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Sample records for ba estefade az

  1. Gömülü süt ikinci azı dişine bağlı olarak meydana gelen perikoronitis vakası

    Directory of Open Access Journals (Sweden)

    Fatih Sari

    2011-10-01

    Full Text Available

    Primary tooth impaction has been reported to be very rare and studies report prevalence rates of impaction to be form 1:10.000. Primary tooth impactions can occur because of various reasons, including ankylosis, congenitally missing permanent teeth, defects in periodontal membrane, trauma, injury of the periodontal ligament, precocious eruption of the first permanent molar, defective eruptive force, or a combination of these factors. In this article we present a case of impacted mandibular second deciduous molar tooth with pericoronitis and discuss the etiology and its management by surgical intervention in an 8 year old girl.

     

    ÖZET

    Gömülü süt dişlerine ait çok az sayıda rapor vardır ve bu çalışmalarda süt dişlerinin gömülü kalma insidansı 10.000’de 1 olarak belirtilmiştir. Çeşitli nedenler süt dişlerinin gömülü kalmasına neden olabilmektedir. Bunlar; ankiloz, konjenital olarak daimi diş eksikliği, periodontal membranda defekt, travma, periodontal ligamentte yaralanma, erken süren daimi birinci molar, hatalı sürme kuvvetleri ya da bu faktörlerin kombinasyonlarıdır. Bu raporda 8 yaşındaki bir kız çocuğunun gömülü süt alt ikinci azı dişine bağlı olarak gelişen perikoronitis vakası sunulmuş, etyolojik faktörler ve cerrahi tedavi seçeneği tartışılmıştır.

    Anahtar Kelimeler: Gömülü süt dişi, perikoronitis, ankiloz

  2. Hot Cracking in AZ31 and AZ61 Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    C.J. Huang; C.M. Cheng; C.P. Chou; F.H. Chen

    2011-01-01

    This paper examined the impact of the number of thermal cycles and augmented strain on hot cracking in AZ31 and AZ61 magnesium alloy. Statistical analyses were performed. Following observation using a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS) was used for component analysis. Results showed that Al content in magnesium alloy has an effect on hot cracking susceptibility. In addition, the nonequilibrium solidification process produced segregation in Al content, causing higher liquid Mg-alloy rich Al content at grain boundaries, and resulting into liquefied grain boundaries of partially melted zone (PMZ). In summary, under multiple thermal cycles AZ61 produced serious liquation cracking. AZ61 has higher (6 wt%) Al content and produced much liquefied Mg17Al12 at grain boundaries under multiple thermal cycles. The liquefied Mg17Al12 were pulled apart and hot cracks formed at weld metal HAZ due to the augmented strain. Since AZ31 had half the Al content of AZ61, its hot-cracking susceptibility was lower than AZ61. In addition, AZ61 showed longer total crack length (TCL) in one thermal cycle compared to that in three thermal cycles. This phenomenon was possibly due to high-temperature gasification of Al during the welding process, which resulted in lower overall Al content. Consequently, shorter hot cracks exhibited in three thermal cycles. It was found the Al content of AZ31 and AZ61 can be used to assess the hot-cracking susceptibility.

  3. Forging of Mg-alloys AZ31 and AZ80

    Energy Technology Data Exchange (ETDEWEB)

    Viehweger, B.; Karabet, A.; Duering, M. [Brandenburg University of Technology, Interdisciplinary Research Centre for Lightweight Materials ' ' Panta Rhei' ' , Konrad-Wachsmann-Allee 17, 03046 Cottbus (Germany); Schaeffer, L. [Universidade Federal do Rio Grande do Sul, Porto Alegre (Brazil)

    2005-05-01

    Mg-wrought alloys recently became an engineer material of constantly increasing interest. The mechanical properties of extruded Mg-feedstock of the alloys AZ80 and AZ31 indicate their suitability for automotive applications in form of high-quality forgings. Therefore a detailed knowledge about the forming behaviour is of particular importance. In order to compare mechanical properties of available Mg-feedstock qualities compression tests at room temperature have been carried out by applying batches of AZ31- and AZ80-feedstock. Cylindrical specimens were made out of received continuously casted as well as extruded AZ31- and AZ80 - rods. A quantitative analysis of Mg-feedstock's microstructure has been carried out. The characterization of the deformability of applied Mg-feedstock under hot working conditions could be performed by means of uniaxial plain strain upsetting tests at temperatures between 300 and 450 C as well as logarithmic strain rates of 10{sup -1}, 1 and 10s{sup -1}. It is shown that the chosen parameter range ensures an enhanced deformability of continuously as well as extruded Mg-feedstock. The subsequently carried out determination of microstructural evolution could be related to obtained flow stress curves of applied batches of Mg-feedstock. Furthermore, FVM/FEM-systems have been employed in order to design a simplified geometry of heated forging dies suitable for forging tests. The tests have been carried out by means of a hydraulic press. During the tests their punch velocity has been varied between 1 and 40 mm/s. Hence numerically simulated results could be confirmed by practical tests. Exemplary forgings of a simplified shape were made out of all applied batches of Mg-feedstock. No remarkable failures have been detected. (Abstract Copyright [2005], Wiley Periodicals, Inc.) [German] Das Interesse an Mg-Knetlegierungen als Konstruktionswerkstoff fuer automobile Anwendung ist in juengster Zeit stark gewachsen. Daher ist eine detaillierte

  4. 碱土元素对AZ91D镁合金组织和性能的影响%Effects of Mixed Addition of Alkaline Earth Element on Microstructure and Properties of AZ91D Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    徐云龙; 陈刚; 赵玉涛; 万鹏; 姚宏博; 张道理

    2009-01-01

    通过向AZ91D合金中添加Ca、Ba、Sr3种碱土元素,熔炼制备了铸态镁合金,利用OM、SEM、EDS和XRD等手段研究了合金的铸态组织和物相组成,测试了其力学性能.结果表明, Ca、Ba、Sr的综合作用可以显著细化镁合金的铸态组织,并使网络状β-Mg17Al12相以球块状弥散分布,室温抗拉强度从AZ91D合金的156.3 MPa提高到AZ91D-0.5Ca-0.2Ba-0.1Sr合金的187.6 MPa.

  5. EnviroAtlas - Phoenix, AZ - Block Groups

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Phoenix, AZ EnviroAtlas area. The block groups are from the US Census Bureau and are included/excluded based on...

  6. Spectroscopic Classification of ASASSN-16az

    Science.gov (United States)

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

    2016-02-01

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

  7. Barium phosphate conversion coating on die-cast AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Poor corrosion resistance limits the application of magnesium alloys.Conversion coating is widely used to protect magnesium alloys because of easy operation and low cost.A novel conversion coating on die.cast AZ91D magnesium alloy containing barium salts was studied.The optimum concentrations of Ba(NO3)2,Mn(NO3)2 and NH4H2PO4 are 25 g/L,15 mL/L and 20 g/L,respectively,based on orthogonal test resulm.The treating time,solution temperature and PH value are settled to be 5-30 min,50-70℃and 2.35-3.0.respectively.The corrosion resistance of barium conversion coating is better than that of manganese-based phosphate conversion coating by immersion test.The coating is composed of Ba,P, O,Mg,Zn,Mn and Al by EDX analysis.

  8. Comparison of corrosion behaviors of AZ31, AZ91,AM60 and ZK60 magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    CHENG Ying-liang; QIN Ting-wei; WANG Hui-min; ZHANG Zhao

    2009-01-01

    The corrosion behaviours of four kinds of rolled magnesium alloys of AZ31, AZ91, AM60 and ZK60 were studied in 1 mol/L sodium chloride solution. The results of EIS and potentiodynamic polarization show that the corrosion resistance of the four materials is ranked as ZK60>AM60>AZ31>AZ91. The corrosion processes of the four magnesium alloys were also analyzed by SEM and energy dispersive spectroscopy(EDS). The results show that the corrosion patterns of the four alloys are localized corrosion and the galvanic couples formed by the second phase particles and the matrix are the main source of the localized corrosion of magnesium alloys. The corrosion resistance of the different magnesium alloys has direct relationship with the concentration of alloying elements and microstructure of magnesium alloys. The ratio of the β phase in AZ91 is higher than that in AZ31 and the β phase can form micro-galvanic cell with the alloy matrix, as a result, the corrosion resistance of AZ31 will be higher than AZ91. The manganese element in AM60 magnesium alloy can form the second phase particle of AlMnFe, which can reduce the Fe content in magnesium alloy matrix, purifying the microstructure of alloy, as a result, the corrosion resistance of AM60 is improved. However, due to the more noble galvanic couples of AlMnFe and matrix, the microscopic corrosion morphology of AM60 is more localized. The zirconium element in ZK60 magnesium alloy can refine grain, form stable compounds with Fe and Si, and purify the composition of alloy, which results in the good corrosion resistance of ZK60 magnesium alloy.

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

    Science.gov (United States)

    Rostejnska, Milada; Klimova, Helena

    2011-01-01

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

  10. 78 FR 57923 - Arizona Disaster #AZ-00029

    Science.gov (United States)

    2013-09-20

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

  11. 76 FR 42156 - Arizona Disaster #AZ-00016

    Science.gov (United States)

    2011-07-18

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

  12. 76 FR 45644 - Arizona Disaster #AZ-00016

    Science.gov (United States)

    2011-07-29

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

  13. 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.

  14. Tank 241-AZ-102 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-102 (AZ-102) sampling activities. Tank AZ-102 is currently a non-Watch List tank, so the only DQOs applicable to this tank are the safety screening DQO and the compatibility DQO, as described below. The current contents of Tank AZ-102, as of October 31, 1994, consisted of 3,600 kL (950 kgal) of dilute non-complexed waste and aging waste from PUREX (NCAW, neutralized current acid waste). Tank AZ-102 is expected to have two primary layers. The bottom layer is composed of 360 kL of sludge, and the top layer is composed of 3,240 kL of supernatant, with a total tank waste depth of approximately 8.9 meters.

  15. Effect of coolant inhibitors on AZ91D

    Institute of Scientific and Technical Information of China (English)

    I.M. Baghni; WU Yinshun; ZHANG Wei; LI Jiuqing

    2004-01-01

    The inhibition effects of sodium vanadate along with inorganic coolant inhibitors were examined on corrosion of AZ91D in ASTM D1384-80 corrosive water by polarization measurements. The galvanic corrosion of AZ91D coupled to 3003, 6063, and 356 Al alloys were also tested. An effective combination of inhibitors containing (but not limited to) sodium vanadate, silicate, and nitrate was proposed for inhibition of AZ91D and prevention of galvanic corrosion.

  16. 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.

  17. Hot deformation behavior and dynamic recrystallization kinetics of AZ61 and AZ61 + Sr magnesium alloys

    Directory of Open Access Journals (Sweden)

    S. Aliakbari Sani

    2016-06-01

    Full Text Available In this study, the effect of strontium addition on hot deformation of AZ61 alloy was investigated by hot compression tests. A reference alloy (AZ61 and an Sr-containing alloy (AZ61 + Sr was cast while their average initial grain size were supposed to be about 140 and 40 µm, respectively. In AZ61 + Sr alloy, the Sr-containing precipitations were stable at homogenization temperature. Analysing the hot compression curves, it was revealed that dynamic recrystallization phenomenon had occurred and controlled the thermomechanical behaviour of the alloys. The derived constitutive equations showed that the hot deformation parameters (n and Q in AZ61 + Sr alloy is smaller than those of AZ61 alloy; this can be related to the small initial grain size and the lower amounts of solute aluminium atoms. The analysis of DRX kinetics along with the micrographs of the deformed microstructures showed that at the same condition the development of DRXed microstructure in AZ61 + Sr alloy was faster than AZ61 alloy. The increased recrystallized microstructure was interpretated to be attributed to (1 the more grain boundaries present and (2 the existance of the Al-Mg-Sr precipitations assisted the PSN mechanism. Also, the attenuated intensity of the basal texture of AZ61 + Sr was related to the DRX fraction of microstructure.

  18. 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.

  19. Azúcar y diabetes: recomendaciones internacionales

    OpenAIRE

    Álejandro Sanz París; Diana Boj Carceller; Isabel Melchor Lacleta; Ramón Albero Gamboa

    2013-01-01

    La nutrición en el paciente diabético no es sólo un del mero aporte de nutrientes sino que es la base su tratamiento. De hecho, las sociedades científicas internacionales lo han denominado "tratamiento médico nutricional" para darle el énfasis que se merece. Las recomendaciones nutricionales de las sociedades científicas han ido cambiando en los últimos años con la medicina basada en la evidencia. Respecto al consumo de azúcar, la mayoría considera que no afecta el control metabólico si éste ...

  20. 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.

  1. 76 FR 18378 - Amendment of Class E Airspace; Taylor, AZ

    Science.gov (United States)

    2011-04-04

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

  2. Corrosion product layers on magnesium alloys AZ31 and AZ61: Surface chemistry and protective ability

    Energy Technology Data Exchange (ETDEWEB)

    Feliu, S., E-mail: sfeliu@cenim.csic.es; Llorente, I.

    2015-08-30

    Highlights: • Surface chemistry of the corrosion product layers on magnesium alloys. • Influence of the type of alloy on the carbonate surface enrichment. • Relation between surface composition and protection properties. - Abstract: This paper studies the chemical composition of the corrosion product layers formed on magnesium alloys AZ31 and AZ61 following immersion in 0.6 M NaCl, with a view to better understanding their protective action. Relative differences in the chemical nature of the layers were quantified by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDX) and low-angle X-ray diffraction (XRD). Corrosion behavior was investigated by Electrochemical Impedance Spectroscopy (EIS) and hydrogen evolution measurement. An inhibitive effect from the corrosion product layers was observed from EIS, principally in the case of AZ31, as confirmed by hydrogen evolution tests. A link was found between carbonate enrichment observed by XPS in the surface of the corrosion product layer, concomitant with the increase in the protective properties observed by EIS.

  3. Azúcar y diabetes: recomendaciones internacionales

    Directory of Open Access Journals (Sweden)

    Álejandro Sanz París

    2013-07-01

    Full Text Available La nutrición en el paciente diabético no es sólo un del mero aporte de nutrientes sino que es la base su tratamiento. De hecho, las sociedades científicas internacionales lo han denominado "tratamiento médico nutricional" para darle el énfasis que se merece. Las recomendaciones nutricionales de las sociedades científicas han ido cambiando en los últimos años con la medicina basada en la evidencia. Respecto al consumo de azúcar, la mayoría considera que no afecta el control metabólico si éste se sustituye por otros hidratos de carbono, pero no se indica una cantidad concreta.

  4. 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...

  5. Structure evolution of AZ61 magnesium alloy in SIMA process

    Institute of Scientific and Technical Information of China (English)

    YAN Hong; ZHANG Fa-yun; JIE Xiao-ping

    2005-01-01

    The effect of prior compressive deformation, isothermal temperature and holding time on the structure of AZ61 magnesium alloy fabricated by strain-induced melt activation(SIMA) processing was investigated. The specimens were subjected under deformation ratios of 0%, 22% and 40% and various heat treatment time and temperature regions. The results indicate that the ideal technological parameters of semi-solid AZ61 alloy produced with non-dendrites are recommended as 22% (prior compressive deformation), 595 ℃ (heat treatment temperature) and 40 min(time). The as-cast AZ61 magnesium alloy isn't fit for semi-solid forming.

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

    Energy Technology Data Exchange (ETDEWEB)

    TEMPLETON, A.M.

    1999-12-07

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

  7. Laser welding of AZ61 magnesium-based alloys

    Institute of Scientific and Technical Information of China (English)

    Wang Hongying; Li Zhijun; Zhang Yihui

    2006-01-01

    Laser welding of AZ61 magnesium alloys was carried out asing a CO2 laser weldingexperimental system.The welding properties of AZ61 sheets with different thickness were investigated.The effect of processing parameters including laser power, welding speed and protection gas flow was researched.The results show that laser power and welding speed have large effect on the weld width and joint dimensions.Protection gas flow has relatively slight effect on the weld width.The property test of three typical joints indicates that microhardness and tensile strength in weld zone are higher than that of AZ61 base metal.Joints with good appearance and excellent mechanical properties can be produced using CO2 laser welding method.The microstructure with small grains in weld zone is believed to be responsible for the excellent mechanical properties of AZ61 joints.

  8. 78 FR 3877 - Radio Broadcasting Services; Peach Springs, AZ

    Science.gov (United States)

    2013-01-17

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 73 Radio Broadcasting Services; Peach Springs, AZ AGENCY: Federal Communications..., Radio broadcasting. Federal Communications Commission. Nazifa Sawez, Assistant Chief, Audio...

  9. 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...

  10. EnviroAtlas - Phoenix, AZ - Atlas Area Boundary

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset shows the boundary of the Phoenix, AZ Atlas Area. It represents the outside edge of all the block groups included in the EnviroAtlas Area....

  11. Hot Deformation Kinetics of Magnesium Alloy AZ31

    Institute of Scientific and Technical Information of China (English)

    WANG Lingyun; HUANG Guangjie; FAN Yonge; LU Zhiwen; PAN Fusheng

    2006-01-01

    The flow stress at elevated temperatures for magnesium alloy AZ31 was studied using isothermal compression testing. The effect of deformation parameters on the flow stress was studied as well. The kinetics of elevated temperature deformation was expressed by means of some empirical rate equations. The activation parameter has been calculated. A mechanism for the dynamic softening of AZ31 alloy in a hot deformation experiment was identified to be the dynamic recrystallization.

  12. Test Plan for Tank 241-AZ-101 Solubility Screening Tests

    Energy Technology Data Exchange (ETDEWEB)

    PERSON, J.C.

    1999-12-03

    Tank 241-AZ-101 (101-AZ) has been identified as one of the early tanks to be retrieved for waste pretreatment and immobilization. Retrieval of the tank waste from other tanks may require dilution. This test is to determine the effects of dilution on the mass of solids and their composition, which can be compared with tanks where dilution is required. This test plan gives test instructions, example data sheets, a waste compatibility review, and a waste stream fact sheet.

  13. Microstructure and Tensile Properties of AZ31B Alloy and AZ31B-SiCp Deformed Through a Multi-step Process

    Science.gov (United States)

    Shen, M. J.; Wang, X. J.; Ying, T.; Zhang, M. F.; Wu, K.

    2016-10-01

    The 15 vol.% micron SiC particle (SiCp)-reinforced AZ31B magnesium matrix composite (AZ31B-SiCp) prepared with semisolid stirring-assisted ultrasonic vibration was subjected to a multi-step process. The influence of the multi-step processing route on the microstructure and mechanical properties of the AZ31B-SiCp was investigated. For comparison, the monolithic AZ31B alloy was also processed under the same conditions. The results showed that the grain sizes of the AZ31B alloy and the AZ31B-SiCp were gradually decreased with increasing the processing step. Compared with the AZ31B-SiCp, the grain size of the AZ31B alloy was much larger, and the grain size distribution was inhomogeneous at the same processing condition. The particles of the AZ31B-SiCp were dispersed uniformly through the multi-step processing. Moreover, the tensile properties of the materials were gradually improved with increasing the processing step. In particular, the strength of AZ31B-SiCp and the ductility of AZ31B alloy improved significantly based on the room-temperature tensile test results.

  14. Improvement of wear resistance of AZ31 and AZ91HP by high current pulsed electron beam treatment

    Institute of Scientific and Technical Information of China (English)

    GAO Bo; HAO Sheng-zhi; DONG Chuang; TU Gan-feng

    2005-01-01

    The surface modification of magnesium alloys (AZ31 and AZ91HP) was studied by a high current pulsed electron beam(HCPEB). The results show that the cross-sectional microhardness of treated samples increases not only in the heat affected zone(HAZ), but also beyond HAZ, reaching over 250 μm. This is due to the action of quasi-static thermal stress and the shock thermal stress wave with materials, which result in its fast deformation on the surface layer and so increases microhardness. For the AZ91HP alloy, a nearly complete dissolution of the intermetallic phase Mg17Al12 is observed, and a super-saturated solid solution forms on the re-melted surface, which is due to the solute trapping effect during the fast solidification process. Measurements on sliding wear show that wear resistance is improved by approximately 5.6 and 2.4 times for the AZ31 and AZ91HP respectively, as compared with as-received samples.

  15. Environmentally friendly anodization on AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A novel anodization which is environmentally friendly,low voltage and lOW energy consumption was developed to improve corrosion resistance of AZ31 magnesium alloy.The corrosion resistance of the anodic films was studied by electrochemical impedance spectroscopy(EIS)and potentiodynamic polarization techniques.The microstructure and compositions of films were examined by SEM,XPS and XRD.A new kind of organic additive used in the electrolyte is friendly to the environment.The compact,intact and uniform coating with high hardness can be prepared on AZ31 magnesium alloy by the environmentally friendly anodization,which enhances the corrosion resistance of AZ31 Mg alloy significantly.

  16. Annealing behavior of rolled AZ31 alloy sheet

    Institute of Scientific and Technical Information of China (English)

    PENG Wei-ping; LI Pei-jie; ZENG Pan

    2006-01-01

    The annealed microstructures of the rolled AZ31 alloy sheets were examined by using light optical microscopy. The mechanical properties were measured by tensile testing, with their crystal orientations analyzed by X-ray diffraction (XRD). After the annealing treatment, the elongated grains were transformed to equiaxed grains with uniform and homogeneous structures. The changes of microstructure decreased the yield strength and enhanced the elongation. The analysis of XRD shows that the AZ31 alloy sheet possesses intense basal-texture, which is weakened during the recrystallization while reinforced during the grain growth. The intense basal-texture induces low ductility, which hence makes the further rolling more difficult. The results indicate that the optimum annealing treatment during AZ31 alloys sheet rolling is at about 300 ℃ for 60-120 min.

  17. Preliminary study of biodegradation of AZ31B magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    REN Yibin; HUANG Jingjing; ZHANG Bingchun; YANG Ke

    2007-01-01

    Magnesium alloys are potential to be developed as a new type of biodegradable implant material by use of their active corrosion behavior.Both in vitro and in vivo biodegradation properties of an AZ31B magnesium alloy were investigated in this work.The results showed that AZ31B alloy has a proper degradation rate and much lower hydrogen release in Hank's solution,with a degradation rate of about 0.3 mm/year and hydrogen release below 0.15mL/cm2.The animal implantation test showed that the AZ31B alloy could slowly biodegrade in femur of the rabbit and form calcium phosphate around the alloy sample,with the Ca/P ratio close to the natural bone.

  18. Data of evolutionary structure change: 1AZ5A-1HTGA [Confc[Archive

    Lifescience Database Archive (English)

    Full Text Available 1AZ5A-1HTGA 1AZ5 1HTG A A PQFHLWKRPVVTAHIEGQPVEVLLDTGADDSIVTGIELG...PHYTPKIV----GFINTKEYKNVEVEVLGKRIKGTIMTGDTPINIFGRNLLTALGMSLNF PQITLWQRPLVTIKIGGQLKEALLDTGADDTVLE...THR CA 318 1HTG A 1HTGA

  19. 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.

  20. AZ91C magnesium alloy modified by Cd

    DEFF Research Database (Denmark)

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

    2014-01-01

    In the present work, the effect of Cd on the microstructure, mechanical properties and general corrosion behaviour of AZ91C alloys was investigated. Addition of Cd was found not to be efficient in modifying/refining the microstructure or β-phase. A morphology change in β-phase from fine continuou...

  1. 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..., allots FM Channel 281C3 at Peach Springs, Arizona, in order to maintain a first local service at that community. Channel 281C3 can be allotted at Peach Springs, Arizona, in compliance with the...

  2. Accretion Events in Binary Systems: AZ Cas and VV Cep

    CERN Document Server

    Gałan, C; Tomov, T; Wiȩcek, M; Majcher, A; Wychudzki, P; Świerczyński, E; Kolev, D; Brożek, T; Maciejewski, G; Zoła, S; Kurpińska-Winiarska, M; Winiarski, M; Ogłoza, W; Drożdż, M; Krzesiński, J

    2011-01-01

    The sudden lengthening of orbital period of VV Cep eclipsing binary by about 1% was observed in the last epoch. The mass transfer and/or mass loss are most possible explanations of this event. The photometric behaviour of AZ Cas, the cousin of VV Cep, suggests that the accretion can occur and could be important in this system, too.

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

    Energy Technology Data Exchange (ETDEWEB)

    Gu, X N; Zheng, Y F [State Key Laboratory for Turbulence and Complex System and Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Chen, L J, E-mail: yfzheng@pku.edu.c [School of Material Science and Engineering, Shengyang University of Technology, Shenyang 110023 (China)

    2009-12-15

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

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

    Science.gov (United States)

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

    2009-12-01

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

  5. Tube extrusion of AZ31 alloy with Sr additions

    Energy Technology Data Exchange (ETDEWEB)

    Sadeghi, Alireza, E-mail: Alireza.Sadeghi@mail.mcgill.ca [McGill University, Department of Mining and Materials Science, Montreal, Quebec (Canada); Hoseini, Majid; Pekguleryuz, Mihriban [McGill University, Department of Mining and Materials Science, Montreal, Quebec (Canada)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Bending and unbending of material flow during extrusion tilts the basal pole from the center of the pole figure. Black-Right-Pointing-Pointer Circumferential movement of material inside the welding zone forms two extra texture components. Black-Right-Pointing-Pointer Addition of Sr removes Al from {alpha}-Mg as a result grains could deform more easily in the circumferential directions. Black-Right-Pointing-Pointer By increasing level of Sr, maximum intensity of the ODFs decreases while the extra texture components strengthen. - Abstract: Three Mg alloys (AZ31, and AZ31 + 0.4 and 0.8 wt%Sr) were successfully hot extruded into tubes at 400 Degree-Sign C through a porthole die. Strontium (Sr) additions to AZ31 alloy reduced twining and the dynamically recrystallized grain size. However, Sr also increased the surface cracking tendency during extrusion. It was noted that the complex deformation path in the porthole die distributes the Sr-rich precipitates homogeneously across the microstructure and stringer formation is effectively avoided. The material flow in the die resembles that seen in multiple equal channel angular pressing (ECAP) routes and similar and significant effects on the final texture are observed. The material flow curvatures in the extrusion direction rotate the basal poles 25 Degree-Sign from the radial direction. Two other texture components ({delta}{sub 1}, {delta}{sub 2}) are also formed in the welding zone by the circumferential flow of material. The maximum intensity of the orientation distribution function (ODF) is reduced with increasing level of Sr. Noteworthy, the maximum intensity in AZ31 + 0.8Sr occurs at the {delta}{sub 1} component while for AZ31 and AZ31 + 0.4Sr, the maximum intensity is located at the basal components. With Sr, alloying, Al is depleted from Mg solid solution and grains deform more easily in the circumferential direction. As a result, selective workhardening

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

    Science.gov (United States)

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

    2016-07-20

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

  7. Investigation on hot deformation behavior of AZ31 madnesium alloy

    Institute of Scientific and Technical Information of China (English)

    汪凌云; HUANG; Guangsheng; 等

    2002-01-01

    The hot compressive deformation of extruded AZ31 magnesium alloy with the mass fractions of Al and Zn equal to 3%and 1% respectively is studied by a Gleeble-1500D thermal mechanical simulator over the temperature range from 200℃to 400℃ and the strain rate from 10-3 s-1 to 100s-1.The true stress-strain curves of the strain of 65% are tested.The deformation activation energy is obtained and the flow stress model is established by analyzng the effects of strain rate and temperature on the flow stress.Zener-Hollomon parameter is introduced to describe the softening behaviors of AZ31 magnesium alloy resulted from dynamic recrystallization during the hot compressive deformation,whose natural logarithm is linear with the critical strain of dynamic recrystallization.

