities, i.e. Metropolitan Statistical Area (MSA). Specifically, MSAs display isometric scaling emissions and we argue that this discrepancy is due to the overestimation of MSA areas. The results suggest that allometric studies based on administrative boundaries to define cities may suffer from endogeneity bias.

  2. Large cities are less green

    NASA Astrophysics Data System (ADS)

    Oliveira, Erneson A.; Andrade, José S.; Makse, Hernán A.

    2014-02-01

    We study how urban quality evolves as a result of carbon dioxide emissions as urban agglomerations grow. We employ a bottom-up approach combining two unprecedented microscopic data on population and carbon dioxide emissions in the continental US. We first aggregate settlements that are close to each other into cities using the City Clustering Algorithm (CCA) defining cities beyond the administrative boundaries. Then, we use data on CO2 emissions at a fine geographic scale to determine the total emissions of each city. We find a superlinear scaling behavior, expressed by a power-law, between CO2 emissions and city population with average allometric exponent β = 1.46 across all cities in the US. This result suggests that the high productivity of large cities is done at the expense of a proportionally larger amount of emissions compared to small cities. Furthermore, our results are substantially different from those obtained by the standard administrative definition of cities, i.e. Metropolitan Statistical Area (MSA). Specifically, MSAs display isometric scaling emissions and we argue that this discrepancy is due to the overestimation of MSA areas. The results suggest that allometric studies based on administrative boundaries to define cities may suffer from endogeneity bias.

  3. Securing water for the cities.

    PubMed

    Satterthwaite, D

    1993-01-01

    Many cities in developing countries have grown so much that they can no longer provide adequate, sustainable water. Over pumping in Dakar and Mexico City has forced those cities to obtain water from ever more distant sources. In Dakar, the result has been saltwater intrusion. Overpumping has caused Mexico City to sink, in some areas by as much as 9 m, resulting in serious damage to buildings and sewage and drainage pipes. Other cities facing similar water problems are coastal cities in Peru (e.g., Lima), La Rioja and Catamarca in Argentina, cities in Northern Mexico, and cities in dry areas of Africa. For some cities, the problem is not so much ever more distant water supplies but insufficient funds to expand supplies. Bangkok and Jakarta both face saltwater intrusion into their overdrawn aquifers. Even through agriculture is the dominant user of water in most countries, demand concentrated in a small area exhausts local and regional sources and pollutes rivers, lakes, and coasts with untreated human and industrial waste. Most cities in Africa and Asia do not have a sewerage system. Further, most cities do not have the drains to deal with storm water and external floodwater, causing frequent, seasonal flooding. The resulting stagnant water provides breeding grounds for insect vectors of diseases (e.g., malaria). The problems in most cities are a result of poor management, not lack of water. Reducing leaks in existing piped distribution systems from the usual 60% loss of water to leaks to 12% would increase the available water 2-fold. Another way to address water shortages would be commercial, industrial, and recreational use of minimally treated waste water, such as is the case in Madras and Mexico City. Political solutions are needed to resolve inadequate water supply and waste management.

  4. Effects of the pouring temperature on the formation of the bonding zone between AZ91 and AlSi17 in the compound casting process

    NASA Astrophysics Data System (ADS)

    Mola, R.; Bucki, T.; Dziadoń, A.

    2017-02-01

    The compound casting process was used to join AZ91 magnesium alloy to AlSi17 aluminium alloy. Liquid AZ91 was poured onto a solid AlSi17 insert placed in a steel mould heated to 370 °C. The experimental results showed that the temperature of the AZ91 melt affected the formation of the bonding zone between the two alloys. A continuous bonding zone was formed by applying a pouring temperature of 650 °C. The use of higher temperatures, i.e. 680 °C and 700 °C, did not lead to the formation of a continuous metallurgical transition zone at the AZ91/AlSi17 interface. The bonding zone was analysed using an optical microscope and a scanning electron microscope equipped with an energy dispersive X-ray (EDS) detector. The structural constituents of the bonding zone near the AlSi17 alloy were: an Al3Mg2 intermetallic phase, primary Si particles surrounded by a rim of an Mg2Si intermetallic phase and fine Mg2Si particles. The area of the bonding zone that was adjacent to the AZ91 alloy had a eutectic structure composed of an Mg17Al12 intermetallic phase and a solid solution of Al and Si in Mg.

  5. Sequence of cDNAs for mammalian H2A.Z, an evolutionarily diverged but highly conserved basal histone H2A isoprotein species.

    PubMed Central

    Hatch, C L; Bonner, W M

    1988-01-01

    The nucleotide sequences of cDNAs for the evolutionarily diverged but highly conserved basal H2A isoprotein, H2A.Z, have been determined for the rat, cow, and human. As a basal histone, H2A.Z is synthesized throughout the cell cycle at a constant rate, unlinked to DNA replication, and at a much lower rate in quiescent cells. Each of the cDNA isolates encodes the entire H2A.Z polypeptide. The human isolate is about 1.0 kilobases long. It contains a coding region of 387 nucleotides flanked by 106 nucleotides of 5'UTR and 376 nucleotides of 3'UTR, which contains a polyadenylation signal followed by a poly A tail. The bovine and rat cDNAs have 97 and 94% nucleotide positional identity to the human cDNA in the coding region and 98% in the proximal 376 nucleotides of the 3'UTR which includes the polyadenylation signal. A potential stem-forming sequence imbedded in a direct repeat is found centered at 261 nucleotides into the 3'UTR. Each of the cDNA clones could be transcribed and translated in vitro to yield H2A.Z protein. The mammalian H2A.Z cDNA coding sequences are approximately 80% similar to those in chicken and 75% to those in sea urchin. PMID:3344202

  6. CityGML - Interoperable semantic 3D city models

    NASA Astrophysics Data System (ADS)

    Gröger, Gerhard; Plümer, Lutz

    2012-07-01

    CityGML is the international standard of the Open Geospatial Consortium (OGC) for the representation and exchange of 3D city models. It defines the three-dimensional geometry, topology, semantics and appearance of the most relevant topographic objects in urban or regional contexts. These definitions are provided in different, well-defined Levels-of-Detail (multiresolution model). The focus of CityGML is on the semantical aspects of 3D city models, its structures, taxonomies and aggregations, allowing users to employ virtual 3D city models for advanced analysis and visualization tasks in a variety of application domains such as urban planning, indoor/outdoor pedestrian navigation, environmental simulations, cultural heritage, or facility management. This is in contrast to purely geometrical/graphical models such as KML, VRML, or X3D, which do not provide sufficient semantics. CityGML is based on the Geography Markup Language (GML), which provides a standardized geometry model. Due to this model and its well-defined semantics and structures, CityGML facilitates interoperable data exchange in the context of geo web services and spatial data infrastructures. Since its standardization in 2008, CityGML has become used on a worldwide scale: tools from notable companies in the geospatial field provide CityGML interfaces. Many applications and projects use this standard. CityGML is also having a strong impact on science: numerous approaches use CityGML, particularly its semantics, for disaster management, emergency responses, or energy-related applications as well as for visualizations, or they contribute to CityGML, improving its consistency and validity, or use CityGML, particularly its different Levels-of-Detail, as a source or target for generalizations. This paper gives an overview of CityGML, its underlying concepts, its Levels-of-Detail, how to extend it, its applications, its likely future development, and the role it plays in scientific research. Furthermore, its

  7. Controlling the degradation rate of AZ91 magnesium alloy via sol-gel derived nanostructured hydroxyapatite coating.

    PubMed

    Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

    2013-10-01

    Magnesium (Mg) alloys have been introduced as new generation of biodegradable orthopedic materials in recent years since it has been proved that Mg is one of the main minerals required for osseous tissue revival. The main goal of the present study was to establish a desired harmony between the necessities of orthopedic patient body to Mg(2+) ions and degradation rate of the Mg based implants as a new class of biodegradable/bioresorbable materials. This prospect was followed by providing a sol-gel derived nanostructured hydroxyapatite (n-HAp) coating on AZ91 alloy using dip coating technique. Phase structural analysis, morphology study, microstructure characterization, and functional group identification were performed using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The prepared samples were immersed in simulated body fluid in order to study the formation of apatite-like precipitations, barricade properties of the n-HAp coating, and to estimate the dosage of released Mg(2+) ions within a specified and limited time of implantation. Electrochemical polarization tests were carried out to evaluate and compare the corrosion behavior of the n-HAp coated and uncoated samples. The changes of the in vitro pH values were also evaluated. Results posed the noticeable capability of n-HAp coating on stabilizing alkalization behavior and improving the corrosion resistance of AZ91 alloy. It was concluded that n-HAp coated AZ91 alloy could be a good candidate as a type of biodegradable implant material for biomedical applications.

