WorldWideScience

Sample records for estefade az mohasebe

  1. Investigation on the Mechanical Properties of Mg-Al Alloys (AZ41 and AZ51 and Its Composites

    Directory of Open Access Journals (Sweden)

    Manoj Gupta

    2012-08-01

    Full Text Available In the present study, AZ41 and AZ51 alloys were fabricated using disintegrated melt deposition technique followed by hot extrusion. AZ41/Yttria and AZ51/Yttria composites were prepared using 0.6 wt% yttria nano particles in the alloys using the same fabrication technique. From the tensile test results, both strengths (yield and tensile and ductility were improved in AZ51 when compared to AZ41. In comparison with its alloy counterparts, the yield and tensile strengths were enhanced while maintaining the same ductility in AZ41/Yttria composite, but comparable strengths with decreased ductility were observed in AZ51/Yttria composite. Under compressive loading, an improvement in strengths with similar ductility was observed in AZ51 when compared to AZ41. The best combination of strengths and ductility was observed in AZ51/Yttria composites from compression test results. The obtained mechanical properties are correlated with the microstructure observations.

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

    Directory of Open Access Journals (Sweden)

    Helbing Caren C

    2009-12-01

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

  3. Tank 241-AZ-101 tank characterization plan

    Energy Technology Data Exchange (ETDEWEB)

    Schreiber, R.D.

    1995-02-06

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Joining of AZ31 and AZ91 Mg alloys by friction stir welding

    Directory of Open Access Journals (Sweden)

    B. Ratna Sunil

    2015-12-01

    Full Text Available Two dissimilar magnesium (Mg alloy sheets, one with low aluminium (AZ31 and another with high aluminium (AZ91 content, were successfully joined by friction stir welding (FSW. The effect of process parameters on the formation of hot cracks was investigated. A sound metallurgical joint was obtained at optimized process parameters (1400 rpm with 25 mm/min feed which contained fine grains and distributed β (Mg17Al12 phase within the nugget zone. An increasing trend in the hardness measurements has also confirmed more amount of dissolution of aluminium within the nugget zone. A sharp interface between nugget zone and thermo mechanical affected zone (TMAZ was clearly noticed at the AZ31 Mg alloy side (advancing but not on the AZ91 Mg alloy side (retreating. From the results it can be concluded that FSW can be effectively used to join dissimilar metals, particularly difficult to process metals such as Mg alloys, and hot cracking can be completely eliminated by choosing appropriate process parameters to achieve sound joint.

  6. Grain refinement of AZ31 magnesium alloy by electromagnetic ...

    Indian Academy of Sciences (India)

    The effects of electromagnetic stirring and Al4C3 grain refiner on the grain refinement of semicontinuously cast AZ31 magnesium alloy were discussed in this investigation. The results indicate that electromagnetic stirring has an effective refining effect on the grain size of AZ31 magnesium alloy under the effect of Al4C3 ...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. UV Energy Distribution of AZ Cassiopeiae

    Directory of Open Access Journals (Sweden)

    Young Woon Kang

    1994-06-01

    Full Text Available The IUE low dispersion spectra of AZ Cas have been analyzed for line identifications and energy distribution in ultraviolet region. Highly ionized atoms, Si IV and C IV are identified. We could infer a temperature range of the B star between 15,000K and 20,000K. The energy density distribution shows a hump between IUE short wavelength and long wavelength regions. Photometric and spectroscopic elements were revised based on the Florkowisk photoelectric observations and collected radial velocities. The temperature of both stars were reduced as 16,000K and 3,800K. The radii of both stars are 10 R⨀ and 320 R⨀. The eccentricity and longitude of periastron are 0.61 and 10.5°, respectively.

  9. Facebook Marketing - Fra A-Z

    DEFF Research Database (Denmark)

    Mortensen, Thomas Bøtker

    2009-01-01

    Facebook Marketing – Leverage Social Media to Grow Your Business af Steven Holzner er Facebook Marketing fra A-Z, som kan anbefales til virksomheder, som overvejer at bevæge sig ud i cyber space og afprøve mulighederne for at markedsføre sig dér. Bogen beskriver på hvilke væsentlige punkter...... marketing på Facebook adskiller sig fra traditionel marketing, og gennemgår trin for trin de fundamentale ting, som man skal vide for, at virksomheden kan agere med den tilsigtede effekt i et socialt netværk som Facebook. Og eftersom 34 % af den danske befolkning i dag er hoppet med på Facebook vognen og...... har oprettet en profil på Facebook, er potentialet åbenlyst....

  10. A comparative corrosion behavior of Mg, AZ31 and AZ91 alloys in 3.5% NaCl solution

    Directory of Open Access Journals (Sweden)

    I.B. Singh

    2015-06-01

    Full Text Available The corrosion behavior of Mg, AZ31 and AZ91 has been evaluated in 3.5% NaCl solution using weight loss, electrochemical polarization and impedance measurements. Corrosion rate derived from the weight losses demonstrated the occurrence of steeply fast corrosion reaction on AZ91 alloy after three hours of immersion, indicating the start of galvanic corrosion. An increase of corrosion rate with immersion time was also observed for AZ31 but with lesser extent than AZ91 alloy. Whereas Mg metals showed a decrease of corrosion rate with immersion time, suggesting the formation of a protective layer on their surfaces. In contrast, the corrosion current density (Icorr derived from the Tafel plots, exhibited their corrosion resistances in order of Mg > AZ91 > AZ31. Electrochemical charge transfer resistance (Rct and double layer capacitance measured by electrochemical impedance spectroscopy (EIS, are well in accordance with the measured Icorr. EIS measurements with time and microstructural examination of the corroded and uncorroded samples are helpful in elucidation of results measured by electrochemical polarization.

  11. 75 FR 81190 - Television Broadcasting Services; Yuma, AZ

    Science.gov (United States)

    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 Arizona...

  12. Recommendation Report: EJournals/EBooks A-Z Management System

    KAUST Repository

    Ramli, Rindra M.

    2014-01-01

    This is a recommendation report for KAUST Library on the Ejournals / EBooks AZ Management systems project. It briefly described the issues faced by the ERM Team, project plan overview and the project findings as well as the recommendation(s).

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. AZ91C magnesium alloy modified by Cd

    DEFF Research Database (Denmark)

    Shabadi, R.; Ambat, Rajan; Dwarakadasa, E.S.

    2014-01-01

    precipitates to discontinuous β-phase upon the addition of Cd was observed. A marginal increment in mechanical properties was observed. General corrosion behaviour was followed with weight loss measurements, potentiostatic polarisation studies and surface studies in 3.5% sodium chloride solution and 3.......5% sodium chloride with 2% potassium dichromate solution. Cd addition deteriorated the corrosion behaviour of AZ91C. This behaviour was attributed to the formation of chunks of β-phase upon the addition of Cd. AZ91C with refined β-phase distribution, performed rather better in the NaCl solutions....

  15. Thermal analytical investigations of the magnesium alloy AZ91

    Directory of Open Access Journals (Sweden)

    K.N. Braszczyńska - Malik

    2007-04-01

    Full Text Available The results of thermal derivative analysis (TDA, differential scanning calorimetric (DSC measurements and microstructure investigations of commercial AZ91 magnesium alloy are presented. The performed examinations allowed to determine the microstructure after solidification process and also precipitation process during continuous heating of supersaturated solid solution. The α-phase and α+γ semi-divorced eutectic were observed in as-cast material, whereas both discontinuous and continuous precipitates of γ phase were revealed after heating supersaturated AZ91 alloy.

  16. Data of evolutionary structure change: 1AZ5A-2IEOA [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1AZ5A-2IEOA 1AZ5 2IEO A A PQFHLWKRPVVTAHIEGQPVEVLLDTGADDSIVTGIELG...PHYTPKIV----GFINTKEYKNVEVEVLGKRIKGTIMTGDTPINIFGRNLLTALGMSLNF PQITLWKRPLVTIKIGGQLKEALLDTGADDTVIE...EMSLPGRWKPKMIGGIGGFIKVRQYDQIIIEIAGHKAIGTVLVGPTPVNVIGRNLLTQIGATLNF EEEEE EEEEEEEE EE EEEEE---- ...e>THR CA 318 2IEO A 2IE

  17. 75 FR 76293 - Radio Broadcasting Services; Peach Springs, AZ

    Science.gov (United States)

    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 citation...

  18. Grain refinement of AZ31 magnesium alloy by electromagnetic ...

    Indian Academy of Sciences (India)

    cess are discussed; furthermore, effect of holding time on the refinement of AZ31 magnesium alloy was investigated. 2. Experimental. Al4C3 grain refiner was synthesized by powder metallurgy. The raw materials included aluminum powder (99·8% pure,. 50 μm in diameter), graphite powder (99·6% pure, 50 μm in diameter) ...

  19. Bernal Díaz del Castillo en Guatemala

    Directory of Open Access Journals (Sweden)

    Julio César Pinto Soria

    2014-10-01

    Full Text Available Este artículo se ocupa de la hasta ahora poco investigada vida de Bernal Díaz del Castillo en Guatemala, país donde escribe la Historia verdadera de la conquista de la Nueva España en la segunda mitad del siglo xvi. La primera parte analiza la crónica, su importancia y principales ediciones críticas. La parte central se dedica a la relación de Bernal Díaz con la historia de Guatemala. Se aborda su comportamiento como encomendero, su vínculo con los indígenas y con el régimen colonial guatemalteco. La última parte profundiza en el cronista, las circunstancias y sus motivos para escribir la crónica, y en el lugar de esta en el imaginario cultural y político de Guatemala. En una posdata se hace referencia crítica a la obra de Christian Duverger (2012 que cuestiona a Bernal Díaz como autor de la crónica. Abstract  This article deals with the hitherto scarcely researched life of Bernal Díaz del Castillo in Guatemala, country where he wrote the True History of the Conquest of New Spain in the second half of the 16th century. The first chapter examines the chronicle, its importance and main critical editions. The Bernal Diaz’s relationship with the history of Guatemala is addressed in the main chapter, exploring his behavior as an encomendero, his link with the indigenous people and the Guatemalan colonial regime. The last chapter delves in the chronicler, the circumstances and his motivation for writing the chronicle, as well as its place in the cultural and political imaginary of Guatemala. As a PostScript, a critical reference to the work of Christian Duverger (2012, who questions Bernal Díaz as the author of the chronicle, is presented.

  20. Very high cycle fatigue behaviour of as-extruded AZ31, AZ80, and ZK60 magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Novy, Frantisek; Skorik, Viktor [Zilina Univ. (Slovakia). Dept. of Materials Engineering; Janecek, Milos [Charles Univ., Prague (Czech Republic). Dept. of Physics of Materials; Mueller, Julia; Wagner, Lothar [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. of Materials Science and Technology

    2009-03-15

    The very high cycle fatigue properties of extruded AZ31, AZ80, and ZK60 magnesium alloys were investigated. Fatigue tests were performed at ultrasonic cyclic frequency and at a load ratio of R = -1 at ambient temperature using smooth electropolished specimens. Fatigue failures were observed at lifetimes above 10{sup 9} cycles. The fatigue life was found to increase with decreasing stress amplitude. The fracture surfaces and fracture profiles of selected specimens cycled until failure were examined. The purpose of the study was to determine the role of the microstructure on the fatigue crack nucleation and growth. Furthermore, the fatigue properties were discussed on the basis of microstructure and the presence of inclusions which are known as crack initiation sites. In AZ31 and AZ80 alloys only surface-induced fatigue cracks were observed. On the other hand, in the ZK60 alloy both surface- and interior-induced fatigue cracks were observed. Both mechanisms operate in the ZK60 also at a lifetime of around 10{sup 1}0 cycles. Interior-induced fatigue cracks were accompanied by clear fish-eye marks on the fracture surfaces of the ZK60 alloy. (orig.)

  1. The Corrosion Protection of Magnesium Alloy AZ31B

    Science.gov (United States)

    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.

  2. Histone variant H2A.Z.2 mediates proliferation and drug sensitivity of malignant melanoma

    Science.gov (United States)

    Vardabasso, Chiara; Gaspar-Maia, Alexandre; Hasson, Dan; Pünzeler, Sebastian; Valle-Garcia, David; Straub, Tobias; Keilhauer, Eva C.; Strub, Thomas; Dong, Joanna; Panda, Taniya; Chung, Chi-Yeh; Yao, Jonathan L.; Singh, Rajendra; Segura, Miguel F.; Fontanals-Cirera, Barbara; Verma, Amit; Mann, Matthias; Hernando, Eva; Hake, Sandra B.; Bernstein, Emily

    2015-01-01

    SUMMARY Histone variants are emerging as key regulatory molecules in cancer. Here we report a novel role for the H2A.Z isoform H2A.Z.2 as a driver of malignant melanoma. H2A.Z.2 is highly expressed in metastatic melanoma, correlates with decreased patient survival, and is required for cellular proliferation. Our integrated genomic analyses reveal that H2A.Z.2 controls the transcriptional output of E2F target genes in melanoma cells. These genes are highly expressed and display a distinct signature of H2A.Z occupancy. We identify BRD2 as an H2A.Z interacting protein, whose levels are also elevated in melanoma. We further demonstrate that H2A.Z.2 regulated genes are bound by BRD2 and E2F1 in a H2A.Z.2-dependent manner. Importantly, H2A.Z.2 deficiency sensitizes melanoma cells to chemotherapy and targeted therapies. Collectively, our findings implicate H2A.Z.2 as a mediator of cell proliferation and drug sensitivity in malignant melanoma, holding translational potential for novel therapeutic strategies. PMID:26051178

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

    Energy Technology Data Exchange (ETDEWEB)

    Nishibuchi, Ikuno [Department of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima (Japan); Department of Radiation Oncology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima (Japan); Department of Radiation Oncology, Hiroshima Prefectural Hospital, Hiroshima (Japan); Suzuki, Hidekazu; Kinomura, Aiko; Sun, Jiying; Liu, Ning-Ang [Department of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima (Japan); Horikoshi, Yasunori [Department of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima (Japan); Research Center for Mathematics of Chromatin Live Dynamics, Hiroshima University, Hiroshima (Japan); Shima, Hiroki [Department of Biochemistry, Graduate School of Medical Sciences, Tohoku University, Sendai (Japan); Kusakabe, Masayuki; Harata, Masahiko [Laboratory of Molecular Biology, Graduate School of Agricultural Science, Tohoku University, Sendai (Japan); Fukagawa, Tatsuo [Department of Molecular Genetics, National Institute of Genetics and The Graduate University for Advanced Studies, Mishima (Japan); Ikura, Tsuyoshi [Laboratory of Chromatin Regulatory Network, Department of Mutagenesis, Radiation Biology Center, Kyoto University, Kyoto (Japan); Ishida, Takafumi [Department of Cardiovascular Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima (Japan); Nagata, Yasushi [Department of Radiation Oncology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima (Japan); Tashiro, Satoshi, E-mail: ktashiro@hiroshima-u.ac.jp [Department of Cellular Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima (Japan); Research Center for Mathematics of Chromatin Live Dynamics, Hiroshima University, Hiroshima (Japan)

    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

  4. Enhancing Microstructure and Mechanical Properties of AZ31-MWCNT Nanocomposites through Mechanical Alloying

    Directory of Open Access Journals (Sweden)

    J. Jayakumar

    2013-01-01

    Full Text Available Multiwall carbon nanotubes (MWCNTs reinforced Mg alloy AZ31 nanocomposites were fabricated by mechanical alloying and powder metallurgy technique. The reinforcement material MWCNTs were blended in three weight fractions (0.33%, 0.66%, and 1% with the matrix material AZ31 (Al-3%, zinc-1% rest Mg and blended through mechanical alloying using a high energy planetary ball mill. Specimens of monolithic AZ31 and AZ31-MWCNT composites were fabricated through powder metallurgy technique. The microstructure, density, hardness, porosity, ductility, and tensile properties of monolithic AZ31 and AZ31-MWCNT nano composites were characterized and compared. The characterization reveals significant reduction in CNT (carbon nanoTube agglomeration and enhancement in microstructure and mechanical properties due to mechanical alloying through ball milling.

  5. 241-AZ Tank Farm Construction Extent of Condition Review for Tank Integrity

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Microstructural Characteristics and Mechanical Properties of 2205/AZ31B Laminates Fabricated by Explosive Welding

    Directory of Open Access Journals (Sweden)

    Yan Li

    2017-04-01

    Full Text Available A bimetal composite of 2205 duplex stainless steel and AZ31B magnesium alloy was cladded successfully through the method of explosive welding. The microstructural characteristics and mechanical properties of 2205/AZ31B bimetal composite are discussed. The interface of 2205/AZ31B bimetallic composite was a less regular wavy morphology with locally melted pockets. Adiabatic shear bands occurred only in the AZ31B side near explosive welding interface. The microstructure observed with EBSD showed a strong refinement near the interface zones. Line scan confirmed that the interface had a short element diffusion zone which would contribute to the metallurgical bonding between 2205 duplex stainless steel and AZ31B magnesium alloy. The value of micro-hardness near the bonding interface of composite plate increased because of work hardening and grain refinement. The tensile shear strength of bonding interface of 2205/AZ31B composite was 105.63 MPa. Tensile strength of 2205/AZ31B composite material was higher than the base AZ31B. There were two abrupt drops in stress in the stress–strain curves of the 2205/AZ31B composite materials.

  7. Fabrication of bimodal size SiCp reinforced AZ31B magnesium matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Shen, M.J., E-mail: smjiekaka@163.com [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, X.J., E-mail: xjwang@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhang, M.F. [Hisense Ronshen Co., Ltd., Yingkou 115000 (China); Hu, X.S.; Zheng, M.Y.; Wu, K. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2014-04-01

    Bimodal sized (Micro-particles: m and Nano-particles: n) SiC particulates (SiCp) reinforced magnesium matrix composites with different volume fractions of micro-particles (1n+4p, 1n+9p and 1n+14p) were prepared by a semisolid stirring assisted ultrasonic vibration method. Both the as-cast SiCp/AZ31B composites and the AZ31B alloy were extruded at 350 °C with the extrusion ratio of 12:1 at a constant ram speed of 15 mm/s. The microstructure investigation was carried out by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The results show that the distribution of bimodal size SiCp and the mechanical properties of the AZ31B alloy were significantly improved after hot extrusion. When the volume fraction of nano SiCp is 1 vol%, both the yield strength and ultimate tensile strength of the AZ31B/SiC/1n+14p composite are stronger than that of the AZ31B/SiC/1n+4p and AZ31B/SiC/1n+9p composites, while the elongation to fracture was decreased comparing with the AZ31B/SiC/1n+4p and AZ31B/SiC/1n+9p composites.

  8. Data of evolutionary structure change: 1B99C-2AZ1D [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available GSDS--VESAN >E --HHHHH> ATOM 316...>D 2AZ1D HGSDHEDEGANE >E HHH...pdbID>1B99 C 1B99C EELLT-EVKPN ...> - > ATOM 3319 CA GLU C 141 17.330 5.755...DChain>2AZ1D DELVDWDRDAS re>GG EEGGHcture

  9. Data of evolutionary structure change: 1JH5I-2AZ5A [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available ID> I 1JH5I LYTDK-----TYAMG ...>EE -----EEEEE> ATOM 9622 CA LEU I 59 -64.244 97.997...ain> 2AZ5A LFKGQGCPSTHVLLT >EEEE EE... 2AZ5A IAVSY----QTKVN ...>E ---- EEE > ATOM 526 CA ILE A 83 -19.844 60.232 51

  10. Genome Sequence of the Acidophilic Bacterium Acidocella sp. Strain MX-AZ02

    DEFF Research Database (Denmark)

    Servín-Garcidueñas, Luis E.; Garrett, Roger A.; Amils, Ricardo

    2013-01-01

    Here, we report the draft genome sequence of Acidocella sp. strain MX-AZ02, an acidophilic and heterotrophic alphaproteobacterium isolated from a geothermal lake in western Mexico.......Here, we report the draft genome sequence of Acidocella sp. strain MX-AZ02, an acidophilic and heterotrophic alphaproteobacterium isolated from a geothermal lake in western Mexico....

  11. Dictionary of engines. The internal combustion engine from A-Z; Lexikon Motorentechnik. Der Verbrennungsmotor von A-Z

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, F. (ed.); Basshuysen, R. van

    2004-04-01

    This dictionary describes current engine technology and gives an outlook to the future. Cross-references, broader and narrower terms ensure optimal user guidance. Entries do not stand alone but provide content-oriented information. About 4,500 terms are included from A-Z, providing an outline of subjects like exhaust systems, acoustics, supercharging, combustion chamber, injection systems, control, flame propagation, mixing, catalytic converters, pistons, fuels, cooling, crank casing, stratified charging, lambda control, camshaft, oil, particulate filters, sensors/actuators, pollutants, valves, combustion processes, efficiency, ignition, cylinder head. The dictionary is for development engineers in the motor car industry, in component and system development in the supply industry, university teachers and students, foremen in motor car repair shops, etc. (orig.) [German] Das Lexikon Motorentechnik ist ein Nachschlagewerk, das die aktuelle Motorentechnik umfassend beschreibt und Ausblicke in der Zukunft ermoeglicht. Das ausgefeilte System aus Querverweisen fuehrt alle Unterbegriffe zum Hauptbegriff und ermoeglicht so eine optimale Benutzerfuehrung. Dadurch stehen die Stichwoerter nicht isoliert, sondern es werden inhaltlich zusammenhaengende Betrachtungen moeglich. Der Inhalt umfasst 4 500 Begriffe von A-Z wie z.B.: Abgastechnik, Akustik, Aufladung, Brennraum, Einspritzsysteme, Elektronische Motorsteuerung, Flammenausbreitung, Gemischbildung, Katalysator, Kolben, Kraftstoff, Kuehlung, Kurbelgehaeuse, Kurbeltrieb, Ladungswechsel, Lambda-Regelung, Nockenwelle, Oel, Partikelfilter, Sensoren/Aktuatoren, Schadstoffe, Ventiltrieb, Verbrennungsverfahren, Wirkungsgrad, Zuendung, Zylinderkopf. Die Zielgruppen waeren Ingenieure in Motoren- und Fahrzeugentwicklung der Automobilindustrie, Ingenieure in der Komponenten- und Systementwicklung der Zuliefererindustrie, Professoren und Studenten an Hochschulen mit Schwerpunkt Kraftfahrzeugtechnik, Meister in Kfz-Werkstaetten. (orig.)

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

    Directory of Open Access Journals (Sweden)

    Jian Zou

    2017-01-01

    Full Text Available 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.

  13. On the deformation twinning of Mg AZ31B

    DEFF Research Database (Denmark)

    Abdolvand, Hamidreza; Majkut, Marta; Oddershede, Jette

    2015-01-01

    Crystals with a hexagonal close-packed (HCP) structure are inherently anisotropic, and have a limited number of independent slip systems, which leads to strong deformation textures and reduced formability in polycrystalline products. Tension along the c-axis of the crystal ideally activates...... extension twinning as a deformation mode due to the lack of easy-slip systems. In this work, experiments were devised to study extension twinning in a polycrystalline Mg alloy AZ31B with a strong basal rolling texture by tensile deformation parallel to the plate normal. Three-dimensional synchrotron X......-ray diffraction (3DXRD) was used to map the center-of-mass positions, volumes, orientations, elastic strains, and stress tensors of over 1400 grains in-situ up to a true strain of 1.4%. More than 700 tensile twins were observed to form in the mapped volume under deformation. The measured center-of-mass positions...

  14. Electrochemical properties of fine-grained AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hadzima, Branislav; Bukovina, Michal [Univ. of Zilina (Slovakia). Dept. of Materials Engineering; Janecek, Milos; Kral, Robert [Charles Univ., Dept. of Physics of Materials, Prague (Czech Republic)

    2009-09-15

    The influence of equal channel angular pressing (ECAP) on the microstructure changes of magnesium alloy AZ31 was investigated. The microstructure changes were correlated with electrochemical characteristics of the surface. Eight passes of ECAP resulted in significant grain refinement (factor 100) of the initial squeeze-cast (SC) alloy. The influence of microstructure changes on electrochemical properties of the surface was evaluated using electrochemical impedance spectroscopy. The variation of electrochemical characteristics of the surface of the SC and ECAP alloy was determined after 3 and 7-day exposure in the corrosion solution of 0.1 M NaCl. The fine-grained deformed structure after ECAP was found to have significantly higher charge transfer resistance as compared to the squeeze-cast material. (orig.)

  15. High speed cutting of AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Liwei Lu

    2016-06-01

    Full Text Available Using LBR-370 numerical control lathe, high speed cutting was applied to AZ31 magnesium alloy. The influence of cutting parameters on microstructure, surface roughness and machining hardening were investigated by using the methods of single factor and orthogonal experiment. The results show that the cutting parameters have an important effect on microstructure, surface roughness and machine hardening. The depth of stress layer, roughness and hardening present a declining tendency with the increase of the cutting speed and also increase with the augment of the cutting depth and feed rate. Moreover, we established a prediction model of the roughness, which has an important guidance on actual machining process of magnesium alloy.

  16. H2A.Z: view from the top.

    Science.gov (United States)

    Zlatanova, Jordanka; Thakar, Amit

    2008-02-01

    For a couple of decades the chromatin field has endured undeserved neglect. Indeed, what could be so exciting about a monotonous repeating structure whose purpose in life was to package DNA? Chromatin glamour is triumphantly back, due to the realization that chromatin is a major player in the regulation of gene expression and other nuclear processes that occur on the DNA template. The dynamics of the structure that regulates transcription is itself regulated by a variety of complex processes, including histone postsynthetic modifications, chromatin remodeling, and the use of nonallelic histone variants. This review is an attempt to understand the mechanisms of action of the evolutionarily conserved variant H2A.Z, a player with a variety of seemingly unrelated, even contrary, functions. This attempt was prompted by the recent avalanche of genome-wide studies that provide insights that were unthinkable until very recently.

  17. Resúmen Ejecutivo Caña de Azúcar

    OpenAIRE

    Ministerio de Agricultura y Riego

    2010-01-01

    El cultivo de caña de azúcar en el Perú, es de gran potencial de producción, principalmente por las condiciones óptimas de clima y suelo existentes, que ayudan a tener rendimientos muy buenos alrededor 120 toneladas por hectárea, convirtiéndose en un factor competitivo importante, de este cultivo se pueden extraer productos como el guarapo, azúcar rubia artesanal, chancaca y otros. La producción de caña de azúcar no tiene una estacionalidad definida por tanto la siembra y la cosecha se rea...

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

    Science.gov (United States)

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

    2014-04-24

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

  19. EnviroAtlas - Phoenix, AZ - Meter-Scale Urban Land Cover (MULC) Data (2010)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The EnviroAtlas Phoenix, AZ Meter-Scale Urban Land Cover (MULC) data and map were generated from USDA NAIP (National Agricultural Imagery Program) four band (red,...

  20. EnviroAtlas - Phoenix, AZ- One Meter Resolution Urban Land Cover Data (2010) Web Service

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas web service supports research and online mapping activities related to EnviroAtlas (https://www.epa.gov/enviroatlas). The EnviroAtlas Phoenix, AZ...

  1. Influence of process temperature on AZ91 matrix microstructure of composites with aluminosilicate glass cenospheres

    Directory of Open Access Journals (Sweden)

    J. Kamieniak

    2011-07-01

    Full Text Available AZ91 magnesium alloy matrix composites with aluminosilicate glass cenospheres were fabricated successfully by the pressure infiltration method. Different parameters of the fabrication process, such as temperature of the mould and temperature of cenospheres were used. Influence of the temperature variation of particular parameters on the microstructure has been investigated. The microstructure of AZ91 magnesium alloy and fabricated composites have been investigated by light microscopy (LM and scanning electron microscopy (SEM. The results revealed that AZ91 magnesium alloy consists of -Mg matrix and eutectic -Mg17Al12 and a small amount of discontinuous precipitates of  phase. The microstructure of matrix AZ91 in fabricated composites is characterized also by the presence of -Mg matrix and eutectic -Mg17Al12. However, in the composite fabricated byusingthe mould heated to 500 °C more discontinuous precipitates of  phase were observed.

  2. Effect of cenospheres addition on microstructure and properties of AZ91D alloy

    National Research Council Canada - National Science Library

    Zhi-qiu Huang Si-rong Yu Ming Hu Ying-chun Shi Liu-yan Li Guo-yan Bo

    2015-01-01

    The cenospheres/AZ91D composites were fabricated by melt stir method. The phases, microstructure and tensile fracture morphology of the composites were analyzed using XRD, Olympus metallurgical microscopy and SEM methods...

  3. EnviroAtlas - Phoenix, AZ - BenMAP Results by Block Group

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset demonstrates the effect of changes in pollution concentration on local populations in 2,434 block groups in Phoenix, AZ. The US EPA's...

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

    Science.gov (United States)

    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.

  5. 75 FR 49526 - Freescale Semiconductor, Inc., Technical Information Center, Tempe, AZ; Freescale Semiconductor...

    Science.gov (United States)

    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... to Apply for Worker Adjustment Assistance on October 1, 2009, applicable to workers of Freescale...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Electropolymerisation of Aniline on AZ91 Magnesium Alloy: The Effect of Coating Electrolyte Corrosiveness

    OpenAIRE

    Asif Baloch; M. Bobby Kannan

    2017-01-01

    In this study, polyaniline was coated on AZ91 magnesium alloy using an electropolymerisation technique, and the effect of corrosiveness of the coating electrolytes on the polymerisation and the coating performance were evaluated. Two electrolytes, i.e., aniline + sodium salicylate (PASS) and aniline + potassium hydroxide (PAPH), with different corrosiveness, were used for polyaniline coating on AZ91 magnesium alloy. Potentiodynamic polarisation results suggested that salicylic acid (C7H5NaO3)...

  8. Influence of process temperature on AZ91 matrix microstructure of composites with aluminosilicate glass cenospheres

    OpenAIRE

    J. Kamieniak; A. Żydek; K.N. Braszczyńska-Malik

    2011-01-01

    AZ91 magnesium alloy matrix composites with aluminosilicate glass cenospheres were fabricated successfully by the pressure infiltration method. Different parameters of the fabrication process, such as temperature of the mould and temperature of cenospheres were used. Influence of the temperature variation of particular parameters on the microstructure has been investigated. The microstructure of AZ91 magnesium alloy and fabricated composites have been investigated by light microscopy (LM) and...

  9. The Spectroscopic Studies of the Long Period Eclipsing Binary AZ CAS

    Directory of Open Access Journals (Sweden)

    Mun-Suk Chun

    1994-06-01

    Full Text Available Spectroscopic observations of the long period eclipsing binary AZ Cas were made using 122cm telescope/Image Tube. From the relatively sharp and strong spectral FeI lines we can calculate the mean radial velocity as -39.7 km/sec. The estimated equivalent widths of some atomic lines are well fitted to the phase of the AZ Cas.

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

    Science.gov (United States)

    Puopolo, Gerardo; Giovannini, Oscar; Pertot, Ilaria

    2014-01-01

    The bacterial genus Lysobacter represents a still underdeveloped source of biocontrol agents able to protect plants against pathogenic oomycetes. In this work the L. capsici strain AZ78 was evaluated with regard to the biological control of Plasmopara viticola, the causal agent of grapevine downy mildew. L. capsici AZ78 is able to resist copper ions and its resistance to this metal is probably due to the presence of genes coding for copper oxidase (copA) and copper exporting PIB-type ATPases (ctpA). The presence of both genes was also detected in other members of the Lysobacter genus. Resistance to copper allowed L. capsici AZ78 to be combined with a low-dose of a copper-based fungicide, leading to more effective control of grapevine downy mildew. Notably, prophylactic application of L. capsici AZ78 alone to grapevine leaves reduced downy mildew disease to the same degree as a copper-based fungicide. Furthermore, L. capsici AZ78 persists in the phyllosphere of grapevine plants and tolerates environmental stresses such as starvation, freezing, mild heat shock and UV light irradiation. These traits suggest that L. capsici AZ78 could be a suitable candidate for developing a new biofungicide to be used in combination with copper to control grapevine downy mildew. Copyright © 2013 Elsevier GmbH. All rights reserved.

  11. Electrochemical corrosion behavior of AZ91D alloy in ethylene glycol

    Energy Technology Data Exchange (ETDEWEB)

    Fekry, A.M. [Chemistry Department, Faculty of Science, Cairo University, Giza 12613 (Egypt)], E-mail: hham4@hotmail.com; Fatayerji, M.Z. [Chemistry Department, Faculty of Science, Cairo University, Giza 12613 (Egypt)

    2009-11-01

    The effect of concentration on the corrosion behavior of Mg-based alloy AZ91D was investigated in ethylene glycol-water solutions using electrochemical techniques i.e. potentiodynamic polarization, electrochemical impedance measurements (EIS) and surface examination via scanning electron microscope (SEM) technique. This can provide a basis for developing new coolants for magnesium alloy engine blocks. Corrosion behavior of AZ91D alloy by coolant is important in the automotive industry. It was found that the corrosion rate of AZ91D alloy decreased with increasing concentration of ethylene glycol. For AZ91D alloy in chloride >0.05 M or fluoride <0.05 M containing 30% ethylene glycol solution, they are more corrosive than the blank (30% ethylene glycol-70% water). However, at concentrations <0.05 for chloride or >0.05 M for fluoride containing ethylene glycol solution, some inhibition effect has been observed. The corrosion of AZ91D alloy in the blank can be effectively inhibited by addition of 0.05 mM paracetamol that reacts with AZ91D alloy and forms a protective film on the surface at this concentration as confirmed by surface examination.

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

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

    Science.gov (United States)

    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.

  14. CYCLIC FATIGUE RESISTANCE OF AZ91 MAGNESIUM ALLOY

    Directory of Open Access Journals (Sweden)

    Aneta Němcová

    2009-11-01

    Full Text Available The paper deals with determination of principal mechanical properties and the investigation of fatigue behaviour of AZ91 magnesium alloy. The experimental material was made by squeeze casting technique and heat treated to obtain T4 state (solution annealing, when hard, brittle Mg17Al12 intermetallic phase is dissolved. The basic mechanical properties (Young’s modulus, ultimate tensile strength, yield strength, elongation to fracture and reduction of area were determined by static tensile test. Furthermore, fatigue parameters were investigated. The S-N curve on the basis of smooth test bars tested under symmetrical push-pull loading at room temperature was evaluated. The measured data were subsequently used for fitting with suitable regression functions (Kohout & Věchet and Stromeyer for determination of the fatigue parameters. Fatigue limit sigma-c of the studied alloy for 108 cycles is approaching 50 MPa. In addition, the fracture surfaces were observed by scanning electron microscopy. The failure analysis proved that the striations were observed in fatigue crack propagation area and in the area of static fracture was observed the transgranular ductile fracture. The structure of the studied alloy in the basic state and after heat treatment was observed by light and scanning electron microscopy.

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

    Energy Technology Data Exchange (ETDEWEB)

    Feliu, Sebastián, E-mail: sfeliu@cenim.csic.es [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Samaniego, Alejandro [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Barranco, Violeta [Instituto de Ciencias de Materiales de Madrid, ICMM, Consejo Superior de Investigaciones Científicas, CSIC, Sor Juana Inés de la Cruz, 3, Cantoblanco, 28049, Madrid (Spain); El-Hadad, A.A. [Physics Department, Faculty of Science, Al-Azhar University, Nasr City 11884, Cairo (Egypt); Llorente, Irene [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Serra, Carmen [Servicio de Nanotecnologia y Análisis de Superficies, CACTI, Universidade de Vigo, 36310 Vigo (Spain); Galván, J.C. [Centro Nacional de Investigaciones Metalúrgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain)

    2014-03-01

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

  16. The effects of alloying elements on microstructures and mechanical properties of tungsten inert gas welded AZ80 magnesium alloys joint

    Science.gov (United States)

    Li, Hui; Zhang, Jiansheng; Ding, Rongrong

    2017-11-01

    The effects of alloying elements on the macrostructures, microstructures and tensile strength of AZ80 Mg alloy weldments were studied in the present study. The results indicate that with the decrease of Al element content of filler wire, the welding defects of seam are gradually eliminated and the β-Mg17Al12 phases at α-Mg boundaries are refined and become discontinuous, which are beneficial to the improvement of tensile strength. With AZ31 Mg alloy filler wire, the maximum tensile strength of AZ80 weldment is 220 MPa and fracture occurs at the welding seam of joint. It is experimentally proved that robust AZ80 Mg alloy joints can be obtained by tungsten inert gas (TIG) welding process with AZ31 Mg alloy filler wire. However, further study is required to improve the microstructures and reduce welding defects of joint in order to further improve the joining strength of AZ80 Mg alloy joint.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Yufu, E-mail: Yufu.Ren@rockets.utoledo.edu [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Zhou, Huan [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Institute of Biomedical Engineering and Health Sciences, Changzhou University, Changzhou, Jiangsu (China); Nabiyouni, Maryam [Department of Bioengineering, The University of Toledo, Toledo, OH (United States); Bhaduri, Sarit B. [Department of Mechanical, Industrial and Manufacturing Engineering, The University of Toledo, Toledo, OH (United States); Division of Dentistry, The University of Toledo, Toledo, OH (United States)

    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 10 min. 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 7 days 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 5 days 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. - Highlights: • A microwave assisted coating process for biodegradable Mg alloy. • CDHA coatings were successfully developed on AZ31 alloy in minutes. • The as-deposited CDHA coatings significantly reduced the degradation rate of AZ31 alloy. • The CDHA coated AZ31 alloy showed good bioactivity and biocompatibility in vitro. • The microwave assisted coating process can be used as rapid surface modification for bioimplants.

  18. Caña de azúcar en Colombia

    Directory of Open Access Journals (Sweden)

    Ramos Gómez, Oscar Gerardo

    2005-04-01

    Full Text Available This article studies the sugar industry in Colombia, mainly in the Cauca Valley. The analysis is focused on the technical evolution undergone since its inception and the way in which a «sugar culture» evolved. This work also studies the participation of «hacendados» and croppers during the Independence period and the formation of republican oligarchies, their adaptation to the economy modernization processes in the 20th Century, as well as the State intervention and the associative mechanisms the sector used to confront the 1930 crisis. These mechanisms helped to expand the sector. Finally the recent performance of the sugar industry is analyzed, mainly its growth in the seventies and the present efforts at competitiveness, environmental impact and situation in the world trade.

    Este artículo analiza la industria azucarera en Colombia, sobre todo en el Valle del Cauca, su evolución técnica desde sus orígenes y el modo en que se fue configurando una cultura de la caña de azúcar. Además, estudia la participación de los hacendados y cultivadores en la independencia y la formación de las oligarquías republicanas, su adaptación a la modernización de la economía nacional en el siglo XX y la intervención el Estado y los mecanismos asociativos con que hizo frente el sector a la crisis de 1930 y que dieron lugar a una notable expansión del mismo. La parte final del texto explora el desempeño reciente de dicha actividad, su fuerte crecimiento en el decenio de 1970 y sus actuales esfuerzos por mejorar su competitividad, impacto medioambiental y posición en el comercio mundial.

  19. Effect of the chemistry and structure of the native oxide surface film on the corrosion properties of commercial AZ31 and AZ61 alloys

    Energy Technology Data Exchange (ETDEWEB)

    Feliu, Sebastian, E-mail: sfeliu@cenim.csic.es [Centro Nacional de Investigaciones Metalurgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Maffiotte, C. [CIEMAT-DT edificio 30, Avda. Complutense, 22, 28040 Madrid (Spain); Samaniego, A.; Galvan, Juan Carlos [Centro Nacional de Investigaciones Metalurgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Barranco, Violeta [Centro Nacional de Investigaciones Metalurgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Instituto de Ciencias de Materiales de Madrid, ICMM, Consejo Superior de Investigaciones Cientificas, CSIC, Sor Juana Ines de la Cruz, 3, Cantoblanco, 28049, Madrid (Spain)

    2011-08-01

    The purpose of this study has been to advance in knowledge of the chemical composition, structure and thickness of the thin native oxide film formed spontaneously in contact with the laboratory atmosphere on the surface of freshly polished commercial AZ31 and AZ61 alloys with a view to furthering the understanding of protection mechanisms. For comparative purposes, and to more fully describe the behaviour of the native oxide film, the external oxide films formed as a result of the manufacturing process (as-received condition) have been characterised. The technique applied in this research to study the thin oxide films (thickness of just a few nanometres) present on the surface of the alloys has basically been XPS (X-ray photoelectron spectroscopy) in combination with ion sputtering. Corrosion properties of the alloys were studied in 0.6 M NaCl by measuring charge transfer resistance values, which are deduced from EIS (electrochemical impedance spectroscopy) measurements after 1 h of exposure. Alloy AZ61 generally showed better corrosion resistance than AZ31, and the freshly polished alloys showed better corrosion resistance than the alloys in as-received condition. This is attributed to a combination of (1) higher thickness of the native oxide film on the AZ61 alloy and (2) greater uniformity of the oxide film in the polished condition. The formation of an additional oxide layer composed by a mixture of spinel (MgAl{sub 2}O{sub 4}) and MgO seems to diminish the protective properties of the passive layer on the surface of the alloys in as-received condition.

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

    Science.gov (United States)

    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

  1. Effect of Extrusion Speed on the Microstructure and Tensile Properties of AZ31 Alloy

    Directory of Open Access Journals (Sweden)

    Yang Shengnan

    2016-01-01

    Full Text Available The influences of extrusion speed on the microstructure and tensile properties of AZ31 alloy were investigated. The results suggested that the yield and tensile strength of AZ31 alloy decrease but elongation increases with the reduction of extruded speed. High speed extrusion produces fine grains with texture of c-axis perpendicular with extruded direction. The tension deformation is dominated by slip and the formed texture is obstructive for the basal slip, and also the inhomogeneous structure formed at high speed extrusion is harmful to the ductility. Samples extruded at low speed have comparatively homogeneous and coarse microstructure. Twinning provided more tension deformation and the lattice rotation induced by twinning is favorable for the activities of new slip systems, which induced the better ductility of AZ31 alloy.

  2. Grain Refinement and Deformation Mechanisms in Room Temperature Severe Plastic Deformed Mg-AZ31

    Directory of Open Access Journals (Sweden)

    Ludwig Schultz

    2013-07-01

    Full Text Available A Ti-AZ31 composite was severely plastically deformed by rotary swaging at room temperature up to a logarithmic deformation strain of 2.98. A value far beyond the forming limit of pure AZ31 when being equivalently deformed. It is observed, that the microstructure evolution in Mg-AZ31 is strongly influenced by twinning. At low strains the {̅1011} (10̅12 and the {̅1012} (10̅11 twin systems lead to fragmentation of the initial grains. Inside the primary twins, grain refinement takes place by dynamic recrystallization, dynamic recovery and twinning. These mechanisms lead to a final grain size of ≈1 μm, while a strong centered ring fibre texture is evolved.

  3. The effect of extrusion conditions on the properties and textures of AZ31B alloy

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2017-06-01

    Full Text Available The effect of extrusion conditions on the tensile properties and texture of AZ31B alloy has been investigated by means of optical microscopy (OM, scanning electron microscopy (SEM, electron backscattered diffraction (EBSD and tensile tests. It is found that the ultimate tensile strength (UTS, the yield strength (YS and elongation (EN of the extruded AZ31B alloy are more significantly influenced by extrusion velocities in contrast with temperature. Although the extrusion conditions are different, the {112¯0} 〈011¯0〉 texture is the chief texture in the AZ31B after extrusion. Moreover, the extrusion textures become scattered with increasing the temperatures at the same extrusion velocity. As the extrusion velocity is raised at the same temperature, the orientation density of textures increases and the separated textures become relatively concentrated. This leads to the changes of tensile properties at different extrusion conditions.

  4. Influence of The Arrangement of Materials and Microstructural Analysis During FSW of AZ80A

    Directory of Open Access Journals (Sweden)

    Sevvel P.

    2017-09-01

    Full Text Available The main objective of this paper is to produce defect free weldments with improved properties during friction stir welding of dissimilar Mg alloys. The influence of the anisotropic arrangement of materials when AZ80A Mg alloy is taken as advancing side and AZ91C Mg alloy as retreating side and vice versa with respect to their mechanical properties and microstructural characteristics were investigated. The effects of various FSW parameters on the quality of these joints were also analyzed and best optimized FSW parameters were suggested. Defect free sound joints with excellent mechanical properties were produced when AZ80A Mg alloy was positioned at retreating side. At the same time, it seems a little bit difficult to obtain good quality joints with the contrary arrangement of materials. These investigations revealed that materials having inferior plastic deformability must be kept at the advancing side to obtain sound joints during FSW of dissimilar alloys of Magnesium.

  5. Diffusion Bonding and Post-Weld Heat Treatment of Extruded AZ91 Magnesium Alloys

    Directory of Open Access Journals (Sweden)

    Fei LIN

    2015-11-01

    Full Text Available The grain size of as-extruded AZ91 magnesium alloys was refined to 12.31 μm from 21.41 μm by recrystallization annealing. The vacuum diffusion welding of as-annealed AZ91 magnesium alloys was researched. The results showed that the maximum shear strength of joints reached 64.70 MPa in the situation of 10 MPa bonding pressure, 18 Pa vacuum degree, 470 °C bonding temperature and 90 min bonding time; both bonding temperature and time are the main influence factors on as-extruded AZ91 magnesium alloys diffusion welding. Then the diffusion welded specimens were annealed, and the shear strength of joints was further improved to 76.93 MPa.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9699

  6. Korozní odolnost tvářených hořčíkových slitin AZ31 a AZ61 v Hankovì roztoku

    Czech Academy of Sciences Publication Activity Database

    Tkacz, J.; Slouková, K.; Minda, J.; Drábiková, J.; Fintová, Stanislava; Doležal, P.; Wasserbauer, J.

    2016-01-01

    Roč. 60, č. 4 (2016), s. 101-106 ISSN 1804-1213 Institutional support: RVO:68081723 Keywords : corrosion * AZ31 magnesium alloy * AZ61 magnesium alloy Subject RIV: JK - Corrosion ; Surface Treatment of Materials https://www.degruyter.com/view/j/kom.2016.60.issue-4/kom-2016-0016/kom-2016-0016. xml ?format=INT

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

    Science.gov (United States)

    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

  8. Corrosion behaviour and in vitro/in vivo biocompatibility of surface-modified AZ31 alloy; Comportamiento frente a la corrosion y biocompatibilidad in vitrolin vivo de la aleacion AZ31 modificada superficialmente

    Energy Technology Data Exchange (ETDEWEB)

    Carboneras, M.; Iglesias, C.; Perez-Maceda, B. T.; Valle, J. A. de; Garcia-Alonso, M. C.; Alobera, M. A.; Clemente, C.; Rubio, J. C.; Escudero, M. I.; Lozano, R. M.

    2011-07-01

    The present work evaluates the corrosion behaviour and the in vitro/in vivo biocompatibility of the AZ31 magnesium alloy, which fulfills the mechanical requirements of bone. The corrosion kinetic of as-received AZ31 alloy was not compatible with the cell growth. To improve its performance, the AZ31 alloy was surface modified by a chemical conversion treatment in hydrofluoric acid. The magnesium fluoride layer generated by the surface treatment of AZ31 alloy enhances its corrosion behaviour, allowing the in vitro growth of osteoblastic cells over the surface and the in vivo formation of a highly compact layer of new bone tissue. These results lead to consider the magnesium fluoride coating as necessary for potential use of the AZ31 alloy as biodegradable and absorbable implant for bone repair. (Author) 18 refs.

  9. Patrón de consumo e ingestas recomendadas de azúcar

    OpenAIRE

    Joan Quiles i Izquierdo

    2013-01-01

    Los azúcares son hidratos de carbono con sabor dulce que proveen energía al organismo. El cerebro adulto utiliza aproximadamente 140 g de glucosa al día, cantidad que puede representar hasta el 50% del total de hidratos de carbono que se consumen. En nuestro país el patrón de consumo de azúcar en alimentos permanece constante, mientras que el consumo de bebidas refrescantes presenta un aumento en los últimos cuatro años. La Encuesta Nacional de Ingesta Dietética de España (ENIDE, 2010-11) est...

  10. La trehalosa. Parte I: su presencia en la caña de azúcar

    OpenAIRE

    Eduardo L. Ramos; Susana Ravelo; Enrique Muñoz; Carlos Pérez

    2009-01-01

    Varios de los problemas que se presentan al tratar de elevar la eficiencia industrial durante la producción de azúcar, están asociados fundamentalmente a la capacidad de la caña para formar en sus jugos la sacarosa y sus monosacáridos constituyentes. Se ha determinado que luego del corte se acentúa la formación de azúcares, como: la D-Xilosa, la Lactosacarosa, las Kestosas, la Rafinosa y varios polisacáridos, sustancias que impiden el desarrollo normal del cristal de sacarosa y disminuyen la ...

  11. Az egyetemek három missziójának vizsgálata

    OpenAIRE

    Zuti, Bence

    2014-01-01

    Ma már az egyetemek az intézményi stratégia kialakítása mentén is arra törekednek, hogy nemzetközi színtereken is megjelenjenek, hazai és külföldi kereteken belül is ismert és elismert legyen oktatásuk színvonala, kutatómunkájuk és harmadik missziós tevékenységük értéke.

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

    Science.gov (United States)

    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.

  13. Comportamiento mecánico de la aleación AZ31 reforzada con nanofibras de carbono

    Directory of Open Access Journals (Sweden)

    Adeva, P.

    2010-12-01

    Full Text Available The aim of this study is to investigate the effect of reinforcing AZ31 with carbon nanofibres. The materials AZ31, AZ31-1 % C y AZ31-2 % C were produced by a conventional powder metallurgy route consisting of mechanical mixing of nanofibres and powders of AZ31, cool compactation and extrusion at 350 °C. After extrusion the three materials exhibited a recrystallized microstructure of similar grain size, fine and rather inhomogeneous. Furthermore, they presented a weak fibre texture with basal plane parallel to the extrusion direction. The tensile properties were affected by the nanofibres presence only at 100 °C. At this temperature, yield strength and tensile strength were 30% higher than in the unreinforced alloy.

    En este trabajo se ha estudiado el efecto de la adición de nanofibras de carbono en las propiedades mecánicas de la aleación AZ31 procesada por una ruta pulvimetalúrgica convencional. Se prepararon tres materiales, AZ31, AZ31- 1 % C y AZ31-2 % C. Tras una mezcla mecánica de las nanofibras con los polvos de AZ31, se precompactaron en frío y se extruyeron a 350 °C. Los tres presentan una microestructura recristalizada con un tamaño de grano similar, fino aunque algo heterogéneo. Los tres materiales presentan una débil textura de fibra con el plano basal paralelo a la dirección de extrusión. Las propiedades mecánicas a tracción únicamente se ven afectadas por la presencia de nanofibras a 100 °C superando los materiales reforzados en un 30 % a los valores de límite elástico y resistencia de la aleación sin reforzar.

  14. 77 FR 2242 - Radio Broadcasting Services; Ehrenberg, First Mesa, Kachina Village, Wickenburg, and Williams, AZ...

    Science.gov (United States)

    2012-01-17

    ... COMMISSION 47 CFR Part 73 [MB Docket No. 08-85; RM-11427, RM-11517, RM-11518, RM-11519; DA 11- 2059] Radio Broadcasting Services; Ehrenberg, First Mesa, Kachina Village, Wickenburg, and Williams, AZ, and Needles, CA... Radio, Inc. (RM-11517) and Univision Radio License Corporation (RM-11518), which are mutually exclusive...

  15. 75 FR 11939 - DNS Electronics, Chandler, AZ; Notice of Termination of Investigation

    Science.gov (United States)

    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, Chandler...

  16. Effects of organic acid pickling on the corrosion resistance of magnesium alloy AZ31 sheet

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Blawert, C.; Scharnagl, N.

    2010-01-01

    Organic acids were used to clean AZ31 magnesium alloy sheet and the effect of the cleaning processes on the surface condition and corrosion performance of the alloy was investigated. Organic acid cleanings reduced the surface impurities and enhanced the corrosion resistance. Removal of at least 4...

  17. Laser cladding of Zr-based coating on AZ91D magnesium alloy for ...

    Indian Academy of Sciences (India)

    based coating made of Zr powder was fabricated on AZ91D magnesium alloy by laser cladding. The microstructure of the coating was characterized by XRD, SEM and TEM techniques. The wear resistance of the coating was evaluated under dry ...

  18. Compression Deformation Behavior of AZ81 Magnesium Alloy at Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Xiaoping Luo

    2014-01-01

    Full Text Available The hot deformation behavior of an AZ81 magnesium alloy was investigated by hot compressive testing on a Gleeble-1500 thermal mechanical simulator in the temperature range from 200 to 400°C and in the strain rate range of 0.001–5 s−1. The relationships among flow stress, strain rate, and deformation temperature were analyzed, and the deformation activation energy and stress exponent were calculated. The microstructure evolution of the AZ81 magnesium alloy under high deformation was examined. The results indicated that the maximum value of the flow stress increased with the decrease of deformation temperature and the increase of strain rate. When the deformation temperature is constant, the flow stress of the AZ81 magnesium alloy increases with the increase of strain rate, which can be demonstrated by a Zener-Hollomon parameter in a hyperbolic-sine-type equation with a hot compression deformation activation energy of 176.01 KJ/mol and basic hot deformation material factors A, n, and a in the analytical expression of the AZ81 magnesium alloy flow stress of 3.21227×1014 s−1, 7.85, and 0.00866 MPa, respectively.

  19. 75 FR 5115 - Temporary Concession Contract for Lake Mead National Recreation Area, AZ/NV

    Science.gov (United States)

    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 Nevada...

  20. 75 FR 10552 - Noise Exposure Map Notice for Chandler Municipal Airport, Chandler, AZ

    Science.gov (United States)

    2010-03-08

    ... Federal Aviation Administration Noise Exposure Map Notice for Chandler Municipal Airport, Chandler, AZ... Administration (FAA) announces its determination that the noise exposure maps submitted by City of Chandler, for...: The effective date of the FAA's determination on the noise exposure maps is February 19, 2010. FOR...

  1. 76 FR 30907 - Proposed Foreign-Trade Zone-Eloy, AZ; Application

    Science.gov (United States)

    2011-05-27

    ... Foreign-Trade Zones Board Proposed Foreign-Trade Zone--Eloy, AZ; Application An application has been submitted to the Foreign-Trade Zones Board (the Board) by the City of Eloy to establish a general-purpose foreign- trade zone at sites in Pinal County, Arizona, adjacent to the Phoenix U.S. Customs and Border...

  2. Selectividad de caña de azúcar en bovinos

    Directory of Open Access Journals (Sweden)

    E. M. Aranda

    2009-01-01

    Full Text Available Se condujo este trabajo con el objetivo de conocer la aceptación del forraje de caña de azúcar integral en la dieta con base de pasto para bovinos adultos fistulados en rumen y duodeno estabulados; para ello, se ofreció pasto estrella africana (Cynodon plectostachyus y caña de azúcar (Saccharum officinarum mezclada con 1% de urea a voluntad, por separado. Se midió la composición de los alimentos, consumo de materia seca, pH ruminal y duodenal. Se utilizaron técnicas de la estadística descriptiva, como la media aritmética y error estándar. La proteína, paredes celulares y hemicelulosa fueron mayores para el pasto estrella. El consumo de MS fue de 46.6 y 38.1% para la caña de azúcar y el pasto, respectivamente; el pH ruminal tuvo valores de 7.3, disminuyendo a 6.7 a las 12 h.; y el pH de la digesta duodenal osciló de 3.7 a 4.7. Se concluye que hubo mayor aceptación por la caña de azúcar y el pH ruminal no indica valores que afecten la celulólisis ruminal.

  3. 78 FR 40381 - Establishment of Class E Airspace; Grand Canyon, AZ

    Science.gov (United States)

    2013-07-05

    ...This action establishes Class E airspace at the Grand Canyon VHF Omni-Directional Radio Range/Distance Measuring Equipment (VOR/DME) navigation aid, Grand Canyon, AZ, to facilitate vectoring of Instrument Flight Rules (IFR) aircraft under control of Los Angeles Air Route Traffic Control Center (ARTCC). This improves the safety and management of IFR operations within the National Airspace System.

  4. 75 FR 35504 - San Rafael Cattle Company; Habitat Conservation Plan; Santa Cruz County, AZ

    Science.gov (United States)

    2010-06-22

    ... Fish and Wildlife Service San Rafael Cattle Company; Habitat Conservation Plan; Santa Cruz County, AZ... Conservation Plan in support of incidental take permit application. SUMMARY: San Rafael Cattle Company... the future: Sonoran tiger salamander (Ambystoma mavortium stebbinsi), Gila chub (Gila intermedia...

  5. 78 FR 63869 - Change of Using Agency for Restricted Areas R-2309 and R-2312, AZ

    Science.gov (United States)

    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 in...

  6. 77 FR 20356 - Foreign-Trade Zone 277-Western Maricopa County, AZ; Application for Manufacturing Authority...

    Science.gov (United States)

    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) for...

  7. Synthesis of dittmarite/Mg(OH){sub 2} composite coating on AZ31 using hydrothermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Qing, E-mail: qzhaoyuping@bit.edu.cn; Mahmood, Waqas; Zhu, Yanying

    2016-03-30

    Highlights: • Synthesis of dittmarite Mg(OH){sub 2} coating on AZ31 alloy by hydrothermal method. • The mechanism of composite coating growth and its characterizations. • The coating is corrosion resistant significantly. • Lack of hydroxyl deposition on the coating surface. • Strong adhesion between the coating and the substrate. • The synthesized coating meets the cytotoxicity standards. - Abstract: In this work, we have used hydrothermal method for the synthesis of dittmarite/Mg(OH){sub 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 of Magnesium alloy AZ91-HP cast in permanent and non-permanent moulds

    DEFF Research Database (Denmark)

    Tiedje, Niels; Sørensen, Rasmus Kirkegaard; Albachari, Sami

    2003-01-01

    Casting of different geometries were made with AZ91-HP in different moulding media, so that a range of cooling conditions were obtained. Cooling curves were measured and compared to the microstructures found in the castings. It was shown that segregation in the alloy is highly dependent on cooling...

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

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, S.F., Westinghouse Hanford

    1996-06-12

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

  10. Analysis of dynamic deformation behavior of AZ31 using Taylor Rod on Anvil Impact Tests

    Science.gov (United States)

    Sharma, Maruwada Sukanya; Kirtley, Daniel; Gokhale, Arun; Thadhani, Naresh

    2017-06-01

    The dynamic behavior and detailed microstructural characterization of rolled magnesium alloy AZ31 is described in this work. Magnesium alloys have gained considerable importance as they possess a high strength-to-weight ratio. The goal of the current work is to provide an insight on the dynamic deformation of AZ31 magnesium alloys. Taylor rod-on-anvil impact tests have been conducted at different velocities, on rods machined along the rolling and transverse directions of the as-rolled AZ31 plate, in order to capture the effects of anisotropy on the dynamic deformation behavior. The experiments used laser beam interruption to measure the impact velocity of the samples and high-speed digital imaging to capture transient deformation states. The impacted samples showed anisotropic deformation resulting in an elliptical impact surface foot print. Additionally, detailed orientation maps and micrographs revealed extensive twinning along with some cracks on the impact faces of the samples. Quantitative microscopy revealed that the surface area per unit volume of twins at least tripled under all impact conditions. In this presentation evolution of microstructure and anisotropy in rolled AZ31 samples subjected to Taylor rod-on-anvil impact tests will be discussed.

  11. Az adóráták és a korrupció hatása az adóbevételekre. Az OECD-országok összehasonlítása, 2000-2004

    OpenAIRE

    Lackó, Mária

    2009-01-01

    A tanulmány az adóráták (különös tekintettel a munkát sújtó adórátákra) és a korrupció szintjének (mint extraadónak) az együttes hatását vizsgálja az adóbevételek GDP-hez viszonyított arányára 27 OECD-ország 2000-2004. évi adatai alapján. Az adóéknek a korrupció szintjével kombinált interakciója és a megfelelő adóbevételek közötti grafikus ábrázolásban egy Laffer-görbe típusú kapcsolat látható. A cikk megmutatja, hogy ez az összefüggés több egymástól elkülöníthető hatás eredője: az egyik az a...

  12. La dictadora en La dama de cristal, de Zelmar Acevedo Díaz (The Dictator in La dama de cristal, by Zelmar Acevedo Díaz)

    OpenAIRE

    Elizabeth Abagail Sampson

    2015-01-01

    El estudio aborda el tema de la dictadora en La dama de cristal (1999), de Zelmar Acevedo Díaz (Argentina, 1951). Se comparan con otras novelas sobre el mismo tema y se examinan coincidencias o disparidades entre la representación literaria femenina y masculina del autoritarismo. La dictadura latinoamericana como fenómeno político ha persistido en América Latina con diferentes matices ideológicos. Gabriel García Márquez en El otoño del patriarca, Mario Vargas Llosa en La fiesta del Chivo o Lu...

  13. Bioetanol de la caña de azúcar

    Directory of Open Access Journals (Sweden)

    N. Aguilar-Rivera

    2007-01-01

    Full Text Available La búsqueda de la viabilidad y desarrollo de la agroindustria de la caña de azúcar es ya una política imperativa. La producción de caña y azúcar constituyen la principal agroindustria del país, con presencia en 57 ingenios azucareros, localizados en 15 estados de la república. Sin embargo, la actual ineficiencia productiva, altos costos y otras causas —como la entrada de jarabe de maíz de alta fructosa (HFCS de menor costo— han desplazado el consumo interno de azúcar de caña, principalmente en bebidas embotelladas. Todos estos factores han contribuido a la actual y prolongada crisis del sector azucarero. Por lo tanto, la industria debe reestructurarse y reducir la producción de azúcar hacia la competitividad, con la alternativa del etanol combustible en la búsqueda de un futuro para la industria azucarera en México. Con la producción de etanol (EtOH a gran escala, por parte de los ingenios azucareros, es posible visualizar un nuevo y futuro mercado de uso de energías renovables en México, oportunidades para la exportación e incrementar los beneficios ambientales y económicos a través de su uso. La flexibilidad de la producción combinada, de azúcar y etanol en los ingenios, permitirá alcanzar esquemas y objetivos ambientales como nación. Para la industria azucarera, su mayor competidesafío, en este sentido, representa disminuir los costos actuales de producción de etanol a través del uso de la ingeniería genética, uso de diferentes materias primas y la totalidad de la planta de caña de azúcar e introducir mejoras tecnológicas.

  14. Simulation for Carbon Nanotube Dispersion and Microstructure Formation in CNTs/AZ91D Composite Fabricated by Ultrasonic Processing

    Science.gov (United States)

    Yang, Yuansheng; Zhao, Fuze; Feng, Xiaohui

    2017-10-01

    The dispersion of carbon nanotubes (CNTs) in AZ91D melt by ultrasonic processing and microstructure formation of CNTs/AZ91D composite were studied using numerical and physical simulations. The sound field and acoustic streaming were predicted using finite element method. Meanwhile, optimal immersion depth of the ultrasonic probe and suitable ultrasonic power were obtained. Single-bubble model was used to predict ultrasonic cavitation in AZ91D melt. The relationship between sound pressure amplitude and ultrasonic cavitation was established. Physical simulations of acoustic streaming and ultrasonic cavitation agreed well with the numerical simulations. It was confirmed that the dispersion of carbon nanotubes was remarkably improved by ultrasonic processing. Microstructure formation of CNTs/AZ91D composite was numerically simulated using cellular automation method. In addition, grain refinement was achieved and the growth of dendrites was changed due to the uniform dispersion of CNTs.

  15. The evolution of microstructures, corrosion resistance and mechanical properties of AZ80 joints using ultrasonic vibration assisted welding process

    Science.gov (United States)

    Li, Hui; Zhang, Jiansheng

    2017-12-01

    The evolution of microstructures, corrosion resistance and mechanical properties of AZ80 joints using an ultrasonic vibration assisted welding process is investigated. The results show that, with ultrasonic vibration treatment, a reliable AZ80 joint without defects is obtained. The coarsening α-Mg grains are refined to about 83.5  ±  3.3 µm and the continuous β-Mg17Al12 phases are broken to granular morphology, owing to the acoustic streaming effect and the cavitation effect evoked by ultrasonic vibration. Both immersion and electrochemical test results indicate that the corrosion resistance of the AZ80 joint welded with ultrasonic vibration is improved, attributed to microstructure evolution. With ultrasonic power of 900 W, the maximum tensile strength of an AZ80 specimen is 261  ±  7.5 MPa and fracture occurs near the heat affected zone of the joint.