  8. MICROSTRUCTURAL STUDIES OF FRICTION STIR WELDED AZ31 MAGNESIUM ALLOY

    Institute of Scientific and Technical Information of China (English)

    H.Zhang; S.B.Lin; L.Wu; J.C.Feng

    2004-01-01

    Friction stir welding achieves the weld in solid phase by locally introducing frictional heating and plastic flow arising from rotation of the welding tool, which results in changes in the local microstructure of magnesium alloy. The purpose in the paper is to study the microstructures of friction stir welded AZ3I magnesium alloy. Residual microstructures,including dynamic re-crystallization zone and nugget structures have been systematically investigated utilizing optical microscopy (OM), scanning electric microscopy (SEM),transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and micro-hardness. AZ31 magnesium alloy has been successfully friction stir welded and exhibits the variations of microstructure including dynamically recrystallized,equaxied grains in the weld nugget. Residual hardness in the nugget was found slightly lower than the parent but not too obvious.

  9. The Formablity of AZ31B Magnesium Alloy Sheet

    Institute of Scientific and Technical Information of China (English)

    WANG Lingyun; LU Zhiwen; ZHAO Yazhong; QIU Xiaogang

    2006-01-01

    The forming limit diagrams(FLD)of AZ31B magnesium alloy sheet were tested by means of the electro etching grid method based on the forming experiment of magnesium alloy sheet carried out with a BCS-30D sheet forming testing machine and the strain testing analysis made with an advanced ASAME automatic strain measuring system. Experiments show that, at room temperature, the mechanical properties and deep drawing performance of AZ31B cold-rolled magnesium alloy sheet were so poor that it failed to test the forming limit diagrams without an ideal forming and processing capacity, while the hot-rolled magnesium alloy sheet was of a little better plasticity and forming performance after testing its forming limit diagrams. It can be concluded that the testing of the forming limit curves (FLC)offers the theoretical foundation for the drawing of the deep drawing and forming process of magnesium alloy sheet.

  10. Rheo-diecasting of AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    XU Jun; LIU Guojun; ZHANG Shaoming; SHI Likai; FAN Zhongyun

    2010-01-01

    A rheo-diecasting process(RDC)was investigated for semisolid processing of an AZ91D magnesium alloy.The results of the RDC samples in as-cast state indicate that the microstructure of primary ct-Mg particles has a fine size,nearly spherical morphology,and uniform distribution throughout the components.Due to the advanced microstructure and reduced level of defects,the RDC AZ91D Mg alloy exhibits an apparent improvement in mechanical properties.The quantitative metallographic investigations reveal that increasing the intensity of forced convection during the slurry preparation results in a promoted nucleation and reduced volume fraction of the primary phase solidified in the slurry makor.

  11. Study on Bamboo Treatment Technology with CuAz Preservative

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In order to research the effect of preservative penetrability, CuAz (copper azole) was used for the preservative, and pieces of Moso bamboo (Phyllostachys pubescens) were used for the experimental materials in this study. The vacuum pressure process was used to treat bamboo pieces. The results showed as follows: 1) Main treatment factors were preservative concentration and applied pressure; 2) In the same technology, both the retention and the weight proportion gain of the samples without node were less tha...

  12. Microstructures of AZ91D alloy solidified during electromagnetic stirring

    Institute of Scientific and Technical Information of China (English)

    MAO Wei-min; ZHEN Zi-sheng; CHEN Hong-tao

    2005-01-01

    With the help of an electromagnetic stirring device self-made and alloy melt quenching technology,the effect of electromagnetic stirring parameters on the microstructures of semi-solid AZ91D alloy was mainly studied at the stirring frequency of 200 Hz.The experimental results show that when the stirring power rises,the primary α-Mg rosettes in the semi-solid melt will bear stronger man-made temperature fluctuation and the root remelting effect of the dendritic arms is promoted so that the spherical primary α-Mg grains become much more and rounder.If the stirring frequency is 200 Hz,the ideal semi-solid microstructure of AZ91D magnesium alloy can be obtained when the stirring power is increased to 6.0 kW.If the stirring frequency is 200 Hz and the stirring power is 6.0 kW,it is found that the lower cooling rate is favorable for the spherical primary α-Mg grains to be developed during the electromagnetic stirring stage.If the AZ91D magnesium alloy billet prepared during electromagnetic stirring at the stirring frequency of 200 Hz and the stirring power of 6.0 kW is reheated to the solidus and liquidus temperature region,the primary α-Mg grain's shape will get more spherical,so it is very advantageous to the semi-solid thixoforming process.

  13. Microstructures and mechanical properties of AZ80 alloy treated by pulsed ultrasonic vibration

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Pulsed ultrasonic field was employed in the melt of the AZ80 magnesium alloy. The effects of pulsed ultrasonic field on mierostructure and mechanical properties of AZ80 magnesium alloy were investigated. The results show that the as-cast mierostructure of the AZ80 alloy with pulsed ultrasonic treatment is significantly changed. Pulsed ultrasonic field significantly decreases the grain size, changes the morphologies of the β-Mg17Al12 phases and reduces their area fraction. It is found that pulse width of ultrasonic plays an important role on the microstrueture formation of AZ80 alloy. With increasing pulse width, grains beeome finer and more uniform. In the range of experimental parameters, the optimum pulse width for melt treatment process is found to be 210 μs. The mechanical tests show that the mechanical properties of the as-cast AZ80 magnesium alloy with pulsed ultrasonic treatment are much higher than those of AZ80 alloy without ultrasonic field.

  14. 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.

  15. 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

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

    Science.gov (United States)

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

    2008-03-01

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

  17. 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.

  18. Thermomechanical Processing and Superplasticity of AZ91 Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    Rongshi CHEN; J.J. Blandin; M.Suéry; Qudong WANG; Enhou HAN

    2004-01-01

    The effect of extrusion on grain refinement has been studied in the AZ91 cast ingots. It is found that grain size smaller than 10 μm can be obtained by the extrusion processing. Vickers hardness measurements were also carried out to evaluate the effect of these processes on the room temperature mechanical properties. The experimental results of high temperature tensile tests revealed that the stress was inversely proportional to the square of the grain size and that the activation energy for superplastic flow was higher than that for grain boundary diffusion.

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

    Science.gov (United States)

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

    2016-02-09

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

  20. 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....

  1. 76 FR 3570 - Proposed Amendment of Class E Airspace; Taylor, AZ

    Science.gov (United States)

    2011-01-20

    ... Federal Aviation Administration 14 CFR Part 71 Proposed Amendment of Class E Airspace; Taylor, AZ AGENCY... action proposes to modify Class E airspace at Taylor Airport, Taylor, AZ. Controlled airspace is necessary to accommodate aircraft using the CAMBO One Departure Area Navigation (RNAV) out of Taylor...

  2. 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

  3. 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

  4. 77 FR 2241 - Radio Broadcasting Services; Ehrenberg, First Mesa, Kachina Village, Wickenburg, and Williams, AZ...

    Science.gov (United States)

    2012-01-17

    ... COMMISSION 47 CFR Part 73 Radio Broadcasting Services; Ehrenberg, First Mesa, Kachina Village, Wickenburg, and Williams, AZ; and Application of Univision Radio License Corporation, KHOV-FM, Wickenburg, AZ... by Rocket Radio, Inc., proposes the allotment of FM Channel 287C2 at Williams, Arizona, as...

  5. Sintered AZS Bricks for Glass Melting Furnace JC/T 925-2003

    Institute of Scientific and Technical Information of China (English)

    Yu Lingyan; Chai Junlan

    2009-01-01

    @@ 1 Scope This standard specifies the brand,technical requirements,test methods,inspection rules,marking,packing,transportation,storage,and quality certificate of sintered AZS bricks for glass melting furnace.This standard is applicable to sintered AZS bricks for glass melting furnace.

  6. 78 FR 78298 - Proposed Establishment of Class E Airspace; Phoenix, AZ

    Science.gov (United States)

    2013-12-26

    ... Federal Aviation Administration 14 CFR Part 71 Proposed Establishment of Class E Airspace; Phoenix, AZ... proposed rulemaking (NPRM). SUMMARY: This action proposes to establish Class E airspace at the Phoenix VHF Omni-Directional Radio Range Tactical Air Navigation Aid (VORTAC), Phoenix, AZ, to facilitate...

  7. Influence of hot extrusion on microstructure and mechanical properties of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    WANG Ling; TIAN Su-gui; MENG Fan-lai; DU Hong-qiang

    2006-01-01

    Extrusion treatment is a common method to refine the grain size and improve the mechanical properties of metal material. The influence of hot extrusion on microstructure and mechanical properties of AZ31 magnesium alloy was investigated. The results show that the mechanical properties of AZ31 alloy are obviously improved by extrusion treatment. The ultimate tensile strength (UTS) of AZ31 alloy at room temperature is measured to be 222 MPa, and is enhanced to 265.8 MPa after extrusion at 420℃. The yield tensile strength (YTS) of AZ31 alloy at room temperature is measured to be 84 MPa, and is enhanced to 201 MPa after extrusion at 420℃. The effective improvements on mechanical properties result from the formation of the finer grains during extrusion and the finer particles precipitated by age treatment. The features of the microstructure evolution during hot extruded of AZ31 alloy are dislocation slipping on the matrix and occurrence of the dynamic recrystallization.

  8. Effects of rare earth elements on the microstructure and properties of magnesium alloy AZ91D

    Institute of Scientific and Technical Information of China (English)

    KaikunWang; KuiZhang; 等

    2002-01-01

    The effects of rare earth elements on the microstructure and properties of Magnesium alloy AZ91D alloy were studied.The different proportion of rare earth elements was added to the AZ91D and the tensile tests were carried out at different temperatures.The experimental results show that at room temperature or at 120℃ the AZ91D's decrease with the increasing amount of the rare earth elements.however,the ductility is improved.The influence of 0.14%Sb(mass fraction)on the AZ91D's strength is like that of rare earth elements(0.2%-0.4%)(mass fraction).Microstructure graphs demonstrate that appropriate amount of rare earth elements (0.1%-0.2%) can fine AZ91D's grain and improve its ductility.

  9. Effects of rare earth elements on the microstructureand properties of magnesium alloy AZ91D

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effects of rare earth elements on the microstructure and properties of magnesium alloy AZ91D alloy were studied. The different proportion of rare earth elements was added to the AZ91D and the tensile tests were carried out at different temperatures. The experimental results show that at room temperature or at 120℃ the AZ91D's strength decrease with the increasing amount of the rare earth elements. However, the ductility is improved. The influence of 0.14%Sb (mass fraction) on the AZ91D's strength is like that of rare earth elements (0.2%-0.4%) (mass fraction). Microstructure graphs demonstrate that appropriate amount of rare earth elements (0.1%-0.2%) can fine AZ91D's grain and improve its ductility.

  10. Recrystallization in AZ31 magnesium alloy during hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Essadiqi, E.; Liu, W.J.; Kao, V. [Natural Resources Canada, Materials Technology Lab., CANMET, Ottawa, ON (Canada); Yue, S. [Dept. of Metallurgical Engineering, McGill Univ., Montreal, PQ (Canada); Verma, R. [General Motors, Materials and Processes Lab, Warren, MI (United States)

    2005-07-01

    In this study, isothermal torsion tests were carried out on magnesium AZ31B alloy under constant strain rate conditions, in the range of 250 to 400 C at 0.01, 0.1, and 1.0 s{sup -1}. Alloy flow stress dependence on strain rate and temperature can be described by a power law with activation energy of 130 kJ/mol. Microstructural examination of hot deformed samples shows very fine recrystallized grains decorating grain boundaries of larger gains in the form of a necklace. These fine grains are produced by dynamic recrystallization at the grain boundaries of original grains. Microstructure evolution, based on samples quenched at different strain levels, indicates that increasing deformation strain has little effect on recrystallized grain size but widens the recrystallized region, with full recrystallization achieved at a certain high strain level. Recrystallized grain size increases with increasing deformation temperature and strain rate. The latter suggests recrystallization in AZ31 to be essentially a time dependant phenomenon. (orig.)

  11. Examination of dynamic recrystallization during compression of AZ31 magnesium

    Institute of Scientific and Technical Information of China (English)

    XIN RenLong; WANG BingShu; CHEN XingPin; HUANG GuangJie; LIU Qing

    2009-01-01

    This study aimed to investigate dynamic recrystallization (DRX) behavior during compression of mag-nesium alloy AZ31. Cylinder samples were cut from the extruded rod and hot rolled sheet AZ31 for compression test. The samples were compressed using a Gleeble 1500D at a temperature of 300Ⅱ and a strain rate of 0.01 s-1. Grain orientations and misorientation angles across grain boundaries for the tested samples were obtained by using electron backscatter diffraction (EBSD) technique. The results showed that strong basal texture was observed after 50% compression (ε = 0.69) on both the extruded and hot rolled samples, which have different initial textures. It was observed that with increased strain, DRX grains gradually rotated to basal orientation, and grain boundaries with misorientation angle of near 30° was formed in the samples. At the strain of 0.69, a high fraction of high-angle (> 60°) bounda-ries was present in the extruded sample, whereas almost no high angle boundaries were observed in the hot rolled sheet sample.

  12. Examination of dynamic recrystallization during compression of AZ31 magnesium

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This study aimed to investigate dynamic recrystallization (DRX) behavior during compression of magnesium alloy AZ31. Cylinder samples were cut from the extruded rod and hot rolled sheet AZ31 for compression test. The samples were compressed using a Gleeble 1500D at a temperature of 300℃ and a strain rate of 0.01 s-1. Grain orientations and misorientation angles across grain boundaries for the tested samples were obtained by using electron backscatter diffraction (EBSD) technique. The results showed that strong basal texture was observed after 50% compression (ε = 0.69) on both the extruded and hot rolled samples, which have different initial textures. It was observed that with increased strain, DRX grains gradually rotated to basal orientation, and grain boundaries with misorientation angle of near 30° was formed in the samples. At the strain of 0.69, a high fraction of high-angle (> 60°) bounda-ries was present in the extruded sample, whereas almost no high angle boundaries were observed in the hot rolled sheet sample.

  13. Dynamic recrystallization behavior of AZ61 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hai-tao; YAN An-qing; LIU Chu-ming

    2005-01-01

    An AZ61 alloy was subjected to hot compression at temperatures ranging from 523 K to 673 K,with strain rates of 0. 001 - 1 s-1. Flow softening occurs at all temperatures and strain rates. There are peak and plateau stresses on flow curves. The initiation and evolution of dynamic recrystallization(DRX) were studied by the flow softening mechanism based on the flow curves and microstructural observations. A linear relationship was established between the logarithmic value of the critical strain for DRX initiation(lnεc) and the logarithmic value of the Zener-Hollomon parameter (lnZ). The volume fraction of DRX grain (ψd) is formulated as a function of the process parameters including strain rate, temperature, and strain. The calculated values of ψd agree well with the values extracted from the flow curves. The size of DRX grain(d) was also formulated as a function of the ZenerHollomon parameter. This study suggests that DRX behavior of AZ61 can be predicated from plastic process parameters.

  14. 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.

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

    Science.gov (United States)

    Zou, Jian; Xu, Hongwei; Li, Xiaolin

    2017-01-01

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

  16. AZ31和AZ91镁合金等温挤压及挤压后的微观组织变化%The isothermal extrusion and the microstructure evolution after extrusion of AZ31 and AZ91 magnesium

    Institute of Scientific and Technical Information of China (English)

    李洪波; 吕玫; 马文昌

    2011-01-01

    The extrusion property and microstructure evolution of AZ31 and AZ91 magnesium alloy under different deformation conditions were studied in isothermal extrusion process and through metallographic examination. The results show that the form-ing quality of AZ31 magnesium alloy is better than AZ91 magnesium alloy. For AZ91, the cracks would appear on the specimen surface at extrusion ratio 4:1, extrusion temperature 400℃, and at extrusion ratio 9 :1, extrusion temperature 350℃ and 400℃. The best forming temperature for AZ31 is 300℃~400℃, for AZ91 is 300℃~350℃. Dynamic recrystallization occurred in the hot extrusion process of the magnesium alloy, the grain of extruded samples were significantly refined.%通过等温挤压和金相观察,研究了AZ31和AZ91镁合金不同变形条件下的挤压性能和变形后的微观组织变化.结果表明,AZ31镁合金的挤压变形性能较好,而AZ91镁合金在挤压比为4∶1、挤压温度为400℃,以及在挤压比为9∶1、挤压温度为350℃和400℃时,挤压后的试件表面均出现了裂纹;AZ31镁合金的最佳成形温度为300℃~400℃,AZ91镁合金的最佳成形温度为300℃~350℃;镁合金在热挤压过程中发生了动态再结晶,挤压之后合金的晶粒显著细化.

  17. Ba isotopic signature for early differentiation between Cs and Ba in natural fission reactors

    Science.gov (United States)

    Hidaka, Hiroshi; Gauthier-Lafaye, François

    2008-08-01

    Ba isotopic studies of the Oklo and Bangombé natural fission reactors in east Gabon provide information on the geochemical behavior of radioactive Cs ( 135Cs and 137Cs) in a geological medium. Large isotopic deviations derived from fissiogenic Ba were found in chemical leachates of the reactor uraninites. The fissiogenic Ba isotopic patterns calculated by subtracting the non-fissiogenic component are classified into three types that show different magnifications of chemical fractionation between Cs and Ba. In addition, the isotopic signatures of fissiogenic 135Ba, 137Ba and 138Ba suggest an early differentiation between Cs and Ba of less than 20 years after the production of fissiogenic Cs and Ba. On the other hand, only small excesses of 135Ba ( ɛ < +1.8) and/or 137Ba ( ɛ < +1.3) were identified in some clay samples, which might have resulted from selective adsorption of 135Cs and 137Cs that migrated from the reactors by differentiation.

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

    Science.gov (United States)

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

    2016-06-01

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

  19. Crystal structures of heterotypic nucleosomes containing histones H2A.Z and H2A.

    Science.gov (United States)

    Horikoshi, Naoki; Arimura, Yasuhiro; Taguchi, Hiroyuki; Kurumizaka, Hitoshi

    2016-06-01

    H2A.Z is incorporated into nucleosomes located around transcription start sites and functions as an epigenetic regulator for the transcription of certain genes. During transcriptional regulation, the heterotypic H2A.Z/H2A nucleosome containing one each of H2A.Z and H2A is formed. However, previous homotypic H2A.Z nucleosome structures suggested that the L1 loop region of H2A.Z would sterically clash with the corresponding region of canonical H2A in the heterotypic nucleosome. To resolve this issue, we determined the crystal structures of heterotypic H2A.Z/H2A nucleosomes. In the H2A.Z/H2A nucleosome structure, the H2A.Z L1 loop structure was drastically altered without any structural changes of the canonical H2A L1 loop, thus avoiding the steric clash. Unexpectedly, the heterotypic H2A.Z/H2A nucleosome is more stable than the homotypic H2A.Z nucleosome. These data suggested that the flexible character of the H2A.Z L1 loop plays an essential role in forming the stable heterotypic H2A.Z/H2A nucleosome.

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

    Science.gov (United States)

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

    2016-05-01

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

  1. On the deformation twinning of Mg AZ31B

    DEFF Research Database (Denmark)

    Abdolvand, Hamidreza; Majkut, Marta; Oddershede, Jette

    2015-01-01

    variants was non-negligible. The CPFE simulation indicates that there is a small variation in the stress within each grain in the elastic regime, which increases drastically upon the onset of plasticity. One of the significant outcomes of this work is the new statistical information on the interaction......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...

  2. Friction stir welding of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    林三宝; 张华; 吴林; 冯吉才; 戴鸿滨

    2003-01-01

    Friction stir welding (FSW) is an new solid-phase joining technology which has more advantages over fusion welding methods in welding of aluminum and other non-ferrous metals. The effects of welding parameters on mechanical properties and microstructure during friction stir welding of AZ31 magnesium alloy were studied in this paper. Microstructures and mechanical properties of the joints were investigated by means of optical microscopy, scanning electric microscopy (SEM), micro-hardness analysis, and tensile test. Experimental results show that the magnesium alloy can be successfully welded by FSW method, and the ultimate tensile strength (UTS) of FSW joint reaches up to 90 percent of base metal. The microstructures of welded joints exhibit the variation from dynamically recrystallized fine grains to greatly deformed grains. Hardness in nugget zone was found lower than the base metal but not too obvious.

  3. Grain refinement in magnesium alloy AZ31 during hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Yang Xuyue; Miura, H.; Sakai, T. [Dept. of Mechanical Engineering and Intelligent Systems, Univ. of Electro-Communications, Chofu, Tokyo (Japan)

    2004-07-01

    The deformation behavior and structure changes of magnesium alloy AZ31 were studied in compression at temperatures ranging from 523 K to 673 K and at a strain rate of 3 x 10{sup -3} s{sup -1}. They depend sensitively on deformation temperature. At high temperatures, grain fragmentation takes place due to frequent formation of kink bands initially at corrugated grain boundaries and then in grain interiors, followed by full development of new grains in high strain. At lower temperatures, in contrast, twinning takes place in rather coarse grains and kink bands are formed mainly in finer original ones in low strain. It is concluded that new grain evolution can be controlled by a deformation-induced continuous reaction resulting in grain fragmentation by kink bands, i.e. continuous dynamic recrystallization (cDRX). The latter is discussed comparing with conventional, i.e. discontinuous, DRX. (orig.)

  4. Fretting wear behavior of AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN An-hua; HUANG Wei-jiu; LI Zhao-feng

    2006-01-01

    The fretting behaviour of the AZ91D magnesium alloy was investigated. The influence of the number of cycles, normal load (contact pressure) and the amplitude of slip on the fretting behavior of the material were focused. Fretting tests were performed under various running conditions with regard to normal load levels and slip amplitudes. The friction coefficient between the surfaces at the fretting junction was continuously recorded. The fretting damage on the magnesium specimens was studied by SEM. The results show that the wear volume increases with the increase of slip amplitude, and linearly increases with the increase of normal load in the mixed and gross slip regime, but the normal load has no obvious effect on the wear volume in the partial slip regime. The predominant fretting wear mechanism of magnesium alloy in the slip regime is the oxidation wear, delaminated wear and abrasive wear.

  5. Application of AZ4903 to production of stator windings

    Institute of Scientific and Technical Information of China (English)

    Zhanshe GUO; Yihui WU; Yonggang MENG; Dezhi ZHENG

    2008-01-01

    To satisfy the needs of the high deep-width ratio and thickness of a planar micromotor's stator windings, a process method to produce an electromag-netic planar micromotor with AZ4903 is proposed. Optimum relationships, such as the desired rotation speed vs. thickness of the coating process, and the temperature vs. time of pre-baking, are obtained. The appropriate time of lithography and development are also achieved. The thickness of the produced windings is 40 μm with ideal perpendicularity. Finally, stators and rotors are fabricated. The rotation speed and pull-out torque of the micromotor are tested. The experiment proved that the micromotor worked with a steady speed and a low ripple of pull-out torque.

  6. Influence of deformation on precipitation in AZ80 magnesium alloy

    Science.gov (United States)

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

    2011-06-01

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

  7. Microstructural stability after severe plastic deformation of AZ31 Magnesium

    Science.gov (United States)

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

    2014-08-01

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

  8. Telomeric heterochromatin boundaries require NuA4-dependent acetylation of histone variant H2A.Z in Saccharomycescerevisiae

    Science.gov (United States)

    Babiarz, Joshua E.; Halley, Jeffrey E.; Rine, Jasper

    2006-01-01

    SWR1-Com, which is responsible for depositing H2A.Z into chromatin, shares four subunits with the NuA4 histone acetyltransferase complex. This overlap in composition led us to test whether H2A.Z was a substrate of NuA4 in vitro and in vivo. The N-terminal tail of H2A.Z was acetylated in vivo at multiple sites by a combination of NuA4 and SAGA. H2A.Z acetylation was also dependent on SWR1-Com, causing H2A.Z to be efficiently acetylated only when incorporated in chromatin. Unacetylatable H2A.Z mutants were, like wild-type H2A.Z, enriched at heterochromatin boundaries, but were unable to block spreading of heterochromatin. A mutant version of H2A.Z that could not be acetylated, in combination with a mutation in a nonessential gene in the NuA4 complex, caused a pronounced decrease in growth rate. This H2A.Z mutation was lethal in combination with a mutant version of histone H4 that could not be acetylated by NuA4. Taken together, these results show a role for H2A.Z acetylation in restricting silent chromatin, and reveal that acetylation of H2A.Z and H4 can contribute to a common function essential to life. PMID:16543222

  9. Influence of neodymium on high cycle fatigue behavior of die cast AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    杨友; 李雪松

    2010-01-01

    High cycle fatigue behavior of die cast AZ91D magnesium alloy with different Nd contents was investigated.Axial mechanical fatigue tests were conducted at the stress ratio R=0.1 and the fatigue strength was evaluated using up-to-down load method on specimens of AZ91D with different Nd contents.The results showed that the grain of AZ91D alloy was refined,the size and amount of β-Mg17Al12 phase decreased and distributed uniformly with increasing Nd content.At the number of cycles to failure,Nf=107,the fatigue...

  10. Simulation of Magnesium Alloy AZ91D Microstructure Using Modified Cellular Automaton Method

    Institute of Scientific and Technical Information of China (English)

    HUO Liang; LI Bin; SHI Yufeng; XU Qingyan; HAN Zhiqiang; LIU Baicheng

    2009-01-01

    A two-dimensional modified cellular automaton model was developed to simulate the solidification process of magnesium alloy, The stochastic nucleation, solute redistribution, and growth anisotropy effects were taken into account in the present model. The model was used to simulate the grain size of magnesium alloy AZ91D for various cooling rates during the solidification process. To quantitatively validate the current model, metallographic expedments were carded out on specimens obtained from sand mold AZ91D step castings. The metallographic results agree well with the prediction results. The current model can be used to accurately predict the grain sizes of cast AZ91D magnesium alloy.

  11. Thermal fatigue of magnesium-base alloy AZ91; Zur thermischen Ermuedung der Magnesium-Basislegierung AZ91

    Energy Technology Data Exchange (ETDEWEB)

    Krauss, M.; Scholtes, B. [Institut fuer Werkstofftechnik - Metallische Werkstoffe, Universitaet Kassel (Germany)

    2008-08-15

    Thermal fatigue tests of the magnesium-base alloy AZ91 were carried out under total strain control and out-of-phase-loading conditions in a temperature range between -50 C and +190 C. Specimens produced by a vacuum die casting process were loaded under constant total strain and uniaxial homogeneous stress. To simulate the influence of different mean stresses, experiments were started at different temperature levels, e.g. the lower, mean or upper temperature of the thermal cycle. The thermal fatigue behavior is described by the resulting stress amplitudes, plastic strain amplitudes and mean stresses as a function of the number of thermal loading cycles. Depending on the maximum temperature and the number of loading cycles, cyclic softening as well as cyclic hardening behavior is observed. Due to the complex interaction of deformation, recovery and recrystallization processes and as a consequence of the individual temperature and deformation history, thermal fatigue processes of the material investigated cannot be assessed using results of isothermal experiments alone. The upper temperatures or the resp. temperature amplitudes determine the total fatigue lifetime. (Abstract Copyright [2008], Wiley Periodicals, Inc.) [German] Es wird ueber Ergebnisse von Untersuchungen zur thermischen Ermuedung der Mg-Gusslegierung AZ91 berichtet. Die im Vakuumdruckgussverfahren hergestellten Proben wurden bei Konstanthaltung der Totaldehnung unter einachsig-homogener Beanspruchung im Temperaturbereich zwischen -50 C und +190 C belastet. Die Versuche wurden bei unterschiedlichen Temperaturniveaus gestartet, so dass sich zu Beginn unterschiedliche Mittelbeanspruchungen einstellten. Das Werkstoffverhalten wird durch die resultierenden Spannungsamplituden, plastischen Dehnungsamplituden und Mittelspannungen charakterisiert. In Abhaengigkeit der Temperatur und der Lastspielzahl wird sowohl zyklische Entfestigung als auch Verfestigung beobachtet. Aufgrund der komplexen Wechselwirkungen

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

    Data.gov (United States)

    U.S. Environmental Protection Agency — 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...