  8. In vitro degradation behavior and cytocompatibility of biodegradable AZ31 alloy with PEO/HT composite coating.

    PubMed

    Tian, Peng; Liu, Xuanyong; Ding, Chuanxian

    2015-04-01

    Biodegradable magnesium-based implants have attracted much attention recently in orthopedic applications because of their good mechanical properties and biocompatibility. However, their rapid degradation in vivo will not only reduce their mechanical strength, but also induce some side effects, such as local alkalization and gas cavity, which may lead to a failure of the implant. In this work, a hydroxyapatite (HA) layer was prepared on plasma electrolytic oxidization (PEO) coating by hydrothermal treatment (HT) to fabricate a PEO/HT composite coating on biodegradable AZ31 alloy. The in vitro degradation behaviors of all samples were evaluated in simulated body fluid (SBF) and their surface cytocompatibility was also investigated by evaluating the adhesion and proliferation of osteoblast cells (MC3T3-E1). The results showed that the HA layer consisted of a dense inner layer and a needle-like outer layer, which successfully sealed the PEO coating. The in vitro degradation tests showed that the PEO/HT composite coating improved the corrosion resistance of AZ31 alloy in SBF, presenting nearly no severe local alkalization and hydrogen evolution. The lasting corrosion resistance of the PEO/HT composite coating may attribute to the new hydroxyapatite formation during the degradation process. Moreover, compared with AZ31 alloy and PEO coating, PEO/HT composite coating was more suitable for cells adhesion and proliferation, indicating improved surface cytocompatibility. The results show that the PEO/HT composite coating is promising as protective coating on biodegradable magnesium-based implants to enhance their corrosion resistance as well as improve their surface cytocompatibility for orthopedic applications.

  9. Sandstones, glaciers, burrows and transgressions: The Lower Palaeozoic of Jabel az-Zalmah, Al Kufrah Basin, Libya

    NASA Astrophysics Data System (ADS)

    Le Heron, Daniel Paul; Howard, James P.

    2012-03-01

    Field studies in the Jabel az-Zalmah region, at the northern flank of Al Kufrah Basin provide new insights into the stratigraphy and evolving depositional environments of Cambro-Ordovician through Devonian sediments. At the base of the succession, the Hawaz Formation is about 300 m thick and is characterised by frequently Skolithos-burrowed, fine to medium grained sandstones with occasional silty intervals and rare conglomerates deposited in a generally high-energy tidal shelf setting. Bioturbation is pervasive, and includes spectacular Cruziana traces produced by Early to Mid Ordovician trilobites at the bottom and the top of the Hawaz Formation respectively. These strata were incised during the late Ordovician (Hirnantian) glaciation. Ice sheets flowing over Jabel az-Zalmah cut a palaeo-topography of up to 100 m relief. This relief is overlain by a coarsening upward succession of clastic sedimentary rocks, recording re-advance of an ice sheet, which overrode the uppermost sandstones. Ice sheet retreat was accompanied by marine transgression and erosion, which left a thin transgressive lag-conglomerate, capped sharply by siltstones of the Tannezuft Formation. Progradation resumed after post-glacial maximum flooding, depositing tide, storm, and river-influenced parasequences of a major delta complex (200 m thick Acacus Formation). Fluvial incision, and the development of a disconformity, preceded the deposition of the Tadrart Formation (50 m thick), a succession of trough-cross bedded braided river deposits. Transgression, and the re-establishment of shallow or marginal marine systems, is represented by the extensively bioturbated Binem Formation in which Zoophycos burrows offer a tentative Middle Devonian stratigraphic fix. An understanding of the lithological character of the Lower Palaeozoic strata in Jabel az-Zalmah, together with the character of unconformities that punctuate the succession, will be vital for successful hydrocarbon exploration in this frontier

  10. Advanced characterization study of commercial conversion and electrocoating structures on magnesium alloys AZ31B and ZE10A

    DOE PAGES

    Brady, Michael P.; Leonard, Donovan N.; Meyer, III, Harry M.; ...

    2016-03-31

    The local metal-coating interface microstructure and chemistry formed on commercial magnesium alloys Mg–3Al–1Zn (AZ31B) and Mg–1Zn–0.25Zr–<0.5Nd (ZE10A, ZEK100 type) were analyzed as-chemical conversion coated with a commercial hexafluoro-titanate/zirconate type + organic polymer based treatment (Bonderite® 5200) and a commercial hexafluoro-zirconate type + trivalent chromium Cr3 + type treatment (Surtec® 650), and after the same conversion coatings followed by electrocoating with an epoxy based coating, Cathoguard® 525. Characterization techniques included scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and cross-section scanning transmission electron microscopy (STEM). Corrosion behavior was assessed in room temperature saturated aqueous Mg(OH)2 solution with 1 wt.% NaCl. Themore » goal of the effort was to assess the degree to which substrate alloy additions become enriched in the conversion coating, and how the conversion coating was impacted by subsequent electrocoating. Key findings included the enrichment of Al from AZ31B and Zr from ZE10A, respectively, into the conversion coating, with moderate corrosion resistance benefits for AZ31B when Al was incorporated. Varying degrees of increased porosity and modification of the initial conversion coating chemistry at the metal-coating interface were observed after electrocoating. These changes were postulated to result in degraded electrocoating protectiveness. As a result, these observations highlight the challenges of coating Mg, and the need to tailor electrocoating in light of potential degradation of the initial as-conversion coated Mg alloy surface.« less

  11. Advanced characterization study of commercial conversion and electrocoating structures on magnesium alloys AZ31B and ZE10A

    SciTech Connect

    Brady, Michael P.; Leonard, Donovan N.; Meyer, III, Harry M.; Song, Guang -Ling; Kitchen, Kris; Davis, Bruce; Thompson, J. K.; Unocic, K. A.; Elsentriecy, H. H.

    2016-03-31

    The local metal-coating interface microstructure and chemistry formed on commercial magnesium alloys Mg–3Al–1Zn (AZ31B) and Mg–1Zn–0.25Zr–<0.5Nd (ZE10A, ZEK100 type) were analyzed as-chemical conversion coated with a commercial hexafluoro-titanate/zirconate type + organic polymer based treatment (Bonderite® 5200) and a commercial hexafluoro-zirconate type + trivalent chromium Cr3 + type treatment (Surtec® 650), and after the same conversion coatings followed by electrocoating with an epoxy based coating, Cathoguard® 525. Characterization techniques included scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and cross-section scanning transmission electron microscopy (STEM). Corrosion behavior was assessed in room temperature saturated aqueous Mg(OH)2 solution with 1 wt.% NaCl. The goal of the effort was to assess the degree to which substrate alloy additions become enriched in the conversion coating, and how the conversion coating was impacted by subsequent electrocoating. Key findings included the enrichment of Al from AZ31B and Zr from ZE10A, respectively, into the conversion coating, with moderate corrosion resistance benefits for AZ31B when Al was incorporated. Varying degrees of increased porosity and modification of the initial conversion coating chemistry at the metal-coating interface were observed after electrocoating. These changes were postulated to result in degraded electrocoating protectiveness. As a result, these observations highlight the challenges of coating Mg, and the need to tailor electrocoating in light of potential degradation of the initial as-conversion coated Mg alloy surface.

  12. Constructing cities, deconstructing scaling laws.

    PubMed

    Arcaute, Elsa; Hatna, Erez; Ferguson, Peter; Youn, Hyejin; Johansson, Anders; Batty, Michael

    2015-01-06

    Cities can be characterized and modelled through different urban measures. Consistency within these observables is crucial in order to advance towards a science of cities. Bettencourt et al. have proposed that many of these urban measures can be predicted through universal scaling laws. We develop a framework to consistently define cities, using commuting to work and population density thresholds, and construct thousands of realizations of systems of cities with different boundaries for England and Wales. These serve as a laboratory for the scaling analysis of a large set of urban indicators. The analysis shows that population size alone does not provide us enough information to describe or predict the state of a city as previously proposed, indicating that the expected scaling laws are not corroborated. We found that most urban indicators scale linearly with city size, regardless of the definition of the urban boundaries. However, when nonlinear correlations are present, the exponent fluctuates considerably.

  13. The dynamics of city formation*

    PubMed Central

    Henderson, J. Vernon; Venables, Anthony J.