  16. Corrosion behavior of friction stir welded AZ31B Mg alloy - Al6063 alloy joint

    Directory of Open Access Journals (Sweden)

    B. Ratna Sunil

    2016-12-01

    Full Text Available In the present work, AZ31B Mg alloy and Al6063 alloy-rolled sheets were successfully joined by friction stir welding. Microstructural studies revealed a sound joint with good mechanical mixing of both the alloys at the nugget zone. Corrosion performance of the joint was assessed by immersing in 3.5% NaCl solution for different intervals of time and the corrosion rate was calculated. The joint has undergone severe corrosion attack compared with both the base materials (AZ31B and Al6063 alloys. The predominant corrosion mechanism behind the high corrosion rate of the joint was found to be high galvanic corrosion. From the results, it can be suggested that the severe corrosion of dissimilar Mg–Al joints must be considered as a valid input while designing structures intended to work in corroding environment.

  17. Hardness evolution of AZ80 magnesium alloy processed by HPT at different temperatures

    Directory of Open Access Journals (Sweden)

    Saad A. Alsubaie

    2017-10-01

    Full Text Available Discs of an extruded AZ80 magnesium alloy were processed by high-pressure torsion (HPT using 6.0 GPa up to 10 turns at different temperatures (296 K and 473 K. The disc surfaces and cross-sectional planes were examined before and after processing using scanning electron microscopy (SEM and Vickers microhardness (Hv. The microhardness results at the surface show differences in the strength of the material as a function of distance from the disc centres up to saturation, as well as a function of distance from the bottom to the surface in the cross-sectional plane. This study analyses the effect of processing temperature on the evolution of microhardness in the AZ80 magnesium alloy processed by high-pressure torsion. Keywords: Hardness, High-pressure torsion, Magnesium alloy, Severe plastic deformation

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

    Directory of Open Access Journals (Sweden)

    Agnieszka Witecka, Akiko Yamamoto, Henryk Dybiec and Wojciech Swieszkowski

    2012-01-01

    Full Text Available 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.

  19. Study on Corrosion and Stress Corrosion Cracking Behaviors of AZ31 Alloy in Sodium Sulfate Solution

    Science.gov (United States)

    He, Xiuli; Yan, Zhifeng; Liang, Hongyu; Wei, Yinghui

    2017-05-01

    The potentiodynamic polarization test and slow strain rate tensile test were carried out in 3.5 wt.% Na2SO4 solution with different pH values (2, 7, and 12). It was found that the SCC susceptibility of AZ31 magnesium alloy in 3.5 wt.% Na2SO4 solution was deteriorated significantly with the decreasing pH. This was consistent with the electrochemical properties. There were filiform corrosion forms on the specimen surface after slow strain rate tensile test in 3.5 wt.% Na2SO4 solution, which indicated the characteristics of general corrosion. Moreover, there were multiple stress corrosion crack initiation sources. The SCC fracture of AZ31 magnesium alloy in air was a mix type, while it was cleavage fracture in 3.5 wt.% Na2SO4 solution.

  20. Transition in Deformation Mechanism of AZ31 Magnesium Alloy during High-Temperature Tensile Deformation

    Directory of Open Access Journals (Sweden)

    Masafumi Noda

    2011-01-01

    Full Text Available Magnesium alloys can be used for reducing the weight of various structural products, because of their high specific strength. They have attracted considerable attention as materials with a reduced environmental load, since they help to save both resources and energy. In order to use Mg alloys for manufacturing vehicles, it is important to investigate the deformation mechanism and transition point for optimizing the material and vehicle design. In this study, we investigated the transition of the deformation mechanism during the high-temperature uniaxial tensile deformation of the AZ31 Mg alloy. At a test temperature of 523 K and an initial strain rate of 3×10−3 s-1, the AZ31 Mg alloy (mean grain size: ~5 μm exhibited stable deformation behavior and the deformation mechanism changed to one dominated by grain boundary sliding.

  1. Hammer forging process of lever drop forging from AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    A. Gontarz

    2013-07-01

    Full Text Available The results of theoretical and experimental analysis of hammer forging process of lever drop forging from AZ31 magnesium alloy are presented in this paper. In order to design a process guaranteeing obtaining a proper product, numerous simulations were made, in which material flow kinematics, strain and damage criterion distributions and forging energy were analyzed. On the basis of the obtained results, the analysis of limiting phenomena, which could appear during the process, was made. Experimental tests in industrial conditions according to designed technology were carried out. Good quality of drop forgings were obtained. On the basis of conducted research, it was stated that hammer forging of lever drop forging from AZ31 magnesium alloy is possible.

  2. Theoretical and experimental research of hammer forging process of RIM from AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    A. Gontarz

    2014-10-01

    Full Text Available The results of theoretical analysis and experimental tests of hammer forging process of rim part from AZ31 magnesium alloy are presented in this paper. On the basis of numerical simulation results, the analysis of limiting phenomena was made. These phenomena include: possibility of overlapping presence, not filling of die impression, overheating of material and cracks. The results of theoretical analysis provided the support for planning of experimental tests in industrial conditions. Forging tests were conducted in one of Polish forming plants, applying steam-air hammer of blow energy 63 kJ. On the basis of experimental verification, it was stated that it is possible to obtain rim forging from AZ31 alloy of assumed quality in the hammer forging process.

  3. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  4. La dictadora en La dama de cristal, de Zelmar Acevedo Díaz (The Dictator in La dama de cristal, by Zelmar Acevedo Díaz

    Directory of Open Access Journals (Sweden)

    Elizabeth Abagail Sampson

    2015-11-01

    Full Text Available El estudio aborda el tema de la dictadora en La dama de cristal (1999, de Zelmar Acevedo Díaz (Argentina, 1951. Se comparan con otras novelas sobre el mismo tema y se examinan coincidencias o disparidades entre la representación literaria femenina y masculina del autoritarismo. La dictadura latinoamericana como fenómeno político ha persistido en América Latina con diferentes matices ideológicos. Gabriel García Márquez en El otoño del patriarca, Mario Vargas Llosa en La fiesta del Chivo o Luis Spota en El tiempo de la ira tratan este hecho para perfilar sus rasgos distintivos. Existe un caso particular en que el autoritarismo lo encarna una mujer. This study focuses on the theme of female dictator in La dama de cristal (1999, by Zelmar Acevedo Díaz (Argentina, 1951. It is compared with other novels on the same theme and an analysis is carried out of coincidences or disparities between the feminine and masculine literary representation of authoritarianism. Latin American dictatorships are a political phenomenon that has persisted in Latin America with different ideological tones. Gabriel García Márquez in El otoño del patriarca; Mario Vargas Llosa in La fiesta del Chivo or Luis Spota in El tiempo de la ira have approached this issue to profile its distinctive features. There is one particular case of a female dictator.

  5. Porfirio Díaz en la historiografía masónica mexicana

    Directory of Open Access Journals (Sweden)

    Marco Antonio Flores Zavala

    2015-01-01

    Full Text Available En este artículo se analiza la presencia del general Porfirio Díaz en la historiografía masónica mexicana. Parala redacción de este texto se recurrió a las obras de José María Mateos (Historia de la masonería en Méxicodesde 1806 hasta 1884, Richard Chism (Una contribución a la historia masónica de México y Luis J. Zalce(Apuntes para la historia de la masonería en México, de mis lecturas y mis recuerdos. El cuestionario esbásico: ¿Qué fuentes documentales utilizaron los autores para redactar sus textos? ¿Cómo examinan laactuación del general Díaz, como actor de un régimen o un hermano masón? Pese a lo elemental de laspreguntas, éstas colaboran para situar parte de los tópicos y de las formas en que fueron redactadas lashistorias de la masonería en México. El artículo está integrado con dos secciones. En la primera se esboza unabiografía del general Díaz y se presentan las obras que se definen como historiografía masónica mexicana. Lasegunda sección presenta la descripción de las obras y cómo examinaron la presencia de Díaz en lamasonería.

  6. Thermal stability of magnesium alloy AZ91 prepared by severe plastic deformation

    Directory of Open Access Journals (Sweden)

    Roman Štěpánek

    2013-12-01

    Full Text Available This paper deals with the thermal stability of ultrafine-grained alloy AZ91 prepared by means of ECAP (Equal Channel Angular Pressing method. Annealing experiments were conducted isochronally for 30 minutes in the temperature range of 220 to 400 °C in argon atmosphere. EBSD (Electron Backscatter Diffraction method was used to image the changes in microstructure due to increased temperature.

  7. Laser offset welding of AZ31B magnesium alloy to 316 stainless steel

    OpenAIRE

    Casalino, G.; Guglielmi, P; LORUSSO, V.D.; MORTELLO, M; PEYRE, P; Sorgente, D.

    2016-01-01

    In this paper, the feasibility of using a fiber laser to perform a dissimilar metal joining was explored. AZ31B magnesium and 316 stainless steel were autogenously joined in butt configuration. The weldability between different materials is often compromised by a large difference in thermal properties and poor metallurgical compatibility. Thus, the beam was focused onto the top surface of the magnesium plate, at a certain distance from the interfaces (offset), and without using any interlayer...

  8. 75 FR 26098 - Safety Zone; Under Water Clean Up of Copper Canyon, Lake Havasu, AZ

    Science.gov (United States)

    2010-05-11

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Under Water Clean Up of Copper Canyon, Lake....T11-179 to read as follows: Sec. 165.T11-179 Safety zone; Copper Canyon Clean Up, Lake Havasu, AZ. (a... establishing a temporary safety zone on the navigable waters of Lake Havasu in the Copper Canyon in support of...

  9. Superplastic behaviour of an AZ61 alloy processed by equal channel angular extrusion

    OpenAIRE

    M. Eddahbi; Ruano, Oscar Antonio

    2006-01-01

    This study is concerned with microstructural and mechanical characterization of the superplastic behaviour of a magnesium base AZ61 alloy processed by equal channel angular extrusion (ECA). Microscopic examinations showed that the microstructure after ECA was homogeneous and the grain size was about 5 mm. The extruded material showed better mechanical properties than the rolled material. The strain rate sensitivity exponent, at 250ºC, was 0.5 at strain rates ranging from 10-4 to 5 . 10-...

  10. 78 FR 25404 - Proposed Establishment of Class E Airspace; Grand Canyon, AZ

    Science.gov (United States)

    2013-05-01

    ...This action proposes to establish Class E airspace at the Grand Canyon VHF Omni-Directional Radio Range/Distance Measuring Equipment (VOR/DME) navigation aid, Grand Canyon, AZ, to facilitate vectoring of Instrument Flight Rules (IFR) aircraft under control of Los Angeles Air Route Traffic Control Center (ARTCC). The FAA is proposing this action to enhance the safety and management of aircraft operations within the National Airspace System.

  11. El comercio catalán del azúcar en el siglo XIV

    Directory of Open Access Journals (Sweden)

    Coulon, Damien

    2001-12-01

    Full Text Available The purpose of this article is to document some aspects of the sugar trade in fourteenth century Catalonia. More especially it aims to highlight the following paradox: Barcelonese traders regularly travelled to Eastern Mediterranean to fetch sugar, yet sugar cane had been introduced in the Iberian Peninsula as early as the tenth century. After presenting the main stages of sugar production until the fourteenth century, the author examines recent works on the history of sugar production in Eastern Mediterranean. He also reviews various documents on the exportation of sugar to Catalonia in the fourteenth century, mostly from the Barcelonese archives. The article ends with a table of the different kinds of sugar produced and exported during the period under review.

    Este artículo tiene por objeto presentar algunos aspectos del comercio catalán del azúcar en el siglo XIV y, en particular, resolver la siguiente paradoja: los comerciantes barceloneses iban efectivamente de manera regular a buscar este producto en el Mediterráneo oriental cuando la caña de azúcar había sido introducida en la Península Ibérica desde el siglo X. Después de haber presentado las principales etapas de la expansión de este cultivo hasta el siglo XIV, el autor examina con detalle algunos trabajos recientes relativos a la producción de azúcar en el Mediterráneo oriental así como los documentos que atestiguan su exportación hacia Cataluña en el siglo XIV, centrándose especialmente en las fuentes barcelonesas. El estudio se completa con un cuadro de los diferentes tipos de azúcar encontrados.

  12. Residual stresses of a magnesium alloy (AZ31 welded by the friction stir welding processes

    Directory of Open Access Journals (Sweden)

    Kouadri-Henni A.

    2016-01-01

    Full Text Available The objective of this study was to evaluate the residual stresses of FSW welding magnesium alloys (AZ31. The results show that the FSW processes lead to the formation of several distinct zones with differing mechanical properties. The residual stresses evolution have been explained by the heterogeneous modifications of the microstructure particularly a marked decrease in the grain size, a high modification of the crystallographic texture and the different anisotropic properties resulting from plasticity induced by the FSW process.

  13. Theoretical and experimental research of hammer forging process of RIM from AZ31 magnesium alloy

    OpenAIRE

    Gontarz, A.

    2014-01-01

    The results of theoretical analysis and experimental tests of hammer forging process of rim part from AZ31 magnesium alloy are presented in this paper. On the basis of numerical simulation results, the analysis of limiting phenomena was made. These phenomena include: possibility of overlapping presence, not filling of die impression, overheating of material and cracks. The results of theoretical analysis provided the support for planning of experimental tests in industrial conditions. Forging...

  14. Hammer forging process of lever drop forging from AZ31 magnesium alloy

    OpenAIRE

    Gontarz, A.; Z. Pater; K. Drozdowski

    2013-01-01

    The results of theoretical and experimental analysis of hammer forging process of lever drop forging from AZ31 magnesium alloy are presented in this paper. In order to design a process guaranteeing obtaining a proper product, numerous simulations were made, in which material flow kinematics, strain and damage criterion distributions and forging energy were analyzed. On the basis of the obtained results, the analysis of limiting phenomena, which could appear during the process, was made. Exper...

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

    Science.gov (United States)

    Zovkic, Iva B; Walters, Brandon J

    2015-06-01

    Histone variant exchange is a novel epigenetic regulator of cognition. We speculate that H2A.Z, a variant of canonical histone H2A, exerts unique effects on transcription during distinct stages of memory formation, ultimately acting to maintain memory of previous transcriptional states and poise genes for re-activation. Hippocampus-dependent memory formation is initiated by transient expression of memory-related genes, which support the storage of recently acquired memories. Soon after, memories undergo systems consolidation, which transfers memories from the hippocampus to the cortex for long-term storage, and requires ongoing re-activation of memory-related genes. We speculate that learning-induced H2A.Z eviction from nucleosomes initially contributes to stimulus-induced transcriptional induction needed for the initial process of memory consolidation. During systems consolidation, we speculate that delayed incorporation of H2A.Z into nucleosomes of memory-related genes in the cortex is needed to poise genes for rapid re-activation, thus supporting the long-term process of memory stabilization. © 2015 WILEY Periodicals, Inc.

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

    Science.gov (United States)

    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.

  17. High temperature formability of graphene nanoplatelets-AZ31 composites fabricated by stir-casting method

    Directory of Open Access Journals (Sweden)

    Muhammad Rashad

    2016-12-01

    Full Text Available Outstanding mechanical properties of graphene nanoplatelets (GNPs make them ideal reinforcement for mass production of composites. In this research, the composites were fabricated by stir-casting method. GNPs were added in 1.5 and 3.0 wt.% into Mg–3wt.% Al–1wt.% Zn (AZ31 magnesium alloy. As cast ingots were preheated for one hour and extruded at 350 °C with extrusion ratio of 5.2:1. As extruded AZ31-GNPs composites were micro-structurally characterized with X-ray diffraction, optical microscopy and scanning electron microscopy. Vickers micro-hardness of synthesized materials was investigated both in parallel and perpendicular to extrusion directions. Room temperature mechanical testing revealed that with increasing GNP's content, tensile fracture strain was remarkably increased without significant compromise in tensile strength. Furthermore, as extruded AZ31-3GNPs composites were subjected to tensile testing at temperatures ranging from 75 °C to 300 °C with initial strain rate of 2 × 10−3 s−1 to evaluate high temperature formability of composite. It was found that like CNTs, GNPs also have the potential to sustain tensile strength at high temperatures.

  18. Cerium Addition Improved the Dry Sliding Wear Resistance of Surface Welding AZ91 Alloy

    Directory of Open Access Journals (Sweden)

    Qingqiang Chen

    2018-02-01

    Full Text Available In this study, the effects of cerium (Ce addition on the friction and wear properties of surface welding AZ91 magnesium alloys were evaluated by pin-on-disk dry sliding friction and wear tests at normal temperature. The results show that both the friction coefficient and wear rate of surfacing magnesium alloys decreased with the decrease in load and increase in sliding speed. The surfacing AZ91 alloy with 1.5% Ce had the lowest friction coefficient and wear rate. The alloy without Ce had the worst wear resistance, mainly because it contained a lot of irregularly shaped and coarse β-Mg17Al12 phases. During friction, the β phase readily caused stress concentration and thus formed cracks at the interface between β phase and α-Mg matrix. The addition of Ce reduced the size and amount of Mg17Al12, while generating Al4Ce phase with a higher thermal stability. The Al-Ce phase could hinder the grain-boundary sliding and migration and reduced the degree of plastic deformation of subsurface metal. Scanning electron microscopy observation showed that the surfacing AZ91 alloy with 1.5% Ce had a total of four types of wear mechanism: abrasion, oxidation, and severe plastic deformation were the primary mechanisms; delamination was the secondary mechanism.

  19. Cerium Addition Improved the Dry Sliding Wear Resistance of Surface Welding AZ91 Alloy.

    Science.gov (United States)

    Chen, Qingqiang; Zhao, Zhihao; Zhu, Qingfeng; Wang, Gaosong; Tao, Kai

    2018-02-06

    In this study, the effects of cerium (Ce) addition on the friction and wear properties of surface welding AZ91 magnesium alloys were evaluated by pin-on-disk dry sliding friction and wear tests at normal temperature. The results show that both the friction coefficient and wear rate of surfacing magnesium alloys decreased with the decrease in load and increase in sliding speed. The surfacing AZ91 alloy with 1.5% Ce had the lowest friction coefficient and wear rate. The alloy without Ce had the worst wear resistance, mainly because it contained a lot of irregularly shaped and coarse β-Mg 17 Al 12 phases. During friction, the β phase readily caused stress concentration and thus formed cracks at the interface between β phase and α-Mg matrix. The addition of Ce reduced the size and amount of Mg 17 Al 12 , while generating Al₄Ce phase with a higher thermal stability. The Al-Ce phase could hinder the grain-boundary sliding and migration and reduced the degree of plastic deformation of subsurface metal. Scanning electron microscopy observation showed that the surfacing AZ91 alloy with 1.5% Ce had a total of four types of wear mechanism: abrasion, oxidation, and severe plastic deformation were the primary mechanisms; delamination was the secondary mechanism.

  20. Characteristics of AZ31 Mg alloy joint using automatic TIG welding

    Science.gov (United States)

    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.

  1. RGDC Peptide-Induced Biomimetic Calcium Phosphate Coating Formed on AZ31 Magnesium Alloy

    Science.gov (United States)

    Cao, Lin; Wang, Lina; Fan, Lingying; Xiao, Wenjun; Lin, Bingpeng; Xu, Yimeng; Liang, Jun; Cao, Baocheng

    2017-01-01

    Magnesium alloys as biodegradable metal implants have received a lot of interest in biomedical applications. However, magnesium alloys have extremely high corrosion rates a in physiological environment, which have limited their application in the orthopedic field. In this study, calcium phosphate compounds (Ca–P) coating was prepared by arginine–glycine–aspartic acid–cysteine (RGDC) peptide-induced mineralization in 1.5 simulated body fluid (SBF) to improve the corrosion resistance and biocompatibility of the AZ31 magnesium alloys. The adhesion of Ca–P coating to the AZ31 substrates was evaluated by a scratch test. Corrosion resistance and cytocompatibility of the Ca–P coating were investigated. The results showed that the RGDC could effectively promote the nucleation and crystallization of the Ca–P coating and the Ca–P coating had poor adhesion to the AZ31 substrates. The corrosion resistance and biocompatibility of the biomimetic Ca–P coating Mg alloys were greatly improved compared with that of the uncoated sample. PMID:28772717

  2. Microstructures and tensile properties of submerged friction stir processed AZ91 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Fang Chai

    2015-09-01

    Full Text Available 6 mm thick AZ91 casting alloy plates were subjected to normal friction stir processing (NFSP, in air and submerged friction stir processing (SFSP, under water, and microstructures and tensile properties of the experimental materials were investigated. After FSP, the coarse microstructures in the as-cast condition are replaced by fine and equiaxed grains and the network-like eutectic β-Mg17Al12 phases disappear and are changed into particles pinned at the grain boundaries. SFSP results in further grain refinement in comparison with NFSP, and the average grain sizes of the NFSP and SFSP alloys are 8.4 ± 1.3 and 2.8 ± 0.8 µm, respectively. XRD results reveal that the intensity of β-Mg17Al12 diffraction peaks in the SFSP specimen decreases compared with NFSP. Due to significant grain refinement, the tensile strength and elongation of the SFSP AZ91 alloy are increased from 262 MPa and 18.9% for the NFSP material to 282 MPa and 25.4%, and the tensile strength (282 MPa is nearly three times that of the BM (105 MPa. SFSP is an effective approach to refine the grain size and enhance the tensile properties of AZ91 casting alloy.

  3. Study on fluidity of squeeze cast AZ91D magnesium alloy with different wall thicknesses

    Directory of Open Access Journals (Sweden)

    Chen Yun

    2014-03-01

    Full Text Available Rectangular cross-section specimens with different section thicknesses were prepared to study the influences of pouring temperature, mould temperature and squeeze velocity on the fluidity of squeeze cast AZ91D magnesium alloy by means of orthogonal test design method. The results show that pouring temperature, mould temperature and squeeze velocity can significantly affect the fluidity of magnesium alloy specimens with wall thickness no more than 4 mm, and the pouring temperature is the most influential factor on the fluidity of specimens with wall thickness of 1, 2 and 3 mm, while mould temperature is the one for specimens with wall thickness of 4 mm. Increasing pouring temperature between 700 °C and 750 °C is beneficial to the fluidity of AZ91D magnesium alloy, and increasing mould temperature significantly enhances the filling ability of thick (3 and 4 mm section castings. The fluidity of squeeze cast magnesium alloy increases with the increase of wall thickness. It is not recommended to produce magnesium alloy casting with wall thickness of smaller than 3 mm by squeeze cast process due to the poor fluidity. The software DPS was used to generate the regression model, and linear regression equations of the fluidity of squeeze cast AZ91D with different wall thicknesses are obtained using the test results.

  4. Mutations in non-acid patch residues disrupt H2A.Z's association with chromatin through multiple mechanisms.

    Directory of Open Access Journals (Sweden)

    Thomas J Wood

    Full Text Available The incorporation of histone variants into nucleosomes is a critical mechanism for regulating essential DNA-templated processes and for establishing distinct chromatin architectures with specialised functions. H2A.Z is an evolutionarily conserved H2A variant that has diverse roles in transcriptional regulation, heterochromatin boundary definition, chromosome stability and DNA repair. The H2A.Z C-terminus diverges in sequence from canonical H2A and imparts unique functions to H2A.Z in the yeast S. cerevisiae. Although mediated in part through the acid patch-containing M6 region, many molecular determinants of this divergent structure-function relationship remain unclear. Here, by using an unbiased random mutagenesis screen of H2A.Z alleles, we identify point mutations in the C-terminus outside of the M6 region that disrupt the normal function of H2A.Z in response to cytotoxic stress. These functional defects correlate with reduced chromatin association, which we attribute to reduced physical stability within chromatin, but also to altered interactions with the SWR and INO80 chromatin remodeling complexes. Together with experimental data, computational modelling of these residue changes in the context of protein structure suggests the importance of C-terminal domain integrity and configuration for maintaining the level of H2A.Z in nucleosomes.

  5. Lactancia materna, alimentación artificial y el primer contacto con azúcar

    Directory of Open Access Journals (Sweden)

    Fabian Calixto Fraiz

    2013-01-01

    Full Text Available Objetivo: Este estudio evaluó los cambios en el patrón de lactancia materna, alimentación artificial y en la introducción de azúcar en la dieta de niños de 0 a 36 meses, a través de dos estudios, con un intervalo de 13 años en la ciudad de Curitiba, Paraná, Brasil. Material y métodos: Poblaciones semejantes de una misma región geográfica fueron evaluadas a través de un cuestionario, en los años de 1993 y 2006, envolviendo, respectivamente, las madres de 180 y 94 niños. Introducción de azúcar en la dieta fue considerada precoz cuando ocurrió antes del 6º mes completo de vida. Los datos fueron analizados estadísticamente a través del test de qui-cuadrado y test exacto de Fisher (α= 0,05. Resultados: Hubo diferencias en la frecuencia del primer contacto con azúcar (p <0,001, que ocurrió en el primer mes de vida en 61,7% de los niños del primer estudio y en sólo 3,2% de los niños del segundo estudio. Hubo diferencias en el patrón de lactancia materna (p = 0,02, siendo la prevalencia de niños amamantados mayor en el segundo estudio. No fueron encontradas diferencias estadísticamente significativas en la prevalencia de uso de biberón, uso de biberón durante la noche y lactancia materna durante la noche, así como en el uso de biberón conteniendo azúcar. Conclusiones: Estos resultados indican que la lactancia materna puede, además de sus varias ventajas, también promover el aplazamiento de la introducción de azúcar en la dieta infantil. Nuevas investigaciones son necesarias para confirmar esta hipótesis.

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

    Directory of Open Access Journals (Sweden)

    Vidya Subramanian

    Full Text Available 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

  7. Effect of rolling temperature of the magnesium alloy AZ31B formability; Efeito da temperatura de laminacao na deformabilidade da liga de magnesio AZ31B

    Energy Technology Data Exchange (ETDEWEB)

    Catorceno, L.L.C.; Zimmermann, A.J.O.; Padilha, A.F., E-mail: litzy.catorceno@poli.usp.b [Universidade de Sao Paulo (DEMM/EP/USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Metalurgica e de Materiais

    2010-07-01

    The magnesium alloy AZ31B presents an interesting set of properties, which makes it potential candidate for applications in automotive and aeronautics. The main limitation of magnesium alloys is the low capacity of plastic forming at room temperature. The main motivation of this project is to understand and control the microstructure and crystallographic texture of magnesium alloys, to improve their formability. The effect of rolling temperature on the formability of the alloy was studied in this stage of the project. The alloy in the form of annealed and recrystallized sheets (2 mm thick) was deformed by rolling at four different temperatures: 25, 100, 200 and 250 deg C. The microstructural characterization was achieved using several complementary techniques of microstructural analysis, such as optical microscopy, scanning electron microscopy, X-ray analysis by energy dispersive, X-ray diffraction and microhardness. Results about the effect of rolling temperature on the alloy formability were presented and discussed. (author)

  8. Effects of sintering temperature on the corrosion behavior of AZ31 alloy with Ca–P sol–gel coating

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Bo [School of Materials Science and Engineering, Liaoning University of Technology, Jinzhou, Liaoning Province, 121001 (China); Shi, Ping, E-mail: p_shi@sohu.com [School of Materials Science and Engineering, Liaoning University of Technology, Jinzhou, Liaoning Province, 121001 (China); Wei, Donghua [School of Materials Science and Engineering, Liaoning University of Technology, Jinzhou, Liaoning Province, 121001 (China); E, Shanshan [School of Mathematics and Physics, Bohai University, Jinzhou, Liaoning Province, 121013 (China); Li, Qiang; Chen, Yang [School of Materials Science and Engineering, Liaoning University of Technology, Jinzhou, Liaoning Province, 121001 (China)

    2016-04-25

    To slow down the initial biodegradation rate of magnesium alloy, calcium phosphate (Ca–P) coatings were prepared on AZ31 magnesium alloy by a sol–gel technique. To study the effects of sintering temperature on microstructure, bonding strength and corrosion behavior of the coatings, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and an adhesive strength test were used to characterize the coatings. The corrosion resistance of the coatings was investigated by immersion test and electrochemical corrosion techniques in simulated body fluid (SBF) solution. It shows that the sol–gel coatings consist of Ca{sub 2}P{sub 2}O{sub 7}, mixture of Ca{sub 2}P{sub 2}O{sub 7}, Ca{sub 3}(PO{sub 4}){sub 2} and hydroxyapatite, and hydroxyapatite, by sintering respectively at 300 °C, 400 °C and 500 °C. There are major cracks on the coatings. The crack area portion on the coating and the bonding strength at the interface between the calcium phosphate coating and the bare AZ31 increases, and the corrosion resistance of the coated AZ31 in SBF decreases with increasing sintering temperatures from 300 °C to 500 °C. Based on our investigations, the corrosion resistance of the coated AZ31 in SBF depends mainly on the crack area portion on the coatings, rather than on the coating phase stability. - Highlights: • Ca–P coating was prepared on AZ31 alloy by a sol–gel technique. • Crack area portion in the coating increases with temperatures. • Bonding strength between Ca–P coating and substrate increases with temperatures. • Corrosion resistance of the coated AZ31 in SBF decreases with temperatures. • Corrosion resistance of the coated AZ31 depends mainly on the crack area portion.

  9. Differential deposition of H2A.Z in combination with histone modifications within related genes in Oryza sativa callus and seedling.

    Science.gov (United States)

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

    2017-01-01

    As a histone variant, H2A.Z is highly conserved among species and plays a significant role in diverse cellular processes. Here, we generated genome-wide maps of H2A.Z in Oryza sativa (rice) callus and seedling by combining chromatin immunoprecipitation using H2A.Z antibody and high-throughput sequencing. We found a significantly high peak and a small peak of H2A.Z distributed at the 5' and 3' ends of highly expressed genes, respectively. H2A.Z was also associated with inactive genes in both tissues. H3 lysine 4 trimethylation was associated with H2A.Z deposition at the 5' end of expressed genes, and H3 lysine 27 trimethylation peaks were partially associated with H2A.Z. In summary, our study provides global analysis data for the distribution of H2A.Z in the rice genome. Our results demonstrate that the differential deposition of H2A.Z might play important roles in gene transcription during rice development. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

  10. Correlative change of corrosion behavior with the microstructure of AZ91 Mg alloy modified with Y additions

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Ruiling, E-mail: jrl014014@163.com [College of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia 010051 (China); Zhang, Ming; Zhang, Lina [College of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia 010051 (China); Zhang, Wei [Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China); Guo, Feng [College of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia 010051 (China)

    2015-06-15

    Highlights: • The effect of Y addition into the AZ91 Mg alloys was investigated. • Initial stage of corrosion was studied by in-situ 3D digital microscopy observation. • The potential difference was investigated by Kelvin probe force microscopy. • The effect of Y addition on the corrosion mechanisms of AZ91 alloy was studied. - Abstract: Microstructure characterization of the AZ91 magnesium alloys with or without rare earth element yttrium (Y) has been revealed by SEM, EDS and EPMA. Some Y-rich phases can be found in the magnesium alloys with Y additions. The fraction of β-Mg{sub 17}Al{sub 12} phase obvious decreases and turns into granular distribution with the increase of Y addition instead of original wet distribution along grain boundaries. The results of the potentiodynamic polarization tests show that the corrosion resistance of AZ91 alloy is improved with appropriate Y additions. But an in-situ observation of 3D digital microscopy for the initial stage of corrosion of the magnesium alloy with 0.9%Y addition shows that Y-rich phases act as cathodic effect and the α phases in the vicinity of them acting as anode are corroded. So the additions of Y have a beneficial effect that can depress the overall corrosion of AZ91 alloy, whereas its harmful effect is related to Y-rich phases because they present the highest Volta potential difference from the adjacent matrix and they can drive galvanic corrosion.

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

    Science.gov (United States)

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

    2015-10-01

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

  12. Effect of thermal tempering on microstructure and mechanical properties of Mg-AZ31/Al-6061 diffusion bonding

    Energy Technology Data Exchange (ETDEWEB)

    Jafarian, Mojtaba [Young Researchers and Elite Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Rizi, Mohsen Saboktakin, E-mail: M.saboktakin@Pa.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 8415683111 (Iran, Islamic Republic of); Department of Industrial Engineering, Lenjan Branch, Islamic Azad University, Isfahan (Iran, Islamic Republic of); Jafarian, Morteza [Young Researchers and Elite Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Honarmand, Mehrdad [Department of Mechanical Engineering, Tiran Branch, Islamic Azad University, Isfahan (Iran, Islamic Republic of); Javadinejad, Hamid Reza; Ghaheri, Ali [Department of Materials Engineering, Isfahan University of Technology, Isfahan 8415683111 (Iran, Islamic Republic of); Department of Industrial Engineering, Lenjan Branch, Islamic Azad University, Isfahan (Iran, Islamic Republic of); Bahramipour, Mohammad Taghi [Materials Engineering Department, Hakim Sabzevari University, Sabzevar, 397 (Iran, Islamic Republic of); Ebrahimian, Marzieh [Department of Materials Engineering, Isfahan University of Technology, Isfahan 8415683111 (Iran, Islamic Republic of); Department of Industrial Engineering, Lenjan Branch, Islamic Azad University, Isfahan (Iran, Islamic Republic of)

    2016-06-01

    The objective of this study is to investigate the effect of the types thermal tempering of aluminum alloy on microstructure and mechanical properties of AZ31-O Mg and Al 6061-T6 diffusion bonding. Using Optical Microscope (OM) and Scanning Electron Microscopes (SEM) equipped with EDS analysis and line scan the interfaces of joints were evaluated. The XRD analysis was carried out to characterize phase constitution near the interface zone. The mechanical properties of joints were measured using Vickers micro-hardness and shear strength. According to the results in bonding of AZ31-Mg/Al-6061-O, in less plastic deformation in magnesium alloy, diffusion rate of most magnesium atoms occurred to aluminum alloy and formation of diffusion zone with minimum micro-hardness (140 HV) and maximum shear strength (32 MPa) compared to Al 6061-T6/Mg-AZ31 bonding. Evaluation of fracture surfaces indicates an occurrence of failure from the brittle intermetallic phases. - Highlights: • Diffusion bonding AZ31 to Al-6061withoutany interlayer was successful. • Thermal tempered aluminum alloy plays a vital role in the mechanical properties of joint. • Less thickness of reaction layers and micro-hardness in bonding annealed Al- 6061 layers to AZ31 was achieved. • Fracture surfaces indicated that the onset of fracture from intermetallic compounds resulted in fracture of the cleavage.

  13. interacción sporisorium scitamineum - caña de azúcar

    Directory of Open Access Journals (Sweden)

    Mar\\u00EDa La O- Hechavarr\\u00EDa

    2007-01-01

    Full Text Available Proteínas relacionadas con la defensa en la interacción Sporisorium scitamineum - caña de azúcar. El presente trabajo se realizó en el Centro Nacional de Sanidad Agropecuaria (CENSA, Habana, Cuba, durante el periodo 2001-2005, con el objetivo de determinar los patrones isoenzimáticos superóxido dismutasa y las secuencias de proteínas relacionadas con la defensa inducida en la interacción S. scitamineum - caña de azúcar, para lo cual fueron inoculadas con el patógeno las yemas de las variedades Ja60-5 (susceptible y M31/45 (resistente con una suspensión de esporidios del patógeno. La separación electroforética en condiciones nativas permitió la detección de dos isoformas ácidas de la enzima, una que se induce en mayor magnitud en la variedad resistente en comparación con la susceptible y otra que mantiene su nivel constitutivo para ambas variedades. El análisis ADNc-AFLP permitió la obtención de secuencias de PRs homólogas a glucanasas (PR2, quitinasas (PR3 y osmotina (PR5 inducidas diferencialmente en la variedad resistente. Los resultados obtenidos sugieren la participación de la enzima superóxido dismutasa en la señalización de la infección en esta interacción; así como la participación de PRs en la respuesta de resistencia inducida. Todo esto brinda la posibilidad de utilizar dichas proteínas como posibles marcadores bioquímicos y moleculares en Programas de Selección de Variedades Resistentes al Carbón de la Caña de Azúcar.

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

    Science.gov (United States)

    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. Copyright © 2011 AlphaMed Press.

  15. Artificial Neural Network Modelling of Vibration in the Milling of AZ91D Alloy

    Directory of Open Access Journals (Sweden)

    Ireneusz Zagórski

    2017-09-01

    Full Text Available The paper reports the results of artificial neural network modelling of vibration in. a milling process of magnesium alloy AZ91D by a TiAlN-coated carbide tool. Vibrations in machining processes are regarded as an additional, absolute machinability index. The modelling was performed using the so-called “black box” model. The best fit was determined for the input and output data obtained from the machining process. The simulations were performed by the Statistica software using two types of neural networks: RBF (Radial Basis Function and MLP (Multi-Layered Perceptron.

  16. Influence of mictrostructure features on the corrosion behaviourof AZ91 alloy in chloride media

    Directory of Open Access Journals (Sweden)

    Lenka Bukovinová

    2014-11-01

    Full Text Available The influence of the microstructure of as-cast AZ91 magnesium alloy, which applied to solution annealing treatment and ageing treatment respectively, was evaluated in terms of its corrosion behaviour in 0.1 M NaCl solution at room temperature. The corrosion process was monitored by electrochemical impedance spectroscopy (EIS and the surface was characterized by scanning Kelvin probe force microscopy (SKPFM. The extent of corrosion damage was dependent on the microstructure. Surface potential maps indicated that, the surface potential of α-matrix is more positive than surface potential of β phase.

  17. 5X reticle fabrication using MEBES multiphase virtual address and AZ5206 resist

    Science.gov (United States)

    Milner, Kathy S.; Chipman, Paul S.

    1991-03-01

    An alternative exposure strategy has been developed for the MEBES electron beam exposure system that enhances throughput and improves registration accuracy of 5X reticles. The Multi-Phase Virtual Address (MPVA) exposure strategy utilizes a voting technique to minimize scan related distortions while increasing writing address size thus decreasing the write time significantly over present methods. The resist chosen to evaluate this writing strategy was Hoechst AZ5206. The technique was evaluated to determine performance capabilities for mask registration, linewidth tolerance and uniformity, scan related error reduction and throughput improvements.

  18. Effect of cenospheres addition on microstructure and properties of AZ91D alloy

    OpenAIRE

    Zhi-qiu Huang; Si-rong Yu; Ming Hu

    2015-01-01

    The cenospheres/AZ91D composites were fabricated by melt stir method. The phases, microstructure and tensile fracture morphology of the composites were analyzed using XRD, Olympus metallurgical microscopy and SEM methods. The thermal expansion coefficient (CTE) and tensile properties were measured. The results showed that the cenospheres distribute uniformly in the Mg alloy matrix and refine the matrix microstructure. Mg2Si and MgO were found in addition to α-Mg and β-Mg17Al12 phases using XR...

  19. Conversion Coatings Produced on AZ61 Magnesium Alloy by Low-Voltage Process

    Directory of Open Access Journals (Sweden)

    Nowak M.

    2016-03-01

    Full Text Available The resultes of anodic oxide conversion coatings on wrought AZ61 magnesium alloy production are describe. The studies were conducted in a solution containing: KOH (80 g/l and KF (300 g/l using anodic current densities of 3, 5 and 10 A/dm2 and different process durations. The obtained coatings were examined under a microscope and corrosion tests were performed by electrochemical method. Based on these results, it was found that the low-voltage process produces coatings conferring improved corrosion resistance to the tested magnesium alloy.

  20. Fatigue behaviour of welded joints from magnesium alloy (AZ31) according to the local strain concept

    Energy Technology Data Exchange (ETDEWEB)

    Karakas, Oe.; Guelsoez, A. [Engineering Faculty, Department of Mechanical Engineering, University Pamukkale, Denizli (Turkey); Kaufmann, H.; Sonsino, C.M. [Fraunhofer - Institute for Structural Durability and System Reliability, LBF, Darmstadt (Germany)

    2010-02-15

    In the present study, the results of fatigue tests with the magnesium alloy AZ31 (ISO-MgAl3Zn1) in the material states base metal, heat affected zone and weld metal obtained under strain control at room temperature within a range from 2.10{sup 2} to 5 .10 {sup 6} cycles are presented. The fatigue behaviour was characterized by the Coffin-Manson-Basquin equations and the stress - strain behaviour by the Ramberg-Osgood equation. The data can be used to assess welded magnesium joints according to the local strain concept. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. El azúcar y el ejercicio físico: su importancia en los deportistas

    OpenAIRE

    Peinado Lozano, Ana Belen; Rojo Tirado, Miguel Angel; Benito Peinado, Pedro José

    2013-01-01

    El glucógeno muscular, principal almacén de glucosa en el organismo, y la glucemia sanguínea constituyen uno de los principales sustratos energéticos para la contracción muscular durante el ejercicio. El azúcar (sacarosa) es un estupendo suplemento al suministrar tanto glucosa como fructosa. Por ello, es esencial que los deportistas cuiden su alimentación, para mantener y aumentar los depósitos de este combustible, ya que las reservas de glucógeno muscular constituyen un factor limitante de l...

  3. Patria y nación en la época de Porfirio Díaz

    OpenAIRE

    Enrique Florescano

    2005-01-01

    El presente trabajo analiza las diversas visiones de la idea de Patria y Nación en la época de Porfirio Díaz. Las pinturas, litografías, monumentos patrióticos, narraciones históricas, entre otras expresiones; fungen como relatores de los orígenes e identidad nacional. Es importante destacar la representación evolutiva del pasado y la revaloración del mundo mesoamericano como ejemplo de la antigua nación indígena. Dentro de las celebraciones del Centenario de la Independencia s...

  4. Microstructure and mechanical properties of AZ91D alloy prepared by a semi-solid diecasting process

    Energy Technology Data Exchange (ETDEWEB)

    Du, X.H.; Wu, B.L. [Shenyang Inst. of Aeronautical Engineering, Shenyang (China). Dept. of Materials Engineering; Zhang, E.L. [Chinese Academy of Sciences, Shenyang (China). Inst. of Metal Research

    2007-03-15

    Semi-solid processing has been combined with die-casting for the magnesium alloy AZ91D. The microstructure of the semi-solid diecast AZ91D has been examined by optical microscopy and scanning electron microscopy. No pores were visible under optical microscopy, indicating a very low porosity. Mechanical properties of the semi-solid diecast AZ91D alloy have also been tested. High ultimate tensile strength and elongation have been achieved due to the low porosity and the fine microstructure. The fracture surfaces have been investigated by scanning electron microscopy in order to reveal the fracture mechanism. A typical inter-granular fracture surface was observed, indicating that the alloy fails in a brittle manner. The vertical-section microstructure of the fractured sample has indicated that the crack mainly propagates along the grain boundaries through the brittle fracture of the eutectic phase or the interface decohesion of the primary Mg phase and the eutectic phases. (orig.)

  5. The negative-difference effect during the localized corrosion of magnesium and of the AZ91HP alloy

    Directory of Open Access Journals (Sweden)

    Weber Cristina R.

    2003-01-01

    Full Text Available Galvanostatic tests with pure magnesium and with the AZ91HP alloy were performed in NaCl solutions, and the volume of hydrogen evolved during the tests was measured. In order to examine the negative-difference effect, a concept was developed to separate the hydrogen evolution (H.E. on the passive surface and the H.E. inside the pits. An analysis of the volumetric data showed that the current density of H.E. inside the pits is much higher for Mg than for the AZ91HP alloy. With the assumption, that the ratio between the hydrogen reduction rate and the rate of the anodic metal dissolution, expressed by the factor k, does not change with the polarization, a k value of ca. 0.5 for pure Mg was found, while for the AZ91HP alloy this value was only ca. 0.3.

  6. Correlation of Microstructure and Electrochemical Corrosion Behavior of Squeeze-Cast Ca and Sb Added AZ91 Mg Alloys

    Science.gov (United States)

    Bankoti, A. K. S.; Mondal, A. K.; Perugu, Chandra S.; Ray, B. C.; Kumar, S.

    2017-10-01

    The effect of individual and mixed additions of calcium (Ca) and antimony (Sb) on the corrosion behavior of the squeeze-cast AZ91 alloy have been investigated. The corrosion resistance of all modified alloys is better as a result of the refined and reduced volume fraction of the β-Mg17Al12 phase as well as grain refinement. Individual additions are better than mixed additions. The AZ91-1.0Ca (AZX911) alloy comprising individual Ca addition with a continuous network of the Al2Ca phase reveals the lowest corrosion rate. Among the alloys comprising combined additions, the AZ91-2.0Ca-0.3Sb (AZXY9120) alloy exhibits the best corrosion resistance because of the higher and lower volume fractions of the Al2Ca and Ca2Sb phases, respectively.

  7. Microstructure of fly ash cenosphere/AZ91D composite during solution treatment at 380-420℃

    Directory of Open Access Journals (Sweden)

    Huang Zhiqiu

    2011-02-01

    Full Text Available The fly ash cenosphere/AZ91D (FAC/AZ91D composites containing 5 wt.% and 100 µm in size of fly-ash cenosphere particles were fabricated by means of the compcasting method. The microstructures of the as-cast samples and the effect of the solution treatment at 380℃, 400℃, and 420℃ for 16 h on the microstructures of the samples were investigated by using of OM, SEM, XRD and EDS. The results showed that the cenospheres distributed homogeneously in the Mg alloy, and were almost filled with Mg alloy. The main interfacial phase between the cenospheres and AZ91D Mg alloy was identified as MgAl2O4 according to XRD, EDS and thermodynamic analysis. Mg2Si particles tended to be spheroidized via the solution treatment and the β phase (Mg17Al12 dissolved completely at 400℃.

  8. Mechanical properties and microstructural evaluation of AA1100 to AZ31 dissimilar friction stir welds

    Energy Technology Data Exchange (ETDEWEB)

    Azizieh, M., E-mail: azizieh@gmail.com [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Sadeghi Alavijeh, A. [School of Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Avenue, Surrey, BC V3T 0A3 (Canada); Abbasi, M. [High Temperature Energy Materials, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of); Balak, Z. [Department of Materials Science and Engineering, Ahvaz Branch, Islamic Azad University, Ahvaz (Iran, Islamic Republic of); Kim, H.S. [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2016-02-15

    In this paper, microstructure and mechanical properties of dissimilar friction stir welds of AA1100 and AZ31 were investigated to understand the effects of rotational and travel speed as well as pin position. The tensile results of welded samples revealed that the sound welds were formed when the stirring pin deviated from the centreline to the AZ31 side. The X-ray diffraction shows that Al{sub 3}Mg{sub 2} and Al{sub 12}Mg{sub 17} intermetallics formation occurs in the stir zone during the welding process. High hardness of these intermetallic phases increased the hardness of the stir zone to 110 Hv. The best tensile results were obtained in the sample processed in the range of 28–32 (rev/mm) rotational to travel speed ratio. - Highlights: • For Al to Mg friction stir welding, tool offset must be to Mg side. • There is an optimum rotational speed for obtain the highest strength. • Intermetallics form in any welding condition. • The volume fraction of intermetallic is directly related to FSW peak temperature.

  9. Dynamic recrystallization behavior of AZ31 magnesium alloy processed by alternate forward extrusion

    Science.gov (United States)

    Li, Feng; Liu, Yang; Li, Xu-Bo

    2017-09-01

    One of the important factors that affect the microstructure and properties of extruded products is recrystallization behavior. Alternate forward extrusion (AFE) is a new type of metal extrusion process with strong potential. In this paper, we carried out the AFE process experiments of as-cast AZ31 magnesium alloy and obtained extrusion bar whose microstructure and deformation mechanism were analyzed by means of optical microscopy, electron backscattered diffraction and transmission electron microscopy. The experimental results indicated that homogeneous fine-grained structure with mean grain size of 3.91 μm was obtained after AFE at 573 K. The dominant reason of grain refinement was considered the dynamic recrystallization (DRX) induced by strain localization and shear plastic deformation. In the 573-673 K range, the yield strength, tensile strength and elongation of the composite mechanical properties are reduced accordingly with the increase of the forming temperature. Shown as in relevant statistics, the proportion of the large-angle grain boundaries decreased significantly. The above results provide an important scientific basis of the scheme formulation and active control on microstructure and property for AZ31 magnesium alloy AFE process.

  10. Mechanical properties of homogenized twin-roll cast and conventionally cast AZ31 magnesium alloys

    Directory of Open Access Journals (Sweden)

    Mariia Zimina

    2015-02-01

    Full Text Available The improvement of mechanical properties of magnesium alloys nowadays is very important, because of the variety of industrial applications. For this goal, the number of casting techniques and further treatments were developed. Among the continuous casting techniques, which allow producing long strips of the alloys, is twin-roll casting. Using this process one can get the magnesium alloy with finest microstructure and higher specific strength. In this paper the comparison of tensile properties of conventionally cast and twin-roll cast AZ31 magnesium alloys was made. Tensile tests were carried out with constant strain rate 10-3 s-1 at temperatures ranging from 100 to 300 °C. Both materials were tested in as-cast state and after homogenization treatment at 450 °C for 10 hours. The investigation showed that there are no significant changes in ductility of AZ31 conventionally cast alloy even after heat treatment, while the ductility of twin-roll cast alloy increases.

  11. Influence of Friction Stir Welding on Mechanical Properties of Butt Joints of AZ61 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Seung-Ju Sun

    2017-01-01

    Full Text Available In this study, the effect of heat input on the mechanical properties and fracture behaviors of AZ61 magnesium alloy joints has been studied. Magnesium alloy AZ61 plates with thickness of 5 mm were welded at different ratios of tool rotational speed to welding speed (ω/ν. The average ultimate tensile strength of all weld conditions satisfying a ω/ν ratio of 3 reached 100% of the strength of the base material. Fractures occurred at the interface between the thermomechanical affected zone at advancing side and the stir zone in all welded specimens. From the scanning electron microscope and electron backscatter diffraction analysis, it was determined that the interface between the thermomechanical affected zone and the stir zone, which is the region where the grain orientation changes, was the weakest part; the advancing side region was relatively weaker than the retreating side region because the grain orientation change occurred more dramatically in the advancing side region.

  12. Numerical Simulation and Experiment Study on Extrusion of AZ31 Magnesium Alloy Tube

    Directory of Open Access Journals (Sweden)

    SUN Ying-di

    2017-06-01

    Full Text Available The extrusion process of typical AZ31 magnesium alloy tube was simulated by using the constitutive model of AZ31 alloys and ALE-based HyperXtrude software. The changes of stress distribution and velocity distribution were analyzed under different conditions, through the adjustment of three structural parameters, including the height, big round corner and gradient of weld chamber. The results show that the pressure near the work zone in the weld chamber decrease with the increase of the height of weld chamber, the maximum value and average value of the pressure in the weld chamber are decreasing with the increase of big round corner of weld chamber, and the pressure in the port holes and weld chamber increases with the increase of the gradient of weld chamber. The minimum variance of metal flow rate is achieved in the height of weld chamber with 16mm, big round corner with 18mm and gradient of weld chamber with 15°. The optimized structure alleviates the issues of stress concentration and non-homogeneous flowing velocity. The final die is proved to be capable of producing the qualified products and the microstructure after extrusion is uniform and fine.

  13. TiO2 Deposition on AZ31 Magnesium Alloy Using Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Leon White

    2013-01-01

    Full Text Available Plasma electrolytic oxidation (PEO has been used in the past as a useful surface treatment technique to improve the anticorrosion properties of Mg alloys by forming protective layer. Coatings were prepared on AZ31 magnesium alloy in phosphate electrolyte with the addition of TiO2 nanoparticles using plasma electrolytic oxidation (PEO. This present work focuses on developing a TiO2 functional coating to create a novel electrophotocatalyst while observing the surface morphology, structure, composition, and corrosion resistance of the PEO coating. Microstructural characterization of the coating was investigated by X-ray diffraction (XRD and scanning electron microscopy (SEM followed by image analysis and energy dispersive spectroscopy (EDX. The corrosion resistance of the PEO treated samples was evaluated with electrochemical impedance spectroscopy (EIS and DC polarization tests in 3.5 wt.% NaCl. The XRD pattern shows that the components of the oxide film include Mg from the substrate as well as MgO and Mg2TiO4 due to the TiO2 nanoparticle addition. The results show that the PEO coating with TiO2 nanoparticles did improve the corrosion resistance when compared to the AZ31 substrate alloy.

  14. Influence of second phase particles on fracture toughness in AZ31 magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, T.; Somekawa, H. [Dept. of Metallurgy and Materials Science, Osaka Prefecture Univ., Sakai (Japan); Takara, A.; Nishikawa, Y. [Matsushita Electric Industrial Co., Ltd., Osaka (Japan); Higashi, K. [Dept. of Metallurgy and Materials Science, Osaka Prefecture Univ., Sakai (Japan)

    2004-07-01

    Three kinds of thin AZ31 wrought magnesium alloys sheets were used in order to investigate the influence of the second phase particles on fracture toughness. From the theoretical model, the ratio of {lambda}{sub p}/d{sub p} would be estimated 5 {proportional_to} 6. On the other hand, from the microstructural observation, average particle spacing on each material was sample A: 13.1 {mu}m, sample B: 14.1, and sample C: 12 {mu}. In addition, average particle size on each sample was sample A: 2.1, sample B: 1.9, and sample C: 2.3 {mu}m. Therefore, the ratio of {lambda}{sub p}/d{sub p} calculated from fracture surface observation would be predicted 6 {proportional_to} 7. In comparison with the result of the prediction by theoretical analysis was in good agreement with the result of fracture toughness observation. It was found that the variation in plane-strain fracture toughness on AZ31 were affected by both of particle spacing and particle size. (orig.)

  15. El blocao (y el bloqueo de José Díaz Fernández

    Directory of Open Access Journals (Sweden)

    Luis Fernando Bueno Morillas

    2015-06-01

    Full Text Available El blocao (1928 fue la primera novela de José Díaz Fernández. Supuso un éxito editorial insólito hasta entonces porque reunía tres características novedosas: una actitud crítica ante la guerra de Marruecos, una integración de las novedades vanguardistas en la que su autor llamó literatura de avanzada y un posicionamiento del intelectual al lado de las reivindicaciones del pueblo. Sin embargo, aunque publicó otra novela un año después (La Venus mecánica, un libro teórico en el que definía la literatura que él propugnaba y practicaba (El nuevo romanticismo y algunas narraciones breves, Díaz Fernández se bloqueó y dejó la literatura narrativa que tan buenas expectativas levantó. Analizaremos las posibles causas de ese bloqueo.

  16. Geologie study off gravels of the Agua Fria River, Phoenix, AZ

    Science.gov (United States)

    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.

  17. Environmental friendly anodizing of AZ91D magnesium alloy in alkaline borate-benzoate electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yan [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Department of Chemistry, Tianshui Normal University, Tianshui 741000 (China); Wei Zhongling [Magnesium Technology Co., Ltd., Chinese Academy of Sciences, Jiaxing 314051 (China); Yang Fuwei [Department of Chemistry, Tianshui Normal University, Tianshui 741000 (China); Zhang Zhao, E-mail: eaglezzy@zjuem.zju.edu.cn [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Key Laboratory for Light Alloy Materials Technology, Jiaxing 314051 (China)

    2011-06-02

    Highlights: > Environmental friendly PEO technology for AZ91 magnesium alloy is developed. > NaBz is used as new additive and it is low-cost and environmental friendly. > The effect of NaBz additive on the properties of the anodized film was studied. > Anodized film with excellent corrosion resistance is obtained. > The forming mechanism of anodized film in the presence of NaBz is approached. - Abstract: A kind of environmental friendly anodizing routine for AZ91D magnesium alloy, based on an alkaline borate-sodium benzoate electrolyte (NaBz) was studied. The effect of NaBz on the properties of the anodized film was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), respectively. The results showed that the anodizing process, surface morphology, thickness, phase structure and corrosion resistance of the anodized film were strongly dependent on the concentration of NaBz. In the presence of adequate NaBz, a thick, compact and smoothing anodized film with excellent corrosion resistance was produced. Moreover, the forming mechanism of the anodized film in the presence of NaBz additive was also approached, which was a suppression of arc discharge process by the adsorption of Bz{sup -} on the surface of magnesium alloy substrate.

  18. EnviroAtlas - Phoenix, AZ - BenMAP Results by Block Group

    Science.gov (United States)

    This EnviroAtlas dataset demonstrates the effect of changes in pollution concentration on local populations in 2,434 block groups in Phoenix, AZ. The US EPA's Environmental Benefits Mapping and Analysis Program (BenMAP) was used to estimate the incidence of adverse health effects (i.e., mortality and morbidity) and associated monetary value that result from changes in pollution concentrations for Maricopa County, AZ. Incidence and value estimates for the block groups are calculated using i-Tree models (www.itreetools.org), local weather data, pollution data, and U.S. Census derived population data. This dataset was produced by the US Forest Service to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

  19. Electrophoretic deposition of nanostructured hydroxyapatite coating on AZ91 magnesium alloy implants with different surface treatments

    Energy Technology Data Exchange (ETDEWEB)

    Rojaee, Ramin, E-mail: raminrojaee@aim.com [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Raeissi, Keyvan [Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of)

    2013-11-15

    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 MgF{sub 2} conversion coating were exploited as surface pre-treatment of AZ91 magnesium alloy to generate a nanostructured hydroxyapatite (n-HAp) coating via electrophoretic deposition (EPD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) techniques were used to characterize the obtained powder and coatings. The potentiodynamic polarization tests were carried out to evaluate the corrosion behavior of the coated and uncoated specimens, and in vitro bioactivity evaluation were performed in simulated body fluid. Results revealed that the MAO/n-HAp coated AZ91 Mg alloy samples with a rough topography and lower corrosion current density leads to a lower Mg degradation rate accompanied by high bioactivity.

  20. Effects of filter materials on microstructure and mechanical properties of AZ91

    Directory of Open Access Journals (Sweden)

    Wu Guohua

    2010-11-01

    Full Text Available The present investigation studied the effects of different kinds of ceramic foam filters (CFF incorporating gas bubbling on the microstructure and mechanical properties of virgin AZ91 alloys, and the reactions between filters and Mg melt during filtration. The results show that the purification process of CFF incorporating gas bubbling process can obviously improve the Rm and A of AZ91 alloy, especially the A. Amongst the selected four kinds of CFF, the MgO filter is the most suitable for filtrating Mg melt, and the filtration effective sequence of four kinds of filtrating materials is as follows: MgO>Al2O3>ZrO2>SiC. With MgO filter incorporating gas bubbling treatment under Ar flow rate of 2 L/min and temperature of 730 °C, the ultimate tensile strength Rm and elongation A can be improved greatly from 175.3 MPa and 2.74% to 195.4 MPa and 4.54%, respectively. No inclusions are found on the fracture surface of the sample filtrated by MgO ceramic foam filter, and the fracture mode is quasi-cleavage crack.

  1. Tailoring degradation of AZ31 alloy by surface pre-treatment and electrospun PCL fibrous coating

    Energy Technology Data Exchange (ETDEWEB)

    Hanas, T. [Medical Materials Laboratory, Indian Institute of Technology Madras, Chennai 600036 (India); School of Nano Science and Technology, National Institute of Technology Calicut, Calicut, Kerala 673601 (India); Sampath Kumar, T.S., E-mail: tssk@iitm.ac.in [Medical Materials Laboratory, Indian Institute of Technology Madras, Chennai 600036 (India); Perumal, Govindaraj; Doble, Mukesh [Department of Biotechnology - Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036 (India)

    2016-08-01

    AZ31 magnesium alloy was coated with polycaprolactone (PCL) nano-fibrous layer using electrospinning technique so as to control degradation in physiological environment. Before coating, the alloy was treated with HNO{sub 3} to have good adhesion between the coating and substrate. To elucidate the role of pre-treatment and coating, samples only with PCL coating as well as HNO{sub 3} treatment only were prepared for comparison. Best coating adhesion of 4B grade by ASTM D3359–09 tape test was observed for pre-treated samples. The effect of coating on in vitro degradation and biomineralization was studied using supersaturated simulated body fluid (SBF 5 ×). The weight loss and corrosion results obtained by immersion test showed that the combination of HNO{sub 3} pre-treatment and PCL coating is very effective in controlling the degradation rate and improving bioactivity. Cytotoxicity studies using L6 cells showed that PCL coated sample has better cell adhesion and proliferation compared to uncoated samples. Nano-fibrous PCL coating combined with prior acid treatment seems to be a promising method to tailor degradation rate with enhanced bioactivity of Mg alloys. - Highlights: • PCL electrospun coating on HNO{sub 3} pre-treated AZ31 alloy controls biodegradation. • Acid pre-treatment stabilizes the substrate - coating interface. • Electrospun porous coating improves biomineralization. • Coating similar to extracellular matrix enhances cell adhesion.

  2. AZ ÖKOENERGIA-TURIZMUS LÉNYEGE ÉS JÖVÅ JE

    OpenAIRE

    David, Lorant; Baros, Zoltan; Bujdosó, Zoltán

    2006-01-01

    A megújuló energiaforrásokhoz kapcsolódó beruházások és létesítmények a világ számos részén -- elsősorban a szakértő közönséget vonzó -- turisztikai attrakcióvá váltak. Az üzemlátogatások és tájékoztatók amellett, hogy a szakembereknek kitűnő alkalmat adnak továbbképzésre és az újabb technológiai innovációk megismerésére, a téma oktatásában érdekelteknek és a laikusoknak is bemutatják a megújuló energiaforrások felhasználási lehetőségeit. A környezeti nevelés szempontjából fontos, hogy a megú...

  3. Microstructural developments and mechanical properties of friction stir welding of AZ91D magnesium alloy plates

    Directory of Open Access Journals (Sweden)

    Nagabhushan Kumar Kadigithala

    2017-06-01

    Full Text Available Friction stir welding (FSW is an efficient technique which can be used particularly for magnesium and aluminum alloys that are difficult to fusion weld. In this work AZ91D Mg alloy plates 3mm thick were friction stir welded at different process variables such as rotational speed and welding speed. The range of rotational speeds varied from 1025 to 1525 rpm, and the welding speed varied from 25 to 75 mm/min. Good quality welds were obtained under 1025 rpm of rotational speed with the welding speeds range from 25 to 75 mm/min. The microstructure of the AZ91D alloy consists of primary α-phase, eutectic α-phase and eutectic β (Mg17Al12 phase in the received condition (gravity die cast. The original dendrite grain structure completely disappeared and was transformed to fine equiaxed grains in stir zone (SZ. It was observed that there was a slight increase in hardness in SZ, because of fine recrystallized grain structure. The transverse tensile test results of weld specimens indicated constant strength irrespective of traveling speed. Fractrographic analysis of the friction stir welded specimens showed the brittle failure.

  4. Hot deformation characteristics of AZ80 magnesium alloy: Work hardening effect and processing parameter sensitivities

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Y.; Wan, L.; Guo, Z. H.; Sun, C. Y.; Yang, D. J.; Zhang, Q. D.; Li, Y. L.

    2017-02-01

    Isothermal compression experiment of AZ80 magnesium alloy was conducted by Gleeble thermo-mechanical simulator in order to quantitatively investigate the work hardening (WH), strain rate sensitivity (SRS) and temperature sensitivity (TS) during hot processing of magnesium alloys. The WH, SRS and TS were described by Zener-Hollomon parameter (Z) coupling of deformation parameters. The relationships between WH rate and true strain as well as true stress were derived from Kocks-Mecking dislocation model and validated by our measurement data. The slope defined through the linear relationship of WH rate and true stress was only related to the annihilation coefficient Ω. Obvious WH behavior could be exhibited at a higher Z condition. Furthermore, we have identified the correlation between the microstructural evolution including β-Mg17Al12 precipitation and the SRS and TS variations. Intensive dynamic recrystallization and homogeneous distribution of β-Mg17Al12 precipitates resulted in greater SRS coefficient at higher temperature. The deformation heat effect and β-Mg17Al12 precipitate content can be regarded as the major factors determining the TS behavior. At low Z condition, the SRS becomes stronger, in contrast to the variation of TS. The optimum hot processing window was validated based on the established SRS and TS values distribution maps for AZ80 magnesium alloy.