  13. 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...

  14. Wear resistance of ceramic coating on AZ91 magnesium alloy by micro-arc oxidation

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui; LIU Zheng; CHEN Li-jia; CHEN Ji; HAN Zhong

    2006-01-01

    The ceramic coating formed on AZ91 magnesium alloy by micro-arc oxidation (MAO) was characterized. The results show that the ceramic coating(3.4-23 μm in thickness)on the surface of AZ91 alloy was attained under different micro-arc oxidation treatment conditions, which consist mainly of MgO, Mg2SiO4 and MgSiO3 phases. Nano-hardness in a cross-sectional specimen was determined by nano-indentation experiment. The MAO coatings exhibit higher hardness than the substrate. Dry sliding wear tests for the MAO coatings and AZ91 alloy were also carried out using an oscillating friction and wear tester in a ball-on-disc contact configuration. The wear resistance of the MAO coatings is improved respectively under different treatment time as a result of different structures of ceramic coatings formed on AZ91 alloy.

  15. 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...

  16. 78 FR 7391 - Motorized Travel Management Plan, Tonto National Forest; Gila, Maricopa, Pinal, and Counties, AZ

    Science.gov (United States)

    2013-02-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Forest Service Motorized Travel Management Plan, Tonto National Forest; Gila, Maricopa, Pinal, and Counties, AZ AGENCY: Forest Service, USDA. ACTION: Notice of intent to prepare an environmental...

  17. 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... Semiconductor, Inc., Technical Information Center, Tempe, Arizona. The notice was published in the...

  18. 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..., Inc., grantee of FTZ 277, requesting manufacturing authority on behalf of Suntech Arizona, Inc... foreign inputs that become scrap or waste during manufacturing. FTZ designation would further...

  19. Operational Test Report for the 241-AZ-101 Suspended Solids Profiler

    Energy Technology Data Exchange (ETDEWEB)

    STENKAMP, D.M.

    2000-04-03

    This document comprises the Operational Test Report for the 241-AZ-101 Suspended Solids Profiler. This document presents the results of Operational Testing of the 241-AZ-101 Suspended Solids Profiler (SSP). Testing of the SSP was performed in accordance with OTP-260-005, ''SUSPENDED SOLIDS PROFILER OPERATIONAL TEST PROCEDURE''. The objective of the testing was to verify that all equipment and components functioned as designed, following construction completion and turnover to operations.

  20. Determination of substrate log-normal distribution in the AZ91/SICP composite

    Directory of Open Access Journals (Sweden)

    J. Lelito

    2015-01-01

    Full Text Available The aim in this work is to develop a log-normal distribution of heterogeneous nucleation substrates for the composite based on AZ91 alloy reinforced by SiC particles. The computational algorithm allowing the restore of the nucleation substrates distribution was used. The experiment was performed for the AZ91 alloy containing 1 % wt. of SiC particles. Obtained from experiment, the grains density of magnesium primary phase and supercooling were used to algorithm as input data.

  1. Development of Rolling Schedules for Equal Channel Angular Extrusion (ECAE)-Processed AZ31 Magnesium Alloy

    Science.gov (United States)

    2016-04-01

    failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE...processed AZ31 magnesium plates have been developed. Using a temperature of 300 °C and a 10% reduction per rolling pass, the initially 9-mm-thick plates were... measured ductility along the longitudinal and transverse directions, respectively, than does texture C. 15. SUBJECT TERMS magnesium, AZ31, ECAE

  2. Semi-solid slurry of AZ91 magnesium alloy prepared by electromagnetic stirring near liquidus temperature

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An electromagnetic stirring process near liquidus temperature was designed and demonstrated experimentally to produce semi-solid slurry of AZ91 magnesium alloy, in order to avoid not only contamination from mechanical stirring but also the inflammation of Mg alloy melt at elevated temperature. AZ91 alloy feedstock was isothermally heat treated at 600-610 ℃ for 20 min, and then stirred by electromagnetic field. Globular primary particle characteristic was observed optically in the castings. Mechanical properties were also studied.

  3. A study of weldability and fracture modes in electron beam weldments of AZ series magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chi, C.-T. [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China) and System Manufacturing Center, Chung-Shan Institute of Science and Technology, PO Box 90008-14, Sanxia 237, Taipei, Taiwan (China)]. E-mail: joseph.mse92g@nctu.edu.tw; Chao, C.-G. [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China)]. E-mail: c_g_chao@hotmail.com; Liu, T.-F. [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China)]. E-mail: coe@cc.nctu.edu.tw; Wang, C.-C. [Graduate School of Industrial Design and Architecture, Shih-Chien University, Taipei 104, Taiwan (China)]. E-mail: zcwang@mail.usc.edu.tw

    2006-11-05

    Given the growing need for environmental protection and lightweight construction, electron beam welding (EBW) is becoming the most important welding technology because it can compensate for the poor formability of magnesium alloys. This paper examines interactions between the properties of three AZ series magnesium alloys and welding conditions. The EBW process can yield four kinds of defect in a weld: cavities, the heat-affected zone (HAZ), undercuts, and root concavities. These defects obviously induce stress concentrations in the weld, and may seriously damage its strength. Additionally, the distribution of precipitates ({gamma} phase, Mg{sub 17}Al{sub 12}) in the fusion zone (FZ) changes from a relatively small number of scattered particles to a dense population of dendrites as the Al content of the magnesium alloy increases. Under excessive tensile stress, alloy weldments break in one of two fracture modes: an irregular FZ fracture, or a regular HAZ fracture. AZ31B usually exhibits the former mode and AZ91D the latter, while AZ61A exhibits each mode half the time. The overall weldability, which depends on the random distribution of these precipitates and defects, is found to be greatest for the AZ61A alloy. The best process window, on the other hand, is found for the AZ91D alloy. Finally, we obtain optimum parameters for the EBW process and empirical formulae for the weldment strength as a function of these parameters. These results are closely related to each other.

  4. Effects of grain refinement on mechanical properties and microstructures of AZ31 alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Cerium was added in AZ31 alloy with the contents of 0.4%, 0.8% and 1.2% respectively to produce experimental alloys.The grain refinement of Ce in the as-east and rolled AZ31 alloy were studied by using Polyvar-MET optical microscope with a VSM2000 quantitative analysis system, KYKY2000 SEM and Tecnai G2 20 TEM. And the mechanical properties of AZ31+Ce alloy were tested on a CSS-44100 testing system with computerized data acquisition. The results show that the cerium has a good grain refinement effect on the as-cast AZ31 alloy because cerium can build up a solute enriched zone rapidly during the solidification process. The dynamic recrystallization (DRX) grains less than 10 μm can be obtained in hot rolled AZ31+Ce alloy. A cold rolling deformation degree over than 20% and a following annealing at 400 ℃ for 1h will lead to refine and uniform grains with the sizes of about 25μm. The cerium can form dispersed and thermally stable Al4Ce phase that can prohibit the coarsening of grains in AZ31 +Ce alloy during the hot rolling and annealing process.

  5. Effect of Ca and Y additions on oxidation behavior of AZ91 alloy at elevated temperatures

    Institute of Scientific and Technical Information of China (English)

    CHENG Su-ling; YANG Gen-cang; FAN Jian-feng; LI You-jie; ZHOU Yao-he

    2009-01-01

    In order to develop the ignition-proof magnesium alloy, the effect of alloying elements, Ca and Y, on the oxidation behavior of AZ91 magnesium alloy at elevated temperatures was investigated. The ignition-proof performance, oxide products and oxidation kinetics of Ca- and Y-containing AZ91 alloys were studied. The results indicate that the proper addition of Ca can increase the ignition point of AZ91 alloy greatly. However, the oxide film of Ca-bearing AZ91 alloy formed at elevated temperature is thick and brittle, which is prone to crack in melting and cooling process. In addition, the oxide film of AZ91-xCa alloy is incompact and cannot inhibit the diffusion of reaction particles. The oxide film of AZ91-xCa alloy turns to thin and plastic one after Y is added, and the density of the oxide film increases greatly due to the formation of composite oxide film composed of MgO, CaO and Y2O3.

  6. 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.

  7. BaMa / Raivo Juurak

    Index Scriptorium Estoniae

    Juurak, Raivo, 1949-

    2002-01-01

    Eesti ülikoolide üleminekust 3+2 süsteemile. Lühend BaMa on tulnud kasutusele seoses Euroopa ülikoolide õppekavade reformimisega ning tähistab õppekava, kus esimese astme läbimise järel omandatakse bakalaureuse- ja teise järel magistrikraad. Õppekavade tüüpidest Eesti ja Euroopa Liidu kõrgkoolides ning Bologna deklaratsioonist

  8. Y-Ba Superconducting Ceramics

    Science.gov (United States)

    Shunbao, Tian; Xiaofei, Li; Tinglian, Wen; Zuxiang, Lin; Shichun, Li; Huijun, Yu

    Polycrystalline Y-Ba-Cu-O superconducting materials have been studied. It was found that chemical composition and processing condition may play an important role in the final structure and superconducting properties. The density has been determined and compared with the calculated value according to the structure model reported by Bell Labs. The grain size and the morphology of the materials were observed by SEM.

  9. 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.

  10. 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.

  11. Microstructural development of high temperature deformed AZ31 magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shahbeigi Roodposhti, Peiman, E-mail: pshahbe@ncsu.edu; Sarkar, Apu; Murty, Korukonda Linga

    2015-02-25

    Due to their significant role in automobile industries, high temperature deformation of Mg–Al–Zn alloys (AZ31) at constant stress (i.e. creep) were studied at a wide range of stresses and temperatures to characterize underlying deformation mechanism, dynamic recrystallization (DRX) and dislocation density evolution. Various microstructures (e.g. grain growth & DRX) are noted during steady-state creep mechanisms such as grain boundary sliding (GBS), dislocation glide creep (DGC) and dislocation climb creep (DCC). Although a combination of DRX and grain growth is characteristic of low stacking fault energy materials like Mg alloys at elevated temperatures, observation reveals grain growth at low strain-rates (GBS region) along with dynamic recovery (DRV) mechanism. X-Ray Diffraction (XRD) analysis revealed a decrease in dislocation density during GBS region while it increased under dislocation based creep mechanisms which could be related to the possible DRV and DRX respectively. Scanning Electron Microscopic (SEM) characterization of the fracture surface reveals more inter-granular fracture for large grains (i.e. GBS region with DRV process) and more dimple shape fracture for small grains (i.e. DGC & DCC region with DRX)

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

    Science.gov (United States)

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

    2016-09-01

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

  13. Direct Electroless Nickel Plating on AZ91D Magnesium Alloy from a Sulfate Solution and its Deposition Mechanism

    Institute of Scientific and Technical Information of China (English)

    GU Chang-dong; LIAN Jian-she; LI Guang-yu; NIU Li-yuan; JIANG Zhong-hao

    2004-01-01

    A bath of electroless plating Ni on the AZ91D magnesium alloy, containing sulfate nickel, was given in this paper. The nucleation mechanism of Ni-P deposits on the AZ91D magnesium alloy was studied by using XRD and SEM.The electroless Ni-P deposits were preferentially nucleated on the β (Mg17Al12) phase and extended to the primary and eutectic α phases of the AZ91D magnesium alloy.

  14. Direct Electroless Nickel Plating on AZ91D Magnesium Alloy from a Sulfate Solution and its Deposition Mechanism

    Institute of Scientific and Technical Information of China (English)

    GUChang-dong; LIANJian-she; LIGuang-yu; NIULi-yuan; JIANGZhong-hao

    2004-01-01

    A bath of electroless plating Ni on the AZ91D magnesium alloy, containing sulfate nickel, was given in this paper. The nucleation mechanism of Ni-P deposits on the AZ91D magnesium alloy was studied by using XRD and SEM. The electroless Ni-P deposits were preferentially nucleated on the β(Mg17Al12) phase and extended to the primary and eutectic α phases of the AZ91D magnesium alloy.

  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. 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.

  17. 76 FR 62760 - Foreign-Trade Zone 277-Western Maricopa County, AZ; Application for Temporary/Interim...

    Science.gov (United States)

    2011-10-11

    .../Interim Manufacturing Authority; Sub-Zero, Inc.; (Refrigerators); Goodyear, AZ An application has been... County Foreign Trade Zone, Inc., grantee of FTZ 277, requesting temporary/ interim manufacturing...

  18. 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.

  19. IBFM for Ba isotopes and chaoticity

    Energy Technology Data Exchange (ETDEWEB)

    Bucurescu, D.; Cata-Danil, G.; Ivascu, M.; Ur, C.A. (Inst. of Atomic Physics, Bucharest (Romania)); Gizon, A.; Gizon, J. (Inst. des Sciences Nucleaires, 38 - Grenoble (France))

    1992-08-01

    Fluctuation properties have been analysed for the energy levels predicted by IBFM calculations in the Ba isotopes {sup 121}Ba to {sup 131}Ba. The results indicate, in general, a situation which is close to the chaotic limit. For the lighter isotopes studied (121 and 123), a phase transition is obtained in the low-spin, positive parity states, from a situation close to regularity at low excitation energies, towards chaoticity at higher excitations. (orig.).

  20. AMiBA, XMM, and Cluster Surveys

    CERN Document Server

    Liang, H

    2001-01-01

    The Array for Microwave Background Anisotropy (AMiBA) is an interferometric array of 19 dishes co-mounted on a steerable platform and operating at 95GHz. One of the main scientific aims of AMiBA is to conduct cluster surveys using the Sunyaev-Zel'dovich (SZ) effect. Here we explore the potential of AMiBA as a tailor-made SZ instrument for the study of cluster physics and cosmology via cluster surveys out to the epoch of cluster formation. In particular, we explore the potential of combining AMiBA cluster surveys with the XMM-LSS (Large Scale Structure) survey.

  1. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    TEMPLETON, A.M.

    1999-07-08

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

  3. Effect of thermal processing on microstructure and mechanical properties of AZ80 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The influences of deformation temperature and deformation degree on the mierostructure and mechanical properties of AZ80 magnesium alloy were investigated by the adoption of isothermal plain strain compression experiment. The results show that thermal compression processing can refine the grain size and the tensile strength of all the deformed AZ80 magnesium alloys is increased to the maximum of 320 MPa. With the increasing of deformation temperature, the tensile strength decreases; with the increasing of the deformation degree, the tensile strength increases significantly in the temperature range of 200-300 ℃ and becomes stable at temperature higher than 300 ℃. During the compression processing of AZ80 magnesium alloys, at lower temperature(300 ℃), dynamic reerystallization is complete and refined grainstrengthening is dominant, leading to little effect of deformation degree on mechanical properties.

  4. Microstructure and corrosion property of AZ61 magnesium alloy by electromagnetic stirring

    Institute of Scientific and Technical Information of China (English)

    FANG Can-feng; ZHANG Xing-guo; JI Shou-hua; JIN Jun-ze; CHANG Yu-bao

    2005-01-01

    The influence of permanent-magnet-driven stirring during solidification on the microstructure and corrosion property of AZ61 magnesium alloy was investigated. The corrosion behaviour of AZ61 was studied in 3.5mol/L NaCl by measuring electrochemical polarization. The results show that the permanent-magnet stirring refines the microstructure of AZ61 magnesium alloy, which improves the precipitation amount and distribution uniformity of β phase and decreases the content of hydrogen, but it has less influence on the distribution uniformity of Zn. The change of precipitation amount of β phase influences the corrosive nature of the matrix, and it has no direct proportion with the corrosion resistance of the matrix.

  5. Improvement on the Corrosion Resistance of AZ91D Magnesium Alloy by Aluminum Diffusion Coating

    Institute of Scientific and Technical Information of China (English)

    Hongwei HUO; Ying LI; Fuhui WANG

    2007-01-01

    By combination of magnetron sputtering deposition and vacuum annealing, an aluminum diffusion coating was prepared on the substrate of AZ91D alloy to improve its corrosion resistance. The microstructure and composition of the diffusion coating was investigated by scanning electron microscopy and X-ray diffraction. The diffusion coating was mainly comprised of β phase-Al12Mg17. The continuous immersion test in 3.5 wt pct neutral NaCl solution indicated that the specimen with diffusion coating had better corrosion resistance compared with the bare AZ91D alloy specimen. The potentiodynamic polarization measurement indicated that the diffusion coating could function as an effectively protective layer to reduce the corrosion rate of AZ91D alloy when exposed to 3.5 wt pct NaCl solution.

  6. Interfacial reaction in squeeze cast SiCw/AZ91 composites with different binders

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The whisker/matrix interfaces in squeeze cast SiCw/AZ91 composites with different binders (silica binder, acid aluminum phosphate binder and without binder), were studied by transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). The SiCw/AZ91 interface is very clean in the composites with no binders. For the composites with acid aluminum phosphate binders or silica binders, there exists fine discrete interfacial reaction products MgO at the interface, and a definite orientation relationship between MgO and SiCw. The interfacial reaction products MgO is unevenly distributed at different parts of the composite ingot with silica binder, and mainly distributed to the interface at the side part of the composite cylinder. While in the SiCw/AZ91 composite with acid aluminum phosphate binder, MgO particles are distributed evenly at the interface in almost all the parts of the composite ingot.

  7. 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.

  8. Analysis of laser welded joint of microstructure and mechanical properties of dissimilar magnesium AZ31B and AZ91D%AZ31B/AZ91D 异种镁合金激光焊接头组织性能分析

    Institute of Scientific and Technical Information of China (English)

    刘军; 黄飞; 稼海星; 侯继军; 杜赵新

    2015-01-01

    Studies on the microstructure and properties of dissimilar magnesium AZ31B and AZ91D joints welded by CO2 laser using optical microscope,tensile test,microhardness test and etc are presented.The results show that a sound weld can be ob-tained with a laser power of 1 800 W,a welding speed of 600 mm/min and a flow rate of shielding gas of 15 L/min.Analysis of microstructure of welded joint shows that the heat affected zone is not apparent,the growth of the grains in base metal close to the fusion line are not obvious,and the grain size in weld is refined.X-ray diffraction shows that there areα-Mg andβ-Al12 Mg17 phases in the welded zone.EDS analysis shows that the element’s content of Mg,Al in the welded zone are between that of the base metal AZ91D and AZ31B.Tension results show that the fracture is mainly happened on AZ91D,which indicates that the tensile strength of joint is higher than the base metal AZ91D,and the dominant fracture mechanism is brittle fracture.The hard-ness of welded zone is higher than two base metals.%针对 AZ31B 和 AZ91D 异种镁合金材料的激光焊接问题,通过光学显微镜、拉伸试验、显微硬度测试等手段分析研究AZ31B 和 AZ91D 异种镁合金 CO2激光焊接头组织性能。结果表明:在功率为1800 W,焊接速度为600 mm/min,保护气流量为15 L/min 时,可以获得成形良好的焊缝。对焊接接头微观组织进行分析发现,接头热影响区不明显,熔合线附近母材侧晶粒未发生明显长大,焊缝晶粒明显细化;通过 XRD 检测可知焊缝区主要由α-Mg 和β-Al12 Mg17这2相组成;通过 EDS 能谱分析得到焊缝区 Mg、Al 元素的质量分数介于2种母材之间;通过拉伸试验发现,断裂位置位于 AZ91D 母材上,焊接接头抗拉强度高于AZ91D 母材,扫描断口显示断裂方式为脆性断裂;焊缝硬度高于2种母材硬度。

  9. Effects of Ce on damping capacity of AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    黄正华; 郭学锋; 张忠明

    2004-01-01

    The microstructures and damping capacity of AZ91D cast alloys containing various Ce contents were investigated. Damping capacity (Q-1) of the alloys was measured by cantilever beam technique, and the relationship between damping capacity and strain amplitude was investigated. The results show that Al4 Ce phase is formed in AZ91D alloy after adding a certain quantity of Ce contents, then as-cast microstructures of the alloys are refined.Meanwhile the damping capacity of the alloys is also improved. When the mass fraction of Ce is 0.7 %, the most obvious refinement effect and the maximum damping capacity can be obtained. When the damping capacity (Q-1) is 2. 728 × 10-3 , 61% increment can be obtained compared with unmodified AZ91D alloy. The damping capacity of the alloys is relative to strain amplitude, and the damping behavior can be explained by the theory of Granato and Lucke.

  10. Structural characterization and property of in-situ synthesized AZ91-Mg2Si composite

    Institute of Scientific and Technical Information of China (English)

    DONG Long-xiang; WU Yao-ming; DOU Chuan-guo; XU Guo-gen; WANG Li-min

    2006-01-01

    A new-type Mg2Si composite was prepared with Mg-9Al-1Zn (AZ91) alloy and vermiculite as raw materials by melt infiltration method. The results show that the microstructure of composite consists of a large amount of Mg2Si precipitates and a little amount of MgO embedded in α-Mg matrix. The Vickers hardness of the composite is obviously higher than that of matrix of AZ91 alloy. Moreover, the composite exhibits excellent compressive property. The ultimate compressive strength of the material is 290 MPa, the yield strength is 175 MPa, and the elongation is about 5%, which are higher than those of AZ91alloy.

  11. Grain refinement of AZ31 magnesium alloy by Al-Ti-C-Y master alloy

    Institute of Scientific and Technical Information of China (English)

    XU Chunxiang; LU Binfeng; L(U) Zhengling; LIANG Wei

    2008-01-01

    Al-Ti-C-Y master alloy was prepared by combining SHS technique and melting-casting method. The microstructure of master alloy and its grain-refining effect on AZ31 alloy were investigated by means of OM, XRD, SEM and EDS. Experimental results indicated that the prepared master alloy consisted of α-Al, TiAl3, TiC and Al3Y phases, and exhibited good grain-refining performance of AZ31 alloy. Morphology of α-Mg changed from coarse dendritic to fine equiaxed and the average grain size of α-Mg matrix reduced from the original 580 to 170 μm after adding 1.0 wt.% master alloy. The grain refining efficiency of Al-Ti-C-Y master alloy on AZ31 alloy was mainly attributed to heterogeneous nucleation of TiC particles and grain growth restriction of Al-Y compound or TiC at grain boundaries.

  12. In vitro Study on Biodegradable AZ31 Magnesium Alloy Fibers Reinforced PLGA Composite

    Institute of Scientific and Technical Information of China (English)

    Y.H.Wu; N.Li; Y.Cheng; Y.F.Zheng; Y.Han

    2013-01-01

    AZ31 magnesium alloy fibers reinforced poly(lactic-co-glycolic acid) (PLGA) composites were prepared and their mechanical property,immersion corrosion behavior and biocompatibility were studied.The tensile test showed that with the addition of AZ31 fibers,the composites had a significant increment in tensile strength and elongation.For the direct cell attachment test,all the cells showed a healthy morphology and spread well on the experimental sample surfaces.The immersion results indicated that pH values of the immersion medium increased with increasing AZ31 fiber contents.All the in vitro experimental results indicated that this new kind of magnesium alloy fibers reinforced PLGA composites show a potential for future biomedical applications.

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

    Science.gov (United States)

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

    2011-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    TEMPLETON, A.M.

    2000-04-10

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

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

    Energy Technology Data Exchange (ETDEWEB)

    TEMPLETON, A.M.

    2000-03-06

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

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

    Energy Technology Data Exchange (ETDEWEB)

    TEMPLETON, A.M.

    2000-01-31

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

  17. Influence of Procedure Parameters on Rheological Property of Semi-Solid AZ91D Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    Jiang Yunxi; Xie Shuisheng; Li Xinggang; Li Lei

    2004-01-01

    Semi-solid AZ91D magnesium alloy was investigated in isothermal steady-state condition. The influence of stirring technological parameters such as stirring temperature and shear rate to apparent viscosity of semi-solid alloy slurry was discussed. Apparent viscosity increases with stirring temperature decreases at the same shear rate. At the same stirring temperature, apparent viscosity decreases rapidly at first with shear rate increases, and then apparent viscosity decreases slowly with shear rate increases, when shear rate reaches a certain value, apparent viscosity appears tiny increase. According to the experimental data, the relation between solid volume fraction and apparent viscosity of semi-solid AZ9l D alloy at shear rate 238 s- 1 is fitted by regression method, it supplies useful data to the numerical simulation of semi-solid AZ91D alloy die casting process.

  18. 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

  19. Patrón de consumo e ingestas recomendadas de azúcar

    Directory of Open Access Journals (Sweden)

    Joan Quiles i Izquierdo

    2013-07-01

    Full Text Available 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 estimó que un 20% de la ingesta calórica de los españoles procede de los hidratos de carbono denominados azúcares. Se ha asociado el consumo de azúcar con diversas patologías (diabetes, obesidad, caries, cardiovasculares si bien estas relaciones no presentan consistencia en las evidencias encontradas. La información alimentaria a través del etiquetado nutricional, incluida la relativa a los azúcares presentes en los alimentos, facilitada al consumidor persigue proteger la salud de los mismos y garantizar su derecho a la información para que puedan tomar decisiones con criterio. A la vista de las distintas valoraciones y estudios existentes y sobre todo, en ausencia de una evidencia científica sólida que arroje datos concretos sobre los que realizar recomendaciones, el mejor consejo nutricional para la población general podría ser llevar una dieta variada y equilibrada con alimentos y nutrientes procedentes de diversas fuentes, combinando dicha dieta con el ejercicio y la actividad física. De manera más concreta, un consumo moderado de azúcar (< 10% de la energía total en el anterior contexto de dieta variada y equilibrada, es compatible.

  20. 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

  1. Microstructure and corrosion behavior of electrodeposited nano-crystalline nickel coating on AZ91 Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zarebidaki, Arman, E-mail: arman.zare@iauyazd.ac.ir; Mahmoudikohani, Hassan, E-mail: hassanmahmoudi.k@gmail.com; Aboutalebi, Mohammad-Reza

    2014-12-05

    Highlights: • Activation, zincating, and Cu electrodeposition were used as pretreatment processes for electrodeposition of nickel coatings. • Nano-crystalline nickel coatings were successfully electrodeposited onto the AZ91 Mg alloys. • Effect of nickel electrodeposited coating on the corrosion resistance of AZ91 Mg alloy has been studied. - Abstract: In order to enhance the corrosion resistance, nickel coating was electrodeposited onto AZ91 Mg alloy. Activation, zincating, and Cu electrodeposition used as pretreatment processes for better adhesion and corrosion performance of the nickel over layer. The corrosion properties of the AZ91 Mg alloy, nickel electroplated AZ91 Mg alloy, and pure nickel was assessed via polarization and electrochemical impedance spectroscopy (EIS) methods in 3.5 wt% NaCl solution. Moreover, the structure of the coating was investigated by means of X-ray diffraction, whereas specimen’s morphology and elemental composition were analyzed using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). Measurements revealed that the coating has a nano-crystalline structure with the grain size of 95 nm. Corrosion results showed superior corrosion resistance for the coated AZ91 Mg alloy as the corrosion current density decreased from 2.5 × 10{sup −4} A cm{sup −2}, for the uncoated sample, to 1.5 × 10{sup −5} A cm{sup −2}, for coated specimen and the corrosion potential increased from −1.55 V to −0.98 V (vs. Ag/AgCl) at the same condition.