    2013-01-01

    This paper examines city formation in a country whose urban population is growing steadily over time, with new cities required to accommodate this growth. In contrast to most of the literature there is immobility of housing and urban infrastructure, and investment in these assets is taken on the basis of forward-looking behavior. In the presence of these fixed assets cities form sequentially, without the population swings in existing cities that arise in current models, but with swings in house rents. Equilibrium city size, absent government, may be larger or smaller than is efficient, depending on how urban externalities vary with population. Efficient formation of cities with internalization of externalities involves local government intervention and borrowing to finance development. The paper explores the institutions required for successful local government intervention. PMID:25089087

  14. Wetting and Interfacial Characteristics of Mg AZ61 Alloy/Galvanized Steel in Cold Metal Transfer Process

    NASA Astrophysics Data System (ADS)

    Lin, Qiaoli; Yang, Fan; Cao, Rui; Chen, Jianhong; Guo, Tingbiao

    2015-09-01

    The dynamic sessile drop method was used to study the wetting behavior of galvanized steel by molten Mg AZ61 alloy under cold metal transfer condition. The interfacial microstructures were also analyzed by using scanning electron microscope and energy dispersive spectrometry. The observed results showed that the wetting behavior was directly determined by the wire feed speed (or the heat input). The Al-Fe intermetallic layer and Zn-rich zone were observed both at the interface and at the close of triple line. The formations of these interfacial characteristics satisfy the thermodynamic characteristic of Mg-Al/Fe and Mg-Zn/Fe systems.

  15. SUBMILLIMETER ARRAY IDENTIFICATION OF THE MILLIMETER-SELECTED GALAXY SSA22-AzTEC1: A PROTOQUASAR IN A PROTOCLUSTER?

    SciTech Connect

    Tamura, Y.; Iono, D.; Hatsukade, B.; Kawabe, R.; Wilner, D. J.; Chung, A.; Kajisawa, M.; Hayashino, T.; Ichikawa, T.; Uchimoto, Y. K.; Ikarashi, S.; Kohno, K.; Alexander, D. M.; Lehmer, B. D.; Matsuda, Y.; Ezawa, H.; Nakanishi, K.; Takata, T.; Hughes, D. H.; Wilson, G. W.

    2010-12-01

    We present results from Submillimeter Array (SMA) 860 {mu}m subarcsecond astrometry and multiwavelength observations of the brightest millimeter (S{sub 1.1mm} = 8.4 mJy) source, SSA22-AzTEC1, found near the core of the SSA22 protocluster that is traced by Ly{alpha}-emitting galaxies at z = 3.09. We identify a 860 {mu}m counterpart with a flux density of S{sub 860{sub {mu}m}} = 12.2 {+-} 2.3 mJy and absolute positional accuracy that is better than 0.''3. At the SMA position, we find radio-to-mid-infrared counterparts, whilst no object is found in Subaru optical and near-infrared deep images at wavelengths {<=}1 {mu}m (J > 25.4 in AB, 2{sigma}). The photometric redshift estimate, using flux densities at {>=}24 {mu}m, indicates z{sub phot} = 3.19{sup +0.26}{sub -0.35}, consistent with the protocluster redshift. We then model the near-to-mid-infrared spectral energy distribution (SED) of SSA22-AzTEC1, and find that the SED modeling requires a large extinction (A{sub V} {approx} 3.4 mag) of starlight from a stellar component with M{sub star} {approx} 10{sup 10.9} M{sub sun}, assuming z = 3.1. Additionally, we find a significant X-ray counterpart with a very hard spectrum ({Gamma}{sub eff} = -0.34{sup +0.57}{sub -0.61}), strongly suggesting that SSA22-AzTEC1 harbors a luminous active galactic nuclei (AGNs; L{sub X} {approx} 3 x 10{sup 44} erg s{sup -1}) behind a large hydrogen column (N{sub H} {approx} 10{sup 24} cm{sup -2}). The AGN, however, is responsible for only {approx}10% of the bolometric luminosity of the host galaxy, and therefore the star formation activity likely dominates the submillimeter emission. It is possible that SSA22-AzTEC1 is the first example of a protoquasar growing at the bottom of the gravitational potential underlying the SSA22 protocluster.

  16. A Tale of Two Machines: A review of the BLAST meeting, Tucson, AZ, January 20–24, 2013

    PubMed Central

    Josenhans, Christine; Jung, Kirsten; Rao, Christopher V.; Wolfe, Alan J.

    2013-01-01

    Since its inception, Bacterial Locomotion and Signal Transduction (BLAST) meetings have been the place to exchange and share the latest developments in the field of bacterial signal transduction and motility. At the 12th BLAST meeting, held last January in Tucson AZ, researchers from all over the world met to report and discuss progress in diverse aspects of the field. The majority of these advances, however, came at the level of atomic level structures and their associated mechanisms. This was especially true of the biological machines that sense and respond to environmental changes. PMID:24125587

  17. A tale of two machines: a review of the BLAST meeting, Tucson, AZ, 20-24 January 2013.

    PubMed

    Josenhans, Christine; Jung, Kirsten; Rao, Christopher V; Wolfe, Alan J

    2014-01-01

    Since its inception, Bacterial Locomotion and Signal Transduction (BLAST) meetings have been the place to exchange and share the latest developments in the field of bacterial signal transduction and motility. At the 12th BLAST meeting, held last January in Tucson, AZ, researchers from all over the world met to report and discuss progress in diverse aspects of the field. The majority of these advances, however, came at the level of atomic level structures and their associated mechanisms. This was especially true of the biological machines that sense and respond to environmental changes.

  18. The study of microstructure and mechanical properties of twin-roll cast AZ31 magnesium alloy after constrained groove pressing

    NASA Astrophysics Data System (ADS)

    Zimina, M.; Bohlen, J.; Letzig, D.; Kurz, G.; Cieslar, M.; Zník, J.

    2014-08-01

    Microstructure investigation and microhardness mapping were done on the material with ultra-fine grained structure prepared by constrained groove pressing of twin-roll cast AZ31 magnesium strips. The microstructure observations showed significant drop of the grain size from 200 gm to 20 gm after constrained groove pressing. Moreover, the heterogeneities in the microhardness along the cross-section observed in the as-cast strip were replaced by the bands of different microhardness in the constrained groove pressed material. It is shown that the constrained groove pressing technique is a good tool for the grain refinement of magnesium alloys.

  19. Influence of exposure differences on city-to-city heterogeneity ...

    EPA Pesticide Factsheets

    Multi-city population-based epidemiological studies have observed heterogeneity between city-specific fine particulate matter (PM2.5)-mortality effect estimates. These studies typically use ambient monitoring data as a surrogate for exposure leading to potential exposure misclassification. The level of exposure misclassification can differ by city affecting the observed health effect estimate. The objective of this analysis is to evaluate whether previously developed residential infiltration-based city clusters can explain city-to-city heterogeneity in PM2.5 mortality risk estimates. In a prior paper 94 cities were clustered based on residential infiltration factors (e.g. home age/size, prevalence of air conditioning (AC)), resulting in 5 clusters. For this analysis, the association between PM2.5 and all-cause mortality was first determined in 77 cities across the United States for 2001–2005. Next, a second stage analysis was conducted evaluating the influence of cluster assignment on heterogeneity in the risk estimates. Associations between a 2-day (lag 0–1 days) moving average of PM2.5 concentrations and non-accidental mortality were determined for each city. Estimated effects ranged from −3.2 to 5.1% with a pooled estimate of 0.33% (95% CI: 0.13, 0.53) increase in mortality per 10 μg/m3 increase in PM2.5. The second stage analysis determined that cluster assignment was marginally significant in explaining the city-to-city heterogeneity. The health effe

  20. 78 FR 23866 - Safety Zone; Crescent City 4th of July Fireworks; Crescent City Harbor, Crescent City, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-23

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Crescent City 4th of July Fireworks; Crescent City Harbor, Crescent City, CA AGENCY: Coast Guard, DHS. ACTION: Notice of proposed rulemaking... Crescent City, CA in support of the Crescent City 4th of July Fireworks on July 4, 2013. This safety...

  1. Experimental and Numerical Study on the Deformation Mechanism in AZ31B Mg Alloy Sheets Under Pulsed Electric-Assisted Tensile and Compressive Tests

    NASA Astrophysics Data System (ADS)

    Lee, Jinwoo; Kim, Se-Jong; Lee, Myoung-Gyu; Song, Jung Han; Choi, Seogou; Han, Heung Nam; Kim, Daeyong

    2016-06-01

    The uniaxial tensile and compressive stress-strain responses of AZ31B magnesium alloy sheet under pulsed electric current are reported. Tension and compression tests with pulsed electric current showed that flow stresses dropped instantaneously when the electric pulses were applied. Thermo-mechanical-electrical finite element analyses were also performed to investigate the effects of Joule heating and electro-plasticity on the flow responses of AZ31B sheets under electric-pulsed tension and compression tests. The proposed finite element simulations could reproduce the measured uniaxial tensile and compressive stress-strain curves under pulsed electric currents, when the temperature-dependent flow stress hardening model and thermal properties of AZ31B sheet were properly described in the simulations. In particular, the simulation results that fit best with experimental results showed that almost 100 pct of the electric current was subject to transform into Joule heating during electrically assisted tensile and compressive tests.