  5. Sealing of PEO Coated AZ91 Magnesium Alloy Using La-Based Solutions

    Directory of Open Access Journals (Sweden)

    Luca Pezzato

    2017-01-01

    Full Text Available In this work, solutions containing lanthanum salts were used for a post-treatment of sealing to increase the corrosion resistance of PEO coated AZ91 alloy. PEO coatings were produced on samples of AZ91 magnesium alloy using an alkaline solution containing sodium hydroxide, sodium phosphates, and sodium silicates. The sealing treatment was performed in a solution containing 12 g/L of La(NO33 at pH 4 at different temperatures and for different treatment times. Potentiodynamic polarization test, an EIS test, showed that the sealing treatment with solution containing lanthanum nitrate caused a remarkable increase in the corrosion resistance. The corrosion behavior was correlated with the surface morphology and elemental composition evaluated with scanning electron microscope (SEM, X-ray diffraction (XRD, and X-ray photoelectron spectroscopy (XPS. In particular, the sealing treatment at 50°C for 30 min resulted in being the most promising to increase the corrosion properties of PEO treated samples because of the formation of a homogeneous sealing layer, mainly composed of La(OH3.

  6. Fatigue characteristics of sand-cast AZ91D magnesium alloy

    Directory of Open Access Journals (Sweden)

    Zhenming Li

    2017-03-01

    Full Text Available The fatigue characteristics of the AZ91D-T6 alloy samples taken from engine blocks have been investigated at 20 °C and elevated temperature (150 °C. The fatigue strength and cyclic stress amplitude of the alloy significantly decrease with the increase of the test temperature, although cyclic hardening occurs continuously until failure for both temperatures. With the increase of the temperature, the decreased fatigue life of the alloy tested at the same stress amplitude is mainly attributed to the decreased matrix strength and the increased hysteresis energies. Fatigue failure of the engine blocks made of AZ91D-T6 alloy is mainly controlled by casting defects. For the defect-free specimens, the crack initiation behavior is determined by the single-slip (20 °C and by environment-assisted cyclic slip (150 °C during fatigue, respectively. The low-cycle fatigue lives of the alloy can be predicted using the Coffin-Manson relation and Basquin laws, the three-parameter equation and the energy-based concepts, while the high-cycle fatigue lives of the alloy fitted well with the developed long crack life model and MSF life models.

  7. A New Factor in American Destiny: Visions of Porfirio Díaz and the Politics of “Logical Paternalism”

    OpenAIRE

    Ruiz, Jason

    2011-01-01

    This essay interprets American representations of dictator Porfirio Díaz in relation to the “economic conquest” of Mexico that took place during his long rule (1876–1911, a period known as the “Porfiriato,” in which Americans invested more than $1 billion). No single person inspired as much attention from travelers, reporters, and photographers during the late nineteenth and early twentieth centuries as Díaz, and their visions of the President helped to shape perceptions of Mexico as a desira...

  8. CSER 96-014: criticality safety of project W-151, 241-AZ-101 retrieval system process test

    Energy Technology Data Exchange (ETDEWEB)

    Vail, T.S., Fluor Daniel Hanford

    1997-02-06

    This Criticality Safety Evaluation Report (CSER) documents a review of the criticality safety implications of a process test to be performed in tank 241-AZ-101 (101-AZ). The process test will determine the effectiveness of the retrieval system for mobilization of solids and the practicality of the system for future use in the underground storage tanks at Hanford. The scope of the CSER extends only to the testing and operation of the mixer pumps and does not include the transfer of waste from the tank. Justification is provided that a nuclear criticality is extremely unlikely, if not impossible, in this tank.

  9. SAFETY ANALYSIS FOR TANK 241-AZ-101 MIXER PUMP PROCESS TEST

    Energy Technology Data Exchange (ETDEWEB)

    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

  10. Variant histone H2A.Z is globally localized to the promoters of inactive yeast genes and regulates nucleosome positioning.

    Directory of Open Access Journals (Sweden)

    Benoît Guillemette

    2005-12-01

    Full Text Available H2A.Z is an evolutionary conserved histone variant involved in transcriptional regulation, antisilencing, silencing, and genome stability. The mechanism(s by which H2A.Z regulates these various biological functions remains poorly defined, in part due to the lack of knowledge regarding its physical location along chromosomes and the bearing it has in regulating chromatin structure. Here we mapped H2A.Z across the yeast genome at an approximately 300-bp resolution, using chromatin immunoprecipitation combined with tiling microarrays. We have identified 4,862 small regions--typically one or two nucleosomes wide--decorated with H2A.Z. Those "Z loci" are predominantly found within specific nucleosomes in the promoter of inactive genes all across the genome. Furthermore, we have shown that H2A.Z can regulate nucleosome positioning at the GAL1 promoter. Within HZAD domains, the regions where H2A.Z shows an antisilencing function, H2A.Z is localized in a wider pattern, suggesting that the variant histone regulates a silencing and transcriptional activation via different mechanisms. Our data suggest that the incorporation of H2A.Z into specific promoter-bound nucleosomes configures chromatin structure to poise genes for transcriptional activation. The relevance of these findings to higher eukaryotes is discussed.

  11. Influencia de compuestos azúcares y no azúcares en la calidad industrial de caña de azúcar en Tucumán (R. Argentina: Parte 1: caña limpia y despuntada Influence of sugar and nonsugar compounds on sugarcane industrial quality in Tucumán (Argentine Republic

    Directory of Open Access Journals (Sweden)

    B. Silvia Zossi

    Full Text Available Se estudió la concentración de compuestos azúcares y no azúcares, especialmente los que influyen en la formación del color y otros que inciden en el proceso industrial de producción de azúcar blanco directo, de las cuatro variedades comerciales de caña más difundidas en Tucumán (R. Argentina: TUCCP 77-42, LCP 85-384, CP 65-357 y RA 87-3. Estos ensayos fueron realizados durante las zafras 2004 a 2007 en caña limpia y despuntada. Los parámetros analizados fueron: extracción de jugo, Brix %, pol % en jugo y en caña, sacarosa y azúcar recuperable. Se estudiaron no azúcares inorgánicos, tales como cenizas, fosfato y sílice, y no azúcares orgánicos: fibra, almidón, compuestos antocianos y fenoles, nitrógeno amínico, ácidos cis y trans-aconítico, "indicator value" y color. De las cuatro variedades analizadas, la que mejor comportamiento presentó para producir azúcar blanco directo fue LCP 85-384, por su alto contenido en sacarosa y bajo contenido de componentes no azúcares. El segundo lugar le correspondió a la variedad RA 87-3, seguida por CP 65-357 y TUCCP 77-42.The concentration of sugar and nonsugar compounds, especially those which play a part in colour formation and others which affect direct white sugar manufacturing process, was studied in the four commercial cane varieties most widely grown in Tucumán (Argentine Republic: TUCCP 77-42, LCP 85-384, CP 65-357 and RA 87-3. Trials with clean cane were conducted during the 2004-2007 harvests. Analyzed parameters were: juice extraction, Brix %, pol % in juice and cane, sucrose and sugar recovery. Inorganic nonsugar compounds, such as ash, phosphate and silica, as well as organic ones, such as fibre, starch, anthocyanin and phenolic compounds, amino nitrogen, cis and trans-aconitic acids, indicator value and colour, were studied. Results showed that LCP 85-384 variety had the best factory performance to produce direct white sugar because of its high sucrose and low

  12. Analysis of the Deformability of Two-Layer Materials AZ31/Eutectic / Analiza Możliwości Odkształcania Plastycznego Materiału Dwuwarstwowego AZ31/Eutektyka

    Directory of Open Access Journals (Sweden)

    Mola R.

    2015-12-01

    Full Text Available The paper present the results of physical simulation of the deformation of the two-layered AZ31/eutectic material using the Gleeble 3800 metallurgical processes simulator. The eutectic layer was produced on the AZ31 substrate using thermochemical treatment. The specimens of AZ31 alloy were heat treated in contact with aluminium powder at 445°C in a vacuum furnace. Depending on the heating time, Al-enriched surface layers with a thickness of 400, 700 and 1100 μm were fabricated on a substrate which was characterized by an eutectic structure composed of the Mg17Al12 phase and a solid solution of aluminium in magnesium. In the study, physical simulation of the fabricated two-layered specimens with a varying thickness of the eutectic layer were deformed using the plane strain compression test at various values of strain rates. The testing results have revealed that it is possible to deform the two-layered AZ31/eutectic material at low strain rates and small deformation values.

  13. The extrusion of AZ-series magnesium alloys - extending the processing limits by hydrostatic extrusion; Erweiterung der Prozessgrenzen beim Strangpressen von Magnesiumknetlegierungen der AZ-Reihe durch das hydrostatische Strangpressverfahren

    Energy Technology Data Exchange (ETDEWEB)

    Swiostek, J. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Werkstofforschung

    2008-12-04

    The present study is concerned with the analysis of the influence of hydrostatic extrusion on the microstructural development and mechanical properties of extruded profiles of the AZ-series magnesium alloys. This work also deals with the correlation between the microstructure and resulting mechanical properties for the case extruded profiles. (orig.)

  14. AZ-101 Mixer Pump Demonstration and Tests Data Management Analysis Plan

    Energy Technology Data Exchange (ETDEWEB)

    DOUGLAS, D.G.

    2000-02-22

    This document provides a plan for the analysis of the data collected during the AZ-101 Mixer Pump Demonstration and Tests. This document was prepared after a review of the AZ-101 Mixer Pump Test Plan (Revision 4) [1] and other materials. The plan emphasizes a structured and well-ordered approach towards handling and examining the data. This plan presumes that the data will be collected and organized into a unified body of data, well annotated and bearing the date and time of each record. The analysis of this data will follow a methodical series of steps that are focused on well-defined objectives. Section 2 of this plan describes how the data analysis will proceed from the real-time monitoring of some of the key sensor data to the final analysis of the three-dimensional distribution of suspended solids. This section also identifies the various sensors or sensor systems and associates them with the various functions they serve during the test program. Section 3 provides an overview of the objectives of the AZ-101 test program and describes the data that will be analyzed to support that test. The objectives are: (1) to demonstrate that the mixer pumps can be operated within the operating requirements; (2) to demonstrate that the mixer pumps can mobilize the sludge in sufficient quantities to provide feed to the private contractor facility, and (3) to determine if the in-tank instrumentation is sufficient to monitor sludge mobilization and mixer pump operation. Section 3 also describes the interim analysis that organizes the data during the test, so the analysis can be more readily accomplished. Section 4 describes the spatial orientation of the various sensors in the tank. This section is useful in visualizing the relationship of the Sensors in terms of their location in the tank and how the data from these sensors may be related to the data from other sensors. Section 5 provides a summary of the various analyses that will be performed on the data during the test

  15. Effect of fiber laser parameters on laser welded AZ31B Magnesium alloys

    Directory of Open Access Journals (Sweden)

    Mat Salleh Naqiuddin

    2017-01-01

    Full Text Available Recently, the usage of Magnesium (Mg alloys has been hugely applied in the industrial application such as in automotive, marine, and electronic due to its advantages of recyclability and lightweight. This alloys required low heat input to be weld since it is easily evaporated due to the Magnesium Oxide (MgO at the surface and it also possesses lower melting point compared to steel. Laser welding is more convenient to weld Mg alloys due to its high power and lower heat input. AZ31B was selected since it has strong mechanical properties among others Mg alloys due to the major alloying elements; Aluminium (Al and Zinc (Zn. Low power fiber laser machine with wavelength of 900 nm was used in this experiment. The intention of this work was to investigate the effect of low power fiber laser parameters and effect of shielding gas on weld penetration and microstructure. Another aim in this work was to produce the joint for this thin sheets metal. Penetration depth and microstructure evaluation were emphasized in the analysis section. Bead-on-Plate (BOP and laser lap welding was conducted on AZ31B with thicknesses of 1.0 mm and 0.6 mm for feasibility study using pulsed wave (PW mode. Defocusing features was used in order to find better focal position, which has less occurrence of evaporation (underfill. The effect of different angle of irradiation was also investigated. Two types of shielding gases, Argon (Ar and Nitrogen (N2 were used in order to study the effect of shielding gas. Lastly, the effect of pulsed energy on penetration types and depth of BOP welded samples was investigated. Focus point was found at focal length of 156 mm with 393.75 μm. For BOP experiment, higher pulsed energy used contributes to melt through defect. Meanwhile, Ns shielding gas proved to be better shielding gas in laser welding the AZ31B. Higher angle of irradiation could reduce the underfill defect. Fillet Lap joint of similar metal was successfully done where 2.0 J of

  16. Effect of isothermal heat treatment on semi-solid microstructure of AZ91D magnesium alloy containing rare earth Gd

    Directory of Open Access Journals (Sweden)

    Yong Hu

    2015-01-01

    Full Text Available The AZ91D magnesium alloy containing rare earth Gd was prepared in this study, and the effect of semi-solid isothermal heat treatment on the microstructure of the alloy was investigated to obtain an optimum semi-solid structure. Results show that Gd can refine the microstructure of AZ91D magnesium alloy, and the optimum semi-solid AZ91D microstructure can be achieved by adding 1.5wt.% Gd. After treated at 585 °C for 30 min, the well distributed rose-shaped and near-spherical semi-solid microstructures of AZ91D+1.5wt.%Gd alloy can be obtained. The liquid phase of the semi-solid alloy consists of three components, namely, the molten pool, the “entrapped liquid” pool and the liner liquid film which separates two neighbor particles. The solid phase is composed of two phases, the primary α-Mg particles and the α-Mg phase formed in the second stage of solidification. With the increase of holding time, melting which causes the decrease of the primary α-Mg particle size is the dominant mechanism in the initial stage while coalescence and Ostwald ripening tend to be the principles later.

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

    Science.gov (United States)

    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.

  18. H2A.Z mediates different aspects of chromatin function and modulates flowering responses in Arabidopsis.

    Science.gov (United States)

    Jarillo, José A; Piñeiro, Manuel

    2015-07-01

    Eukaryotic organisms have canonical histones and a number of histone variants that perform specialized functions and confer particular structural properties to the nucleosomes that contain them. The histone H2A family comprises several variants, with H2A.Z being the most evolutionarily conserved. This variant is essential in eukaryotes and has emerged as a key player in chromatin function, performing an essential role in gene transcription and genome stability. During recent years, biochemical, genetic and genomic studies have begun to uncover the role of several ATP-dependent chromatin-remodeling complexes in H2A.Z deposition and removal. These ATPase complexes are widely conserved from yeast to mammals. In Arabidopsis there are homologs for most of the subunits of these complexes, and their functions are just beginning to be unveiled. In this review, we discuss the major contributions made in relation to the biology of the H2A.Z in plants, and more specifically concerning the function of this histone variant in the transition from vegetative to reproductive development. Recent advances in the understanding of the molecular mechanisms underlying the H2A.Z-mediated modulation of the floral transition, and thermosensory flowering responses in particular, are discussed. The emerging picture shows that plants contain chromatin-remodeling complexes related to those involved in modulating the dynamics of H2A.Z in other eukaryotes, but their precise biochemical nature remains elusive. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  19. Johannes Theunisz and 'Abd al-'Azīz: a friendship in Arabic Studies in Amsterdam, 1609-1610

    NARCIS (Netherlands)

    van Dalen, D.

    2016-01-01

    In the winter of 1609-1610, the Moroccan diplomat 'Abd al-'Azīz b. Muḥammad spent four months in the home of the Mennonite Hebraist and Arabist Jan Theunisz in Amsterdam. The written reflections of their discussions on religion and everyday matters present an extraordinary example of the shifting

  20. 78 FR 34403 - Notice of Availability of the Record of Decision for the Quartzsite Solar Energy Project, AZ

    Science.gov (United States)

    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 100-megawatt...

  1. Microstructure characteristics and effect of aging process on the mechanical properties of squeeze-cast AZ91 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Han, G.M. [Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Han, Z.Q., E-mail: zqhan@tsinghua.edu.cn [Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Luo, A.A. [Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210 (United States); Department of Integrated Systems Engineering, The Ohio State University, Columbus, OH 43210 (United States); Liu, B.C. [Key Laboratory for Advanced Materials Processing Technology (Ministry of Education), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); State Key Laboratory of Automotive Safety and Energy, Department of Automotive Engineering, Tsinghua University, Beijing 100084 (China)

    2015-08-25

    Highlights: • Characterization of three-dimensional morphologies of precipitates using AFM. • Quantitative microstructure of aged squeeze-cast AZ91 alloy. • The non-uniform continuous precipitation during aging of squeeze-cast AZ91 alloy. • The relationship between microstructure and property of aged squeeze-cast AZ91 alloy. - Abstract: Quantitative microstructure information is critical to modeling and prediction of mechanical properties of structural components. In this study, the microstructure characteristics of aged squeeze-cast AZ91 alloy were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) analyses. Particularly, a study of the three-dimensional morphology of continuous precipitation during heat treatment was carried out using a combination of TEM and AFM. The results showed that a typical precipitate consisted of three kinds of faces, namely, broad, side, and end faces. The precipitate also presented a lath-shaped morphology with lozenge ends. Combined SEM and TEM analyses revealed quantitative information on the sizes and area number densities of precipitates after aging at different temperatures with different times. In general, the length and width of precipitates increased more rapidly than thickness during aging. The area number density initially increased and then slowly decreased because of coarsening. Furthermore, a special microstructure characteristic of the non-uniform continuous precipitation during aging was investigated using electron probe microanalysis (EPMA). The relationship between hardness response and yield strength was established.

  2. A Study on Compressive Anisotropy and Nonassociated Flow Plasticity of the AZ31 Magnesium Alloy in Hot Rolling

    Directory of Open Access Journals (Sweden)

    Guoqiang Wang

    2014-01-01

    Full Text Available Effect of anisotropy in compression is studied on hot rolling of AZ31 magnesium alloy with a three-dimensional constitutive model based on the quadratic Hill48 yield criterion and nonassociated flow rule (non-AFR. The constitutive model is characterized by compressive tests of AZ31 billets since plastic deformations of materials are mostly caused by compression during rolling processes. The characterized plasticity model is implemented into ABAQUS/Explicit as a user-defined material subroutine (VUMAT based on semi-implicit backward Euler's method. The subroutine is employed to simulate square-bar rolling processes. The simulation results are compared with rolled specimens and those predicted by the von Mises and the Hill48 yield function under AFR. Moreover, strip rolling is also simulated for AZ31 with the Hill48 yield function under non-AFR. The strip rolling simulation demonstrates that the lateral spread generated by the non-AFR model is in good agreement with experimental data. These comparisons between simulation and experiments validate that the proposed Hill48 yield function under non-AFR provides satisfactory description of plastic deformation behavior in hot rolling for AZ31 alloys in case that the anisotropic parameters in the Hill48 yield function and the non-associated flow rule are calibrated by the compressive experimental results.

  3. 78 FR 60698 - Safety Zone, Lucas Oil Drag Boat Racing Series; Thompson Bay, Lake Havasu City, AZ.

    Science.gov (United States)

    2013-10-02

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone, Lucas Oil Drag Boat Racing Series; Thompson..., AZ for the Lucas Oil Drag Boat Racing Series. This temporary safety zone is necessary to provide... rulemaking (NPRM) with respect to this rule because the logistical details of the Lucas Oil Drag Boat Racing...

  4. Proportional Strength-Ductility Relationship of Non-SF6 Diecast AZ91D Eco-Mg Alloys

    Science.gov (United States)

    Kim, Shae K.

    SF6 gas has been generally used for Mg alloys during melting and casting as a cover gas. The use of SF6 gas, however, will be limited owing to its significant impact on global warming. Non-SF6 process during melting and casting in diecasting industry has been proved with Eco-Mg alloys by a simple addition of small amount of CaO into AZ91D and AM60B Mg alloys. This paper will show non-SF6 diecasting procedures for AZ91D Eco-Mg alloys. Cold-chamber and hot-chamber diecasting mass productions were performed by using a Toshiba 135-ton cold chamber and a Frech 200-ton hot chamber diecasting machines under CO2 atmosphere without SF6 gas. An emphasis will be on proportional strength and ductility relationship of Eco-Mg alloys, in part, due to a high-quality melt, refined grain size and Al2Ca second phase strengthening. Microstructures and mechanical properties of AZ91D Eco-Mg alloys will be evaluated in comparison with those of conventional AZ91D Mg alloy.

  5. Effect of pre-homogenizing treatment on microstructure and mechanical properties of hot-rolled AZ91 magnesium alloys

    Directory of Open Access Journals (Sweden)

    Liuwei Zheng

    2016-06-01

    Full Text Available To improve the homogeneity and rolling formability of as-cast AZ91 magnesium, the effects of pre-homogenizing treatment on microstructure evolution, deformation mechanism, mechanical properties and tensile fracture morphology of hot-rolled AZ91 magnesium alloy were studied. The results showed that the amount of coarse β-Mg17Al12 phase decreases dramatically, being distributed along the grain boundaries as small strips after homogenizing. Twining plays a dominant role in the deformation mechanism of AZ91 alloys in the experimental condition, while dynamic recrystallization (DRX considerably occurred in homogenized-rolled alloys, contributed to microstructure uniformity and β-Mg17Al12 phase precipitated refinement. The tensile strength of homogenized-rolled AZ91 alloys increases dramatically with elongation declining slightly in contrast to homogenized alloys. The fracture surface of homogenized-rolled specimen exhibits more ductile fracture with the manifestation of a large amount of dimples distributing higher density in matrix, while the micro cracks are prone to initiate around the Mg/Mg17Al12 phase interface and grain boundaries owing to the fragile interface bonding of two phases.

  6. The Status of Implementation of Good Manufacturing Practices (GMP) Shredded Fish Production in UMKM Az-Zahrah, Makassar

    Science.gov (United States)

    Latif, Rindam; Dirpan, Andi; Indriani, Sylvia

    2017-12-01

    Good manufacturing practices (GMP) describes the requirements that an industry should follow throughout the production process starting from sorting raw materials to handling final products. The purpose of this research is to disclose each phase of GMP in making shredded fish and to assess the status of the practices implemented by the UMKM Az-zahrah in producing its product. This descriptive study is conducted by doing interview with owner followed by observation and documentation of all activities related to the production process in order to assess the status of GMP applied by the UMKM Az-zahrah. In assessing the status, we referred to Permenperin RI No.75 / M-Ind / Per / 7/2010 and KBPOM regulation no. HK 03.1.23.04.12.22007 Year 2012. The findings indicate some deviation occurred when UMKM Az-zahrah implemented it, those are (1) there is a pet in production room (2) production employees are not yet wearing work uniform (3) production room has directly access to toilet (4) there is no health label about health and nutritional claims. The status of applied GMP in the UMKM Az-zahrah is at D level (less good) with rating IV.

  7. Effect of Mucin and Bicarbonate Ion on Corrosion Behavior of AZ31 Magnesium Alloy for Airway Stents

    Directory of Open Access Journals (Sweden)

    Yongseok Jang

    2014-08-01

    Full Text Available The biodegradable ability of magnesium alloys is an attractive feature for tracheal stents since they can be absorbed by the body through gradual degradation after healing of the airway structure, which can reduce the risk of inflammation caused by long-term implantation and prevent the repetitive surgery for removal of existing stent. In this study, the effects of bicarbonate ion (HCO3− and mucin in Gamble’s solution on the corrosion behavior of AZ31 magnesium alloy were investigated, using immersion and electrochemical tests to systematically identify the biodegradation kinetics of magnesium alloy under in vitro environment, mimicking the epithelial mucus surfaces in a trachea for development of biodegradable airway stents. Analysis of corrosion products after immersion test was performed using scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDX and X-ray diffraction (XRD. Electrochemical impedance spectroscopy (EIS was used to identify the effects of bicarbonate ions and mucin on the corrosion behavior of AZ31 magnesium alloys with the temporal change of corrosion resistance. The results show that the increase of the bicarbonate ions in Gamble’s solution accelerates the dissolution of AZ31 magnesium alloy, while the addition of mucin retards the corrosion. The experimental data in this work is intended to be used as foundational knowledge to predict the corrosion behavior of AZ31 magnesium alloy in the airway environment while providing degradation information for future in vivo studies.

  8. The effects of homogenization treatment on wear resistance of AZ61 magnesium alloy fabricated by extrusion-shear process

    Science.gov (United States)

    Hu, H.-J.; Ying, Y.-L.; OU, Z.-W.; Wang, X.-Q.

    2017-12-01

    Wear resistance of extrusion shear-processed AZ61 magnesium samples with as-cast state and homogenization treatment state has been studied by wear tests using pin-on-disc experiments under dry sliding conditions. Wear rates and friction coefficients between AZ61 magnesium alloy and GCr15 steel have been used to evaluate wear resistances of AZ61 magnesium alloys, and obtained from dry sliding with different frequencies and loads. Scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS) were used to analyze microstructures before and after the wear tests to find the wear mechanisms of AZ61 magnesium samples with as-cast state and homogenization treatment state. The wear resistances of the homogeneous state samples prepared by extrusion-shear process are close to those of as cast state, which are due to the little differences of microstructures. In addition, the wear mechanisms change from mild wear to severe wear with rise of exerted loads and reciprocating frequencies.

  9. 76 FR 15936 - Designation for the Owensboro, KY; Bloomington, IL; Iowa Falls, IA; Casa Grande, AZ; Fargo, ND...

    Science.gov (United States)

    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 AGENCY...

  10. 78 FR 43850 - Opportunity for Designation in Owensboro, KY; Bloomington, IL; Iowa Falls, IA; Casa Grande, AZ...

    Science.gov (United States)

    2013-07-22

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

  11. ARSENIC REMOVAL FROM DRINKING WATER BY ADSORPTIVE MEDIA. USEPA DEMONSTRATION PROJECT AT VALLEY VISTA, AZ FINAL PERFORMANCE EVALUATION REPORT

    Science.gov (United States)

    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...

  12. Arsenic Removal from Drinking Water by Adsorptive Media USEPA Demonstration Project at Rimrock AZ Final Performance Evaluation Report

    Science.gov (United States)

    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 ...

  13. 14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES Special Flight Rules i...

  14. 14 CFR Special Federal Aviation... - 2-Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false 2-Special Flight Rules in the Vicinity of 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...

  15. Microstructural evolution of die-cast and homogenized AZ91 Mg-alloys during dry sliding condition

    Directory of Open Access Journals (Sweden)

    Nagaraj M. Chelliah

    2017-03-01

    Full Text Available Microstructural evolution of die-cast and homogenized AZ91 Mg-alloys was investigated during dry sliding wear condition. Tribological tests were performed using a pin-on-disc (EN8 steel configuration with a normal load of 50 N at a constant sliding speed of 2.5 ms−1 under ambient environment. Delamination was recognized as a predominant wear mechanism in both of these materials. The die-cast AZ91 Mg-alloy exhibits lower coefficient of friction and higher wear rate. This can be ascribed to increase in the intensity of load bearing capacity of hard β-Mg17Al12 phase, and crack formation/de-cohesion at the interface between primary α-Mg and discontinuous β-Mg17Al12 phases. On the contrary, the homogenized AZ91 Mg-alloy experiences higher coefficient of friction and lower wear rate. The friction-induced microstructural evolution (supersaturated α-Mg to eutectic (α + β-Mg17Al12 tending to minimize the wear rate by providing barrier to material removal in the near surface region of homogenized AZ91 Mg-alloy. Therefore, experimental observation revealed that an inverse relationship exists between wear rate and coefficient of friction for the investigated materials. The analysis of worn surfaces and subsurfaces by electron microscopy provided evidence to delamination wear and microstructural evolution.

  16. 76 FR 51462 - Notice of Release of an Easement Restriction at Phoenix-Mesa Gateway Airport, Mesa, AZ

    Science.gov (United States)

    2011-08-18

    ... Gateway Airport, Mesa, AZ AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of Request to... acres of property abutting Phoenix-Mesa Gateway, Mesa, Arizona, from all conditions contained in a grant..., Phoenix-Gateway Airport Authority, 5835 S. Sossaman Road, Mesa, Arizona 85212, Telephone: (480) 988-7709...

  17. ARSENIC REMOVAL FROM DRINKING WATER BY ADSORPTIVE MEDIA USEPA DEMONSTRATION PROJECT AT VALLEY VISTA, AZ SIX-MONTH EVALUATION REPORT

    Science.gov (United States)

    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...

  18. ARSENIC REMOVAL FROM DRINKING WATER BY ADSORPTIVE MEDIA, USEPA DEMONSTRATION PROJECT AT RIMROCK, AZ, SIX-MONTH EVALUATION REPORT

    Science.gov (United States)

    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...

  19. Evaluation of microstructural effects on the corrosion behaviour of AZ91D magnesium alloy

    DEFF Research Database (Denmark)

    Ambat, Rajan; Aung, Naing Naing; Zhou, W.

    2000-01-01

    The effect of microconstituents on the corrosion and electrochemical behaviour of AZ91D alloy prepared by die-casting and ingot casting route has been investigated in 3.5% NaCl solution at pH 7.25. The experimental techniques used include constant immersion technique, in-situ corrosion monitoring......, and potentiodynamic polarisation experiments. Surface examination and analytical studies were carried out using optical and scanning electron microscopy, EDX and XRD. The corrosion behaviour of microconstituents namely primary alpha, eutectic alpha and beta phases was significantly different. Goring of aluminum...... phase offered marginally lower corrosion rate and better passivation compared with the ingot. In die-cast and ingot, hydrogen evolution took place preferentially on beta phase. XRD pattern of non-corroded and corroded surface revealed the removal of beta phase from alloy surface during corrosion...

  20. Effect of surface treatment on wear behavior of magnesium alloy AZ31

    Directory of Open Access Journals (Sweden)

    Y. Fouad

    2011-03-01

    Full Text Available In the present study, wear test has been performed on wrought magnesium alloy AZ31 samples. The test samples were in different conditions as; in the as cast alloy or after undergoing different surface treatment of the wrought alloy. The surface treatments included ball burnishing, swaging and shot peening. The shot peening is done at two main pressure loads; 0.1 and 0.3 bars, while other parameters are held constant. The test results show that the wear worst results were observed in the as cast sample at pressure load 0.3 bars, while the shot peening sample has the worst wear rate among all samples at pressure load of 0.1 bars. On the other hand, the hardness test showed that the swaged sample has the highest hardness value among all samples.

  1. HIGH STRAIN RATE BEHAVIOUR OF AN AZ31 + 0.5 Ca MAGNESIUM ALLOY

    Directory of Open Access Journals (Sweden)

    Josef Pešička

    2012-01-01

    Full Text Available The paper reports behaviour of magnesium alloy AZ31 (nominal composition 3 % Al - 1 % Zn – balance Mg with an addition of 0.5 wt. % Ca at high strain rates. Samples were prepared by the squeeze cast technology. Dynamic compression Hopkinson tests were performed at room temperature with impact velocities ranging from 11.2 to 21.9 m.s-1. A rapid increase of the flow stress and the strain rate sensitivity was observed at high strain rates. Transmission electron microscopy showed extremely high dislocation density and mechanical twins of two types. Adiabatic shear banding is discussed as the reason for the observed behaviour at high strain rates.

  2. Influence of processing on microstructure and mechanical properties of magnesium alloy AZ91

    Directory of Open Access Journals (Sweden)

    Libor Pantělejev

    2016-06-01

    Full Text Available This paper deals with differences of mechanical characteristics and fracture surface morphology of AZ91 magnesium alloy in extruded state and after subsequent equal channel angular pressing (ECAP. According to the results, the tensile properties were not controlled by grain size only as values of the tensile strength and 0.2 proof stress were similar for both alloys despite having average grain size 15.9 μm for the extruded alloy and 1.2 μm for the ECAPed alloy. In contrast, microhardness seemed to be dependnt solely on the grain size. Fractographic analysis has shown changes in the damage mode from quasi-cleavage fracture in extruded state to rather ductile fracture with dimple morphology in exECAPed state during tensile loading.

  3. Data acquisition and PV module power production in upgraded TEP/AzRISE solar test yard

    Science.gov (United States)

    Bennett, Whit E.; Fishgold, Asher D.; Lai, Teh; Potter, Barrett G.; Simmons-Potter, Kelly

    2017-08-01

    The Tucson Electric Power (TEP)/University of Arizona AzRISE (Arizona Research Institute for Solar Energy) solar test yard is continuing efforts to improve standardization and data acquisition reliability throughout the facility. Data reliability is ensured through temperature-insensitive data acquisition devices with battery backups in the upgraded test yard. Software improvements allow for real-time analysis of collected data, while uploading to a web server. Sample data illustrates high fidelity monitoring of the burn-in period of a polycrystalline silicon photovoltaic module test string with no data failures over 365 days of data collection. In addition to improved DAQ systems, precision temperature monitoring has been implemented so that PV module backside temperatures are routinely obtained. Weather station data acquired at the test yard provides local ambient temperature, humidity, wind speed, and irradiance measurements that have been utilized to enable characterization of PV module performance over an extended test period

  4. En memoria de un científico mexicano: Francisco Díaz Covarrubias

    OpenAIRE

    Hermosillo-Villalobos, Juan J.

    1989-01-01

    Texto en torno al ingeniero y científico mexicano Francisco Díaz Covarrubias en conmemoración al centenario de su deceso. Covarrubias cursó la carrera de ingeniero topógrafo en el Colegio de Minería en la Ciudad de México, recibiendo los máximos horones en 1853. Algunas de sus principales aportaciones fueron el levantamiento de un Atlas del Valle de México, la fundación y su trabajo como director del Observatorio Astronómico Nacional, y la realización de la expedición a Japón en diciembre de ...

  5. Mechanical properties of high-pressure die-casting AZ91 magnesium alloy

    Directory of Open Access Journals (Sweden)

    K.N. Braszczyńska-Malik

    2008-12-01

    Full Text Available Results of mechanical properties of high-pressure die-casting AZ91 magnesium alloy are presented. Performed examinations allowed to determine influence of plunger velocity in the first and second stage and intensification pressure on the ultimate tensile strength (UTS, yield strength (YS, elongation (A5 and Agt, Brinell hardness (HB and impact strength (IS of samples cast on 320 tone cold chamber machine. Obtained results revealed the highest properties at median used parameters and also the most powerful effect of plunger velocity in the first stage. The maximum values of mechanical properties obtained from the performed experiments were: UTS 250 MPa, YS 160 MPa, A5 7%, 70 HB, IS 7 J.

  6. Effect of cenospheres addition on microstructure and properties of AZ91D alloy

    Directory of Open Access Journals (Sweden)

    Zhi-qiu Huang

    2015-11-01

    Full Text Available The cenospheres/AZ91D composites were fabricated by melt stir method. The phases, microstructure and tensile fracture morphology of the composites were analyzed using XRD, Olympus metallurgical microscopy and SEM methods. The thermal expansion coefficient (CTE and tensile properties were measured. The results showed that the cenospheres distribute uniformly in the Mg alloy matrix and refine the matrix microstructure. Mg2Si and MgO were found in addition to α-Mg and β-Mg17Al12 phases using XRD. The CTE of the composites reduced after the cenospheres are added. The yield strength of the composites increases significantly with an increase in the mass fraction and a decrease in the size of the cenospheres. The tensile strength of the composites achieves maximum when the mass fraction of cenospheres is 9wt.% and the size of cenospheres is 80 μm. The fracture mechanism of the composites is cleavage fracture.

  7. Corrosion of magnesium alloy AZ31 screws is dependent on the implantation site

    Energy Technology Data Exchange (ETDEWEB)

    Willbold, E. [Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Strasse 1-7, D - 30625 Hannover (Germany); Kaya, A.A. [Mugla University, Engineering Faculty, Metallurgy and Materials Engineering Department, Mugla (Turkey); Kaya, R.A. [MedicalPark Hospital, Kueltuer Sok No:1, 34160 Bahcelievler, Istanbul (Turkey); Beckmann, F. [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Str.1, D - 21502 Geesthacht (Germany); Witte, F., E-mail: witte.frank@mh-hannover.de [Laboratory for Biomechanics and Biomaterials, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Strasse 1-7, D - 30625 Hannover (Germany)

    2011-12-15

    The corrosion of biodegradable materials is a crucial issue in implant development. Among other materials, magnesium and magnesium based alloys are one of the most promising candidates. Since the corrosion of biodegradable materials depends on different physiological parameters like pH or ion concentrations, the corrosion might be different in different biological environments. To investigate this issue, we produced screws from magnesium alloy AZ31 and implanted them into the hip bone of 14 sheep. After 3 and 6 months, the screws were explanted and analyzed with synchrotron-radiation based micro-computed tomography and hard tissue histology. We found considerable differences in the corrosion behavior of the magnesium screws with respect to its original tissue location. However, we could detect a normal immunological tissue response.

  8. Chitosan coatings crosslinked with genipin for corrosion protection of AZ31 magnesium alloy sheets.

    Science.gov (United States)

    de Y Pozzo, Ludmila; da Conceição, Thiago F; Spinelli, Almir; Scharnagl, Nico; Pires, Alfredo T N

    2018-02-01

    In this study, coatings of chitosan crosslinked with genipin were prepared on sheets of AZ31 magnesium alloy and their corrosion protection properties were characterized by means of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The coatings were also characterized by means of FTIR and XPS. It was observed that the crosslinking process decreases the corrosion current and shifts the corrosion potential of the alloy to less negative values. The EIS analysis demonstrated that the crosslinking process increases the maximum impedance after short and long exposure times. The superior performance of the crosslinked coatings is related to a lower degree of swelling, as observed in the swelling tests carried out on free-standing films. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Influence of inorganic acid pickling on the corrosion resistance of magnesium alloy AZ31 sheet

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Blawert, C.; Scharnagl, N.

    2009-01-01

    the corrosion resistance of the alloy. The cleaning efficiency of the three acids used and the corrosion protection mechanisms were found to be remarkably different. Best corrosion results were obtained with nitric acid, followed closely by phosphoric acid. Only the sulphuric acid failed more or less when......Surface contaminants as a result of thermo-mechanical processing of magnesium alloys, e.g. sheet rolling, can have a negative effect on the corrosion resistance of magnesium alloys. Especially contaminants such as Fe, Ni and Cu, left on the surface of magnesium alloys result in the formation...... of micro-galvanic couples and can therefore increase corrosion attack on these alloys. Due to this influence they should be removed to obtain good corrosion resistance. In this study, the effect of inorganic acid pickling on the corrosion behaviour of a commercial AZ31 magnesium alloy sheet...

  10. Durability of AZ31 magnesium biodegradable alloys polydopamine aided: Part 1

    Directory of Open Access Journals (Sweden)

    Tullio Monetta

    2017-12-01

    Full Text Available The use of magnesium alloys, as a biodegradable medical device, is an interesting challenge for the biomaterials field. Its rapid degradation and the release of hydrogen, when exposed to biological fluids, are the main drawbacks for clinical applications. In this work, a coating made of polydopamine (PDOPA, is used as an intermediate layer to decrease the degradation rate of AZ31 magnesium alloy/polymeric coating system, when exposed to Hank's solution. Experimental results highlighted: (i the formation of a thin PDOPA layer, (ii an increased adhesion in the organic coating/metallic substrate system, (iii a decrease of two orders of magnitude of the corrosion rate when the PDOPA film is used together with an external organic coating, (iv the efficacy in the use of PDODA due to the synergistic effect of both, physical and chemical, interactions between the PDOPA layer and the organic coating.

  11. Comparison of Electrochemical Methods for the Evaluation of Cast AZ91 Magnesium Alloy

    Science.gov (United States)

    Tkacz, Jakub; Minda, Jozef; Fintová, Stanislava; Wasserbauer, Jaromír

    2016-01-01

    Linear polarization is a potentiodynamic method used for electrochemical characterization of materials. Obtained values of corrosion potential and corrosion current density offer information about material behavior in corrosion environments from the thermodynamic and kinetic points of view, respectively. The present study offers a comparison of applications of the linear polarization method (from −100 mV to +200 mV vs. EOCP), the cathodic polarization of the specimen (−100 mV vs. EOCP), and the anodic polarization of the specimen (+100 mV vs. EOCP), and a discussion of the differences in the obtained values of the electrochemical characteristics of cast AZ91 magnesium alloy. The corrosion current density obtained by cathodic polarization was similar to the corrosion current density obtained by linear polarization, while a lower value was obtained by anodic polarization. Signs of corrosion attack were observed only in the case of linear polarization including cathodic and anodic polarization of the specimen. PMID:28774046

  12. Simulation of cylindrical cup drawing of AZ31 sheet metal with crystal plasticity finite element method

    Science.gov (United States)

    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.

  13. A two-step superplastic forging forming of semi-continuously cast AZ70 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Pan Wang

    2015-03-01

    Full Text Available A two-step technology combined forging with superplastic forming has been developed to enhance the forgeability of semi-continuously cast AZ70 magnesium alloy and realize the application of the as-cast magnesium alloy in large deformation bullet shell. In the first step, fine-grained microstructure preforms that are suitable for superplastic forming were obtained by reasonably designing the size of the initial blanks with the specific height-to-diameter ratio, upsetting the blanks and subsequent annealing. In the second step, the heat treated preforms were forged into the end products at the superplastic conditions. The end products exhibit high quality surface and satisfied microstructure. Consequently, this forming technology that not only avoids complicating the material preparation but also utilizes higher strain rate superplastic provides a near net-shaped novel method on magnesium forging forming technology using as-cast billet.

  14. Initial deposition mechanism of electroless nickel plating on AZ91D magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Song, Y.; Shan, D.; Han, E. [Chinese Academy of Sciences, Environmental Corrosion Center, Inst. of Metal Research, Shenyang (China)

    2006-04-15

    The pretreatment processes and initial deposition mechanism of electroless nickel plating on AZ91D magnesium alloy were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The results showed that alkaline cleaning could remove the greases and oils from the substrate surface. Acid etching could wipe off the metal chippings and oxides. The hydrofluoric acid activating process which could improve the adhesion of coating to substrate played a key role in the subsequent process of electroless nickel plating. The nickel coating was deposited preferentially on the primary {alpha} phase and then spread to the eutectic {alpha} phase and {beta} phase. The nickel initially nucleated on the primary {alpha} phase by a replacement reaction, then grew depending on the autocatalysis function of nickel. The coating on the {beta} phase displayed better adhesion than that on the {alpha} phase due to the nails fixing effect. (author)

  15. Grain boundary sliding mechanism during high temperature deformation of AZ31 Magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Roodposhti, Peiman Shahbeigi, E-mail: pshahbe@ncsu.edu [North Carolina State University (United States); University of Connecticut (United States); Sarkar, Apu; Murty, Korukonda Linga [North Carolina State University (United States); Brody, Harold [University of Connecticut (United States); Scattergood, Ronald [North Carolina State University (United States)

    2016-07-04

    High temperature tensile creep tests were conducted on AZ31 Magnesium alloy at low stress range of 1–13 MPa to clarify the existence of grain boundary sliding (GBS) mechanism during creep deformation. Experimental data within the GBS regime shows the stress exponent is ~2 and the activation energy value is close to that for grain boundary diffusion. Analyses of the fracture surface of the sample revealed that the GBS provides many stress concentrated sites for diffusional cavities formation and leads to premature failure. Scanning electron microscopy images show the appearances of both ductile and brittle type fracture mechanism. X-ray diffraction line profile analysis (based on Williamson-Hall technique) shows a reduction in dislocation density due to dynamic recovery (DRV). A correlation between experimental data and Langdon's model for GBS was also demonstrated.

  16. Alelopatía en Saccharum spp. (caña de azúcar

    Directory of Open Access Journals (Sweden)

    R. A. Arévalo

    2011-01-01

    6 Aminoácidos no proteicos, 7 Lactonas no saturadas, 8 ácidos orgánicos, alcoholes alifáticos, aldehídos y cetonas, 9 ácidos grasos, naftoquinonas, antraquinonas, y complejos de quinonas, 10 Coumarina. Los mecanismos de acción en la mayoría de los aleloquímicos son aún desconocidos. Las plantas arvenses, como Cypro-Cyperus rotundus L.; Rooex-Rottboellia exaltata L. f. causan alelopatía en caña de azúcar. Las plantas de Cucsa- Cucumis sativus L. son afectadas por efectos alelopáticos de plantas de Rooex. Las coberturas utilizadas en la agricultura sostenible tienen propiedades alelopáticas. Las respuestas de las plantas cultivadas a los aleloquímicos pueden ser susceptibles, tolerantes o resistentes. La alelopatía tiene gran potencial para el manejo de plagas en la agricultura.

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

    Science.gov (United States)

    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.

  18. Effect of surface nanocrystallization on the microstructural and corrosion characteristics of AZ91D magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Laleh, M., E-mail: laleh.m.1992@gmail.com [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Kargar, Farzad, E-mail: farzad.kargar@gmail.com [Department of Materials Engineering, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of)

    2011-09-15

    Highlights: > Nanostructured surface layers were produced on AZ91D magnesium alloy by using SMAT. > Thickness of the deformed layer increased with increasing of the balls size. > Top surface microhardness for all of the SMATed samples increased significantly. > SMAT increased the surface roughness; increase in balls diameter increased the roughness. > SMAT using 2 mm balls increased the corrosion resistance significantly. - Abstract: Surface distinct deformed layers with thicknesses up to 150 {mu}m, with grain size in the top most surface is in the nanometer scale, were produced on AZ91D magnesium alloy using surface mechanical attrition treatment (SMAT). Effects of different ball size on the properties of the SMATed samples were investigated. The microstructural, grain size, hardness and roughness features of the treated surfaces were characterized using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-indenter and digital roughness meter, respectively. Corrosion behavior of the samples was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. It is found that the ball diameter does not have a significant effect on the top surface grain size, but the thickness of the deformed layer increases with increase of ball size, from 50 {mu}m for 2 mm balls to 150 {mu}m for 5 mm balls. For all of the SMATed samples, the top surface microhardness value increased significantly and did not show any obvious change for samples treated with different balls. Corrosion studies show that the corrosion resistance of the sample treated with 2 mm balls is higher than that of those treated with 3 mm and 5 mm balls. This can be mainly attributed to the surface roughness and defects density of the samples, which are higher for the SMATed samples with 3 mm and 5 mm balls compared with that of sample SMATed with 2 mm balls.

  19. Software configuration management plan, 241-AY and 241-AZ tank farm MICON automation system

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Archaeological studies at Drill Hole U20az Pahute Mesa, Nye county, Nevada. [Contains bibliography

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. The libertarian educational proposals of José Cabrera Díaz Las propuestas educativas libertarias de José Cabrera Díaz

    Directory of Open Access Journals (Sweden)

    Manuel FERRAZ LORENZO

    2013-09-01

    Full Text Available The purpose of this article is to explain the operational guidelines of the Canarian workers movement in the early Twentieth Century in connection with integral educational proposals. For this purpose, we have taken advantage of the articles published in the press by on of the leading exponents of the movement, a member of the anarchist school of thought, José Cabrera Diaz, whose curriculum vitae indicates his importance. He was a journalist, trades union leader and an outand- out defender of rationalist education and of the creation of people's schools, the purpose of which was to eradicate —by combating illiteracy and ignorance— the abusive quasi-feudal practices of the «caciques» that existed in the Canarian Archipiélago.El objetivo de este artículo consiste en exponer las líneas de trabajo del movimiento obrero en Canarias a comienzos de siglo, en lo concerniente a sus propuestas educativas de tipo integral. Para ello nos hemos servido de los trabajos publicados en prensa de uno de sus máximos representantes, inserto en la corriente de pensamiento anarquista: José Cabrera Díaz, cuyo curriculum lo dice todo. Periodista, líder sindical y, además, defensor a ultranza de la educación racionalista y de la creación de escuelas populares, destinadas a erradicar —desde la alfabetización y cultura— las prácticas caciquiles existentes en el Archipiélago.

  2. Cytotoxicity studies of AZ31D alloy and the effects of carbon dioxide on its biodegradation behavior in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiali, E-mail: wangjialicsu@yahoo.cn [Center for Translational Medicine Research and Development, Institute of Biomedical and Health Engineering, Chinese Academy of Sciences, Shenzhen 518055 (China); Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR (China); Qin, Ling [Center for Translational Medicine Research and Development, Institute of Biomedical and Health Engineering, Chinese Academy of Sciences, Shenzhen 518055 (China); Musculoskeletal Research Laboratory, Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR (China); Wang, Kai [School of Humanities and Social Sciences, Hunan University of Chinese Medicine, Changsha 410208 (China); Wang, Jue; Yue, Ye [Center for Translational Medicine Research and Development, Institute of Biomedical and Health Engineering, Chinese Academy of Sciences, Shenzhen 518055 (China); Li, Yangde [Guangdong Innovation Team for Biodegradable Magnesium and Medical Implants, E-ande, Dongguan 523660 (China); Tang, Jian [Center for Translational Medicine Research and Development, Institute of Biomedical and Health Engineering, Chinese Academy of Sciences, Shenzhen 518055 (China); Li, Weirong [Guangdong Innovation Team for Biodegradable Magnesium and Medical Implants, E-ande, Dongguan 523660 (China)

    2013-10-01

    Magnesium alloys have been advocated as potential artificial bone materials due to their biocompatibility and biodegradability. The understanding of their corrosive mechanism in physiological environments is therefore essential for making application-orientated designs. Thus, this in vitro study was designed to assess the effects of CO{sub 2} on corrosive behavior of AZ31D to mimic in vivo special ingredient. Electrochemical technologies accompanied with Scanning electron microscope, Fourier transform infrared, X-ray diffraction, Energy dispersive spectroscopy and hydrogen evolution measurement were employed to analyze corrosive rates and mechanisms of AZ31D. Moreover, the biocompatibility of AZ31D was assessed with a direct cell attachment assay and an indirect cytotoxicity test in different diluted extracts. The ion concentrations in extracts were measured using inductively coupled plasma mass spectrometry to offer explanations on the differences of cell viability in the indirect test. The results of the direct cytotoxicity assay showed that the corrosive rate of AZ31D was too rapid to allow for cell adhesion. Extracts diluted less than 20 times would cause adverse effects on cell proliferation, likely due to excessive ions and gas release. Moreover, the presence of CO{sub 2} did not cause significant differences on corrosive behavior of AZ31D according to the results of electrochemical testing and hydrogen evolution measurement. This might be caused by the simultaneous process of precipitation and dissolution of MgCO{sub 3} due to the penetration role of CO{sub 2}. This analysis of corrosive atmospheres on the degradation behavior of magnesium alloys would contribute to the design of more scientific in vitro testing systems in the future. - Highlights: • We evaluate the effects of CO{sub 2} on corrosion behavior of magnesium alloys. • We assess the feasibility of commercial AZ31D alloy as potential implants. • CO{sub 2} is not the key factor to minimize

  3. Determinación de azúcares reductores totales en jugos mezclados de caña de azúcar utilizando el método del ácido 3,5 dinitrosalicílico

    OpenAIRE

    Daniel Bello Gil; Emilia Carrera Bocourt; Yuset Díaz Maqueira

    2006-01-01

    Se desarrolló un procedimiento para determinar la concentración de azúcares reductores totales en jugos mezclados de caña de azúcar por el método del ácido 3,5 dinitro salicílico (DNS). Se evaluaron dos procedimientos para la preparación del reactivo del DNS: en frío y en caliente. Se realizó un análisis comparativo con el método de Eynon- Lane para diferentes diluciones del jugo. El método del DNS en frío mostró menores desviaciones que el método de Eynon-Lane y que el método del DNS en cali...

  4. Coordinated Lab, Field, and Aerial Studies of the Painted Desert, AZ, as a Potential Analog Site for Phyllosilicates at Mawrth Vallis, Mars

    Science.gov (United States)

    McKeown, N. K.; Noe Dobrea, E. Z.; Bishop, J. L.; Silver, E. A.

    2009-03-01

    One hypothesis for clay formation at Mawrth Vallis is an altered ash-fall, like bentonites in the Painted Desert, AZ. We compare lab, field, and aerial data to determine if silicate spectral features are accurately captured in aerial datasets.

  5. Los amargos beneficios del dulce. Azúcar, Cuba y deuda ecológica

    Directory of Open Access Journals (Sweden)

    Rodrigo y Alharilla, Martín

    2006-06-01

    Full Text Available This article is placed within the paradigm of environmental history. From a focus that is both macrohistorical and inductive, it offers a reflection upon the link between the deforestation registered in Cuba as a result of the expansion of sugar cane cultivation, and the transfer of part of the gains produced by sugar towards economies in other latitudes, particularly towards Catalonia. The study analyzes first of all the establishment of sugar cane “haciendas” in the old Cuban province of Las Villas during the second third of the 19th century. It then inquires into the life trajectory of several “hacienda” owners of the region, who in the last period of their lives settled down in Catalonia, where they transferred a large part of the capital they had accumulated on the island. Finally, the essay points at evidence that suggests that the proposed analysis may be applied to other regions in Cuba as well as to Puerto Rico.

    El artículo se situa en el paradigma de la historia ambiental. A partir de un enfoque a la vez microhistórico e inductivo, ofrece una reflexión sobre el vínculo existente entre la deforestación registrada en Cuba por efecto de la expansión del cultivo de la caña de azúcar y la transferencia de parte de las ganancias producidas por el azúcar a economías de otras latitudes, particularmente hacia Cataluña. Se analiza, en primer lugar, el proceso de implantación de las haciendas cañeras en la antigua provincia cubana de Las Villas, durante el segundo tercio del siglo XIX, y, a continuación, la trayectoria vital de varios hacendados de la región, los cuales acabaron instalándose en la etapa final de su vida en Cataluña, adonde trasladaron buena parte de los capitales acumulados en la isla. Por último, se apuntan diferentes evidencias que sugieren que el análisis planteado podría realizarse igualmente para otras regiones de Cuba así como para Puerto Rico.

  6. Evaluation of self-healing ability of Ce–V conversion coating on AZ31 magnesium alloy

    Directory of Open Access Journals (Sweden)

    Xiao Jiang

    2016-09-01

    Full Text Available This study investigated the influence of cerium nitrate in vanadate solutions on the properties of Ce–V conversion coatings on AZ31 magnesium alloys, and evaluated the self-healing behavior of the Ce–V conversion coating for AZ31 magnesium alloy. The results showed that the additions of cerium nitrate prevented pentavalent vanadium from reducing to tetravalent vanadium in the coatings during conversion reaction process. Adding appropriate cerium nitrate to vanadate solution led to a thicker coating with a more compact CeVO4 layer. The corrosion behavior of the Ce–V conversion coating was investigated by the electrochemical tests and the scratch immersion test in 3.5 wt.% NaCl solution. The self-healing ability of the coating was confirmed from all tests. The surface analysis revealed that the self-healing effect of the Ce–V conversion coating was only provided by the release and migration of vanadium compounds.

  7. Application of heat treatment and hot extrusion processes to improve mechanical properties of the AZ91 alloy

    Directory of Open Access Journals (Sweden)

    T. Reguła

    2010-04-01

    Full Text Available The main aim of this paper is to evaluate the effects of hot working (extrusion and hest treatment on room temperature mechanical properties of magnesium-based AZ91 alloy. The results were compared with as-cast condition. The examined material had been obtained by gravity casting to permanent moulds and subsequently subjected to heat treatment and/or processed by extrusion at 648 K. Microstructural and mechanical properties of properly prepared specimens were studied. Rm, Rp02 and A5 were determined from tensile tests. Brinell hardness tests were also conducted. The research has shown that hot working of AZ91 alloy provides high mechanical properties unattainable by cast material subjected to heat-treatment. The investigated alloy subjected to hot working and subsequently heat-treated has doubled its strength and considerably improved the elongation - compared with the as-cast material.

  8. Electrochemical Performance Estimation of Anodized AZ31B Magnesium Alloy as Function of Change in the Current Density

    Science.gov (United States)

    Girón, L.; Aperador, W.; Tirado, L.; Franco, F.; Caicedo, J. C.

    2017-08-01

    The anodized AZ31B magnesium alloys were synthesized via electrodeposition processes. The aim of this work was to determine the electrochemical behavior of magnesium alloys by using anodized alloys as a protective coating. The anodized alloys were characterized by x-ray diffraction, exhibiting the crystallography orientation for Mg and MgO phases. The x-ray photoelectron spectroscopy was used to determine the chemical composition of anodized magnesium alloys. By using electrochemical impedance spectroscopy and Tafel curves, it was possible to estimate the electrochemical behavior of anodized AZ31B magnesium alloys in Hank's balanced salt solution (HBSS). Scanning electron microscopy was performed to analyze chemical changes and morphological surface changes on anodized Mg alloys due to the reaction in HBSS/anodized magnesium surface interface. Electrochemical behavior in HBSS indicates that the coatings may be a promising material for biomedical industry.

  9. Influence of Accumulative Roll Bonding on the Texture and Tensile Properties of an AZ31 Magnesium Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Zuzanka Trojanová

    2018-01-01

    Full Text Available Deformation behaviour of rolled AZ31 sheets that were subjected to the accumulative roll bonding was investigated. Substantially refined microstructure of samples was achieved after the first and second pass through the rolling mill. Sheets texture was investigated using an X-ray diffractometer. Samples for tensile tests were cut either parallel or perpendicular to the rolling direction. Tensile tests were performed at temperatures ranging from room temperature up to 300 °C. Tensile plastic anisotropy, different from the anisotropy observed in AZ31 sheets by other authors, was observed. This anisotropy decreases with an increasing number of rolling passes and increasing deformation temperature. Grain refinement and texture are the crucial factors influencing the deformation behaviour.

  10. Mathematical Modeling of the Twin Roll Casting Process for AZ31 Magnesium Alloy - Effect of Set-Back Distance

    Science.gov (United States)

    Hadadzadeh, Amir; Wells, Mary; Essadiqi, Elhachmi

    A 2-D coupled thermal-fluid-stress model was developed and used to simulate the twin roll casting (TRC) of an AZ31 magnesium alloy using the commercial software package, ALSIM. The model was used to predict the fluid flow, temperature distribution and mechanical behavior of AZ31 magnesium alloy in the roll bite. An important parameter in controlling the TRC process is the set-back distance; the distance between the nozzle entry to the kissing point of the rolls. There are two approaches to increase the set-back: 1) increasing the entry thickness and 2) decreasing the final strip thickness. In this study the effect of set-back distance and casting speed on the thermo-mechanical behavior of the strip during TRC has been studied. The thermo-mechanical behavior of the strip has a significant effect on the final quality as defect formation depends on such behavior.

  11. Prediction of Cutting Conditions in Turning AZ61 and Parameters Optimization Using Regression Analysis and Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Nabeel H. Alharthi

    2018-01-01

    Full Text Available All manufacturing engineers are faced with a lot of difficulties and high expenses associated with grinding processes of AZ61. For that reason, manufacturing engineers waste a lot of time and effort trying to reach the required surface roughness values according to the design drawing during the turning process. In this paper, an artificial neural network (ANN modeling is used to estimate and optimize the surface roughness (Ra value in cutting conditions of AZ61 magnesium alloy. A number of ANN models were developed and evaluated to obtain the most successful one. In addition to ANN models, traditional regression analysis was also used to build a mathematical model representing the equation required to obtain the surface roughness. Predictions from the model were examined against experimental data and then compared to the ANN model predictions using different performance criteria such as the mean absolute error, mean square error, and coefficient of determination.

  12. Simulation of Flow Stress Characteristic During Two-stage Hot Deformation Process in AZ31B Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    DENG Xiaohu

    2017-06-01

    Full Text Available A 2-D CA model has been developed to simulate two-stage hot deformation processing of magnesium (Mg alloy. Based on the fact that Mg has an HCP crystal structure with six-fold symmetry, the model employs hexagonal CA lattice. The physically-based model has integrated the effects of individual metallurgical phenomena related with the hot deformation, including dynamic recrystallization (DRX, static recovery, static recrystallization (SRX, meta-dynamic recrystallization (MDRX and grain growth, etc. The model is validated by simulating single-stage and two-stage hot compression tests of AZ31B. The effects of temperature, strain rate, the interval and pre-strain on stress-strain curves are investigated. The calculated results are compared with the available experimental findings in AZ31B Mg alloy, and the simulated results agree well with the experimental results and theoretical models.

  13. PHYSICAL CHARACTERIZATION OF VITREOUS STATE LABORATORY AY102/C106 AND AZ102 HIGH LEVEL WASTE MELTER FEED SIMULANTS (U)

    Energy Technology Data Exchange (ETDEWEB)

    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).

  14. Systematic understanding of corrosion behavior of plasma electrolytic oxidation treated AZ31 magnesium alloy using a mouse model of subcutaneous implant

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Yongseok [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC, 27411 (United States); Tan, Zongqing [Internal Medicine, College of Medicine, University of Cincinnati, OH 45211 (United States); Jurey, Chris [Luke Engineering, Wadsworth, OH 44282 (United States); Collins, Boyce [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC, 27411 (United States); Badve, Aditya [Business and Biology, The University of North Carolina at Chapel Hill, NC 27514 (United States); Dong, Zhongyun [Internal Medicine, College of Medicine, University of Cincinnati, OH 45211 (United States); Park, Chanhee; Kim, Cheol Sang [Department of Bio-nano System Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Sankar, Jagannathan [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC, 27411 (United States); Yun, Yeoheung, E-mail: yyun@ncat.edu [Engineering Research Center for Revolutionizing Metallic Biomaterials (ERC-RMB), North Carolina A and T State University, Greensboro, NC, 27411 (United States)

    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. - Highlights: • Effects of plasma electrolytic oxidation on AZ31 in vitro and in vivo • Retardation of degradation via plasma electrolytic oxidation in vitro and in vivo • Differentiation of in vitro and in vivo corrosion types and products.

  15. Lysobacter capsici AZ78 produces cyclo(L-Pro-L-Tyr), a 2,5-diketopiperazine with toxic activity against sporangia of Phytophthora infestans and Plasmopara viticola.

    Science.gov (United States)

    Puopolo, G; Cimmino, A; Palmieri, M C; Giovannini, O; Evidente, A; Pertot, I

    2014-10-01

    To investigate low molecular weight compounds produced in vitro by Lysobacter capsici AZ78 and their toxic activity against sporangia of plant pathogenic oomycetes. Assays carried out in vitro showed that L. capsici AZ78 drastically inhibits the growth of plant pathogenic oomycetes. Accordingly, the preventive application of culture filtrates of L. capsici AZ78 on grapevine and tomato plants reduced the infections, respectively, caused by Plasmopara (Pl.) viticola and Phytophthora infestans. The subsequent chemical analysis of the culture filtrates of L. capsici AZ78 by spectroscopic (essentially 1D and 2D (1)H NMR and (13)C NMR and ESI MS spectra) and optical methods led to the identification of the 2,5-diketopiperazine cyclo(L-Pro-L-Tyr) that inhibited the development of P. infestans sporangia in vitro and on tomato leaves. Furthermore, a genomic region with high sequence identity with genes coding for a hybrid polyketide synthase and nonribosomal peptide synthetase was detected in L. capsici AZ78. Lysobacter capsici AZ78 produces cyclo(L-Pro-L-Tyr) in vitro that was effective in killing the sporangia of P. infestans and Pl. viticola in vitro. Moreover, this low molecular weight compound prevents the occurrence of late blight lesions when applied on tomato leaves. The application of L. capsici AZ78 cells or its own culture filtrates effectively controls both P. infestans and Pl. viticola. Cyclo(L-Pro-L-Tyr) produced by L. capsici AZ78 is toxic against sporangia of both these oomycetes. These data enforce the potential in the use of Lysobacter members for the control of plant pathogenic oomycetes and provide the basis for the development of new low-impact fungicides based on cyclo(L-Pro-L-Tyr). © 2014 The Society for Applied Microbiology.