  2. Effect of filler wire on the joint properties of AZ31 magnesium alloys using CO2 laser welding

    Institute of Scientific and Technical Information of China (English)

    Wang Hongying; Li Zhijun

    2007-01-01

    Laser welding with filler wire of AZ31 magnesium alloys is investigated using a CO2 laser experimental system. The effect of three different filler wires on the joint properties is researched. The results show that the weld appearance can be effectively improved when using laser welding with filler wire. The microhardness and tensile strength of joints are almost the same as those of the base metal when ER AZ31 or ER AZ61 wire is adopted. However, when the filler wire of ER 5356 aluminum alloy is used, the mechanical properties of joints become worse. For ER AZ31 and ER AZ61 filler wires, the microstructure of weld zone shows small dendrite grains. In comparison, for ER 5356 filler wire, the weld shows a structure of snowy dendrites and many intermetallic compounds and eutectic phases distribute in the dendrites. These intermetallic constituents with low melting point increase the tendency of hot crack and result in fragile joint properties. Therefore, ER AZ31 and ER AZ61 wire are more suitable filler material than ER 5356 for CO2 laser welding of AZ31 magnesium alloys.

  3. 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

  4. Incremental forming of free surface with magnesium alloy AZ31 sheet at warm temperatures

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The formability of AZ31 sheet begins to increase drastically at 150 ℃. The incremental forming technique was thus applied to AZ31 sheet at 150 ℃ to utilize the formability to its fullest capacity at the lowest possible temperature for forming applications. A surface scanning technique was used followed by the tool path generation to incrementally form an egg surface. After thorough examination of various tool paths, the surface was most successfully produced by forming an intermediate shape followed by a series of tool paths. Flexible scale stickers were devised to improve the accuracy in the measurement of grid deformation.

  5. Qualitative Research of AZ31 Magnesium Alloy Aircraft Brackets Produced by a New Forging Method

    Directory of Open Access Journals (Sweden)

    Dziubińska A.

    2016-06-01

    Full Text Available The paper reports a selection of numerical and experimental results of a new closed-die forging method for producing AZ31 magnesium alloy aircraft brackets with one rib. The numerical modelling of the new forming process was performed by the finite element method.The distributions of stresses, strains, temperature and forces were examined. The numerical results confirmed that the forgings produced by the new forming method are correct. For this reason, the new forming process was verified experimentally. The experimental results showed good agreement with the numerical results. The produced forgings of AZ31 magnesium alloy aircraft brackets with one rib were then subjected to qualitative tests.

  6. Phosphating process of AZ31 magnesium alloy and corrosion resistance of coatings

    Institute of Scientific and Technical Information of China (English)

    CHENG Ying-liang; WU Hai-lan; CHEN Zhen-hua; WANG Hui-min; LI Ling-ling

    2006-01-01

    Zinc phosphate films were formed on AZ31 magnesium alloy by immersing into a phosphatation bath to enhance the corrosion resistance of AZ31. Different films were prepared by changing the processing parameters such as immersing time and temperature. The corrosion protection of the coatings was studied by electrochemical measurements such as electrochemical impedance spectroscopy, potentiodynamic polarization curves, and the structure of the films were studied by metalloscopy and X-ray diffraction (XRD). The results show that, the film formed at 80 ℃, 10 min has the highest corrosion resistance. The XRD patterns show that the film consists of hopeite (Zn3(PO4)2·xH2O).

  7. Numerical simulation of microstructure formation of AZ91 using mCA method

    Institute of Scientific and Technical Information of China (English)

    HE Bo-lin; LI Qiu-ping; QI Qing-yan; YAO Xiang-dong

    2006-01-01

    A stochastic model for simulating the microstructure formation of Mg alloy AZ91 during solidification was developed based on the finite element method(FEM) for macroscopic model of heat transfer calculation and a modified Cellular Automaton (mCA) for microscopic modeling of nucleation, growth of crystal. In this model, the effect of solute redistribution, interface curvature and preferred orientation was considered. A numerical simulation was developed with C++ program language. The computation was carried out to understand the effect of varying processing parameters, such as nucleation parameters and heat transfer coefficient, on the microstructure formation of AZ91. The result of simulation was displayed on screen.

  8. 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

    mu m of the contaminated surface was required to reach corrosion rates less than 1 mm/year in salt spray condition. Among the three organic acids examined, acetic acid is the best choice. Oxalic acid can be an alternative while citric acid is not suitable for cleaning AZ31 sheet, because......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...

  9. Effect of side transmission of power ultrasonic on structure of AZ81 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    张海波; 翟启杰; 戚飞鹏; 龚永勇

    2004-01-01

    In order to promote the application of power ultrasonic in metallurgic industry, ultrasonic vibration is introduced from the side of AZ81 ingot by adopting the automatic-attracting amplitude transformer horn which has independently been designed and produced, and the effect of the side transmission of ultrasonic on the solidification structure of metal is investigated. The results show that under this experimental condition, power ultrasonic can greatly improve the solidification structure of AZ81 magnesium alloy. Compared with the traditional modification methods in which inoculants are added into melt, power ultrasonic has a better performance. The present research gives us a new way for the application of ultrasonic refinement technique.

  10. Grain refinement of AZ31 magnesium alloy by electromagnetic stirring under effect of grain-refiner

    Indian Academy of Sciences (India)

    S Y Gao; Q C Le; Z Q Zhang; J Z Cui

    2012-08-01

    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 grain refiner. Electromagnetic stirring can `activate’ the Al4C3 particles, resulting in more heterogeneous nucleation sites for the primary -Mg grains. But, longer holding time can `deactivate’ the Al4C3 particles and poison the grain refining effect.

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

    Science.gov (United States)

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

    2016-02-01

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

  12. AZ31镁合金热变形过程中的流变应力%The Flow Stress During Hot Deformation of AZ31 Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    王庆; 林金保; 黄庆学; 王翀

    2014-01-01

    在Gleeble-1500热模拟试验机和UTM5305实验机上以不同的变形条件对AZ31镁合金进行高温热变形试验,研究该材料在高温热变形过程中的真应力应变。研究结果证明:在变形过程中的AZ31镁合金的真应力随应变速率增大、变形温度降低而升高。在压缩变形过程中的真应力峰值、真应变和动态再结晶与拉伸变形过程相比有明显差异;该镁合金热变形过程中的真应力为用包含Arrhenius项的Zener-Hollomon参数来描述,其压缩拉伸变形激活能分别为132.38 kJ/mol和Q=255.26 kJ/mol.%The behaviors of flow stress of alloy AZ31 Magnesium Alloy during high-temperature deformation were studied by isothermal deformation test on Gleeble-1500 and UTM5305 thermal mechanical simulator. The results show that the true stress increases with the strain rate and decreases with temperature. Compared with the tensile deformation process,the peak of true stress,true strain and dynamic recrystallization of compression process has a significant difference. The flow stress of AZ31 Magnesium Alloy during hot deformation can be described by using Zener-Hollomon parameter including Arrhenius item,and the compression deformation activation energy is 132. 38 kJ/mol,the tensile deformation activation energy is 255. 26 kJ/mol.

  13. 纳米晶AZ31镁合金粉末制备的研究%Preparation of Nanocrystalline AZ31 Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    郭宇; 刘广东

    2010-01-01

    研究了AZ31镁合金粉末在氢化一脱氢过程中的组织结构与粉末形貌演变规律,在350℃的条件下进行真空脱氢处理,MgH2转变为Mg,获得晶粒尺寸约为40nm的纳米晶镁合金粉末.

  14. 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.

  15. Yoğun bakım hastalarında plevral ve parankimal akciğer patolojilerini tanımlamada yatak başı yapılan akciğer ultrasonografisinin yeri

    OpenAIRE

    Yilmaz, Özgür

    2011-01-01

    GİRİŞ: Günümüz yoğun bakım pratiğinde hızlı ve doğru teşhis koymak amacı ile daha az mobilizasyon gerektiren, hasta için non-invaziv ve yan etkisi az olan tekniklerin tercih edilmesi eğilimi, yatak başı ultrasonografiye olan ilginin giderek artmasına neden olmuştur.Biz bu çalışma ile pnömoni ve/veya plevral effüzyon şüphesi olan kritik has...

  16. AZ91D镁合金板材电脉冲轧制工艺研究%Research on electrostimulated rolling of AZ91D magnesium alloy plate

    Institute of Scientific and Technical Information of China (English)

    阎峰云; 黄旺; 杨群英; 程从德

    2010-01-01

    利用自主研发的电脉冲轧制设备,对AZ91D镁合金板材进行了电脉冲轧制实验,证明了AZ91D镁合金具有一定的可轧性,并获得了合适的工艺参数.对高能电脉冲和轧制力共同作用下AZ91板材变形量、力学性能及微观组织的变化机理进行了分析,并与常规轧制进行了比较.结果表明,由于电塑性效应的影响,与常规轧制相比,道次累计变形量达到了40%,显微组织变化明显,晶粒明显细化,晶粒和晶界明显拉长,抗拉强度等力学性能有显著提高.

  17. 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...

  18. 241-AZ-101 Waste Tank Color Video Camera System Shop Acceptance Test Report

    Energy Technology Data Exchange (ETDEWEB)

    WERRY, S.M.

    2000-03-23

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

  19. A generalized AZ-non-Maxwellian velocity distribution function for space plasmas

    Science.gov (United States)

    Abid, A. A.; Khan, M. Z.; Lu, Quanming; Yap, S. L.

    2017-03-01

    A more generalized form of the non-Maxwellian distribution function, i.e., the AZ-distribution function is presented. Its fundamental properties are numerically observed by the variation of three parameters: α (rate of energetic particles on the shoulder), r (energetic particles on a broad shoulder), and q (superthermality on the tail of the velocity distribution curve of the plasma species). It has been observed that (i) the A Z - distribution function reduces to the ( r , q ) - distribution for α → 0 ; (ii) the A Z - distribution function reduces to the q - distribution for α → 0 , and r → 0 ; (iii) the A Z -distribution reduces to Cairns-distribution function for r → 0 , and q → ∞ ; (iv) the AZ-distribution reduces to Vasyliunas Cairns distribution for r → 0 , and q = κ + 1 ; (v) the AZ-distribution reduces to kappa distribution for α → 0 , r → 0 , and q = κ + 1 ; and (vi) finally, the AZ-distribution reduces to Maxwellian distribution for α → 0 , r → 0 , and q → ∞ . The uses of this more generalized A Z - distribution function in various space plasmas are briefly discussed.

  20. 78 FR 3027 - Notice of Temporary Closures of Public Lands in La Paz County, AZ

    Science.gov (United States)

    2013-01-15

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

    1. 76 FR 5398 - Notice of Temporary Closure of Selected Public Lands in La Paz County, AZ

      Science.gov (United States)

      2011-01-31

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

    2. INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

      Institute of Scientific and Technical Information of China (English)

      2007-01-01

      The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.

    3. Microstructure refinement of AZ91D alloy solidified with pulsed magnetic field

      Institute of Scientific and Technical Information of China (English)

      WANG Bin; YANG Yuan-sheng; ZHOU Ji-xue; TONG Wen-hui

      2008-01-01

      The effects of pulsed magnetic field on the solidified microstructure of an AZ91D magnesium alloy were investigated. The experimental results show that the remarkable microstructural refinement is achieved when the pulsed magnetic field is applied in the solidification of AZ91D alloy. The average grain size of the as-cast microstructure of AZ91D alloy is refined to 104μm. Besides the grain refinement, the morphology of the primary α-Mg is changed from dendritic to rosette, then to globular shape with changing the parameters of the pulsed magnetic field. The pulsed magnetic field causes melt convection during solidification, which makes the temperature of the whole melt homogenized, and produces an undercooling zone in front of the liquid/solid interface by the magnetic pressure, which makes the nucleation rate increased and big dendrites prohibited. In addition, primary α-Mg dendrites break into fine crystals, resulting in a refined solidification structure of the AZ91D alloy. The Joule heat effect induced in the melt also strengthens the grain refinement effect and spheroidization of dendrite arms.

    4. 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.

    5. Effect of cooling rate on microstructure and compressive performance of AZ91 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      YANG Lin; FENG Hui; QIU Ke-qiang; CHEN Li-jia; LIU Zheng

      2006-01-01

      Effect of cooling rate on both microstructure and room temperature compressive performance of the AZ91 magnesium alloy was investigated. The experimental results show that with increasing cooling rate, the quantity of the solid solution phase increases and the fraction of secondary phase Mg17Al12 decreases. The almost single solid solution phase can be obtained with using liquid nitrogen as a coolant. The compressive strengths of the rapid solidified AZ91 magnesium alloys are higher than those of normal cast alloy, and decrease with increasing cooling rate. After artificial aging treatment for 14 h at 168 ℃, the compressive strength of the rapidly solidified AZ91 magnesium alloy cooled in liquid nitrogen increases from 253.5 to 335.3 MPa, while the compressive yield strength increases from 138.1 to 225.91 MPa. The improvement in the compressive strength of the rapidly solidified AZ91magnesium alloys can be attributed to the hardening effect from fine secondary phase.

    6. 78 FR 40503 - Notice of Realty Action: Direct Sale of Public Lands in Pima County, AZ

      Science.gov (United States)

      2013-07-05

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

    7. 78 FR 71641 - Notice of Realty Action: Direct Sale of Public Land in Graham County, AZ

      Science.gov (United States)

      2013-11-29

      ... Bureau of Land Management Notice of Realty Action: Direct Sale of Public Land in Graham County, AZ AGENCY... Management (BLM), Safford Field Office (SFO), is considering a noncompetitive direct sale of approximately 15...: Written comments concerning the proposed direct sale should be sent to Scott Cooke, Field Manager,...

    8. 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 Chandler Municipal Airport under the provisions of 49 U.S.C. 47501 et seq. (Aviation Safety and...

    9. THE APPARENT VISCOSITY OF SEMI-SOLID AZ91D ALLOY AT STEADY STATE

      Institute of Scientific and Technical Information of China (English)

      Z.S. Zhen; W.M. Mao; S.J. Yan; A.M. Zhao; C.L. CuI; X.Y. Zhong

      2002-01-01

      The Rheological behavior of semi-solid AZ91D at steady state is studied using a Couettetype viscometer in the present paper. The results show that the apparent viscosity ofsemi-solid AZ91D at the steady state increases with the solid fraction increasing, andgoes up sharply when the solid fraction reaches a certain value, which is called criticalfraction. In addition, the apparent viscosity of semi-solid AZ91D at the steady statetakes on a distinct downtrend with the shearing rate increasing, which indicates astrong shear thinning property. In addition, the critical solid fraction becomes higherunder larger shearing rate, owing to the more globular shape of the solid particles.Based on the present experiment results, an empirical equation is built as that, relatingthe steady state apparent viscosity of semi-solid AZ91D with the solid fraction fs andshearing rate γ at the same time: ηapp=10. 74exp(6.95fs)γ-0.86.

    10. 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.

    11. 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...

    12. Effect of Neodymium on As-Cast Microstructure and Mechanical Properties of AZ31 Wrought Alloy

      Institute of Scientific and Technical Information of China (English)

      Li Mingzhao; Fan Jinping; Zhang Junyuan; Liu Xuguang; Xu Bingshe

      2007-01-01

      Nd in the form of powder or intermediate alloy was added to AZ31 wrought alloy. The as-obtained alloy was characterized and tested with respect to its microstructure and mechanical properties. The relationship between the microstructure, mechanical properties and tensile fracture mechanism were discussed, with relevant alloys as reference for comparison. Experimental results show that the same quantity of Nd was added into AZ31 in powder form or in intermediate alloy, the absorption rate of Nd reached only 10.8% for the former case and as high as 95% for the later case. Pure Nd powder was added, no new compound was detected, but it served as reductant and purified alloy melt, resulting in improving the tensile strength while Nd was added into AZ31 as Mg-Nd intermediate alloy. The compound Al2Nd and Mg12 Nd were formed in magnesium alloy, which were distributed in the matrix in the shapes of strip and particle, evidently refined the as-cast structure. The as-cast tensile strength (228MPa) of adding pure Nd powder approximated to the figure (245MPa) of adding Mg-Nd intermediate alloy. The tensile fracture mchanism of as-cast AZ31 transformed from cleavage fracture into quasi-cleavage fracture.

    13. 76 FR 42155 - Arizona Disaster #AZ-00017 Declaration of Economic Injury

      Science.gov (United States)

      2011-07-18

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

    14. 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...

    15. 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.

    16. 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,...

    17. 76 FR 23787 - Voluntary Termination of Foreign-Trade Subzone 75D, STMicroelectronics, Inc., Phoenix, AZ

      Science.gov (United States)

      2011-04-28

      ...., Phoenix, AZ Pursuant to its authority under the Foreign-Trade Zones Act of June 18, 1934, as amended (19 U... issued a grant of authority to the City of Phoenix (grantee of FTZ 75) authorizing the establishment of Foreign-Trade Subzone 75D at the STMicroelectronics, Inc., facility in Phoenix, Arizona (Board Order...

    18. 75 FR 64708 - Reorganization of Foreign-Trade Zone 75 under Alternative Site Framework; Phoenix, AZ

      Science.gov (United States)

      2010-10-20

      ...; Phoenix, AZ Pursuant to its authority under the Foreign-Trade Zones Act of June 18, 1934, as amended (19 U...; Whereas, the City of Phoenix, grantee of Foreign-Trade Zone 75, submitted an application to the Board (FTZ... Maricopa County and portions of Pinal and Yavapai Counties, Arizona, within and adjacent to the...

    19. 78 FR 17097 - Safety Zone; Lake Havasu Triathlon; Lake Havasu City, AZ

      Science.gov (United States)

      2013-03-20

      ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lake Havasu Triathlon; Lake Havasu City, AZ... Havasu Triathlon. This temporary safety zone is necessary to provide safety for the swimmers, crew... Triathlon will consist of 600 participants. The waterside swim course consists of 1500 meters in Lake...

    20. Quasiparticle Band Structure of BaS

      Institute of Scientific and Technical Information of China (English)

      LU Tie-Yu; CHEN De-Yan; HUANG Mei-Chun

      2006-01-01

      @@ We calculate the band structure of BaS using the local density approximation and the GW approximation (GWA),i.e. in combination of the Green function G and the screened Coulomb interaction W. The Ba 4d states are treated as valence states. We find that BaS is a direct band-gap semiconductor. The result shows that the GWA band gap (Eg-Gw = 3.921 eV) agrees excellently with the experimental result (Eg-EXPT = 3.88 eV or 3.9eV).

    1. 挤压AZ31B镁合金多轴疲劳寿命预测%MULTIAXIAL FATIGUE LIFE PREDICTION FOR EXTRUDED AZ31B MAGNESIUM ALLOY

      Institute of Scientific and Technical Information of China (English)

      熊缨; 程利霞

      2012-01-01

      采用挤压AZ31B镁合金薄壁圆筒试样,分别进行了单轴和多轴加载下的对称应变控制疲劳实验,研究了不同加载路径对疲劳寿命的影响.单轴加载包括对称拉压和扭转路径,多轴加载包括45°比例加载和90°非比例加载路径.结果表明,在加载的等效应变幅值为0.3% 0.55%附近,4种加载路径下的应变-寿命曲线均出现了不连续的拐点;比例加载路径在等效应变幅大于0.45%时疲劳寿命最高,拉压路径在等效应变幅小于0.45%时疲劳寿命最高;非比例加载路径的疲劳寿命最低.使用基于临界平面法的多轴疲劳模型FS,SWT以及修正SWT分别预测了各个路径加载下的疲劳寿命.预测结果表明,SWT模型对于拉压和循环扭转加载下寿命预测结果误差较大;FS模型与修正SWT模型可以较好地预测挤压AZ31B镁合金各个路径加载下的疲劳寿命.%Magnesium alloy components were widely used in automobile and aircraft industries, due to their light weight, high specific strength, stiffness, damping capacity, machinability, and recyclability. Engineering components subjected cyclic loading inevitably and led to fatigue failure. Most studies on magnesium alloy were focus on uniaxial fatigue, very limited work has been done of magnesium alloys under multiaxial loading. In this study, strain-controlled multiaxial fatigue experiments were conducted on extruded AZ31B magnesium alloy using thin-walled tubular specimens in ambient air. Four loading paths, including fully reversed tension-compression, cyclic torsion, 45° in-phase axial-torsion and 90° out-of-phase axial-torsion, were adopted in the fatigue experiments. It is observed that the strain-life curve displays a distinguishable kink under each loading path at the equivalent strain amplitude around 0.3% to 0.55%. The fatigue life -under the proportional loading path is the highest when equivalent strain amplitudes higher than 0.45%, and the fatigue

    2. Syntheses, crystal structure, and electronic properties of the five ABaMQ4 compounds RbBaPS4, CsBaPS4, CsBaVS4, RbBaVSe4, and CsBaVSe4

      Science.gov (United States)

      Mesbah, Adel; Prakash, Jai; Rocca, Dario; Lebègue, Sébastien; Beard, Jessica C.; Lewis, Benjamin A.; Ibers, James A.

      2016-01-01

      Five new compounds belonging to the ABaMQ4 family were synthesized by solid-state chemistry at 1123 K. The compounds RbBaPS4, CsBaPS4, CsBaVS4, RbBaVSe4, and CsBaVSe4 are isostructural and have the TlEuPS4 structure type. They crystallize in space group D162h - Pnma of the orthorhombic system. Their structure consists isolated MQ4 tetrahedra separated by A and Ba atoms to form a salt-like structure. Density Functional Theory (DFT) calculations of the electronic structures with the use of the HSE functional suggest that the compounds are semiconductors with calculated band gaps of 3.3 eV (RbBaPS4), 3.4 eV (CsBaPS4), 2.3 eV (CsBaVS4), and 1.6 eV (RbBaVSe4).

    3. Structural basis of H2A.Z recognition by SRCAP chromatin-remodeling subunit YL1.

      Science.gov (United States)

      Liang, Xiaoping; Shan, Shan; Pan, Lu; Zhao, Jicheng; Ranjan, Anand; Wang, Feng; Zhang, Zhuqiang; Huang, Yingzi; Feng, Hanqiao; Wei, Debbie; Huang, Li; Liu, Xuehui; Zhong, Qiang; Lou, Jizhong; Li, Guohong; Wu, Carl; Zhou, Zheng

      2016-04-01

      Histone variant H2A.Z, a universal mark of dynamic nucleosomes flanking gene promoters and enhancers, is incorporated into chromatin by SRCAP (SWR1), an ATP-dependent, multicomponent chromatin-remodeling complex. The YL1 (Swc2) subunit of SRCAP (SWR1) plays an essential role in H2A.Z recognition, but how it achieves this has been unclear. Here, we report the crystal structure of the H2A.Z-binding domain of Drosophila melanogaster YL1 (dYL1-Z) in complex with an H2A.Z-H2B dimer at 1.9-Å resolution. The dYL1-Z domain adopts a new whip-like structure that wraps over H2A.Z-H2B, and preferential recognition is largely conferred by three residues in loop 2, the hyperacidic patch and the extended αC helix of H2A.Z. Importantly, this domain is essential for deposition of budding yeast H2A.Z in vivo and SRCAP (SWR1)-catalyzed histone H2A.Z replacement in vitro. Our studies distinguish YL1-Z from known H2A.Z chaperones and suggest a hierarchical mechanism based on increasing binding affinity facilitating H2A.Z transfer from SRCAP (SWR1) to the nucleosome.

    4. Effects of Ca addition on tensile properties and microstructures of hot-extruded AZ91 alloy tube

      Institute of Scientific and Technical Information of China (English)

      WANG Feng; LIU Zheng; YU Bao-yi; ZHANG Kui

      2006-01-01

      As-cast AZ91+XCa (X=0, 0.5%, 1.0%, 1.5%, mass fraction) magnesium alloys were extruded into tube at 380℃ with an extrusion ratio of 6:1. The tensile properties and microstructures of extruded AZ91+XCa alloy tubes were investigated. The microstructural observation indicates that Ca can obviously refine both α-Mg grains and Mg17Al12 phase of AZ91 magnesium alloy. XRD analysis shows that the microstructure of AZ91+0.5Ca alloy consists of α-Mg solid solution and Mg17Al12 phase, while AZ91+1.5Ca alloy contains additionally Al2Ca phase. The tensile experimental results show that for the AZ91 alloy, the addition of Ca has little influence on the ambient temperature tensile properties but can improve the elevated temperature tensile properties. For the extruded AZ91+XCa alloys, the elevated temperature tensile strength decreases, and elongation increases with increasing the Ca content. The improvement in elevated temperature tensile strength of the alloy can be attributed to the presence of a Ca-containing phase, which can increase the microstructural stability of the alloy at elevated temperature.

    5. Effect of Ca, RE elements and semi-solid processing on the microstructure and creep properties of AZ91 alloy

      Energy Technology Data Exchange (ETDEWEB)

      Nami, B. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of); Shabestari, S.G., E-mail: shabestari@iust.ac.ir [Center of Excellence for Advanced Materials and Processing (CEAMP), School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of); Razavi, H. [School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of); Mirdamadi, Sh. [Center of Excellence for Advanced Materials and Processing (CEAMP), School of Metallurgy and Materials Engineering, Iran University of Science and Technology (IUST), Narmak, Tehran (Iran, Islamic Republic of); Miresmaeili, S.M. [Department of Mechanical Engineering, Shahid Rajaee Teacher Training University (SRTTU), Lavizan, Tehran (Iran, Islamic Republic of)

      2011-01-25

      Research highlights: {yields} The size of solid globular {alpha}(Mg) particles decreases in semi-solid slurries of AZ91 alloy by adding Ca and RE elements, whereas it has no considerable effect on the shape factor of the solid particles. {yields} Particle growth in semi-solid slurries of AZ91 and AZRC91 alloys takes place by Ostwald ripening mechanism. {yields} The coarsening rate of solid particles in semi-solid slurries of AZRC91 alloy is lower than that of AZ91 alloy. {yields} Creep properties of AZ91 alloy was improved by adding Ca and RE elements. The thixoformed specimens exhibit the better creep resistance than the as-cast specimens. - Abstract: The effects of calcium and rare earth elements (RE) on the microstructure and creep properties of as-cast and thixoformed AZ91 magnesium alloy have been investigated. It has been shown that the amount of {beta}(Mg{sub 17}Al{sub 12}) intermetallic compound decreases by adding Ca and RE elements into AZ91 alloy and new Al{sub 11}RE{sub 3} and Al{sub 2}Ca intermetallic compounds form in the microstructure. The coarsening of primary {alpha}(Mg) particles in AZ91 alloy and in the Ca and RE containing (AZRC91) alloy takes place by Ostwald ripening mechanism. Adding Ca and RE elements into AZ91 alloy results in a decrease in the coarsening rate of solid particles in semi-solid slurry, whereas it has no visible effect on the shape factor of the solid-particles. The creep properties of AZ91 alloy are improved by adding Ca and RE elements particularly, in the thixoformed condition.