  2. Complete Mitochondrial and Plastid Genomes of the Green Microalga Trebouxiophyceae sp. Strain MX-AZ01 Isolated from a Highly Acidic Geothermal Lake

    PubMed Central

    Martínez-Romero, Esperanza

    2012-01-01

    We report the complete organelle genome sequences of Trebouxiophyceae sp. strain MX-AZ01, an acidophilic green microalga isolated from a geothermal field in Mexico. This eukaryote has the remarkable ability to thrive in a particular shallow lake with emerging hot springs at the bottom, extremely low pH, and toxic heavy metal concentrations. Trebouxiophyceae sp. MX-AZ01 represents one of few described photosynthetic eukaryotes living in such a hostile environment. The organelle genomes of Trebouxiophyceae sp. MX-AZ01 are remarkable. The plastid genome sequence currently presents the highest G+C content for a trebouxiophyte. The mitochondrial genome sequence is the largest reported to date for the Trebouxiophyceae class of green algae. The analysis of the genome sequences presented here provides insight into the evolution of organelle genomes of trebouxiophytes and green algae. PMID:23104370

  3. Mexico City Subsidence

    NASA Astrophysics Data System (ADS)

    Osmanoglu, B.; Dixon, T. H.; Cabral-Cano, E.; Wdowinski, S.

    2008-12-01

    Many parts of Mexico City are undergoing rapid subsidence due to extraction of ground water in excess of natural recharge. We use PSInSAR (Persistent Scatterer InSAR) to investigate the link between surface deformation and ground water withdrawal. From 23 Envisat acquisitions, we obtain a time-series of surface deformation between January 2004 and July 2006 showing that the eastern part of Mexico City presents a high subsidence rate as high as 30 cm/year. This subsidence is clearly tied to declining ground water levels. We use TU Delft's Doris and PSI Toolbox for interferogram generation and PS processing. Assuming constant subsidence rates, we have obtained a dense, coherent deformation map throughout the area. Comparison between GPS and PSInSAR inferred rates show agreement in the longer term signal; we will also show initial results of GPS/PSInSAR comparison on shorter time scales. The high density of persistent scatterers allows us to detect differential deformation of urban infrastructure. Our analysis indicates that in some cases the rate of an individual persistent scatterer can differ about 3-4 cm/yr from local deformation. While some bigger buildings show slower subsidence, others have faster rates. It is important to note that in some large buildings we detected differential vertical motion, suggesting that these buildings are subject to shear stresses associated with local deformation.

  4. A Protein Complex Containing the Conserved Swi2/Snf2-Related ATPase Swr1p Deposits Histone Variant H2A.Z into Euchromatin

    PubMed Central

    Kobor, Michael. S; Venkatasubrahmanyam, Shivkumar; Meneghini, Marc D; Gin, Jennifer W; Jennings, Jennifer L; Link, Andrew J

    2004-01-01

    The conserved histone variant H2A.Z functions in euchromatin to antagonize the spread of heterochromatin. The mechanism by which histone H2A is replaced by H2A.Z in the nucleosome is unknown. We identified a complex containing 13 different polypeptides associated with a soluble pool of H2A.Z in Saccharomyces cerevisiae. This complex was designated SWR1-Com in reference to the Swr1p subunit, a Swi2/Snf2-paralog. Swr1p and six other subunits were found only in SWR1-Com, whereas six other subunits were also found in the NuA4 histone acetyltransferase and/or the Ino80 chromatin remodeling complex. H2A.Z and SWR1 were essential for viability of cells lacking the EAF1 component of NuA4, pointing to a close functional connection between these two complexes. Strikingly, chromatin immunoprecipitation analysis of cells lacking Swr1p, the presumed ATPase of the complex, revealed a profound defect in the deposition of H2A.Z at euchromatic regions that flank the silent mating type cassette HMR and at 12 other chromosomal sites tested. Consistent with a specialized role for Swr1p in H2A.Z deposition, the majority of the genome-wide transcriptional defects seen in swr1Δ cells were also found in htz1Δ cells. These studies revealed a novel role for a member of the ATP-dependent chromatin remodeling enzyme family in determining the region-specific histone subunit composition of chromatin in vivo and controlling the epigenetic state of chromatin. Metazoan orthologs of Swr1p (Drosophila Domino; human SRCAP and p400) may have analogous functions. PMID:15045029

  5. A protein complex containing the conserved Swi2/Snf2-related ATPase Swr1p deposits histone variant H2A.Z into euchromatin.

    PubMed

    Kobor, Michael S; Venkatasubrahmanyam, Shivkumar; Meneghini, Marc D; Gin, Jennifer W; Jennings, Jennifer L; Link, Andrew J; Madhani, Hiten D; Rine, Jasper

    2004-05-01

    The conserved histone variant H2A.Z functions in euchromatin to antagonize the spread of heterochromatin. The mechanism by which histone H2A is replaced by H2A.Z in the nucleosome is unknown. We identified a complex containing 13 different polypeptides associated with a soluble pool of H2A.Z in Saccharomyces cerevisiae. This complex was designated SWR1-Com in reference to the Swr1p subunit, a Swi2/Snf2-paralog. Swr1p and six other subunits were found only in SWR1-Com, whereas six other subunits were also found in the NuA4 histone acetyltransferase and/or the Ino80 chromatin remodeling complex. H2A.Z and SWR1 were essential for viability of cells lacking the EAF1 component of NuA4, pointing to a close functional connection between these two complexes. Strikingly, chromatin immunoprecipitation analysis of cells lacking Swr1p, the presumed ATPase of the complex, revealed a profound defect in the deposition of H2A.Z at euchromatic regions that flank the silent mating type cassette HMR and at 12 other chromosomal sites tested. Consistent with a specialized role for Swr1p in H2A.Z deposition, the majority of the genome-wide transcriptional defects seen in swr1Delta cells were also found in htz1Delta cells. These studies revealed a novel role for a member of the ATP-dependent chromatin remodeling enzyme family in determining the region-specific histone subunit composition of chromatin in vivo and controlling the epigenetic state of chromatin. Metazoan orthologs of Swr1p (Drosophila Domino; human SRCAP and p400) may have analogous functions.

  6. Pre-clinical validation of a novel alpha-7 nicotinic receptor radiotracer, [(3)H]AZ11637326: target localization, biodistribution and ligand occupancy in the rat brain.

    PubMed

    Maier, Donna L; Hill, Geraldine; Ding, Min; Tuke, David; Einstein, Emily; Gurley, David; Gordon, John C; Bock, Mary J; Smith, Jeff S; Bialecki, Russell; Eisman, Mark; Elmore, Charles S; Werkheiser, Jennifer L

    2011-01-01

    The alpha-7 neuronal nicotinic receptor is a novel pharmacological target for psychiatric and cognitive disorders. Selective radiotracer tools for pre-clinical receptor occupancy can facilitate the interpretation of the biological actions of small molecules at a target receptor. We discovered a high affinity nicotinic alpha-7 subtype-selective ligand, AZ11637326, with physical-chemical and pharmacokinetic properties suitable for an in vivo radioligand tool. [(3)H]AZ11637326 synthesis by tritiodehalogenation of the corresponding tribromide precursor yielded a high specific activity radiotracer with high affinity alpha-7 receptor binding in the rat hippocampus determined by autoradiography (Kd = 0.2 nM). When [(3)H]AZ11637326 was administered to rats by intravenous bolus, rapid uptake was measured in the brain followed by a 3-4 fold greater specific binding in regions containing the alpha-7 receptor (frontal cortex, hippocampus, hypothalamus and midbrain) when compared to non-target regions (striatum and cerebellum). Systemic administration of the high affinity alpha-7 receptor antagonist, methyllycaconitine (MLA), or pretreatment with alpha-7 selective agonists (AR-R17779, PyrQTC, DBCO-4-POM, and DBCO-3-POM) significantly blocked the alpha-7 specific binding of [(3)H]AZ11637326 in the rat brain. The rank order of ligand ED(50) values for in vivo alpha-7 receptor occupancy in rat hippocampus was: DBCO-4-POM > DBCO-3-POM ∼ MLA > PyrQTC > AR-R17779. The occupancy affinity shift was consistent with in vitro binding affinity in autoradiography. Our studies established the optimal conditions for [(3)H]AZ11637326 in vivo specific binding in the rat brain and support the use of [(3)H]AZ11637326 as a pre-clinical tool for assessment of novel alpha-7 compounds in drug discovery.