  16. Evaluación de la mezcla de ametrina + clomazone en caña de azúcar

    Directory of Open Access Journals (Sweden)

    Valent\\u00EDn A. Esqueda

    2001-01-01

    Full Text Available caña de azúcar. Se estableció un experimento en el Rancho Casablanca, Municipio de Puente Nacional, en el estado de Veracruz, México, para evaluar la toxicidad ocasionada por la mezcla de los herbicidas ametrina + clomazone a las variedades de caña de azúcar MEX-79-431, MEX-69-290, MEX-68- P23 y CP-72-2086. Se evaluaron cuatro tratamientos de control de malezas: 1. Ametrina + clomazone (1200 + 800 g/ha, 2. Ametrina + clomazone (1800 + 1200 g/ha, 3. Ametrina + 2,4-D (1225 + 650 g/ha y 4. Testigo limpio. Los herbicidas se aplicaron cuando la caña de azúcar tenía entre dos y cuatro hojas. La mezcla de ametrina + clomazone ocasionó blanqueamiento del follaje en todas las variedades de caña de azú- car. El área con blanqueamiento, varió entre el 36,3 y 47,5% con la dosis mas alta de esta mezcla; entre el 25 y 39,4%, con la dosis menor y prácticamente desapareció a los 45 días despu és de la aplicación. A su vez, la mezcla de ametrina + 2,4- D no ocasionó blanqueamiento. La toxicidad ocasionada por la mezcla de ametrina + clomazone no afectó el número de hojas por planta, el número de tallos en 2 m lineales y la altura de las plantas. Tampoco fueron afectados el rendimiento de tallos y el contenido de sacarosa

  17. In vitro degradation, hemolysis, and cytocompatibility of PEO/PLLA composite coating on biodegradable AZ31 alloy.

    Science.gov (United States)

    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. © 2014 Wiley Periodicals, Inc.

  18. Magnesium alloy AZ63A reinforcement by alloying with gallium and using high-disperse ZrO2 particles

    Directory of Open Access Journals (Sweden)

    J. Khokhlova

    2016-12-01

    Full Text Available The aim of this work was to obtain an experimental magnesium alloy by remelting standard AZ63A alloy with addition of gallium ligatures and ZrO2 particles. This allowed reinforcement of alloy and increase its hardness and Young's modulus. The chemical analysis of this alloy shows two types of structures which are evenly distributed in volume. Thus we can conclude that reinforcing effect is the result of formation of intermetallic phase Mg5-Ga2.

  19. Analysis of the microstructure and deformation mechanisms by compression along normal direction in a rolled AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Dewen [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Liu, Tianmo, E-mail: tmliu@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chen, Huicong; Shi, Dongfeng; Ran, Chunhua; Pan, Fusheng [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China)

    2016-04-13

    The twinning and slipping modes of a rolled AZ31 magnesium alloy sheet were investigated through in situ compressive tests. A method based on scanning electron microscopy and electron backscattered diffraction measurements was used to identify activated twinning and slip systems. {10-12} tensile twins were present, but only occasionally. Contraction twins were not observed. Post deformation examination revealed the dominance of pyramidal slip.

  20. En híbrida mezcolanza: Exile and Cultural Anxiety in Alirio Díaz Guerra’s Lucas Guevara

    Directory of Open Access Journals (Sweden)

    Jeffrey Browitt

    2005-03-01

    Full Text Available The novel Lucas Guevara, written by the Colombian exile, Alirio Díaz Guerra, was first published in New York in 1914. It is considered to be the earliest novel about Latin American immigration to the United States written in Spanish. This fact alone merits its study. A second edition was published in 2001 along with a critical-biographical introduction, which presents the novel as the precursor of a developing genre of Hispanic immigrant literature centred on the naïve Latin American migrant who arrives in the United States inspired by the opportunities which the metropolis supposedly affords, but who nevertheless suffers a series of misfortunes because of the inability to adapt to the new culture. On the level of overt content, the novel is a lachrymose, stereotypical and conventional denunciation of the supposed evils of an amoral US society and the libertine and materialistic values underpinning it. But on a much deeper level, a picture emerges of Díaz Guerra himself as a displaced, disenchanted intellectual exile who suffers (or has suffered an acute cultural and class anxiety in the transition from a patrician Arcadia to the heart of capitalist, industrial modernity. Through a reading of the narrative voice, and by extension the implied author, we witness his difficult coming to terms with a highly-charged New York society (in comparison to his homeland, not only because of the sexual liberation brought on by secular modernization, but also because of the close proximity of volatile, eroticised bodies on the over-crowded Lower East Side of New York, the scene of the novel and Díaz Guerra’s point of entry into the United States. The novel also provides an occasion to contrast how Díaz Guerra deals with the condition of exile, in contrast to that most emblematic of Latin American political refugees, José Martí.

  1. A New Factor in American Destiny: Visions of Porfirio Díaz and the Politics of “Logical Paternalism”

    Directory of Open Access Journals (Sweden)

    Jason Ruiz

    2011-12-01

    Full Text Available This essay interprets American representations of dictator Porfirio Díaz in relation to the “economic conquest” of Mexico that took place during his long rule (1876–1911, a period known as the “Porfiriato,” in which Americans invested more than $1 billion. No single person inspired as much attention from travelers, reporters, and photographers during the late nineteenth and early twentieth centuries as Díaz, and their visions of the President helped to shape perceptions of Mexico as a desirable field in which to expand US capitalism and influence. Travelers clamored to meet him and his sophisticated young wife, and their travelogues were rich with descriptions of such encounters. Reporters, dazzled by the rapid transformation of Mexico during his 35-year rule, described Díaz in such terms as “the Mexican Wizard” and “the maker of modern Mexico” until the very end of his regime. Photographers, working in a relatively new medium, amassed a huge body of works devoted to the dictator; even at an advanced age late in his rule, the President’s image adorned postcards and commemorative cartes-de-visite that posited him in heroic and hypermasculine terms (not unlike those of his US counterpart, Theodore Roosevelt. Ultimately, this essay argues that representations like these reflected American desires for a Mexican body politic that was amenable to economic and social transformation under the inextricable banners of “progress” and US capitalism. Prevailing images of Díaz and his family suggested that Mexico was as friendly to foreign investors as it was to foreign visitors.

  2. Grain refinement of AZ91D alloy by intensive melt shearing and its persistence after remelting and isothermal holding

    Directory of Open Access Journals (Sweden)

    Zuo Yubo

    2013-01-01

    Full Text Available Intensive melt shearing has a significant grain refining effect on some light alloys. However, the persistence of the grain refining effect during isothermal holding and remelting is still unclear, although it is very important for the practical application. In this study, intensive melt shearing was achieved in a twin-screw mechanism to investigate its grain refining effect on AZ91D magnesium alloy. The refinement mechanism was discussed and the persistence of grain refinement after remelting and isothermal holding was also studied. A Zeiss imaging system with polarized light was used for quantitative measurement of grain size. The results show that the intensive melt shearing has a significant grain refining effect on AZ91D magnesium alloy. With the application of intensive melt shearing, the grain size of AZ91D magnesium alloy can be reduced from 530 μm (for a typical as-cast microstructure to 170 μm, which is about 70% size reduction. The grain refinement achieved by the intensive melt shearing can be partially kept after isothermal holding and remelting. It is believed that the refinement effect was mainly due to the finer and well dispersed oxide particles formed by high intensive shearing. The smaller size of oxide particles and their slow motion velocity in the sheared melt could make important contributions to the remained grain refinement.

  3. Investigation on the Effect of Pulsed Energy on Strength of Fillet Lap Laser Welded AZ31B Magnesium Alloys

    Science.gov (United States)

    Salleh, M. N. M.; Ishak, M.; Aiman, M. H.; Idris, S. R. A.; Romlay, F. R. M.

    2017-09-01

    AZ31B magnesium alloy have been hugely applied in the aerospace, automotive, and electronic industries. However, welding thin sheet AZ31B was challenging due to its properties which is easily to evaporated especially using conventional fusion welding method such as metal inert gas (MIG). Laser could be applied to weld this metal since it produces lower heat input. The application of fiber laser welding has been widely since this type of laser could produce better welding product especially in the automotive sectors. Low power fiber laser was used to weld this non-ferrous metal where pulse wave (PW) mode was used. Double fillet lap joint was applied to weld as thin as 0.6 mm thick of AZ31B and the effect of pulsed energy on the strength was studied. Bond width, throat length, and penetration depth also was studied related to the pulsed energy which effecting the joint. Higher pulsed energy contributes to the higher fracture load with angle of irradiation lower than 3 °

  4. Microstructure and corrosion characteristics of laser-alloyed magnesium alloy AZ91D with Al–Si powder

    Directory of Open Access Journals (Sweden)

    Ming Qian, Da Li and Chang Jin

    2008-01-01

    Full Text Available Blown-powder laser surface alloying was performed on the magnesium alloy AZ91D with Al–Si alloy powder to improve corrosion resistance. Characterization by scanning electron microscopy (SEM, energy dispersive spectroscopy (EDS and x-ray diffraction (XRD analysis revealed that intermetallic compounds (IMCs of Mg2Si, Al12Mg17 and Al3Mg2 were formed in the matrix of α-Mg and Al solid solutions in Al–Si alloyed layers. The anodic polarization test in 3.5% NaCl aqueous solution showed that preferential corrosion occurred in the α-Mg matrix of the AZ91D base metal. The Al–Si alloyed layers exhibited a lower corrosion rate and a higher polarization resistance than AZ91D. The compactly dispersed dendritic Mg2Si phase, and the dendritic and angular phases of Al12Mg17 and Al3Mg2 in the alloyed microstructure were observed to be corrosion-resistant, constituting a barrier that retards corrosion. Corrosion initiated at the interface between IMCs and the solid solution matrix, and at substructures of the matrix, subsequently pervaded into the surrounding microstructure.

  5. Temporal regulation of foregut development by HTZ-1/H2A.Z and PHA-4/FoxA.

    Directory of Open Access Journals (Sweden)

    Dustin L Updike

    2006-09-01

    Full Text Available The histone variant H2A.Z is evolutionarily conserved and plays an essential role in mice, Drosophila, and Tetrahymena. The essential function of H2A.Z is unknown, with some studies suggesting a role in transcriptional repression and others in activation. Here we show that Caenorhabditis elegans HTZ-1/H2A.Z and the remodeling complex MYS-1/ESA1-SSL-1/SWR1 synergize with the FoxA transcription factor PHA-4 to coordinate temporal gene expression during foregut development. We observe dramatic genetic interactions between pha-4 and htz-1, mys-1, and ssl-1. A survey of transcription factors reveals that this interaction is specific, and thus pha-4 is acutely sensitive to reductions in these three proteins. Using a nuclear spot assay to visualize HTZ-1 in living embryos as organogenesis proceeds, we show that HTZ-1 is recruited to foregut promoters at the time of transcriptional onset, and this recruitment requires PHA-4. Loss of htz-1 by RNAi is lethal and leads to delayed expression of a subset of foregut genes. Thus, the effects of PHA-4 on temporal regulation can be explained in part by recruitment of HTZ-1 to target promoters. We suggest PHA-4 and HTZ-1 coordinate temporal gene expression by modulating the chromatin environment.

  6. Corrosion behaviour of AZ91D and AM50 magnesium alloys with Nd and Gd additions in humid environments

    Energy Technology Data Exchange (ETDEWEB)

    Arrabal, R., E-mail: raularrabal@quim.ucm.es [Departamento de Ciencia de Materiales, Facultad de Ciencias Quimicas, Universidad Complutense, 28040 Madrid (Spain); Matykina, E.; Pardo, A.; Merino, M.C. [Departamento de Ciencia de Materiales, Facultad de Ciencias Quimicas, Universidad Complutense, 28040 Madrid (Spain); Paucar, K. [Gabinete de Corrosion, Facultad de Ingenieria Quimica y Textil, Universidad Nacional de Ingenieria, Cod. Postal 25, Lima (Peru); Mohedano, M.; Casajus, P. [Departamento de Ciencia de Materiales, Facultad de Ciencias Quimicas, Universidad Complutense, 28040 Madrid (Spain)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Mg alloys with additions of Nd and Gd were exposed to high humidity atmosphere. Black-Right-Pointing-Pointer The increase of Nd or Gd diminished the effect of micro-galvanic couples. Black-Right-Pointing-Pointer Corrosion resistance of the AM50 alloy improved with the addition of Nd or Gd by 43%. Black-Right-Pointing-Pointer Nd and Gd had no significant effect on the corrosion resistance of the AZ91D alloy. - Abstract: AM50 and AZ91D alloys modified with rare earths (RE) were evaluated under atmospheric conditions. Nd and Gd additions resulted in formation of Al{sub 2}RE and Al-Mn-RE compounds and reduction of the fraction of {beta}-phase. According to surface potential maps, RE-containing intermetallics were more noble than the {beta}-phase, but less than Al-Mn inclusions. As a result, the action of micro-galvanic couples depended on the added amount of RE and the initial alloy microstructure. Nd or Gd additions improved the corrosion resistance of the AM50 alloy by up to 43%, but had no significant effect on the corrosion resistance of the AZ91D alloy.

  7. Factores de competitividad de la agroindustria de la caña de azúcar en México

    Directory of Open Access Journals (Sweden)

    Noé Aguilar Rivera

    2011-01-01

    Full Text Available La industria azucarera de México integra actividades agrícolas de crecimiento, cosecha y transporte de caña a la producción de azúcar estándar y refinada, con otros productos y subproductos. Para competir en una economía global, es importante establecer criterios de desempeño para reducir costos de producción en términos de competitividad técnica, productividad y eficiencia en aspectos como rendimientos, caña de azúcar y agroindustrial por hectárea y de fábrica. En este artículo se discuten algunos indicadores de competitividad económica y técnica de la industria de caña de azúcar mexicana, con metodologías de benchmarking y diamante de Porter. Los resultados mostraron que son numerosos los factores técnicos y económicos que limitan el crecimiento, debido a que la industria mexicana se ha mantenido no competitiva y requiere mejorar e innovar en la reducción de costos, sobre todo en materia prima, cosecha y transporte. También está la diversificación, con base en los subproductos, como residuos de cosecha, bagazo, melazas, lodo de filtros y vinazas; esto es de gran importancia como fuente renovable de energía y materias primas.

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

    Science.gov (United States)

    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.

  9. Pea broth enhances the biocontrol efficacy of Lysobacter capsici AZ78 by triggering cell motility associated with biogenesis of type IV pilus

    Directory of Open Access Journals (Sweden)

    Selena Tomada

    2016-07-01

    Full Text Available 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 an d 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.

  10. Cambio en azúcares fermentables en la remolacha azucarera almacenada en atmósferas aerobia y anaerobia para la producción de etanol

    Directory of Open Access Journals (Sweden)

    Juan Manuel Vargas Ramírez

    2014-06-01

    Full Text Available Los métodos de almacenamiento de largo plazo son necesarios para preservar los azúcares fermentables en la remolacha y permitir el funcionamiento exitoso a lo largo del año en las plantas procesadoras para la obtención de etanol. Se estudió el almacenamiento anaeróbico de la remolacha azucarera como una alternativa al almacenamiento convencional en pilas a la intemperie utilizado actualmente en fábricas de azúcar de remolacha. Los resultados experimentales indican una pérdida de <15% en el total de los azúcares fermentables en la remolacha azucarera almacenada anaeróbicamente durante 14 semanas a 4 °C. Después de 14 semanas de almacenamiento, 99 ± 4% de los azúcares fermentables iniciales fueron preservados en la remolacha almacenada en condiciones aeróbicas a 4 °C. El almacenamiento aeróbico y anaeróbico de remolacha azucarera a 25 ° C conserva 82 ± 9 y 48 ± 11% del contenido de azúcar fermentable, respectivamente. Los azúcares fermentables y etanol en exudados contribuyeron insignificantemente (<3% para el rendimiento del etanol global de remolacha azucarera después del almacenamiento.

  11. The Lysobacter capsici AZ78 Genome Has a Gene Pool Enabling it to Interact Successfully with Phytopathogenic Microorganisms and Environmental Factors.

    Science.gov (United States)

    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.

  12. Preparation of Azidated Polybutadiene(Az-PBD)/Ethylene-Vinyl Acetate Copolymer(EVA) Blends for the Application of Energetic Thermoplastic Elastomer

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Sang Won; Choi, Myung Chan; Chang, Young-Wook; Noh, Si-Tae [Hanyang University, Ansan (Korea, Republic of); Kwon, Soon Kil [Agency for Defense Development, Daejeon (Korea, Republic of)

    2015-02-15

    A new energetic thermoplastic elastomer based on the azidated polybutadiene(Az-PBD)/ethylene vinyl acetate copolymer (EVA) blends was prepared, and structure and properties of the blends were investigated by SEM, DSC, DMA, tensile testing and combustion test. The Az-PBD was synthesized via a two-step process involving the addition reaction of commercially available 1,2-PBD with Br{sub 2} and subsequent nucleophilic substitution reaction of the brominated PBD with NaN{sub 3}. EVA/Az-PBD with 90/10, 80/20, 70/30 (wt/wt) was prepared by a solution blending. SEM, DSC, and DMA results revealed that the blends are partially compatible and Az-PBD is dispersed in continuous EVA matrix. Tensile test showed that modulus and tension set increased while elongation-at-break of the blends decreased with increasing Az-PBD content in the blends, but all the blends showed a elongation at break as high as 700% and a tension set of less than 5%, indicating that the blends are typically elastomeric. Combustion test showed that, with increasing Az-PBD content in the blend, higher energy can be released.

  13. Extended blood circulation and joint accumulation of a p(HPMA-co-AzMA)-based nanoconjugate in a murine model of rheumatoid arthritis.

    Science.gov (United States)

    Ebbesen, Morten F; Bienk, Konrad; Deleuran, Bent W; Howard, Kenneth A

    2014-01-01

    We recently synthesized a hydrophilic polymer, poly(N-(2-hydroxypropyl)methacrylamide-co-N-(3-azidopropyl)methacrylamide), p(HPMA-co-AzMA), by RAFT polymerization using a novel azide-containing methacrylamide monomer that through a post modification strategy using click chemistry enabled facile preparation of a panel of versatile and well-defined bioconjugates. In this work we screen a panel of different molecular weight (Mw) fluorescently tagged p(HPMA-co-AzMA) in healthy mice, by live bioimaging, to select an extended circulatory half-life material for investigating joint accumulation in a murine collagen antibody-induced arthritis model. Fluorescence image analysis revealed half-lifes of HPMA-co-AzMA) of 15, 36 and 54 kDa, respectively, with ~10% polymer retained in the blood after 24 h for the highest Mw. p(HPMA-co-AzMA) of 54 kDa showed enhanced accumulation in the joints of the arthritic mouse model with a bioavailability (AUC = 1783% · h) ~12 times higher (P = 0.01) than healthy control (AUC = 148% · h). p(HPMA-co-AzMA) of 54 kDa exhibited extended circulatory half-life and preferential accumulation in inflamed joints of a murine model of rheumatoid arthritis (RA). This combined with well-defined polymer size and versatility for conjugation of a range of biomolecules promotes p(HPMA-co-AzMA) for potential applications in the delivery of drugs for treatment of RA.

  14. Invesitgation of Drilling Parameters on Thrust Force on AZ91 Magnesium Alloy by Genetic Expression Programming

    Directory of Open Access Journals (Sweden)

    Kemal ALDAŞ

    2014-09-01

    Full Text Available Bu çalışmada AZ91 magnezyum alaşımının farklı parametreler altında işlenmesi ile oluşan kesme kuvvetlerinin deneysel tabanlı teorik bir model ile tahmin edilmesi sunulmuştur. Modelleme için gerekli deneyler kuru işleme ortamında ve işleme devri ilerleme hızı ve 4 farklı matkap ucunun tam faktöriyel deney tasarımı kullanarak gerçekleştirilmiştir. Deneyler sonucunca elde edilen veriler Genetic Expression yazılımı ile modellenerek kesme kuvveti tahmini için formulasyon oluşturulmuştur. Bu formulasyon kullanılarak deneyde kullanılan parametrelerin kesme kuvveti üzerindeki etkileri detaylı olarak analiz edilmiştir

  15. Evolution of rheocast microstructure of AZ31 alloy in semisolid state

    Directory of Open Access Journals (Sweden)

    Xing Bo

    2013-07-01

    Full Text Available Semisolid rheoforming (SSR is a promising technology for the production of Mg wrought alloy in foundry settings. In order to realize SSR, it is necessary to characterize the grain structure evolution during slurry preparation. In this paper, slurry of AZ31 alloy was produced by a novel rheocast process known as self-inoculation method (SIM. Interrupted quenching technology was applied to investigate the primary α-Mg evolution during continuous cooling and isothermal holding. Results indicate that the initial microstructure of slurry produced by SIM is a mixture of irregular grains, which becomes ideally globular when the slurry slowly cools to 620 ℃ and isothermally held for at least 30 s. The local solute diffusion leads to dendritic fragmentation and forms separated particles. During prolonged holding, the particle surface gradually becomes smooth because of protuberance melting and groove advancement. Coarsening of α-Mg grains in isothermal holding was analyzed using Lifshitz-Slyozov-Wagner theory. Results suggest that coalescence is most likely the dominant coarsening mechanism in the early stage while Ostwald ripening tends to be the principal one later. The EDS results indicate that a longer holding time leads to Al solute element segregation at the grain boundaries, but Zn distribution within liquid matrix has no obvious change.

  16. A Revisited Study of the Processing Map and Optimized Workability of AZ61 Magnesium Alloy

    Science.gov (United States)

    Zhou, X.; Liu, R. R.; Zhou, H. T.; Jiang, W. X.

    2017-05-01

    The hot deformation behavior of AZ61 magnesium alloy was studied by hot compression testing in the temperature range from 250 to 400 °C with strain rates from 10-3 to 1 s-1. Typical flow stress/true strain curves with the features of dynamic recrystallization (DRX) have been obtained. According to the flow stress curves, the processing maps were constructed via the dynamic material model (DMM). The maps exhibit a domain of DRX at temperatures between 330 and 370 °C and strain rates ranging from 10-3 to 10-2 s-1. The corresponding extrusion deformation was carried out in this DRX region. Gleeble 3500, optical microscopy (OM) and transmission electron microscopy (TEM) were used to characterize the microstructure evolution. The microstructure detection of this DRX region shows that the average grain size decreases with decreasing extrusion temperature. TEM observation further indicated that there are irregularly shaped subgrains with a high dislocation density, a dislocation network, the feature of dislocation pileup and an appearance of twin formation in the alloy hot-extruded using the parameters determined by our constructed processing maps.

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

    Science.gov (United States)

    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.

  18. Formation of Structure and Properties in Casting Processes on the Example of AZ91 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Augustyn B.

    2014-06-01

    Full Text Available Contemporary materials engineering requires the use of materials characterised by high mechanical properties, as these precisely properties determine the choice of material for parts of machinery and equipment. Owing to these properties it is possible to reduce the weight and, consequently, the consumption of both material and energy. Trying to meet these expectations, the designers are increasingly looking for solutions in the application of magnesium alloys as materials offering a very beneficial strength-to-weight ratio. However, besides alloying elements, the properties are to a great extent shaped by the solidification conditions and related structure. The process of structure formation depends on the choice of casting method forced by the specific properties of casting or by the specific intended use of final product. The article presents a comparison of AZ91 magnesium alloys processed by different casting technologies. A short characteristic was offered for materials processed by the traditional semi-continuous casting process, which uses the solidification rates comprised in a range of 5 - 20°C/s, and for materials made in the process of Rapid Solidification, where the solidification rate can reach 106 °C/s. As a result of the casting process, a feedstock in the form of billets and thin strips was obtained and was subjected next to the process of plastic forming. The article presents the results of structural analysis of the final product. The mechanical properties of the ø7 mm extruded rods were also evaluated and compared.

  19. EnviroAtlas - Phoenix, AZ - One Meter Resolution Urban Land Cover Data (2010)

    Science.gov (United States)

    The EnviroAtlas Phoenix, AZ land cover (LC) data and map were generated from USDA NAIP (National Agricultural Imagery Program) four band (red, green, blue and near-infrared) aerial photography taken from June through September, 2010 at 1 m spatial resolution. Seven land cover classes were mapped: water, impervious surfaces, soil and barren land, trees and forest, shrubs, grass and herbaceous non-woody vegetation, and agriculture. An accuracy assessment using a completely random sampling of 598 land cover reference points yielded an overall accuracy of 69.2%. The area mapped includes the entirety of the Central Arizona-Phoenix Long-Term Ecological Research (CAP-LTER) area, which was classified by the Environmental Remote Sensing and Geoinformatics Lab (ERSG) at Arizona State University. The land cover dataset also includes an area of approximately 625 square kilometers which is located north of Phoenix. This section was classified by the EPA land cover classification team. This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each at

  20. EnviroAtlas -Phoenix, AZ- One Meter Resolution Urban Land Cover Data (2010) Web Service

    Science.gov (United States)

    This EnviroAtlas web service supports research and online mapping activities related to EnviroAtlas (https://www.epa.gov/enviroatlas). The EnviroAtlas Phoenix, AZ land cover data and map were generated from USDA NAIP (National Agricultural Imagery Program) four band (red, green, blue and near-infrared) aerial photography taken from June through September, 2010 at 1 m spatial resolution. Seven land cover classes were mapped: water, impervious surfaces, soil and barren land, trees and forest, shrubland, grass and herbaceous non-woody vegetation, and agriculture. An accuracy assessment using a completely random sampling of 598 land cover reference points yielded an overall accuracy of 69.2%. The area mapped includes the entirety of the Central Arizona-Phoenix Long-Term Ecological Research (CAP-LTER) area, which was classified by the Environmental Remote Sensing and Geoinformatics Lab (ERSG) at Arizona State University. The land cover dataset also includes an area of approximately 625 square kilometers which is located north of Phoenix. This section was classified by the EPA land cover classification team. This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data

  1. Microstructure and tensile properties of thixo-diecast AZ91D magnesium alloy

    Directory of Open Access Journals (Sweden)

    Ai Xiulan

    2013-09-01

    Full Text Available The thixo-diecasting (TDC process is the combination of semi-solid billet preparation technology and die casting technology. The TDC process not only keeps the characteristics of thixo-forming but also has high efficiency and low cost. In the present work, the microstructures and mechanical properties of an AZ91D magnesium alloy prepared by the thixo-diecasting (TDC process were characterized in as-cast condition. The TDC alloy produced exhibits a unique microstructure containing α-Mg solid solution and β-Mg17Al12 intermetallic compound, and there are some small droplets and a small gray globule with eutectic structure in the primary α-Mg grains. The ultimate tensile strength and elongation of the TDC alloy also increase in comparison with other processes, such as thixocasting. Fracture surface observation shows that a crack mainly originates from the brittle fracture of the eutectic phases. The deformation of ductile α-Mg phase provides the TDC alloy with the main strain.

  2. Fibre Laser Cutting and Chemical Etching of AZ31 for Manufacturing Biodegradable Stents

    Directory of Open Access Journals (Sweden)

    Ali Gökhan Demir

    2013-01-01

    Full Text Available The use of magnesium-alloy stents shows promise as a less intrusive solution for the treatment of cardiovascular pathologies as a result of the high biocompatibility of the material and its intrinsic dissolution in body fluids. However, in addition to requiring innovative solutions in material choice and design, these stents also require a greater understanding of the manufacturing process to achieve the desired quality with improved productivity. The present study demonstrates the manufacturing steps for the realisation of biodegradable stents in AZ31 magnesium alloy. These steps include laser microcutting with a Q-switched fibre laser for the generation of the stent mesh and subsequent chemical etching for the cleaning of kerf and surface finish. Specifically, for the laser microcutting step, inert and reactive gas cutting conditions were compared. The effect of chemical etching on the reduction in material thickness, as well as on spatter removal, was also evaluated. Prototype stents were produced, and the material composition and surface quality were characterised. The potentialities of combining nanosecond laser microcutting and chemical etching are shown and discussed.

  3. Effect of solution treatment on microstructure and hardness of rheo-forming AZ91-Y alloy

    Directory of Open Access Journals (Sweden)

    Zhi-wei Wang

    2016-11-01

    Full Text Available The microstructure and hardness of rheo-forming AZ91-Y alloy before and after solution treatment (ST have been investigated by means of optical microscope (OM, scanning electron microscope (SEM equipped with energy dispersive spectroscopy (EDS, X-ray diffraction (XRD and Vickers. The experimental results showed that the β-Mg17Al12 phase of alloy was nearly dissolved after ST for 5 min. With the increasing of ST duration to 28 h, both the primary and secondarily solidified α-Mg grains faded away. At the same time, the alloy exhibited a much smoother surface due to the diffusion of solute atoms (Al. During ST, the thermal stable phase of Al2Y produced by ultrasonic vibration retained its size and morphology. As the ST duration was increased, the alloy hardness decreased sharply at first, and then gradually reached a minimum level. The alloy’s appropriate ST duration at 410 °C was approximately 28 h.

  4. A study of strontium doped calcium phosphate coatings on AZ31

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Satish S., E-mail: sss42@pitt.edu [Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Roy, Abhijit, E-mail: abr20@pitt.edu [Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Lee, Boeun E.; Ohodnicki, John; Loghmanian, Autrine [Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Banerjee, Ipsita [Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Kumta, Prashant N., E-mail: pkumta@pitt.edu [Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Center for Craniofacial Regeneration, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Department of Mechanical Engineering and Materials Science, University of Pittsburgh, PA 15261 (United States)

    2014-07-01

    Calcium phosphate (CaP) coatings have been studied to tailor the uncontrolled non-uniform corrosion of Mg based alloys while simultaneously enhancing bioactivity. The use of immersion techniques to deposit CaP coatings is attractive due to the ability of the approach to coat complex structures. In the current study, AZ31 substrates were subjected to various pretreatment conditions prior to depositing Sr{sup 2+} doped and undoped CaP coatings. It was hypothesized that the bioactivity and corrosion protection of CaP coatings could be improved by doping with Sr{sup 2+}. Heat treatment to elevated temperatures resulted in the diffusion of alloying elements, Mg and Zn, into the pretreated layer. Sr{sup 2+} doped and undoped CaP coatings formed on the pretreated substrates consisted of biphasic mixtures of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA). Electrochemical corrosion experiments indicated that the extent of Sr{sup 2+} doping and pretreatment both influenced the corrosion protection. Cytotoxicity was evaluated with MC3T3-E1 mouse preosteoblasts and human mesenchymal stem cells (hMSCs). For both cell types, proliferation decreased upon increasing the Sr{sup 2+} concentration. However, both osteogenic gene and protein expression significantly increased upon increasing Sr{sup 2+} concentration. These results suggest that Sr{sup 2+} doped coatings are capable of promoting osteogenic differentiation on degradable Mg alloys, while also enhancing corrosion protection, in comparison to undoped CaP coatings.

  5. The Effects of Carbon Nanotubes on the Mechanical and Wear Properties of AZ31 Alloy

    Directory of Open Access Journals (Sweden)

    Mingyang Zhou

    2017-12-01

    Full Text Available Carbon nanotube (CNT-reinforced AZ31 matrix nanocomposites were successfully fabricated using a powder metallurgy method followed by hot extrusion. The influence of CNTs on microstructures, mechanical properties, and wear properties were systematically investigated by optical microscope (OM, scanning electron microscope (SEM, X-ray diffraction (XRD, hardness test, tensile test, and wear test. The results revealed that the nanocomposites showed a slightly smaller grain size compared with the matrix and uniform distribution that CNTs could achieve at proper content. As a result, the addition of CNTs could weaken basal plane texture. However, the yield strength and ultimate tensile strength of the composites were enhanced as the amount of CNTs increased up to 2.0 wt. %, reaching maximum values of 241 MPa (+28.2% and 297 MPa (+6.1%, respectively. The load transfer mechanism, Orowan mechanism, and thermal mismatch mechanism played important roles in the enhancement of the yield strength, and several classical models were employed to predict the theoretical values. The effect of CNT content on the friction coefficient and weight loss of the nanocomposites was also studied. The relationships between the amount of CNTs, the friction coefficient, and weight loss could be described by the exponential decay model and the Boltzmann model, respectively.

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

    Science.gov (United States)

    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.

  7. LSP/MAO composite bio-coating on AZ80 magnesium alloy for biomedical application.

    Science.gov (United States)

    Xiong, Ying; Hu, Qiang; Song, Renguo; Hu, Xiaxia

    2017-06-01

    A composite bio-coating was fabricated on AZ80 magnesium (Mg) alloy by using micro-arc oxidation (MAO) under the pretreatment of laser shock peening (LSP) in order to improve the bio-corrosion resistance and the mechanical integrity. LSP treatment could induce grain refinement and compressive residual stress field on the surface of material. MAO bio-coating was grown in alkaline electrolyte with hydroxyapatite (HA, Ca10(PO4)6(OH)2) to improve the biological properties of the material. The microstructure, element and phase composition for untreated based material (BM) and treated samples (LSP layer, MAO bio-coating and LSP/MAO composite bio-coating) were investigated by transmission electron microscopy (TEM), scanning electron microscope (SEM), energy dispersion spectroscopy (EDS) and X-ray diffraction (XRD). Electrochemical tests and slow strain rate tensile (SSRT) tests were used to evaluate the corrosion resistance and the stress corrosion susceptibility in simulated body fluid (SBF). The results indicated that LSP/MAO composite bio-coating can not only improve the corrosion resistance of Mg alloy substrate evidently but also increase the mechanical properties in SBF compared to LSP layer and MAO bio-coating. Mg alloy treated by LSP/MAO composite technique should be better suited as biodegradable orthopedic implants. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents.

    Science.gov (United States)

    Zhang, Yaowu; Kent, Damon; Wang, Gui; StJohn, David; Dargusch, Matthew S

    2014-11-01

    Mg alloys are receiving considerable attention for biomedical stents due to their combination of good mechanical properties and high biodegradability. Cold rolling is necessary to process Mg alloy tubes before final drawing and fabrication of the magnesium stents. In this paper, cold-rolled tubes were subjected to a cross-sectional reduction rate (ε) of up to 19.7%, and were further processed at various ratios of wall-thickness to diameter reduction (Q) from 0 to 2.24 with a constant ε of 19.7%. The results show that the cold-rolled tubes exhibited a rise in ultimate tensile strength (UTS), yield strength (YS), and a reduction in elongation as ε increased from 5.5% to 19.7%. UTS, YS and elongation decreased when Q was increased from 0 to 2.24. Mechanical twinning was observed and analysed. Extension twins increased with increasing ε and were almost saturated at a ε of 16.5%. Extension twins play an important role in determining the evolution of mechanical behaviour in the case of increasing ε, whilst contraction/double twins and secondary extension twins have a large effect on mechanical behaviour in the case of varying Q. The results indicate that the proportions and types of twins play a major role in determining the mechanical behaviour of the AZ31 tubes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. On numerical modeling of low-head direct chill ingot caster for magnesium alloy AZ31

    Directory of Open Access Journals (Sweden)

    Mainul Hasan

    2014-12-01

    Full Text Available A comprehensive 3D turbulent CFD study has been carried out to simulate a Low-Head (LH vertical Direct Chill (DC rolling ingot caster for the common magnesium alloy AZ31. The model used in this study takes into account the coupled laminar/turbulent melt flow and solidification aspects of the process and is based on the control-volume finite-difference approach. Following the aluminum/magnesium DC casting industrial practices, the LH mold is taken as 30 mm with a hot top of 60 mm. The previously verified in-house code has been modified to model the present casting process. Important quantitative results are obtained for four casting speeds, for three inlet melt pouring temperatures (superheats and for three metal-mold contact heat transfer coefficients for the steady state operational phase of the caster. The variable cooling water temperatures reported by the industry are considered for the primary and secondary cooling zones during the simulations. Specifically, the temperature and velocity fields, sump depth and sump profiles, mushy region thickness, solid shell thickness at the exit of the mold and axial temperature profiles at the center and at three strategic locations at the surface of the slab are presented and discussed.

  10. Semi-continuous casting of magnesium alloy AZ91 using a filtered melt delivery system

    Directory of Open Access Journals (Sweden)

    Mainul Hasan

    2015-12-01

    Full Text Available A 3-D numerical simulation of an industrial-sized slab caster for magnesium alloy AZ91 has been carried out for the steady state operational phase of the caster. The simulated model consists of an open-top melt delivery system fitted with a porous filter near the hot-top. The melt flow through the porous filter was modeled on the basis of Brinkmann-Forchimier-Extended non-Darcy model for turbulent flow. An in-house 3-D CFD code was modified to account for the melt flow through the porous filter. Results are obtained for four casting speeds namely, 40, 60, 80, and 100 mm/min. The metal-mold contact region as well as the convective heat transfer coefficient at the mold wall were also varied. In addition to the above, the Darcy number for the porous media was also changed. All parametric studies were performed for a fixed inlet melt superheat of 64 °C. The results are presented pictorially in the form of temperature and velocity fields. The sump depth, mushy region thickness, solid shell thickness at the exit of the mold and axial temperature profiles are also presented and correlated with the casting speed through regression analysis.

  11. Mono-carboxylate conversion coatings for AZ31 Mg alloy protection

    Energy Technology Data Exchange (ETDEWEB)

    Frignani, A.; Grassi, V.; Zucchi, F.; Zanotto, F. [Corrosion Study Centre A. Dacco, University of Ferrara (Italy)

    2011-11-15

    Conversion coatings on a magnesium alloy were obtained by dipping AZ31 specimens in aqueous solutions of sodium salts of mono-carboxylic acids (stearic, palmitic, myristic, lauric, mono-carboxylate ion concentration from 1 to 5 mM, depending on the salt solubility) for 24 and 72 h at room temperature, or 24 h at 50 C. The influence exerted by the treatment time, bath temperature and alkyl chain length on the efficiency of these coatings was studied. The performances of the coatings were evaluated by potentiodynamic polarization curve recording after 1 h immersion in 0.05 M Na{sub 2}SO{sub 4} solution, while their temporal evolution was monitored by electrochemical impedance spectroscopy (EIS) spectra during 24 h. Further and long lasting tests were carried out also in 0.1 M NaCl solution. The efficiency of the coatings depended on the aliphatic chain length, and increased as the treatment time and the bath temperature were increased. The coating of lower homologue only hindered the cathodic process, while those of the higher homologues markedly inhibited the anodic process too. The best performances were displayed by 24 h-50 C stearic conversion coating, which maintained a very high efficiency for over 800 h immersion in 0.05 M sulphate solution. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. New Az/El mount for Haystack Observatory's Small Radio Telescope kit

    Science.gov (United States)

    Cobb, M. L.

    2005-12-01

    The Small Radio Telescope (SRT) kit was designed by Haystack Observatory as part of their educational outreach effort. The SRT uses a custom designed FFT based radio spectrometer receiver with a controller to position a 2.3m dish to make various radio astronomy observations including the 21 cm spin flip line of atomic hydrogen. Because there is no sizable commercial market for a two dimensional mount for dishes of this size, finding an appropriate provider as been a recurring problem for the project. Originally, the kit used a modified motor mount from Kaultronics called the H180. Two of these motors were combined by a specially designed adaptor to allow motion in azimuth and elevation. When Kaultronics was bought out by California Amplifier they discontinued production of the H180. The next iteration used a compact unit called the alfa-spid which was made in Germany and imported through Canada. The alfa-spid was designed to point various ham radio antennas and proved problematic with 2.3m dishes. Most recently the CASSI (Custom Astronomical Support Services, Inc.) corporation has designed and certified a robust Az/El mount capable of supporting dishes up to 12 feet (3.6m) with 100 MPH wind loads. This paper presents the design and operating characteristics of the new CASSI mount. The CASSI mount is now shipped with the SRT kit and should serve the project well for the foreseeable future.

  13. Texture-based formability prediction for Mg wrought alloys ZE10 and AZ31

    Science.gov (United States)

    Steglich, D.; Jeong, Y.

    2017-10-01

    A viscoplastic self-consistent crystal plasticity model was employed to study the formability of two magnesium sheet alloys, i.e., AZ31 and ZE10 at 200 °C. The flow stress-strain curves obtained by uniaxial tension tests at various strain rates and the crystallographic texture were used to determine the model parameters. The crystal plasticity model was incorporated with the Marciniak-Kuczyński model in order to address the forming limits of the magnesium sheets. Model predictions were matched with the experimental data obtained by Nakajima tests by tuning the respective parameters. The model was further applied to quantify the effect of the initial crystallographic texture on the formability. Virtual textures representing realistic outcome from mechanical working (rolling, extrusion) were generated. The respective effects on the formability were quantified. The resulting forming limit diagrams demonstrate that the variations of crystallographic texture can either lead to an improvement or to a detrimental reduction of the forming strain in particular in stretch-forming operations.

  14. Study of twinning behaviors of rolled AZ31 magnesium alloy by interrupted in situ compressive tests

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Dewen [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Liu, Tianmo, E-mail: tmliu@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Shi, Dongfeng; Chen, Huicong [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Chen, Hongbing [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); College of Engineering and Technology, Southwest University, Chongqing 400716 (China)

    2016-01-20

    In this paper rolled AZ31 magnesium alloy was deformed by interrupted in situ compressive tests. Compressive and re-compressive tests were conducted along rolling direction (RD). It is discovered that the yield strength of re-compression is enhanced due to grain refinement by {10–12} tensile twins. Twinning activation and evolution are evidenced by electron backscatter diffraction. Correlations with grain orientation and boundary misorientation are observed in the region of twins that arise at grain boundaries. The distributions of grain boundary misorientation associated with twin nucleation are mapped. It is found that nucleation of twin is mainly controlled by the initial texture, and is more easy at low misorientation grain boundaries. The growth of twins depend on two modes: the thickening of the existing twin lamellae and new twins is nucleated at grain boundary. With increasing compressive strain, the growth and coalescence of twins eventually encompassed the whole grain. Meanwhile, the basal texture is weaker after compression due to the propagation and coalescence of tensile twins.

  15. Failure behavior of high pressure die casting AZ91D magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.; Xiong, S.M. [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Tsinghua University, Beijing 100084 (China); Guo, Z., E-mail: zhipeng_guo@mail.tsinghua.edu.cn [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Tsinghua University, Beijing 100084 (China)

    2016-08-30

    The failure behavior of high pressure die casting AZ91D magnesium alloy during both tensile and fatigue tests was studied in situ by using scanning electron microscope. Attention was focused on the role of microstructure played in crack initiation and propagation. Results showed that the defects in castings, including gas pore, shrinkage pore and defect band, were the crack initiation sources. In tensile test, the crack propagated in a combination of intergranular and transgranular modes, and the specimen fractured by connecting defects at the section with minimum effective force bearing area. In fatigue test, the crack propagated in a transgranular mode at specific crystalline planes. When the crack was in contact with the β-phase, the crack would pass through, and fracture the network β-phase, whereas bypass the island β-phase by detaching it from the surrounding α-Mg grains. Besides, defects in front of the crack would act as the secondary crack initiation sources, from which new cracks would initiate and propagate. With the propagation of the fatigue crack, the actual maximum cyclic stress would increase to the fracture stress of the left cross section and lead to the final fracture of the specimen.

  16. Wettability and corrosion of alumina embedded nanocomposite MAO coating on nanocrystalline AZ31B magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gheytani, M.; Aliofkhazraei, M., E-mail: maliofkh@gmail.com; Bagheri, H.R.; Masiha, H.R.; Rouhaghdam, A. Sabour

    2015-11-15

    In this paper, micro- and nanocrystalline AZ31B magnesium alloy were coated by micro-arc oxidation method. In order to fabricate nanocrystalline surface layer, surface mechanical attrition treatment was performed and nano-grains with average size of 5–10 nm were formed on the surface of the samples. Coating process was carried out at different conditions including two coating times and two types of electrolyte. Alumina nanoparticles were utilized as suspension in electrolyte to form nanocomposite coatings by micro-arc oxidation method. Potentiodynamic polarization, percentage of porosity, and wettability tests were performed to study various characteristics of the coated samples. The results of scanning electron microscope imply that samples coated in silicate-based electrolyte involve much lower surface porosity (∼25%). Besides, the results of wettability test indicated that the maximum surface tension with deionized water is for nanocrystalline sample. In this regard, the sample coated in silicate-based suspension was 4 times more hydrophilic than the microcrystalline sample. - Highlights: • MAO in phosphate electrolyte needs higher energy as compared to silicate electrolyte. • Less porosity and finer grain size on free surface of the silicate-based coatings. • Observed porosity from top surface of coating shows the effect of the final MAO sparks. • SMAT affects surface roughness and accelerates growth kinetics.

  17. Variant selection of primary extension twins in AZ31 magnesium deformed at 400 °C

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X., E-mail: liuxiao0105@163.com [College of Mechanical and Electrical Engineering, Hunan University of Science and Technology, Xiangtan, Hunan 411201 (China); State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan 410082 (China); Jonas, J.J. [Department of Materials Engineering, McGill University, 3610 University St., Montreal, QC, Canada H3A 2B2 (Canada); Zhu, B.W. [College of Mechanical and Electrical Engineering, Hunan University of Science and Technology, Xiangtan, Hunan 411201 (China); Wang, T. [Department of Materials Engineering, McGill University, 3610 University St., Montreal, QC, Canada H3A 2B2 (Canada); Li, L.X. [State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan 410082 (China)

    2016-01-01

    Uniaxial compression tests were performed at 400 °C and a strain rate of 0.3 s{sup −1} on samples of as-extruded AZ31 magnesium alloy. At a true strain of −0.1, many extension twins were detected. The orientations of selected twins and their host matrix grains were determined by electron backscattered diffraction (EBSD) techniques. The Schmid factors (SFs) and accommodation strains associated with both the observed and absent potential twins were calculated. Analysis of the data indicated that some of the selected twins obeyed a Schmid factor criterion and others did not. In the latter cases, it was the accommodation strain that controlled the formation of the non-Schmid twins. Potential high SF twins did not form if this would have required the operation of ‘difficult’ deformation modes (i.e. prismatic or pyramidal slip and twinning). Their place was taken by low SF twins whose formation required little accommodation work. Thus it appears that the variant selection criteria originally derived for ambient temperature straining continue to apply at 400 °C, despite the much lower values of the CRSS’s of the difficult deformation modes.

  18. Dynamic tensile behavior of AZ31B magnesium alloy at ultra-high strain rates

    Directory of Open Access Journals (Sweden)

    Geng Changjian

    2015-04-01

    Full Text Available The samples having {0001} parallel to extruding direction (ED present a typical true stress–true strain curve with concave-down shape under tension at low strain rate. Ultra-rapid tensile tests were conducted at room temperature on a textured AZ31B magnesium alloy. The dynamic tensile behavior was investigated. The results show that at ultra-high strain rates of 1.93 × 102 s−1 and 1.70 × 103 s−1, the alloy behaves with a linear stress–strain response in most strain range and exhibits a brittle fracture. In this case, {10-12}  extension twinning is basic deformation mode. The brittleness is due to the macroscopic viscosity at ultra-high strain rate, for which the external critical shear stress rapidly gets high to result in a cleavage fracture before large amounts of dislocations are activated. Because {10-12} tension twinning, {10-11} compressive twinning, basal slip, prismatic slip and pyramidal slip have different critical shear stresses (CRSS, their contributions to the degree of deformation are very differential. In addition, Schmid factor plays an important role in the activity of various deformation modes and it is the key factor for the samples with different strain rates exhibit various mechanical behavior under dynamic tensile loading.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mackie, D.; Robson, J.D.; Withers, P.J. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Turski, M. [Magnesium Elektron UK, Rake Lane, Manchester, M27 8BF (United Kingdom)

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

    Science.gov (United States)

    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.

  1. Periodismo latinoamericano: preocupaciones y desafíos (Entrevista a Eleazer Díaz Rangel

    Directory of Open Access Journals (Sweden)

    Pablo Portales

    2015-01-01

    Full Text Available Eleazer Díaz Rangel, ha habido pocos cambios en los últimos años en relación a los problemas de la libertad de información y libertad de opinión. En los regímenes autoritarios subsisten severas limitaciones a estas libertades y, en consecuencia, al ejercicio de la profesión periodística. En otros países, se ha mantenido una situación que permite un ejercicio sin mayores limitaciones. Sin embargo, hay hechos destacables como la ininterrumpida "apertura política brasileña" y la "consolidación democrática" en Ecuador. Pero, por otra parte, Guatemala y El Salvador se han convertido en los lugares más peligrosos del mundo para ejercer el periodismo. En los últimos 18 meses 40 periodistas han muerto o fueron secuestrados. La situación socio-económica de los periodistas, mientras en algunos países se producen mejoramientos graduales, en otros se advierte un estancamiento. Ahora, un factor nuevo que aparece en las preocupaciones profesionales es la incorporación de nuevas tecnologías: la implantación de sistemas de video en algunos grandes diarios de América Latina está introduciendo cambios en el ejercicio de la profesión.

  2. Effect of Forging on Microstructure, Texture, and Uniaxial Properties of Cast AZ31B Alloy

    Science.gov (United States)

    Toscano, D.; Shaha, S. K.; Behravesh, B.; Jahed, H.; Williams, B.

    2017-07-01

    The effect of open-die hot forging on cast AZ31B magnesium alloy was investigated in terms of the evolution of microstructure, texture, and mechanical properties. A refined microstructure with strong basal texture was developed in forged material. A significant increase in tensile yield and ultimate strengths by 143 and 23%, respectively, was determined as well. When tested in compression at room temperature, the forged alloy displayed significant in-plane asymmetry and unchanged yield strength compared to the cast alloy owing to the activation of 10\\bar{1}2} cast and forged conditions. However, the ultimate compressive strength for the forged material increased by 22 percent compared to the as-cast material. Microstructure and texture analysis of the fracture samples confirmed that the deformation of the forged samples was dominated by slip during tension and twin in compression. In comparison, both slip and twin were observed in the cast samples for similar testing conditions. The increase in strength of forging was attributed to the refinement of grains and the formation of strong basal texture, which activated the non-basal slip on the prismatic and pyramidal slip systems instead of extension twin.

  3. Effect of Graphite Powder Amount on Surface Films Formed on Molten AZ91D Alloy

    Science.gov (United States)

    Li, Weihong; Zhou, Jixue; Ma, Baichang; Wang, Jinwei; Wu, Jianhua; Yang, Yuansheng

    2017-10-01

    Graphite powder was adopted to prevent AZ91D magnesium alloy from oxidizing during the melting and casting process. The microstructure of the resultant surface films formed on the molten alloy protected by 0, 2.7, 5.4, 8.1, and 10.8 g dm-2 graphite powder at 973 K (700 °C) for holding time of 30 minutes was investigated by scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction, and the thermodynamic method. The results indicated that the surface films were composed of a protective layer and the underneath MgF2 particles with different morphology. The protective layer was continuous with a thickness range from 200 to 550 nm consisting of magnesium, oxygen, fluorine, carbon, and a small amount of aluminium, possibly existing in the form of MgO, MgF2, C, and MgAl2O4. The surface films were the result of the interaction between the graphite powder, the melt, and the ambient atmosphere. The unevenness of the micro surface morphology and the number and size of the underneath MgF2 particles increased with graphite powder amount. The mechanism of the effect of graphite powder amount on the resultant surface films was also discussed.

  4. Resistance-Spot-Welded AZ31 Magnesium Alloys: Part I. Dependence of Fusion Zone Microstructures on Second-Phase Particles

    Science.gov (United States)

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

    2010-03-01

    A comparison of microstructural features in resistance spot welds of two AZ31 magnesium (Mg) alloys, AZ31-SA (from supplier A) and AZ31-SB (from supplier B), with the same sheet thickness and welding conditions, was performed via optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). These alloys have similar chemical composition but different sizes of second-phase particles due to manufacturing process differences. Both columnar and equiaxed dendritic structures were observed in the weld fusion zones of these AZ31 SA and SB alloys. However, columnar dendritic grains were well developed and the width of the columnar dendritic zone (CDZ) was much larger in the SB alloy. In contrast, columnar grains were restricted within narrow strip regions, and equiaxed grains were promoted in the SA alloy. Microstructural examination showed that the as-received Mg alloys contained two sizes of Al8Mn5 second-phase particles. Submicron Al8Mn5 particles of 0.09 to 0.4 μm in length occured in both SA and SB alloys; however, larger Al8Mn5 particles of 4 to 10 μm in length were observed only in the SA alloy. The welding process did not have a great effect on the populations of Al8Mn5 particles in these AZ31 welds. The earlier columnar-equiaxed transition (CET) is believed to be related to the pre-existence of the coarse Al8Mn5 intermetallic phases in the SA alloy as an inoculant of α-Mg heterogeneous nucleation. This was revealed by the presence of Al8Mn5 particles at the origin of some equiaxed dendrites. Finally, the columnar grains of the SB alloy, which did not contain coarse second-phase particles, were efficiently restrained and equiaxed grains were found to be promoted by adding 10 μm-long Mn particles into the fusion zone during resistance spot welding (RSW).

  5. Investigation of the chemical vicinity of defects in Mg and AZ31 with positron coincident Doppler boarding spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stadlbauer, Martin

    2008-03-10

    Within the scope of the present work, two main goals have been achieved: Firstly, the coincident Doppler broadening spectrometer (CDBS) at the high intense positron source NEPOMUC has been elaborately improved in order to increase the spatial resolution for defect mapping measurements and to investigate samples with shallow positron trapping sites which are present e. g. in magnesium. Secondly, as an application, the chemical vicinity of defects in the industrially used magnesium based alloy AZ31 has been examined by means of the detailed investigation of ion-irradiated specimen with positron annihilation spectroscopy. Detailed simulations with the finite-element simulation tool COMSOL were used to optimize the focal diameter of the positron beam at the sample position in order to increase the spatial resolution. With a value of 0.3 mm, sub-mm resolution has now been reached. The CDBS has been furthermore equipped with a sample cooling unit in order to reach liquid nitrogen temperature, maintaining the feature of scanning the sample for defect mapping. Defects and their chemical surrounding in ion irradiated magnesium and the magnesium based alloy AZ31 were then investigated on an atomic scale with the CDBS. In the respective spectra the chemical information and the defect contribution have been thoroughly separated. For this purpose, samples of annealed Mg were irradiated with Mg-ions in order to create exclusively defects. In addition Al- and Zn-ion irradiations on Mg-samples were performed in order to create samples with both defects and impurity atoms. The ion irradiated area on the samples was investigated with laterally and depth resolved positron Doppler broadening spectroscopy (DBS) and compared with SRIM-simulations of the vacancy distribution. The investigation of the chemical vicinity of crystal defects in AZ31 was performed with CDBS on Mg-ion irradiated AZ31 with Mg-ion irradiated Mg. The outer tail of the energy distribution in the annihilation

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

    Science.gov (United States)

    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

  7. [11C]AZ10419096 - a full antagonist PET radioligand for imaging brain 5-HT1B receptors.

    Science.gov (United States)

    Lindberg, Anton; Nag, Sangram; Schou, Magnus; Takano, Akihiro; Matsumoto, Junya; Amini, Nahid; Elmore, Charles S; Farde, Lars; Pike, Victor W; Halldin, Christer

    2017-11-01

    The serotonergic system is widely present in all regions of the central nervous system (CNS) and plays a key modulatory role in many of its functions. Positron emission tomography (PET) is used to study several serotonin receptors in CNS in vivo. The G-protein coupled receptor 5-HT1B is mostly present in the occipital cortex and in midbrain and is linked to several psychiatric disorders. There is evidence that agonist PET radioligands for neuroreceptors are more sensitive to endogenous neurotransmitters than antagonists. Our previously developed 5-HT1B receptor PET radioligand, [11C]AZ10419369, is now considered a partial agonist. In this work we are aiming to develop a full antagonist PET radioligand for imaging brain 5-HT1B receptors, and evaluate its sensitivity to increased endogenous serotonin concentration. [11C]AZ10419096 was synthesized by rapid methylation of the prepared corresponding N-desmethyl precursor with [11C]methyl triflate. Five PET measurements were performed in cynomolgus monkeys, consisting of two at baseline, one after treatment of a monkey with a 5-HT1B antagonist, AR-A000002, and two in which fenfluramine was administered during scanning to induce endogenous serotonin release. [11C]AZ10419096 was synthesized in high yield and purity within 30 min, including purification, formulation and sterile filtration. The baseline PET measurements demonstrated [11C]AZ10419096 to have favorable radioligand characteristics, including high specific binding in brain regions that have high 5-HT1B density, such as occipital cortex and globus pallidus, as well as subsequent rapid elimination from brain and a minor abundance of lipophilic radiometabolites in plasma. AR-A00002 completely blocked radioligand receptor-specific binding. Fenfluramine produced a distinct displacement of radioligand consistent with an expected increase of synaptic endogenous serotonin concentration. [11C]AZ10419096, a full 5-HT1B antagonist PET radioligand, demonstrates high specific

  8. Development of mechanical properties in a CaO added AZ31 magnesium alloy processed by equal-channel angular pressing

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Seong-Hwan [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Metal Forming Technology R& D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Jung, Ki Ho; Shin, Young-Chul; Yoon, Duk Jae [Metal Forming Technology R& D Group, Korea Institute of Industrial Technology, Incheon 406-840 (Korea, Republic of); Kawasaki, Megumi, E-mail: megumi@hanyang.ac.kr [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States)

    2016-02-15

    Processing through the application of equal-channel angular pressing (ECAP) is recognized as one of the attractive severe plastic deformation techniques where the processed bulk metals generally achieve ultrafine-grained microstructure leading to improved physical characteristics and mechanical properties. Magnesium has received much attention to date for its lightweight, high strength and excellent elasticity. Mg alloys with addition of CaO is reported to provide the successful casting procedure without usage of greenhouse gas, SF{sub 6}, whereas it is generally used for preventing the oxidation of Mg during casting. In the present investigation, a CaO added AZ31 (AZ31-CaO) magnesium alloy was processed by ECAP at elevated temepratures with a few steps of reduction which result in significant grain refinement to ~ 1.5 μm after 6 passes. Compression testing at room temperature demonstrated the AZ31-CaO alloy after ECAP showed enhanced yield strength more than the as-processed commercial AZ31 alloy while both alloys maintained ductility in spite of significant reduction in grain size. The improved strength in the AZ31-CaO alloy was attributed to the formation of fine Al{sub 2}Ca precipitates which experience breaking-up through ECAP and accelerate the microstructural refinement. Moreover, the preservation of ductility was attributed to the enhancement of strain hardening capability in the AZ31 alloy at room temperature. This study discusses the feasibility of using ECAP to improve both strength and ductility on magnesium alloys by applying the diagram describing the paradox of strength and ductility. - Highlights: • AZ31 and AZ31-CaO magnesium alloys were processed by ECAP up to 6 passes. • AZ31-CaO alloy after ECAP showed improved yield strength without losing ductility. • CaO in AZ31 forms fine Al{sub 2}Ca accelerating microstructural refinement during ECAP. • Feasibility of using ECAP was shown to improve both strength and ductility in Mg.

  9. Vida de Carmen Caamaño Díaz : una voz del exilio interior

    Directory of Open Access Journals (Sweden)

    Mercedes Montero Caldera

    1999-01-01

    Full Text Available Este artículo recoge el testimonio oral de Carmen Caamaño Díaz (Madrid, 1911, quien a través de su memoria hace un recorrido autobiográfico en el que manifiesta la evolución de un compromiso ideológico que la convertiría en sujeto activo del exilio interior durante el régimen franquista. En su etapa universitaria, Carmen fue miembro de la junta Directiva de la FUE (Federación Española de Enseñantes y Secretaria General de la UFEH (Unión Federal de estudiantes Hispanoamericanos desde 1930 a 1931. Licenciada en Filosofía y Letras, trabajó en él Centro de estudios tiistohcos formando parte del equipo de investigación que dirigía Claudio Sáncfiez Albornoz. En 1937 ingresó en el P.C.E, desempeñando, entre otros cargos, el de Gobernadora Civil de Cuenca desde enero a marzo de 1939. Al finalizar la guerra, fue detenida y condenada a prisión. En 1941 trató de reorganizar en la clandestinidad el partido comunista en la provincia de Alicante, siendo nuevamente detenida y condenada a muerte, pena que le sería conmutada por la de cárcel. Depurada profesionalmente y bajo control policial durante varios años, su actividad de oposición al régimen de Franco la llevaría a cabo desde la Asociación de Mujeres Universitarias.This article includes the oral statement of Carmen Caamaño Díaz (Madrid, 1911, who covers her autobiography through her memory, expressing an ideogical compromise evolution through which she would become an active subjet of the inner exile throughout Franco's regime. While being a student at university, she was a member of the Board of Directors of the UFEH (Spanish Teachers Union and General Secretary of the UFEH (Latin American Student Union from 1930 to 1931. With a degree in Arts, she worked at the Centre of Historie Studies taking part within the investigation team conducted by Claudio Sánchez Albornoz. In 1937 she joined the Spanish Communist Party, performing the charge, amongst others, of Civil Governor

  10. Interfacial microstructure and mechanical properties of Cf/AZ91D composites with TiO2and PyC fiber coatings.

    Science.gov (United States)

    Li, Shaolin; Qi, Lehua; Zhang, Ting; Ju, Luyan; Li, Hejun

    2017-10-01

    In spite of the effectiveness of the fiber coatings on interface modification of carbon fiber reinforced magnesium matrix composites, the cost and exclusive equipment for the coatings preparation are usually ignored during research work. In this paper, pyrolytic carbon (PyC) and TiO 2 were coated on carbon fiber surface to study the effects of fiber coatings on interfacial microstructure and mechanical properties of carbon fiber reinforced AZ91D composites (C f /AZ91D composites). It was indicated that both the two coatings could modify the interface and improve the mechanical properties of the composites. The ultimate tensile strength of the TiO 2 -C f /AZ91D and the PyC-C f /AZ91D composite were 333MPa and 400MPa, which were improved by 41.7% and 70.2% respectively, compared with the untreated-C f /AZ91D composite. The microstructure observation revealed that the strengthening of the composites relied on fiber integrity and moderate interfacial bonding. MgO nano-particles were generated at the interface due to the reaction of TiO 2 with Mg in the TiO 2 -C f /AZ91D composite. The volume expansion resulting from the reaction let to disordered intergranular films and crystal defects at the interface. The fibers were protected and the interfacial reaction was restrained by PyC coating in the PyC-C f /AZ91D composite. The principle to select the coating of fiber was proposed by comparing the effectiveness and cost of the coatings. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Plasma electrolytic oxidation of AZ91D magnesium alloy with different additives and its corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Fa-he; Cao, Jiang-lin; Zhang, Zhao [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Zhang, Jian-qing; Cao, Chu-nan [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); State Key Laboratory for Corrosion and Protection, Institute of Metal Research, The Chinese Academy of Sciences, Shenyang 110016 (China)

    2007-09-15

    Plasma electrolytic oxidation (PEO) of Mg-based AZ91D alloys was investigated using 50 Hz AC anodizing technique in an alkaline borate solution, which contained a new kind of organic additive and without F, P, and Cr. The anodizing technological parameters have been optimized and a kind of ivory-white smooth anodic film with high corrosion resistance was obtained. It was found that the formation of the anodic films was always coupled with sparking and oxygen evolution, whose intensity changed with the additive and anodizing voltage. All EIS plots have two capacitive loops and one low frequency inductive component. Two capacitive arcs present the barrier and porous layer of the PEO film and the inductive component in the low frequency domain is a complex behavior due to the porous structure connected to the electrolyte. EIS plots and fitting results show that a self-sealing process of the PEO firm with different additives takes place in the beginning of immersion time, then corrosion attack becomes a preponderant process to promote the degradation of the film. Tafel results show that PEO treatment decreases the corrosion current density by four, even five orders of magnitude, while additives content does not affect strongly the electrochemical corrosion behavior. Salt spray test shows that the PEO film formed with NaAlO{sub 2} and Na{sub 2}SiO{sub 3} presents good corrosion resistance, over 600 h without any sealing treatment. The difference of corrosion resistance arose by additives examined by electrochemical techniques and salt spray test does not show strict corresponding relationship. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

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

    Science.gov (United States)

    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. © 2014 Wiley Periodicals, Inc.

  13. Unravelling the magmatic system beneath a monogenetic volcanic complex (Jagged Rocks Complex, Hopi Buttes, AZ, USA)

    Science.gov (United States)

    Re, G.; Palin, J. M.; White, J. D. L.; Parolari, M.