    6. Exciton luminescence in BaFCl crystal

      Energy Technology Data Exchange (ETDEWEB)

      Radzhabov, E

      1998-05-01

      The luminescence spectra and decay characteristics of both 5.45 and 3.4 eV bands in BaFCl oxygen-free crystals were investigated at 5-300 K temperature range using vacuum ultraviolet excitation as well as X-ray excitation. The similarities with excitons in alkali halides allow us to consider both excitons in BaFCl as on-center excitons and strong off-center excitons.

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

      Science.gov (United States)

      Yang, Hee Doo; Kim, Pum-Joon; Eun, Jung Woo; Shen, Qingyu; Kim, Hyung Seok; Shin, Woo Chan; Ahn, Young Min; Park, Won Sang; Lee, Jung Young; Nam, Suk Woo

      2016-03-08

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

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

      Science.gov (United States)

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

      2016-01-01

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

    9. Research status and development tendency of welding technology of AZ31B magnesium alloy%AZ31B镁合金焊接技术研究现状及发展方向

      Institute of Scientific and Technical Information of China (English)

      刘奋军; 王憨鹰

      2013-01-01

      Welding characteristics of magnesium alloy are analyzed,and welding processes of AZ31B magnesium alloy are introduced,including laser welding,brazing,diffusion welding,friction stir welding,TIG,electron beam welding and so on. The future directions of welding technology of AZ31B magnesium alloy are pointed out.%分析镁合金的焊接特点,综述了近年来AZ31B镁合金的焊接方法,包括激光焊、钎焊、扩散焊、搅拌摩擦焊、TIG焊、电子束焊等,展望了AZ31B镁合金的焊接研究方向。

    10. Experimental study of fluoride coating on the degradation of magnesium alloy AZ31B in vitro%氟涂层对AZ31B镁合金植入初期降解作用的影响

      Institute of Scientific and Technical Information of China (English)

      钟丽芳; 李洪洋; 王秋旭; 艾红军

      2011-01-01

      目的 观察氟涂层对AZ31B镁合金植入初期降解速度的影响.方法 分别将无涂层(对照组)和氟涂层(观察组)的AZ31B镁合金浸泡于骨细胞培养基DMEM溶液(模拟体液),分别于浸泡1、3、5、7、14 d时后观察两组模拟体液pH值,扫描电镜下观察两组浸泡前和浸泡7 d时AZ31B镁合金材料表面形貌.结果 对照组镁合金浸泡1、3、5、7、14 d模拟体液pH值分别为7.51±0.15、8.32±0.10、9.36±0.10、9.79±0.09、9.87±0.09,呈升高趋势,观察组分别为7.29±0.07、7.44±0.06、7.47±0.11、7.65±0.11、7.74±0.08,各时点pH值相比,P均>0.05.对照组浸泡前镁合金表面相对光滑,观察组镁合金表面致密、光滑,有一些同向的纹理;浸泡7 d后,无涂层AZ31B镁合金表面呈龟裂状;氟涂层AZ31B镁合金表面无明显改变,可见散在腐蚀凹陷.结论 氟涂层可以在一定程度上抑制AZ31B镁合金植入初期的降解作用.%Objective To study the viability of using magnesium alloy AZ31B coated with fluoride as biodegradable bone scaffolds materials.Methods Pieces of magnesium alloy AZ31B uncoated and coated with fluoride were immersed in DMEM culture medium respectively.The changes of the DMEM culture medium's pH valules and morphology of magnesium alloy AZ31B uncoated or coated were evaluated after immersion.Results The pH values of DMEM solution immersed by magnesium alloy AZ31B uncoated after 1, 3, 5, 7, 14 d were 7.51 ±0.15, 8.32 ±0.10, 9.36 ±0.10, 9.79 ±0.09,9.87 ± 0.09, while that immersed by magnesium alloy AZ31B ooated with flouride were 7.29 ± 0.07, 7.44 ± 0.06, 7.47 ± 0.11,7.65 ± 0.1 1, 7.74 ± 0.08 ( all P > 0.05 ).Before immersed, the surface of magnesium alloy AZ31B was smooth,while magnesium alloy AZ31B coated with fluoride was density and smooth texture.After immersed for 7 d, the surface of magnesium alloy AZ31B uncoated was corroded severely and the surface of magnesium alloy AZ31B coated with fluoride changed a little and

    11. 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.

    12. Study on Deformation and Toughening of AZ31 Magnesium Alloy%AZ31镁合金变形与强韧化研究

      Institute of Scientific and Technical Information of China (English)

      王智文; 李德富; 马志新; 张治民

      2006-01-01

      研究了AZ31镁合金组织的演变过程和力学性能,结果表明:通过挤压变形及动态再结晶,可以显著细化合金晶粒,其尺寸可由约100μm减少到5 μm;二次变形可以提高镁合金的抗拉强度.可见塑性变形是同时实现镁合金构件成形和强韧化的有效途径.

    13. Influence of Hot Deformation on Microstructure of AZ31 Alloy%热变形对AZ31镁合金显微组织的影响

      Institute of Scientific and Technical Information of China (English)

      李峰; 桑玉博; 赵立伟

      2006-01-01

      利用Gleeble1500热模拟材料实验机,在高温不同变形条件下对AZ31镁合金铸态试样进行压缩变形,采用金相显微镜对其组织演变规律进行了分析,结果表明,在350~450℃以10 s-1的应变速率压缩变形可以得到均匀细小的显微组织.

    14. 挤压态AZ31镁合金高周疲劳行为%High Cycle Fatigue Properties of Extruded AZ31 Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      武艳军; 朱荣; 卢田; 王经涛

      2011-01-01

      为探讨镁合金拉/压强度不对称对疲劳性能的影响,对AZ31镁合金进行了室温应力控制疲劳实验,研究应变幅、峰值应变、循环能量参数随周次的演化,并采用光学显微镜观察表面形貌.结果表明:疲劳初期AZ31镁合金滞后环呈现不对称,200周次后不对称消失;峰值压缩应变随周次增加而变小,在约200周次时转变为拉伸应变;裂纹在材料表面孪晶带处形核,并沿孪晶面扩展.由于AZ31镁合金独特的织构与晶格特点,疲劳过程中交替出现的孪生与去孪生导致了滞后环的不对称,孪晶在裂纹形核及扩展中具有重要作用.%A number of uniaxial stress-controlled cyclic loading experiments are conducted for extruded AZ31 magnesium alloy in order to investigate the influence of tension-compression asymmetry on fatigue properties. The cyclic strain amplitude, peak strain and energy parameter are studied. The results show that the hysteresis loops exhibit asymmetry during initial fatigue cycles ,but this asymmetry vanishes after 200 cycles. The peak compressive strain gradually decreases, and it reverses to tensile strain at about 200 cycle. Fatigue crack initiates at the twin bands in the surface,and the crack propagates along with specific twin boundaries. Twining and detwinning behaviors are often observed in the fatigue process due to texture and deformation mechanism, leading to the hysteresis loop asymmetry. The twins are crucial to the crack initiation and propagation.

    15. 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...

    16. Laser cladding of Zr-based coating on AZ91D magnesium alloy for improvement of wear and corrosion resistance

      Indian Academy of Sciences (India)

      Kaijin Huang; Xin Lin; Changsheng Xie; T M Yue

      2013-02-01

      To improve the wear and corrosion resistance of AZ91D magnesium alloy, Zr-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 sliding wear test condition at room temperature. The corrosion resistance of the coating was tested in simulated body fluid. The results show that the coating mainly consists of Zr, zirconium oxides and Zr aluminides. The coating exhibits excellent wear resistance due to the high microhardness of the coating. The main wear mechanism of the coating and the AZ91D sample are different, the former is abrasive wear and the latter is adhesive wear. The coating compared to AZ91D magnesium alloy exhibits good corrosion resistance because of the good corrosion resistance of Zr, zirconium oxides and Zr aluminides in the coating.

    17. Recycling of AZ31 Mg alloy with high purity Mg deposition layer by hot working (solid recycling)

      Energy Technology Data Exchange (ETDEWEB)

      Chino, Y.; Mabuchi, M. [Inst. for Structural and Engineering Materials, National Inst. of Advanced Industrial Science and Technology, Nagoya (Japan); Yamamoto, A.; Iwasaki, H.; Tsubakino, H. [Div. of Materials Science and Engineering, Graduate School of Himeji Inst. of Tech., Himeji (Japan)

      2003-07-01

      Solid recycling of AZ31 Mg alloy with vapor deposition coating layer of high purity Mg was evaluated. In the open die forging experiments, two AZ31 Mg alloy specimens with the pure Mg layer were sufficiently bonded by forging at 673 K. Furthermore, the Al and Zn of the AZ31 substrate diffused up to the center of the pure Mg layer. By the theoretical analysis, it is suggested that the grain boundary diffusion enhanced by grain refinement due to hot forging contributes to the solid state bonding of the specimens. Also, the solid recycled specimen was fabricated from the AZ31 Mg substrate with pure Mg layer by hot extrusion at 673 K. The solid recycled specimen showed almost the same tensile properties as the virgin extruded specimen. This is probably related not only to the grain boundary diffusion but also severe plastic deformation by hot extrusion. (orig.)

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

      Energy Technology Data Exchange (ETDEWEB)

      WHITE, D.A.

      1999-12-29

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

    19. 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

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

    20. Luminescence and scintillation properties of BaY2F8 : Ce3+, BaLu2F8 and BaLu2F8 : Ce3+

      NARCIS (Netherlands)

      van't Spijker, JC; Dorenbos, P; van Eijk, CWE; Jacobs, JEM; den Hartog, HW; Korolev, N

      1999-01-01

      Spectroscopic and scintillation properties of BaY2F8 :Ce3+, BaLu2F8 and BaLu2F8 :Ce3+ are presented. For pure BaLu2F8, a luminescence with a decay time of similar to 1 ns is observed under gamma-ray excitation. This luminescence with a light yield of about 200 ph/MeV is attributed to core-valence lu

    1. Coulomb excitation of levels in /sup 135/Ba and /sup 137/Ba

      Energy Technology Data Exchange (ETDEWEB)

      Dragulescu, E.; Ivascu, M.; Popescu, D.; Semenescu, G. (Institutul de Fizica si Inginerie Nucleara, Bucharest (Romania)); Mihu, R. (Bucharest Univ. (Romania). Dept. of Physics); Velenik, A. (Zagreb Univ. (Yugoslavia). Farmacetsko-Biokemijski Facultet); Paar, V. (Zagreb Univ. (Yugoslavia). Prirodoslovno Matematicki Fakultet)

      1984-08-01

      The low-lying states of /sup 135/Ba and /sup 137/Ba have been studied by means of Coulomb excitation with /sup 14/N, /sup 16/O and ..cap alpha.. particles. Angular distribution measurements were carried out for some transitions in both nuclei with 11.2 MeV ..cap alpha.. particles. Level energies, decay schemes, branching ratios, B(E2) up values and some spin assignments have been established. For the first time B(E2) up values in /sup 137/Ba have been measured and a new level at 1252.5 MeV with spin 7/2/sup +/ was observed. /sup 137/Ba and /sup 135/Ba have been described theoretically by coupling one and three holes, respectively, to the quadrupole vibrations, and rather good agreement with experiment was obtained.

    2. Characterization of Ni–P coating on AZ91D magnesium alloy with surfactants and nano-additives

      Directory of Open Access Journals (Sweden)

      Mohammed Sahal

      2014-12-01

      Full Text Available Direct electroless Ni–P plating was done on AZ91D magnesium alloy by immersing magnesium AZ91D samples into a bath containing Nickel sulphate. The nucleation mechanism of Ni–P deposits on the AZ91D magnesium alloy in the presence of surfactants and nano-additives was studied by using SEM. The electroless Ni–P deposits were preferentially nucleated on the βMg17Al12 phase of AZ91D magnesium alloy. Ni–P coating was coated uniformly in the presence of surfactants. Effect of surfactant C-Tab with varying quantities was studied. Addition of surfactant C-Tab homogenized the Ni–P deposition on AZ91D magnesium alloy surface. The effect produced by surfactant C-Tab was maximum with minimum addition (1 g/l of surfactant C-Tab further increase in the surfactant C-Tab quantity did not brought much changes in morphology. Effect of surfactant SLS was studied using SEM. Surfactant SLS when incorporated in small amounts (6 g/l and 12 g/l only exerted a slight influence in Ni–P deposition on AZ91D alloy surface. However Ni–P deposition was more uniform and spread throughout the surface with the addition of SLS surfactant (18 g/l. Effect of nano additives Al2O3, ZnO, SiO2 were studied. Nano additive Al2O3 enhanced the deposition of Ni–P on AZ91D alloy when added in 0.6 g/l quantity. SiO2 addition also gave the same results. ZnO addition influenced the Ni–P deposition on AZ91D alloy positively. Ni–P surface coating was coated more uniform and spread throughout the surface with the addition of surfactants and nano-additives.

    3. Semi-solid metal processing of aluminum alloy A356 and magnesium alloy AZ91: Comparison based on metallurgical consideration

      Energy Technology Data Exchange (ETDEWEB)

      Kleiner, S.; Beffort, O. [Swiss Federal Laboratories for Materials Testing and Research, EMPA Thun, CH-3602 Thun (Switzerland); Ogris, E.; Uggowitzer, P.J. [Institute of Metallurgy, ETH Swiss Federal Institute of Technology, CH-8092 Zuerich (Switzerland)

      2003-09-01

      Thixocasting or rheocasting of AZ and AM magnesium alloys continues to be a problematic case in semi-solid processing. The comparison with the aluminum thixo alloy A356 shows that the metallurgical and physical properties of the Mg alloy AZ91 are little compatible with this technology: The conclusions from this study are of fundamental importance for future developments in this field of research. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

    4. Roles for H2A.Z and its acetylation in GAL1 transcription and gene induction, but not GAL1-transcriptional memory.

      Directory of Open Access Journals (Sweden)

      Jeffrey E Halley

      Full Text Available H2A.Z is a histone H2A variant conserved from yeast to humans, and is found at 63% of promoters in Saccharomyces cerevisiae. This pattern of localization suggests that H2A.Z is somehow important for gene expression or regulation. H2A.Z can be acetylated at up to four lysine residues on its amino-terminal tail, and acetylated-H2A.Z is enriched in chromatin containing promoters of active genes. We investigated whether H2A.Z's role in GAL1 gene regulation and gene expression depends on H2A.Z acetylation. Our findings suggested that H2A.Z functioned both in gene regulation and in gene expression and that only its role in gene regulation depended upon its acetylation. Our findings provided an alternate explanation for results that were previously interpreted as evidence that H2A.Z plays a role in GAL1 transcriptional memory. Additionally, our findings provided new insights into the phenotypes of htz1Delta mutants: in the absence of H2A.Z, the SWR1 complex, which deposits H2A.Z into chromatin, was deleterious to the cell, and many of the phenotypes of cells lacking H2A.Z were due to the SWR1 complex's activity rather than to the absence of H2A.Z per se. These results highlight the need to reevaluate all studies on the phenotypes of cells lacking H2A.Z.

    5. Roles for H2A.Z and Its Acetylation in GAL1 Transcription and Gene Induction, but Not GAL1-Transcriptional Memory

      Science.gov (United States)

      Halley, Jeffrey E.; Kaplan, Tommy; Wang, Alice Y.; Kobor, Michael S.; Rine, Jasper

      2010-01-01

      H2A.Z is a histone H2A variant conserved from yeast to humans, and is found at 63% of promoters in Saccharomyces cerevisiae. This pattern of localization suggests that H2A.Z is somehow important for gene expression or regulation. H2A.Z can be acetylated at up to four lysine residues on its amino-terminal tail, and acetylated-H2A.Z is enriched in chromatin containing promoters of active genes. We investigated whether H2A.Z's role in GAL1 gene regulation and gene expression depends on H2A.Z acetylation. Our findings suggested that H2A.Z functioned both in gene regulation and in gene expression and that only its role in gene regulation depended upon its acetylation. Our findings provided an alternate explanation for results that were previously interpreted as evidence that H2A.Z plays a role in GAL1 transcriptional memory. Additionally, our findings provided new insights into the phenotypes of htz1Δ mutants: in the absence of H2A.Z, the SWR1 complex, which deposits H2A.Z into chromatin, was deleterious to the cell, and many of the phenotypes of cells lacking H2A.Z were due to the SWR1 complex's activity rather than to the absence of H2A.Z per se. These results highlight the need to reevaluate all studies on the phenotypes of cells lacking H2A.Z. PMID:20582323

    6. 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.

    7. Hot deformation behavior of a spray-deposited AZ31 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      LI Yongbing; CHEN Yunbo; CUI Hua; DING Jie; ZUO Lingli; ZHANG Jishan

      2009-01-01

      The flow stress behavior of an as-spray-deposited AZ31 magnesium alloy with fine grains was investigated by means of compression tests with a Gleeble 1500 thermal mechanical simulator at isothermal constant strain rates of 0.01, 0.1, 1.0, and 10 s-1; the testing temperatures ranged from 623 to 723 K. It is demonstrated that a linear equation can be fitted between the Zemer-Hollomon parameter Z and stress in a double-log scale. The effect of deformation parameters on the behavior of recrystallization was analyzed. Dynamic recrystallization (DRX) generally occurs at a higher temperature and at a lower strain rate. The constitutive equation of the spray-deposited AZ31 magnesium alloy is elevated temperatures due to the fine grain, which provides a large amount of nucleation sites and a high-diffnsivity path for the atom.

    8. Microstructure evolution and effect on mechanical property in AZ80 Mg alloy during thermal processing

      Institute of Scientific and Technical Information of China (English)

      WANG Qiang; ZHANG Zhi-min; LI Bao-cheng; LI Xu-bin

      2006-01-01

      The microstructure and mechanical properties of AZ80 alloy were investigated during thermal processing. The samples of 4 mm in thickness machined from cast ingot were compressed at 300 ℃ with a thickness reduction of 75% and cooled in the water to room temperature. Then ageing(T5) and solution+ageing (T6) treatments were employed respectively. The results show that mechanical properties are significantly improved after thermal processing than those of as-cast AZ80 alloy due to grain refinement and discontinuous precipitates. The heat treatment has significant influence on microstructural evolution for sample formed at moderate temperature. Microstructural evaluation indicates that the β-phase increases because of sufficient solution and the alloy is strengthened evidently.

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

      Science.gov (United States)

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

      2012-12-01

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

    10. 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.

    11. Using two-pass friction stir processing to produce nanocrystalline microstructure in AZ61 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      2009-01-01

      Despite their interesting properties,nanostructured materials have found limited use as a result of the cost of preparation and the difficulty in scaling up.Herein,a two-pass friction stir processing(FSP)technique is employed to refine grain sizes to a nanoscale.Nanocrystalline AZ61 Mg alloy with an av-erage grain size of less than 100nm was successfully obtained using FSP.Corresponding to this,the highest microhardness of the nano-grained region reached triple times that of AZ61 substrate.In prin-ciple,by applying multiple overlapping passes,it should be possible to produce any desired size thin sheet of nanostructure using this technique.We expect that the FSP technique may pave a way to large-scale structural applications of nanostructured metals and alloys.

    12. 激光冲击强化对AZ31和AZ91镁合金表面形貌和电化学腐蚀性能的影响%Effect of laser shock processing on surface morphology and electrochemical corrosion resistance of AZ31 and AZ91 alloys

      Institute of Scientific and Technical Information of China (English)

      张青来; 鲍士喜; 王荣; 钱阳; 张永康; 李兴成

      2014-01-01

      为了研究激光冲击强化对镁合金表面形貌和电化学腐蚀性能的影响,采用电化学方法和钕玻璃脉冲激光(波长1064 nm,脉冲宽度20 ns)研究AZ31热轧板和AZ91-T6铸造镁合金在3.5%NaCl(质量分数)溶液中的动态极化曲线和电化学阻抗谱特征,并对镁合金三维表面形貌、腐蚀试样宏观形貌、自腐蚀电位和电化学阻抗谱进行测试与分析。结果表明:激光冲击改善AZ31热轧板和AZ91-T6镁合金的耐蚀性。当激光功率密度处于0.6~0.9 GW/cm2区间,镁合金腐蚀电位和电流密度分别出现峰值和谷值;当功率密度不小于1.0 GW/cm2时,镁合金腐蚀电位和电流密度分别正负移动,与冲击表面的形变、钝化膜和形貌密切相关。%In order to study the effect of laser shock processing (LSP) on the surface morphology and electrochemical corrosion resistance of magnesium alloys, the dynamic polarization curves and electrochemical impedance spectroscopy (EIS) of specimens of hot rolled sheet of AZ31 alloy and AZ91-T6 cast alloy in 3.5%NaCl (mass fraction) solution were investigated by electrochemical method and Nd:glass laser with the wavelength of 1064 nm and pulse width of 20 ns. The 3D surface morphology, macroscopic morphology of corrosion specimens, corrosion potential and electrochemical impedance spectroscopy (EIS) were also examined and analyzed. The results show that the corrosion resistance of hot rolled AZ31 alloy sheet and AZ91-T6 cast alloy are improved by LSP. When the laser power density is in the range from 0.6 GW/cm2 to 0.9GW/cm2, the peaks and valleys of the corrosion potential and the current density of magnesium alloy appear, respectively. When the power density is not less than 1.0 GW/cm2 , the corrosion potential and current density of magnesium alloy begin to move towards positive and negative directions, respectively, which are closely related to the deformation, passivating film and morphology of the impact

    13. Effect of cerium on ignition point of AZ91D magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      Zhao Hongjin; Zhang Yinghui; Kang Yonglin

      2008-01-01

      The surface and interior temperature-time curves of blocky cerium modified AZ91D magnesium alloy were measured during a non-protective heating and melting process. Two inflection points with rapid increase in temperature were found on both curves, which corresponded to the formation of "auliflower" oxide on the surface and the occurrence of flame during melting. These two temperatures are therefore defined as oxidation point and ignition point, respectively.The interior temperature-time curve is similar to that measured on the surface except for a comparable time delay. The oxidation and ignition temperatures increase with Ce content, an average increase of 33℃ and 61℃ was found when Ce addition was about 1.0 wt %. However, the increasing rate of the oxidation and ignition temperature decreases with increasing Ce content. An addition of 0.6wt% Ce is recommended for ignition-resistant AZ91 magnesium alloy.

    14. Effect of cerium on ignition point of AZ91D magnesium alloy

      Directory of Open Access Journals (Sweden)

      Zhao Hongjin

      2008-02-01

      Full Text Available The surface and interior temperature-time curves of blocky cerium modified AZ91D magnesium alloy were measured during a non-protective heating and melting process. Two inflection points with rapid increase in temperature were found on both curves, which corresponded to the formation of “auliflower”oxide on the surface and the occurrence of flame during melting. These two temperatures are therefore defined as oxidation point and ignition point, respectively. The interior temperature-time curve is similar to that measured on the surface except for a comparable time delay. The oxidation and ignition temperatures increase with Ce content, an average increase of 33=and 61= was found when Ce addition was about 1.0 wt %. However, the increasing rate of the oxidation and ignition temperature decreases with increasing Ce content. An addition of 0.6wt% Ce is recommended for ignition-resistant AZ91 magnesium alloy.

    15. Structure and Corrosion Resistance of Microarc Oxidation Coatings on AZ91D Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      Cui Shihai; Han Jianmin; Li Weijing; Li Ronghua; Zhu Xiaowen; Wang Jinhua

      2004-01-01

      Magnesium alloys are widely used as shells of 3C (computer, mobile phone and consumer electronics) equipments for its impressive mechanical and physical properties, such as low density, good resistance to electromagnetic radiation, suitable for high pressure diecasting and easily recycling, etc. But poor corrosion resistance confines its extensively application. In this paper, protective coatings was successfully prepared on AZ91D magnesium alloys by micro-arc oxidation (MAO) and painting process. Microstructures and phases of MAO coatings were invesgated with scanning electron microscope (SEM) and X-Ray diffractometer. Mechanical properties of MAO coating, such as adhesive force and corrosion resistance, were also tested. Results showed that MAO coatings were a good base for painting process. MAO coatings with paint have good adhesive properties to base metal and excellent corrosion resistance. Micro-arc oxidation with painting process is a good kind of surface treatment to improve the corrosion resistance of mobile phone shell made of AZ91D magnesium alloys.

    16. ENVIRONMENTAL FRIENDLY ANODIZING ON AZ91D MAGNESIUM ALLOYS AND COATING CHARACTERISTICS

      Institute of Scientific and Technical Information of China (English)

      A. Saijo; M. Hino; M. Hiramatsu; T. Kanadani

      2005-01-01

      An environmental friendly anodizing treatment (Anomag) from a phosphate-based solution without heavy metals on AZ91D magnesium alloy was studied. The characteristics of the coatings,such as structure, composition and corrosion resistance were investigated. The effects of this anodizing treatment on the mechanical properties were examined. X-ray diffraction (XRD) analysis revealed that the structure of the coatings is amorphous or glassy. In salt spray tests coatings with an average thickness of 10μm had an anticorrosive performance of over 1000 hours. Fatigue tests revealed that anodizing onto AZ91D magnesium alloy does not affect the fatigue strength. These results demonstrate the utility of this anodizing treatment on magnesium alloy for application as a structural material, such as in the automotive field.

    17. 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.

    18. Mechanical properties and texture evolution in ECAP processed AZ61 Mg alloys

      Energy Technology Data Exchange (ETDEWEB)

      Kim, W.J. [Dept. of Materials Science and Engineering, Hong-ik Univ., Seoul (Korea); Jeong, H.G. [Advanced Mfg. Process Team, Industrial Equipment Technology R and D Center in Korea, Inst. of Industrial Technology, IbJangMyon, ChonAn (Korea)

      2003-07-01

      X-ray diffraction results of the present study show that texture modification occurs during ECAP. The original fiber texture of extruded AZ61 alloy was disintegrated and a new texture was developed gradually by repetitive ECAP pressing. The maximum texture intensity decreased as the pass number increased from 0 up to 2 passes and then increased as the new ECAP texture developed with increasing number of passes. The dominant texture after 8 passes was (10 anti 11)[0 anti 111] + (10 anti 12)[ anti 12 anti 10]. In the eight-passed alloy, the yield stress decreased appreciably compared with that of as-extruded AZ61 alloy, suggesting the texture softening is dominant over the strengthening due to grain refinement. (orig.)

    19. Influencia de la permeabilidad del envase en la calidad del azúcar

      Directory of Open Access Journals (Sweden)

      Aracelia Hernández-Gutiérrez

      2014-01-01

      Full Text Available Se estudia de forma comparativa la velocidad de transmisión de vapor de agua de diferentes materiales para el envase de azúcar empleados en el país, por el método de la hoja volante del Equipo para la "Medición de la Permeabilidad al Vapor de Agua". Se concluye que la velocidad de transmisión de vapor de agua de las bolsas de polietileno de baja densidad, presentan propiedades adecuadas. Se destaca la calidad de la superficie impresa en el papel "Buen día" que presenta una superficie con alta lisura y brillo, de excelente contraste de tintas. Se hace patente además la necesidad una correcta manipulación, envasado y almacenamiento del azúcar en condiciones de humedad y temperatura controladas para mantener sus propiedades organolépticas.

    20. Microstructure and texture evolution during warm compression of the magnesium alloy AZ31

      Institute of Scientific and Technical Information of China (English)

      JIANG Jia; GODFREYB Andy; LIU Qing

      2009-01-01

      The evolution of the microstructure and texture with strain during compression at 150℃ of the mag-nesium alloy AZ31 has been investigated using the electron backscattered diffraction (EBSD) tech-nique. The initial samples were chosen to have a strong basal plane texture with the crystal c-axes perpendicular to the compression direction. The EBSD data provide evidence concerning the relative activity of both {10-12} extension twinning and slip, and suggest that non-basal <c+a> slip is important in samples deformed to a strain of more than 0.2. The relative contributions of the twinning and the slip during deformation have been discussed based on the results above.AZ31, electron backscattered diffraction (EBSD), texture, slip, twinning.