  7. Kid-Friendly Cities Report Card, 2001.

    ERIC Educational Resources Information Center

    Polansky, Lee S., Ed.

    2001-01-01

    This report examines the health and wellbeing of children in the United States' largest cities, covering every city with a population of 100,000 or more, as well as the largest cities in states without any cities of this size. Research shows that many cities are becoming more child-friendly, with better access to good education, jobs, and health…

  8. Smart cities of the future

    NASA Astrophysics Data System (ADS)

    Batty, M.; Axhausen, K. W.; Giannotti, F.; Pozdnoukhov, A.; Bazzani, A.; Wachowicz, M.; Ouzounis, G.; Portugali, Y.

    2012-11-01

    Here we sketch the rudiments of what constitutes a smart city which we define as a city in which ICT is merged with traditional infrastructures, coordinated and integrated using new digital technologies. We first sketch our vision defining seven goals which concern: developing a new understanding of urban problems; effective and feasible ways to coordinate urban technologies; models and methods for using urban data across spatial and temporal scales; developing new technologies for communication and dissemination; developing new forms of urban governance and organisation; defining critical problems relating to cities, transport, and energy; and identifying risk, uncertainty, and hazards in the smart city. To this, we add six research challenges: to relate the infrastructure of smart cities to their operational functioning and planning through management, control and optimisation; to explore the notion of the city as a laboratory for innovation; to provide portfolios of urban simulation which inform future designs; to develop technologies that ensure equity, fairness and realise a better quality of city life; to develop technologies that ensure informed participation and create shared knowledge for democratic city governance; and to ensure greater and more effective mobility and access to opportunities for urban populations. We begin by defining the state of the art, explaining the science of smart cities. We define six scenarios based on new cities badging themselves as smart, older cities regenerating themselves as smart, the development of science parks, tech cities, and technopoles focused on high technologies, the development of urban services using contemporary ICT, the use of ICT to develop new urban intelligence functions, and the development of online and mobile forms of participation. Seven project areas are then proposed: Integrated Databases for the Smart City, Sensing, Networking and the Impact of New Social Media, Modelling Network Performance

  9. Source-zone characterization of a chlorinated-solvent contaminated Superfund site in Tucson, AZ.

    PubMed

    Brusseau, M L; Nelson, N T; Zhang, Z; Blue, J E; Rohrer, J; Allen, T

    2007-02-20

    An extensive site-characterization project was conducted at a large chlorinated-solvent contaminated Superfund site in Tucson, AZ. The project consisted of several components, including traditional site-characterization activities, tracer tests, laboratory experiments conducted with core material collected from the site, and mathematical modeling. The primary focus of the work presented herein is the analysis of induced-gradient contaminant elution tests conducted in a source zone at the site, investigation of the potential occurrence of immiscible liquid in the saturated zone, characterization of the relationship between mass flux reduction and mass removal, and evaluation of the impact of source-zone management on site remediation. The results of the present study, along with those of prior work, indicate that immiscible liquid is likely present in the saturated zone at the site source zones. Extensive tailing and rebound was observed for the contaminant-elution tests, indicating nonideal transport and mass-transfer behavior. The elution data were analyzed with a source-zone-scale mathematical model, and the results indicated that nonideal immiscible-liquid dissolution was the primary cause of the observed behavior. The time-continuous relationship between mass flux reduction and mass removal associated with the plume-scale pump-and-treat operation exhibited an initial large drop in mass flux with minimal mass removed, followed by a period of minimal mass flux reduction and a second period of large reduction. This behavior reflects the impact of both source-zone and aqueous-plume mass removal dynamics. Ultimately, a greater than 90% reduction in mass flux was achieved for a mass removal of approximately 50%. The influence of source-zone management on site remediation was evaluated by conducting two predictive simulations, one for which the source zones were controlled and one for which they were not. A plume-scale model was used to simulate the composite

  10. A Remotely Sensed and Paleomagnetic Perspective on the Bonelli Tuff of NW AZ and SE CA

    NASA Astrophysics Data System (ADS)

    Gomez, C. D.

    2015-12-01

    The southern Black and Cerbat Mountains of NW AZ and the Sacramento Mountains of SE CA preserve ignimbrites associated with multiple episodes of volcanic activity that span at least a million years. Unraveling the stratrigraphy of these deposits, as well as their eruptive centers, is critical for constraining the volcanic history of this ignimbrite, the 18.8 Ma Peach Spring Tuff, is the recently identified 17.7 Ma Tuff of Bonelli House (TB) (Ferguson & Cook 2015) and may also occur in the southern Black and Sacramento Mountains. To help determine the extent and possible source of the TB, we have performed a combined remote sensing and paleomagnetic study of this unit, including possible correlatives. Paleomagnetic work involved Remanence and anisotropic magnetic susceptibility methods. Drill samples were collected and processed at Scripps Institute of Oceanography & Pomona College. An AC current was run to obtain the Paleomag current, as opposed to the traditional of heating up the cores at specific intervals. Sacramento Mountains samples produced an average direction of 200.9 / -26.4, which contrasts the Peach Spring Tuff paleodirection of 036.4/33 (Wells & Hillhouse, 1989). An AMS direction was determined using a MFK1 Kappabridge instrument and consistently showed similar flow direction to that of the PST. In compiling our data on a map, we took into account the Whipple Detachment Fault, ~40 km westward (Lister & Davis, 1989). We were able to identify a spectral signature and remnant paleomagnetic direction for the TB and identify potential additional outcrops in the southern Black mountains. AMS showed us that the ignimbrites originated from a source in the Silver Creek Caldera, which may indicate the PST at TB were produced from a similar source. The remnant paleomagnetic direction allows us to closely correlate these tuff units as occurring within a similar timeframe. The contrasting paleodirection of the TB and the PST allows us to confidently say that the

  11. Flash Floods, Sediment Transport, and the Geomorphic Transformation of Moenkopi Wash, AZ

    NASA Astrophysics Data System (ADS)

    Dean, D. J.; Topping, D. J.

    2015-12-01

    Fine sediment is a crucial resource to the Colorado River ecosystem in Grand Canyon National Park, AZ. Much of the fine sediment is supplied during flash floods on the Little Colorado River (LCR) and its tributary, Moenkopi Wash (MW). Concentrations of suspended-sediment during flash floods on MW are often greater than 200,000 mg/L, and have exceeded 490,000 mg/L. Historically, the highest concentrations of suspended-sand measured in the LCR have been the result of flooding on MW. Over the last 65 years, widespread geomorphic change on MW has occurred that has likely altered the amount of fine sediment supplied to the LCR. Geomorphic changes include channel-bed aggradation, channel narrowing, increases in sinuosity, and non-native vegetation colonization of the banks and floodplains. Channel-bed aggradation has exceeded 2m, and the channel has narrowed by more than 66% in some areas. In these areas, the combination of aggradation and narrowing has resulted in the loss of cross-section area by nearly 90%. The direct causes of these changes are unclear and may include changes in stream flow and sediment supply caused by human activities and/or climate, and the increased sediment trapping efficiency of vegetation. However, the causes are likely a complex combination of all of the above. Although stream gages have existed on Moenkopi Wash since 1926, frequent changes in gaging locations combined with substantial flood attenuation during flash floods make it difficult to compile a long-term flow record at a single location. Therefore, we are using a kinematic-wave model to route floods between the historic gaging locations in order to construct a long-term flow record near the mouth of Moenkopi Wash. Analyses of the long-term flow record, combined with analyses of suspended-sediment transport are used to evaluate how the geomorphic transformation of Moenkopi Wash has affected sediment delivery to the Little Colorado and the Colorado Rivers.

  12. Source-zone characterization of a chlorinated-solvent contaminated Superfund site in Tucson, AZ

    NASA Astrophysics Data System (ADS)

    Brusseau, M. L.; Nelson, N. T.; Zhang, Z.; Blue, J. E.; Rohrer, J.; Allen, T.