    2017-12-01

    The Jagged Rocks complex is the eroded remnant of the plumbing systems of closely spaced monogenetic alkaline volcanic centres in the southern Hopi Buttes Volcanic Field (AZ, USA). It contains different clinopyroxene populations with distinctive textures and geochemical patterns. In the Northwestern part of the complex, which exposes the best developed system of conduits, most of the clinopyroxenes consist of large- to medium-sized resorbed cores overgrown by euhedral rims (type 1), small moderately resorbed greenish cores with the same overgrown rims (type 2), and phlogopite as an accessory phase. By contrast, in the Southern part of the complex the majority of clinopyroxenes are euhedral with oscillatory zonation (type 3) and are accompanied by minor euhedral olivine. The differences between these mineral assemblages indicate a composite history of crystallization and magmatic evolution for the two parts of the complex, governed by different mechanisms and ascent patterns from a single source at 50 km depth (16 kbar). The Northwest system preserves a high-pressure assemblage that cooled rapidly from near-liquidus conditions, suggesting direct ascent from the source to the surface at high-to-moderate transport rates (average 1.25 m/s). By contrast, the Southern system represents magma that advanced upward at much lower overall ascent rates, stalling at times to form small-volume mid-crustal storage zones (e.g., sills or a network of sheeted intrusions); this allowed the re-equilibration of the magma at lower pressure ( 30 km; 8 kbar), and led to nucleation and growth of euhedral clinopyroxene and olivine phenocrysts.

  14. Orientation dependent slip and twinning during compression and tension of strongly textured magnesium AZ31 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Al-Samman, T., E-mail: al-samman@imm.rwth-aachen.de [Institut fuer Metallkunde und Metallphysik, RWTH Aachen, Kopernikusstr. 14, D-52064 Aachen (Germany); Li, X. [Institut fuer Metallkunde und Metallphysik, RWTH Aachen, Kopernikusstr. 14, D-52064 Aachen (Germany); Chowdhury, S. Ghosh [CSIR National Metallurgical Laboratory, MST Division, Jamshedpur 831007 (India)

    2010-06-15

    Over recent years there have been a remarkable number of studies dealing with compression of magnesium. A literature search, however, shows a noticeably less number of papers concerned with tension and a very few papers comparing both modes, systematically, in one study. The current investigation reports the anisotropic deformation behavior and concomitant texture and microstructure evolution investigated in uniaxial tension and compression tests in two sample directions performed on an extruded commercial magnesium alloy AZ31 at different Z conditions. For specimens with the loading direction parallel to the extrusion axis, the tension-compression strength anisotropy was pronounced at high Z conditions. Loading at 45{sup o} from the extrusion axis yielded a tension-compression strength behavior that was close to isotropic. During tensile loading along the extrusion direction the extrusion texture resists twinning and favors prismatic slip (contrary to compression). This renders the shape change maximum in the basal plane and equal to zero along the c-axis, which resulted in the orientation of individual grains remaining virtually intact during all tension tests at different Z conditions. For the other investigated sample direction, straining was accommodated along the c-axis, which was associated with a lattice rotation, and thus, a change of crystal orientation. Uniaxial compression at a low Z condition (400 deg. C/10{sup -4} s{sup -1}) yielded a desired texture degeneration, which was explained on the basis of a more homogeneous partitioning of slip systems that reduces anisotropy and enhanced dynamic recrystallization (DRX), which counteracts the strong deformation texture. The critical strains for the nucleation of DRX in tensiled specimens at the highest investigated Z condition (200 deg. C/10{sup -2} s{sup -1}) were found to range between 4% and 5.6%.

  15. Study with a steam tracer in a zone near well Az-64, in the Los Azufres geothermal field, Mich.; Estudio con un trazador de vapor en la zona aledana al pozo Az-64, en el campo geotermico de Los Azufres, Mich.

    Energy Technology Data Exchange (ETDEWEB)

    Iglesias, Eduardo R. [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)]. E-mail: iglesias@iie.org.mx; Flores Armenta, Magaly; Quijano Leon, Jose Luis; Torres Rodriguez, Marco A. [Comision Federal de Electricidad, Gerencia de Proyectos Geotermoelectricos, Morelia, Michoacan (Mexico); Torres, Rodolfo J.; Reyes Picasso, Neftali [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Sandoval Medina, Fernando [Comision Federal de Electricidad, Gerencia de Proyectos Geotermoelectricos, Morelia, Michoacan (Mexico)

    2009-01-15

    A previous tracer study in the Maritaro-La Cumbre area of the Los Azufres, Mich., geothermal field concluded that injection in well Az-15 recharges a group of producing wells located east of the injector to a maximum distance of about 2000 m. The study also indicated injection in Az-15 either does not recharge wells farther east in the neighborhood of the Laguna Verde fault, or does so at very low rates over a long period. Because it is important to recharge this zone, it was decided to explore the possibility of doing it by injecting in well Az-64, located in the area. Thus the present study was designed. Six producing wells were chosen to monitor tracer arrivals. Because all the chosen wells produce steam (several also produce water) and for economic reasons, it was decided to use a steam-phase tracer. We chose sulfur hexafluoride (SF6), a tracer successfully used before in the field. On October 24, 2006, we injected 96.4 kg of SF6 into well Az-64. All six chosen wells were sampled for 156 days, starting the day of injection. The tracer was detected in all six wells and for every well the shape of the residence curve clearly depicted the fractured nature of the corresponding permeability. Again in every case, the recovery curves indicated recovery was completed within the 156-day sampling period. The largest recoveries were in wells Az-05 (48.5%) and Az-43 (1.27%), those closest to the injection well and on the same side of the Maritaro fault as Az-64. Well Az-51, lying at 848 m from the injector and farthest away, registered the third-highest recovery percentage (1.01 x 10-5%), significantly higher than well Az-19 (6.95 x 10-6%), located 490 m from the injector; the two wells are on the same side of the Maritaro fault as Az-64. Well Az-32, located 423 m from the injector, but on the other side of the Maritaro fault, recovered 5.6 x 10-7% of the injected tracer, comparable to 8.67 x 10-7%, the amount recovered in well Az-13 on the same side of the Maritaro fault

  16. The Schizosaccharomyces pombe JmjC-protein, Msc1, prevents H2A.Z localization in centromeric and subtelomeric chromatin domains.

    Directory of Open Access Journals (Sweden)

    Luke Buchanan

    2009-11-01

    Full Text Available Eukaryotic genomes are repetitively packaged into chromatin by nucleosomes, however they are regulated by the differences between nucleosomes, which establish various chromatin states. Local chromatin cues direct the inheritance and propagation of chromatin status via self-reinforcing epigenetic mechanisms. Replication-independent histone exchange could potentially perturb chromatin status if histone exchange chaperones, such as Swr1C, loaded histone variants into wrong sites. Here we show that in Schizosaccharomyces pombe, like Saccharomyces cerevisiae, Swr1C is required for loading H2A.Z into specific sites, including the promoters of lowly expressed genes. However S. pombe Swr1C has an extra subunit, Msc1, which is a JumonjiC-domain protein of the Lid/Jarid1 family. Deletion of Msc1 did not disrupt the S. pombe Swr1C or its ability to bind and load H2A.Z into euchromatin, however H2A.Z was ectopically found in the inner centromere and in subtelomeric chromatin. Normally this subtelomeric region not only lacks H2A.Z but also shows uniformly lower levels of H3K4me2, H4K5, and K12 acetylation than euchromatin and disproportionately contains the most lowly expressed genes during vegetative growth, including many meiotic-specific genes. Genes within and adjacent to subtelomeric chromatin become overexpressed in the absence of either Msc1, Swr1, or paradoxically H2A.Z itself. We also show that H2A.Z is N-terminally acetylated before, and lysine acetylated after, loading into chromatin and that it physically associates with the Nap1 histone chaperone. However, we find a negative correlation between the genomic distributions of H2A.Z and Nap1/Hrp1/Hrp3, suggesting that the Nap1 chaperones remove H2A.Z from chromatin. These data describe H2A.Z action in S. pombe and identify a new mode of chromatin surveillance and maintenance based on negative regulation of histone variant misincorporation.

  17. Influencia de compuestos azúcares y no azúcares en la calidad industrial de caña de azúcar en Tucumán, R. Argentina: caña verde y quemada (Parte 2 Effect of sugar and non sugar compounds on sugar cane industrial quality in Tucumán (Argentina

    Directory of Open Access Journals (Sweden)

    B. Silvia Zossi

    2011-06-01

    Full Text Available A partir de 1997 en Tucumán, R. Argentina, entre el 65% y el 85% de la caña destinada a la producción de azúcar se cosecha en verde o quemada, mediante el sistema de cosecha integral. El resto del cultivo se cosecha en forma semimecánica, con un predominio del uso de la quema, del corte manual y carguío mecánico. La quema de caña, antes o después de ser cosechada, se realiza para remover las hojas adheridas a sus tallos, minimizando así el ingreso de no azúcares a la fábrica. Desde el año 2005, debido a disposiciones legislativas, la cosecha de caña en verde fue aumentando gradualmente, lo que incrementó considerablemente la concentración de compuestos no azúcares en el proceso de elaboración de azúcar. Por ello se decidió evaluar los principales componentes azúcares y no azúcares, especialmente los formadores de color, y su influencia en el proceso fabril de las cuatro variedades comerciales más difundidas en la provincia: TUCCP 77-42, LCP 85-384, CP 65-357 y RA 87-3, cosechadas de tres maneras diferentes: tallo molible limpio, despuntado y sin hojas; caña quemada para eliminar las hojas y despuntada y caña cosechada en verde, con un 15% de "trash" (hojas y despunte aproximadamente. En este trabajo se presentan los datos obtenidos con cosecha en verde y quemada. Los resultados mostraron que la variedad LCP 85-384 es la que presentó el mejor comportamiento para la producción de azúcar, por su mayor contenido de este sacárido y menores tenores de fibra y compuestos no azúcares, independientemente del tipo de cosecha. En las cuatro variedades estudiadas, disminuyeron la extracción de jugo y la cantidad de azúcar recuperable en fábrica y se incrementaron los contenidos de compuestos no azúcares, principalmente almidón y cenizas, cuando se trabajó con caña cosechada en verde.Since 1997 in Tucumán, Argentina, between 65% and 85% of cane for sugar production has been harvested mechanically, either green or burnt

  18. Dual RNA-Seq of Lysobacter capsici AZ78 - Phytophthora infestans interaction shows the implementation of attack strategies by the bacterium and unsuccessful oomycete defense responses.

    Science.gov (United States)

    Tomada, Selena; Sonego, Paolo; Moretto, Marco; Engelen, Kristof; Pertot, Ilaria; Perazzolli, Michele; Puopolo, Gerardo

    2017-10-01

    Biological interactions in the microbial communities of the rhizosphere continuously shape the gene expression patterns of each individual microorganism. A dual RNA-Seq approach was applied to obtain a comprehensive overview of the molecular mechanisms activated during the interaction between the biocontrol rhizobacterium Lysobacter capsici AZ78 and the soilborne phytopathogenic oomycete Phytophthora infestans. The RNA-Seq transcriptional profile of L. capsici AZ78 was characterized by up-regulation of genes concerned in the biogenesis of type 4 pilus and lytic enzymes, involved, respectively, in host colonization and subsequent attack of the P. infestans cell wall. The activation of detoxification processes allowed L. capsici AZ78 to overcome the attempted defense processes of P. infestans. Moreover, the genes involved in antibiotic biosynthesis were up-regulated in L. capsici AZ78 and caused cell death in P. infestans, with the activation of putative apoptotic processes. The consequences of P. infestans cell death resulted in the down-regulation of primary metabolic pathways, such as carbohydrates, nucleic acids and protein metabolisms. Overall, the mechanism of action of L. capsici AZ78 was related to parasitism and predatory activities that cause the death of P. infestans. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  19. Monitoring Lysobacter capsici AZ78 using strain specific qPCR reveals the importance of the formulation for its survival in vineyards.

    Science.gov (United States)

    Segarra, Guillem; Puopolo, Gerardo; Porcel-Rodríguez, Elena; Giovannini, Oscar; Pertot, Ilaria

    2016-02-01

    Survival in the phyllosphere is a critical feature for biofungicides based on non-spore forming bacteria. Moreover, knowledge of their persistence on plants is important to design effective formulations and application techniques. With this scope, the aim of this work was to develop a specific method to monitor the fate in the environment of Lysobacter capsici AZ78, a biocontrol agent of Plasmopara viticola, and to evaluate the contribution of formulation in its persistence on grapevine leaves. A strain-specific primer pair derived from REP-PCR fingerprinting was used in quantitative PCR experiments to track the evolution of L. capsici AZ78 population in vineyards. The population reached between 5 and 6 log10 cells gram of leaf(-1) after application and decreased by more than 100 times in one week. Multiple regression analysis showed that unfavourable temperature was the main environmental factor correlating with the decrease of L. capsici AZ78 persistence on grapevine leaves. Importantly, the use of formulation additives protected L. capsici AZ78 against environmental factors and improved its persistence on the leaves by more than 10 times compared to nude cells. Formulation and the knowledge about the persistence of L. capsici AZ78 in vineyards will be useful to develop commercial biofungicides for foliar application. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Nano-hydroxyapatite reinforced AZ31 magnesium alloy by friction stir processing: a solid state processing for biodegradable metal matrix composites.

    Science.gov (United States)

    Ratna Sunil, B; Sampath Kumar, T S; Chakkingal, Uday; Nandakumar, V; Doble, Mukesh

    2014-04-01

    Friction stir processing (FSP) was successfully adopted to fabricate nano-hydroxyapatite (nHA) reinforced AZ31 magnesium alloy composite as well as to achieve fine grain structure. The combined effect of grain refinement and the presence of embedded nHA particles on enhancing the biomineralization and controlling the degradation of magnesium were studied. Grain refinement from 56 to ~4 and 2 μm was observed at the stir zones of FSP AZ31 and AZ31-nHA composite respectively. The immersion studies in super saturated simulated body fluid (SBF 5×) for 24 h suggest that the increased wettability due to fine grain structure and nHA particles present in the AZ31-nHA composite initiated heterogeneous nucleation which favored the early nucleation and growth of calcium-phosphate mineral phase. The nHA particles as nucleation sites initiated rapid biomineralization in the composite. After 72 h of immersion the degradation due to localized pitting was observed to be reduced by enhanced biomineralization in both the FSPed AZ31 and the composite. Also, best corrosion behavior was observed for the composite before and after immersion test. MTT assay using rat skeletal muscle (L6) cells showed negligible toxicity for all the processed and unprocessed samples. However, cell adhesion was observed to be more on the composite due to the small grain size and incorporated nHA.

  1. High performance corrosion and wear resistant composite titanium nitride layers produced on the AZ91D magnesium alloy by a hybrid method

    Directory of Open Access Journals (Sweden)

    Michał Tacikowski

    2014-09-01

    Full Text Available Composite, diffusive titanium nitride layers formed on a titanium and aluminum sub-layer were produced on the AZ91D magnesium alloy. The layers were obtained using a hybrid method which combined the PVD processes with the final sealing by a hydrothermal treatment. The microstructure, resistance to corrosion, mechanical damage, and frictional wear of the layers were examined. The properties of the AZ91D alloy covered with these layers were compared with those of the untreated alloy and of some engineering materials such as 316L stainless steel, 100Cr6 bearing steel, and the AZ91D alloy subjected to commercial anodizing. It has been found that the composite diffusive nitride layer produced on the AZ91D alloy and then sealed by the hydrothermal treatment ensures the corrosion resistance comparable with that of 316L stainless steel. The layers are characterized by higher electrochemical durability which is due to the surface being overbuilt with the titanium oxides formed, as shown by the XPS examinations, from titanium nitride during the hydrothermal treatment. The composite titanium nitride layers exhibit high resistance to mechanical damage and wear, including frictional wear which is comparable with that of 100Cr6 bearing steel. The performance properties of the AZ91D magnesium alloy covered with the composite titanium nitride coating are substantially superior to those of the alloy subjected to commercial anodizing which is the dominant technique employed in industrial practice.

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

    Science.gov (United States)

    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. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Wei; Zhang, Guangdao [Department of Prosthodontics, School of Stomatology, China Medical University, Shenyang 110001 (China); Tan, Lili; Yang, Ke [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Ai, Hongjun, E-mail: aihongjuna@sina.com [Department of Prosthodontics, School of Stomatology, China Medical University, Shenyang 110001 (China)

    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. - Highlights: • Fluoride coating inhibited the degradation of the alloy in the early implantation. • Fluorine coating could slow down the rate of Mg corrosion and Mg ion release. • Fluorine coating could promote the deposition of Ca and P in vivo. • Fluorine coated Mg alloy had well osteogenic activity and biocompatibility. • Fluorine coating up-regulated the expression of BMP-2 and collagen type I protein.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rojaee, Ramin, E-mail: raminrojaee@aim.com [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan (Iran, Islamic Republic of); Raeissi, Keyvan [Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 (Iran, Islamic Republic of)

    2013-10-15

    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{sup 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{sup 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. - Highlights: • Nanostructured hydroxyapatite coatings were applied on Mg based alloy. • The whole corrosion process of Mg based alloy was controlled in body fluid. • This coating was able to act as a barrier against further release of Mg{sup 2+} ions. • The coating improved the stabilization of Mg alkalization behavior.

  5. El Palacio Domecq de Jerez de la Frontera y el arquitecto Juan Díaz de la Guerra

    Directory of Open Access Journals (Sweden)

    José Manuel Moreno Arana

    2014-01-01

    Full Text Available Estudio sobre el Palacio Domecq de Jerez de la Frontera (Cádiz, España, la más impor- tante de las casas señoriales construidas durante el siglo XVIII en dicha ciudad. Junto a su análisis formal, se aportan detalles sobre su promotor, el marqués de Montana, y su proceso constructivo, documentando la intervención del arquitecto Juan Díaz de la Guerra, del que se suministran también nuevos datos biográ cos y profesionales.

  6. CYCLIC PLASTIC BEHAVIOR AND FATGIUE LIFE OF AZ91 ALLOY IN AS-CAST AND ULTRAFINE-GRAINED STATE

    Directory of Open Access Journals (Sweden)

    Stanislava Fintová

    2014-06-01

    Full Text Available Fatigue properties of magnesium alloy AZ91 in as-cast and in ultrafine-grained state prepared by equal channel angular pressing were investigated. The fatigue strength in the low-cycle fatigue region was found to be substantially improved by the severe plastic deformation, whereas the improvement in the high-cycle fatigue region is negligible. The cyclic plastic response in both states is qualitatively similar; short initial softening is followed by a long cyclic hardening. The observed fatigue behavior was discussed in terms of specific microstructural features of both states and on the basis of cyclic slip localization and fatigue crack initiation. 

  7. Diffusion Bonding Behavior and Characterization of Joints Made Between 316L Stainless Steel Alloy and AZ31 Magnesium Alloy

    Science.gov (United States)

    Elthalabawy, Waled Mohamed

    The 316L austenitic stainless steel and AZ31 magnesium alloy have physical and mechanical properties which makes these alloys suitable in a number of high technology based industries such as the aerospace and automotive sectors. However, for these alloys to be used in engineering applications, components must be fabricated and joined successfully. The differences in the physical and metallurgical properties between these two alloys prevents the use of conventional fusion welding processes commonly employed in aerospace and transport industry. Therefore, alternative techniques need to be developed and diffusion bonding technology is a process that has considerable potential to join these two dissimilar alloys. In this research work both solid-state and transient liquid phase (TLP) bonding processes were applied. The solid-state bonding of 316L steel to AZ31 magnesium alloy was possible at a bonding temperature of 550°C for 120 minutes using a pressure of 1.3 MPa. The interface characterization of the joint showed a thin intermetallic zone rich in Fe-Al was responsible for providing a metallurgical bond. However, low joint shear strengths were recorded and this was attributed to the poor surface to surface contact. The macro-deformation of the AZ31 alloy prevented the use of higher bonding pressures and longer bonding times. In order to overcome these problems, the TLP bonding process was implemented using pure Cu and Ni foils as interlayers which produced a eutectic phase at the bonding temperature. This research identified the bonding mechanism through microstructural and differential scanning calorimetry investigations. The microstructural characterization of the TLP joints identified intermetallics which became concentrated along the 316L steel/AZ31 bond interface due to the "pushing effect" of the solid/liquid interface during isothermal solidification stage of bonding. The size and concentration of the intermetallics had a noticeable effect on the final joint

  8. Stress Corrosion Cracking Behavior of Fine-Grained AZ61 Magnesium Alloys Processed by Equal-Channel Angular Pressing

    OpenAIRE

    Qiuyuan Xie; Aibin Ma; Jinghua Jiang; Zhaojun Cheng; Dan Song; Yuchun Yuan; Huan Liu

    2017-01-01

    The effect of equal-channel angular pressing (ECAP) on stress corrosion cracking (SCC) behavior of a cast AZ61 Mg alloy was investigated in distilled water (DW) using the slow strain rate tensile test (SSRT) at a strain rate of 1 × 10−6 s−1. The fine-grained alloy after ECAP showed a greater SCC susceptibility but a higher ultimate tensile strength, compared with the as-cast counterpart. The results were attributed to refined grains, high-density dislocations and increased proportion of high-...

  9. Galvanic corrosion of rare earth modified AM50 and AZ91D magnesium alloys coupled to steel and aluminium alloys

    Directory of Open Access Journals (Sweden)

    Mohedano, Marta

    2014-03-01

    Full Text Available Electrochemical and gravimetric measurements were used to examine the effects of neodymium and gadolinium additions on the galvanic corrosion behaviour of AM50 and AZ91D magnesium alloys coupled to A 570 Gr 36 carbon steel and AA2011-AA6082 aluminium alloys. Rare earth modified alloys showed Al2Nd/Al2Gd and Al-Mn-Nd/Al-Mn-Gd intermetallics, reduced area fraction of β-Mg17Al12 phase and increased corrosion resistance due to increased surface passivity and suppression of micro-galvanic couples. Neodymium and gadolinium additions improved the galvanic corrosion resistance of AM50 alloy, but were less effective in case of the AZ91D alloy. The AA6082 alloy was the most compatible material and the AA2011 alloy was the least compatible.Se emplearon medidas electroquímicas y gravimétricas para examinar el efecto de la adición de neodimio y gadolinio en el comportamiento a la corrosión galvánica de las aleaciones AM50 y AZ91D en contacto con acero al carbono A 570 Gr 36 y aleaciones de aluminio AA2011 y AA6082. Las aleaciones modificadas con tierras raras mostraron intermetálicos Al2Nd/Al2Gd y Al-Mn-Nd/Al-Mn-Gd, menor fracción de fase β-Mg17Al12 y un incremento de la resistencia a la corrosión debido al aumento de la pasividad de la superficie y a la eliminación de micro pares galvánicos. Las adiciones de neodimio y gadolinio mejoraron la resistencia a la corrosión galvánica de la aleación AM50, pero fueron menos efectivas en el caso de la aleación AZ91D. La aleación AA6082 fue el material más compatible y la aleación AA2011 el menos compatible.

  10. Low cycle fatigue properties and an energy-based approach for as-extruded AZ31 magnesium alloy

    Science.gov (United States)

    Kwon, S. H.; Song, K. S.; Shin, K. S.; Kwun, S. I.

    2011-04-01

    Low cycle fatigue tests were conducted to investigate the cyclic deformation behavior and the energy-based criterion of AZ31 magnesium alloy. The alloy exhibited an asymmetric hysteresis loop due to the twinning and detwinning effect. The cyclic stress responses showed cyclic hardening at all total strain amplitudes. To evaluate the plastic strain energy, the Halford-Morrow equation and a modified equation for magnesium alloy were compared. The effect of twinning on the total plastic strain energy dissipated during fatigue life was discussed. The variations of the twin and dislocation densities were also investigated using optical microscopy and transmission electron microscopy, respectively.

  11. Azúcar agridulce: trabajo y sindicatos en la agroindustria azucarera colombiana, 1960-1980

    Directory of Open Access Journals (Sweden)

    Juan Sebastián Marulanda Restrepo

    2012-07-01

    Full Text Available

    Resumen

    Esta investigación reconstruye el contexto laboral de los obreros en la agroindustria azucarera en Colombia entre los años de 1960 y 1980, un periodo de cambios profundos en las condiciones del trabajo de los trabajadores azucareros por cuenta de las transformaciones en este particular tipo de industria. Entre estas deben citarse hechos como la introducción de nuevas tecnologías en el cultivo de la caña y el incremento de la necesidad de mano de obra, producto de la expansión de las zonas cultivadas y al aumento de la producción, debidas a la apertura de mercados como Estados Unidos, cerrados al azúcar cubano a causa de la Revolución. Por otro lado, el sindicalismo azucarero estuvo inmerso en contradicciones que hicieron problemática la cohesión entre las diferentes organizaciones. En síntesis, las circunstancias mencionadas modificaron sustancialmente el panorama laboral de los obreros azucareros.

     

    Palabras claves: obreros azucareros, industria azucarera, ingenios, salarios, sindicatos.

     

    Abstract

    This investigation reconstruct the employment context of the workers in the sugar industry in Colombia between 1960 and 1980, a period of profound changes in conditions of sugar workers on account of the transformations in this particular kind of industry. Between these transformations must be mentioned facts as the introduction of new technologies in the cane farming and the increase of need of farm workers, due to the expansion of cane farms and the rise of sugar production, because of the openness of markets such as United States, closed to cuban sugar because of the Revolution. On the other hand, the sugar labor union movement was immersed in contradictions that were problematic the unity between different organizations. In short, the mentioned circumstances substantially

  12. A study of deformation twinning in magnesium alloy AZ31B

    Science.gov (United States)

    Majkut, Marta

    Crystals with a hexagonal close-packed crystal structure are inherently anisotropic, and have a limited number of independent slip systems, which lead to strong deformation textures and reduced formability in polycrystalline products. In magnesium (Mg), all of the easy slip systems have a Burgers vector in the direction making twinning necessary for arbitrary shape changes. The most common twinning system which allows extension along the c-axis is {1012}. A good predictor of slip is the global Schmid factor, which resolves the externally applied force onto the slip plane and direction of a crystal. The critically resolved shear stress (CRSS) at which a grain twins is not readily measured by experiment and the CRSS for twin initiation often appears larger than for twin propagation. In polycrystals, twin variants with both low and high Schmid factors have been observed indicating that this Schmid factor is inappropriate to predict twinning and more local effects play an important, though still uncertain role. In this work, experiments were devised to dynamically study extension twinning in a polycrystalline Mg alloy AZ31B with a strong basal rolling texture by tensile deformation parallel to the plate normal. Three-dimensional X-ray diffraction using a synchrotron source was used to map the centre-of-mass positions, orientations, and grain-resolved elastic strain tensors of over 1000 grains in-situ up to a true strain of 1.4%. The majority of twins formed in grains with a high local Schmid factor; however, low-ranked twin variants were common. The average grain-resolved stress did not always select the highest twin variant and resulted in some negative Schmid factors. The internal stress state of parent grains and twinned grains did not differ significantly within the large measurement uncertainties. The misorientations between grains ideally oriented for twinning and their nearest neighbours could not explain cases of no twin activity. Results suggest that the

  13. Justas, fiestas y protagonismos: Alegrías y placeres en El Victorial de Gutierre Díaz de Games = Jousting, Festivities and Prominence: Joy and Pleasures in Gutierre Díaz de Games’s El Victorial

    Directory of Open Access Journals (Sweden)

    María del Pilar Rábade Obradó

    2016-06-01

    Full Text Available Este trabajo pretende analizar cómo se reflejan dos emociones básicas, la alegría y el placer, en una crónica del siglo XV, concretamente El Victorial de Gutierre Díaz de Games. Como se trata de una biografía caballeresca, en sus páginas se plasma una visión particular de las dos citadas emociones. Así, la crónica ofrece un elenco de aquellas circunstancias en las que se suponía que los caballeros estaban en situación de experimentar el placer y la alegría. Esas circunstancias van desde las fiestas cortesanas hasta las victorias en batallas, sin olvidar el amor y la amistad.The purpose of this article is to analyze how two basic emotions like joy and pleasure were expressed in a fifteenth-century chronicle, namely El Victorial by Gutierre Díaz de Games. Since the chronicle is a chivalric biography, its pages highlight a particular vision of joy and pleasure. Consequently, the chronicle offers a variety of circumstances in which knights were meant to experience pleasure and happiness. These circumstances range from court festivities to victories in battles, as well as those involving love and friendship.

  14. Korunk fő fejlődési tendenciái az élelmiszer-termelésben, különös tekintettel az állati termékekre

    OpenAIRE

    Horn, Péter

    2013-01-01

    A szerző több prognózist közöl, amelyek az állati termékek iránti megnövekedett kereslet várható mértékét körvonalazzák, egyúttal bemutatja a szükséges növényi többletbiomassza-igényt is, amely a következő évtizedekben várható, és amelynek célja egyrészt az emberi élelmiszer-ellátás biztosítása, másrészt a növekvő állatállomány takarmányigényének kielégítése, külön feltüntetve a bioüzemanyag-ipar várható növekvő igényeit is, amennyiben a jelenlegi technológiákat nem váltják fel alapvetően úja...

  15. AZ-2000-IECW and StaMet Black Kapton Options for Solar Probe Plus MAG Sensor MLI Kevlar/Polyimide Shells

    Science.gov (United States)

    Choi, Michael K.

    2017-01-01

    AZ-2000-IECW white paint and StaMet black Kapton have been evaluated for the Kevlar/polyimide shells that enclose the Solar Probe Plus Magnetometer (MAG) sensors and multilayer insulation. Flight qualification testing on AZ-2000-IECW painted Kevlar/polyimide laminate was completed at Goddard Space Flight Center. This paint potentially meets all the requirements. However, it has no flight heritage. StaMet is hotter in the sun, and is specular. The results of the MAG thermal balance test show StaMet meets the thermal requirement and heater power budget. The mission prefers to fly StaMet after evaluating the risks of AZ-2000-IECW flaking and glint from StaMet to the Star Trackers.

  16. Interfacial Reaction Characteristics and Mechanical Properties of Welding-brazing Bonding Between AZ31B Magnesium Alloy and PRO500 Ultra-high Strength Steel

    Directory of Open Access Journals (Sweden)

    CHEN Jian-hua

    2017-11-01

    Full Text Available Experiments were carried out with TIG welding-brazing of AZ31B magnesium alloy to PRO500 steel using TIG arc as heat source. The interfacial reaction characteristics and mechanical properties of the welding-brazing bonding were investigated. The results show that an effective bonding is achieved between AZ31B magnesium alloy and PRO500 steel by using TIG welding-brazing method. Some spontaneous oxidation reactions result in the formation of a transition zone containing AlFe3 phase with rich oxide. The micro-hardness value of the interfacial transition zone is between that of the AZ31B and the PRO500. Temper softening zone appears due to the welding thermal cycle nearby the bonding position in the interface. A higher heat input makes an increase of the brittle phases and leads to an obvious decrease of the bonding strength.

  17. AZ17: a new bispecific drug targeting IL-6 and IL-23 with potential clinical use-improves psoriasis in a human xenograft transplantation model

    DEFF Research Database (Denmark)

    Stenderup, Karin; Kjeldsen, Cecilia Rosada; Shanebeck, K

    2015-01-01

    ; widely accepted to be associated with psoriasis. To meet the need for new therapeutics, we aimed to create a clinically relevant bispecific drug, by combining the inhibitory properties of anti-IL-6 and anti-IL-23 antibodies, exhibiting high affinity, high stability and the ability to be produced in high...... yield. The bispecific molecule AZ17 was created by combining high affinity binding domains originating from monoclonal antibodies targeting human IL-6 and IL-23. To allow for high and efficient production, AZ17 was assembled by site-specific bioconjugation from two individual single chain fragment...... model where psoriasis skin is transplanted onto immune-deficient mice. The data presented here suggest AZ17 to be a promising drug candidate in psoriasis and other inflammatory diseases associated with Th17 cell development....

  18. Structural and electrochemical behavior of sol-gel ZrO{sub 2} ceramic film on chemically pre-treated AZ91D magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li Qing [School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)], E-mail: liqingd@swu.edu.cn; Chen Bo; Xu Shuqiang; Gao Hui; Zhang Liang; Liu Chao [School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2009-06-10

    In the present investigation sol-gel-based ZrO{sub 2} ceramic film was obtained using zirconium acetate as the precursor material. The film was deposited on AZ91D magnesium alloy by a dip-coating technique. An uniform stannate conversion coating as chemical pretreatment was employed as an intermediate layer prior to deposition of the ZrO{sub 2} film in order to provide advantage for the formation of sol-gel-based ZrO{sub 2} layer. The corrosion properties, structure, composition and morphology of these coatings on AZ91D magnesium alloy were studied by potentiodynamic polarization tests, EIS, XRD, SEM, respectively. According to the electrochemical tests, the corrosion resistance of AZ91D magnesium alloy was found to be greatly improved by means of this new environment-friendly surface treatment.

  19. The Analysis of Narrative structure of Bad Az Payan novel by Fariba Vafi

    Directory of Open Access Journals (Sweden)

    Teymoor Malmir

    2017-08-01

    Full Text Available Abstract Feriba Vafi is a hard working novelist of our time. Her first novel was ‘My bird’ has been worried to alleviate the plight of women in the society. In her last novel by the name of ‘bad az payan’ she deals with women issue continuously. But to intensify the effective ness of the story in the community and proper to time condition besides the choice of subject, she has used plot, signs and particular way of telling narrative. In this paper based on the account of Todorov analyzes we study the thematic link, plot and the way of telling narrative. The actions and reactions of characters in the novel ‘bad az payan’ represent an attempt, consciously or unconsciously, more or less, to recover and to reconstruct women’s identity. The plot reflectively addresses the social and partly the familial problems of the community of women. In this novel, the journey leitmotif serves to portray a departure to independence, knowledge and a better life; yet the problems persist and the journey continues, a journey which is associated with solitude and disorderliness. Notwithstanding, the journey is an ‘evasion, as the journey of the characters of the novel is represented as an evasion, in one way or another. Men and women set out the journey hoping to find a better situation, leaving a self-made bitter situation. The narration of Shahrzad in ‘hezar-o yek shab’ has dramatically influenced this novel in terms of such elements of narration as the use of subplots, multiple narrators, which serve to highlight narration as opposed to verbose ‘story-telling’ with which men identify women. That is to say, the type of narration invoked by women is distinct from that of men; this distinction, on the one hand, represents an old style which has bolstered the retention and survival of women, on the other, it represents a mockery towards the masculine world. It, therefore, implies that the reason why women have adopted a narrative discourse is

  20. Test-retest reliability of [{sup 11}C]AZ10419369 binding to 5-HT{sub 1B} receptors in human brain

    Energy Technology Data Exchange (ETDEWEB)

    Nord, Magdalena; Finnema, Sjoerd J.; Schain, Martin; Halldin, Christer; Farde, Lars [Karolinska Institutet, Center for Psychiatric Research, R5:00, Karolinska University Hospital, Department of Clinical Neuroscience, Stockholm (Sweden)

    2014-02-15

    [{sup 11}C]AZ10419369 is a recently developed 5-HT{sub 1B} receptor radioligand that is sensitive to changes in endogenous serotonin concentrations in the primate brain. Thus, [{sup 11}C] AZ10419369 may serve as a useful tool in clinical studies of the pathophysiology and pharmacological treatment of diseases related to the serotonin system, such as depression and anxiety disorders. The aim of this study was to evaluate the test-retest reliability of [{sup 11}C]AZ10419369. Eight men were examined with PET and [{sup 11}C] AZ10419369 twice on the same day. The binding potentials (BP{sub ND}) of [{sup 11}C]AZ10419369 in selected serotonergic projection areas and in the raphe nuclei (RN) were determined using the simplified reference tissue model, and for comparison also using a wavelet-aided parametric imaging approach. The BP{sub ND} values obtained from the first and second PET scans were compared by means of descriptive statistics, difference, absolute variability and intraclass correlation coefficient. Similar BP{sub ND} values were obtained with the two methods. The absolute mean differences in BP{sub ND} between PET 1 and PET 2 were less than 3 % in all serotonergic projection regions. Absolute variabilities were low in cortical regions (5 - 7 %), low to moderate (7 - 14 %) in subcortical regions, but higher (20 %) in the RN. The BP{sub ND} of [{sup 11}C]AZ10419369 is highly reproducible in cortical regions and satisfactory in subcortical projection areas. The variability in the RN is higher. Thus larger sample sizes or larger divergences are required to assess a potential difference between subjects or between experimental conditions in this region. (orig.)

  1. Dynamic behaviors of a Ca-P coated AZ31B magnesium alloy during in vitro and in vivo degradations

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qiang [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Tan Lili, E-mail: lltan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Xu Wenli; Zhang Bingchun [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Yang Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2011-12-15

    Surface modification can be an effective way to control the biodegradation behavior of magnesium alloys and even improve their biological properties. Much attention has been paid to the initial protection ability and biological properties of magnesium alloys coating. In this work, the dynamic behaviors of a Ca-P coated AZ31B magnesium alloy during the degradations in vitro and in vivo, including hemolysis, mechanical loading capability and implantation in animals, were investigated. The hemolytic rates of the alloy with and without coating were all declined to be lower than 5% after more than 20 days immersion in PBS, though an increase happened to the alloy at the early immersion of 3-7 days. Reduction of the mechanical loading capacity was gradually evolved for the coated alloy and the peak load retention of 85% was still maintained after 120 days degradation. The in vivo implantation indicated that the Ca-P coated AZ31B alloy showed a more suitable time dependent degradation behavior which was favorable for growth of the new tissue and the healing dynamics of bones, making it a promising choice for medical application.

  2. Effect of Rolling Route on Microstructure and Tensile Properties of Twin-Roll Casting AZ31 Mg Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Dan Luo

    2016-06-01

    Full Text Available Twin-roll casting AZ31 Mg alloy sheets have been fabricated by normal unidirectional-rolling, head-to-tail rolling, and clock-rolling, respectively. It has been demonstrated that head-to-tail rolling is the most effective to refine the microstructure and weaken the basal texture among the three rolling routes. Excellent integrated tensile properties can be obtained by the head-to-tail rolling. The yield strength, ultimate tensile strength, and plastic elongation are 196 MPa, 301 MPa, and 28.9%, respectively. The strength can benefit from the fine grains (average value of 4.0 μm of the AZ31 alloy processed by the head-to-tail rolling route, while the excellent plastic elongation is achieved owing to the weakened basal texture besides the fine grains. Results obtained here can be used as a basis for further study of some simple rolling methods, which is critical to the development of Mg alloys with high strength and plasticity.

  3. Fabrication of AZ31/MWCNTs Surface Metal Matrix Composites by Friction Stir Processing: Investigation of Microstructure and Mechanical Properties

    Science.gov (United States)

    Arab, Seyed Mohammad; Zebarjad, Seyed Mojtaba; Jahromi, Seyed Ahmad Jenabali

    2017-11-01

    The surface metal matrix composites of AZ31 Mg alloy reinforced with multiwall carbon nanotubes (MWCNTs) have been fabricated through the friction stir processing by a conventional and two stepped tools. The microstructure and mechanical properties of fabricated composites were studied by optical and electron microscopy, microhardness and tensile tests, respectively. The processing has developed a fine-grain structure along with good distribution of reinforcements. The hardness and tensile strength of fabricated MWCNT/AZ31 composites are generally higher than as-received and FSPed samples. The accumulative effect of grain refinement and reinforcing nanotubes is assumed to be the reason for increasing the ductility after friction stir processing. The hardness is nearly doubled for FSPed samples and some more for nanocomposites compared with the as-received sample. The elongation of nanocomposites is about two times greater than that of the as-rolled sample. The speed ratio, pass number and CNT amount are three important factors influencing the resulting microstructure and mechanical properties. The stepped tools also give a more uniform distribution of reinforcement and higher grain refinement.

  4. Wetting Behavior of Molten AZ61 Magnesium Alloy on Two Different Steel Plates Under the Cold Metal Transfer Condition

    Directory of Open Access Journals (Sweden)

    ZENG Cheng-zong

    2017-04-01

    Full Text Available The wetting behavior and interfacial microstructures of molten magnesium AZ61 alloy on the surface of two different Q235 and galvanized steel plates under the condition of cold metal transfer were investigated by using dynamic sessile drop method. The results show that the wetting behavior is closely related to the wire feed speed. Al-Fe intermetallic layer was observed whether the substrate is Q235 steel or galvanized steel, and the formation of Al-Fe intermetallic layer should satisfy the thermodynamic condition of such Mg-Al/Fe system. The wettability of molten AZ61 magnesium alloy is improved with the increase of wire feed speed whether on Q235 steel surface or on galvanized steel surface, good wettability on Q235 steel surface is due to severe interface reaction when wire feed speed increases, good wettability on galvanized steel surface is attributed to the aggravating zinc volatilization. When the wire feed speed is ≤10.5m·min-1, the wettability of Mg alloy on Q235 steel plate is better than on galvanized steel plate. However, Zn vapor will result in instability for metal transfer process.

  5. Corrosion protection and improved cytocompatibility of biodegradable polymeric layer-by-layer coatings on AZ31 magnesium alloys.

    Science.gov (United States)

    Ostrowski, Nicole; Lee, Boeun; Enick, Nathan; Carlson, Benjamin; Kunjukunju, Sangeetha; Roy, Abhijit; Kumta, Prashant N

    2013-11-01

    Composite coatings of electrostatically assembled layer-by-layer anionic and cationic polymers combined with an Mg(OH)2 surface treatment serve to provide a protective coating on AZ31 magnesium alloy substrates. These ceramic conversion coating and layer-by-layer polymeric coating combinations reduced the initial and long-term corrosion progression of the AZ31 alloy. X-ray diffraction and Fourier transform infrared spectroscopy confirmed the successful application of coatings. Potentiostatic polarization tests indicate improved initial corrosion resistance. Hydrogen evolution measurements over a 2 week period and magnesium ion levels over a 1 week period indicate longer range corrosion protection and retention of the Mg(OH)2 passivation layer in comparison to the uncoated substrates. Live/dead staining and DNA quantification were used as measures of biocompatibility and proliferation while actin staining and scanning electron microscopy were used to observe the cellular morphology and integration with the coated substrates. The coatings simultaneously provided improved biocompatibility, cellular adhesion and proliferation in comparison to the uncoated alloy surface utilizing both murine pre-osteoblast MC3T3 cells and human mesenchymal stem cells. The implementation of such coatings on magnesium alloy implants could serve to improve the corrosion resistance and cellular integration of these implants with the native tissue while delivering vital drugs or biological elements to the site of implantation. Copyright © 2013. Published by Elsevier Ltd.

  6. Estudio tribológico en chumaceras y ejes de molino de caña de azúcar

    Directory of Open Access Journals (Sweden)

    John Jairo Coronado

    2004-01-01

    Full Text Available Las chumaceras y los ejes de molino de caña de azúcar presentan fallas como: desgaste, fisuras y quemaduras. Un proyecto de investigación acerca de la tribología del par bronce-acero es realizado por la Escuela de Ingeniería Mecánica de la Universidad del Valle, junto con CENICAÑA y el Ingenio Manuelita, y se basa en la identificación del mecanismo de desgaste presente y en el análisis de las propiedades tribológicas de los elementos del par. Dentro del proyecto de investigación se diseñó y construyó un tribómetro de desgaste adhesivo normalizado tipo bloque–anillo, para reproducir las condiciones de operación de los molinos de caña y se ensayaron diferentes combinaciones de materiales para la chumacera: bronce SAE 67 y 64, con diferentes lubricantes: grasa y aceite. A través del uso de microscopia óptica y electrónica se pudo identificar el mecanismo de desgaste en bronces y guijos. De acuerdo a los resultados obtenidos se pudo concluir que la mejor combinación tribológica fue el par acero SAE 1045 – bronce SAE 64 y aceite como lubricante para los molinos de caña de azúcar.

  7. Electrochemical characteristics of calcium-phosphatized AZ31 magnesium alloy in 0.9 % NaCl solution.

    Science.gov (United States)

    Hadzima, Branislav; Mhaede, Mansour; Pastorek, Filip

    2014-05-01

    Magnesium alloys suffer from their high reactivity in common environments. Protective layers are widely created on the surface of magnesium alloys to improve their corrosion resistance. This article evaluates the influence of a calcium-phosphate layer on the electrochemical characteristics of AZ31 magnesium alloy in 0.9 % NaCl solution. The calcium phosphate (CaP) layer was electrochemically deposited in a solution containing 0.1 M Ca(NO3)2, 0.06 M NH4H2PO4 and 10 ml l(-1) of H2O2. The formed surface layer was composed mainly of brushite [(dicalcium phosphate dihidrate (DCPD)] as proved by energy-dispersive X-ray analysis. The surface morphology was observed by scanning electron microscopy. Immersion test was performed in order to observe degradation of the calcium phosphatized surfaces. The influence of the phosphate layer on the electrochemical characteristics of AZ31, in 0.9 % NaCl solution, was evaluated by potentiodynamic measurements and electrochemical impedance spectroscopy. The obtained results were analysed by the Tafel-extrapolation method and equivalent circuits method. The results showed that the polarization resistance of the DCPD-coated surface is about 25 times higher than that of non-coated surface. The CaP electro-deposition process increased the activation energy of corrosion process.

  8. Internal microstructure observation of enhanced grain-boundary sliding at room temperature in AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ando, D., E-mail: daisuke.ando.c4@tohoku.ac.jp; Sutou, Y.; Koike, J.

    2016-06-01

    The origin of grain boundary sliding (GBS) is known to be slip-induced due to plastic incompatibility near the grain boundary at room temperature. In this study, the relationship between GBS and crystal orientation was investigated in AZ31 Mg alloy rolled sheets at room temperature. The GBS tendency was determined as related to basal dislocation slip where the GBS boundaries were generally located between the grains with respectively high and low or high and high Schmid factors for basal slip. The results indicate that GBS is attributed to the plastic incompatibility caused by anisotropic basal and prismatic slip. Furthermore, GBS was located in regions with localized deformation near grain boundaries. Cross-sectional focused ion beam/transmission electron microscopy (FIB/TEM) observations of these regions revealed seriately arranged subgrains adjacent to a grain boundary. Therefore, we propose that RT-GBS in AZ31 can be caused by localized crystal rotation due to dynamic recover and recrystallization by stress concentration near the grain boundary but not ordinary GBS.

  9. Optimization of process factors for self-healing vanadium-based conversion coating on AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kun; Liu, Junyao [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Lei, Ting, E-mail: tlei@mail.csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Xiao, Tao [2nd Xiangya Hospital, Central South University, Changsha 410011 (China)

    2015-10-30

    Highlights: • The optimum operating conditions were determined by an orthogonal experiment. • The coating is composed of oxides and hydroxides of V{sup 5+}, V{sup 4+} and Mg(OH){sub 2}. • The self-healing performance was investigated by cross-cut immersion test. • The vanadia conversion coating provided active corrosion protection to AZ31 alloy. - Abstract: A self-healing vanadium-based conversion coating was prepared on AZ31 magnesium alloy. The optimum operating conditions including vanadia solution concentration, pH and treating temperature for obtaining the best corrosion protective vanadia coatings and improved localized corrosion resistance to the magnesium substrate were determined by an orthogonal experiment design. Surface morphology and composition of the resultant conversion coatings were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The self-healing behavior of the coating was investigated by cross-cut immersion test and electrochemical impedance spectroscopy (EIS) measurements in 3.5% NaCl solution.

  10. Effect of Ultrasonic Treatment in the Static and Dynamic Mechanical Behavior of AZ91D Mg Alloy

    Directory of Open Access Journals (Sweden)

    Helder Puga

    2015-11-01

    Full Text Available The present study evaluates the effect of high-intensity ultrasound (US in the static and dynamic mechanical behavior of AZ91D by microstructural modification. The characterization of samples revealed that US treatment promoted the refinement of dendrite cell size, reduced the thickness, and changed the β-Mg17Al12 intermetallic phase to a globular shape, promoted its uniform distribution along the grain boundaries and reduced the level of porosity. In addition to microstructure refinement, US treatment improved the alloy mechanical properties, namely the ultimate tensile strength (40.7% and extension (150% by comparison with values obtained for castings produced without US vibration. Moreover, it is suggested that the internal friction, enhanced by the reduction of grain size, is compensated by the homogenization of the secondary phase and reduction of porosity. It seems that by the use of US treatment, it is possible to enhance static mechanical properties without compromising the damping properties in AZ91D alloys.

  11. Use of Friction Stir Processing for Improving Heat-Affected Zone Liquation Cracking Resistance of a Cast Magnesium Alloy AZ91D

    Science.gov (United States)

    Karthik, G. M.; Janaki Ram, G. D.; Kottada, Ravi Sankar

    2017-10-01

    In this work, a cast magnesium alloy AZ91D was friction stir processed. Detailed microstructural studies and Gleeble hot ductility tests were conducted on the as-cast and the FSPed samples to comparatively assess their heat-affected zone liquation cracking behavior. The results show that the use of FSP as a pretreatment to fusion welding can strikingly improve the heat-affected zone liquation cracking resistance of alloy AZ91D by reducing the amount and size of the low-melting eutectic β (Mg17Al12) as well as by refining the matrix grain size.

  12. Validación de metodología para determinación de azúcares reductores totales en vinos fermentados

    OpenAIRE

    Canseco, Alejandra; Aráoz Martínez, Juan; Gusils Leon, Carlos Horacio; Zossi, Silvia

    2017-01-01

    Es importante disponer de un método para cuantificar bajas concentraciones de azúcares reductores totales al final del proceso de fermentación alcohólica. El objetivo de este estudio fue adaptar y validar la metodología basada en el uso del ácido 3,5-dinitrosalicílico para la determinación de azúcares reductores totales en vinos fermentados. Se determinaron los límites de detección y cuantificación, linealidad, sesgo e incertidumbre expandida relativa. Los resultados mostraron que este método...

  13. A New Factor in American Destiny: Visions of Porfirio Díaz and the Politics of “Logical Paternalism”

    OpenAIRE

    Jason Ruiz

    2011-01-01

    This essay interprets American representations of dictator Porfirio Díaz in relation to the “economic conquest” of Mexico that took place during his long rule (1876–1911, a period known as the “Porfiriato,” in which Americans invested more than $1 billion). No single person inspired as much attention from travelers, reporters, and photographers during the late nineteenth and early twentieth centuries as Díaz, and their visions of the President helped to shape perceptions of Mexico as a desira...

  14. A Conflict into the University and the Origins of the Antilullian Repression in the Seminar of Majorca by Bishop Juan Díaz de la Guerra

    Directory of Open Access Journals (Sweden)

    Francisco José GARCÍA PÉREZ

    2015-12-01

    Full Text Available This article, by commenting some umpublished sources, tries to study the origins of the Anti-Lullian repression in the Conciliar Seminar of Majorca by Bishop Juan Díaz de la Guerra (1772-1777. The repression started in a conflict between a student that opposed to the cult and doctrine of Ramon Llull and others that believed it. After some violent facts, started a rough repression of the Bishop Díaz de la Guerra against the traditional devotion to Ramon Llull in the Seminar of Majorca

  15. Valores percentilares del contenido de azúcar, grasas y sodio en alimentos industrializados según etiquetado expendidos en Lima

    OpenAIRE

    Miranda Cipriano, Oscar Roy; Gómez Guizado, Guillermo Luis; Munares García, Oscar Fausto; Aquino Vivanco, Oscar Samuel

    2014-01-01

    Objetivo. Determinar los percentiles del contenido de azúcar, sodio y grasas saturadas descritas en los alimentos industrializados según etiquetado por categorías de alimentos industrializados en lugares de expendio de Lima. Metodología. Se trató de un estudio prospectivo con 565 registros de alimentos, a los cuales se les observó los contenidos de azúcar, grasas saturadas y sodio que presentaban en su información nutricional, para luego obtener medidas decilares de los productos en general y...

  16. Propiedades mecánicas de la aleación AZ31 procesada por una ruta eco-sostenible

    Directory of Open Access Journals (Sweden)

    D’Errico, F.

    2013-12-01

    Full Text Available Recently it has been proved that molding of defect-free components of various commercial alloys of magnesium can be carried out succesfully when small amounts of CaO are added to the melt, making unnecessary the use of SF6 coverage. In the case of AZ alloys, this process also remarkably improves their mechanical properties not only by the greater cleaning of alloys but also by the formation of CaAl2 phase. This work, part of the Green project Metallurgy (http://www.green-metallurgy.eu funded by the European Union (LIFE+2009, studies the influence of different CaO additions on the microstructure and mechanical properties of AZ31 Eco-Mg alloy. The alloy was processed by a conventional route involving extrusion of as-cast rods as well as by a powder metallurgy route (PM using chips as starting material. The objective was to analyze the viability of recycling machining chips to manufacture components for the automobile industry and transportation in general, because of its low cost and environmental impact. It has been demostrated that alloys processed from chips exhibit the highest tensile stress values, close to 320 MPa.Recientemente se ha demostrado la posibilidad de fabricar por moldeo, componentes libres de defectos de diferentes aleaciones comerciales de magnesio, añadiendo CaO al caldo, sin emplear SF6. En el caso de las aleaciones AZ este proceso, además, mejora notablemente las propiedades mecánicas, no sólo por la mayor limpieza de las aleaciones sino también por la presencia de la fase CaAl2 que se forma por la incorporación de calcio al caldo. Este trabajo, enmarcado dentro del proyecto Green Metallurgy (http://www.green-metallurgy.eu financiado por la Unión Europea (Programa LIFE+2009, estudia la influencia de diferentes adiciones de CaO en la microestructura y propiedades mecánicas de la aleación Eco-Mg AZ31. El estudio se lleva a cabo en aleaciones AZ31 con 0,5, 1 y 1,5% CaO procesadas por dos rutas diferentes, aleaciones

  17. Reação da laranjeira azêda à tristeza Reaction of the sour orange plant to tristeza

    Directory of Open Access Journals (Sweden)

    A. S. Costa

    1954-01-01

    Full Text Available Mudinhas novas de laranjeira azêda podem ser infetadas com o vírus da tristeza por meio do afídio vetor da moléstia ou mais fàcilmente por enxertia. Plantas adultas são muitos resistentes, quase imunes. A recuperação do vírus da tristeza de plantas de laranja azeda infetadas é efetuada com facilidade por meio de enxertia e com muita dificuldade por meio do vetor. Os sintomas comumente apresentados por mudinhas de laranja azêda afetadas, consistem em amarelecimento das fôlhas novas, paralisação no crescimento e eventual queda das fôlhas amareladas. Em caso de infecção com estirpes fracas do vírus, os sintomas são menos evidentes e comumente há recuperação. As fôlhas formadas após recuperação, muitas vêzes apresentam palidez de pequenas extensões das nervuras. Os tecidos do floema da laranjeira azêda, abaixo do enxêrto de laranjeira doce infetada, mostram degeneração. Êstes sintomas têm sido utilizados para distinguir a tristeza de outras moléstias que causam declínio da planta. Sintomas de depressões no lenho ("pitting" raramente se manifestam em laranjeira azêda. Não se conhece presentemente nenhuma variedade de laranja azêda tolerante à tristeza, não se podendo, portanto, utilizar êsse cavalo para copas nas quais o vírus da tristeza se multiplica e atinge concentrações elevadas. Entretanto, a laranjeira azeda ainda pode ser usada como cavalo para alguns limões dos tipos Eureka e Siciliano e para a própria laranjeira azêda, em áreas invadidas pela moléstia. Há possibilidade de que o cavalo de azêda possa vir a ser novamente empregado para variedades que usualmente perecem quando nela enxertadas, lançando-se mão de medidas auxiliares como a inoculação prévia da copa com uma estirpe fraca do vírus, pela utilização do tipo de copa com união múltipla, etc. Borbulhas de plantas de laranja azêda afetadas pela tristeza nem sempre encerram o vírus. Borbulhas de plantas afetadas ou de

  18. Arsenic Removal from Drinking Water by Adsorptive Media - U.S. EPA Demonstration Project at Covered Wells in Tohono O’odham Nation, AZ - Final Performance Evaluation Report

    Science.gov (United States)

    This report documents the activities performed and the results obtained from the arsenic removal treatment technology demonstration project at Covered Wells in Tohono O’odham Nation, AZ. The main objective of the project was to evaluate the effectiveness of AdEdge Technologies’ ...

  19. Azúcares adicionados a los alimentos: efectos en la salud y regulación mundial. Revisión de la literatura

    Directory of Open Access Journals (Sweden)

    Claudia Constanza Cabezas Zabala

    2016-04-01

    Al comparar los efectos del consumo de azúcar con los producidos por el alcohol, se plantea que las acciones de control deben ser similares a las del tabaco y el alcohol, en las que se intervienen la promoción, la publicidad, el precio y los lugares de distribución.

  20. Az árak észlelése és értékelése(Perception and Evaluation of Prices)

    OpenAIRE

    Rekettye, Gábor

    2012-01-01

    A 2008-ban kezdődött gazdasági válság a korábbiaknál is fontosabbá tette az árakat a vásárlók számára. Azt eddig is mindenki tudta, hogy az árak alapvetően befolyásolják a fogyasztók vásárlási döntését. Arra a kérdésre azonban, hogy miképpen, már nem mindig tudunk pontos választ adni. A közgazdaságtan szerint az árak csökkenése növeli a fogyasztók vásárlási hajlandóságát és fordítva, az árak emelkedése kisebbíti azt. A valóság azonban nem mindig írható le közgazdaságtani fogalmakk...

  1. Comportamiento frente a la corrosión y biocompatibilidad in vitro/in vivo de la aleación AZ31 modificada superficialmente

    Directory of Open Access Journals (Sweden)

    Escudero, M. L.

    2011-06-01

    Full Text Available The present work evaluates the corrosion behaviour and the in vitro/in vivo biocompatibility of the AZ31 magnesium alloy, which fulfills the mechanical requirements of bone. The corrosion kinetic of as-received AZ31 alloy was not compatible with the cell growth. To improve its performance, the AZ31 alloy was surface modified by a chemical conversion treatment in hydrofluoric acid. The magnesium fluoride layer generated by the surface treatment of AZ31 alloy enhances its corrosion behaviour, allowing the in vitro growth of osteoblastic cells over the surface and the in vivo formation of a highly compact layer of new bone tissue. These results lead to consider the magnesium fluoride coating as necessary for potential use of the AZ31 alloy as biodegradable and absorbable implant for bone repair.En el presente trabajo se ha estudiado el comportamiento frente a la corrosión y la biocompatibilidad in vitro/in vivo de la aleación de magnesio AZ31, cuyas propiedades mecánicas son superiores a los requisitos mecánicos del hueso. La aleación en estado de recepción ha mostrado una cinética de corrosión no compatible con el crecimiento celular. Para mejorar su comportamiento, el material ha sido modificado superficialmente mediante tratamiento de conversión química en ácido fluorhídrico. La capa de fluoruro de magnesio generada tras este tratamiento mejora el comportamiento del material frente a la corrosión, permitiendo el crecimiento in vitro de células osteoblásticas sobre su superficie y la formación in vivo de una capa de nuevo tejido óseo muy compacta. Estos resultados permiten concluir que el recubrimiento de fluoruro de magnesio es necesario para que el material AZ31 pueda ser potencialmente aplicado como implante biodegradable y reabsorbible en reparaciones óseas.

  2. Corrosion behavior of AZ91 magnesium alloy treated by plasma immersion ion implantation and deposition in artificial physiological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Liu Chenglong [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Xin Yunchang [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Tsinghua University, Shenzhen Graduate School, Shenzhen 518055 (China); Tian Xiubo [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); State Key Laboratory of Welding Production Technology, School of Materials Science and Engineering, Harbin Institute of Technology, 15001 (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)], E-mail: paul.chu@cityu.edu.hk

    2007-12-03

    Due to the good biocompatibility and tensile yield strength, magnesium alloys are promising in degradable prosthetic implants. The objective of this study is to investigate the corrosion behavior of surgical AZ91 magnesium alloy treated by aluminum, zirconium, and titanium plasma immersion ion implantation and deposition (PIII and D) at 10 kV in artificial physiological fluids. The surface layers show a characteristic intermixed layer and the outer surface are mainly composed of aluminum, zirconium or titanium oxide with a lesser amount of magnesium oxide. Comparing the three sets of samples, aluminum PIII and D significantly shifts the open circuit potential (OCP) to a more positive potential and improves the corrosion resistance at OCP.

  3. The zeros of az2J″ν(z+bzJ′ν(z+cJν(z as functions of order

    Directory of Open Access Journals (Sweden)

    A. McD. Mercer

    1992-01-01

    Full Text Available If j″νk denotes the kth positive zero of the Bessel function J″ν(x, it has been shown recently by Lorch and Szego [2] that j″ν1 increases with ν in ν>0 and that (with k fixed in 2,3,… j″νk increases in 00. The present paper, by using a different kind of analysis, re-obtains these conclusions as a special case of a more general result concerning the positive zeros of the function az2J″ν(z+bzJ′ν(z+cJν(z. Here, the constants a, b and c are subject to certain mild restrictions.

  4. Evolution processes of the corrosion behavior and structural characteristics of plasma electrolytic oxidation coatings on AZ31 magnesium alloy

    Science.gov (United States)

    Chen, Dong; Wang, Ruiqiang; Huang, Zhiquan; Wu, Yekang; Zhang, Yi; Wu, Guorui; Li, Dalong; Guo, Changhong; Jiang, Guirong; Yu, Shengxue; Shen, Dejiu; Nash, Philip

    2018-03-01

    Evolution processes of the corrosion behavior and structural characteristics of the plasma electrolytic oxidation (PEO) coated AZ31 magnesium alloy were investigated by using scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), potentio-dynamic polarization curves and electrochemical impedance spectroscopy (EIS) measurements. Detached coating samples were fabricated by an electrochemical method and more details of the internal micro-structure of coatings were clearly observed on the fractured cross-section morphologies of the samples compared to general polished cross-section morphologies. Evolution mechanisms of the coating corrosion behavior in relation to the evolution of micro-structural characteristics were discussed in detail.

  5. The Influence of Deformation Mechanisms on Rupture of AZ31B Magnesium Alloy Sheet at Elevated Temperatures

    Science.gov (United States)

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

    Gas-pressure bulge tests were conducted on Mg alloy AZ31B wrought sheet until rupture at temperatures from 250 to 450°C. The rupture orientation was observed to change with forming pressure, which controls the forming strain rate, at 350 to 450°C. This phenomenon is a result of associated changes in the mechanisms of plastic deformation. At slow strain rates (≤ 3 × 10-2 s-1), cavity interlinkage associated with grain boundary sliding (GBS) creep induced rupture along the sheet rolling direction (RD). At fast strain rates (≥ 3 × 10-2 s-1), flow localization (necking) associated with dislocation-climb-controlled (DC) creep induced rupture along the long-transverse direction (LTD), a result of mild planar anisotropy. Biaxial bulge specimens tested at 250 to 300°C ruptured explosively, hence preventing any further analysis.

  6. Effects of carbon dioxide plasma immersion ion implantation on the electrochemical properties of AZ31 magnesium alloy in physiological environment

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ruizhen; Yang, Xiongbo; Zhang, Xuming; Wang, Mei; Li, Penghui; Zhao, Ying; Wu, Guosong; Chu, Paul K., E-mail: paul.chu@cityu.edu.hk

    2013-12-01

    Plasma immersion ion implantation (PIII) is conducted to improve the intrinsically poor corrosion properties of biodegradable AZ31 magnesium alloy in the physiological environment. Carbon dioxide is implanted into the samples and X-ray photoelectron spectroscopy and scanning electron microscopy are used to characterize the materials. The corrosion properties are systematically studied by potentiodynamic polarization tests in two simulated physiological environments, namely simulated body fluids and cell culture medium. The plasma-implanted materials exhibit a lower initial corrosion rate. Being a gaseous ion PIII technique, conformal ion implantation into an object with a complex shape such as an orthopedic implant can be easily accomplished and CO{sub 2} PIII is a potential method to improve the biological properties of magnesium and its alloys in clinical applications.

  7. Corrosion Behavior of PEO Coatings Formed on AZ31 Alloy in Phosphate-Based Electrolytes with Calcium Acetate Additive

    Science.gov (United States)

    Ziyaei, E.; Atapour, M.; Edris, H.; Hakimizad, A.