    1. Using two-pass friction stir processing to produce nanocrystalline microstructure in AZ61 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      DU XingHao; WU BaoLin

      2009-01-01

      Despite their interesting properties, nanostructured materials have found limited use as a result of the cost of preparation and the difficulty in soaling up. Herein, a two-pass friotion stir processing (FSP) technique is employed to refine grain sizes to a nanoscale. Nanocrystalline AZ61 Mg alloy with an av-erage grain size of less than 100 nm was successfully obtained using FSP. Corresponding to this, the highest microhardness of the nano-grained region reached triple times that of AZ61 substrate. In prin-ciple, by applying multiple overlapping passes, it should be possible to produce any desired size thin sheet of nanostructure using this technique. We expect that the FSP technique may pave a way to large-scale structural applications of nanostruotured metals and alloys.

    2. Chemical conversion coating on AZ31B magnesium alloy and its corrosion tendency

      Institute of Scientific and Technical Information of China (English)

      Hualan JIN; Xiangjie YANG; Ming WANG

      2009-01-01

      The morphology change of the magnesium matrix after pre-treatment and the mor-phology as well as the phase composition of chemical conversion coating formed by phosphate were studied using scanning electron microscope and X-ray diffraction. The corrosion resistance of the coating was studied by salt spray and damp test, and the corrosion tendency during salt immersion test was analyzed. The results show that the phase composition before and after pre-treatment is almost change- less, and the deep microflaw appears between α and β phases during acidic pickling. The phosphate conversion coating is mainly composed of Mg, MgO, and some amor-phous phase, and it can provide a good protection for the AZ31B alloy. Results from corrosive morphology indicate that the growth and the corrosion resistance of the phosphate conversion coating are related to the forming process of the AZ31B matrix.

    3. Corrosion protection of AZ31 magnesium alloy treated with La3+ modified 3-methacryloxypropyltrimethoxysilane conversion film

      Institute of Scientific and Technical Information of China (English)

      乔英杰; 李文鹏; 王桂香; 张晓红

      2015-01-01

      This study demonstrated the influence of addition concentration of La3+ on the anti-corrosion behavior of a 3-methacry-loxypropyltrimethoxysilane (MPS) film formed on AZ31 magnesium alloy. The morphology and surface chemistry of the samples were evaluated through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The corrosion resistance of the pre-treated AZ31 magnesium alloy was studied during immersion in 0.1 mol/L NaCl solution, using poten-tiodynamic polarization curves and electrochemical impedance spectra (EIS). In comparison to MPS film, the low concentration of La3+ ion modified silane layer exhibited a better anti-corrosion performance, nevertheless, the high concentration of La3+ ion modified was worse. Results showed that the preferable addition concentration of La3+ ion in the silane film was 5×10–4 mol/L in this experi-ment.

    4. Electroless Ni-P plating with a phytic acid pretreatment on AZ91D magnesium alloy

      Energy Technology Data Exchange (ETDEWEB)

      Cui Xiufang, E-mail: cuixf97721@yahoo.com.cn [School of Materials Science and Chemical Engineering, Harbin Engineering University, 145 Nantong St., Harbin 150001 (China); State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China); Jin Guo; Li Qingfen; Yang Yuyun [School of Materials Science and Chemical Engineering, Harbin Engineering University, 145 Nantong St., Harbin 150001 (China); Li Ying [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China); Wang Fuhui [School of Materials Science and Chemical Engineering, Harbin Engineering University, 145 Nantong St., Harbin 150001 (China); State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China)

      2010-05-15

      A phytic acid conversion film with especial functional groups was proposed as the pretreatment layer between Ni-P coating and AZ91D magnesium alloy substrate, to replace the traditional pretreatment. In the process, the silane coupling agent was adopted as connector between conversion film and palladium ion with catalysis. The microstructure of the phytic acid conversion coatings was observed using scanning electronic microscopy, while the composition and functional groups were analyzed by energy dispersive spectrometer and Fourier transform infrared spectroscopy. The bonding between Si-OH of the silane coupling agent and hydroxyl of phytic acid was validated by X-ray photoelectron spectroscopy, and the existence of palladium ion was also verified. The subsequent Ni-P deposited on the layer was also characterized by its structure, morphology, and corrosion resistance. The results show that the Ni-P coatings with the phytic acid pretreatment on AZ91D magnesium alloy have good corrosion resistance.

    5. Jnhmicro-texture of AZ31 Magnesium Alloy in Situ Tracking During Compressing Deformation

      Directory of Open Access Journals (Sweden)

      Wang Zhongtang

      2016-01-01

      Full Text Available Micro-texture evolvement mechanism of AZ31 magnesium alloy during compressing deformation had been studied in situ tracking method by EBSD(Electron backscatter diffraction. The micro-texture at same observation areas, which compressed three times continually at different deformation degree, had been investigated. The results presented that the micro-texture of AZ31 magnesium alloy rolling state is typical (0001 basic texture. When deformation degree was 11% and the temperature was 170ଌ, grains orientation changed remarkably, and most grains had been twined fully and little grains twined partially. The initial basical rolling texture weakened gradually, and twined grains tropism accorded with $ \\lt 10\\bar 10 \\gt $ and 86.3° $ \\lt \\bar 12\\bar 10 \\gt $ orientation.

    6. Magnetic force improvement and parameter optimization for magnetic abrasive polishing of AZ31 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      The magnetic force acting on workpieee to be machined plays a significantly important role in magnetic abrasive polishing process.But in a case of polishing nonferrous materials,the strength of magnetic force is very low and it leads lower polishing efficiency.The magnesium alloy that has superior mechanical properties for industrial application such as a lightweight and high specific strength is one of the most famous nonferrous materials.An improving strategy of the magnetic force for me AZ31 magnesium alloy installed with a permanent magnet was proposed and experimental verification Was carded out.For the proposed strategy,the effect of process parameters on the surface roughness of the AZ31 magnesium alloy Was evaluated by a design of experimental method.

    7. Effect of rolling process on microstructures and mechanical properties of AZ31B alloy sheets

      Institute of Scientific and Technical Information of China (English)

      LE Qi-chi; ZHANG Zhi-qiang; CUI Jian-zhong

      2006-01-01

      AZ31B magnesium extruded slabs prepared from LFEC were rolled at fairly lower temperature at 3, 6 and 16 m/min rolling speeds into 1 mm thickness. The results indicate that the microstructures achieved by rolling at low temperature or at low rolling speed are composed of many prismatic regions divided by shear strips due to pile-up of twin crystals; the prismatic regions increase at elevated rolling temperature or at high rolling speed, and finally all are composed of equiaxed crystals without twin crystals due to dynamic recrystallization. After optimizing control of rolling process, excellent mechanical properties would be acquired. The mechanical properties of AZ31B sheet are σb=350 MPa, σ0.2=300 MPa, and δ=12.0% when rolled at 6 m/min. At the same time, the difference of mechanical properties between transverse and longitudinal direction reduced markedly.

    8. 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.

    9. A novel dual nickel coating on AZ91D magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      Magnesium alloys covered with metal coating display excellent corrosion resistance,wear resistance,conductivity and electromagnetic shielding properties.The electroless plating Ni-P as boRom layer following the electroplating nickel as surface layer on AZ91D magnesium alloy was investigated.The coating surface morphology was observed with SEM and the structure was analyzed with XRD.Electrochemical tests and salt spray tests were carried out to study the corrosion resistance.The experimental results indicate that the dual coating is uniform,compact and pore-free.The adhesion strength between magnesium alloy substrate and electroless plating Ni-P bottom layer and electroplating nickel surface layer is perfect.The corrosion resistance of AZ91D magnesium alloy is greatly improved after being protected with the dual coating.

    10. Study on solid solution and aging process of AZ91D magnesium alloy with cerium

      Institute of Scientific and Technical Information of China (English)

      GUO

      2010-01-01

      The influence of Ce on solid solution and aging process of AZ91D magnesium alloy was analyzed.The results showed that the decomposition of β-Mg17Al12 phase in AZ91D magnesium alloy at 420 ℃ could be completed within 12 h,while this process in the Ce-containing alloy required more time.In subsequent aging process at 175 ℃,Ce obviously delayed the aging process of AZglD.It was inferred that the influence of Ce on process of solid solution and aging was relative to the Ce that existed in β-Mg17Al12 phase of original structure in the form of solid solution,and the interaction of the Ce and Al was an important factor to get process of solution and aging slowly.

    11. Exposiciones: La exposición retrospectiva de Díaz Vargas

      Directory of Open Access Journals (Sweden)

      Francisco Gil Tovar

      1958-11-01

      Full Text Available Miguel Díaz Vargas fue uno de esos pintores honrados que rellenaron -si bien no nutrieron- la pequeña historia del Arte nacional en este siglo. Bogotano, nacido en 1886 y muerto en 1956, discípulo en sus principios de aquel maestro del impresionismo que fue Andrés de Santamaría y formado más tarde en Madrid, de donde regresó para ocupar puesto eminentes en la vida artística colombiana. Díaz Vargas pintó paisajes, bodegones y escenas del "folklore" del país, como era lo obligado para la temática de los naturalistas académicos de su generación.

    12. Effect of samarium on microstructure and corrosion resistance of aged as-cast AZ92 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      吴道高; 颜世宏; 王志强; 张志琦; 苗睿瑛; 张小伟; 陈德宏

      2014-01-01

      The effects of samarium (Sm) on microstructure and corrosion resistance of AZ92 magnesium alloy were characterized and analyzed by scanning electronic microscopy, X-ray diffraction, mass loss test, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy and potentio-dynamic polarization test. The results showed that the added Sm could promote continuous precipitation ofβ-Mg17Al12 phase in grains, and meanwhile restrain discontinuous precipitation of the same phase along the grain boundaries. Thus, the precipitations distributed more uniformly in the aged AZ92 magnesium alloys. When the content of Sm was 0.5 wt.%, the corrosion resistance of aged AZ92 alloy tended to be the best, which was due to theβ-phase distributes more homogeneous reducing the galvanic corrosion. The corrosion product film had more integrality and compactness than AZ92 alloys without Sm. However, it resulted in worse corrosion resistance of AZ92 alloy because of the formation of mass cathodic Al2Sm phase coming from excess Sm in AZ92 alloy.

    13. TIP48/Reptin and H2A.Z requirement for initiating chromatin remodeling in estrogen-activated transcription.

      Directory of Open Access Journals (Sweden)

      Mathieu Dalvai

      2013-04-01

      Full Text Available Histone variants, including histone H2A.Z, are incorporated into specific genomic sites and participate in transcription regulation. The role of H2A.Z at these sites remains poorly characterized. Our study investigates changes in the chromatin environment at the Cyclin D1 gene (CCND1 during transcriptional initiation in response to estradiol in estrogen receptor positive mammary tumour cells. We show that H2A.Z is present at the transcription start-site and downstream enhancer sequences of CCND1 when the gene is poorly transcribed. Stimulation of CCND1 expression required release of H2A.Z concomitantly from both these DNA elements. The AAA+ family members TIP48/reptin and the histone variant H2A.Z are required to remodel the chromatin environment at CCND1 as a prerequisite for binding of the estrogen receptor (ERα in the presence of hormone. TIP48 promotes acetylation and exchange of H2A.Z, which triggers a dissociation of the CCND1 3' enhancer from the promoter, thereby releasing a repressive intragenic loop. This release then enables the estrogen receptor to bind to the CCND1 promoter. Our findings provide new insight into the priming of chromatin required for transcription factor access to their target sequence. Dynamic release of gene loops could be a rapid means to remodel chromatin and to stimulate transcription in response to hormones.

    14. Characterization and wear resistance of macro-arc oxidation coating on magnesium alloy AZ91 in simulated bedy fluids

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      The mechanical characteristics ofthe macro-arc oxidation(MAO) coating on Mg alloy AZ91 were examined by means of nano scratch tester.The corrosion and erosion corrosion behavior of AZ91 with and without MAO coating were investigated by using potentiodynamic electrochemical technique and micro-abrasion tribometer in simulated body fluids,respectively.The influence of HCO3-ions on the erosion corrosion was discussed.The results show that the coating and its substrate are in a pronounced bond.The MAO coating inereases1-2 orders of magnitude of the corrosion resistance of AZ91 alloy.HCO3-ions enhance the corrosion rates of the AZ91 alloys more significantly than the alloys with MAO coating.However,there exists an obvious passivation process of AZ91 without coating in the HCO3-solutions.Moreover,an MgCO3 film formed in HCO3-containing solutions leads to an enhancement in micro-wear resistance.MAO coating deteriorates the erosion corrosion resistance of AZ91 alloy due to the formation of oxidation debris resulted from the broken MAO coating.

    15. Investigation of the passive behaviour of AZ31B alloy in alkaline solutions

      OpenAIRE

      A. Fattah-alhosseini; M. Sabaghi Joni

      2014-01-01

      In this work, the passivity of AZ31B alloy in NaOH solutions was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and Mott–Schottky analysis. Potentiodynamic polarization results indicated that decreasing NaOH concentration leads to decrease the corrosion rate of this alloy. EIS results showed that the reciprocal capacitance (1/C) of the passive film is directly proportional to its thickness which increases with decreasing NaOH concentration. Therefore, it...

    16. AzTEC 1.1 mm OBSERVATIONS OF THE MBM12 MOLECULAR CLOUD

      Energy Technology Data Exchange (ETDEWEB)

      Kim, M. J.; Kim, S.; Youn, S.; Kang, Y.-W. [Department of Astronomy and Space Science, Sejong University, KwangJin-gu, KunJa-dong 98, Seoul 143-747 (Korea, Republic of); Yun, M. S.; Wilson, G. W. [Department of Astronomy, University of Massachusetts, 710 North Pleasant St., Amherst, MA 01003 (United States); Aretxaga, I.; Hughes, D. H.; Humphrey, A. [Instituto Nacional de Astrofisca, Optica y Electronica, Tonantzintla, Puebla (Mexico); Williams, J. P. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Austermann, J. E. [Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, Colorado 80309 (United States); Perera, T. A. [Department of Physics, Illinois Wesleyan University, Bloomington, IL 61701 (United States); Mauskopf, P. D. [School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA (United Kingdom); Magnani, L., E-mail: sek@sejong.ac.kr [Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602-2451 (United States)

      2012-02-10

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

    17. Effects of magnetic fields on the phosphate conversion coating of AZ91D magnesium alloy

      Energy Technology Data Exchange (ETDEWEB)

      Jin Hualan; Peng Wenyi; Guo Hongmin [School of Materials Science and Engineering, Nanchang University, Nanchang 330031 (China); Yang Xiangjie, E-mail: hualanjin@ncu.edu.c [School of Mechanical and Electronic Engineering, Nanchang University, Nanchang 330031 (China)

      2010-01-01

      An external high parallel magnetic fields (MF) was imposed on the barium phosphate process of AZ91D magnesium alloy. The influences of the permanent MF on the morphology, the phase composition and the corrosion resistance of the barium phosphate coatings were studied using scanning electron microscope, X-ray diffraction, salt spay test. The results show that the coatings with MF are more compact, uniform, and smooth, and have better the corrosion resistance than without MF.

    18. Microstructure and Mechanical Behavior of Squeeze Cast SiCw/AZ91 Magnesium Matrix Composites

      Institute of Scientific and Technical Information of China (English)

      2001-01-01

      The interfacial microstructure and tensile properties of the squeeze cast SiCw/AZ91 Mg composites were characterized. There exist uniform, fine and discrete MgO particles at the interface between SiC whisker and magnesium in the composites using acid aluminum phosphate binder. The interfacial reaction products MgO are beneficial to interfacial bonding between SiCw and the Mg matrix, resulting in an improvement of the mechanical properties of the composite.

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

      Science.gov (United States)

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

      2016-10-01

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

    20. AZ31镁合金板材差温拉深数值模拟%Numerical Simulation of Differential Temperature Drawing of AZ31 Magnesium Alloy Sheet

      Institute of Scientific and Technical Information of China (English)

      张小兵; 李建明; 刘伟成

      2013-01-01

      为了获得AZ31镁合金深拉伸的力学性能,在不同温度和应变速率条件下进行了单向拉伸试验.把实验数据导入到Deform-2D软件,采用温差及恒温模型对AZ31镁合金圆筒件拉深工艺进行了模拟.结果表明,温差拉深模型能较好地改善拉深性能;随着拉深速度的增加,拉深深度降低,危险截面产生移动;当速度为1 mm/s时,圆筒件能够顺利成形.在改变冲头温度后,拉深深度随冲头温度的增加而增加.而当冲头温度为60℃时,拉深深度达到最大.

    1. 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.

    2. Mechanical properties of AZ31 alloy processed by a green metallurgy route; Propiedades mecanicas de la aleacion AZ31 procesada por una ruta eco-sostenible

      Energy Technology Data Exchange (ETDEWEB)

      D' Enrico, F.; Garces, G.; Hofer, M.; Kim, S. K.; Perez, P.; Cabeza, S.; Adeva, P.

      2013-07-01

      Recently it has been proved that molding of defect-free components of various commercial alloys of magnesium can be carried out successfully when small amounts of CaO are added to the melt, making unnecessary the use of SF{sub 6} 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 CaAl{sub 2} 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 demonstrated that alloys processed from chips exhibit the highest tensile stress values, close to 320 MPa. (Author)

    3. Preparation of Semi-solid AZ91D Billets by new SIMA Method%新SIMA法制备AZ91D半固态坯

      Institute of Scientific and Technical Information of China (English)

      姜巨福; 彭秋才; 单巍巍; 罗守靖

      2005-01-01

      利用等径道角挤压试验、半固态等温处理试验、金相显微镜、SEM等试验方法和分析设备,对经过等径道角挤压的AZ91D镁合金在等温处理过程中的微观组织演变进行了研究.通过研究,提出了新SIMA制备AZ91D镁合金半固态坯方法.新SIMA法制备的半固态坯料的微观组织均匀,晶粒球化程度好,晶粒细小,平均晶粒尺寸在20~50 μm之间.随着保温时间的延长,新SIMA法制备半固态坯料的微观组织有长大的现象,其可用Ostwald熟化理论描述.随着等温处理温度的升高,晶粒的尺寸先增加后减小,形状系数接近1.随着材料在ECAE中获得的等效应变的增加,半固态坯料的晶粒尺寸减小.

    4. Esquema integrado azúcar, alcohol y levadura forrajera a partir de la caña de azúcar

      Directory of Open Access Journals (Sweden)

      Gustavo Saura

      2005-01-01

      Full Text Available Se muestran las ventajas de emplear esquemas integrados en la producción de azúcar, alcohol y levadura en comparación con la operación aislada de estas instalaciones. Desde el punto de vista de materias primas, la operación integrada reduce significativamente (37 % el déficit de miel final para un ingenio de 5500 t de caña molida/día, asociado con una destilería de 1200 HL/día y una planta de producción de 30 t/día de levadura forrajera. Con relación al balance energético, la integración de los procesos revierte el déficit de electricidad producida (315 Mw en toda la campaña para entregar 780 Mw a la red nacional como electricidad sobrante utilizando como fuente energética el bagazo. Desde el punto de vista del balance económico del complejo productivo, se obtienen reducciones de los costos de producción de US$40.00 t/azúcar, US$7.00 HL/alcohol y US$30.00 t/levadura, si se conducen las producciones de forma integrada.

    5. 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.

    6. 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.; Elliott, M.L.

      1996-10-01

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

    7. Galvanic corrosion behavior of die cast AZ91D magnesium alloy in chloride solution

      Institute of Scientific and Technical Information of China (English)

      Zhensong Tong; Wei Zhang; Jiuqing Li; Jin Gao; Jiquan He; Ji Zhou

      2004-01-01

      The galvanic corrosion behavior of die cast AZ91D magnesium alloy coupled with H62 brass, 316L stainless steel, A3steel and LY12 aluminum alloy of different areas in 3.5% NaC1 solution was studied. The free corrosion potentials, galvanic potentials and currents of these galvanic couples were measured. The galvanic effects were determined by the mass loss and regression method using three points. The results show that: (1) In these four kinds of couples AZ91D acts as the anode, whose galvanic corrosion behavior is mainly controlled by the cathodic polarization; (2) The free corrosion potentials of these four kinds of couples change a liffle with time and cathodic/anodic area ratio (CAAR); (3) The galvanic potential of AZ91D/LY12 moves positively with the increase of time and CAAR; (4) The galvanic currents increase with CAAR, but there is difference in the current change between different couples; (5) The anodic dissolution rate of the magnesium alloy increases by 2-3 orders after being coupled with these four kinds of metals and the galvanic effects of these couples have such a relation as γH62>γ316LS.S>γLY12 >γA3.

    8. Microstructure Formation Mechanism During a Novel Semisolid Rheo-rolling Process of AZ91 Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      Zhanyong ZHAO; Renguo GUAN; Xiang WANG; Chunming LIU

      2013-01-01

      A novel semisolid rheo-rolling process of AZ91 alloy was proposed.The microstructure formation mechanism of AZ91 magnesium alloy during the process was studied.The results reveal that the eruptive nucleation and the heterogeneous nucleation exist.During the grain growth process,the grain breakage took place and transformed into fine spherical or rosette grains on the sloping plate gradually,the other grain growth style is direct globular growth.Due to the secondary crystallization of the remnant liquids in the roll gap,the microstructure of the strip becomes finer with the increment of the casting temperature from 650 ℃ to 690 ℃.But when the casting temperature reached 710 ℃,a part of the liquid alloy transformed into the eutectic phases,and the primary grains ripened to form coarse dendrites.In the casting temperature range from 650 ℃ to 690 ℃,AZ91 alloy strip with fine spherical or rosette grains was prepared by the proposed process.

    9. Simulation of deformation twins and deformation texture in an AZ31 Mg alloy under uniaxial compression

      Energy Technology Data Exchange (ETDEWEB)

      Choi, S.-H. [Department of Materials Science and Metallurgical Engineering, Sunchon National University, Sunchon 540-742 (Korea, Republic of)]. E-mail: shihoon@sunchon.ac.kr; Shin, E.J. [Korea Atomic Energy Research Institute, Neutron Physics Department, Daejeon 305-600 (Korea, Republic of); Seong, B.S. [Korea Atomic Energy Research Institute, Neutron Physics Department, Daejeon 305-600 (Korea, Republic of)

      2007-07-15

      To investigate deformation twins and the evolution of deformation texture during plastic deformation, uniaxial compression tests on a hot-rolled AZ31 Mg alloy were carried out at 200 deg. C. Cylindrical specimens were then compressed in both the rolling and the normal directions. The findings revealed that texture evolution, work hardening and macroscopic anisotropy are strongly dependent on the loading direction. Electron backscattered diffraction analysis was used to examine the orientation of parent grains and twin bands in the AZ31 Mg alloy under uniaxial compression. A viscoplastic self-consistent model (VPSC) was theoretically employed to calculate the relative activities of slip and twin systems in polycrystalline hexagonal aggregates under uniaxial compression. Each deformed grain exhibited an independent number and type of twin variants under uniaxial compression. Neutron diffraction was used to measure the macroscopic texture of the AZ31 Mg alloy. The VPSC model was used to simulate texture evolution, work hardening and macroscopic anisotropy during the uniaxial compression. A modified predominant twin reorientation (PTR) scheme was suggested to explain the gradual increase in twin volume in deformed grains.

    10. Preparation and Corrosion Resistance of Rare Earth Conversion Coatings on AZ91 Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      Xu Yue; Chen Xiang; Lü Zushun; Li Yingjie

      2005-01-01

      The feasibility of forming pollution-free and environmentally benign Ce-based rare earth conversion coatings (short for RECCs) on AZ91 magnesium alloy to enhance corrosion resistance was studied. The effect of optimum processing parameters on corrosion resistance of RECCs, such as density of treating solution, temperature and time of coating formation were discussed. Protective performance of conversion coatings on magnesium alloy was evaluated by moisture/heating test, anodic polarization, etc. The results show that Ce-based RECCs under moisture/heating condition can remain intact, with high coverage and no obvious corrosion phenomenon. Corrosion potential increases and passive phenomenon occurs while current density decreases, therefore Ce-based RECCs can improve corrosion resistance of AZ91 magnesium alloy. The morphology of Ce-based RECCs prepared under optimum process through SEM observation is found to be a few particles coherent to the base coating, and the coating has no cracks and exhibits apparent corrosion resistance during corrosion courses of AZ91 magnesium alloy.

    11. Hydroforming of AZ61A tubular component with various cross sections

      Institute of Scientific and Technical Information of China (English)

      TANG Ze-jun; HE Zhu-bin; LIU Gang; YUAN Shi-jian; HU Lan

      2009-01-01

      The effects of temperature on the mechanical properties and elongation of AZ61A tubular part were derived by uni-axial tension tests at various temperatures. Warm hydroforming of an AZ61A tubular part for passenger car was then numerically and experimentally investigated. The complete processes including bending, pre-forming and hydroforming were analyzed and discussed. Microstructure at the comer of the typical section was observed before and after the final hydroforming process. It is shown that the yielding strength, tensile strength and total elongation increase as temperature increases, while the elongation before necking decreases. The temperature range from 225 ℃ to 250 ℃ is more suitable for hydroforming of the AZ61A magnesium alloy tube with various cross sections. Pre-forming and hydroforming with high strain values are feasible at elevated temperature. Grain refinement is observed at the corner of the part after warm hydroforming. Thinning ratio analysis illustrates that non-uniform deformation at elevated temperature should be considered in process optimization to avoid severe local thinning.

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

      Science.gov (United States)

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

      2016-03-01

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

    13. 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.

    14. AzTEC Millimetre Survey of the COSMOS Field: I. Data Reduction and Source Catalogue

      CERN Document Server

      Scott, K S; Perera, T A; Wilson, G W; Aretxaga, I; Bock, J J; Hughes, D H; Kang, Y; Kim, S; Mauskopf, P D; Sanders, D B; Scoville, N; Yun, M S

      2008-01-01

      We present a 1.1 mm wavelength imaging survey covering 0.3 sq. deg. in the COSMOS field. These data, obtained with the AzTEC continuum camera on the James Clerk Maxwell Telescope (JCMT), were centred on a prominent large-scale structure over-density which includes a rich X-ray cluster at z = 0.73. A total of 50 millimetre galaxy candidates, with a significance ranging from 3.5-8.5 sigma, are extracted from the central 0.15 sq. deg. area which has a uniform sensitivity of 1.3 mJy/beam. Sixteen sources are detected with S/N > 4.5, where the expected false-detection rate is zero, of which a surprisingly large number (9) have intrinsic (de-boosted) fluxes > 5 mJy at 1.1 mm. Assuming the emission is dominated by radiation from dust, heated by a massive population of young, optically-obscured stars, then these bright AzTEC sources have FIR luminosities > 6 x 10^12 L(sun) and star formation-rates > 1100 M(sun)/yr. Two of these nine bright AzTEC sources are found towards the extreme peripheral region of the X-ray clu...