    2007-02-01

    An extensive site-characterization project was conducted at a large chlorinated-solvent contaminated Superfund site in Tucson, AZ. The project consisted of several components, including traditional site-characterization activities, tracer tests, laboratory experiments conducted with core material collected from the site, and mathematical modeling. The primary focus of the work presented herein is the analysis of induced-gradient contaminant elution tests conducted in a source zone at the site, investigation of the potential occurrence of immiscible liquid in the saturated zone, characterization of the relationship between mass flux reduction and mass removal, and evaluation of the impact of source-zone management on site remediation. The results of the present study, along with those of prior work, indicate that immiscible liquid is likely present in the saturated zone at the site source zones. Extensive tailing and rebound was observed for the contaminant-elution tests, indicating nonideal transport and mass-transfer behavior. The elution data were analyzed with a source-zone-scale mathematical model, and the results indicated that nonideal immiscible-liquid dissolution was the primary cause of the observed behavior. The time-continuous relationship between mass flux reduction and mass removal associated with the plume-scale pump-and-treat operation exhibited an initial large drop in mass flux with minimal mass removed, followed by a period of minimal mass flux reduction and a second period of large reduction. This behavior reflects the impact of both source-zone and aqueous-plume mass removal dynamics. Ultimately, a greater than 90% reduction in mass flux was achieved for a mass removal of approximately 50%. The influence of source-zone management on site remediation was evaluated by conducting two predictive simulations, one for which the source zones were controlled and one for which they were not. A plume-scale model was used to simulate the composite

  13. Salt Lake City, Utah

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The 2002 Winter Olympics are hosted by Salt Lake City at several venues within the city, in nearby cities, and within the adjacent Wasatch Mountains. This simulated natural color image presents a late spring view of north central Utah that includes all of the Olympic sites. The image extends from Ogden in the north, to Provo in the south; and includes the snow-capped Wasatch Mountains and the eastern part of the Great Salt Lake.

    This image was acquired on May 28, 2000 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The Terra mission is part of NASA's Earth Science Enterprise, a long-term research and technology program designed to examine Earth's land, oceans, atmosphere, ice and life as a total integrated system.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution

  14. Hydroxyapatite coating on biodegradable AZ31 and Mg-Ca alloys prepared by RF-magnetron sputtering

    SciTech Connect

    Mukhametkaliyev, T. Surmeneva, M. Surmenev, R.; Mathan, B. K.

    2015-11-17

    A thin film of hydroxyapatite (HA) was deposited on AZ31 and Mg-Ca alloys by using radio frequency (RF) magnetron sputtering. The thickness of the HA coating was determined to be 750 nm. The phase composition, microstructure, and surface morphology of the HA coatings were investigated using X-ray diffraction and scanning electron microscopy. In vitro degradation behaviour of the HA coated alloys was evaluated in simulated body fluid (SBF) and 3.5wt.% NaCl solution using electrochemical method. The coatings homogeneously covered the entire surface of the substrates. The coating structure corresponded to a nanostructured HA. The ultrathin coating significantly improved the degradation resistance of the alloy. Nanocrystalline HA coating significantly improved the corrosion resistance of the Mg-Ca and AZ31 magnesium alloys. The polarization resistance (Rp) of the coated Mg-Ca alloy was more than two-order of magnitude higher and the corrosion current density I{sub corr} reduced by ∼ 98% as compared to the base alloy.

  15. Characterization and degradation behavior of AZ31 alloy surface modified by bone-like hydroxyapatite for implant applications

    NASA Astrophysics Data System (ADS)

    Wen, Cuilian; Guan, Shaokang; Peng, Li; Ren, Chenxing; Wang, Xiang; Hu, Zhonghua

    2009-04-01

    Hydroxyapatite (HA) coating on AZ31 alloy substrate was prepared by a cathodic electrodeposition method. The as-deposited specimen was then post-treated with hot alkali solution to improve the corrosion resistance and bioactivity for implant applications. The microstructure and composition of HA coating, as well as its degradation behavior in simulated body fluid (SBF) were investigated. It reveals that the as-deposited coating consists of dicalcium phosphate dehydrate (DCPD, CaHPO 4·2H 2O) and HA. While 10 μm-thick nanowhisker HA coatings doped with Na +, Mg +, HPO 42-and CO 32- can be found after NaOH alkali treatment, which exhibits a very similar composition of natural bone. The post-treated coating was composed of needle-like particles with 1000 nm in length and 35 nm in diameter, having a slenderness ratio of about 28.6. Electrochemical tests shows that the Ecorr of Mg substrate significantly increased from -1.6 to -1.42 V after surface modified by HA coatings. There was obvious mass gain on post-treated specimen immersed in SBF during the first 30 days due to the Ca-P-Mg deposition. The HA-coated AZ31 alloy could slow down the degradation rate and effectively induce the deposition of Ca-P-Mg apatite in SBF, showing a good bioactivity.

  16. Evaluating the Superplastic Flow of a Magnesium AZ31 Alloy Processed by Equal-Channel Angular Pressing

    NASA Astrophysics Data System (ADS)

    Figueiredo, Roberto B.; Langdon, Terence G.

    2014-07-01

    Experiments show that the magnesium AZ31 (Mg-3 pct Al-1 pct Zn) alloy exhibits excellent superplastic properties at 623 K (350 °C) after processing by equal-channel angular pressing using a die with a channel angle of 135 deg and a range of decreasing processing temperatures from 473 K to 413 K (200 °C to 140 °C). A maximum elongation to failure of ~1200 pct was achieved in this alloy at a tensile strain rate of 1.0 × 10-4 s-1. Microstructural inspection showed evidence for cavity formation and grain growth during tensile testing with the grain growth leading to significant strain hardening. An examination of the experimental data shows that grain boundary sliding is dominant during superplastic flow. Furthermore, a comprehensive review of the present results and extensive published data for the AZ31 alloy shows the exponent of the inverse grain size is given by p ≈ 2 which is consistent with grain boundary sliding as the rate-controlling flow mechanism.

  17. Modeling the Stress-Strain Behavior and Hot Tearing during Direct Chill Casting of an AZ31 Magnesium Billet

    NASA Astrophysics Data System (ADS)

    Hao, H.; Maijer, D. M.; Wells, M. A.; Phillion, Andre; Cockcroft, S. L.

    2010-08-01

    Quantitative knowledge of the thermal mechanical history experienced during direct chill (DC) casting aids the scientific understanding of the process especially in terms of defect formation such as hot tearing. In this work, a thermomechanical finite element (FE) model has been developed to simulate the DC casting of magnesium alloy AZ31 billets. The mathematical model simulates the evolution of temperature, stress, and strain within the billet during an industrial DC casting process. These quantities were then used to calculate the evolution in pressure, and hence hot tearing tendency, within the semisolid regime via the Rappaz-Drezet-Gremaud (RDG) criterion. The temperature predictions were validated against experimental thermocouple data measured during a plant trial at an industrial magnesium DC casting facility. In addition, the residual elastic strains predicted by the model were compared to residual strain measurements made at the Canadian Neutron Beam Centre (CNBC) using a magnesium billet produced during the industrial casting trial. The validated model was then used to quantitatively assess the impact of casting speed on the hot tearing tendency in AZ31 billets.

  18. Poly(L-lactic acid)/hydroxyapatite/collagen composite coatings on AZ31 magnesium alloy for biomedical application.

    PubMed

    Wang, Zhen-Lin; Yan, Yu-Hua; Wan, Tao; Yang, Hui

    2013-10-01

    Surface modification of biomedical magnesium alloy using composite coating shows an attemptable approach for the development of Mg-based biomaterials with excellent cytocompatibility. Hydroxyapatite/collagen composite was preliminarily fabricated by biomineralization, the bioactive poly(l-lactic acid)/hydroxyapatite/collagen composite coatings were spin coated on AZ31 magnesium alloy using poly(l-lactic acid) solution mixed with hydroxyapatite/collagen particles, and the resultant materials and coatings were characterized in structure and related properties; furthermore, the in vitro degradation behavior of modified magnesium alloy in 1.5-fold Hank's solution was investigated. The results show that hydroxyapatite/collagen composite achieved chemical bonding between hydroxyapatite and collagen similar to natural bone; composite coatings on AZ31 magnesium alloy retained the bioactive functional groups of the componential materials and improved the corrosion resistance of Mg alloy; the mass fraction of hydroxyapatite/collagen particles incorporated into the composite affected the porous structure, interfacial adhesion and thus the corrosion resistance of the composite coating due to phase separation as well as volume concentration effects of polymer solution. Composite coatings suppressed the sharp rising of pH value and the released Mg(2+) from substrate to extensive degree, and the degradation behavior of the modified magnesium alloy was supposed to be correlated to microstructure of the coating as well as the synergistic reactions among alkaline- and acidic-degraded products.

  19. Darkening effect on AZ31B magnesium alloy surface induced by nanosecond pulse Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Guan, Y. C.; Zhou, W.; Zheng, H. Y.; Li, Z. L.