    2017-07-01

    The PEO coating started on magnesium AZ31 using a unipolar DC power source. The coating was generated in the electrolyte based on Na3PO4·12H2O and KOH with calcium acetate as additive. The x-ray diffraction method showed some phases containing calcium and phosphate, which was created in the presence of additive. Also, the EDS tests of the sample's surfaces proved the existence of calcium on the surface. Based on the electrochemical tests results, the most corrosion resistance belongs to the sample with calcium acetate additive. In fact, the results of the EIS tests showed the coating with calcium acetate has the highest resistance but the lowest capacitance. However, this state belongs to the surface morphology, the lower porosity, and surface chemical composition.

  8. Stress Corrosion Cracking Behavior of Fine-Grained AZ61 Magnesium Alloys Processed by Equal-Channel Angular Pressing

    Directory of Open Access Journals (Sweden)

    Qiuyuan Xie

    2017-09-01

    Full Text Available The effect of equal-channel angular pressing (ECAP on stress corrosion cracking (SCC behavior of a cast AZ61 Mg alloy was investigated in distilled water (DW using the slow strain rate tensile test (SSRT at a strain rate of 1 × 10−6 s−1. The fine-grained alloy after ECAP showed a greater SCC susceptibility but a higher ultimate tensile strength, compared with the as-cast counterpart. The results were attributed to refined grains, high-density dislocations and increased proportion of high-angle grain boundaries induced by severe plastic deformation, as well as isolated fine β-phase particles transiting from net-like β-phase.

  9. Surface morphology, microstructure and properties of as-cast AZ31 magnesium alloy irradiated by high intensity pulsed ion beams

    Science.gov (United States)

    Ma, Xuesong; Zhang, Gang; Wang, Guotian; Zhu, Guoliang; Zhou, Wei; Wang, Jun; Sun, Baode

    2014-08-01

    High intensity pulsed ion beam (HIPIB) irradiation was performed as surface modification to improve the properties of as-cast AZ31 magnesium (Mg) alloys. The surface morphology and microstructure of the irradiated Mg alloys were characterized and their microhardness, wear resistance and corrosion resistance before and after HIPIB irradiation were measured. The results show that the formation of crater on the surface was attributed to the particles impacted from the irradiated cathode material. HIPIB irradiation resulted in more vacancy defects on the surface of the material. Moreover, new dislocations were generated by the reaction between vacancies, and the dislocation configuration was also changed. These variations caused by the HIPIB are beneficial for improving the material properties. After 10 shots of irradiation, the average microhardness increased by 27.1% but the wear rate decreased by 38.5%. The corrosion rate was reduced by 24.8% according to the salt spray corrosion experiment.

  10. Stress corrosion cracking of high-strength AZ31 processed by high-ratio differential speed rolling

    Directory of Open Access Journals (Sweden)

    Zhiming Shi

    2015-12-01

    Full Text Available Stress corrosion cracking (SCC in distilled water was studied for AZ31, processed by differential-speed-rolling to different strengths, using Linear Increasing Stress Tests (LISTs. The stress corrosion crack velocity was 5.0 ± 2.5 × 10−9 m s−1, independent of applied stress rate and independent of material strength. SCC susceptibility was greater at lower applied stress rates manifest most importantly as a lower threshold stress for stress corrosion crack initiation. SCC susceptibility could be characterised by the ratio of threshold stress to yield stress, which was dependent on processing details and was as low as 0.3.

  11. On the System of Diophantine Equations x2-6y2=-5 and x=az2-b

    Directory of Open Access Journals (Sweden)

    Silan Zhang

    2014-01-01

    Full Text Available Mignotte and Pethö used the Siegel-Baker method to find all the integral solutions (x,y,z of the system of Diophantine equations x2-6y2=-5 and x=2z2-1. In this paper, we extend this result and put forward a generalized method which can completely solve the family of systems of Diophantine equations x2-6y2=-5 and x=az2-b for each pair of integral parameters a,b. The proof utilizes algebraic number theory and p-adic analysis which successfully avoid discussing the class number and factoring the ideals.

  12. Influence of tool material and rotational speed on mechanical properties of friction stir welded AZ31B magnesium alloy

    Directory of Open Access Journals (Sweden)

    Ugender Singarapu

    2015-12-01

    Full Text Available In this investigation, the effect of friction stir welding (FSW parameters such as tool material rotational speed, and welding speed on the mechanical properties of tensile strength, hardness and impact energy of magnesium alloy AZ31B was studied. The experiments were carried out as per Taguchi parametric design concepts and an L9 orthogonal array was used to study the influence of various combinations of process parameters. Statistical optimization technique, ANOVA, was used to determine the optimum levels and to find the significance of each process parameter. The results indicate that rotational speed (RS and traverse speed (TS are the most significant factors, followed by tool material (TM, in deciding the mechanical properties of friction stir processed magnesium alloy. In addition, mathematical models were developed to establish relationship between different process variables and mechanical properties.

  13. Effect of solution concentration on sealing treatment of Mg-Al hydrotalcite film on AZ91D Mg alloy

    Directory of Open Access Journals (Sweden)

    Qiangsheng Dong

    2017-09-01

    Full Text Available Cerium-based sealing treatment was developed for Mg-Al hydrotalcite film on AZ91D Mg alloy, and the influence of cerium salt solution was investigated to modify the surface integrity and corrosion resistance. Scanning electron microscope (SEM and X-ray diffraction (XRD measurements were carried out to analyze the surface morphology and phase composition. The corrosion resistance of Mg-Al hydrotalcite film after sealing treatment was evaluated by the polarization curve and electrochemical impedance spectroscopy (EIS tests. The results showed that lower concentration of Ce-containing solution was beneficial to seal the micro-cracks on Mg-Al hydrotalcite film, and improve the surface integrity and corrosion resistance; higher concentration of Ce-containing solution could seal fewer micro-cracks, and the corrosion resistance was decreased owing to the disintegration of Mg-Al hydrotalcite film.

  14. Homogenization and texture development in rapidly solidified AZ91E consolidated by Shear Assisted Processing and Extrusion (ShAPE)

    Energy Technology Data Exchange (ETDEWEB)

    Overman, N. R.; Whalen, S. A.; Bowden, M. E.; Olszta, M. J.; Kruska, K.; Clark, T.; Stevens, E. L.; Darsell, J. T.; Joshi, V. V.; Jiang, X.; Mattlin, K. F.; Mathaudhu, S. N.

    2017-07-01

    Shear Assisted Processing and Extrusion (ShAPE) -a novel processing route that combines high shear and extrusion conditions- was evaluated as a processing method to densify melt spun magnesium alloy (AZ91E) flake materials. This study illustrates the microstructural regimes and transitions in crystallographic texture that occur as a result of applying simultaneous linear and rotational shear during extrusion. Characterization of the flake precursor and extruded tube was performed using scanning and transmission electron microscopy, x-ray diffraction and microindentation techniques. Results show a unique transition in the orientation of basal texture development. Despite the high temperatures involved during processing, uniform grain refinement and material homogenization are observed. These results forecast the ability to implement the ShAPE processing approach for a broader range of materials with novel microstructures and high performance.

  15. La Caña de Azúcar y sus Derivados en la Huasteca San Luís Potosí México

    Directory of Open Access Journals (Sweden)

    Noé Aguilar Rivera

    2011-08-01

    Full Text Available La caña de azúcar es el principal cultivo de México, su cosecha se lleva a cabo en 665,000 ha que ocupan a 2.5 millones de personas. Existen 57 ingenios azucareros localizados en 15 estados de la republica. La industria ha cambiado dramáticamente desde la introducción de la caña de azúcar hace 486 años (año 1523 y su situación es reflejo de su metamorfosis y de intereses económicos y políticos. Fueron los españoles quienes introdujeron la caña de azúcar y tomaron así ventajas de las condiciones favorables que México ofrecía para el cultivo y la comercialización de los productos de derivados de la caña de azúcar (melazas, azúcar, panela o piloncillo y aguardiente. Grandes plantaciones fueron establecidas en diversas áreas como la Huasteca Potosina (San Luis Potosí. Esas plantaciones modificaron no solo las condiciones de vida, además la constitución de cada una de esas sociedades. El cambio fue dramático debido a la gran cantidad de indígenas nativos y al interés de los españoles hacia otras mercancías como los minerales y otros cultivos. En este trabajo se presentan algunos aspectos de la evolución y las estrategias para el desarrollo de la industria azucarera en la Huasteca Potosina San Luis Potosí durante el Virreinato de Nueva España.

  16. Study on typical hole defects in AZ91D magnesium alloy prepared by low pressure lost foam casting

    Directory of Open Access Journals (Sweden)

    Li Jiqiang

    2013-07-01

    Full Text Available The hole defects can easily occur in magnesium alloy castings that are prepared by low pressure lost foam casting (LP-LFC process when the process parameters such as vacuum, pouring temperature and filling velocity are not properly selected. In this study, the forming mechanism of the hole defects in AZ91D magnesium castings by LP-LFC process was investigated. The shape, location and surface appearance of the hole defects were observed using optical microscopy and scanning electron microscopy, and the chemical composition on the surface of the holes was analyzed using energy spectrometer. The result indicates that there are two types of hole defects, i.e., the pyrolysis products related hole defects, including concentrative hole and blow hole defects, and slag related hole defects. The concentrative hole and the blow-hole defects were formed either by the liquid-EPS degradation products entrapped in the molten metal under the condition that the pouring temperature is equal to or lower than 730 ℃, or by the hindered transport of EPS pyrolysis products. Some irregular shape hole defects were caused by slag or by coating slough entrapment when the pouring temperature is equal to 750 ℃ and the filling velocity is equal to or greater than 100 mm·s-1. To reduce or eliminate the hole defects, the vacuum and filling velocity must be properly chosen to ensure that the metal front profile exhibits convex shape and in laminar current state, and the pouring temperature should be just high enough to ensure that the molten melt has adequate heat energy to complete the foam pyrolysis and to fully occupy the mould. For AZ91D magnesium castings in this study, the parameters should be 730 ℃ pouring temperature, 0.02-0.03 MPa vacuum and 80 mm·s-1 filling velocity.

  17. Análisis métrico de las comunicaciones de la revista Centro Azúcar

    Directory of Open Access Journals (Sweden)

    Luis Ernesto Paz Enrique

    2016-03-01

    Full Text Available Las publicaciones científicas en línea generalmente se apoyan en los análisis métricos, favoreciendo la descripción de las revistas para su mejora continua. La revista Centro Azúcar se encuentra hace varios años en evaluación por bases de datos de prestigio internacional. La publicación carece de un estudio métrico que refleje la calidad de la publicación en consonancia a los indicadores establecidos por las fuentes de indización. Se plantean como objetivos del estudio examinar la producción científica de la revista Centro Azúcar desde el 2011 hasta el 2015, examinar las referencias contenidas en el período mencionado e identificar los índices de endogamia editorial presentes en la productividad y las referencias de los artículos publicados por la revista. Para la obtención de resultados se emplean métodos en los niveles teórico y empírico, destacándose el método bibliométrico. Se identifican varios aspectos que atentan contra la calidad de la publicación. Se aborda de forma novedosa el comportamiento de la endogamia editorial en las referencias. Se emiten valoraciones y se establecen aspectos a considerar por la publicación para que sea indizada en bases de datos de prestigio internacional.

  18. Processing, microstructure and mechanical properties of bimodal size SiCp reinforced AZ31B magnesium matrix composites

    Directory of Open Access Journals (Sweden)

    M.J. Shen

    2015-06-01

    Full Text Available The bimodal size SiC particulates (SiCp reinforced magnesium matrix composites with different ratios of micron SiCp and nano SiCp (M-SiCp:N-SiCp = 14.5:0.5, 14:1, and 13.5:1.5 were prepared by semisolid stirring assisted ultrasonic vibration method. The AZ31B alloy and all as-cast SiCp/AZ31B composites were extruded at 350 °C with the ratio of 12:1. Microstructural characterization of the extruded M14 + N1 (M-SiCp:N-SiCp = 14:1 composite revealed the uniform distribution of bimodal size SiCp and significant grain refinement. Optical Microscopy(OM observation showed that, compared with the M14.5 + N0.5 (M-SiCp:N-SiCp = 14.5:0.5 composite, there are more recrystallized grains in M14 + N1 (M-SiCp:N-SiCp = 14:1 and M13.5 + N1.5 (M-SiCp:N-SiCp = 13.5:1.5 composites, but in comparison to the M13.5 + N1.5 composite, the average grain size of the M14 + N1 composite is slightly decreased. The evaluation of mechanical properties indicated that the yield strength and ultimate tensile strength of the M14 + N1 composite were obviously increased compared with other composites.

  19. A combined coating strategy based on atomic layer deposition for enhancement of corrosion resistance of AZ31 magnesium alloy

    Science.gov (United States)

    Liu, Xiangmei; Yang, Qiuyue; Li, Zhaoyang; Yuan, Wei; Zheng, Yufeng; Cui, Zhenduo; Yang, Xianjin; Yeung, Kelvin W. K.; Wu, Shuilin

    2018-03-01

    Rapid corrosion restricts the wide application of Mg and Mg-based alloys. In this work, a combined surface strategy was employed to modify the surface of AZ31 Mg Alloy. An atomic layer deposition (ALD) technique was utilized to prepare ZrO2 nanofilm on Mg substrate. During this course, the film thickness could be precisely controlled by adjusting the ALD cycles with a deposition rate of 0.117 nm/cycle. The subsequent PLGA grafting on ZrO2 nanofilm was carried out by a spin-coating process to further enhance the corrosion resistance. The nanoscratch tests showed that this hybrid coating had good bonding strength with substrate and similar Young's modulus to natural bone. In vitro corrosion tests demonstrated that a thicker ZrO2 nanofilm on the surface could reduce the corrosion rate of Mg substrate when compared to a thinner coating. When increasing ZrO2 deposition cycles from 25 to 100, the corrosion resistance could be significantly increased by two or three orders of magnitude. Hydrogen evolution tests revealed the synergetic effects of both galvanic corrosion and local acidic action could accelerate the corrosion of the AZ31 modified with the PLGA/ZrO2 coating once the ZrO2 nanofilm was damaged. Therefore, by changing the ALD cycles, the corrosion resistance of both ZrO2 thin film and ZrO2/PLGA hybrid coatings can be adjusted. This work provides an effective combined surface strategy that can be employed to adjust the corrosion resistance of Mg-based alloys for biomedical applications.

  20. Epocas de siembra de girasol intercalado en caña de azúcar

    Directory of Open Access Journals (Sweden)

    Domínguez Pablo

    1989-12-01

    Full Text Available Con el objeto de determinar la época más oportuna de siembra de girasol intercalado de caña se estableció un experimento en el Ingenio Providencia en el Cerrito, (Colombia, utilizando los híbridos de girasol DO 664 Y DO 855, en seis épocas soca (10, 15,20,25,30 y 35 días después del corte de caña CP 57603. La caña estaba sembrada entre surcos a 1.5 m y se le intercaló un surco de girasol en una población aproximada de 27 000 plantas/ha. El experimento se diseñó en bloques al azar y se arregló en parcelas divididas. En girasol se logró una producción promedia máxima de 1085 kg/ha cuando se sembró a los 10 días después del corte de la caña y decrecio el rendimiento significativamente a medida que se sembró más tarde. La siembra más aconsejable ocurrió dentro de los 10 a 25 días después de cortada la caña. El tamaño de la semilla se afectó notablemente a medida que se sembró más tarde, los porcentajes de cáscara y almendra no sufrieron variación. El diámetro del capítulo, la altura y diámetro del tallo fueron mayores en las siembras más cercanas al corte de la caña. Después de cosechado el girasol se obtuvieron 142 t/ha/ caña y 11.9 t de azúcar/ha, demostrando una recuperación total de la gramínea, lo cual se reflejó en el poco efecto que tuvo el girasol en la población, altura y diámetro final del tallo de la caña.An experiment to evaluate the most convenient planting date of sunflower intercropped in sugarcane ratoons, was carried out at the sugar mill Providencia, located at the Cerrito county (Colombia. The research included two sunflower hybrids (DO 855 and DO 664 and the sugar variety CP 57603 in six dates after of harvesting of sugarcane (10, 15, 20,25,30 and 35 days. Between the distance of the rows of sugarcane (1.50 m an intercropped line of sunflower was planted using 4 plant per meter in a density population of 27000 plants/ha. The plot was formed by 10 rows of sunflower with 10 m long. A

  1. Cálculo de la huella de carbono en los procesos de preparación de suelo para un cultivo de caña de azúcar del Valle del Cauca. [recurso electrónico

    OpenAIRE

    Lubo Cetina, Claudia Marcela

    2014-01-01

    El proyecto de investigación del que se hace entrega, presenta el cálculo, de forma teórica y experimental, de la huella de carbono del proceso de preparación de suelo para un cultivo tipo soca de caña de azúcar de manejo comercial, un cultivo tipo soca de caña de azúcar de mano limpio y un cultivo tipo plantilla de caña de azúcar de manejo limpio, de un ingenio del Valle del Cauca

  2. (Sub)millimetre interferometric imaging of a sample of COSMOS/AzTEC submillimetre galaxies. III. Environments

    Science.gov (United States)

    Smolčić, V.; Miettinen, O.; Tomičić, N.; Zamorani, G.; Finoguenov, A.; Lemaux, B. C.; Aravena, M.; Capak, P.; Chiang, Y.-K.; Civano, F.; Delvecchio, I.; Ilbert, O.; Jurlin, N.; Karim, A.; Laigle, C.; Le Fèvre, O.; Marchesi, S.; McCracken, H. J.; Riechers, D. A.; Salvato, M.; Schinnerer, E.; Tasca, L.; Toft, S.

    2017-01-01

    We investigate the environment of 23 submillimetre galaxies (SMGs) drawn from a signal-to-noise (S/N)-limited sample of SMGs originally discovered in the James Clerk Maxwell Telescope (JCMT)/AzTEC 1.1 mm continuum survey of a Cosmic Evolution Survey (COSMOS) subfield and then followed up with the Submillimetre Array and Plateau de Bure Interferometer at 890 μm and 1.3 mm, respectively. These SMGs already have well-defined multiwavelength counterparts and redshifts. We also analyse the environments of four COSMOS SMGs spectroscopically confirmed to lie at redshifts zspec > 4.5, and one at zspec = 2.49 resulting in a total SMG sample size of 28. We search for overdensities using the COSMOS photometric redshifts based on over 30 UV-NIR photometric measurements including the new UltraVISTA data release 2 and Spitzer/SPLASH data, and reaching an accuracy of σΔz/ (1 + z) = 0.0067 (0.0155) at z 3.5). To identify overdensities we apply the Voronoi tessellation analysis, and estimate the redshift-space overdensity estimator δg as a function of distance from the SMG and/or overdensity centre. We test and validate our approach via simulations, X-ray detected groups or clusters, and spectroscopic verifications using VUDS and zCOSMOS catalogues which show that even with photometric redshifts in the COSMOS field we can efficiently retrieve overdensities out to z ≈ 5. Our results yield that 11 out of 23 (48%) JCMT/AzTEC 1.1 mm SMGs occupy overdense environments. Considering the entire JCMT/AzTEC 1.1 mm S/N ≥ 4 sample and taking the expected fraction of spurious detections into account, this means that 35-61% of the SMGs in the S/N-limited sample occupy overdense environments. We perform an X-ray stacking analysis in the 0.5-2 keV band using a 32″ aperture and our SMG positions, and find statistically significant detections. For our z 2 subsample yields an average flux of (1.3 ± 0.5) × 10-16 erg s-1 cm-2 and a corresponding total massof M200 = 2 × 1013M⊙. Our

  3. Evolution of the Corrosion Morphology on AZ31B Tracked Electrochemically and by In Situ Microscopy in Chloride-Containing Media

    Science.gov (United States)

    Melia, M. A.; Cain, T. W.; Briglia, B. F.; Scully, J. R.; Fitz-Gerald, J. M.

    2017-11-01

    The evolution of open-circuit corrosion morphology as a function of immersion time for Mg alloy AZ31B in 0.6-M NaCl solution was investigated. Real-time optical microscopy accompanied by simultaneous electrochemical characterization was used to characterize the filiform corrosion (FFC) of AZ31B. Specifically, the behavior of propagating corrosion filaments on the metal surface was observed, and correlations among polarization resistance, filament propagation rates, open-circuit potential, and active coverage of local corrosion sites were revealed. Three distinct stages of corrosion were observed in 0.6-M NaCl. An initial passive region, during which a slow potential rise occurred (termed stage I), a second FFC region (termed stage II) with shallow penetrating, distinct filaments, and a final FFC region (termed stage III) with deeper penetrating filaments, aligned to form a linear front. The electrochemical properties of each stage are discussed, providing insights into the penetration rates and corrosion model.

  4. Porfirio Díaz y la “Gran Dieta Simbólica”: ¿La masonería mexicana bajo control?

    OpenAIRE

    Rogelio Aragón

    2015-01-01

    Las fuentes más consultadas para la historia de la masonería en México durante el período conocido como "Porfiriato" apuntan a que fue, precisamente, el presidente Porfirio Díaz el artífice de la unificación de la masonería bajo la llamada "Gran Dieta Simbólica". Sin embargo, el intercambio epistolar entre el general Díaz y Ermilio Cantón -que más bien fue monólogo epistolar de este último-, dirigente de facto de la Gran Dieta, apunta en una dirección distinta. El presente artículo contrapone...

  5. FINAL REPORT DM1200 TESTS WITH AZ 101 HLW SIMULANTS VSL-03R3800-4 REV 0 2/17/04

    Energy Technology Data Exchange (ETDEWEB)

    KRUGER AA; MATLACK KS; BARDAKCI T; D' ANGELO NA; GONG W; KOT WK; PEGG IL

    2011-12-29

    This report documents melter and off-gas performance results obtained on the DM 1200 HLW Pilot Melter during processing of simulated HLW AZ-101 feed. The principal objectives of the DM1200 melter testing were to determine the achievable glass production rates for simulated HLW AZ-101 feed; determine the effect of bubbling rate and feed solids content on production rate; characterize melter off-gas emissions; characterize the performance of the prototypical off-gas system components as well as their integrated performance; characterize the feed, glass product, and off-gas effluents; and to perform pre- and post-test inspections of system components. The test objectives (including test success criteria), along with how they were met, are outlined in a table.

  6. Heat-Transfer Coefficient and In-Cavity Pressure at the Casting-Die Interface during High-Pressure Die Casting of the Magnesium Alloy AZ91D

    Science.gov (United States)

    Hamasaiid, A.; Dour, G.; Dargusch, M. S.; Loulou, T.; Davidson, C.; Savage, G.

    2008-04-01

    The present article deals with the application of a new measurement method to determine the heat-transfer coefficient (HTC) and the heat flux density at the casting-die interface during high-pressure die casting (HPDC) and solidification of the magnesium AZ91D alloy. The main measurements during the trial included velocity and the position of the piston that delivers the metal into the die, the pressure in the die cavity and at the tip of the piston, the alloy surface temperature, and the die temperature at different depths from the surface of the die. The temperature data were analyzed using an inverse method to determine the HTC at the casting-die interface during solidification. This article examines in detail the influence of the piston velocity and in-cavity pressure on heat transfer at the casting-die interface during casting and solidification of the magnesium AZ91D alloy.

  7. Porfirio Díaz y la “Gran Dieta Simbólica”: ¿La masonería mexicana bajo control?

    Directory of Open Access Journals (Sweden)

    Rogelio Aragón

    2015-01-01

    Full Text Available Las fuentes más consultadas para la historia de la masonería en México durante el período conocido como"Porfiriato" apuntan a que fue, precisamente, el presidente Porfirio Díaz el artífice de la unificación de lamasonería bajo la llamada "Gran Dieta Simbólica". Sin embargo, el intercambio epistolar entre el generalDíaz y Ermilio Cantón -que más bien fue monólogo epistolar de este último-, dirigente de facto de la GranDieta, apunta en una dirección distinta. El presente artículo contrapone la información proporcionada por lasfuentes bibliográficas con la correspondencia del presidente.

  8. In Vitro Analysis of Electrophoretic Deposited Fluoridated Hydroxyapatite Coating on Micro-arc Oxidized AZ91 Magnesium Alloy for Biomaterials Applications

    Science.gov (United States)

    Razavi, Mehdi; Fathi, Mohammadhossein; Savabi, Omid; Vashaee, Daryoosh; Tayebi, Lobat

    2015-03-01

    Magnesium (Mg) alloys have been recently introduced as a biodegradable implant for orthopedic applications. However, their fast corrosion, low bioactivity, and mechanical integrity have limited their clinical applications. The main aim of this research was to improve such properties of the AZ91 Mg alloy through surface modifications. For this purpose, nanostructured fluoridated hydroxyapatite (FHA) was coated on AZ91 Mg alloy by micro-arc oxidation and electrophoretic deposition method. The coated alloy was characterized through scanning electron microscopy, transmission electron microscopy, X-ray diffraction, in vitro corrosion tests, mechanical tests, and cytocompatibility evaluation. The results confirmed the improvement of the corrosion resistance, in vitro bioactivity, mechanical integrity, and the cytocompatibility of the coated Mg alloy. Therefore, the nanostructured FHA coating can offer a promising way to improve the properties of the Mg alloy for orthopedic applications.

  9. The one-step electroposition of superhydrophobic surface on AZ31 magnesium alloy and its time-dependence corrosion resistance in NaCl solution

    Science.gov (United States)

    Zhong, Yuxing; Hu, Jin; Zhang, Yufen; Tang, Shawei

    2018-01-01

    A calcium myristic superhydrophobicity coating with a hierarchical micro-nanostructure was fabricated on AZ31 magnesium alloy by one-step electroposition. The effects of deposition time on the coating structure, such as morphology, thickness, wettability and phase composition of the coating were studied. The corrosion behavior of the coated samples in 3.5% NaCl solution was also investigated and the corrosion mechanism was discussed. It was found that the deposition time has a visible effect on the morphology, thickness and wettability, which distinctly affects the corrosion resistance of coatings. The corrosion resistance of the coating gradually decreases with the increase in the immersion time due to the disappearance of the air layer which exists on the coating surface. The superhydrophobic surfaces present the temporal limitations to the corrosion resistance of AZ31 magnesium alloy.

  10. Al-TiC in situ composite coating fabricated by low power pulsed laser cladding on AZ91D magnesium alloy

    Science.gov (United States)

    Yang, Liuqing; Li, Zhiyong; Zhang, Yingqiao; Wei, Shouzheng; Liu, Fuqiang

    2018-03-01

    Al + (Ti + B4C) composite coating was cladded on AZ91D magnesium alloy by a low power pulsed Nd-YAG laser. The Ti+B4C mixed powder is with the ratio of Ti: B4C = 5:1, which was then mixed with Al powder by weight fraction of 10%, 15% and 20%, respectively. Scanning electron microscopy, energy dispersive spectrometer and X-ray diffraction were used to study the microstructure, chemical composition and phase composition of the coating. Results showed that the coating had satisfied metallurgical bonding with the magnesium substrate. Al3Mg2, Al12Mg17, Al3Ti and TiC were formed by in-situ reaction. The coatings have micro-hardness of 348HV, which is about 5-6 times higher than that of AZ91D. The wear resistance and corrosion resistance of the coatings are enhanced with the addition of the mixed powder.

  11. Effect of Intensive Cooling of Alloy AZ91 with a Chromium Addition on the Microstructure and Mechanical Properties of the Casting

    Directory of Open Access Journals (Sweden)

    Rapiejko C.

    2017-12-01

    Full Text Available The work presents the results of the investigations of the effect of intensive cooling of alloy AZ91 with an addition of chromium on the microstructure and mechanical properties of the obtained casts. The experimental castings were made in ceramic moulds preliminarily heated to 180°C, into which alloy AZ91 with the addition was poured. Within the implementation of the research, a comparison was made of the microstructure and mechanical properties of the castings obtained in ceramic moulds cooled at room temperature and the ones intensively cooled in a cooling liquid. The kinetics and dynamics as well as the thermal effects recorded by the TDA method were compared. Metallographic tests were performed with the use of an optical microscope and the strength properties of the obtained castings were examined: UTS (Rm, elongation (A%, and HB hardness.

  12. Effect of Y Addition on the Semi-Solid Microstructure Evolution and the Coarsening Kinetics of SIMA AZ80 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Qi Tang

    2017-10-01

    Full Text Available Semi-solid feedstock of AZ80 magnesium alloy modified by trace rare-earth Y element (0, 0.2, 0.4, 0.8 wt. % was fabricated by strain-induced melting activation (SIMA in the form of extrusion and partial remelting. The effect of Y addition on the microstructure evolution of the extruded and isothermally heat treated alloy was observed by using an optical microscope (OM, scanning electron microscope (SEM, X-ray diffraction (XRD and quantitative analysis. The results show that the Y addition can refine the microstructure and make the β-Mg17Al12 phases agglomerate. During the subsequent isothermal treatment at 570 °C, the average solid grain size, shape factor and liquid fractions increased with the prolonged soaking time. The smaller spheroidal solid grains and larger shape factor were obtained in the semi-solid microstructure due to Y addition. The coalescence and Ostwald ripening mechanism operated the coarsening process of solid grains simultaneously. The coarsening rate constants of AZ80M1 (0.2 wt. % Y addition of 164.22 μm3 s−1 was approximately four times less than the un-modified AZ80 alloy of 689.44 μm3 s−1. In contrast, the desirable semi-solid structure featured, with fine and well globular solid grains, an appropriate liquid fraction, and shape factor was achieved in AZ80M1 alloy treated at 570 °C for 20–30 min.

  13. A New Factor in American Destiny: Visions of Porfirio Díaz and the Politics of “Logical Paternalism”

    Directory of Open Access Journals (Sweden)

    Jason Ruiz

    2011-12-01

    Full Text Available This essay interprets American representations of dictator Porfirio Díaz in relation to the “economic conquest” of Mexico that took place during his long rule (1876–1911, a period known as the “Porfiriato,” in which Americans invested more than $1 billion. No single person inspired as much attention from travelers, reporters, and photographers during the late nineteenth and early twentieth centuries as Díaz, and their visions of the President helped to shape perceptions of Mexico as a desirable field in which to expand US capitalism and influence. Travelers clamored to meet him and his sophisticated young wife, and their travelogues were rich with descriptions of such encounters. Reporters, dazzled by the rapid transformation of Mexico during his 35-year rule, described Díaz in such terms as “the Mexican Wizard” and “the maker of modern Mexico” until the very end of his regime. Photographers, working in a relatively new medium, amassed a huge body of works devoted to the dictator; even at an advanced age late in his rule, the President’s image adorned postcards and commemorative cartes-de-visite that posited him in heroic and hypermasculine terms (not unlike those of his US counterpart, Theodore Roosevelt. Ultimately, this essay argues that representations like these reflected American desires for a Mexican body politic that was amenable to economic and social transformation under the inextricable banners of “progress” and US capitalism. Prevailing images of Díaz and his family suggested that Mexico was as friendly to foreign investors as it was to foreign visitors.

  14. HLW Feed Delivery AZ101 Batch Transfer to the Private Contractor Transfer and Mixing Process Improvements [Initial Release at Rev 2

    Energy Technology Data Exchange (ETDEWEB)

    DUNCAN, G.P.

    2000-02-28

    The primary purpose of this business case is to provide Operations and Maintenance with a detailed transfer process review for the first High Level Waste (HLW) feed delivery to the Privatization Contractor (PC), AZ-101 batch transfer to PC. The Team was chartered to identify improvements that could be implemented in the field. A significant penalty can be invoked for not providing the quality, quantity, or timely delivery of HLW feed to the PC.

  15. Improving Tensile and Compressive Properties of an Extruded AZ91 Rod by the Combined Use of Torsion Deformation and Aging Treatment.

    Science.gov (United States)

    Song, Bo; Wang, Chunpeng; Guo, Ning; Pan, Hucheng; Xin, Renlong

    2017-03-10

    In this study, AZ91 magnesium alloy rods were used to investigate the effects of torsion deformation on microstructure and subsequent aging behavior. Extruded AZ91 rod has a uniform microstructure and typical fiber texture. Torsion deformation can generate a gradient microstructure on the cross-section of the rod. After torsion, from the center to the edge in the cross-section of the rod, both stored dislocations and area fraction of {10-12} twins gradually increase, and the basal pole of the texture tends to rotate in the ED direction. Direct aging usually generates coarse discontinuous precipitates and fine continuous precipitates simultaneously. Both twin structures and dislocations via torsion deformation can be effective microstructures for the nucleation of continuous precipitates during subsequent aging. Thus, aging after torsion can promote continuous precipitation and generate gradient precipitation characteristics. Both aging treatment and torsion deformation can reduce yield asymmetry, and torsion deformation enhances the aging hardening effect by promoting continuous precipitation. Therefore, combined use of torsion deformation and aging treatment can effectively enhance the yield strength and almost eliminate the yield asymmetry of the present extruded AZ91 rod. Finally, the relevant mechanisms are discussed.

  16. Effect of heat treatment and number of passes on the microstructure and mechanical properties of friction stir processed AZ91C magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dadashpour, M.; Yeşildal, R. [University of Ataturk, Erzurum (Turkmenistan); Mostafapour, A.; Rezazade, V. [University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2016-02-15

    In this paper, the effect of heat treatment and number of passes on microstructure and mechanical properties of friction stir processed AZ91C magnesium alloy samples were investigated. From six samples of as-cast AZ91C magnesium alloy, three plates were pre-heated at temperature of 375°C for 3 hours, and then were treated at temperature of 415°C for 18 hours and finally were cooled down in air. Three plates were relinquished without heat treatment. 8 mm thick as-cast AZ91C magnesium alloy plates were friction stir processed at constant traverse speed of 40 mm/min and tool rotation speed of 1250 rpm. After process, microstructural characterization of samples was analyzed using optical microscopy and tensile and Vickers hardness tests were performed. It was found that heat treated samples had finer grains, higher hardness, improved tensile strength and elongation relative to non-heat treated ones. As the number of passes increased, higher UTS and TE were achieved due to finer grains and more dissolution of β phase (Mg17Al12). The micro-hardness characteristics and tensile improvement of the friction stir processed samples depend significantly on grain size, removal of voids and porosities and dissolution of β phase in the stir zone.

  17. Effects of Heat Treatment on Grain-Boundary β-Mg17Al12 and Fracture Properties of Resistance Spot-Welded AZ80 Mg Alloy

    Science.gov (United States)

    Niknejad, Seyed Tirdad; Liu, Lei; Nguyen, Tam; Lee, Mok-Young; Esmaeili, Shahrzad; Zhou, Norman Y.

    2013-08-01

    The distribution and morphology of β-Mg17Al12 intermetallic phase in resistance spot-welded AZ80 Mg alloy were investigated by means of optical microscopy, scanning electron microscopy, and X-ray diffraction. The influence of intermetallic phase on mechanical strength was studied by tensile shear testing and fractography. The results showed that continuous networks of β-Mg17Al12 formed along grain boundaries in both the nugget and heat-affected zone of the spot-welded AZ80 Mg alloy. Those continuous grain-boundary β-Mg17Al12 networks acted as effective crack propagation paths, which had negative effects on the weld strength. Post-weld solution heat treatment effectively reduced the amount of β-Mg17Al12 and broke the grain-boundary intermetallic networks in both the nugget and heat-affected zone. This significantly increased the weld strength of AZ80 Mg alloy and changed the fracture mode from nugget pull-out in the as-welded condition to through-thickness after heat treatment.

  18. Microstructure characterization on the formation of in situ Mg{sub 2}Si and MgO reinforcements in AZ91D/Flyash composites

    Energy Technology Data Exchange (ETDEWEB)

    Huang Zhiqiu, E-mail: jmsdxhzq@163.com [Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, and College of Materials Science and Engineering, Jilin University, Changchun 130025 (China) and College of Materials Science and Engineering, Jiamusi University, Jiamusi 154007 (China); Yu Sirong, E-mail: yusirong4179@163.com [Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, and College of Materials Science and Engineering, Jilin University, Changchun 130025 (China)

    2011-01-12

    Research highlights: > The in situ composites AZ91D/Flyash by incorporating fly ash cenospheres were firstly fabricated by means of comp-casting method. > In situ Mg{sub 2}Si and MgO compounds in the composite formed from fly ash cenospheres were firstly investigated. - Abstract: 5 wt.% and 100 {mu}m in size of fly ash cenosphere particles were incorporated in AZ91D Mg alloy to fabricate in situ Mg{sub 2}Si and MgO reinforced AZ91D/Flyash composites by means of compocasting method. The in situ Mg{sub 2}Si and MgO were identified using X-ray diffraction (XRD), energy dispersive spectrometer (EDS), and thermodynamic analysis. The results show that the cenosphere particles distributed homogeneously in the matrix alloy. Moreover, most of the cenosphere particles were filled with the matrix alloy. The preliminary discussion was carried out on the growth mechanism of the in situ Mg{sub 2}Si.

  19. Influence of the β-Mg17Al12 Phase Morphology on the Corrosion Properties Of Az91hp Magnesium Alloy

    Science.gov (United States)

    Guo, Lingling; Zhang, Jumei

    2017-09-01

    The morphology of β-Mg17Al12 phase and corrosion behavior of AZ91HP magnesium alloy after spheroidizing treatment were investigated by optical microcope electrochemical and immersion tests in 3.5% NaCl at 25°C. The results show that the coarse divorced eutectic phase of AZ91HP cast magnesium alloy dissolve into Mg matrix during the isothermal process at 415°C, and the lameller β phase precipitated from magnesium solid solution as perlite-type precipitation during the slowly cooling. Next, the spheroidizing treatment at different temperatures for 20h was carried out, and the lameller β phase were spheroridizing by dissolved themselves. After spheroidizing treatment at 300°C for 20h, many small granular β phase are scattering within the magnesium matrix. The corrosion properties of AZ91HP magnesium alloy in 3.5% NaCl decreased obviously after spheroidizing treatment, the polarization measurement of the alloy can be up to -1.412V from -1.56V of the cast. The β-Mg17Al12 phase act as a corrosion barrier and hinder corrosion propagation, if the second phase is in the form of a spherical morphology.

  20. Three-Dimensional Microstructure Reconstruction and Finite Element Simulation of Gas Pores in the High-Pressure Die-Casting AZ91 Mg Alloy.

    Science.gov (United States)

    Jiang, Wei; Cao, Zhanyi; Sun, Xu; Liu, Haifeng

    2015-12-01

    High-pressure die-casting (HPDC) AZ91 tensile specimens were used to investigate characteristics of gas pores and their effects on mechanical properties of HPDC AZ91 magnesium (Mg) alloy. Combining the stereoscopic morphology of gas pores obtained from a three-dimensional (3D) reconstruction technique with the experimental data from uniaxial tensile testing, we worked on finite element simulation to find the relationship between gas pores and the mechanical properties of HPDC AZ91 Mg alloy. Results indicate that the 2D metallography images have one-sidedness. Moreover, gas pores >100 µm in the center region have a remarkable negative influence on the ultimate tensile strength (UTS) and elongation. With an increase in the size of large gas pores in the center region, the UTS and elongation of the material decreases. In addition, the distribution of gas pores in the specimens and the areal fraction of gas pores >100 µm on cross sections can also affect the UTS and elongation to some extent.

  1. A systematic study of mechanical properties, corrosion behavior and biocompatibility of AZ31B Mg alloy after ultrasonic nanocrystal surface modification.

    Science.gov (United States)

    Hou, Xiaoning; Qin, Haifeng; Gao, Hongyu; Mankoci, Steven; Zhang, Ruixia; Zhou, Xianfeng; Ren, Zhencheng; Doll, Gary L; Martini, Ashlie; Sahai, Nita; Dong, Yalin; Ye, Chang

    2017-09-01

    Magnesium alloys have tremendous potential for biomedical applications due to their good biocompatibility, osteoconductivity, and degradability, but can be limited by their poor mechanical properties and fast corrosion in the physiological environment. In this study, ultrasonic nanocrystal surface modification (UNSM), a recently developed surface processing technique that utilizes ultrasonic impacts to induce plastic strain on metal surfaces, was applied to an AZ31B magnesium (Mg) alloy. The mechanical properties, corrosion resistance, and biocompatibility of the alloy after UNSM treatment were studied systematically. Significant improvement in hardness, yield stress and wear resistance was achieved after the UNSM treatment. In addition, the corrosion behavior of UNSM-treated AZ31B was not compromised compared with the untreated samples, as demonstrated by the weight loss and released element concentrations of Mg and Al after immersion in alpha-minimum essential medium (α-MEM) for 24h. The in vitro biocompatibility of the AZ31B Mg alloys toward adipose-derived stem cells (ADSCs) before and after UNSM processing was also evaluated using a cell culture study. Comparable cell attachments were achieved between the two groups. These studies showed that UNSM could significantly improve the mechanical properties of Mg alloys without compromising their corrosion rate and biocompatibility in vitro. These findings suggest that UNSM is a promising method to treat biodegradable Mg alloys for orthopaedic applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. In vivo assessments of bioabsorbable AZ91 magnesium implants coated with nanostructured fluoridated hydroxyapatite by MAO/EPD technique for biomedical applications.

    Science.gov (United States)

    Razavi, Mehdi; Fathi, Mohammadhossein; Savabi, Omid; Vashaee, Daryoosh; Tayebi, Lobat

    2015-03-01

    Although magnesium (Mg) is a unique biodegradable metal which possesses mechanical property similar to that of the natural bone and can be an attractive material to be used as orthopedic implants, its quick corrosion rate restricts its actual clinical applications. To control its rapid degradation, we have modified the surface of magnesium implant using fluoridated hydroxyapatite (FHA: Ca10(PO4)6OH2-xFx) through the combined micro-arc oxidation (MAO) and electrophoretic deposition (EPD) techniques, which was presented in our previous paper. In this article, the biocompatibility examinations were conducted on the coated AZ91 magnesium alloy by implanting it into the greater trochanter area of rabbits. The results of the in vivo animal test revealed a significant enhancement in the biocompatibility of FHA/MAO coated implant compared to the uncoated one. By applying the FHA/MAO coating on the AZ91 implant, the amount of weight loss and magnesium ion release in blood plasma decreased. According to the histological results, the formation of the new bone increased and the inflammation decreased around the implant. In addition, the implantation of the uncoated AZ91 alloy accompanied by the release of hydrogen gas around the implant; this release was suppressed by applying the coated implant. Our study exemplifies that the surface coating of magnesium implant using a bioactive ceramic such as fluoridated hydroxyapatite may improve the biocompatibility of the implant to make it suitable as a commercialized biomedical product. Published by Elsevier B.V.

  3. Effect of Nd on the corrosion behaviour of AM50 and AZ91D magnesium alloys in 3.5 wt.% NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Arrabal, R., E-mail: raularrabal@quim.ucm.es [Departamento de Ciencia de Materiales, Facultad de Ciencias Quimicas, Universidad Complutense, 28040 Madrid (Spain); Pardo, A.; Merino, M.C.; Mohedano, M.; Casajus, P. [Departamento de Ciencia de Materiales, Facultad de Ciencias Quimicas, Universidad Complutense, 28040 Madrid (Spain); Paucar, K. [Gabinete de Corrosion, Facultad de Ingenieria Quimica y Textil, Universidad Nacional de Ingenieria, Cod. Postal 25, Lima (Peru); Garces, G. [Centro Nacional de Investigaciones Metalurgicas CSIC, Avda. Gregorio del Amo 8, 28040 Madrid (Spain)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Nd addition modified the microstructure of AM50 and AZ91D magnesium alloys. Black-Right-Pointing-Pointer Volume of {beta}-Mg{sub 17}Al{sub 12} phase was reduced and Al{sub 2}Nd/Al-Mn-Nd particles were formed. Black-Right-Pointing-Pointer Nd-containing intermetallics revealed lower potential than Al-Mn inclusions. Black-Right-Pointing-Pointer 0.7-0.8 wt.% Nd reduced the corrosion rate of AM50 and AZ91D alloys by 90%. - Abstract: The corrosion performance of AM50 and AZ91D alloys containing up to 1.5 wt.% Nd was investigated by electrochemical and gravimetric measurements in 3.5 wt.% NaCl at 22 Degree-Sign C. The alloys were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and surface potential maps. In Nd-containing alloys, formation of Al{sub 2}Nd and Al-Mn-Nd intermetallic compounds reduced the volume fraction and modified the morphology of the {beta}-Mg{sub 17}Al{sub 12} phase. The addition of Nd improved the corrosion resistance of the alloys due to increased passivity of the surface film and suppression of micro-galvanic couples.

  4. Producing nano-grained and Al-enriched surface microstructure on AZ91 magnesium alloy by high current pulsed electron beam treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Shengzhi, E-mail: ebeam@dlut.edu.cn; Li, Mincai

    2016-05-15

    Highlights: • HCPEB surface treatment was conducted on AZ91 magnesium alloy. • Surface modified microstructure and phase composition were characterized. • Preferential evaporation of Mg and dissolution of Mg{sub 17}Al{sub 12} phase occurred. • Nano-grained and Al-enriched surface layer was produced of depth ∼8 μm. • Surface microhardness and corrosion resistance were improved simultaneously. - Abstract: Surface treatment of AZ91 magnesium alloy was carried out by high current pulsed electron beam (HCPEB) with accelerating voltage 27 kV and energy density 3 J/cm{sup 2}. The surface microstructure and phase composition were characterized by using optical microscope (OM), X-ray diffraction (XRD), and scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). The surface microhardness and corrosion resistance were measured. Under HCPEB treatments, the preferential evaporation of Mg element occurred intensively on irradiated surface and the initial large Mg{sub 17}Al{sub 12} phases were dissolved. The nano-grained and Al-enriched surface modified layer was ultimately formed of depth ∼8 μm. According to the testing results, the surface microhardness increased from 63 to 141 HK after 30 pulses of HCPEB treatment, while the best improvement of corrosion resistance was obtained by 15 pulses of HCPEB treatment with a cathodic current density decreased by two orders of magnitude as compared with the initial AZ91 sample.

  5. A novel simple strategy for in situ deposition of apatite layer on AZ31B magnesium alloy for bone tissue regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Mousa, Hamouda M. [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Department of Engineering Materials and Mechanical Design, Faculty of Engineering, South Valley University, Qena 83523 (Egypt); Lee, Do Hee [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Park, Chan Hee, E-mail: biochan@jbnu.ac.kr [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Kim, Cheol Sang, E-mail: chskim@jbnu.ac.kr [Department of Bionanosystem Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

    2015-10-01

    Graphical abstract: - Highlights: • Anodizing process was used for the surface modification of AZ31B magnesium alloy. • An appetite-like film was deposited on the surface of AZ31B magnesium alloy. • Ceramic film was investigated by XRD and XPS. • Nano-plates growth are observed though the implemented experimental design. • Significant increase in the substrate hardness and surface roughness was observed. - Abstract: In this study, for the first time, the degradation performance of AZ31B Mg alloy was tuned by an in situ deposition of apatite thin layer within a short time in one step. Using Taguchi method for experimental design, anodization process was designed under control conditions (time and voltage), and simulated body fluid (SBF) was used as the electrolyte to nucleate apatite-like compounds. The coated alloy was characterized through field emission scanning electron microscopy (FE-SEM), EDS, X-ray diffraction and XPS analysis. The results show that the applied voltage has a significant effect on the formation of apatite-like layers. Compared to the uncoated samples, microhardness and surface roughness of the coated samples showed remarkably different values. The potentiodynamic polarization results demonstrate that the polarization resistance of the anodized samples is higher than the substrate polarization resistance, thus improving the alloy corrosion resistant. Based on the experimental results, the proposed nanostructure apatite-like coating can offer a promising way to improve the biocompatibility and degradability properties of the Mg alloy for bone tissue regeneration.

  6. Microstructure Correlation with Formability for Biaxial Stretching of Magnesium Alloy AZ31B at Mildly Elevated Temperatures

    Science.gov (United States)

    Chelladurai, Isaac; Miles, Michael P.; Fullwood, David T.; Carsley, John E.; Mishra, Raj K.; Beyerlein, Irene J.; Knezevic, Marko

    2017-05-01

    Magnesium AZ31B sheets of 2 mm thickness were stretch formed with a 101.6-mm-diameter punch at temperatures from 25°C to 150°C, in 25°C increments. Surface strains were measured with a digital image correlation method. The punch height versus load curve was found to be the same for temperatures of 25°C and for 50°C, whereas at 75°C and above, the load for a given punch height started to decrease, indicating a potential change in deformation mechanism. Electron backscatter diffraction was used to quantify features of the microstructure in the tested specimens. In particular, the gradual decrease in twinning activity as a result of easier thermally activated slip with increasing temperatures is quantified across this range. Moreover, twin activity was found to predominantly involve the formation of \\{{10\\bar{1}1} \\} compression twins that rapidly transform to create secondary twins for easier strain accommodation.

  7. Enhanced corrosion resistance and biocompatibility of AZ31 Mg alloy using PCL/ZnO NPs via electrospinning

    Science.gov (United States)

    Kim, Jinwoo; Mousa, Hamouda M.; Park, Chan Hee; Kim, Cheol Sang

    2017-02-01

    In the efforts to improve corrosion resistance and biocompatibility of magnesium alloys, polycarprolactone (PCL) and zinc oxide nanoparticles (ZnO NPs) composite coatings were applied onto AZ31 Mg alloys via electrospinning technique in this study. The PCL/ZnO composite coatings on Mg alloys were characterized by using FE-SEM, EDX, XPS, and FT-IR. Moreover, coating adhesion test, electrochemical corrosion test, and biocompatibility test in vitro were performed to measure coating performance. Our results revealed that the increase in the content of ZnO NPs in the composite coatings not only improved the coating adhesion of composite coatings on Mg alloys, but also increased the corrosion resistance. Furthermore, the biocompatibility of MC3T3-E1 osteoblasts of the PCL/ZnO composite coated samples was superior to the biocompatibility of the bare samples. Such data suggest that applying PCL/ZnO composite coating to the magnesium alloys has suitable potential in biomedical applications.

  8. Influence of welding parameter on texture distribution and plastic deformation behavior of as-rolled AZ31 Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Renlong, E-mail: rlxin@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing (China); State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing (China); Liu, Dejia; Shu, Xiaogang; Li, Bo; Yang, Xiaofang; Liu, Qing [College of Materials Science and Engineering, Chongqing University, Chongqing (China)

    2016-06-15

    Friction stir welding (FSW) has promising application potential for Mg alloys. However, softening was frequently occurred in FSW Mg joints because of the presence of a β-type fiber texture. The present study aims to understand the influence of texture distribution in stir zone (SZ) on deformation behavior and joint strength of FSW Mg welds. AZ31 Mg alloy joints were obtained by FSW with two sets of welding speed and rotation rate. Detailed microstructure and texture evolutions were examined on Mg welds by electron backscatter diffraction (EBSD) techniques. It was found that the changes of welding parameters can affect texture distribution and the characteristic of texture in the transition region between SZ and thermal-mechanical affected zone (TMAZ). As a consequence, the activation ability of basal slip and extension twinning was changed, which therefore influenced joint strength, inhomogeneous plastic deformation and fracture behaviors. The present work provided some insights into understanding the texture–property relationship in FSW Mg welds and indicated that it is effective to tailor the joint performance by texture control. - Highlights: • Welding parameters largely affect the inclination angle of SZ/TMAZ boundary. • Fracture morphology is associated with the characteristic of SZ/TMAZ boundary. • The characteristic of plastic deformation is explained from the activation of basal slip.

  9. AzTEC Survey of the Central Molecular Zone: Modeling Dust SEDs and N-PDF with Hierarchical Bayesian Analysis

    Science.gov (United States)

    Tang, Yuping; Wang, Daniel; Wilson, Grant; Gutermuth, Robert; Heyer, Mark

    2018-01-01

    We present the AzTEC/LMT survey of dust continuum at 1.1mm on the central ˜ 200pc (CMZ) of our Galaxy. A joint SED analysis of all existing dust continuum surveys on the CMZ is performed, from 160µm to 1.1mm. Our analysis follows a MCMC sampling strategy incorporating the knowledge of PSFs in different maps, which provides unprecedented spacial resolution on distributions of dust temperature, column density and emissivity index. The dense clumps in the CMZ typically show low dust temperature ( 20K), with no significant sign of buried star formation, and a weak evolution of higher emissivity index toward dense peak. A new model is proposed, allowing for varying dust temperature inside a cloud and self-shielding of dust emission, which leads to similar conclusions on dust temperature and grain properties. We further apply a hierarchical Bayesian analysis to infer the column density probability distribution function (N-PDF), while simultaneously removing the Galactic foreground and background emission. The N-PDF shows a steep power-law profile with α > 3, indicating that formation of dense structures are suppressed.

  10. The Development of Spheroidal Grains and Thixoforming of AZ91D Magnesium Alloy Treated by Different Routes

    Directory of Open Access Journals (Sweden)

    Gaozhan ZHAO

    2014-12-01

    Full Text Available A new process squeeze casting-solid extrusion was introduced to prepare semi-solid billets for thixoforging together with partial remelting. The microstructure development and tensile properties of AZ91D alloy reheated from states of as-cast and SCSE-formed were researched. During partial remelting, samples from SCSE-formed obtained finer and more uniform microstructure obviously than from as-cast. As the holding time went on, both solid particles from the two states experienced continuous spheroidization, and in the meantime from SCSE-formed were always to coarsen, while from as-cast were refined initially and coarsened then. Microstructure development is determined by the combination effects of various factors, including distortion energy from SCSE deformation, grain coalescence, Ostwald ripening mechanism, etc. During thixoforging, components with good forming quality were prepared successfully. Excellent tensile properties were obtained for the thixoforged alloy prepared by SCSE deformation, mainly with the microstructure refinement and the decrease of defects related. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6482

  11. Corrosion performance of MAO coatings on AZ31 Mg alloy in simulated body fluid vs. Earle's Balance Salt Solution

    Science.gov (United States)

    Wilke, Benjamin M.; Zhang, Lei; Li, Weiping; Ning, Chengyun; Chen, Cheng-fu; Gu, Yanhong

    2016-02-01

    Earle's Balance Salt Solution (EBSS) provides an alternative to the conventional simulated body fluids (c-SBF) and has been shown to better simulate the corrosion conditions in vivo. In this work, a series of tests were conducted to explore the corrosion performance of MAO-coated AZ31 samples in EBSS vs. c-SBF. Samples were produced by varying MAO process parameters and then immersed up to 21 days in both EBSS and c-SBF. The corrosion rates were evaluated by the electrochemical impedance spectroscopy and potentiodynamic scanning. Scanning electron microscope (SEM) was used to compare the progression of microcracks across the surface of the coatings. The evaluation of cross-sectional thickness showed an increase in MAO coating thickness with the process voltage. MAO samples with a thicker coating generally have higher impedance and lower current density at the initial immersion time point of 0.5 h. Samples in EBSS showed higher initial impedance and lower current density values as compared to c-SBF counterparts for all process groups. Samples in EBSS demonstrated a much slower corrosion rate than c-SBF samples because of the decreased chloride content and CO2 buffering mechanism of the EBSS.

  12. Effect of Melt Temperature on Surface Films Formed on Molten AZ91D Alloy Protected by Graphite Powder

    Science.gov (United States)

    Li, Weihong; Zhou, Jixue; Ma, Baichang; Wang, Jinwei; Wu, Jianhua; Yang, Yuansheng

    2017-08-01

    Graphite powder was adopted to prevent AZ91D alloy from oxidizing during melting and casting. The microstructure of the resultant surface films, formed at 933 K, 973 K, 1013 K, and 1053 K (660 °C, 700 °C, 740 °C, and 780 °C) for 30 minutes, was investigated by scanning electron microscopy, energy dispersive spectrometer, and X-ray diffraction, and the phase composition of the surface films was analyzed by the standard Gibbs free energy change of the reactions between the graphite powder, the alloy melt, and the ambient atmosphere. The effect and mechanism of melt temperature on the resultant surface films were also discussed. The results indicated that the surface films, of which the surface morphology comprised folds and wrinkles, were composed of a protective layer and MgF2 particles. The protective layer was contributive to the prevention of the molten alloy from oxidizing, and consisted of magnesium, oxygen, fluorine, carbon, and a small amount of aluminium existing in the form of MgO, MgF2, C, and MgAl2O4. The layer thickness was 200 to 900 nm. The melt temperature may affect the surface films through the increased interaction between the graphite powder, the melt, and the ambient atmosphere. The oxygen content and thickness of the protective layer decreased and then increased, while the height of the folds increased with melt temperature.

  13. Influence of 8-hydroxyquinoline on properties of anodic coatings obtained by micro arc oxidation on AZ91 magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, R.F. [Jiangxi Key Laboratory of Surface Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); School of Material Science and Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Zhang, S.F., E-mail: zhangshufang790314@sina.com [Jiangxi Key Laboratory of Surface Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); School of Material Science and Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China); Yang, N.; Yao, L.J.; He, F.X.; Zhou, Y.P.; Xu, X.; Chang, L.; Bai, S.J. [School of Material Science and Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013 (China)

    2012-10-25

    Highlights: Black-Right-Pointing-Pointer 8-HQ can promote the coating formation and change the coating color. Black-Right-Pointing-Pointer 8-HQ can increase the coating thickness and decrease the pore size. Black-Right-Pointing-Pointer Insoluble Mg(HQ){sub 2} is formed in anodic coatings in an alkaline solution with 8-HQ. Black-Right-Pointing-Pointer 8-HQ improves the corrosion resistance of the anodized magnesium alloys. - Abstract: The influence of 8-hydroxyquinoline (8-HQ) on formation and properties of anodic coatings obtained by micro arc oxidation (MAO) on AZ91 magnesium alloys was studied by scanning electron microscope (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared (FT-IR) spectroscopy and potentiodynamic polarization tests. The results demonstrate that 8-HQ can decrease the solution conductivity, take part in the coating formation and change the coating color. By developing anodic coatings with increasing thickness, insoluble Mg(HQ){sub 2} and small pore size, 8-HQ improves the corrosion resistance of the anodized magnesium alloys. The coating shows the best corrosion resistance in the solution of 10 g/L NaOH and 18 g/L Na{sub 2}SiO{sub 3} with 2 g/L 8-HQ.

  14. Halogen-Free Phosphonate Ionic Liquids as Precursors of Abrasion Resistant Surface Layers on AZ31B Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Tulia Espinosa

    2015-01-01

    Full Text Available Surface coatings formed by immersion in the ionic liquids (ILs 1,3-dimethylimidazolium methylphosphonate (LMP101, 1-ethyl-3-methylimidazolium methylphosphonate (LMP102 and 1-ethyl-3-methylimidazolium ethylphosphonate (LEP102 on magnesium alloy AZ31B at 50 °C have been studied. The purpose of increasing the temperature was to reduce the immersion time, from 14 days at room temperature, to 48 hours at 50 °C. The abrasion resistance of the coated alloy was studied by microscratching under progressively increasing load, and compared with that of the uncoated material. The order of abrasion resistance as a function of the IL is LEP102 > LMP101 > LMP102, which is in agreement with the order obtained for the coatings grown at room temperature. The maximum reduction in penetration depth with respect to the uncovered alloy, of a 44.5%, is obtained for the sample treated with the ethylphosphonate LEP102. However, this reduction is lower than that obtained when the coating is grown at room temperature. This is attributed to the increased thickness and lower adhesion of the coatings obtained at 50 °C, particularly those obtained from methylphosphonate ionic liquids. The results are discussed from SEM-EDX and profilometry.

  15. Correlación entre materia grasa, azúcares reductores y humedad en la pulpa de aceitunas

    Directory of Open Access Journals (Sweden)

    Sánchez Gómez, A. H.

    1991-12-01

    Full Text Available Statistical analysis of the results obtained for fat, reducing sugars, and moisture, in the fresh pulp of olives from two Spanish varieties, Gordal and Zorzaleña, and one of Greek origin, Conservolea, during the growth and ripening period, gives rise to a multiple regression equation, which is valid for the three considered varieties. No significant differences, related to variety, crop, and culture region, were found in this study.

    En aceitunas de dos variedades españolas, Gordal y Zorzaleña, y una de origen griego, Conservolea, se realiza un análisis estadístico de los resultados obtenidos durante el desarrollo y maduración del fruto, en la determinación de los componentes mayoritarios de la pulpa fresca, materia grasa, azúcares reductores y humedad. Se obtiene una ecuación global de regresión múltiple, no encontrándose diferencias significativas atribuibles a la variedad, campaña, y región consideradas en el estudio.

  16. Microstructure and mechanical properties of AZ91 tubes fabricated by Multi-pass Parallel Tubular Channel Angular Pressing

    Directory of Open Access Journals (Sweden)

    Hooman Abdolvand

    2017-06-01

    Full Text Available Parallel Tubular Channel Angular Pressing (PTCAP process is a novel recently developed severe plastic deformation (SPD method for producing ultrafine grained (UFG and nanograined (NG tubular specimens with excellent mechanical and physical properties. This process has several advantageous compared to its TCAP counterparts. In this paper, a fine grained AZ91 tube was fabricated via multi pass parallel tubular channel angular pressing (PTCAP process. Tubes were processed up to three passes PTCAP at 300 °C. Evolution of microstructure, mechanical properties and fracture behavior of the processed tubes after different passes were evaluated. Hardness, strength, and elongation were increased for processed tubes. Mean grain size was notably reduced to 3.8 μm for the tube which processed three passes from a 150 μm for the unprocessed tube. The maximum strength was found for second passes PTCAP processed tube which increased considerably about 108 %. The strength of the first pass processed tube increased about 62.5%. Increasing in elongation at room temperature was occurred, too. Mechanical properties of the third pass processed tube were deteriorated relatively because of appearing microcracks on the surface. Also, the hardness improved and it was increased about 77%. The result showed that the achieved mechanical properties consistent with microstructure.

  17. Dual-beam laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration

    Science.gov (United States)

    Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

    2014-03-01

    Porosity within laser welds of magnesium alloys is one of the main roadblocks to achieving high quality joints. One of the causes of pore formation is the presence of pre-existing coatings on the surface of magnesium alloy such as oxide or chromate layers. In this study, single-beam and dual-beam laser heat sources are investigated in relation to mitigation of pores resulting from the presence of the as-received oxide layer on the surface of AZ31B-H24 magnesium alloy during the laser welding process. A fiber laser with a power of up to 4 kW is used to weld samples in a zero-gap lap joint configuration. The effect of dual-beam laser welding with different beam energy ratios is studied on the quality of the weld bead. The purpose of this paper is to identify the beam ratio that best mitigates pore formation in the weld bead. The laser molten pool and the keyhole condition, as well as laser-induced plasma plume are monitored in real-time by use of a high speed charge-coupled device (CCD) camera assisted with a green laser as an illumination source. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. Results showed that a dual-beam laser configuration can effectively mitigate pore formation in the weld bead by a preheating-welding mechanism.

  18. Mechanical Behavior of AZ31B Mg Alloy Sheets under Monotonic and Cyclic Loadings at Room and Moderately Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Ngoc-Trung Nguyen

    2014-02-01

    Full Text Available Large-strain monotonic and cyclic loading tests of AZ31B magnesium alloy sheets were performed with a newly developed testing system, at different temperatures, ranging from room temperature to 250 °C. Behaviors showing significant twinning during initial in-plane compression and untwinning in subsequent tension at and slightly above room temperature were recorded. Strong yielding asymmetry and nonlinear hardening behavior were also revealed. Considerable Bauschinger effects, transient behavior, and variable permanent softening responses were observed near room temperature, but these were reduced and almost disappeared as the temperature increased. Different stress–strain responses were inherent to the activation of twinning at lower temperatures and non-basal slip systems at elevated temperatures. A critical temperature was identified to account for the transition between the twinning-dominant and slip-dominant deformation mechanisms. Accordingly, below the transition point, stress–strain curves of cyclic loading tests exhibited concave-up shapes for compression or compression following tension, and an unusual S-shape for tension following compression. This unusual shape disappeared when the temperature was above the transition point. Shrinkage of the elastic range and variation in Young’s modulus due to plastic strain deformation during stress reversals were also observed. The texture-induced anisotropy of both the elastic and plastic behaviors was characterized experimentally.