    15. Protective behavior of an SO2/CO2 gas mixture for molten AZ91D alloy

      Directory of Open Access Journals (Sweden)

      Liang Weizhong

      2012-08-01

      Full Text Available The protective behavior for a molten AZ91D alloy in an open melting furnace was investigated under a protective gas mixture containing 3% SO2 and 97% CO2, and the protection mechanism was discussed. Experimental results show that the gas mixture provides effective protection for AZ91D melt in the temperature range from 680 ìC to 730 ìC. The microstructure, chemical composition and phase composition of the surface film formed on the molten AZ91D alloy were analyzed using scanning electron microscopy (SEM with energy dispersive spectrometer (EDS and X-ray diffraction (XRD. The SEM results demonstrate that the surface films with an average thickness between 0.5 レm and 2 レm are dense and coherent in the protected temperature range. The EDS results reveal that the surface film mainly contains elements S, C, O, Al and Mg. The XRD results show that the surface film consists of MgO, MgS and a small amount of C phase.

    16. Precipitation behavior and effect of new precipitated β phase in AZ80 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      TANG Wei; HAN En-hou; XU Yong-bo; LIU Lu

      2006-01-01

      Granular precipitate that was a new kind of β-Mg17Al12 phase found in aged AZ80 wrought Mg alloy at all aging temperature was studied. The structure and precipitation behavior of this granular β-Mg17Al12 precipitate were studied by environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM). The effect of the granular precipitate on mechanical properties of AZ80 alloy was also studied. The new precipitate that was granular and nucleated both on grain boundaries (GBs) and twin boundaries, has the same crystal structure and lattice parameter as those of the continuous or discontinuous precipitated β-Mg17Al12. And the nucleation and growth of the granular precipitate are faster than those of the other two precipitates at higher temperatures (above 583 K), but are suppressed at lower temperatures (below 423 K). At lower temperatures, the discontinuous β-Mg17Al12 precipitates firstly and the granular β-Mg17Al12 precipitates after aged more than 40 h. The crack is easily nucleated on the phase boundaries of granular phase and matrix because of the weak binding force. As a result, the strength and ductility of AZ80 Mg alloy are decreased by the granular β-Mg17Al12 precipitate.

    17. Microstructural formation of semi-solid AZ91D alloy stirred by electromagnetic field

      Institute of Scientific and Technical Information of China (English)

      2005-01-01

      With the help of an electromagnetic stirring device, alloy melt quenching and EBSD (electron back scatter diffraction)analysis technology, the microstructure of the semi-solid AZ91D magnesium alloy slurry stirred by rotational electromagnetic field under different stirring power conditions has been studied. The results show that the size of primary α-Mg phase is reduced obviously when the solidifying alloy melt is stirred by rotational electromagnetic field, moreover, the primary α-Mg grains are changed to fine rosette grains or spherical grains which are proved to belong to the different grains in three-dimension by the EBSD analysis technology. The results also show that the stirring power is an important processing parameter in the preparation of the semi-solid AZ91D magnesium alloy slurry. The larger the stirring power, the finer the primary α-Mg grains, the less the rosette primary α-Mg grains, and the more the spherical primary α-Mg grains. Theoretical analysis indicates that a stronger flow motion leads to a more even temperature field and solute field and a stronger man-made temperature fluctuation in the alloy melt so that the specially fine rosette and/or spherical primary α-Mg grains are formed in the semi-solid AZ91D magnesium alloy slurry.

    18. Effect of neodymium, gadolinium addition on microstructure and mechanical properties of AZ80 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      姜楠; 陈雷; 孟令刚; 房灿峰; 郝海; 张兴国

      2016-01-01

      The microstructure and mechanical properties of AZ80 magnesium alloys with varying Nd, Gd contents were investigated. The results revealed that the as-cast microstructure of AZ80 alloy was composed ofα-Mg matrix and divorced eutecticβ-Mg17Al12 phases. The fraction of Mg17Al12 phase was reduced when 0.6 wt.% Nd was added, and new rod-shaped Al11Nd3 phase and small block-shaped Al-Nd-Mn phase appeared. With Gd addition, the Gd elements mixed with Nd to form rare earth phases. New block-shaped Al2Gd and Al2Nd phases which were collectively called Al2RE phases were observed in the microstructure with more than 0.6 wt.% Gd addition. Moreover, the addition of Gd could promote the precipitation of block-shaped Al2RE phase, and inhibit the original rod-shaped Al11Nd3 phase. The AZ80-0.6Nd-0.6Gd alloy exhibited the optimal mechanical properties among all the ex-perimental alloys, in which the tensile strength, yield strength and elongation were 215, 145 MPa and 8.33%, respectively.

    19. Preparation of biomimetic hydrophobic coatings on AZ91D magnesium alloy surface

      Institute of Scientific and Technical Information of China (English)

      2010-01-01

      The hydrophobic coating has been a promising technology for improving surface performance. The surface performance of magnesium alloy has been limited in application. Furthermore, the hydrophobic of magnesium alloy is rarely investigated because magnesium alloy is an active metal alloy. In this paper, inspired by microstructure character of typical plant leaf surface such as lotus, the biomimetic hydrophobic coatings on AZ91D magnesium alloy surface were prepared by means of wet-chemical combining electroless. The samples were immersed into AgNO3 solution in wet-chemical method firstly. Then, biomimetic hydrophobic coatings were prepared by electroless after wet-method pretreatment. The microstructure was observed by SEM and the contact angles were measured by contact angle tester. The results indicated that the biomimetic hydrophobic coatings with uniform crystalline and dense structure could be obtained on AZ91D magnesium alloy surface. The results of contact angle revealed that the biomimetic nano-composite coatings were hydrophobic. The wet-chemical method treatment on the AZ91D magnesium alloy substrate provided a rough microstructure, thus improving adhesion of the coating and the substrate.

    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. High spin properties of 124Ba

      Indian Academy of Sciences (India)

      K Ilangovan; N Arunachalam

      2002-03-01

      The 124Ba nucleus is investigated on the basis of the method of statistical mechanics by assuming the nucleons to move in triaxially deformed Nilsson potential. The variation in the Fermi energies of protons and neutrons is studied as a function of spin and temperature. The Fermi energies determined as a function of angular momentum is used to study the dependence of shell correction on angular momentum using the Strutinsky smoothing procedure. The most important observation is that the shell correction is almost the same for all spins for 124Ba. The spin cutoff parameter and the single particle level density parameter are studied as a function of spin and temperature. Constant entropy lines drawn by plotting the excitation energy against angular momentum are found to be roughly at constant energy above the yrast line and are almost equally spaced. It is observed that no yrast traps are present for 124Ba.

    2. Effects of Sr,Y on Microstructure and Mechanical Properities of AZ31 Alloy%Sr,Y对AZ31镁合金显微组织与力学性能的影响

      Institute of Scientific and Technical Information of China (English)

      谢卫东; 宁旭; 王春光; 彭晓东

      2011-01-01

      The effects of Sr, Y on the microstructure and mechanical properties of metal mold casting AZ31 alloy were investigated by OM, SEM, EDS, XRD and tensile testing.The results show that the grain of AZ31 alloy can be refined by adding a small amount of Sr and a rod-like phase forms along the grain boundaries.While adding slight Y and Sr into AZ31 alloy, the size of α-Mg grain dramaticlly decreases, Al2Y phase precipitates in the grain and β-Mg17Al12 disappears.With the addition of Sr and Y, the tensile strength at ambient and high temperature obviously enhances.%用金属型铸造法制备了不同Sr、Y含量的AZ31镁合金试样,借助光学显微镜、扫描电镜、能谱分析、XRD、力学性能测试等方法研究了Sr、Y对AZ31镁合金显微组织和力学性能的影响.结果表明,微量Sr的添加可细化AZ31镁合金的显微组织,并且在晶界处有杆状的Al4Sr形成;微量的Sr、Y复合添加可使AZ31镁合金显微组织更加细化,晶内有颗粒状的Al2Y析出,同时β-Mg17Al12相消失;合金的常温和高温力学性能随Sr、Y的添加有明显提高.

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

      Science.gov (United States)

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

      2015-06-16

      The repair of DNA double-strand breaks (DSBs) requires open, flexible chromatin domains. The NuA4-Tip60 complex creates these flexible chromatin structures by exchanging histone H2A.Z onto nucleosomes and promoting acetylation of histone H4. Here, we demonstrate that the accumulation of H2A.Z on nucleosomes at DSBs is transient, and that rapid eviction of H2A.Z is required for DSB repair. Anp32e, an H2A.Z chaperone that interacts with the C-terminal docking domain of H2A.Z, is rapidly recruited to DSBs. Anp32e functions to remove H2A.Z from nucleosomes, so that H2A.Z levels return to basal within 10 min of DNA damage. Further, H2A.Z removal by Anp32e disrupts inhibitory interactions between the histone H4 tail and the nucleosome surface, facilitating increased acetylation of histone H4 following DNA damage. When H2A.Z removal by Anp32e is blocked, nucleosomes at DSBs retain elevated levels of H2A.Z, and assume a more stable, hypoacetylated conformation. Further, loss of Anp32e leads to increased CtIP-dependent end resection, accumulation of single-stranded DNA, and an increase in repair by the alternative nonhomologous end joining pathway. Exchange of H2A.Z onto the chromatin and subsequent rapid removal by Anp32e are therefore critical for creating open, acetylated nucleosome structures and for controlling end resection by CtIP. Dynamic modulation of H2A.Z exchange and removal by Anp32e reveals the importance of the nucleosome surface and nucleosome dynamics in processing the damaged chromatin template during DSB repair.

    4. Intercomparision of Standardized Radioactive Solution of 133Ba

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      <正>133Ba is a very important nuclide in the field of radiation, for example applied to efficienency calibration of the γ spectromenter. To ensure the accurate and reliable of measurement results of 133Ba, to

    5. Incorporation of Ba in Al and Fe pollucite

      Science.gov (United States)

      Vance, Eric R.; Gregg, Daniel J.; Griffiths, Grant J.; Gaugliardo, Paul R.; Grant, Charmaine

      2016-09-01

      Ba, the transmutation product of radioactive Cs, can be incorporated at levels of up to ∼0.07 formula units in Cs(1-2x)BaxAlSi2O6 aluminium pollucite formed by sol-gel methods and sintering at 1400 °C, with more Ba forming BaAl2Si2O8 phases. The effect of Ba substitution in pollucite-structured CsFeSi2O6 was also studied and no evidence of Ba substitution in the pollucite structure via cation vacancies or Fe2+ formation was obtained. The Ba entered a Fe-silicate glass structure. Charge compensation was also attempted with a Cs+ + Fe3+ ↔ Ba2+ + Ni2+ scheme but again the Ba formed a glass and NiO was evident. PCT leaching data showed CsFeSi2O6 to be very leach resistant.

    6. Diversidad genética en variedades de caña de azúcar azúcar (Saccharum spp. usando marcadores moleculares

      Directory of Open Access Journals (Sweden)

      Riascos John J.

      2003-06-01

      Full Text Available Debido a que el conocimiento de la diversidad genética existente en las variedades modernas de caña de azúcar es de vital importancia para los procesos de mejoramiento, el presente estudio examinó 33 variedades usadas por los mejoradores en CENICAÑA, y cinco clones de Saccharum officinarum mediante la técnica de los microsatélites. Se evaluaron 63 iniciadores los cuales produjeron 263 fragmentos polimórficos. Los patrones electroforéticos generados mediante esta técnica fueron analizados usando los paquetes estadísticos SAS (Análisis de Correspondencia Múltiple y NTSYS-pc (dendrograma y matriz de distancias genéticas. Los alelos generados por cada iniciador oscilaron entre 1 y 16 (media de 5. Las agrupaciones generadas mediante estos análisis lograron diferenciar las variedades cultivadas de caña de los clones de S. officinarum, y a su vez determinaron que la similitud promedio de todos los individuos fue 0.664. El análisis de diversidad genética mostró un grupo bastante diverso (Ht: 0.973 y logro identificar 38 genotipos en toda la población. Dentro de los resultados más sobresalientes se destaca la ubicación de la variedad CC 91-1880 muy cerca de las variedades Q provenientes de Australia, proponiendo a esta variedad como un buen candidato para ser analizado por los mejoradores. Los resultados de este trabajo son muy importantes, pues deja claro que a pesar de la homogeneidad genética presente en las variedades modernas de caña de azúcar, existen variantes alélicas que podrían ser utilizadas en los nuevos proyectos de mejoramiento de CENICAÑA. Palabras clave: Caña de azúcar, diversidad genética, microsatélites, marcadores moleculares, Saccharum officinarum.

    7. Nucleon-Pair Shell Model: Magnetic Excitations for Ba Isotopes

      Institute of Scientific and Technical Information of China (English)

      LUO YanAn; NING PingZhi

      2002-01-01

      Magnetic excitations for Ba isotopes are discussed within the nucleon-pair shell model trmicated iti the SDsubspace. With the SD pair determined by a surface-δ interaction, M1 transitions for 1344Ba are well fitted. The M1 andM3 transitions for 132Ba and 130Ba are also predicted. It is shown that the statement, the collective magnetic propertiesarc due to the orbital motion of nucleons, is approximately valid.

    8. Spectroscopy of Ba and Ba$^+$ deposits in solid xenon for barium tagging in nEXO

      CERN Document Server

      Mong, B; Walton, T; Chambers, C; Craycraft, A; Benitez-Medina, C; Hall, K; Fairbank, W; Albert, J B; Auty, D J; Barbeau, P S; Basque, V; Beck, D; Breidenbach, M; Brunner, T; Cao, G F; Cleveland, B; Coon, M; Daniels, T; Daugherty, S J; DeVoe, R; Didberidze, T; Dilling, J; Dolinski, M J; Dunford, M; Fabris, L; Farine, J; Feldmeier, W; Fierlinger, P; Fudenberg, D; Giroux, G; Gornea, R; Graham, K; Gratta, G; Heffner, M; Hughes, M; Jiang, X S; Johnson, T N; Johnston, S; Karelin, A; Kaufman, L J; Killick, R; Koffas, T; Kravitz, S; Krucken, R; Kuchenkov, A; Kumar, K S; Leonard, D S; Licciardi, C; Lin, Y H; Ling, J; MacLellan, R; Marino, M G; Moore, D; Odian, A; Ostrovskiy, I; Piepke, A; Pocar, A; Retiere, F; Rowson, P C; Rozo, M P; Schubert, A; Sinclair, D; Smith, E; Stekhanov, V; Tarka, M; Tolba, T; Twelker, K; Vuilleumier, J -L; Walton, J; Weber, M; Wen, L J; Wichoski, U; Yang, L; Yen, Y -R; Zhao, Y B

      2014-01-01

      Progress on a method of barium tagging for the nEXO double beta decay experiment is reported. Absorption and emission spectra for deposits of barium atoms and ions in solid xenon matrices are presented. Excitation spectra for prominent emission lines, temperature dependence and bleaching of the fluorescence reveal the existence of different matrix sites. A regular series of sharp lines observed in Ba$^+$ deposits is identified with some type of barium hydride molecule. Lower limits for the fluorescence quantum efficiency of the principal Ba emission transition are reported. Under current conditions, an image of $\\le10^4$ Ba atoms can be obtained. Prospects for imaging single Ba atoms in solid xenon are discussed.

    9. Magnetic comparison of BaCa and BaSr substituted hexaferrite powders

      Energy Technology Data Exchange (ETDEWEB)

      Gonzalez-Angeles, A [Alvaro Gonzalez-Angeles, Facultad de IngenierIa, Universidad Autonoma de Baja California, (UABC), Blvd. Benito Juarez s/n, Cp 21280 Mexicali, B. C. (Mexico); Lipka, J; Gruskova, A; Slama, J; Jancarik, V; Slugen, V, E-mail: gangelesa@yahoo.com.m [Faculty of Electrical Engineering and Information Technology, (FEEIT), Slovak University of Technology, (SUT), Ilkovicova 3, 812 19 Bratislava (Slovakia)

      2010-03-01

      Results on magnetic studies of Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12-2x}(ZnTi){sub x}O{sub 19} and Ba{sub 0.75}Ca{sub 0.25}Fe{sub 12-2x}(ZnTi){sub x}O{sub 19}, where x = 0.2 to 0.6, ferromagnetic powders prepared by mechanical alloying are discussed. The structural and magnetic properties of the resulting powders were analyzed by thermo-magnetic analysis, X-ray diffraction, scanning electron microscopy, Moessbauer spectroscopy and magnetic measurements. Curie temperature, T{sub c} decreased dramatically (drop {approx} 39%) for BaCa samples, whilst for BaSr samples remained almost without change (diminution {approx} 2%) at x {<=} 0.2. SEM studies showed that all the particles present nearly hexagonal platelet shape.

    10. AZ31B镁合金表面氟涂层的生物相容性和抗菌性能%Biocompatibility and Antibacterial Property of a Fluoride Coating on AZ31B Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      李绮; 刘新杰; 王泽庆; 颜廷亭; 谭丽丽; 张炳春; 杨柯

      2011-01-01

      采用化学转化方法在AZ31B镁合金表面制备氟涂层,系统研究了氟涂层的表面形貌,体外生物相容性和抗菌性能.结果表明:AZ31B镁合金表面的氟涂层均匀致密;氟涂层镁合金的溶血率明显降低,且无细胞毒性,可满足生物医用材料的要求.同时,氟涂层镁合金的抗凝血性能与316L不锈钢相当,并具有显著的抗菌功能.%A fluoride coating was prepared on AZ31B magnesium alloy by chemical conversion treatment in order to control the biodegradation rate and further increase the biocompatibility of AZ31B alloy. The surface morphology, in vitro biocompatibility and antibacterial property of the coated alloy were investigated in the study. The result showed that the fluoride coating was compact and presented obvious decrease of the hemolytic rate and non- cytotoxicity, meeting the requirement on biomaterials. The result also showed a better behavior against blood coagulation of the coated AZ31B alloy than that of 316L stainless steel, as well as an excellent antibacterial ability.

    11. AZ31镁合金热变形流动应力预测模型%PREDICTED CONSTITUTIVE MODELING OF HOT DEFORMATION FOR AZ31 MAGNESIUM ALLOY

      Institute of Scientific and Technical Information of China (English)

      孙朝阳; 栾京东; 刘赓; 李瑞; 张清东

      2012-01-01

      采用近等温单轴压缩实验获得了AZ31镁合金变形温度为523-723K,应变速率为0.01-10s-1条件下的流动应力,分析了变形温度和应变速率对流动应力的影响规律.结果表明,AZ31镁合金变形过程中发生了动态再结晶,523K时形成细小组织;而723K时动态再结晶和长大的晶粒沿径向拉长.考虑实验过程塑性变形功和摩擦功引起的温度升高,在高应变速率条件下采用温度补偿修正了流动应力.在此基础上,建立了基于双曲正弦模型的峰值流动应力和统一本构关系,该模型利用材料参数耦合应变来描述流动应力的应变敏感性,进一步获得了合金热变形过程中流动应力与变形温度,应变速率和应变的定量关系.采用该本构关系模型预测流动应力具有较高的精度,预测值与实测值相关系数为0.976,平均相对误差为5.07%,实验条件范围内预测的流动应力与实验值几乎能保持一致.%The uniaxial compression tests of AZ31 magnesium alloy at different strain rates of 0.01—10 s-1 and different deformation temperatures of 523—723 K were performed by using Gleeble-1500 simulator with a maximum strain of 0.916. The influences of deformation temperature and strain rate on the flow stress were investigated. The fine microstructure is attributed to dynamic recrystallization during compression process at 523 K. The stretched grains of dynamic recrystallization and growth up along radial direction were founded in microscopic observation at 723 K. Considering plasticity deformation and friction induced temperature rise, the flow stress was corrected at high strain rate by using temperature compensation. The peak flow stress and unified constitutive model were established based on hyperbolic sine model. Strain sensitivity of flow stress was studied to describe the coupling of materials parameters on the strain, and then the relationship between deformation temperature, strain rate and strain

    12. 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)

    13. Research on the Hot-Deformation Characteristics for AZ31 Magnesium Alloy%AZ31镁合金热变形特性研究

      Institute of Scientific and Technical Information of China (English)

      黄光杰; 钱宝华

      2007-01-01

      通过MTS试验机进行等温压缩实验,变形温度范围473~623 K、应变速率范围0.001~1 s-1,研究了AZ31镁合金的流变应力行为及其微观组织的演变规律.结果表明,变形温度、应变速率与峰值应力之间的相互关系可用指数模型来描述,其激活能约为138.13kJ/mol,而动态再结晶则是该合金在热变形过程中的主要软化机制和晶粒细化手段.

    14. AZ31镁合金热压缩变形行为分析%Analysis on Hot Compression Deformation of AZ31 Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      黄蓓蓓; 蔡庆伍; 魏松波; 丁睿; 毛燕

      2007-01-01

      在平面应变条件下研究了不同温度、不同变形速率以及不同变形程度对AZ31镁合金流变应力和组织的影响.结果表明:高温时,由于柱面滑移以及锥面滑移系也被启动,而且发生动态再结晶,导致流变应力显著减小;变形速率增加产生的加工硬化使得流变应力也增加;变形温度和变形速率对镁合金变形过程中孪晶的生成有显著的影响,低温或者是大变形速率下容易生成孪晶.

    15. 802.3az Energy-Efficient Ethernet研究与应用%The Research on 802.3az Energy-Efficient Etherne

      Institute of Scientific and Technical Information of China (English)

      胡莉娜; 刘帆

      2012-01-01

      文章详细介绍了IEEE Std.802.3az-2010 Energy-Efficient Ethernet(EEE,高效能以太网)的工作机制:EEE由物理层的LPI协议实现,在LPI模式下,链路两端设备在链路利用率较低时能进入节能状态,并能在切换LPI模式时不改变链路状态、不出现丢帧、切换时间对上层可以忽略不计;EEE同时规定了链路两端设备交换EEE能力和协商EEE参数的机制.

    16. Microstructure evolution and fracture behavior in superplastic deformation of hot-rolled AZ31 Mg alloy sheet

      Energy Technology Data Exchange (ETDEWEB)

      Yin, D.L.; Zhang, K.F.; Wang, G.F. [School of Material Science and Technology, Harbin Inst. of Tech. (China)

      2005-07-01

      Fine-grained AZ31 magnesium alloy sheets were prepared through hot rolling process. The superplastic properties of hot-rolled AZ31 Mg alloy was examined by uniaxial tensile tests at a temperature range 250{proportional_to}450 C and strain rate range 0.7 x 10{sup -3}{proportional_to}1.4 x 10{sup -1} s{sup -1}. Optical and scanning electronic microscope (SEM) were used to observe the microstructure evolution and fracture behavior in superplastic deformation of AZ31 Mg alloy and the values of deformation activation energy at various temperatures were calculated. It is demonstrated that, the hot-rolled AZ31 alloy begins to exhibit superplasticity from 300 C and a maximum elongation of 362.5% is obtained at 400 C and 0.7 x 10{sup -3} s{sup -1}. In the temperature range 300{proportional_to}400 C, the dominant superplastic deformation mechanism is grain boundary sliding (GBS) controlled by grain boundary diffusion and the influence of temperature on the fracture behavior of AZ31 Mg alloy is characterized by the change from dimple-aggregating type to intercrystalline one. (orig.)

    17. Influence of potassium pyrophosphate in electrolyte on coated layer of AZ91 Mg alloy formed by plasma electrolytic oxidation

      Institute of Scientific and Technical Information of China (English)

      Jin-Young CHO; Duck-Young HWANG; Dong-Heon LEE; Bongyoung YOO; Dong-Hyuk SHIN

      2009-01-01

      The effect of potassium pyrophosphate in the electrolyte on plasma electrolytic oxidation (PEO) process for AZ91 Mg alloy was investigated. The morphologies and chemical compositions of the coating layer on the AZ91 Mg alloy were evaluated and corrosion resistance was also estimated by potentiodynamic polarization analysis. The coating layer on AZ91 Mg alloy coated from the Bath 2 containing 0.03 mol/L of potassium pyrophosphate for 360 s exhibited considerably dense structure and contained 11%-18% (mass fraction) of phosphorous. The higher content of phosphorous of coating layer coated from Bath 2 could be detected at the bottom of oxide layer, which strongly implied that the phosphorous ion might be concentrated at the barrier layer. Corrosion potential of coating layer of AZ91 Mg alloy increased and corrosion current density decreased with increasing the concentration of potassium pyrophosphate. The polarization resistance (Rp) of coating layer of AZ91 Mg alloy coated from Bath 2 was 4.65×107 Ω/cm2, which was higher than that (Rp=3.56×104 Ω/cm2) of the sample coated from electrolyte without potassium pyrophosphate. The coating layer coated from Bath 2 containing 0.03 mol/L potassium pyrophosphate exhibited the best corrosion resistance.

    18. Characterization of plasma electrolytic oxide formed onAZ91 Mg alloy in KMnO4 electrolyte

      Institute of Scientific and Technical Information of China (English)

      Duck-Young HWANG; Ki-Ryong SHIN; Bongyoung YOO; Dong-Heon LEE; Deok-Yong PARK; Dong-Hyuk SHIN

      2009-01-01

      The aim of this work is to investigate microstructure, corrosion resistance characteristics and nanohardness of the oxide layer on AZ91 Mg alloy by applying different voltage with KMnO4 contained solution. There are lots of closed pores that are filled with another oxide compound compared with the typical surface morphology with pore coated until 350 V of coating voltage. The thickness of oxide layer increases with increasing coating voltage. The oxide layer formed on AZ91 Mg alloy in electrolyte with potassium permanganate consists of MgO and Mn2O3. Corrosion potential of the oxide layer on AZ91 Mg alloy obtained at different plasma electrolytic oxidation(PEO) reaction stages increases with increasing coating voltage. The corrosion resistance of AZ91 Mg alloy depends on the existence of the manganese oxide in the oxide layer. The inner barrier layer composed of the MgO and Mn2O3 may serve as diffusion barrier to enhance the corrosion resistance and may partially explain the excellent anti-corrosion performance in corrosion test. Nanohardness values increase with increasing coating voltage. The increase in the nanohardness may be due to the effect of manganese oxide in the oxide layer on AZ91 Mg alloy coated from electrolyte containing KMnO4.

    19. The Beauty of Being a Variant:H2A.Z and the SWR1 Complex in Plants

      Institute of Scientific and Technical Information of China (English)

      Rosana March-D(ī)az; Jose C.Reyes

      2009-01-01

      Numerous studies have shown that the nucleosome is a dynamic structure that strongly influences gene expression.Dynamism concerns different nucleosomal characteristics,including position,posttranslational modifications,and histone composition.Thus,within the nucleosome,canonical histones can be exchanged by histone variant proteins with specific functions-a process known as 'histone replacement'.The histone variant H2A.Z has an important function in transcription and,during the last few years,its role in plant development and immune response has become evident.Compiling genetic and biochemical studies from several laboratories has revealed that plants contain a multiprotein complex,similar to the SWR1/SRCAP complex from yeast and animals,involved in H2A.Z deposition.Despite intense research in different organisms,the mechanism by which H2A.Z influences transcription is still unknown.However,recent results from Arabidopsis have shown a strong inverse correlation between H2A.Z and DNA methylation,suggesting that H2A.Z might protect genes from silencing.

    20. AZ31镁合金与DP980高强钢的纯电塑性效应实验研究%Study on Pure Electroplastic Effect of AZ31 Alloy and DP980 AHSS

      Institute of Scientific and Technical Information of China (English)

      霭振球; 闫磊; 董湘怀

      2015-01-01

      通过单向拉伸试验研究了AZ31镁合金和DP980高强钢两种轻型材料的电塑性效应,研究表明:AZ31镁合金存在纯电塑性效应,而DP980高强钢不存在明显的纯电塑性效应.通过分析峰值电流密度和频率对AZ31镁合金流动应力的影响规律,在Fields-Backofen模型基础上建立了考虑电塑性效应的流动应力方程,此方程能很好的拟合小变形阶段的流变行为.