    2013-09-01

    Permanent darkening effect was achieved on surface of AZ31B Mg alloy irradiated with nanosecond pulse Nd:YAG laser, and special attention was made to examine how surface structure as well as oxidation affect the darkening effect. Experiments were carried out to characterize morphological evolution and chemical composition of the irradiated areas by optical reflection spectrometer, Talysurf surface profiler, SEM, EDS, and XPS. The darkening effect was found to be occurred at the surface under high laser energy. Optical spectra showed that the induced darkening surface was uniform over the spectral range from 200 nm to 1100 nm. SEM and surface profiler showed that surface morphology of darkening areas consisted of large number of micron scale cauliflower-like clusters and protruding particles. EDS and XPS showed that compared to non-irradiated area, oxygen content at the darkening areas increased significantly. It was proposed a mechanism that involved trapping of light in the surface morphology and chemistry variation of irradiated areas to explain the laser-induced darkening effect on AZ31B Mg alloy.

  20. Microstructure and corrosion behavior of laser surface-treated AZ31B Mg bio-implant material.

    PubMed

    Wu, Tso-Chang; Ho, Yee-Hsien; Joshi, Sameehan S; Rajamure, Ravi S; Dahotre, Narendra B

    2017-03-02

    Although magnesium and magnesium alloys are considered biocompatible and biodegradable, they suffer from poor corrosion performance in the human body environment. In light of this, surface modification via rapid surface melting of AZ31B Mg alloy using a continuous-wave Nd:YAG laser was conducted. Laser processing was performed with laser energy ranging from 1.06 to 3.18 J/mm(2). The corrosion behavior in simulated body fluid of laser surface-treated and untreated AZ31B Mg alloy samples was evaluated using electrochemical technique. The effect of laser surface treatment on phase and microstructure evolution was evaluated using X-ray diffraction and scanning electron microscopy. Microstructure examination revealed grain refinement as well as formation and uniform distribution of Mg17Al12 phase along the grain boundary for laser surface-treated samples. Evolution of such unique microstructure during laser surface treatment indicated enhancement in the corrosion resistance of laser surface-treated samples compared to untreated alloy.

  1. Effects of loading methods on microstructure of diffusion welded joint of AZ31B/Cu with Ni interlayer

    NASA Astrophysics Data System (ADS)

    Du, S. M.; Zhang, Y. Q.; Du, C.; Hu, J.

    2017-02-01

    Diffusion brazing was carried out to weld AZ31B magnesium alloy and copper with Ni foil interlayer under different loading methods that are divided into intermittent gradient pressure, gradient pressure and constant pressure. The microstructure and element diffusion of welded joint were analyzed by SEM and EDS. The results show that the AZ31B/Cu can achieve good bonded joint composed of brazing seam zone and magnesium substrate grain boundary penetration zone at 500 °C for 20 min. The loading methods have great influence on the thickness of brazing seam zone, microstructure and α-Mg grain size of the welded joint. At intermittent gradient pressure, the brazing seam zone reaches the biggest width of 0.18 mm, and the microstructure of brazing seam zone is composed of Cu11Mg10Ni9, (α-Mg+Mg2Cu+Mg2Ni)eutectic structure and α-Mg. Under gradient pressure, the width of brazing seam zone reduces, and the microstructure of brazing seam zone is mainly dominated by (α-Mg+Mg2Cu+Mg2Ni)eutectic structure and Cu11Mg10Ni9 compounds closed magnesium matrix. When using constant pressure, the microstructure of joint is similar to that under intermittent gradient pressure, the brazing seam zone reaches the smallest width of 0.11 mm, and the size of α-Mg grains reduces.

  2. The Effect of SiC Particle Addition During FSW on Microstructure and Mechanical Properties of AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Abbasi, M.; Abdollahzadeh, A.; Bagheri, B.; Omidvar, H.

    2015-12-01

    Welding and joining of magnesium alloys exert a profound effect on magnesium application expansion, especially in ground and air transportations where large-size, complex components are required. Due to specific physical properties of magnesium, its welding requires great control. In general, the solid-state nature of friction stir welding (FSW) process has been found to produce a low concentration of defects. In the current research, specimens from AZ31 magnesium alloy were welded together using the friction stir process with previously inserted SiC powder particles in the nugget zone. In other words, during the FSW process, the pre-placed SiC particles were stirred throughout the nugget zone of the weld. The results indicated that proper values of rotation and translation speeds led to good appearance of weld zone and suitable distribution of SiC particles producing increased weld strength. The comparison of the microstructures and mechanical properties of FS-welded AZ31 with those of FS-welded one using pre-placed SiC particles showed that the addition of SiC particles decreased the grain size and increased the strength and the formability index.

  3. H2A.Z controls the stability and mobility of nucleosomes to regulate expression of the LH genes

    PubMed Central

    Rudnizky, Sergei; Bavly, Adaiah; Malik, Omri; Pnueli, Lilach; Melamed, Philippa; Kaplan, Ariel

    2016-01-01

    The structure and dynamics of promoter chromatin have a profound effect on the expression levels of genes. Yet, the contribution of DNA sequence, histone post-translational modifications, histone variant usage and other factors in shaping the architecture of chromatin, and the mechanisms by which this architecture modulates expression of specific genes are not yet completely understood. Here we use optical tweezers to study the roles that DNA sequence and the histone variant H2A.Z have in shaping the chromatin landscape at the promoters of two model genes, Cga and Lhb. Guided by MNase mapping of the promoters of these genes, we reconstitute nucleosomes that mimic those located near the transcriptional start site and immediately downstream (+1), and measure the forces required to disrupt these nucleosomes, and their mobility along the DNA sequence. Our results indicate that these genes are basally regulated by two distinct strategies, making use of H2A.Z to modulate separate phases of transcription, and highlight how DNA sequence, alternative histone variants and remodelling machinery act synergistically to modulate gene expression. PMID:27653784

  4. Fluoride ions as modifiers of the oxide layer produced by plasma electrolytic oxidation on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Kazanski, Barbara; Kossenko, Alexey; Zinigrad, Michael; Lugovskoy, Alex

    2013-12-01

    Plasma electrolytic oxidation (PEO) is a powerful technique allowing hardening and corrosion protection of valve metals due to formation of an oxide layer on the metal surface. PEO produces much thicker oxide layers as compared to anodizing, which is of critical importance for many technological applications. The present research investigated the influence of the fluoride ion concentration on the composition, structure and morphology of PEO layers on the magnesium alloy AZ91D. The obtained oxide layers were characterized with XRD, SEM, EDS and tested for corrosion resistance by linear sweep voltammetry in 3.5% NaCl medium. During this investigation it was found that KF addition produces significant changes in the structure and properties of the oxide layers. Fluorine was detected as an amorphous phase in the vicinity of the base metal for both alloys and plausible mechanism was suggested to explain these phenomena. Fluoride ions have pronounced catalytic activity and their presence considerably increases the thickness of the oxide layer. Depending on the process parameters, significant improvement of the corrosion stability of AZ91D alloy is achieved by the use of PEO.

  5. Grain size dependence of dynamic mechanical behavior of AZ31B magnesium alloy sheet under compressive shock loading

    SciTech Connect

    Asgari, H.; Odeshi, A.G.; Szpunar, J.A.; Zeng, L.J.; Olsson, E.

    2015-08-15

    The effects of grain size on the dynamic deformation behavior of rolled AZ31B alloy at high strain rates were investigated. Rolled AZ31B alloy samples with grain sizes of 6, 18 and 37 μm, were subjected to shock loading tests using Split Hopkinson Pressure Bar at room temperature and at a strain rate of 1100 s{sup −} {sup 1}. It was found that a double-peak basal texture formed in the shock loaded samples. The strength and ductility of the alloy under the high strain-rate compressive loading increased with decreasing grain size. However, twinning fraction and strain hardening rate were found to decrease with decreasing grain size. In addition, orientation imaging microscopy showed a higher contribution of double and contraction twins in the deformation process of the coarse-grained samples. Using transmission electron microscopy, pyramidal dislocations were detected in the shock loaded sample, proving the activation of pyramidal slip system under dynamic impact loading. - Highlights: • A double-peak basal texture developed in all shock loaded samples. • Both strength and ductility increased with decreasing grain size. • Twinning fraction and strain hardening rate decreased with decreasing grain size. • ‘g.b’ analysis confirmed the presence of dislocations in shock loaded alloy.