  19. Transient liquid phase bonding of magnesium alloys AZ31 using nickel coatings and high frequency induction heat sintering

    Directory of Open Access Journals (Sweden)

    A.N. AlHazaa

    2016-04-01

    Full Text Available Transient liquid phase (TLP bonding process was applied to join magnesium alloy AZ31 samples with minimum microstructural changes. The magnesium samples were coated by 5 μm nickel prior to the TLP bonding. Bonding conditions of 8 MPa uniaxial pressure and 520 °C bonding temperature were applied for all bonds at various bonding times. The microstructure across the joint regions was examined as a function of bonding time (5–60 min. Investigating the change in Ni contents was examined by EDS line scan. It was noticed that Ni coating could not be observed by SEM for bonds made at 30 and 60 min due to complete dissolution of the Ni coating. Second phase particles containing Mg2Ni intermetallics were observed by X-ray Photoelectron Spectroscopy (XPS near the joint region. The shear strength of the bonds initially increases with the increase in bonding time till 20 min. On the other hand, with bonding times over 20 min the shear strength decreases. Therefore the optimum bonding time at the conditions applied was concluded to be 20 min.

  20. Effect of Cerium Oxide on Morphologies and Electrochemical Properties of Ni-W-P Coating on AZ91D Magnesium

    Science.gov (United States)

    Sun, Wan-chang; Xu, Jia-Min; Wang, Yuan; Guo, Fang; Jia, Zong-Wei

    2017-10-01

    AZ91D magnesium alloy substrate was first pretreated in a phosphoric acid to obtain a phosphate coating, and then, the electroless ternary Ni-W-P coating was deposited using a sulfate nickel bath. The morphologies of the Ni-W-P coating were observed by using scanning electron microscope, the deposition rate of the coating was examined with the method of gravimetric analysis, and the phase analysis was identified by x-ray diffractometer. Electrochemical property was tested by means of an electrochemical analyzer. The results indicated that the addition of an optimum concentration of CeO2 (cerium oxide) particles could evidently improve the deposition rate and the stability of the plating bath. However, it acted as an inhibiting effect as the concentration of CeO2 particles exceeded to 8 mg/L in the sulfate nickel bath. The results also revealed that the morphology of Ni-W-P coating became more smooth, compact and uniform with the increase in the concentrations of CeO2 particles in the bath, but the corrosion resistance decreased due to the precipitation of crystal phases (Ni3P, Ni4W, etc.) after heat treatment.

  1. Development of Zirconium-based Conversion Coatings for the Pretreatment of AZ91D Magnesium Alloy Prior to Electrocoating

    Science.gov (United States)

    Reck, James; Wang, Yar-Ming; Kuo, Hong-Hsiang Harry

    This work examines the use of hexafluorozirconic acid based solutions at concentrations from 0.025 M to 0.100 M and pH values of 2.0 to 4.0 for the creation of a zirconia-based conversion coating less than 1 micron thick to protect magnesium alloy AZ91D. Similar coatings have been found to give excellent protection for steel and aluminum alloys, but little research has been conducted on its application to magnesium. Work was performed to gain an understanding of the film formation mechanisms and related kinetics using x-ray photo-electron spectroscopy, scanning electron microscopy, and open circuit potential monitoring techniques. A design of experiments approach was taken to determine the effects of acid concentration, pH, and soak time on the corrosion properties both as-deposited and with an application of electrocoat. It was found that the application of the zirconia-based coating significantly increased corrosion resistance, and allowed for an acceptable e-coat application with excellent adherence.

  2. Corrosion resistance of Zn-Al layered double hydroxide/poly(lactic acid) composite coating on magnesium alloy AZ31

    Science.gov (United States)

    Zeng, Rong-Chang; Li, Xiao-Ting; Liu, Zhen-Guo; Zhang, Fen; Li, Shuo-Qi; Cui, Hong-Zhi

    2015-12-01

    A Zn-Al layered double hydroxide (ZnAl-LDH) coating consisted of uniform hexagonal nano-plates was firstly synthesized by co-precipitation and hydrothermal treatment on the AZ31 alloy, and then a poly(lactic acid) (PLA) coating was sealed on the top layer of the ZnAl-LDH coating using vacuum freeze-drying. The characteristics of the ZnAl-LDH/PLA composite coatings were investigated by means of XRD, SEM, FTIR and EDS. The corrosion resistance of the coatings was assessed by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the ZnAl-LDH coating contained a compact inner layer and a porous outer layer, and the PLA coating with a strong adhesion to the porous outer layer can prolong the service life of the ZnAl-LDH coating. The excellent corrosion resistance of this composite coating can be attributable to its barrier function, ion-exchange and self-healing ability.

  3. Corrosion performance of atmospheric plasma sprayed alumina coatings on AZ31B magnesium alloy under immersion environment

    Directory of Open Access Journals (Sweden)

    D. Thirumalaikumarasamy

    2014-12-01

    Full Text Available Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. The alumina powders were plasma sprayed on AZ31B magnesium alloy with three different plasma spraying parameters. In the present work, the influence of plasma spray parameters on the corrosion behavior of the coatings was investigated. The corrosion behavior of the coated samples was evaluated by immersion corrosion test in 3.5 wt% NaCl solution. Empirical relationship was established to predict the corrosion rate of plasma sprayed alumina coatings by incorporating process parameters. The experiments were conducted based on a three factor, five-level, central composite rotatable design matrix. The developed relationship can be effectively used to predict the corrosion rate of alumina coatings at 95% confidence level. The results indicate that the input power has the greatest influence on corrosion rate, followed by stand-off distance and powder feed rate.

  4. The Effect of Short Duration Electric Current on the Quasi-Static Tensile Behavior of Magnesium AZ31 Alloy

    Directory of Open Access Journals (Sweden)

    Trung Thien Nguyen

    2016-01-01

    Full Text Available The effect of a single pulse of electric current with short duration on the quasi-static tensile behavior of a magnesium AZ31 alloy is experimentally investigated. A single pulse of electric current with duration less than 1 second is applied to the specimen, while the specimen is being deformed in the plastic region under quasi-static tensile loads. After a nearly instant decrease of flow stress at the pulse of electric current, the flow stress shows strain hardening until the failure of the specimen. The experimental result shows that the strain-hardening parameters (the strength coefficient and the strain-hardening exponent of the hardening curve after the electric current strongly depend on the applied electric energy density (electric energy per unit volume. Empirical expressions are suggested to describe the hardening behavior after the pulse as a function of the electric energy density and are compared with the empirical expressions suggested for advanced high-strength steels.

  5. A MOBIL INTERNET TECHNOLÓGIAI, GAZDASÃ GI ÉS TÃ RSADALMI HATÃ SAI AZ AGRÃ RGAZDASÃ GBAN

    OpenAIRE

    Szilagyi, Robert; Herdon, Miklos

    2005-01-01

    A mobil kommunikáció, ezen belül a mobil Internet az agrárgazdaság számá-ra a használat hely és idő függetlensége miatt fontos lehetőséget, gazdasági elő-nyöket, a vállalkozások, szervezetek számára hatékonyabb működést jelenthet. Széleskörű elterjedése, innovációs hatása és előnyei gazdaságosan csak a technológia és a szolgáltatások hatásrendszerének figyelembevételével érhető el. A technológiai, társadalmi és gazdasági komplex hatásrendszer befolyásolja a gazdasági alkalmazások terjedését. ...

  6. Robust Slippery Coating with Superior Corrosion Resistance and Anti-Icing Performance for AZ31B Mg Alloy Protection.

    Science.gov (United States)

    Zhang, Jialei; Gu, Changdong; Tu, Jiangping

    2017-03-29

    Biomimetic slippery liquid-infused porous surfaces (SLIPSs) are developed as a potential alternative to superhydrophobic surfaces (SHSs) to resolve the issues of poor durability in corrosion protection and susceptibility to frosting. Herein, we fabricated a double-layered SLIPS coating on the AZ31 Mg alloy for corrosion protection and anti-icing application. The porous top layer was infused by lubricant, and the compact underlayer was utilized as a corrosion barrier. The water-repellent SLIPS coating exhibits a small sliding angle and durable corrosion resistance compared with the SHS coating. Moreover, the SLIPS coating delivers durable anti-icing performance for the Mg alloy substrate, which is obviously superior to the SHS coating. Multiple barriers in the SLIPS coating, including the infused water-repellent lubricant, the self-assembled monolayers coated porous top layer, and the compact layered double hydroxide-carbonate composite underlayer, are suggested as being responsible for the enhanced corrosion resistance and anti-icing performance. The robust double-layered SLIPS coating should be of great importance to expanding the potential applications of light metals and their alloys.

  7. Effect of Cerium Oxide on Morphologies and Electrochemical Properties of Ni-W-P Coating on AZ91D Magnesium

    Science.gov (United States)

    Sun, Wan-chang; Xu, Jia-Min; Wang, Yuan; Guo, Fang; Jia, Zong-Wei

    2017-12-01

    AZ91D magnesium alloy substrate was first pretreated in a phosphoric acid to obtain a phosphate coating, and then, the electroless ternary Ni-W-P coating was deposited using a sulfate nickel bath. The morphologies of the Ni-W-P coating were observed by using scanning electron microscope, the deposition rate of the coating was examined with the method of gravimetric analysis, and the phase analysis was identified by x-ray diffractometer. Electrochemical property was tested by means of an electrochemical analyzer. The results indicated that the addition of an optimum concentration of CeO2 (cerium oxide) particles could evidently improve the deposition rate and the stability of the plating bath. However, it acted as an inhibiting effect as the concentration of CeO2 particles exceeded to 8 mg/L in the sulfate nickel bath. The results also revealed that the morphology of Ni-W-P coating became more smooth, compact and uniform with the increase in the concentrations of CeO2 particles in the bath, but the corrosion resistance decreased due to the precipitation of crystal phases (Ni3P, Ni4W, etc.) after heat treatment.

  8. Microstructure and Mechanical Properties of Fiber-Laser-Welded and Diode-Laser-Welded AZ31 Magnesium Alloy

    Science.gov (United States)

    Chowdhury, S. M.; Chen, D. L.; Bhole, S. D.; Powidajko, E.; Weckman, D. C.; Zhou, Y.

    2011-07-01

    The microstructures, tensile properties, strain hardening, and fatigue strength of fiber-laser-welded (FLW) and diode-laser-welded (DLW) AZ31B-H24 magnesium alloys were studied. Columnar dendrites near the fusion zone (FZ) boundary and equiaxed dendrites at the center of FZ, with divorced eutectic β-Mg17Al12 particles, were observed. The FLW joints had smaller dendrite cell sizes with a narrower FZ than the DLW joints. The heat-affected zone consisted of recrystallized grains. Although the DLW joints fractured at the center of FZ and exhibited lower yield strength (YS), ultimate tensile strength (UTS), and fatigue strength, the FLW joints failed at the fusion boundary and displayed only moderate reduction in the YS, UTS, and fatigue strength with a joint efficiency of ~91 pct. After welding, the strain rate sensitivity basically vanished, and the DLW joints exhibited higher strain-hardening capacity. Stage III hardening occurred after yielding in both base metal (BM) and welded samples. Dimple-like ductile fracture characteristics appeared in the BM, whereas some cleavage-like flat facets together with dimples and river marking were observed in the welded samples. Fatigue crack initiated from the specimen surface or near-surface defects, and crack propagation was characterized by the formation of fatigue striations along with secondary cracks.

  9. Transient Liquid Phase Bonding of Magnesium Alloy AZ31 Using Cu Coatings and Cu Coatings with Sn Interlayers

    Directory of Open Access Journals (Sweden)

    Abdulaziz Nasser AlHazaa

    2018-01-01

    Full Text Available Transient liquid phase bonding (TLP of AZ31 samples has been investigated using Cu coatings and Cu coatings with Sn interlayer. Copper coatings were used for one set of the bonds, and a combination of Cu coatings and Sn interlayer was used for the other set of bonds. The bonding temperature was fixed at 520 °C, and various bonding times were applied. This study shows that the bonds produced using only Cu coatings have shown weaker bonds compared to the bonds made using Cu coatings and Sn interlayer. The Cu2Mg particles were detected at the joint region of both bonds made by Cu coatings and Cu coatings with Sn interlayer by X-ray diffraction (XRD. However, it has been observed that the joint region was dominated by solid solution which is rich in Mg. Sn interlayer was not contributed to the intermetallic compound (IMC at the joint region, and therefore it was diffused away through the Mg matrix. Within the joint interface, a slight increase of micro-hardness was observed compared to Mg base metal alloy. This was attributed to the formation and presence of IMC’s within the joint region. It was noticed that the presence of the Sn interlayer improved the joint strength by reducing the pores at the joint region. Pores were clearly observed for those bonds made using Cu coatings—especially for region where the fracture occurs; this was accomplished by scanning electron microscope (SEM.

  10. Surface properties of AZ91 magnesium alloy after PEO treatment using molybdate salts and low current densities

    Energy Technology Data Exchange (ETDEWEB)

    Pezzato, Luca, E-mail: luca.pezzato@studenti.unipd.it [Department of Industrial Engineering, University of Padua, Via Marzolo 9, 35131 Padova (Italy); Brunelli, Katya [Department of Industrial Engineering, University of Padua, Via Marzolo 9, 35131 Padova (Italy); Napolitani, Enrico [MATIS-IMM-CNR and Dipartimento di Astronomia e Fisica, University of Padua, Via Marzolo 8, 35131 Padova (Italy); Magrini, Maurizio; Dabalà, Manuele [Department of Industrial Engineering, University of Padua, Via Marzolo 9, 35131 Padova (Italy)

    2015-12-01

    Graphical abstract: - Highlights: • Low concentrations of molybdate stopped PEO process at the first step. • High concentrations of molybdate produce the start of the second and third stages. • The layer after the first step is thin but dense and homogeneous. • The sample treated with low amount of molybdate is the one with best corrosion resistance. - Abstract: Plasma electrolytic oxidation (PEO) process is a recently developed electrochemical method used to produce on the surface of various metals oxide ceramic coatings that improve corrosion and wear properties of the substrate. In this work, PEO process was applied on AZ91 magnesium alloy using low current densities (0.05 A/cm{sup 2}) and an alkaline solution of silicates with different concentrations of sodium molybdate (0.3–3 g/l). The effect of the low current densities of process and of molybdate salts on the corrosion resistance of the coatings was studied with potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) in chloride and sulfate environment. The morphology, the phases and the chemical composition of the coatings were examined using a scanning electron microscope equipped with EDS, X-ray diffraction, secondary ion mass spectrometry and X-ray photoelectron spectroscopy. The corrosion properties of the PEO coated samples were remarkably improved if compared with the uncoated samples. The addition of sodium molybdate, in determinate conditions, had a positive effect on the characteristics of the coatings in terms of corrosion resistance.

  11. Jeffreys's Nursing Universal Retention and Success model: overview and action ideas for optimizing outcomes A-Z.

    Science.gov (United States)

    Jeffreys, Marianne R

    2015-03-01

    Nursing student persistence, retention, and success are universally desired outcomes yet remain elusive and challenging worldwide. The aim of this study is to provide nurse educators with an organizing framework and action ideas for optimizing student outcomes. Jeffreys's Nursing Universal Retention and Success (NURS) model presents a globally-applicable framework for examining the multidimensional factors that affect undergraduate and graduate nursing student retention and success in order to make a positive difference. This article presents a brief overview of the empirically-based NURS model and indicates that retention decisions, persistence, and optimal outcomes will be based on the interaction of student profile characteristics, student affective factors, academic factors, environmental factors, academic outcomes, psychological outcomes, outside surrounding factors, and professional integration factors. An A-Z list of action ideas provides nurse educators with a springboard for further developing ideas tailored to individual program and student needs. Recommendations for global collaborative partnerships and networks are presented. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. The technology of preparing green coating by conducting micro-arc oxidation on AZ91D magnesium alloy

    Directory of Open Access Journals (Sweden)

    Wang Sheng

    2016-12-01

    Full Text Available Micro-arc oxidation was applied to AZ91D magnesium alloy by taking K2Cr2O7 as the colouring salt in the silicate system. It was shown that the green coating obtained through performing micro-arc oxidation on magnesium alloy consisted of Mg, Mg2SiO4, MgO, and MgCr2O4 based on analysis of X-ray diffraction (XRD, and scanning electron microscopy (SEM. Among which, MgCr2O4 was the colouring salt; there were something in the lamellar, pit, and convex forms found on the surface of the coating. The coating consisted of a porous, and a compact, layer from the outside to the inside. As demonstrated, the colour of the coating depended on the K2Cr2O7 concentration: it became gradually deeper with the addition of K2Cr2O7 and the increasing micro-arc oxidation time. The corrosion resistance and hardness of the green coating were greater than that of the matrix.

  13. Enhanced corrosion resistance and biocompatibility of AZ31 Mg alloy using PCL/ZnO NPs via electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jinwoo [Department of Bionanosystem Engineering, Graduate School, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Mousa, Hamouda M. [Department of Bionanosystem Engineering, Graduate School, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Department of Engineering Materials and Mechanical Design, Faculty of Engineering, South Valley University, Qena 83523 (Egypt); Park, Chan Hee, E-mail: biochan@jbnu.ac.kr [Department of Bionanosystem Engineering, Graduate School, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Kim, Cheol Sang, E-mail: chskim@jbnu.ac.kr [Department of Bionanosystem Engineering, Graduate School, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

    2017-02-28

    Highlights: • PCL/ZnO composite coating layer by electrospinning techniques showed the nano-scaled and porous surface structure. • Addition of zinc oxide NPs in the PCL fibers led to enhanced coating adhesion and corrosion resistance. • The composite coated surfaces on Mg substrates improved cell attachment and proliferation. - Abstract: In the efforts to improve corrosion resistance and biocompatibility of magnesium alloys, polycarprolactone (PCL) and zinc oxide nanoparticles (ZnO NPs) composite coatings were applied onto AZ31 Mg alloys via electrospinning technique in this study. The PCL/ZnO composite coatings on Mg alloys were characterized by using FE-SEM, EDX, XPS, and FT-IR. Moreover, coating adhesion test, electrochemical corrosion test, and biocompatibility test in vitro were performed to measure coating performance. Our results revealed that the increase in the content of ZnO NPs in the composite coatings not only improved the coating adhesion of composite coatings on Mg alloys, but also increased the corrosion resistance. Furthermore, the biocompatibility of MC3T3-E1 osteoblasts of the PCL/ZnO composite coated samples was superior to the biocompatibility of the bare samples. Such data suggest that applying PCL/ZnO composite coating to the magnesium alloys has suitable potential in biomedical applications.

  14. One step phase separation process to fabricate superhydrophobic PVC films and its corrosion prevention for AZ91D magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Na; Li, Jicheng; Bai, Ningning; Xu, Lan; Li, Qing, E-mail: liqingswu@163.com

    2016-07-15

    Graphical abstract: - Highlights: • Independent superhydrophobic polyvinyl chloride (PVC) film was prepared by phase separation process. • The superhydrophobic PVC film showed excellent stability in acid, alkali and salt corrosive solutions. • This film was prepared on magnesium surface protecting it from corrosion. • This method was simple and universal. - Abstract: A one step, simple fabrication method to prepare independent superhydrophobic polyvinyl chloride (PVC) coating is reported in this paper. The rough surface structure and low surface energy could be simply obtained only by a phase separation process. The independent PVC superhydrophobic film was also applied on AZ91D magnesium alloy. Scanning electron microscopy (SEM), water contact angle measurements, electrochemical test and adhesion tests have been performed to characterize the surface morphology, wettability, anti-corrosion and adhesion strength of independent PVC film and superhydrophobic magnesium alloy respectively. The results indicated that whether it was the PVC film or superhydrophobic magnesium, they show static contact angles higher than 150°, excellent anti-corrosion effect and adhesion strength. We believed that the presented method could provide a straightforward and simple route to fabricate low-cost and anti-corrosion coating on various substrate materials. Moreover, this one step process may find potential application in the field of industry because of its simplicity and universality.

  15. Effect of Holding Time on Surface Films Formed on Molten AZ91D Alloy Protected by Graphite Powder

    Science.gov (United States)

    Li, Weihong; Zhou, Jixue; Ma, Baichang; Wang, Jinwei; Wu, Jianhua; Yang, Yuansheng

    2017-10-01

    Graphite powder was adopted to prevent the AZ91D magnesium alloy from oxidizing during the melting and casting process. The microstructure of the resultant surface films formed at 973 K (700 °C) holding for 0, 15, 30, 45, and 60 minutes was investigated by scanning electron microscopy, energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) after mechanical polishing and chemical etching. The results indicated that the surface films were composed of a protective layer and the underneath particles with different morphology. The protective layer was continuous with a thickness of 200 to 1000 nm mainly consisting of MgO, MgF2, and C, while the underneath particles mainly consisted of MgF2 and MgAl2O4. The surface films were the result of the interaction between the graphite powder, the melt, and the ambient atmosphere. The number and the size of the underneath particles, determining the thickness uniformity of the surface films, and the unevenness of the microsurface morphology increased with holding time. The mechanism of holding time on the resultant surface films was also discussed.

  16. Exogenous application of abscisic acid (ABA) increases root and cell hydraulic conductivity and abundance of some aquaporin isoforms in the ABA-deficient barley mutant Az34

    Science.gov (United States)

    Sharipova, Guzel; Veselov, Dmitriy; Kudoyarova, Guzel; Fricke, Wieland; Dodd, Ian C.; Katsuhara, Maki; Furuichi, Takuya; Ivanov, Igor; Veselov, Stanislav

    2016-01-01

    Background and Aims Regulation of water channel aquaporins (AQPs) provides another mechanism by which abscisic acid (ABA) may influence water flow through plants. To the best of our knowledge, no studies have addressed the changes in ABA levels, the abundance of AQPs and root cell hydraulic conductivity (LpCell) in the same tissues. Thus, we followed the mechanisms by which ABA affects root hydraulics in an ABA-deficient barley mutant Az34 and its parental line ‘Steptoe’. We compared the abundance of AQPs and ABA in cells to determine spatial correlations between AQP abundance and local ABA concentrations in different root tissues. In addition, abundance of AQPs and ABA in cortex cells was related to LpCell. Methods Root hydraulic conductivity (LpRoot) was measured by means of root exudation analyses and LpCell using a cell pressure probe. The abundance of ABA and AQPs in root tissues was assessed through immunohistochemical analyses. Isoform-specific antibodies raised against HvPIP2;1, HvPIP2;2 and HvPIP2;5 were used. Key Results Immunolocalization revealed lower ABA levels in root tissues of Az34 compared with ‘Steptoe’. Root hydraulic conductivity (LpRoot) was lower in Az34, yet the abundance of HvPIPs in root tissues was similar in the two genotypes. Root hair formation occurred closer to the tip, while the length of the root hair zone was shorter in Az34 than in ‘Steptoe’. Application of external ABA to the root medium of Az34 and ‘Steptoe’ increased the immunostaining of root cells for ABA and for HvPIP2;1 and HvPIP2;2 especially in root epidermal cells and the cortical cell layer located beneath, parallel to an increase in LpRoot and LpCell. Treatment of roots with Fenton reagent, which inhibits AQP activity, prevented the ABA-induced increase in root hydraulic conductivity. Conclusion Shortly after (hydraulics through other mechanisms, in particular the developmental timing of the formation of root hairs closer to the root tip and the length

  17. Multi-annual climate in Parque Nacional Pan de Azúcar, Atacama Desert, Chile Clima multianual en el Parque Nacional Pan de Azúcar, Desierto de Atacama, Chile

    Directory of Open Access Journals (Sweden)

    MATTHEW V. THOMPSON

    2003-06-01

    Full Text Available The lomas formations of the Peruvian and Atacama deserts are characterized by both climatic and floristic spatial heterogeneity, as well as non-contiguous pockets of relatively distinct flora. We examined two distinct types of communities in Parque Nacional Pan de Azúcar in Chile, the low-elevation arroyo and bajada community, and the high-elevation fog-zone community. We determined the distribution with elevation of the dominant perennial plant species in a single arroyo community, as well as the distribution of associated climatic characteristics. Climatic conditions (including air temperature, relative humidity, and wind speed and direction were recorded from June, 1999, to March, 2001, for the arroyo, as well as for a medium-elevation inland site with little vegetation, and a high-elevation fog-zone site with copious vegetation. The fog layer, or camanchaca, derived from the marine inversion layer ubiquitous to the Peruvian and Atacama deserts was found to be more persistent, though weaker, during the summer months and somewhat more condensed and shallower in the winter months, with uncharacteristically dry air and high temperatures occurring at and above 400 m elevation during the late fall and early winter of 2000. The reduction or increase in the maximum elevation of the camanchaca or a change in the rainfall regime of the park may have broad implications for the distribution or even presence of certain species in Parque Nacional Pan de Azúcar. Vegetation patterns appear to be strongly dependent on inversion layer development, and perhaps on its subsidence during the winter. A number of species prevalent at low-elevation sites may have little advantage at a high-elevation foggy site, whereas the consistently high humidity at low elevations would be a boon to any desert plant accustomed to low precipitation. If we are to successfully assess the effects of changes in southern Pacific weather patterns, it will become necessary to more

  18. Competencia de Sicyos polyacanthus en caña de azúcar Interference of Sicyos polyacanthus in sugarcane

    Directory of Open Access Journals (Sweden)

    S. Chaila

    2004-12-01

    Full Text Available Se realizó este ensayo con el objeto de medir los efectos de la competencia permanente y especifica de S. polyacanthus sobre el cultivar CP 74-2005 en la localidad de Monte Rico (27º21'S-65º36'W, Tucumán-Argentina. El diseño experimental, completamente aleatorizado, se estableció en un cañaveral infestado naturalmente. Las parcelas fueron de 64 m² con cuatro surcos de diez metros de largo. Los efectos de la competencia fueron medidos en tres niveles de infestación: Alta (superior a 5 pl m-2, Media (1-4 pl m-2 y Baja (inferior a 1 pl m-2. Las mediciones se efectuaron sobre los dos surcos centrales de la parcela; para altura se analizó el promedio de diez mediciones por infestación y por repetición; y para producción de caña y de azúcar se trabajó con una muestra de caña por parcela, extraída del mismo sitio. Los efectos de la maleza en distinto grado de infestación sobre la altura del cañaveral fueron altamente significativos respecto del testigo obteniéndose pérdidas del 48,58% en baja infestación. En el número de tallos se encontraron pérdidas significativas en los diferentes niveles llegando a 61,87% en infestación alta. En la producción de caña por hectárea se produjeron perdidas de 43,89% en infestación media, mientras que en la producción de azúcar se registraron perdidas de 42,28 y 20,38% en infestación alta y baja respectivamente.This work aimed to measure the effects of permanent and specific interference of S. polyacanthus on CP 74-2005 sugarcane cultivar in Monte Rico (27º21'S-65º36'W (Tucumán province, Argentina. A complete randomized experimental design was carried out on a naturally infested sugarcane field. Each 64 m²-plot consisted of four ten-meter long furrows. The effects were measured at three infestation levels: high (more than 5 pl m-2, medium (1-4 pl m-2 and low (less than 1 pl m-2 . The measurements were taken on two central furrows in each plot. Height was taken by means of the average

  19. Preparation and corrosion resistance of magnesium phytic acid/hydroxyapatite composite coatings on biodegradable AZ31 magnesium alloy.

    Science.gov (United States)

    Zhang, Min; Cai, Shu; Zhang, Feiyang; Xu, Guohua; Wang, Fengwu; Yu, Nian; Wu, Xiaodong

    2017-06-01

    In this work, a magnesium phytic acid/hydroxyapatite composite coating was successfully prepared on AZ31 magnesium alloy substrate by chemical conversion deposition technology with the aim of improving its corrosion resistance and bioactivity. The influence of hydroxyapatite (HA) content on the microstructure and corrosion resistance of the coatings was investigated. The results showed that with the increase of HA content in phytic acid solution, the cracks on the surface of the coatings gradually reduced, which subsequently improved the corrosion resistance of these coated magnesium alloy. Electrochemical measurements in simulated body fluid (SBF) revealed that the composite coating with 45 wt.% HA addition exhibited superior surface integrity and significantly improved corrosion resistance compared with the single phytic acid conversion coating. The results of the immersion test in SBF showed that the composite coating could provide more effective protection for magnesium alloy substrate than that of the single phytic acid coating and showed good bioactivity. Magnesium phytic acid/hydroxyapatite composite, with the desired bioactivity, can be synthesized through chemical conversion deposition technology as protective coatings for surface modification of the biodegradable magnesium alloy implants. The design idea of the new type of biomaterial is belong to the concept of "third generation biomaterial". Corrosion behavior and bioactivity of coated magnesium alloy are the key issues during implantation. In this study, preparation and corrosion behavior of magnesium phytic acid/hydroxyapatite composite coatings on magnesium alloy were studied. The basic findings and significance of this paper are as follows: 1. A novel environmentally friendly, homogenous and crack-free magnesium phytic acid/hydroxyapatite composite coating was fabricated on AZ31 magnesium alloy via chemical conversion deposition technology with the aim of enhancing its corrosion resistance and

  20. Características y estabilidad aeróbica de ensilajes de caña de azúcar, tratada con urea, NaOH y maíz

    Directory of Open Access Journals (Sweden)

    W Santos da Silva

    Full Text Available El objetivo de esta investigación fue determinar el efecto de diferentes aditivos en la estabilidad aeróbica de la caña de azúcar, conservada como ensilaje en silos de laboratorio. Se determinó la materia seca (MS, el extracto etéreo (EE, la materia mineral (MM, la proteína bruta (PB, el pH y la estabilidad aeróbica del ensilaje tratado con urea, NaOH y maíz molido. Se utilizó un diseño completamente aleatorizado, con cuatro repeticiones, para evaluar los siguientes tratamientos: caña de azúcar sin aditivos, caña de azúcar + 4 % de maíz molido, caña de azúcar + 1 % de urea, caña de azúcar + 1 % de urea + 4 % de maíz molido, caña de azúcar + 1 % de NaOH, y caña de azúcar + 1 % de NaOH + 4 % de maíz molido. Los ensilajes tratados con urea tuvieron un mayor porcentaje de EE. En presencia de urea y NaOH, la adición de maíz molido aumentó significativamente la PB. El NaOH incrementó el porcentaje de MM. Las pérdidas de MS causadas por gases fueron significativamente mayores en los ensilajes que no recibieron aditivos químicos. Hubo diferencias significativas en la producción de CO2 en diferentes tiempos de exposición al aire. Se concluye que los aditivos mejoraron las características químicas, excepto el contenido de MS, y redujeron la pérdida por gases en la fermentación anaeróbica.

  1. Hemocompatibility and selective cell fate of polydopamine-assisted heparinized PEO/PLLA composite coating on biodegradable AZ31 alloy.

    Science.gov (United States)

    Wei, Zhongling; Tian, Peng; Liu, Xuanyong; Zhou, Bangxin

    2014-09-01

    Biodegradable magnesium and its alloys have attracted much attention, as they have been used as cardiovascular stents recently because of their biodegradation after implantation. However, their corrosion resistance, hemocompatibility and surface biocompatibility are needed for practical applications. In this work, heparinization of the plasma electrolytic oxidation/poly(l-lactic acid) (PEO/PLLA) composite coating on biodegradable AZ31 alloy was achieved by the strong adhesion of mussel-inspired polydopamine (PDAM). The corrosion resistance of the coated substrates was evaluated in simulated body fluid. In particular, the hemolysis ratio and platelet adhesion tests were conducted to evaluate the hemocompatibility of the composite coatings. The in vitro cytotoxicity of the composite coatings was evaluated with human umbilical vein endothelial cells (HUVECs). The adhesion and proliferation of HUVECs and human umbilical artery smooth muscle cells (HUASMCs) directly incubated on the composite coatings were also investigated. The results showed that although PDAM modification and further heparinization reduced the corrosion resistance of the PEO/PLLA composite coating, the protection of the coating for the substrate was mainly maintained. Moreover, PDAM modification and further heparinization significantly suppressed the adhesion of platelets and had little influence on sustaining a low hemolysis ratio thus resulting in good surface hemocompatibility of the composite coating. The in vitro cell test demonstrated that none of the composite coatings presented obvious cytotoxicity. Significantly, after surface heparinization, the composite coating became more suitable for HUVEC growth and simultaneously inhibited HUASMC growth. The results show that further modification of the PEO/PLLA composite coating on biodegradable magnesium alloy is a promising method to obtain good surface hemocompatibility for anticoagulation and to regulate the cell fate for fast re

  2. Expresión transitoria del gen GUS en caña de azúcar usando Agrobacterium tumefaciens

    Directory of Open Access Journals (Sweden)

    Martha Liliana Bonilla Betancourt

    2008-10-01

    Full Text Available En el estudio se desarrolló una metodología de transformación genética mediante Agrobacterium tumefaciens en cultivares colombianos de caña de azúcar. La transformación se evaluó mediante la expresión del gen GUS. Callos embriogénicos y explantes meristemáticos de los genotipos CC85-92, CC84-75 y CC87-505 se transformaron usando tres cepas (AGL-1, LBA4404 y EHA105 con el plásmido pCambia 1305.2 y dos (EHA105 y LBA4404 con pCambia 2301. Se usó el medio de infiltración (IM con acetosiringona y se evaluó el tiempo de cocultivo y la densidad óptica de la bacteria al momento de la inducción. Los genotipos mostraron respuesta diferencial con las combinaciones cepa-plásmido: obtuvieron mayor expresión del gen GUS cuando el genotipo CC85-92 se transformó con la cepa AGL-1-pCambia 1305.2. CC84-75 y CC87-505 mostraron mayor expresión cuando se transformaron con la cepa EHA105-pCambia 1305.2. Mayor eficiencia en la expresión se obtuvo cuando la bacteria se indujo en IM después de siete días de cocultivo y cuando la densidad óptica de la bacteria fue de 0.2(600nm al momento de la inducción. Se demostró superioridad de los explantes en la eficiencia de transformación.

  3. Continuum observations of M 51 and M 83 at 1.1 mm with AzTEC

    Science.gov (United States)

    Wall, W. F.; Puerari, I.; Tilanus, R.; Israel, F. P.; Austermann, J. E.; Aretxaga, I.; Wilson, G.; Yun, M.; Scott, K. S.; Perera, T. A.; Roberts, C. M.; Hughes, D. H.

    2016-06-01

    We observed the spiral galaxies M 51 and M 83 at 20 arscec spatial resolution with the bolometer array Aztronomical Thermal Emission Camera (AzTEC) on the JCMT in the 1.1 mm continuum, recovering the extended emission out to galactocentric radii of more than 12 kpc in both galaxies. The 1.1 mm-continuum fluxes are 5.6 ± 0.7 and 9.9 ± 1.4 Jy, with associated gas masses estimated at 9.4 × 109 M⊙ and 7.2 × 109 M⊙ for M 51 and M 83, respectively. In the interarm regions of both galaxies, the N(H2)/I(CO) (or X-factor) ratios exceed those in the arms by factors of ˜1.5-2. In the inner discs of both galaxies, the X-factor is about 1 × 1020 cm- 2 (K km s- 1)- 1. In the outer parts, the CO-dark molecular gas becomes more important. While the spiral density wave in M 51 appears to influence the interstellar medium and stars in a similar way, the bar potential in M 83 influences the interstellar medium and the stars differently. We confirm the result of Foyle et al. that the arms merely heighten the star formation rate (SFR) and the gas surface density in the same proportion. Our maps reveal a threshold gas surface density for an SFR increase by two or more orders of magnitude. In both galaxy centres, the molecular gas depletion time is about 1 Gyr climbing to 10-20 Gyr at radii of 6-8 kpc. This is consistent with an inside-out depletion of the molecular gas in the discs of spiral galaxies.

  4. Stepwise flow diagram for the development of formulations of non spore-forming bacteria against foliar pathogens: The case of Lysobacter capsici AZ78.

    Science.gov (United States)

    Segarra, Guillem; Puopolo, Gerardo; Giovannini, Oscar; Pertot, Ilaria

    2015-12-20

    The formulation is a significant step in biopesticide development and is an efficient way to obtain consistency in terms of biological control under field conditions. Nonetheless, there is still a lack of information regarding the processes needed to achieve efficient formulation of non spore-forming bacterial biological control agents. In response to this, we propose a flow diagram made up of six steps including selection of growth parameters, checking of minimum shelf life, selection of protective additives, checking that the additives have no adverse effects, validation of the additive mix under field conditions and choosing whether to use additives as co-formulants or tank mix additives. This diagram is intended to provide guidance and decision-making criteria for the formulation of non spore-forming bacterial biological control agents against foliar pathogens. The diagram was then validated by designing an efficient formulation for a Gram-negative bacterium, Lysobacter capsici AZ78, to control grapevine downy mildew caused by Plasmopara viticola. A harvest of 10(10)L. capsici AZ78cellsml(-1) was obtained in a bench top fermenter. The viability of cells decreased by only one order of magnitude after one year of storage at 4°C. The use of a combination of corn steep liquor, lignosulfonate, and polyethyleneglycol in the formulation improved the survival of L. capsici AZ78 cells living on grapevine leaves under field conditions by one order of magnitude. Furthermore, the use of these additives also guaranteed a reduction of 71% in P. viticola attacks. In conclusion, this work presents a straightforward stepwise flow diagram to help researchers develop formulations for biological control agents that are easy to prepare, stable, not phytotoxic and able to protect the microorganims under field conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Nuevo acercamiento a la interacción del reactivo de Folin-Ciocalteu con azúcares durante la cuantificación de polifenoles totales

    Directory of Open Access Journals (Sweden)

    Óscar A. Muñoz-Bernal

    2017-01-01

    Full Text Available La mezcla de ácidos fosfomolíbdico y fosfotúngstico es el reactivo esencial de uno de los principales métodos para la cuantificación de compuestos polifenólicos en extractos vegetales conocido como método de reactivo de Folin-Ciocalteu (FC. Sin embargo, al igual que otros métodos espectrofotométricos puede ser inespecífico e interaccionar con otras moléculas como azúcares, presentes en los extractos vegetales, que pueden alterar los resultados encontrados. El objetivo del presente trabajo fue determinar el efecto de la glucosa, sacarosa, fructosa, xilosa, manosa, ramnosa y arabinosa sobre la cuantificación de compuestos polifenólicos mediante el método de FC. La fructosa y la xilosa fueron los azúcares con la mayor reactividad, mientras que la sacarosa, ramnosa, manosa y glucosa presentaron el menor efecto. La fructosa y la manosa tanto en las muestras de ácido gálico como en extractos de anís y chile jalapeño así como de especias tradicionales de la cocina mexicana (hoja santa y hoja de aguacate, reaccionaron diferente, ya que la fructosa incrementó la respuesta del método y consecuentemente sobreestimó el contenido de los compuestos polifenólicos y la manosa los subestimó. Los resultados obtenidos muestran que el contenido de azúcar en extractos puede interferir en la estimación de los compuestos polifenólicos, sobre todo si la concentración es muy alta o la fructosa está presente.

  6. Inmaculada Sánchez et Marta Díaz (dir., Doc 21 Panorama del reciente cine documental en España

    Directory of Open Access Journals (Sweden)

    Pietsie Feenstra

    2011-02-01

    Full Text Available Inmaculada Sánchez et Marta Díaz apportent un recueil d’articles très intéressants sur la richesse du documentaire espagnol actuel. A part des analyses précieuses sur quelques documentaires récents (En Construcción, 2000, Guerín ; El efecto Iguazú, 2002, Pere Joan Ventura et Georgina Cisquella ; La leyenda del tiempo, 2006, Isaki Lacuesta,…, l’ouvrage pose de nouvelles questions sur le processus de création et les moyens de financement ou la diffusion. Les deux axes permettent de mettre en l...

  7. De masonería, control y otras lealtades fraternales: el rescate de Porfirio Díaz por un hermano masón

    Directory of Open Access Journals (Sweden)

    Guillermo de los Reyes Heredia

    2015-01-01

    Full Text Available En este artículo se explora el papel que jugó Porfirio Díaz dentro de la masonería y su relación con dichainstitución. Se analiza una de las historias que comprueban que Díaz logró ciertos beneficios gracias a suafiliación masónica desde antes que fuera presidente de México. Esta historia narra la manera en que Díazlogró entrar de contrabando a México con la ayuda de un hermano masón en 1876, después de su breve exilioen Nuevo Orleans a bordo del buque de vapor, “City of Havana”. En un principio se pensaba que ésta erasimplemente una leyenda más del folklore que envuelve a la masonería. Sin embargo, dos testimonios, ambosde masones que iban en el mismo barco ratifican la historia que incluso el mismo historiador de la masoneríanorteamericana, William Deslow, catalogaba como un incidente, “no verificado.”Asimismo, se describe cómo Díaz promovió la unificación de las logias del rito escocés en unainstitución que se llamó La Gran Dieta Simbólica. La razón principal por la cual Díaz promovió talunificación, como se afirma en este artículo, fue para llevar a cabo su plan de pacificación nacional. Díazsabía que tenía que obtener el control de la masonería para evitar que ésta le causara problemas para lograr elorden y progreso que caracterizó a su gobierno. Por tal motivo, el dictador siempre vigiló que ni la masonería,ni cualquier otra institución que hubiera podido tener cierta influencia en la sociedad estuvieran fuera de sucontrol.

  8. Nuevo acercamiento a la interacción del reactivo de Folin-Ciocalteu con azúcares durante la cuantificación de polifenoles totales

    OpenAIRE

    Óscar A. Muñoz-Bernal; Gaspar A. Torres-Aguirre; José A. Núñez-Gastélum; Laura A. de la Rosa; Joaquín Rodrigo-García; J. Fernando Ayala-Zavala; Emilio Álvarez-Parrilla

    2017-01-01

    La mezcla de ácidos fosfomolíbdico y fosfotúngstico es el reactivo esencial de uno de los principales métodos para la cuantificación de compuestos polifenólicos en extractos vegetales conocido como método de reactivo de Folin-Ciocalteu (FC). Sin embargo, al igual que otros métodos espectrofotométricos puede ser inespecífico e interaccionar con otras moléculas como azúcares, presentes en los extractos vegetales, que pueden alterar los resultados encontrados. El objetivo del presente ...

  9. Environmental conditions of pilón de azúcar beach (guajira, colombia), inferedfrom the foraminifers population of a sediment simple

    OpenAIRE

    Ortiz Moreno, Martha Lucía; Acosta, Nelly

    2011-01-01

    Foraminifers are organisms, which due to their specific environmental requirements, are used as bio-indicators of marine environments. In this study we evaluated a sample of sediment from the “Pilón de Azúcar” beach (Guajira, Colombia), in order to deduce the physico-chemical conditions of such coastal environment, based on the group of 14 foraminifers found in it. We detect one hundred individuals belonging to 29 species,19 genus, 14 families, 8 super families, and 3 suborders: Rotaliina, Mi...

  10. Consumo de zumos de frutas y su aporte de azúcares en la población infanto-juvenil

    OpenAIRE

    Martínez Ferrán, María

    2017-01-01

    En el momento actual no existe consenso acerca de la idoneidad del consumo de zumos de frutas ya que tienen un alto contenido en azúcares libres que los hace equiparables, para algunos autores, a las bebidas azucaradas. Algunos estudios han encontrado asociación entre el consumo de zumos y la obesidad, la diabetes y la caries, aunque sin evidencia suficiente. Su consumo excesivo puede producir diarrea. Por otro lado, la ingesta de zumos se ha relacionado con una mayor calidad de la dieta, son...

  11. Estudio del comportamiento de algunos factores del Clima Organizacional en el Servicio de Urgencias de la Clínica Dr. Marcial Fallas Díaz

    OpenAIRE

    Domingo Mora, Lilliana

    2013-01-01

    Esta investigación partió del estudio del comportamiento de algunos factores del clima organizacional, tales como el liderazgo, la comunicación, la motivación y la participación, imperante en el servicio de urgencias de la Clínica Dr. Marcial Fallas Díaz, durante el primer semestre del año 2003. La inquietud para realizar dicha investigación surgió de la experiencia profesional y laboral obtenida por la investigadora en la citada Clínica, lo cual permitió identificar el problema, en su ...

  12. Reproducción de Micropterus salmoides (Pisces: Centrarchidae), en el embalse Gustavo Díaz Ordaz, Sinaloa, México

    OpenAIRE

    Rigoberto Beltrán Alvarez; Jesús Sánchez Palacios; Juan Pedro Ramírez Lozano; Adolfo-Armando Ortega Salas

    2013-01-01

    Micropterus salmoides es un pez de importancia para la pesca deportiva en la mayoría de los embalses de México y del mundo, por lo que en el embalse Gustavo Díaz Ordaz se realizó un estudio sobre aspectos reproductivos entre agosto 2008 y marzo 2011. Se recolectaron 938 organismos, a los cuales se les midió la longitud (Lt cm), peso (Pt g), se determinó el sexo, índice gonadosomático, factor de condición, fecundidad y talla de primera madurez. La longitud y peso de los ejemplares recolectados...

  13. Comportamiento superplástico de una aleación AZ61 procesada por extrusión en canal angular

    OpenAIRE

    M. Eddahbi; Ruano, O.A.

    2006-01-01

    This study is concerned with microstructural and mechanical characterization of the superplastic behaviour of a magnesium base AZ61 alloy processed by equal channel angular extrusion (ECA). Microscopic examinations showed that the microstructure after ECA was homogeneous and the grain size was about 5 mm. The extruded material showed better mechanical properties than the rolled material. The strain rate sensitivity exponent, at 250 ºC, was 0.5 at strain rates ranging from 10-4 to 5 . 10-4 s-1...

  14. ¿Cómo estimar la concentración de azúcar en gaseosas? Una introducción a la refractometría

    OpenAIRE

    Horacio Gibbs; Gabriel Pérez; Esteban Szigety; Javier Viau; María Alejandra Tintori Ferreira

    2014-01-01

    Con el propósito de promover practicas cotidianas que faciliten la construcción de nuevas maneras de ensenar y aprender ciencias es que presentamos una propuesta didáctica inscrita en un marco de educación científica escolar; cuyo punto de partida es una pregunta disparadora: .Como podrían estimar la concentración de azúcar en una bebida gaseosa?, una vez desarrollados los conceptos asociados a la reflexión-refracción de la luz en el aula. Se abordan en el aula de física conceptos de óptica g...

  15. Caracterización y evaluación del bagazo de caña de azúcar como biosorbente de hidrocarburos

    OpenAIRE

    Martinez Nodal, Pastora; Rodríguez Rico, Iván; Esperanza Pérez, Guillermo; Leiva Mas, Jorge

    2014-01-01

    En la caracterización del biosorbente (bagazo de caña de azúcar natural, BN) se determinaron diferentes parámetros físico-químicos: humedad, densidad aparente, densidad real, porosidad, flotabilidad, capacidad máxima de sorción y microscopia electrónica de barrido. Los resultados obtenidos permitieron definir la fracción de interés (+1 -2 mm), en base al rendimiento en el tamizado (41%), la homogeneidad de dicha fracción y su capacidad de sorción (2g diesel/g BN). Los resultados obtenidos en ...

  16. Producción de guarapo y bioetanol en siete variedades de caña de azúcar (Saccharum spp) COLPOSCTMEX.

    OpenAIRE

    López Vázquez, Pascual

    2013-01-01

    El presente estudio se realizó con el objetivo de evaluar la producción de guarapo y bioetanol en siete variedades de caña de azúcar COLPOSCTMEX, mediante la incorporación de tres niveles de fermento (Sacharomyces cerevisiae). Se determino la producción de guarapo por variedad, °brix, pH inicial, tiempo de fermentación, °brix y pH final de la fermentación, también se determino el grado alcohol y el rendimiento de alcohol por variedad. El jugo se extrajo de 20 tallos por variedad, la variedad ...

  17. Determinación de la vida de anaquel del chocolate de mesa sin azúcar en una película de polipropileno biorientado

    OpenAIRE

    Chica Cardona, Bibiana Andrea; Osorio Saldarriaga, Sandra Liliana

    2003-01-01

    El presente trabajo tuvo como objetivo determinar la durabilidad del chocolate de mesa sin azúcar, empacado en una película de polipropileno biorientado a diferentes condiciones de almacenamiento (dos temperaturas y dos humedades relativas), aplicando vida de anaquel acelerada al producto. Se determinaron los parámetros cinéticos (n, K, Ko y Ea) y por medio del modelo de Arrhenius se halló el tiempo de vida útil del chocolate. Paralelamente se obtuvieron las curvas de adsorción del choc...

  18. "TNOs are Cool": A survey of the trans-Neptunian region. XII. Thermal light curves of Haumea, 2003 VS2 and 2003 AZ84 with Herschel/PACS

    Science.gov (United States)

    Santos-Sanz, P.; Lellouch, E.; Groussin, O.; Lacerda, P.; Müller, T. G.; Ortiz, J. L.; Kiss, C.; Vilenius, E.; Stansberry, J.; Duffard, R.; Fornasier, S.; Jorda, L.; Thirouin, A.

    2017-08-01

    Context. Time series observations of the dwarf planet Haumea and the Plutinos 2003 VS2 and 2003 AZ84 with Herschel/PACS are presented in this work. Thermal emission of these trans-Neptunian objects (TNOs) were acquired as part of the "TNOs are Cool" Herschel Space Observatory key programme. Aims: We search for the thermal light curves at 100 and 160 μm of Haumea and 2003 AZ84, and at 70 and 160 μm for 2003 VS2 by means of photometric analysis of the PACS data. The goal of this work is to use these thermal light curves to obtain physical and thermophysical properties of these icy Solar System bodies. Methods: When a thermal light curve is detected, it is possible to derive or constrain the object thermal inertia, phase integral and/or surface roughness with thermophysical modeling. Results: Haumea's thermal light curve is clearly detected at 100 and 160 μm. The effect of the reported dark spot is apparent at 100 μm. Different thermophysical models were applied to these light curves, varying the thermophysical properties of the surface within and outside the spot. Although no model gives a perfect fit to the thermal observations, results imply an extremely low thermal inertia (0.73) for Haumea's surface. We note that the dark spot region appears to be only weakly different from the rest of the object, with modest changes in thermal inertia and/or phase integral. The thermal light curve of 2003 VS2 is not firmly detected at 70 μm and at 160 μm but a thermal inertia of (2 ± 0.5) MKS can be derived from these data. The thermal light curve of 2003 AZ84 is not firmly detected at 100 μm. We apply a thermophysical model to the mean thermal fluxes and to all the Herschel/PACS and Spitzer/MIPS thermal data of 2003 AZ84, obtaining a close to pole-on orientation as the most likely for this TNO. Conclusions: For the three TNOs, the thermal inertias derived from light curve analyses or from the thermophysical analysis of the mean thermal fluxes confirm the generally small

  19. Impacto de la grasa y del azúcar en las propiedades físicas y sensoriales de diferentes tipos de matrices alimentarias.

    OpenAIRE

    ARANCIBIA AGUILAR, CARLA ANDREA

    2013-01-01

    Las características de cada matriz alimentaria, la composición y estructura de los ingredientes, así como el efecto de las interacciones entre ellos, pueden modificar el impacto de la grasa y del azúcar en la estructura y en las propiedades físicas y sensoriales del alimento y en su aceptación por el consumidor. Para diseñar nuevos alimentos más saludables es necesario conocer y entender el efecto de estos componentes en las características del producto y las repercusiones...

  20. Modificaciones a un transportador apilador de sacos de azúcar // Modifications to a decker transporter of sugar sacks.

    Directory of Open Access Journals (Sweden)

    F. Aguilar Parés

    2000-07-01

    Full Text Available El transportador apilador que se construye actualmente en el país para satisfacer las demandas de los centrales azucarerosen el almacenamiento de sacos de azúcar, presenta dificultades técnicas que no permiten una buena comercialización delequipo.En el artículo se logra con la misma capacidad y longitud de transportación, así como con la misma solución técnica paravariar el ángulo de inclinación en el rango deseado, soluciones que permiten, disminuir el peso total del equipo en un 20%., se cambia la solución estructural y se disminuye el espesor de los perfiles, se eliminan los problemas de estabilidad, secambia la ubicación del sistema motriz de la zona de descarga a un punto cercano a la zona de carga, etc.Aprovechando la instalación óleo-hidráulica para cambiar el ángulo de inclinación, se le añade un circuito que permitefácilmente cambiar el sentido de giro de la tambora motriz.Se presenta también el procedimiento para comprobar la potencia del motor. De dicho procedimiento se explica como hacerel gráfico de carga, el cual limita la capacidad de carga en función del ángulo de inclinación.Palabras claves: transportador de banda, estructura, estabilidad, accionamiento óleo - hidráulico._____________________________________________________________________Abstract:The decker transporter that is built at the moment in the country to satisfy the demands of the sugar power stations in thestorage of sugar sacks, presents technical difficulties that do not allow a good commercialization of the equipment.In the developed work it is achieved that with the same capacity and transportation longitude, as well as with the sametechnical solution to vary the angle of inclination in the wanted range, diminish the total weight of the equipment in 20%,with the employment of a professional program, the structural solution is changed and the thickness of the profiles isdecreased, eliminate the problems of stability. The location of the

  1. Tratamiento antimicrobiano en la meningoencefalitis, Hospital Militar Central "Dr. Luis Díaz Soto", 2004-2011

    Directory of Open Access Journals (Sweden)

    María del Carmen Jiménez Martínez

    Full Text Available Introducción: las meningoencefalitis constituyen un grupo de gran importancia dentro de las enfermedades infecciosas, en las cuales la introducción de los antibióticos hizo posible que fuese curable, pero la morbilidad y la mortalidad de esta enfermedad continúan siendo inaceptablemente altas. Objetivo: identificar la terapia antimicrobiana usada en las meningoencefalitis. Métodos: estudio descriptivo, observacional y retrospectivo. Se estudiaron 150 pacientes con diagnóstico de meningoencefalitis viral o meningoencefalitis bacteriana confirmada por cuadro clínico, estudio citoquímico del líquido cefalorraquídeo o identificación del agente etiológico. Todos se atendieron en el período comprendido entre los años 2004 y primer semestre del 2011, en los servicios de Medicina y Pediatría del Hospital Militar Central "Dr. Luis Díaz Soto". Se empleó el diseño de un estudio de utilización de medicamentos que hace uso de la indicación-prescripción y el esquema terapéutico para este tipo de paciente. Resultados: se utilizó terapia antimicrobiana en el 18,67 % de pacientes con meningoencefalitis viral (23,93 % de 117 y el 22 % con bacteriana (100 % de 33 casos. Las antibioticoterapias más usadas fueron la ceftriaxona (como único antibiótico en la meningoencefalitis viral, y asociada (ceftriaxona más vancomicina en la meningoencefalitis bacteriana. El patógeno más aislado (Streptococcus pneumoniae fue tratado en la mayoría de los casos con ceftriaxona más vancomicina. La generalidad de los tratamientos para la meningoencefalitis bacteriana duró menos de 21 días. Conclusiones: se evidenció el uso de terapia antimicrobiana en pacientes con meningoencefalitis viral y la coincidencia entre la terapia empírica y la específica en la meningoencefalitis bacteriana.

  2. VizieR Online Data Catalog: AzTEC survey of the SHADES fields. II. (Michalowski+, 2012)

    Science.gov (United States)

    Michalowski, M. J.; Dunlop, J. S.; Ivison, R. J.; Cirasuolo, M.; Caputi, K. I.; Aretxaga, I.; Arumugam, V.; Austermann, J. E.; Chapin, E. L.; Chapman, S. C.; Coppin, K. E. K.; Egami, E.; Hughes, D. H.; Ibar, E.; Mortier, A. M. J.; Schael, A. M.; Scott, K. S.; Smail, I.; Targett, T. A.; Wagg, J.; Wilson, G. W.; Xu, L.; Yun, M.

    2013-04-01

    We utilized the JCMT/AzTEC 1.1mm maps and catalogues from Austermann et al. (2010, Cat. J/MNRAS/401/160). These data cover 0.7deg2 to an rms depth of 0.9-1.7mJy/beam. We selected all 148 sources presented by Austermann et al. (2010, Cat. J/MNRAS/401/160) with signal-to-noise ratios (S/Ns) > 3.5, and adopted the statistically deboosted 1.1mm flux densities. The VLA 1.4GHz and GMRT 0.61GHz radio data were taken from Ivison et al. (2005MNRAS.364.1025I, 2007, Cat. J/MNRAS/380/199) and Ibar et al. (2009, Cat. J/MNRAS/397/281, 2010MNRAS.401L..53I), respectively. The mid-IR Spitzer data in the Lockman Hole East field are from programmes PID 81 (PI: G. Rieke) and PID 50249 (PI: E. Egami), described in Egami et al. (2004ApJS..154..130E) and Dye et al. (2008MNRAS.386.1107D), whereas in the UDS field the mid-IR data are from the Spitzer Public Legacy Survey of the UKIDSS UDS (PI: J. Dunlop, http://ssc.spitzer.caltech.edu/spitzermission/observingprograms/ legacy/spuds/) described in Caputi et al. (2011MNRAS.413..162C). The optical data in both fields were obtained with Subaru/SuprimeCam, as described in Dye et al. (2006MNRAS.372.1227D) and Furusawa et al. (2008, Cat. J/ApJS/176/1). The near-IR data in both fields are provided by the UKIRT Infrared Deep Sky Survey (UKIDSS; Lawrence et al. 2007, Cat. II/314) with the SXDF/UDS field benefitting from the ultradeep J, H, K coverage provided by the UDS (e.g. Cirasuolo et al. 2010MNRAS.401.1166C), while the Lockman Hole East field is part of the somewhat shallower UKIDSS DXS (Warren et al., 2007MNRAS.375..213W). (5 data files).

  3. Structural and corrosion characterization of hydroxyapatite/zirconium nitride-coated AZ91 magnesium alloy by ion beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Kiahosseini, Seyed Rahim, E-mail: rkiahoseyni@yahoo.com [Young Researchers and Elite Club, Damghan Branch, Islamic Azad University, Damghan (Iran, Islamic Republic of); Afshar, Abdollah [Department of Material Science and Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Mojtahedzadeh Larijani, Majid [Radiation Applications Research School, Nuclear Science and Technology Research Institute, Tehran (Iran, Islamic Republic of); Yousefpour, Mardali [Faculty of Materials and Metallurgical Engineering, Semnan University, Semnan, 35131-19111 (Iran, Islamic Republic of)

    2017-04-15

    Highlights: • The thickness of HA coatings increase by ion beam sputtering time. • The residual strain in HA structure decrease by deposition time increment. • Crystallite size of HA coatings increase by deposition time increment. • The best corrosion resistance occurs at intermediate deposition time. - Abstract: The adhesion of hydroxyapatite (HA) as a coating for the AZ91 magnesium alloy substrate can be improved by using the sputtering method and an intermediate layer, such as ZrN. In this study, HA coatings were applied on ZrN intermediate layers at a temperature of 300 °C for 180, 240, 300, 360, and 420 min by ion beam sputtering. A profilometer device was used to study the HA coating thickness, which changed from 2 μm for the 180-min deposition to 4.7 μm for 420-min deposition. The grazing incidence X-ray diffraction analysis method and the Williamson–Hall analysis were used for structural investigation. As the deposition time increased, the crystalline size increased from 50 nm to 690 nm. However, given sufficient time for stress relief on the coating structure, the lattice strain values were close to zero. Energy-dispersive X-ray spectroscopy results showed that the Ca/P ratio ranged from 1.73 to 1.81. The external indentation method was used to evaluate the coating adhesion to the substrate. The slope of curve for applied force changes versus the radius of cracks in the coating (dP/dr) varied in the range of 0.2–0.07 by the deposition time, indicating that the adhesion increased with the increase in coating thickness. The potentiodynamic polarization technique was used to study the corrosion behavior. With increasing deposition time, the corrosion potential of samples did not show a significant change, and the corrosion potential of all samples (coated and uncoated substrates) was more positive than approximately 55 mV. When the deposition time increased to 360 min, the corrosion current density decreased from 5.5 μA/cm{sup 2} to 0.33

  4. Estudio toxicológico de un producto derivado de la caña de azúcar

    Directory of Open Access Journals (Sweden)

    Carmen Luisa García Rivero

    1997-08-01

    Full Text Available Se presentan los resultados obtenidos en la evaluación toxicológica preclínica de un principio activo formulado en crema con propiedades cicatrizantes y antifúngicas a partir de un producto natural derivado de la caña de azúcar, al cual se le determinó su inocuidad en animales de experimentación mediante la estimación de la dosis letal media en conejos F1 y ratas albinas Wistar, utilizando niveles de dosis elevados. También se estudió el potencial irritante sobre la piel, mucosa ocular, vaginal y rectal, así como su potencial como agente sensibilizante. De forma general los síntomas tóxicos observados no fueron significativos y desaparecieron en un período corto, no se presentó mortalidad y se comprobó la ausencia de efectos irritantes sobre la piel y mucosas evaluadas. Se demostró que el producto no es un agente sensibilizante. Los resultados obtenidos en el estudio realizado permiten clasificar al producto de una baja toxicidad.This paper reports on the results obtained from the preclinical toxicity assessment of an active ingredient formulated as a cream having healing and antifungal properties which was obtained from a natural product derived from sugar cane. The drug testing included the determination of its safety in experimental animals by the estimation of the mean lethal dose in rabbits F1 and albino Wistar rats using high dose levels. The potential irritancy on the skin, ophthalmic, vaginal and rectal mucosa was also studied, as well as the potential as a sensibilizing agent. Overall, the toxic symptoms observed were found to be no significant and they dissapeared within a short period of time. There was no mortality and the absence of irritant effects on the skin and mucosa was evidenced in the evaluation. It was proved that this product is not a sensibilizing agent. Results obtained from the study carried out allow to classify this product as having low toxicity levels.

  5. Evaluación de la influencia del contenido de borras y azúcares reductores del vino base de uva italia (Vitis vinífera L.) para la obtención del pisco mosto verde

    OpenAIRE

    Chaparro Montoya, Efren Eugenio

    2015-01-01

    El presente trabajo de investigación tuvo como finalidad evaluar la influencia del contenido de borras y azúcares reductores del vino base de uva Italia (Vitis vinífera L.) para la obtención de pisco Mosto Verde. La muestra de uva Italia fue de Magollo -Tacna, la fermentación del mosto se inició con una acidez tartárica de 7,0 g/L; 14,0 grados Baumé (239 g/L de azúcares reductores, considerado como 100 % de azúcares reductores) y un pH=3,6. Se utilizó un diseño central compuesto con tres repe...

  6. Definitions A-Z

    Science.gov (United States)

    ... numbness, tingling or weakness of the leg called “sciatica.” Also known as a slipped or ruptured disc, ... above the coccyx and below the lumbar spine. sciatica: Pain, numbness, tingling in the distribution of the ...

  7. Maricopa County, AZ, USA

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — The Floodplain Mapping study deliverables depict and quantify the flood risks for the study area. The primary risk classifications used are the...

  8. ORTHOIMAGERY, MARICOPA COUNTY, AZ

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — Digital orthographic imagery datasets contain georeferenced images of the Earth's surface, collected by a sensor in which object displacement has been removed for...

  9. Definitions A-Z

    Science.gov (United States)

    ... The intervertebral disc is a combination of strong connective tissues which hold one vertebra to the next, ... A diagnostic imaging test. MRI clearly images soft tissues such as the intervertebral disc ... back of the spinal canal and a bone graft is inserted in the invertebral space also through ...

  10. Effect of Casting Parameters on the Microstructural and Mechanical Behavior of Magnesium AZ31-B Alloy Strips Cast on a Single Belt Casting Simulator

    Directory of Open Access Journals (Sweden)

    Ahmad Changizi

    2014-01-01

    Full Text Available Strips of magnesium alloy AZ31-B were cast on a simulator of a horizontal single belt caster incorporating a moving mold system. Mixtures of CO2 and sulfur hexafluoride (SF6 gases were used as protective atmosphere during melting and casting. The castability of the AZ31-B strips was investigated for a smooth, low carbon steel substrate, and six copper substrates with various textures and roughnesses. Graphite powder was used to coat the substrates. The correlation between strip thickness and heat flux was investigated. It was found that the heat flux from the forming strip to the copper substrate was higher than that to the steel substrate, while coated substrates registered lower heat fluxes than uncoated substrates. The highest heat flux from the strip was recorded for casting on macrotextured copper substrates with 0.15 mm grooves. As the thickness of the strip decreased, the net heat flux decreased. As the heat flux increased, the grain sizes of the strips were reduced, and the SDAS decreased. The mechanical properties were improved when the heat flux increased. The black layers which formed on the strips’ surfaces were analyzed and identified as nanoscale MgO particles. Nano-Scale particles act as light traps and appeared black.

  11. Modelo semifísico de base fenomenológica de un evaporador de jugo de caña de azúcar tipo Roberts

    Directory of Open Access Journals (Sweden)

    Santiago López

    2014-07-01

    Full Text Available En el presente trabajo se expone el desarrollo de un Modelo semifísico de base fenomenológica (MSBF para un evaporador de jugo de caña de azúcar tipo Roberts, considerando el fenómeno de ensuciamiento, los diferentes regímenes de evaporación en el tubo y un cambio de presión interno producido por el acople del ducto de salida de vapor vegetal con un condensador barométrico. El modelo describe el comportamiento de la concentración de sacarosa (grados Brix en el jugo de caña de azúcar, con variaciones en el vapor suministrado en la caldera y el flujo de agua de enfriamiento entrante al condensador. También informa sobre la presión en el compartimento superior del evaporador, lo cual ante una caída de presión la tasa de evaporación aumenta debido a las propiedades termodinámicas del fluido. Sin embargo, esta presión en el condensador es una dinámica inherentemente inestable, ya que su comportamiento es inestable ante pequeños cambios en las otras variables. Esto sugiere que esta dinámica debe de ser controlada antes que cualquier otra. La simulación numérica valida de forma cualitativa el modelo obtenido.

  12. Preparation and characterization of HA microflowers coating on AZ31 magnesium alloy by micro-arc oxidation and a solution treatment

    Energy Technology Data Exchange (ETDEWEB)

    Tang Hui [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Yu Dezhen [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Luo Yan [Department of Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Wang Fuping, E-mail: hitth001@yahoo.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer Hydroxyapatite microflowers coating is fabricated by micro-arc oxidation and a solution treatment on AZ31 magnesium alloy. Black-Right-Pointing-Pointer The corrosion resistance of the magnesium alloy has been enhanced by micro-arc oxidation and solution treatment. Black-Right-Pointing-Pointer The coating fabricated by micro-arc oxidation and solution treatment exhibits a high ability to form apatite. - Abstract: Magnesium and its alloys are potential biodegradable implant materials due to their attractive biological properties. But the use of magnesium is still hampered by its poor corrosion resistance in physiological fluids. In this work, hydroxyapatite microflowers coating is fabricated by micro-arc oxidation and a solution treatment on AZ31 magnesium alloy. The microstructure and composition are analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The potentiodynamic polarization and electrochemical impedance spectroscopy are studied in simulated body fluid (SBF) solution, and the apatite-forming ability is studied also. The results show that the corrosion resistance of the magnesium alloy has been enhanced by MAO coating. And the solution treatment can improve the corrosion resistance of the MAO sample, by forming a barrier layer on the surface of the MAO coating, and by penetrating into the outer layer of the MAO film, sealing the micropores and micro-cracks existed in the MAO coating. In addition, the MAO-ST coating also exhibits a high ability to form apatite.

  13. La persecución del lulismo en la catedral de Mallorca durante el episcopado de Juan Díaz de la Guerra 1772-1777

    Directory of Open Access Journals (Sweden)

    García Pérez, Francisco José

    2014-12-01

    Full Text Available This article examines the repression exercised by the Bishop of Mallorca, don Juan Díaz de la Guerra, against Llull worship at the Cathedral of Mallorca. Facing members of the chapter, the Bishop initiated an iconoclastic persecution inside the Cathedral building. In addition, he forbade any neophyte could be baptized with the name of Ramon. This degenerated into a deep schism in the Mallorcan ecclesiastical elite and affected, inevitably, all the churches and convents of Mallorca.El presente artículo analiza la represión ejercida por el obispo de Mallorca, don Juan Díaz de la Guerra, contra el culto luliano en la Catedral de Mallorca. Enfrentándose a los miembros del Cabildo, el obispo inició una persecución iconoclasta dentro del edificio catedralicio. Además, prohibió que ningún neófito pudiese ser bautizado con el nombre de Ramón. Esto degeneró en un profundo cisma en la élite eclesiástica mallorquina y afectó, inevitablemente, a todas las iglesias y conventos de Mallorca.

  14. Sparse feature selection identifies H2A.Z as a novel, pattern-specific biomarker for asymmetrically self-renewing distributed stem cells

    Directory of Open Access Journals (Sweden)

    Yang Hoon Huh

    2015-03-01

    Full Text Available There is a long-standing unmet clinical need for biomarkers with high specificity for distributed stem cells (DSCs in tissues, or for use in diagnostic and therapeutic cell preparations (e.g., bone marrow. Although DSCs are essential for tissue maintenance and repair, accurate determination of their numbers for medical applications has been problematic. Previous searches for biomarkers expressed specifically in DSCs were hampered by difficulty obtaining pure DSCs and by the challenges in mining complex molecular expression data. To identify such useful and specific DSC biomarkers, we combined a novel sparse feature selection method with combinatorial molecular expression data focused on asymmetric self-renewal, a conspicuous property of DSCs. The analysis identified reduced expression of the histone H2A variant H2A.Z as a superior molecular discriminator for DSC asymmetric self-renewal. Subsequent molecular expression studies showed H2A.Z to be a novel “pattern-specific biomarker” for asymmetrically self-renewing cells, with sufficient specificity to count asymmetrically self-renewing DSCs in vitro and potentially in situ.

  15. Influence of mixed organosilane coatings with variable RGD surface densities on the adhesion and proliferation of human osteosarcoma Saos-2 cells to magnesium alloy AZ31

    Directory of Open Access Journals (Sweden)

    Xiaoxi Yang

    2017-03-01

    Full Text Available In the last decade, the use of magnesium and its alloys as biodegradable implant materials has become increasingly accepted. However, surface modification of these materials to control the degradation rate in the early stages of healing and improve their biocompatibility is crucial to the successful implementation of magnesium alloy implants in medicine. Cell adhesion and proliferation at the implant surface is a vital factor for successful integration of a biomaterial within the body. Cells accomplish this task by binding to ligands such as the arginine-glycine-aspartic acid peptide sequence (RGD commonly found on adhesive proteins present in the extracellular matrix. In this paper, we report a biomimetic surface modification strategy involving deposition of a mixed organosilane layer on Mg AZ31 followed by covalent immobilization of RGD peptides through a heterobifunctional cross-linker molecule. Our results indicate that with optimized deposition conditions uniform organosilane coatings were successfully deposited on the Mg AZ31 substrate. Furthermore, we have demonstrated that the surface density of immobilized RGD can be varied by depositing organosilane layers from solutions containing two different organosilanes in specified ratios. Increases in cell adhesion and cell proliferation were observed on the surface modified substrates.

  16. Rendimiento de morteros producidos con la incorporación de ceniza de bagazo de caña de azúcar

    Directory of Open Access Journals (Sweden)

    Pamela Camargo Macedo

    2014-08-01

    Full Text Available Este trabajo presenta la factibilidad técnica de utilización de cenizas resultantes del proceso de la quema de bagazo de caña de azúcar, para la generación de energía como adición mineral en morteros. Se realizaron ensayos de caracterización química y la difracción de rayos x en las cenizas del bagazo de la caña de azúcar (CBC. Un estudio de molienda del material fue realizado, junto con la composición de los morteros que contienen los niveles de CBC de 3%, 5%, 8% y 10% en peso como sustitución parcial del agregado fino. A través de la resistencia a la compresión y tracción por compresión diametral fueron analizadas sus propiedades mecánicas. También se han encontrado algunas propiedades relacionadas con la durabilidad del material, tales como el encogimiento, absorción y acelerada reactividad. El trabajo se realizó con la actividad puzolánica de la CBC. Sin embargo, los resultados indican que es posible utilizar el CBC como sustitución parcial de agregado fino, en la producción de mortero.

  17. Characterization of a high strength Al-alloy interlayer for mechanical bonding of Ti to AZ31 and associated tri-layered clad

    Directory of Open Access Journals (Sweden)

    Yasser Fouad

    2014-06-01

    Full Text Available The Al 6081 alloy is proposed as a favorable interlayer alloy with satisfactory deformability characteristics; high strength; least reactivity and melting temperature for high temperature joining of pure Ti and AZ 31. Titanium and Magnesium sheets with Al–0.81 Mg–0.9 Si alloy interlayer plate were joined by cold-roll bonding and subsequent annealing treatment. The maximum strength after annealing at 550 °C is due to the combined effect of the precipitation strengthening of Al–Mg–Zn interlayer and static strain aging. The most pronounced increase in the Vickers microhardness (from 49.2 to 74.5 Hv was observed in the Al 6081 interface with AZ31 and Ti, thus indicating Al 6081 as a sound bonding interlayer with a lower melting temperature, initial excellent deformability and high strength after joining. With the increase in heat-treatment temperature, the tensile strength increased initially up to 550 °C and then decreased with the increase in annealing temperature to levels above 550 °C. The threshold deformation is about 44% of the total rolling reduction in a single rolling pass. The highest mechanical properties were 35 MPa in the composite – which was obtained by 550 °C/2 h annealing treatment.

  18. Índice normalizado de vegetación en caña de azúcar en la Huasteca Potosina

    Directory of Open Access Journals (Sweden)

    N. Aguilar

    2010-01-01

    Full Text Available La aplicación de los Sistemas deInformación Geográfica (SIG y las técnicas de Percepción Remota (PR han sido ampliamente investigadas como método para identificar y evaluar el cultivo de caña de azúcar. El objetivo del presente estudio fue estimar y mapear el área bajo el cultivo de caña y evaluar su estado de salud mediante el algoritmo NDVI (Índice Normalizado de Vegetación, derivado del procesamiento e interpretación de imágenes Landsat-7/ETM+. Los resultados mostraron un NDVI en el rango de -0.3 a 0.3, que ejemplifica un estado de vigor del cultivo de caña de pobre a moderado debido al estrés. Solamente el 7.98% del total se considera en niveles aceptables. El Índice Normalizado de Vegetación fue un método útil en la identificación y evaluación del cultivo de caña. La agroindustria de la caña de azúcar de la Huasteca puede incrementar su productividad en el futuro mediante el uso de nuevos sistemas de manejo del cultivo y el ambiente para optimizar recursos e incrementar ganancias.

  19. Effect of the pretreatment of silicone penetrant on the performance of the chromium-free chemfilm coated on AZ91D magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Shiuan-Ho, E-mail: 1802186169@qq.com [College of Electronic Information and Mechatronic Engineering, Zhaoqing University, Zhaoqing Road, Duanzhou District, Zhaoqing, Guangdong, 526061 (China); Niu, Liyuan [Department of Material Engineer, Zhejiang Industry & Trade Vocational Colledge, WenZhou, 325000 (China); Su, Yichang [Department of Material Engineer, Zhejiang Industry & Trade Vocational Colledge, WenZhou, 325000 (China); College of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun, 130025 (China); Wang, Wenquan [College of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun, 130025 (China); Tong, Xian [Department of Material Engineer, Zhejiang Industry & Trade Vocational Colledge, WenZhou, 325000 (China); Li, Guangyu [College of Materials Science and Engineering, Jilin University, Nanling Campus, Changchun, 130025 (China)

    2016-03-01

    This paper reported a new pretreatment of silicone penetrant for forming the chromium-free chemfilm (chemical conversion coating) on the surface of an AZ91D magnesium (Mg) alloy. Through applying micro current on the pretreatment solution, an uniform mask membrane was created on the surface of a Mg alloy. By using X-ray diffraction (XRD), scanning electron microscope (SEM), and Energy Dispersive Spectrometer (EDS) analyses, the chromium-free chemfilm on a Mg alloy was examined to analyze the performance during initial, middle, and final deposition periods. As a result, the pretreatment of silicone penetrant can effectively prevent the chemfilm from cracking, improve the anticorrosion ability and nucleation rate of the chromium-free chemfilm on a Mg alloy, and make the surface crystallization transform a long strip into short axis shape. - Highlights: • An AZ91D Mg alloy was pretreated by using silicone penetrant. • Surface crystallization of the chemfilm on a silicone-pretreated Mg alloy is smooth. • The pretreatment of silicone penetrant for a Mg alloy enhanced the anticorrosion ability.

  20. Descripción de un proceso tecnificado para la elaboración de piloncillo a partir de caña de azúcar

    Directory of Open Access Journals (Sweden)

    Josué R. Solís Pacheco

    2006-01-01

    Full Text Available Este trabajo hace referencia a un proceso tecnificado para la elaboración de piloncillo a partir del jugo de caña de azúcar, conservando las características del proceso tradicional, con la finalidad de mantener la identidad del producto, y considerarlo como un alimento natural mínimamente procesado. Se ha desarrollado un proceso semi-continuo para la elaboración de piloncillo, sin que se vean afectadas sus características originales y con calidad destinada para el consumo humano. El proceso consiste en tres etapas principales: una etapa de extracción de jugo de caña, la segunda etapa una clarificación y concentración del jugo y como última etapa el moldeo del piloncillo. La dureza del piloncillo es una de las características más importante que describe la calidad del producto y está ligada directamente a la concentración de Azúcares Reductores Directos (ARD durante el proceso de elaboración. La aplicación de temperaturas muy altas durante tiempos prolongados, puede generar aumento considerable en las concentraciones de ARD. La estrecha relación entre la concentración de ARD y la dureza del piloncillo indica que mientras más baja es la concentración de ARD, más firme es su consistencia

  1. Effects of macroH2A and H2A.Z on nucleosome structure and dynamics as elucidated by molecular dynamics simulations

    CERN Document Server

    Bowerman, Samuel

    2015-01-01

    Eukaryotes tune the transcriptional activity of their genome by altering the nucleosome core particle through multiple chemical processes. In particular, replacement of the canonical H2A histone with the variants macroH2A and H2A.Z has been shown to affect DNA accessibility and nucleosome stability; however, the processes by which this occurs remain poorly understood. Here, we elucidate the molecular mechanisms of these variants with an extensive molecular dynamics study of the canonical nucleosome along with three variant-containing structures: H2A.Z, macroH2A, and an H2A mutant with macroH2A-like L1 loops. Simulation results show that variant L1 loops play a pivotal role in stabilizing DNA binding to the octamer through direct interactions, core structural rearrangements, and altered allosteric networks in the nucleosome. All variants influence dynamics; however, macroH2A-like systems have the largest effect on energetics. In addition, we provide a comprehensive analysis of allosteric networks in the nucleo...

  2. Alternativas de modificación del método de somogyi-nelson para la determinación de azúcares reductores a partir de sus posibilidades químicas

    OpenAIRE

    González Blair, Gloria Helena; Castellanos Domínguez, Óscar Fernando

    2010-01-01

    En el presente artículo se plantea modificar el método de Somogyi-Nelson para la determinación de azúcares reductores, considerando que el arsenato de sodio, uno de sus constituyentes, es una sustancia tóxica tendiente a desparecer del mercado. Se explican los principios químicos que utiliza el método de Somogyi - Nelson para la determinación de azúcares reductores, tomando como referencia los protocolos propuestos por Hawk et al. (1954), Collmer et al. (1988), Castellanos (1995) y el Departa...

  3. Azúcar y Revolución: El sector azucarero de la economía cubana durante los primeros doce años de la Revolución (1959-1970)

    OpenAIRE

    Santamaría García, Antonio

    1994-01-01

    Editada en la Universidad Carlos III «Azúcar y Revolución» estudia el comportamiento del sector azucarero durante los primeros doce años de la Revolución cubana; desde 1959, hasta 1ª denominada Zafra de los Diez Millones (1970). Las relaciones entre azúcar y Revolución atraviesan por varias fases que, en general, pueden sintetizarse en dos. Entre 1959 y 1970, los líderes revolucionarios intentarán implementar una política de industrialización y diversificación económica marcadamente antiaz...

  4. Análisis de la percepción que sobre el consumo de azúcar y sus sustitutos, tienen los habitantes de Santiago de Cali y planteamiento de propuestas para el cambio de actitudes

    OpenAIRE

    Cárdenas Sánchez, María Lorena

    2013-01-01

    El propósito de este estudio es investigar la percepción actual de los habitantes de Santiago de Cali con respecto al consumo de azúcar y elaborar propuestas para el cambio de actitudes. Para efectos del estudio, se han incluido en la muestra, hombres y mujeres, con entre las edades de 20 a 59 años, de los estratos 3, 4, 5 y 6 que toman la decisión de compra de los productos que se evaluaron en este proyecto (azúcar y edulcorantes sustitutos). El desarrollo de este trabajo permitió estable...

  5. Efecto de la fertilización fosfatada con cachaza sobre la actividad microbiana del suelo y la absorción de fósforo en caña de azúcar (Saccharum spp.)

    OpenAIRE

    Saucedo Castillo, Orlando; Prado,Renato de Mello; Castellanos González, Leónides; Ely, Nahas; Silva Campos, Cid Naudi; Silva, Gilmara Pereira da [UNESP; Assis, Luis Carlos [UNESP

    2015-01-01

    El objetivo del trabajo fue evaluar el efecto de diferentes dosis de fertilizante fosfatado con la adición de cachaza sobre la actividad microbiana del suelo, y el contenido de fósforo en el suelo y en plantas de caña de azúcar. El experimento se condujo en condi- ciones de invernadero en Jaboticabal Brasil en 2013, usándose plántulas de caña de azúcar (variedad "CTC 05"). Las unidades experimentales estuvieron constituidas por macet...

  6. Pathogen and nutrient pulsing and attenuation in "accidental" urban wetland networks along the Salt River in Phoenix, AZ

    Science.gov (United States)

    Palta, M. M.; Grimm, N. B.

    2013-12-01

    Increases in available nutrients and bacteria in urban streams are at the forefront of research concerns within the ecological and medical communities, and both pollutants are expected to become more problematic under projected changes in climate. Season, discharge, instream conditions (oxygen, water velocity), and weather conditions (antecedent moisture) all may influence loading rates to and the retention capabilities of wetlands fed by urban runoff and storm flow. The aim of this research was to examine the effect of these variables on nutrient (nitrogen, phosphorus) and Escherichia coli (E. coli) loading and attenuation along flow paths in urban wetland networks along the Salt River in Phoenix, AZ. Samples were collected for one year along flowpaths through wetlands that formed below six perennially flowing outfalls. Collection took place monthly during baseflow (dry season) conditions, and before and immediately following storm events, in the summer monsoon and winter rainy seasons. Water quality was assessed at the following points: immediately downstream of the outfall, mid-wetland, and downstream of the wetland. For determination of E. coli counts, samples were plated on coliform-selective media (Chromocult) and incubated for 24 hours. Plates were then used to enumerate E. coli. For determination of nutrient concentrations, samples were filtered and frozen until they could be analyzed by ion chromatography and automated wet chemistry. During both summer and winter, total discharge into the wetlands increased during storm events. Concentrations of PO43+, NH4+, and E. coli were significantly higher following storm events than during baseflow conditions, and post-storm peaks in concentration ('pulses') were higher during the summer monsoon than in winter storms. Pulses of pollutants during storms were highest when preceded by hot, dry conditions. NO3- was high in both base and stormflow. E. coli counts and nutrient concentrations dropped along flowpaths

  7. Métodos indirectos para estimar masa radical en caña de azúcar, variedad CC 8592

    Directory of Open Access Journals (Sweden)

    Mejia M. S.

    2004-12-01

    Full Text Available En casas de malla (31°C, 58% HR se evaluaron tres metodologías no destructivas (capacitancia eléctrica, amperaje, resistencia eléctrica para estimar la masa radical en caña de azúcar variedad CC 8592. El material vegetal se sometió a diferentes niveles de humedad en el sustrato. Se utilizó un diseño completamente al azar, con 13 repeticiones; las plantas se sembraron en materos plásticos (3 kg con cachaza - carbonilla (3:1; 24 horas antes de las mediciones se saturó el sustrato con agua. Mediante regresión lineal se obtuvieron las siguientes ecuaciones que relacionaron capacitancia (X con masa radical fresca (Y: Y = 6.841X - 49.623 (R2 = 0.829, P < 0.001, y con la masa radical seca: Y = 0.9546X - 7.4649 (R2 = 0.545, P < 0.001. La relación del amperaje con la masa radical fresca fue: Y = 0.4138X - 48.194 (R2 = 0.850, P <0.001 y con la masa radical seca: Y = 0.0577X - 7.2575 (R2 = 0.559, P <0.001; este método presentó mayor confiabilidad que el del capacitómetro. El método de la resistencia eléctrica no presentó resultados confiables. ABSTRACT Indirect methods to estimate the root biomass in sugar cane, cultivar CC 8592. In greenhouses (31°C, 58% RH three nondestructive methods were evaluated (electrical capacitance, amperage electrical resistance to estimate the root biomass. There was used a completely randomized design, with 4 treatments and 13 replications, the plants were seeded in plastic pots (3 kg using a mix of cachaza and fine coal (3:1; 24 hours before the measurements the substrate was saturated with water. By means of linear regression were obtained the following equations that relate fresh root (Y and capacitance (X: Y = 6.841X - 49.623 (R2 = 0.829, P < 0.001; and dry root biomass to capacitance: Y = 0.9546X - 7.4649 (R2 = 0.545, P < 0.001. The relation of fresh root biomass and amperage was Y = 0.4138X - 48.194 (R2 = 0.850, P < 0.001 and dry root biomass with amperage, Y = 0.0577X - 7.2575 (R2 = 0.559, P

  8. "Visiones de un vencido" "Joseph Domingo Díaz testigo ocular de la Revolución de Venezuela" (1810 - 1824

    Directory of Open Access Journals (Sweden)

    Francisco Mangano-Molero

    2010-01-01

    Full Text Available La historiografía tradicional venezolana ha justificado los movimientos revolucionarios separatistas nacidos a partir de 1808, presentando los testimonios de los ganadores de la disputa, convirtiéndolos en los argumentos del vencedor y bautizando a los protagonistas como los padres de la patria y creadores de la actual nación venezolana. Pero este mismo proceso de debilitamiento y posterior ruptura de trescientos años de dominación, que generó la actual Venezuela, no debe estudiarse solo desde la mirada del vencedor. El entendimiento de las representaciones del vencido y de la destrucción del dominante, se debe organizar partiendo de las experiencias propias de los actores sociales que no triunfaron en la contienda, partiendo de esas experiencia se deben estructurar discursos apegados a la realidad, donde las interpretaciones responden verdaderamente al estudio de las fuentes conjugados con los aportes teóricos. Dentro de este marco de caracterización histórica, presentamos la visión de un vencido Joseph Domingo Díaz, el cual representó fielmente los lineamientos de la corona por haber sido "Testigo ocular de la revolución de Venezuela en casi todos sus acontecimientos" (Díaz, 1961; 43, el enfoque dado por este actor no leal a las convicciones patriotas, nos indica otra forma de construir el conocimiento histórico e interpretar los hechos, al mostrarnos las motivaciones no patrióticas de los Libertadores y constituir un valuarte de fidelidad para con su Majestad. Tomando en cuentas estas consideraciones se pretende estudiar basado en la estructura metodológica de las representaciones colectivas, las diferentes formas de ver el conflicto revolucionario emancipador desde 1810 hasta 1824, al tener como fuente principal los escritos de Joseph Domingo Díaz editor de la Gaceta de Caracas órgano fidelista defensor de los derechos del Rey de España.

  9. Helicobacter pylori VacA enhances prostaglandin E2 production through induction of cyclooxygenase 2 expression via a p38 mitogen-activated protein kinase/activating transcription factor 2 cascade in AZ-521 cells

    DEFF Research Database (Denmark)

    Hisatsune, Junzo; Yamasaki, Eiki; Nakayama, Masaaki

    2007-01-01

    Treatment of AZ-521 cells with Helicobacter pylori VacA increased cyclooxygenase 2 (COX-2) mRNA in a time- and dose-dependent manner. A p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, blocked elevation of COX-2 mRNA levels, whereas PD98059, which blocks the Erk1/2 cascade......A-induced COX-2 expression. In parallel with COX-2 expression, VacA increased prostaglandin E(2) (PGE(2)) production, which was inhibited by SB203580 and NS-398, a COX-2 inhibitor. VacA-induced PGE(2) production was markedly attenuated in AZ-521 cells stably expressing DN-p38. VacA increased transcription...... promoter activation. The reduction of ATF-2 expression in AZ-521 cells transformed with ATF-2-small interfering RNA duplexes resulted in suppression of COX-2 expression. Thus, VacA enhances PGE(2) production by AZ-521 cells through induction of COX-2 expression via the p38 MAPK/ATF-2 cascade, leading...

  10. Efecto de la composición de una mezcla de hidrocarburos en la respuesta fenotípica y la acumulación de azúcares por Bouteloua curtipendula Michx. Torr. en cultivos in vitro

    Directory of Open Access Journals (Sweden)

    Marianela Orozco-Soto

    2015-07-01

    Full Text Available Bouteloua curtipendulaMichx Torr. es un pasto originario de México con gran capacidad de adaptación a condiciones climáticas adversas, ha sido reportado con potencial para fitorremediar suelos contaminados con hidrocarburos (HC. En el presente estudio, se hicieron cultivos in vitro de B. curtipendula con una concentración de 1 500 mg HC·L-1 de medio de cultivo, y distintas mezclas de fenantreno (PHE, pireno (PYR y hexadecano (HXD. En todos los casos, tanto la longitud de brotes y raíces, así como la producción de biomasa disminuyeron signifi cativamente con respecto al control. El 100% de las semillas germinaron en el medio sin HC, mientras que en las mezclas con mayor proporción de HDX (1 100 mg HC·L-1 germinó alrededor del 75% de las semillas. La mayor acumulación de azúcares totales en el medio de cultivo, después de 35 días (40 mg de azúcares totales acumulados en el medio·mg-1 de raíz seca, equivalentes a 200 mg de azúcares totales·tubo se registró en la mezcla con menor concentración de HXD; por otro lado, en los cultivos donde no se adicionó HC se observó un consumo en los azúcares totales (225.7 ± 3 mg azúcares totales·tubo. Los resultados obtenidos sugieren que una mayor proporción de HXD en las mezclas incrementa el efecto tóxico a las plantas. Aunque hay estudios en donde se han cuantificado los azúcares exudados por las raíces, en nuestro conocimiento éste es el primer reporte de cultivos in vitro en donde se observa la producción de azúcares como respuesta de un pasto al estrés por HC.

  11. Microstructure, Residual Stress, Corrosion and Wear Resistance of Vacuum Annealed TiCN/TiN/Ti Films Deposited on AZ31

    Directory of Open Access Journals (Sweden)

    Haitao Li

    2016-12-01

    Full Text Available Composite titanium carbonitride (TiCN thin films deposited on AZ31 by DC/RF magnetron sputtering were vacuum annealed at different temperatures. Vacuum annealing yields the following on the structure and properties of the films: the grain grows and the roughness increases with an increase of annealing temperature, the structure changes from polycrystalline to single crystal, and the distribution of each element becomes more uniform. The residual stress effectively decreases compared to the as-deposited film, and their corrosion resistance is much improved owing to the change of structure and fusion of surface defects, whereas the wear-resistance is degraded due to the grain growth and the increase of surface roughness under a certain temperature.

  12. Cuatro figuras de la música colombiana: Jairo Varela, Diomedes Díaz, Joe Arroyo y Carlos Vives, sus opciones musicales y los debates que sugieren

    Directory of Open Access Journals (Sweden)

    Petrit Baquero

    2015-09-01

     En  ese sentido,  la música  popular puede  constituir la mejor  forma  de  expresar las realidades, vivencias,  los sueños,  las esperanzas y alternativas de vida, con lo cual, los criterios  que impone  la industria cultural  pueden también ser permeados desde abajo por esos localismos que irrumpen de manera permanente. Jairo Varela, Diomedes Díaz, Joe Arroyo y Carlos Vives representan a grandes artistas que, a su manera, transformaron la música colombiana al impulsar  distintos procesos  cuyos efectos se siguen viendo día a día.

  13. Effect of asymmetric rolling process on the microstructure, mechanical properties and texture of AZ31 magnesium alloys sheets produced by twin roll casting technique

    Directory of Open Access Journals (Sweden)

    Selda Ucuncuoglu

    2014-03-01

    Full Text Available Symmetric rolling (SR and asymmetric rolling (ASR processes were carried out on 6 mm thick AZ31 magnesium alloy sheets that were produced by twin roll casting (TRC technique. Before rolling processes, sheets were heat treated in order to obtain a homogenized microstructure. In this study, for the ASR process the rolling speed ratio between upper roller and lower was selected as 1.25. Both SR and ASR processes were utilized with 40% reduction per passes using 2 pass schedule for a total reduction ratio of 0.67. Symmetric and asymmetric rolled sheets were characterized using optical microscopy (OM, scanning electron microscopy (SEM and transmission electron microscopy (TEM techniques. Texture measurements were performed by using X-ray diffraction (XRD technique and mechanical properties were investigated by tensile tests and also hardness measurements.

  14. Factores de riesgo asociados a defectos congénitos: junio 2007- diciembre 2008 en el área de salud "Manuel Díaz Legrá"

    OpenAIRE

    Olga Antonia Álvarez Estrabao; Amparo Buch Núñez; Isora Ballester Quesada

    2009-01-01

    Se realizó un estudio descriptivo, en el área de salud ¿Manuel Díaz Legrá¿ de la provincia Holguín, que incluyó las gestantes y sus recién nacidos atendidos en el periodo de junio 2007 a diciembre 2008, con el objetivo de describir el comportamiento de los factores de riesgo asociados a defectos congénitos. Los factores de riesgo predominantes fueron: la exposición a teratógenos, la edad materna corta y la edad materna avanzada, tanto en la evaluación de las gestantes como en los casos con pe...

  15. IMPACT OF DEPTH OF CUT ON CHIP FORMATION IN AZ91HP MAGNESIUM ALLOY MILLING WITH TOOLS OF VARYING CUTTING EDGE GEOMETRY

    Directory of Open Access Journals (Sweden)

    Olga Gziut

    2015-05-01

    Full Text Available Safety of Mg milling processes can be expressed by means of the form and the number of fractions of chips formed during milling. This paper presents the state of the art of magnesium alloys milling technology in the aspect of chip fragmentation. Furthermore, the impact of the depth of cut ap and the rake angle γ on the number of chip fractions was analysed in the study. These were conducted on AZ91HP magnesium cast alloy and milling was performed with carbide tools of varying rake angle values (γ = 5º and γ = 30º. It was observed that less intense chip fragmentation occurs with decreasing depth of cut ap. The number of chip fractions was lower at the tool rake angle of γ = 30º. The test results were formulated as technological recommendations according to the number of generated chip fractions.

  16. La eliminación de las mujeres trabajadoras rurales del empleo en los campos de caña de azúcar: causas y consecuencias

    Directory of Open Access Journals (Sweden)

    Juliana Biondi Guanais

    2014-01-01

    Full Text Available Este artículo analiza las razones por las cuales las trabajadoras rurales han sido excluidas gradualmente de la tarea del corte de caña en la agroindustria cañera brasileña. Aunque históricamente las mujeres han sido cortadoras de caña de azúcar en Brasil, a partir del año 2000, debido al proceso de reestructuración productiva de la agroindustria, parte impor - tante de la fuerza de trabajo femenina perdió su lugar en el sector. Las pocas mujeres que lograron asegurar su empleo en las fábricas fueron trasladadas a otros puestos de trabajo, realizando funciones secundarias (es decir, menos importantes que el corte de la caña, que son las más devaluadas y precarias, y por lo tanto las peor pagadas.

  17. Azınlığın Zenginliği Hepimizin Çıkarına mıdır?

    OpenAIRE

    Bauman, Zygmunt

    2016-01-01

    25), Daniel Dorning’e atıfla eşitsizliğin, eşitsizlik doktrinine olan inanç sayesinde ayakta kalabildiğinin altını çizmektedir. Yoksa in- sanlar yaşadığımız toplumun ideolojisinde büyük yanlışlıkların ola- bileceğini fark etseler hayretler içerisinde kalacaklardır. Ama eşit- sizlik doktrini üzerinden bu çarpıklıklar gayet güzel bir şekilde gizlenmektedir. Mesela; Dorling eşitsizlik doktrinleri arasında şun- ları saymaktadır: 1) Elitizm faydalıdır. Çünkü tanım gereği sadece nispeten az sayı...

  18. Corrosion resistance and adhesion strength of a spin-assisted layer-by-layer assembled coating on AZ31 magnesium alloy

    Science.gov (United States)

    Zhao, Yan-Bin; Liu, Han-Peng; Li, Chang-Yang; Chen, Yong; Li, Shuo-Qi; Zeng, Rong-Chang; Wang, Zhen-Lin

    2018-03-01

    A polyvinylpyrrolidone (PVP)/polyacrylic acid (PAA) layer-by-layer (LbL) assembled composite coating with a multilayer structure for the corrosion protection of AZ31 magnesium alloy was prepared by a novel spin-casting method. The microstructure and composition of this coating were investigated by means of SEM, XRD and FT-IR measurements. Moreover, electrochemical, immersion and scratch tests in vitro were performed to measure the corrosion performance and the adhesion strength. These results indicated that the (PVP/PAA)10 composite coating with defect-free, dense and uniform morphologies could be successfully deposited on the surface of magnesium alloy. The coating had excellent corrosion resistance and adhesion strength.

  19. Natural and anthropogenic factors affecting the structure of the benthic macroinvertebrate community in an effluent-dominated reach of the Santa Cruz River, AZ

    Science.gov (United States)

    Boyle, T.P.; Fraleigh, H.D.

    2003-01-01

    This study provides an assessment of the ecological conditions of a 46-km effluent-dominated stream section of the Santa Cruz River in the vicinity of the International Waste Water Treatment Plant, Nogales, AZ. We associated changes in the structure of the macroinvertebrate community to natural and anthropogenic chemical and physical variables using multivariate analysis. The analysis shows that biological criteria for effluent-dominated streams can be established using macroinvertebrate community attributes only with an understanding of the contribution of three classes of variables on the community structure: (1) low flow hydrological discharge as affected by groundwater withdrawals, treatment plant discharge, and subsurface geomorphology; (2) chemical composition of the treatment plant discharge and natural dilution; and (3) naturally produced floods resulting from seasonality of precipitation. ?? 2003 Elsevier Science Ltd. All rights reserved.

  20. Las panaderías en la cuidad de México de Porfirio Díaz: los empresarios vasco- navarrosy l a movilización obrrera.

    Directory of Open Access Journals (Sweden)

    Robert Weis.

    2008-04-01

    Full Text Available This article examines the insertion of Basque immigrants from the Baztan Valley, in the province of Navarre, into the wheatflourbread complex of latenineteenth century Mexico City. Additionally, it describes labor conditions in the bakeries they owned and analyzes the place of workers in the Mexico of Porfirio Díaz. In contrast to the historiographical tendency to present immigrant entrepreneurs, and the Porfirian state, as forces of capitalist modernization, the article shows that, with important exceptions, bakeries remained archaic and precapitalist in order to permit the integration of the constant stream of nephews that linked Mexico City and the Baztán Valley. It also argues that the bakery workers, who suffered terrible conditions in the bakery workshops, pushed for a labor regime more in line with capitalism, which, according to popular notions of liberalism, would acknowledge their basic rights as citizens.

  1. Efecto de tipos de labranza sobre la población de malezas en caña de azúcar (Saccharum officinarum L.).

    OpenAIRE

    León, Ramón; Agüero, Renán

    2006-01-01

    En dos lotes de caña de azúcar, uno con baja presión de malezas (lote 1) y otro con alta (lote 2), se evaluaron cuatro tratamientos: cosecha en verde con rastrojo (VCR), cosecha en verde sin rastrojo (VSR), cosecha con quema sin labranza (QSL) y cosecha con quema con labranza (QCL). Se evaluó las especies de malezas así como su población y cobertura del suelo hasta los 75 días después de cosecha, tanto en el surco como en el entre-surco. Además, se evaluó la altura y el número de tallos del c...

  2. Study on interfacial heat transfer coefficient at metal/die interface during high pressure die casting process of AZ91D alloy

    Directory of Open Access Journals (Sweden)

    GUO Zhi-peng

    2007-02-01

    Full Text Available The high pressure die casting (HPDC process is one of the fastest growing and most efficient methods for the production of complex shape castings of magnesium and aluminum alloys in today’s manufacturing industry.In this study, a high pressure die casting experiment using AZ91D magnesium alloy was conducted, and the temperature profiles inside the die were Measured. By using a computer program based on solving the inverse heat problem, the metal/die interfacial heat transfer coefficient (IHTC was calculated and studied. The results show that the IHTC between the metal and die increases right after the liquid metal is brought into the cavity by the plunger,and decreases as the solidification process of the liquid metal proceeds until the liquid metal is completely solidified,when the IHTC tends to be stable. The interfacial heat transfer coefficient shows different characteristics under different casting wall thicknesses and varies with the change of solidification behavior.

  3. Capitales en el azúcar. Los hacendados cubanos ante la rentabilidad económica y la oportunidad de inversión (1878-1895

    Directory of Open Access Journals (Sweden)

    Piqueras Arenas, José A.

    1998-04-01

    Full Text Available This article studies the great hacienda-owners and, in particular, the strategies they applied in order to diversify their income through investment in sugar and other alternative activities, both in and outside Cuba. Investments on these alternative sectors stemmed form return estimations rather than from lack of financial resources.

    Estudio de los grandes hacendados y en particular de las estrategias de diversificación que utilizaron a la hora de invertir en el azúcar y en otras actividades alternativas en Cuba y en el exterior. Las inversiones en cada uno de estos sectores y actividades guardó más relación con un cálculo de rendimientos que con la falta de recursos financieros.

  4. El sueño de Venecia o el guiño de los clásicos en la narrativa de Paloma Díaz-Mas

    Directory of Open Access Journals (Sweden)

    Neus Samblancat

    2010-06-01

    Full Text Available Su artículo propone que la concepción de la obra de Paloma Díaz-Mas, El sueño de Venecia, como palimpsesto literario nos conduce a un análisis intertextual donde cada capítulo de la novela nos remite a un género y a unas voces de época. Los clásicos, como el resto de la producción narrativa de la autora, guiñan el ojo a lo largo de una obra que plantea una reflexión sobre la fragilidad de la razón y de la humana Memoria a la hora de conocer la Historia y de explicar una historia.

  5. Índice normalizado de vegetación en caña de azúcar en la Huasteca Potosina

    OpenAIRE

    N. Aguilar; Galindo, G; J. Fortanelli; Contreras, C.

    2010-01-01

    La aplicación de los Sistemas deInformación Geográfica (SIG) y las técnicas de Percepción Remota (PR) han sido ampliamente investigadas como método para identificar y evaluar el cultivo de caña de azúcar. El objetivo del presente estudio fue estimar y mapear el área bajo el cultivo de caña y evaluar su estado de salud mediante el algoritmo NDVI (Índice Normalizado de Vegetación), derivado del procesamiento e interpretación de imágenes Landsat-7/ETM+. Los resultados mostraron un NDVI en el ran...

  6. Enhanced mechanical properties of tungsten inert gas welded AZ31 magnesium alloy joint using two-pass friction stir processing with rapid cooling

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Nan, E-mail: xunan@hhu.edu.cn; Bao, Yefeng

    2016-02-08

    In this study, tungsten inert gas (TIG) welded AZ31 magnesium alloy joint was subjected to two-pass rapid cooling friction stir processing (RC-FSP). The main results show that, two-pass RC-FSP causes the significant dissolution of the coarse eutectic β-Mg{sub 17}Al{sub 12} phase into the magnesium matrix and the remarkable grain refinement in the stir zone. The low-hardness region which frequently located at heat-affected zone was eliminated. The stir zone showed ultrafine grains of 3.1 μm, and exhibited a good combination of ultrahigh tensile strength of 284 MPa and large elongation of 7.1%. This work provides an effective strategy to enhance the strength of TIG welded magnesium alloy joint without ductility loss.

  7. Entre mythe et histoire : Le roman de Brutus et Dorothée dans le Victorial de Gutierre Díaz de Games (1436

    Directory of Open Access Journals (Sweden)

    Ghislaine Fournès

    2013-06-01

    Full Text Available Cet article a pour but d’étudier à partir d’une double perspective « Le roman de Brutus et Dorothée » inséré dans le Victorial de Gutierre Díaz de Games. Il s’agit, dans un premier temps, de retracer la circulation et la réception du mythe troyen dans la péninsule Ibérique, ceci afin de déterminer la part de création et d’originalité de ces pages, puis, dans un second temps, de mener à bien une analyse des motifs qui constituent ce mythe. Cette réécriture castillane de l’histoire de Brutus témoigne de la validité du mythe troyen au XVe siècle ainsi que de sa portée idéologique.Este artículo tiene como meta estudiar, según una doble perspectiva, “Le roman de Brutus et Dorothée” intercalado en El Victorial de Gutierre Díaz de Games. Se trata, en un primer tiempo, de referir la circulación y la recepción del mito troyano en la península ibérica, para luego determinar el grado de creación y de originalidad de estas páginas, y, en un segundo tiempo, de analizar los motivos que constituyen aquel mito. Esta re-escritura en castellano de la historia de Bruto atestigua la validez del mito troyano durante el siglo XV así como su alcance ideológico.

  8. AZÚCARES EN AGAVES (Agave tequilana Weber CULTIVADOS EN EL ESTADO DE GUANAJUATO Azúcares en agaves (Agave tequilana Weber cultivados en el Estado de Guanajuato

    Directory of Open Access Journals (Sweden)

    L. A. Parra-Negrete

    2012-02-01

    Full Text Available The objetive of this work was to determine if the quality of Guanajuato agaves is equal to the agaves cultivated in Jalisco. A comparative study was made of the sugar content of the agave (A. tequilana Weber cultivated in both states. Used were data of total reducing sugars (%TRS and Brix degrees (ºBx of raw juice samples provided by a tequilera of the region between August and December, 1998 and January and May, 2000. The data were statistically processed, applying an ANOVA analysis and a Tukey test to compare the media and the correlation between °Bx and %TRS was made. In the first period, the media %TRS from the supplier of Manuel Doblado, Gto. was 24.43 ±2.29 and did not show a significant statistical difference (p El objetivo de este trabajo fue determinar si la calidad de los agaves guanajuatenses es igual a la de los cultivados en Jalisco. Se realizó un estudio comparativo del contenido de azúcares de los agaves (A. tequilana Weber cultivados en ambos estados. Se emplearon datos de azúcares reductores totales (%ART agrupados en dos períodos y grados Brix (°Bx de muestras de jugo crudo, proporcionados por una tequilera de la región: agosto a diciembre de 1998 y de enero a mayo del 2000. Los datos se procesaron estadísticamente aplicando un análisis de varianza y prueba de Tukey para comparación de medias. Se determinó la correlación entre los °Bx y el %ART. En el primer período, la media del %ART para el proveedor de Manuel Doblado, Gto. fue de 24.43 ±2.29 y no presentó diferencia estadística significativa (p

  9. Cloning, Expression, Isotope Labeling, and Purification of Transmembrane Protein MerF from Mercury Resistant Enterobacter sp. AZ-15 for NMR Studies

    Directory of Open Access Journals (Sweden)

    Aatif Amin

    2017-07-01

    Full Text Available Mercury resistant (HgR Enterobacter sp. AZ-15 was isolated from heavy metal polluted industrial wastewater samples near to districts Kasur and Sheikhupura, Pakistan. 16S rDNA ribotyping and phylogentic analysis showed 98% homology with already reported Enterobacter species. The merF gene encoding transmembrane protein-MerF was amplified from genomic DNA and ligated into pET31b+ vector using restriction endonucleases, SphI and XhoI. The genetic codons of merF gene encoding cysteine residues were mutated into codons, translating into serine residues by site-directed mutagenesis. Ketosteroid isomerase (KSI, a fusion tag which is present in pET31b+ vector, was used in the expression of merFm gene. KSI was used to drive the target peptide (MerFm into inclusion bodies so that the peptide yield and purity were increased. The stable plasmid pET31b+:merFm was transformed into C43(DE3 E.coli cells. The high expression of uniformly 15N isotopically labeled-MerFm protein was induced with 1 mM IPTG. The purification of 15N-MerFm recombinant protein by Ni-NTA and size exclusion chromatography involved an unfolding/refolding procedure. The two-dimensional HSQC NMR spectra of MerFm protein showed the purity and correct number of resonances for each amide. 1H–15N HSQC NMR experiment also confirmed that no modification of the tryptophan residue occurred during cyanogen bromide cleavage. A small scale reservoir of Luria Bertani (LB medium supplemented with 20 μg/ml of HgCl2 showed 90% detoxification of Hg by Enterobacter sp. AZ-15. The accumulation of Hg on the cell surface of this strain was visualized by scanning electron microscopy (SEM which confirmed its potential use in Hg-bioremediation.

  10. Effect of biologically relevant ions on the corrosion products formed on alloy AZ31B: an improved understanding of magnesium corrosion.

    Science.gov (United States)

    Jang, Yongseok; Collins, Boyce; Sankar, Jagannathan; Yun, Yeoheung

    2013-11-01

    Simulated physiological solutions mimicking human plasma have been utilized to study the in vitro corrosion of biodegradable metals. However, corrosion and corrosion product formation are different for different solutions with varied responses and, hence, the prediction of in vivo degradation behavior is not feasible based on these studies alone. This paper reports the role of physiologically relevant salts and their concentrations on the corrosion behavior of a magnesium alloy (AZ31B) and subsequent corrosion production formation. Immersion tests were performed for three different concentrations of Ca(2+), HPO4(2-), HCO3(-) to identify the effect of each ion on the corrosion of AZ31B assessed at 1, 3 and 10 days. Time-lapse morphological characterization of the samples was performed using X-ray computed tomography and scanning electron microscopy. The chemical composition of the surface corrosion products was determined by electron dispersive X-ray spectroscopy and X-ray diffraction. The results show that: (1) calcium is not present in the corrosion product layer when only Cl(-) and OH(-) anions are available; (2) the presence of phosphate induces formation of a densely packed amorphous magnesium phosphate corrosion product layer when HPO4(2-) and Cl(-) are present in solution; (3) octacalcium phosphate and hydroxyapatite (HAp) are deposited on the surface of the magnesium alloy when HPO4(2-) and Ca(2+) are present together in NaCl solution (this coating limits localized corrosion and increases general corrosion resistance); (4) addition of HCO3(-) accelerates the overall corrosion rate, which increases with increasing bicarbonate concentration; (5) the corrosion rate decreases due to the formation of insoluble HAp on the surface when HCO3(-), Ca(2+), and HPO4(2-) are present together. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  11. Comportamiento superplástico de una aleación AZ61 procesada por extrusión en canal angular

    Directory of Open Access Journals (Sweden)

    Eddahbi, M.

    2006-04-01

    Full Text Available This study is concerned with microstructural and mechanical characterization of the superplastic behaviour of a magnesium base AZ61 alloy processed by equal channel angular extrusion (ECA. Microscopic examinations showed that the microstructure after ECA was homogeneous and the grain size was about 5 mm. The extruded material showed better mechanical properties than the rolled material. The strain rate sensitivity exponent, at 250 ºC, was 0.5 at strain rates ranging from 10-4 to 5 . 10-4 s-1. Under these conditions, the maximum elongation obtained was 250 % and the microstructure remained homogeneous and stable. Furthermore, the stress strain curves showed strong strain hardening which was not attributed exclusively to dynamic grain growth.

    En este trabajo se estudia el comportamiento superplástico, tanto mecánico como microestructural, de una aleación de base magnesio AZ61 procesada por extrusión en canal angular (ECA. Las observaciones microscópicas revelaron que la microestructura después de ECA es muy homogénea y el tamaño de grano es de aproximadamente 5 mm. El material extruido, comparado con el material laminado, muestra buenas propiedades mecánicas. El exponente de la sensibilidad a la velocidad de deformación, a 250 ºC, es próximo a 0,5 en el intervalo de velocidades entre 10-4 y 5 . 10-4 s-1 y el máximo alargamiento obtenido es de 250 %. La microestructura permanece muy homogénea y estable durante la deformación superplástica. Además, las curvas de tensión deformación muestran un importante endurecimiento que, en este caso, no se puede atribuir únicamente al crecimiento dinámico de grano.

  12. Pretratamiento de residuos de plátano (Musa paradisiaca (L. AAB y arracacha (Arracacia xanthorrhiza Bancroft para la obtención de azúcares fermentables

    Directory of Open Access Journals (Sweden)

    Darwin Carranza Saavedra

    2015-09-01

    Full Text Available El raquis de plátano Musa paradisiaca L. (AAB y el tallo cilíndrico corto (cepa que posee la arracacha (Arracacia xanthorrhiza Bancroft son los principales residuos generados durante el manejo poscosecha en la región del Tolima (Colombia. Muestras secas fueron sometidas a hidrólisis térmica a presiones de 0,1034 MPa (100,55 ºC; 0,2068 MPa (121,28 ºC y 0,4137 MPa (144,83 ºC de vapor saturado; a hidrólisis con ácido sulfúrico en concentraciones de 0,25; 0,50 y 1,00 M con calentamiento durante 1 y 2 horas; y por último se sacarificó con empleo de enzimas celulasas (Celluclast® 1.5 L a concentraciones de 7,5; 15,0 y 30,0 FPU/g. Los mejores rendimientos de carbohidratos reductores se obtuvieron al tratar el raquis y la cepa con ácido sulfúrico a concentración de 1,00 M por 1 hora de tiempo residencia. La torta resultante del proceso de filtración se hidrolizó enzimáticamente arrojando altas cantidades de obtención de azúcares fermentables en todo el proceso de 0,7734 g/g a partir del raquis (30 FPU/g y 0,7679 g/g a partir de la cepa (15 FPU/g. Los residuos agrícolas de plátano y arracacha pueden ser utilizados en la generación de azúcares fermentables.

  13. Efecto de tipos de labranza sobre la población de malezas en caña de azúcar

    Directory of Open Access Journals (Sweden)

    Ram\\u00F3n Le\\u00F3n

    2001-01-01

    Full Text Available En dos lotes de caña de azúcar, uno con baja presión de malezas (lote 1 y otro con alta (lote 2, se evaluaron cuatro tratamientos: cosecha en verde con rastrojo (VCR, cosecha en verde sin rastrojo (VSR, cosecha con quema sin labranza (QSL y cosecha con quema con labranza (QCL. Se evaluó las especies de malezas así como su población y cobertura del suelo hasta los 75 días después de cosecha, tanto en el surco como en el entre-surco. Además, se evaluó la altura y el número de tallos del cultivo por metro lineal. No se observaron diferencias entre las poblaciones de malezas en el lote 1. En el lote 2 las malezas se vieron beneficiadas por la labranza y por la quema; así los tratamientos QSL y QCL mostraron las mayores coberturas, siendo este último el que presentó las poblaciones más altas y en el que se dió una disminución en el número y altura de tallos de la caña de azúcar. Cyperus rotundus L. y Rottboellia cochinchinensis (Lour Clayton presentaron las mayores coberturas, especialmente en QCL. En el surco se dio un desarrollo superior de las poblaciones de malezas, al observado en el entre-surco, ya que presentó mejores condiciones de germinación y disponibilidad de nutrimentos

  14. Az arcvédő hazugság. A szívességkérés elutasításában megjelenő hazugság vizsgálata

    Directory of Open Access Journals (Sweden)

    Falyuna, Nóra

    2016-03-01

    Full Text Available The face saving lie. Using lie as a strategy in the speech act of refusal of request *** The topic of the research was the role of the lie in the speech act of refusal. The theoretical background has been composed of three tenets: 1 review of the literature on lie and the formulation of a work definition; 2 the pragmatics of the speech act of refusal and 3 the face-threatening and the face-saving and the theory of the cognitive dissonance. There were three research questions: 1 is lie a preferred strategy used in refusals in Hungarian, and if yes what is its function; 2 how is this strategy evaluated by the communicators after having carried out the act; 3 what are the reason for choosing and accepting lie as a strategy in Hungarian refusals? The main instruments of the data collection were two questionnaire: the first was a discourse completion test, the second was a retrospective questionnaire. Based on the data collected lie was proven to be a common and accepted linguistic strategy in refusals. This strategy use is conscious, contains the intention of deceiving, it represents untrue content and its aim is to save the faces of the participants of the interaction. *** A kutatás a szívességkérés elutasításában megjelenő hazugság szerepét vizsgálta. A kutatás elméleti kerete három részből állt: 1 a hazugságra vonatkozó szakirodalom tanulmányozása alapján megfogalmazott munkadefiníció; 2 az elutasítás, valamint 3 az arcvédés és az arcfenyegetés pragmatikai megközelítése, illetve a kutatás során ezzel összefüggésbe hozott kognitív disszonanciaelmélet. Az empirikus kutatás egy pilot kutatás volt, amely három kutatási kérdés köré szerveződött: 1 megjelenik-e, és ha igen, hogyan jelenik meg a hazugság a szívességkérés elutasításában; 2 a választott elutasító stratégia utólag milyen megítélés alá esik az elutasító fél oldaláról; 3 mi indokolja az adott stratégia v

  15. Derecho, Filosofía y Política: La lección de Elías Díaz

    Directory of Open Access Journals (Sweden)

    Vargas-Machuca Ortega, Ramón

    2008-12-01

    Full Text Available Elías Díaz is one of the most relevant Spanish intellectuals of the last 50 years and has opened up new paths in the fields of his plural research. Firstly, in its recuperation of Spain’s recent intellectual past, his work is pioneering and distinctive. It underlines the link between liberalism and democracy, secularization and reformism, and traces certain lines of continuity in our fragmented history. Secondly, as the central thesis of his contribution to the Theory of Law, he defends the fact that the internal relationship between Law and the Theory of Justice is based on the principles that inspire Constitutional Democracy. Lastly, in his Political Philosophy he aims to overcome the lack of connection between Public Ethics and Law and to facilitate the move in Politics from theory to practice in order to achieve an «integrated life». In their reconsideration of his work on the occasion of his retirement, Elías Díaz’s disciples and colleagues have not only paid an original tribute to their «Master» but have also set a great example and taught an excellent lesson to all lovers of Law, Philosophy and Politics.

    Elías Díaz es uno de los más relevantes intelectuales españoles de los últimos cincuenta años que ha abierto nuevas sendas en los campos de su plural investigación. Primeramente, en la recuperación del reciente pasado intelectual de España su obra es pionera y distintiva: subraya el vínculo entre liberalismo y democracia, secularización y reformismo al tiempo que rastrea ciertas líneas de continuidad en una historia fragmentada. En segundo lugar, como tesis central de su aportación a la Teoría del Derecho defiende que la relación interna entre Derecho y Teoría de la Justicia se funda en los principios que inspiran la democracia constitucional. Finalmente, en su Filosofía Política trata de superar la desconexión entre Ética Pública y Derecho así como facilitar en el campo de la política el tr

  16. Solidification of AM and AZ magnesium alloys characterized by heat-transfer modeled thermal and calorimetric analysis and microsegregation study of directionally solidified microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Mirkovic, Djordje

    2008-05-09

    The micro-scale solidification of commercial Mg alloys of the AZ and AM series is in the focus of the present thesis. Two approaches of investigating solidification are implemented, complementary regarding temperature gradient and solidification rate, and also with respect to the generated microstructure. The first approach considers solidification under a negligible spatial temperature gradient. Here the solidification curves, i.e. fraction solid versus temperature, were determined by developing an improved heat-transfer modeling applicable on both differential thermal analysis (DTA) and differential scanning calorimetry (DSC) signals. The correlation between solidification enthalpy and fraction solid during solidification was tested in detail. A better evaluation of the measured DTA and DSC signals is attained through an independent measurement of the time constant as function of temperature for the applied equipment. A further improvement is achieved through a more impartial interpretation of the measured curves. Both improvements enable a better desmearing of measured signals and reduce the error induced by the operator. The novel tantalum encapsulation enabled appropriate handling of challenging Mg-alloys. The viability and limitations of thermal analysis in general to determine start and end of solidification of AZ magnesium alloys was also studied. The second approach is based on directional solidification in a high temperature gradient and at constant solidification rate, achieved by the Bridgman technique. The resulting dendritic microstructure and inherent microsegregation are studied in this work. The solute profiles, i.e. solute content versus solid phase fraction during solidification, are determined by an advanced treatment of the EPMA data. Problems that are demonstrated in this work are Al-loss and melt pollution due to reaction with typical sample container material made of unprotected steel. The development of an optimized boron nitride (BN

  17. Método para determinar la cantidad de agua de imbibición a utilizar en la industria de azúcar de caña

    Directory of Open Access Journals (Sweden)

    Félix González-Pérez

    2010-01-01

    Full Text Available Se hizo un estudio del uso del agua de imbibición en la industria del azúcar de caña de Cuba y, se revisaron más de 200 fuentes bibliográficas llegándose a conclusiones importantes en cuanto a la cantidad y temperatura del agua de imbibición, así como la revisión del esquema de imbibición más utilizado.A partir de aquí se obtiene un procedimiento para determinar la cantidad óptima de agua de imbibición teniendo en cuenta los precios actualizados del azúcar y el bagazo como combustible y para otros usos, Es utilizado para su validación en dos empresas azucareras de la provincia de Cienfuegos, se obtuvo que en las condiciones económicas actuales, es recomendable utilizar entre 10,4 – 15,4 % caña en dependencia del uso que se le dé al bagazo y no entre 18-22 % caña como se viene haciendo históricamente, lo que permitió lograr un ahorro de agua de 66670,1 t, esto hace que se ahorren 9531.77 kWh de energía eléctrica por bombeo, permitiendo un efecto económico total entre 22939,92 – 218505,47 USD.A study was performed of the use of the water of imbibition in the industry of the sugar cane of Cuba and internationally. More than 200 bibliographical sources were reviewed reaching important conclusions as far as the amount and temperature from the imbibition water, as well as the scheme used of imbibition water most commonly used.A very simple procedure is obtained to determine the optimal amount of imbibition water considering the updated prices of the sugar and the bagasse as fuel and for other uses. It is applied for his validation in two sugar companies of the province of Cienfuegos. In the present economic conditions the results showed that it is advisable to use an amount of imbibition water between 10.4 -15,4 % of the amount of cane processed based on the use of the bagasse and not between 18-22% as it is historically done. It resulted on 66670.1 tons of water and 9531.77 kWh of electrical energy saved. The total

  18. Costos de producción de vaquillas Holstein con ensilado de caña de azúcar o de maíz

    Directory of Open Access Journals (Sweden)

    J. A. Reyes

    2006-01-01

    Full Text Available El objetivo del presente trabajo fue evaluar los costos de producción de vaquillas Holstein mediante la comparación de dos sistemas de alimentación, basados en ensilado de caña de azúcar (ECA vs el sistema tradicional del rancho basado en ensilado de maíz (EM. En ambos casos, con suplementación a los animales. Se utilizaron 28 becerras posterior al destete, con una edad promedio de 80±16 días y un peso inicial de 79.5 ± 12.9 kg. El estadístico fue un análisis de varianza para un diseño en bloques al azar, en donde el peso fue el factor de bloqueo y se dividieron en tres grupos dentro de cada tratamiento. Cada 30 días se midió la ganancia diaria de peso GDP (kg, la condición corporal CC, la conversión alimenticia CA (kg, el consumo de forraje CF (kg, de suplemento CS (kg, costo de alimentación/ día y la determinación del costo de producción de los reemplazos ($. Las vaquillas tuvieron una GDP 0.666 y 0.743 kg/día, CC 3.1b y 3.7a, CA 7.4a y 9.8b, CF 3.2 y 5.3, CS 1.8 y 1.5, costo de alimentación/día 9.4a y 11.4b y costo de la vaquilla $6,986.82 y $8,034.39, para ECA y EM, respectivamente. La alimentación fue el rubro que mayor impacto tuvo en la obtención de vaquillas de reemplazo, con 67 a 71% de los costos totales y la etapa de mayor inversión en la producción de vaquillas correspondió a la fase del nacimiento al destete. La alimentación basada en ensilaje de caña de azúcar permitió un mejor comportamiento económico para la producción de vaquillas de reemplazo, comparado con el sistema tradicional con ensilado de maíz.

  19. The effect of charged axial ligands on the EPR parameters in oxovanadium(IV) compounds: an unusual reduction of the Az (51V) values.

    Science.gov (United States)

    Tolis, E J; Teberekidis, V I; Raptopoulou, C P; Terzis, A; Sigalas, M P; Deligiannakis, Y; Kabanos, T A

    2001-06-18

    Two series of octahedral oxovanadium(IV) compounds, containing charged or neutral axial ligands, with the tetradentate amidate molecules Hcapca and H2capcah of the general formulae trans-[V(IV)OX(capca)]0/+ (where X = Cl- (1.CH2Cl2), SCN- (2), N3 (3), CH3COO- (4), PhCOO- (5), imidazole (6. CH3NO2), and eta-nBuNH2 (7)) and cis-[V(VI)OX(Hcapcah)]0/+ (where X = Cl- (8.0.5CH2Cl2), SCN (9), N3 (10.2CH3OH), and imidazole (11)), were synthesized and characterized by X-ray crystallography (1.CH3OH,8.CHCl3, 9.2CH3CN, 10.CH3CN and cis-[VO(imidazole)(Hcapcah)+) and continuous-wave electron paramagnetic resonance (cw EPR) spectroscopy. In addition to the synthesis, crystallographic and EPR studies, the optical, infrared and magnetic properties (room temperature) of these compounds are reported. Ab initio calculations were also carried out on compound 8 CHCl3 and revealed that this isomer is more stable than the trans isomer, in good agreement with the experimental data. The cw EPR studies of compounds 1-5, that is, the V(IV)O2+ species containing monoanionic axial ligands, revealed a novel phenomenon of the reduction of their A, components by about 10% relative to the N4 reference compounds ([V(IV)O-(imidazole)4]2+ and [V(IV)O(2,2-bipyridine)2]2+). In marked contrast, such a reduction is not observed in compounds 6. CH3NO2-11, which contain neutral axial ligands. Based on the spin-Hamiltonian formalism a theoretical explanation is put forward according to which the observed reduction of Az is due to a reduction of the electron - nuclear dipolar coupling (P). The present findings bear strong relevance to cw EPR studies of oxovanadium(IV) in vanadoproteins, V(IV)O2+-substituted proteins, and in V(IV)O2+ model compounds, since the hyperfine coupling constant, Az, has been extensively used as a benchmark for identification of equatorial-donor-atom sets in oxovanadium(IV) complexes.

  20. Comportamiento del área foliar específica en tres cultivares comerciales de caña de azúcar

    Directory of Open Access Journals (Sweden)

    Isabel Torres Varela

    2015-05-01

    Full Text Available RESUMEN Tomando como base experimental dos ensayos de campo ubicados en la Estación Territorial de Investigaciones de la Caña de Azúcar de Camagüey, se realizaron a través de muestreos periódicos las determinaciones del área foliar específica en las variedades de caña de azúcar: C1051-73, My5514 y C86-12, en edades que oscilaron según la fecha de plantación entre los 279 y los 480 días. El cultivar C1051-73 presentó los más bajos niveles del área foliar específica, lo que se corresponde con hojas de mayor espesor relativo o densidad. Los niveles del área foliar específica en cada cultivar no difiere en cada ciclo de plantación. En primavera se observan diferencias estadísticas entre una edad y la siguiente en el período que va desde 300 y hasta 421 días. En frío las cifras resultan más homogéneas, con diferencias medibles entre edades de 279 a 300 días y entre 367 y 394 días. El contrate simultáneo entre cultivares y edades muestra de modo regular pocas diferencias biométricas. Specific leaf area in three comercial sugarcane varieties. ABSTRACT Taking as experimental base two trials of field located in the Experiment Station of Sugarcane Research of Camagüey (INICA–AZCUBA, carried out with periodic sampling the growth analysis in three commercial sugarcane varieties: C1051-73, My5514 and C86-12, for it calculate a development index, specific leaf area, in ages that oscillated according to the plantation date between the 279 and the 480 days. C1051-73 presented the lowest levels in the specific leaf area, it’s belongs with leaves of more relative thickness or density. The levels of specific leaf area in each cultivar it doesn't differ in each plantation cycle. In spring statistical differences are observed between an age and the following one in the period understood from 300 until 421 days. In cold the values are more homogeneous, with appraisable differences among ages of 279 to 300 days and between 367 and