  6. Numerical assessment of the role of slip and twinning in magnesium alloy AZ31B during loading path reversal

    SciTech Connect

    Wang, Huamiao; Wu, Peidong; Wang, Jian

    2015-04-17

    Magnesium alloy AZ31B plastically deforms via twinning and slip. Corresponding to the unidirectional nature of twinning, the activity of twinning/detwinning is directly related to loading history and materials texture. Using the elastic viscoplastic self-consistent model implementing with the twinning and detwinning model (EVPSC–TDT), we revisited experimental data of AZ31B sheets under four different strain paths: (1) tension–compression–tension along rolling direction, (2) tension–compression–tension along transverse direction, (3) compression–tension–compression along rolling direction, and (4) compression–tension–compression along transverse direction, and identified the dominant deformation mechanisms with respect to the strain path. We captured plastic deformation behaviors observed in experiments and quantitatively interpreted experimental observations in terms of the activities of different deformation mechanisms and the evolution of texture. It is found that the in-plane pre-tension has slight effect on the subsequent deformation, and the pre-compression and the reverse tension after compression have significant effect on the subsequent deformation. The inelastic behavior under compressive unloading is found to be insignificant at a small strain level but pronounced at a large strain level. Lastly, such significant effect is mainly ascribed to the activity of twinning and detwinning.

  7. Numerical assessment of the role of slip and twinning in magnesium alloy AZ31B during loading path reversal

    DOE PAGES

    Wang, Huamiao; Wu, Peidong; Wang, Jian

    2015-04-17

    Magnesium alloy AZ31B plastically deforms via twinning and slip. Corresponding to the unidirectional nature of twinning, the activity of twinning/detwinning is directly related to loading history and materials texture. Using the elastic viscoplastic self-consistent model implementing with the twinning and detwinning model (EVPSC–TDT), we revisited experimental data of AZ31B sheets under four different strain paths: (1) tension–compression–tension along rolling direction, (2) tension–compression–tension along transverse direction, (3) compression–tension–compression along rolling direction, and (4) compression–tension–compression along transverse direction, and identified the dominant deformation mechanisms with respect to the strain path. We captured plastic deformation behaviors observed in experiments and quantitatively interpreted experimentalmore » observations in terms of the activities of different deformation mechanisms and the evolution of texture. It is found that the in-plane pre-tension has slight effect on the subsequent deformation, and the pre-compression and the reverse tension after compression have significant effect on the subsequent deformation. The inelastic behavior under compressive unloading is found to be insignificant at a small strain level but pronounced at a large strain level. Lastly, such significant effect is mainly ascribed to the activity of twinning and detwinning.« less

  8. Educating Cities in Latin America

    ERIC Educational Resources Information Center

    Messina, Graciela; Valdés-Cotera, Raúl

    2013-01-01

    This article considers the development of educating cities from a political perspective, illustrating in detail the diversity of organisations and individuals involved and the challenges they are facing. Bearing in mind that educating cities were established from the 1990s onwards in Europe and spread to other continents from there, the purpose of…

  9. De-Regulating the Cities

    ERIC Educational Resources Information Center

    DeMuth, Christopher C.

    1976-01-01

    A review essay focusing on two recent books, The Politics of Neglect: Urban Aid from Model Cities to Revenue Sharing, by Bernard J. Frieden and Marshall Kaplan (The MIT Press), and Between the Idea and the Reality: A Study in the Origin, Fate, and Legacy of the Model Cities Program, by Charles M. Haar (Little, Brown). (JM)

  10. Chicago, Illinois: The Windy City

    ERIC Educational Resources Information Center

    McIntosh, Phyllis

    2008-01-01

    Once famous mainly for stockyards and steel mills, Chicago now boasts more top-rated five-star restaurants than any other city in the United States and has been voted by various publications as one of the "Top 10 U.S. Destinations," one of the "Best Walking Cities" in the United States, and one of the "Ten Best Places to…

  11. CHED Events: Salt Lake City

    NASA Astrophysics Data System (ADS)

    Wink, Donald J.

    2009-03-01

    The Division of Chemical Education (CHED) Committee meetings planned for the Spring 2009 ACS Meeting in Salt Lake City will be in the Marriott City Center Hotel. Check the location of other CHED events, the CHED Social Event, the Undergraduate Program, Sci-Mix, etc. because many will be in the Salt Palace Convention Center.

  12. Modern Experience in City Combat

    DTIC Science & Technology

    1987-03-01

    reinforce the West Wall in the Aachen sector. A rapid thrust bypassing the city was no longer possible. Aachen, as the ancient capital of Charlemagne , had...old capital of the Vietnamese emperors and its most nota- ble feature was the walled citadel, or old city, lying north of the Perfume River. The

  13. Educating cities in Latin America

    NASA Astrophysics Data System (ADS)

    Messina, Graciela; Valdés-Cotera, Raúl

    2013-09-01

    This article considers the development of educating cities from a political perspective, illustrating in detail the diversity of organisations and individuals involved and the challenges they are facing. Bearing in mind that educating cities were established from the 1990s onwards in Europe and spread to other continents from there, the purpose of this article is to demonstrate how this proposal was adopted in Latin America. After discussing the basic aims of educating cities, the paper focuses on the Latin American experience, giving examples of existing projects within the educating cities initiative. The authors are particularly interested in the contrast between the political intentions of educating cities on the one hand and the social, economic, political and cultural world on the other hand. They observe that in this context there is a danger of the individual being forgotten, which contradicts the actual intention of the educating city concept. They also discuss the problem of who should carry out the realisation of educating cities and how the various stakeholders might coordinate their actions. Contemplating new directions at the end of their paper, the authors sum up a number of guidelines and offer recommendations for action in developing educating cities.

  14. New York City: Musically Speaking.

    ERIC Educational Resources Information Center

    Aiex, Nola Kortner

    New York City as a subject has fascinated generations of artists, writers, and musicians. However, the glamorous image of the city has changed over the years, and in the 1960s, popular music, in particular, began to reflect a utopia/dystopia dichotomy in relation to New York. During the past twenty years, six popular singer-songwriters who have…

  15. Broken Cities: Liberalism's Urban Legacy.

    ERIC Educational Resources Information Center

    Hayward, Steven

    1998-01-01

    Argues how the nation's inner-city population exodus and economic decay is a result of modern liberal social policy. Three failures of liberalism regarding inner cities are examined: the failure to nurture the sources of economic growth; the failure to understand urban neighborhoods; and the failure to appreciate the importance of a strong moral…

  16. Knowledge Infrastructures for Solar Cities

    ERIC Educational Resources Information Center

    Vanderburg, Willem H.

    2006-01-01

    The evolution of contemporary cities into solar cities will be affected by the decisions of countless specialists according to an established intellectual and professional division of labor. These specialists belong to groups responsible for advancing and applying a body of knowledge, and jointly, these bodies of knowledge make up a knowledge…

  17. Archaeoastronomy and Calendar Cities

    NASA Astrophysics Data System (ADS)

    Campion, Nicholas

    2016-02-01

    The use of astronomy for collective purposes, both religious and political, is apparent in the earliest astronomical records, from the evidence for Palaeolithic lunar calendars to megalithic monuments and Mesopotamian celestial-omen reports. This paper will consider the application of the heavens to the organisation of the ‘Cosmic State’, the human polity modelled on the assumption of a close relationship between society on the one hand and planetary and stellar patterns on the other. I will also examine the foundation of Baghdad within the tradition of celestial town planning and argue that the city may be seen as a ‘talisman’, designed to connect heaven to Earth and ensure peace, stability and political success by harmonising time and space.

  18. 77 FR 55787 - Proposed Flood Elevation Determinations for the City of Carson City, NV

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-11

    ... City of Carson City, NV AGENCY: Federal Emergency Management Agency, DHS. ACTION: Proposed rule... concerning proposed flood elevation determinations for the City of Carson City, Nevada. DATES: This... flood elevation determinations along one or more flooding sources in the City of Carson City,...

  19. 49 CFR 372.221 - Twin Cities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....-Tenn. (3) Davenport, Iowa, and Rock Island and Moline, Ill. (4) Delmar, Del-Md. (5) Harrison, Ohio-West Harrison, Ind. (6) Junction City, Ark.-La. (7) Kansas City, Mo.-Kansas City, Kans. (8) Minneapolis-St....

  20. Our cities, our future: cities, interagency cooperation, and sustainable development.

    PubMed

    Eigen, J

    1995-11-01

    Cities are the most important sites of socioeconomic development, offering significant economies of scale in providing jobs, housing and services, and are important centers of productivity and social advancement. Cities also absorb two thirds of developing countries' population growth; the developing world's cities will absorb more than 75% of total world population increase during 1990-2000. Urban environmental problems, however, seriously threaten the full realization of cities' potential socioeconomic contributions. Environmental degradation has many costs, leads to significant inefficiencies in the use of local resources, compounds inequities, and threatens the sustainability of development achievements. Urban development and environmental management therefore cannot be considered separately. Actions in the city affect the environment, and the environment in turn affects the city. Agenda 21, a global agenda for cooperation which emerged from the 1992 UN Conference on Environment and Development emphasizing cross-sectoral coordination, the decentralization of decision making, and broad-based participatory approaches to development management, and the Sustainable Cities Program are discussed.