    1. Influence of Deformation Parameter on Microstructure and Properties of AZ31 Alloy%变形参数对AZ31镁合金组织性能的影响

      Institute of Scientific and Technical Information of China (English)

      张星; 张宝红; 张治民; 王强

      2004-01-01

      AZ31镁合金铸棒在不同变形温度和变形程度下的再结晶行为进行了观察,并测量了各变形条件下的拉伸性能.结果表明,挤压变形及动态再结晶,可以显著的细化铸造AZ31合金的晶粒(由铸态的约100 μm减少到约5 μm).随变形温度的升高,AZ31合金的抗拉强度下降,到一定温度后,趋于稳定.

    2. The Chines BA-VP Structure and its English Translation

      Institute of Scientific and Technical Information of China (English)

      肖音

      2012-01-01

      The Ba-construction is a basic syntactic pattern in modern Chinese, and it is often regarded as one of its characteristic grammatical phenomena. This thesis demonstrates the Ba-VP sentences in details and introduces some suggestive methods to translate the Ba-VP sentences. In English there is no equivalent Ba-VP sentence pattern, thus, when translating Chines Ba-VP sentences into English, we should translate them according to their semantic functions such as “disposition”, “topic/comment” and “causation”。

    3. Sirolimus-eluting dextran and polyglutamic acid hybrid coatings on AZ31 for stent applications

      Science.gov (United States)

      Ma, Jun; Zhao, Nan; Zhu, Donghui

      2016-01-01

      Magnesium (Mg)-based cardiovascular stents are promising candidate as the next generation of novel stents. Clinical studies have revealed encouraging outcomes, but late restenosis and thrombogenesis still largely exist. Blood and vascular biocompatible coatings with drug-eluting features could be the solution to such problems. Objective This study was to investigate the feasibility of a three-layer hybrid coating on Mg alloy AZ31 with sirolimus-eluting feature for cardiovascular stent application. Materials and methods The first and third layers were low molecular weight dextran loaded with sirolimus, and the second layer was polyglutamic acid (PGA) to control sirolimus release. The hybrid coating was verified by scanning electron microscope (SEM). DC polarization and immersion tests were used to evaluate corrosion rate of the materials. Indirect cell viability and cell proliferation tests were performed by culturing cells with extract solutions of AZ31 samples. Blood compatibility was assessed using hemolysis assay. Results Coated samples had an enhanced corrosion resistance than that of uncoated controls, more PGA slower corrosion. Sirolimus had a burst release for the initial ~3 days and then a slower release until reached a plateau. The PGA thickness was able to control the sirolimus release, the thicker of PGA the slower release. The overall cell viability was extract concentration-dependent, and improved by the hybrid coatings. Cell proliferation was correlated to coating thickness and was inhibited by sirolimus. In addition, all coated AZ31 samples were non-hemolytic. Conclusion Results demonstrated that such a three-layer hybrid coating may be useful to improve the vascular biocompatibility of Mg stent materials. PMID:26202889

    4. The relation between severe plastic deformation microstructure and corrosion behavior of AZ31 magnesium alloy

      Energy Technology Data Exchange (ETDEWEB)

      Ben Hamu, G. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Eliezer, D. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Institute of Materials Science and Engineering, TU Clausthal (Germany)], E-mail: deliezer@bgu.ac.il; Wagner, L. [Institute of Materials Science and Engineering, TU Clausthal (Germany)

      2009-01-22

      The quest for ever, higher performance in structural applications has resulted in the outgoing development of new or improved materials with novel crystallographic textures, microstructures, and compositions. However, commercial applicability of such materials depends heavily on the development of economical and robust manufacturing methods. Due to the promise of excellent properties, such as superplasticity, high strength, good ductility, enhanced high cycle fatigue life, and good corrosion resistance, interest has grown in nanostructure bulk materials. Those materials are defined most often as materials exhibiting nanocrystalline grain structures and particle sizes below 100 nm in at least one dimension. In recent years, bulk nanostructure materials processed by methods of severe plastic deformation (SPD) such as equal channel angular extrusion (ECAE) have attracted the growing interest of specialists in materials science. The main object of this research is to compare the microstructural changing and corrosion behavior of magnesium alloy AZ31 after extrusion and severe plastic deformation by ECAE process. The ECAE process can produce intense and uniform deformation by simple shear and provides a convenient procedure for introducing an ultra fine grain size into a material. The samples were prepared by using hot extrusion methods. Hardness and AC and DC polarization tests were carried out on the extruded rods, and the microstructure was examined using optical, electron microscopy (SEM, TEM) and EDS. The results showed that the severe plastic deformation process affected both the microstructure and the corrosion behavior of AZ31 Mg alloy. These results can be explained by the effects of the process on microstructure of AZ31 Mg alloy such as grain size and dislocation density caused by the change in recrystallization behavior.

    5. 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.

    6. 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.

    7. Microstructure evolution in AZ61 alloy processed by equal channel angular pressing

      Directory of Open Access Journals (Sweden)

      Muralidhar Avvari

      2016-05-01

      Full Text Available Magnesium and its alloys are finding increasing use in aerospace, automobile, nuclear, electrical, and structural engineering applications because of their high strength-to-weight ratio when compared to aluminum, titanium, and steel. In this work, AZ61 wrought magnesium alloy was processed using equal channel angular pressing at three different temperatures of 483, 523, and 573 K using up to four equal channel angular pressing passes. A microstructural study was conducted by measuring the average grain size after each pass, for the three different processing temperatures. The mechanical properties of the processed samples were noted to improve due to the reduction in the grain size after each equal channel angular pressing pass. After four equal channel angular pressing passes, the average grain size of the AZ61 samples was found to be reduced to 85%, 81%, and 70% for the pressing temperatures of 483, 523, and 573 K, respectively. The tensile strength of the AZ61 alloy increased with increase in the number of equal channel angular pressing passes for each of the temperatures when compared to as-received alloy. For instance, for the processing temperatures of 483, 523, and 573 K, the tensile strength increased by 24%, 10%, and 12%, respectively, at four equal channel angular pressing passes. Also, the percentage elongation of the alloy was increased with increase in processing temperatures. Moreover, fracture topographies of the tensile surfaces are illustrated through scanning electron microcopy and reveal ductile fracture than as-received alloy for four passes at each equal channel angular pressing processing temperature.

    8. Mechanoluminescence and thermoluminescence of BaFCl:Sm 2+ and BaFBr:Sm 2+ crystals

      Science.gov (United States)

      Brahme, Nameeta; Shukla, M.; Choubey, A. K.; Kurrey, U.; Bisen, D. P.; Dhoble, S. J.

      2012-05-01

      The alkaline-earth fluorohalide crystals MFX, where M=Ca, Sr, Ba, Pb and X=Cl, Br, I, form an important class of materials crystallizing in the PbFCl-type tetragonal structure which is also called the matlockite structure. These compounds have long been of interest because of the various defect species which can be detected by spin resonance and associated techniques. The crystals were prepared by slow cooling of the melt of a stoichiometric mixture of BaF 2 and the corresponding chloride or bromide under 0.2 bar of ultrapure argon (5N5), often slightly fluorinated. We have studied the mechanoluminescence (ML) of BaFBr:Sm 2+ and BaFCl:Sm 2+ crystals. It is seen that after the impact of a moving piston, initially the ML intensity increases with time, attains a maximum value and then it decreases with time up to a particular minimum value, and then it increases again, attaining a peak value and finally disappears. The first peak lies in the deformation region and the second peak lies in the post-deformation region. The ML intensity of the BaFCl:Sm 2+ crystal is much higher than the ML intensity of the BaFBr:Sm 2+ crystal. For different impact velocities, the ML intensity increases with velocity; and the total ML intensity attains a saturation value for higher impact velocities. The total ML intensity increases with the increase in the applied load. It is suggested that the moving dislocation produced during deformation of crystals captures holes from hole-trapped centers (like H centers), and the subsequent radiative recombination of the dislocation holes with electron gives rise to ML. Thermoluminescence (TL) of BaFBr:Sm 2+ and BaFCl:Sm 2+ crystals was studied after exposure to ultraviolet rays with the help of a TLD reader. The peak of TL for the BaFBr:Sm 2+ crystal is found at ∼247°C and for BaFCl:Sm 2+ crystals at 283°C. The TL intensity initially increases with increase in the UV radiation and then it attains saturation for higher values of UV exposure. The

    9. ECAP变形过程中MWCNTs/AZ31复合材料的织构演变%Texture evolution of MWCNTs/AZ31 composite during ECAP

      Institute of Scientific and Technical Information of China (English)

      周国华; 曾效舒; 余志核; 刘焱; 彭路南

      2011-01-01

      Multi-Walled Carbon Nonotubes (MWCNTs) /AZ31 composite was prepared for severe plastic deformation by means of equal channel angular pressing (ECAP) deformation process after hot extrusion. The mechanical proper ties were tested at room temperature. The texture evolution of composites was investigated by X-ray diffractometer (XRD) during ECAP. The results show that the MWCNTs/AZ31 composite has a strong {0001} fiber texture after hot extrusioa The distribution of texture gradually deviates from fiber texture with the increase of ECAP pass num ber, and the texture intensity gradually weakens. The grain size and texture together have an important role on the me chanical properties of MWCNTs/ AZ31 alloy composites at room temperature after ECAP.%采用等径角挤压变形工艺对经热挤压后的MWCNTs/AZ31复合材料进行不同道次的深度塑性变形.测试和分析了复合材料的室温力学性能,并利用X射线衍射仪对复合材料织构的演变进行了分析.研究结果表明:MWCNTs/AZ31复合材料经热挤压后具有较强的{0001}基面纤维织构,随着等径角挤压变形道次的增加,逐渐偏离挤压态的纤维织构分布,并且织构强度也逐渐减弱.MWCNTs/AZ31复合材料的室温力学性能受复合材料晶粒组织大小、织构分布等因素的综合影响.

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

      OpenAIRE

      Peinado, Ana B; Rojo-Tirado, Miguel A; Benito, Pedro J

      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...

    11. Effects of rare earths on friction and wear characteristics of magnesium alloy AZ91D

      Institute of Scientific and Technical Information of China (English)

      祁庆琚; 刘勇兵; 杨晓红

      2003-01-01

      The influence of various rare-earth contents on the friction and wear characteristics of magnesium alloyAZ91D was studied. The results show that the wear resistance properties of rare-earth magnesium alloys are betterthan those of the matrix alloy under the testing conditions. Magnesium alloys undergo transition from mild wear tosevere wear. The addition of rare earths refines the structure of alloys, improves the comprehensive behaviors of themagnesium alloys, increases the stability of oxidation films on worn surfaces, enhances the loading ability of rare-earth magnesium alloys, and delays the transition from mild wear to severe wear effectively.

    12. Semiconducting behavior of the anodically passive films formed on AZ31B alloy

      OpenAIRE

      A. Fattah-alhosseini; M. Sabaghi Joni

      2014-01-01

      This work includes determination of the semiconductor character and estimation of the dopant levels in the passive film formed on AZ31B alloy in 0.01 M NaOH, as well as the estimation of the passive film thickness as a function of the film formation potential. Mott–Schottky analysis revealed that the passive films displayed n-type semiconductive characteristics, where the oxygen vacancies and interstitials preponderated. Based on the Mott–Schottky analysis, it was shown that the calculated do...

    13. Hot deformation mechanisms and microstructural control in high-temperature extruded AZ31 magnesium alloy

      Energy Technology Data Exchange (ETDEWEB)

      Prasad, Y.V.R.K.; Rao, K.P. [Department of Manufacturing Engineering and Engineering Management, City University of Hong Kong, Tat Chee Avenue, Kowloon (China)

      2007-07-15

      A Processing map has been developed for Magnesium alloy AZ31 extruded at 450 C which revealed that the extruded rods may be further processed into components industrially at 400 C and at a strain rate of 10 s{sup -1}. If processed at lower strain rates in the vicinity of 0.1 s{sup -1}, unusual grain size variations with temperature and strain rate are observed, suggesting that grain size control will be difficult. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

    14. Recrystallization during and following hot working of magnesium alloy AZ31

      Energy Technology Data Exchange (ETDEWEB)

      Barnett, M.R. [School of Engineering and Technology, Deakin Univ., Geelong, Vic. (Australia)

      2003-07-01

      The microstructures of magnesium AZ31 are examined following hot compression testing and annealing. The grain size, fraction dynamically recrystallized and, in a couple of cases, the crystallographic texture are reported. It was found that the progress of dynamic recrystallization is strongly sensitive to processing conditions but that the dynamically recrystallized grain size was less sensitive to stress than in other metals. It was also found that, for structures containing between 80 and 95% dynamic recrystallization, abnormal grain growth occurs during annealing. The crystallographic texture produced is also sensitive to the deformation conditions. (orig.)

    15. 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....... The corrosion products for ingot consisted of Mg(OH)(2) with small amounts beta phase, magnesium-aluminum oxide and MgH2 while for die-cast, the product showed a highly amorphous structure. (C) 2000 Elsevier Science Ltd. All rights reserved....

    16. 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.

    17. Desplazamientos, fronteras, memoria: Bernal Díaz del Castillo y el viaje a las Hibueras

      OpenAIRE

      Añón, Valeria

      2010-01-01

      Este trabajo aborda el relato del viaje a las Hibueras que Bernal Díaz del Castillo presenta en su Historia verdadera de la conquista de la Nueva España entendiéndolo como texto cuya indefinición genérica cruza la memoria, la autobiografía, el viaje, la autofiguración. Leemos entonces las estrategias escriturarias por las cuales el relato de este desplazamiento redefine las variables y dinámicas de la exploración, la conquista y la aprehensión de sujetos y espacios otros.

    18. Vida y escritura de bernal díaz del castillo

      OpenAIRE

      Guillermo Serés

      2012-01-01

      A la hora de redactar su excelente crónica, la Historia verdadera de la conquista de la Nueva España, Bernal Díaz del Castillo quiere hacer equiparable la sencillez de estilo con la verdad, con lo que denuncia que la retórica y los que la ofician, los cronistas profesionales, mienten necesaria e irremediablemente. En otras palabras, la estética de la escritura de Bernal, como su vida, se concreta en una identificación de lo bello y lo verdadero: nace por oposición a la de...

    19. Microstructure and texture evolution in multi-pass warm rolled AZ31 magnesium alloy

      Directory of Open Access Journals (Sweden)

      Liu Di

      2015-01-01

      Full Text Available Electron Backscatter Diffraction (EBSD is employed to characterize the microstructure and texture established during the process of warm rolled AZ31 magnesium alloy sheets. The grain size was refined from 17.4 μm to 3.8 μm after 4 pass rolling. Texture of as-rolled sheets was expressed by (0002 basal texture, and the texture intensity was increased with the rolling pass increasing. The mechanical properties of as-rolled sheets were greatly improved by warm rolling.

    20. Influencing factors of surface roughness of MAO ceramic coating on AZ91D

      Institute of Scientific and Technical Information of China (English)

      DI Shi-chun; PAN Ming-qiang; CHI Guan-xin

      2006-01-01

      To investigate the treating parameters' influence on the surface roughness of the MAO ceramic coating on AZ91D, experiments were implemented in the alkaline electrolyte by using a pulse power source with positive and negative pulse, and the surface roughness was measured and analyzed by using a Times roughness-meter and an optical microscope. The machining parameters' influencing rule on the coating surface roughness was investigated. The result indicates that the influence of all parameters is interactive, while the positive voltage and the electrolyte concentration, or increasing the frequency and the positive and negative voltage ratio are appropriate, the coating surface roughness will be improved.

    1. Microstructure of AZ91 alloy deformed by equal channel angular pressing

      Energy Technology Data Exchange (ETDEWEB)

      Braszczynska-Malik, K.N. [Inst. of Materials Engineering, Czestochowa Univ. of Technology, Czestochowa (Poland); Froyen, L. [MTM Dept., Katholieke Univ. Leuven, Leuven-Heverlee (Belgium)

      2005-08-01

      The equal channel angular pressing (ECAP) of the AZ91 magnesium alloy was tested from 553 K to 693 K. The initial grain size of the investigated alloy in homogenized state was about 150 {mu}m. Samples were deformed through a die characterized by an inner contact angle. During the ECAP process the microstructure changed homogeneously and exhibited a decrease of grain size to 10 {mu}m. Transmission electron microscopy allowed the observation of a high dislocation density and large number of twins and shear bands in the deformed material. Some regions in the investigated alloys exhibited a dynamic recrystallisation process. (orig.)

    2. Electrodeposition of a protective copper/nickel deposit on the magnesium alloy (AZ31)

      Energy Technology Data Exchange (ETDEWEB)

      Huang, C.A. [Department of Mechanical Engineering, Chang Gung University, Taoyuan, Taiwan (China)], E-mail: gfehu@mail.cgu.edu.tw; Wang, T.H. [Department of Mechanical Engineering, Chang Gung University, Taoyuan, Taiwan (China); Weirich, T. [Gemeinschaeftslabor fuer Elektronenmikroskopie, RWTH Aachen (Germany); Neubert, V. [Zentrum fuer Funktionswerkstoe GmbH, Clausthal-Zellerfeld (Germany)

      2008-05-15

      An environmental-friendly Cu electrodeposition process was proposed for the Magnesium alloy (AZ 31). Experimental results show that a good bonding between Cu deposit and Mg alloy surface can be achieved with a pretreatment of galvanostatic etching and then copper electrodeposition in the alkaline copper-sulfate plating bath. Microstructures between Cu deposit and Mg alloy substrate were examined with scanning electron and energy-filtering transmission electron microscopes (SEM and EF-TEM). The Cu-deposited Mg alloy can be further electroplated in acidic Cu and Ni plating baths to acquire a protective Cu/Ni deposit.

    3. Relationships between deformation mechanisms and initial textures in polycrystalline magnesium alloys AZ31

      Institute of Scientific and Technical Information of China (English)

      YANG Ping(杨平); CUI Fen-ge(崔凤娥); BIAN Jian-hua(边建华); G Gottstein

      2003-01-01

      Microscopy, X-ray diffractometry and EBSD analysis were applied to inspect the relationships between deformation mechanisms and initial textures in polycrystalline magnesium alloys AZ31. It is found that different deformation mechanisms proceed according to theoretic prediction. Basal slips occur when basal planes of grains are tilted toward normal direction(ND) around transverse direction(TD); prism slips dominate when basal planes are perpendicular to TD. {1012} twinning was favored when basal planes are normal to rolling direction(RD) and {1011} twinning is analyzed to be related to the basal orientation of grains.

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

      Science.gov (United States)

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

      2009-06-01

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

    5. Removal of hydrogen sulfide by sulfate-resistant Acidithiobacillus thiooxidans AZ11.

      Science.gov (United States)

      Lee, Eun Young; Lee, Nae Yoon; Cho, Kyung-Suk; Ryu, Hee Wook

      2006-04-01

      Toxic H2S gas is an important industrial pollutant that is applied to biofiltration. Here, we examined the effects of factors such as inlet concentration and space velocity on the removal efficiency of a bacterial strain capable of tolerating high sulfate concentrations and low pH conditions. We examined three strains of Acidithiobacillus thiooxidans known to have sulfur-oxidizing activity, and identified strain AZ11 as having the highest tolerance for sulfate. A. thiooxidans AZ11 could grow at pH 0.2 in the presence of 74 g l(-1) sulfate, the final oxidation product of elemental sulfur, in the culture broth. Under these conditions, the specific sulfur oxidation rate was 2.9 g-S g-DCW (dry cell weight)(-1) d(-1). The maximum specific sulfur oxidation rate of A. thiooxidans AZ11 was 21.2 g-S g-DCW(-1) d(-1), which was observed in the presence of 4.2 g-SO4(2-) l(-1) and pH 1.5, in the culture medium. To test the effects of various factors on biofiltration by this strain, A. thiooxidans AZ11 was inoculated into a porous ceramic biofilter. First, a maximum inlet loading of 670 g-S m(-3) h(-1) was applied with a constant space velocity (SV) of 200 h(-1) (residence time, 18 s) and the inlet concentration of H2S was experimentally increased from 200 ppmv to 2200 ppmv. Under these conditions, less than 0.1 ppmv H2S was detected at the biofilter outlet. When the inlet H2S was maintained at a constant concentration of 200 ppmv and the SV was increased from 200 h(-1) to 400 h(-1) (residence time, 9 s), an H2S removal of 99.9% was obtained. However, H2S removal efficiencies decreased to 98% and 94% when the SV was set to 500 h(-1) (residence time, 7.2 s) and 600 h(-1) (residence time, 6 s), respectively. The critical elimination capacity guaranteeing 96% removal of the inlet H2S was determined to be 160 g-S m(-3) h(-1) at a space velocity of 600 h(-1). Collectively, these findings show for the first time that a sulfur oxidizing bacterium has a high sulfate tolerance and a high

    6. La quimiometría y la industria del azúcar y sus derivados

      OpenAIRE

      Estrella P. Zayas-Ruiz; Magdalena Lorenzo-Izquierdo; Felipe O. Fragoso-Concepción

      2015-01-01

      Se presentan en el trabajo resultados obtenidos en laaplicación de la quimiometría a diferentes datos expe-rimentales de caracterización de rones cubanos y mie-les finales de caña de azúcar. Se utilizan dos softwarespara estos fines y los principales resultados fueron laidentificación de adulteraciones de rones añejos y añe-jos extra con ron carta blanca, utilizando la espectros-copía ultravioleta visible y la posibilidad de separar eidentificar por regiones de Cuba las mieles finales decaña,...

    7. 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.

    8. Microstructure character of AZ80 magnesium alloy ingots cast under electromagnetic vibration

      Institute of Scientific and Technical Information of China (English)

      GUO Shi-jie; LE Qi-chi; ZHAO Zhi-hao; CUI Jian-zhong

      2007-01-01

      Microstructure evolutions of an AZ80 magnesium alloy ingot with 300 mm in diameter cast with and without the electromagnetic vibration was investigated. The microstructures of the ingot cast with the conventional DC exhibited relatively fine dendritic grains at the surface area, but coarse dendritic grains at the 1/2 radius and large equiaxed dendritic grains at the center. However, under the electromagnetic vibration casting condition, the microstructures of the ingot is significantly refined, especially those at the surface and at the center.

    9. Dynamic recrystallization of AZ91 magnesium alloy during compression deformation at elevated temperature

      Institute of Scientific and Technical Information of China (English)

      李淑波; 王艳秋; 郑明毅; 吴昆

      2004-01-01

      High temperature compressive tests of AZ91 Mg alloy were carried out at 573 -723 K and strain rates of 0. 001 - 1s -1. The microstructures of as-compressed samples were observed by optical microscopy and transmission electron microscopy (TEM), and the microhardness was also tested. It is shown that with the increase of temperature or the decrease of strain rate, the flow stress decreases, at the same time the dynamic recrystallization (DRX)of the alloy is more noticeable. The microstructures reveal that continuous dynamic recrystallization, which develops through conversion of low-angle grain boundaries into high-angle boundaries, occurs preferentially at the grain boundary.

    10. Residual Stresses in Microarc Oxidation Ceramic Coatings on Biocompatible AZ31 Magnesium Alloys

      Science.gov (United States)

      Gu, Yanhong; Xiong, Wenming; Ning, Chengyun; Zhang, Jing

      2012-06-01

      Ceramic coatings have been successfully prepared on biocompatible AZ31 magnesium alloy substrates using microarc oxidation (MAO) technique. Residual stresses attributed to the MgO constituent of the coatings at different oxidation voltages have been evaluated by x-ray diffraction using the sin2 ψ method. It is found that tensile residual stresses were present in the coatings, and they decreased from 1418 to 545 MPa as the oxidation voltages increased from 250 to 350 V. Correlations between the residual stresses and microstructural morphology have been discussed. The residual stress characteristics are attributed to the microcracks and the new phase formation during the MAO process.

    11. 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.

    12. 基于SHPB实验的挤压AZ91D镁合金动态力学行为数值模拟%Numerical simulation of dynamic behavior of extruded AZ91D magnesium alloy based on SHPB experiment

      Institute of Scientific and Technical Information of China (English)

      周霞; 赵昌美; 李利; 黄宏军

      2014-01-01

      Dynamic compression experiments of extruded AZ91D magnesium alloy at three different strain rates were carried out based on split Hopkinson pressure bar (SHPB) technique, and a Johnson-Cook dynamic constitutive equation was obtained by fitting the experimental data. The SHPB dynamic compression of the material was simulated by using LS-DYNA software with the fitted Johnson-Cook constitutive parameters. Calculated incident, reflected, and transmitted waves were correlated with the stress-strain response of the extruded AZ91D sample using two-wave analytical method;the stress-strain curves at different strain rates obtained in the simulations were compared with the experimental and fitted stress-strain responses. The results show that the strain rate sensitivity of the extruded AZ91D Mg alloy increases with increasing the strain rate from 400 s-1 to 1000 s-1. The numerical simulation results and fitted results based on the Johnson-Cook strain-rate dependent constitutive model for the extruded AZ91D Mg alloy are basically in agreement with the experimental results.%使用霍普金森压杆技术对挤压AZ91D镁合金进行3种应变速率下的动态压缩实验,基于实验数据的拟合确定了其动态压缩的Johnson-Cook (J-C)本构方程。采用拟合的J-C本构参数和LS-DYNA有限元软件对挤压AZ91D镁合金在3种应变速率下的SHPB实验进行了数值模拟,根据模拟得到的入射波、反射波和透射波形计算得到各应变速率下完整的应力-应变曲线,并与实验及拟合的应力-应变响应进行了对比。结果表明:当应变速率在400~1000 s-1之间变化时,AZ91D镁合金的应变速率敏感性随应变率增大而增大;基于J-C材料模型描述的AZ91D镁合金应变速率相关的应力-应变本构模型,其数值模拟结果与拟合结果及实验结果基本吻合。

    13. Effects of hot extrusion and annealing treatment on microstructures,properties and texture of AZ31 Mg alloy

      Institute of Scientific and Technical Information of China (English)

      ZHANG Hui; YAN Yun-qi; WENG Wen-ping; ZHONG Hao; CHEN Qi

      2006-01-01

      Effects of extrusion deformation and heat treatment on microstructures, mechanical properties and texture of AZ31 Mg alloy were investigated.The results show that the microstructures of as-cast AZ31 alloy are markedly refined after hot extruding, the average grain size is about 25 μm and strong fiber texture exists in the extruded AZ31 alloy. The mechanical properties are improved obviously. The grain size is somewhat inhomogeneous and strip structure emerges along the extrusion direction due to incomplete dynamic recrystallization during the extrusion process. With increasing annealing temperature, the small grain grows up and turns into equiaxed grain, and the texture is weakened with the visible growing up of grains.

    14. Electroluminescence in BaFCl single crystals

      Energy Technology Data Exchange (ETDEWEB)

      Somaiah, K.; Paracchini, C.

      1987-06-01

      A study of electroluminescence in BaFCl single crystals as a function of temperature is reported. At an excitation voltage of 5 kV, electroluminescent intensity, which is feeble at room temperature, is shown to increase with decreasing temperature. The increase is rapid between 250 K and 175 K and levels off as 80 K is approached. A tentative explanation, in the light of x-ray induced luminescence, is offered. (U.K.).

    15. Hadron Physics in BaBar

      Energy Technology Data Exchange (ETDEWEB)

      Lafferty, G.D.; /Manchester U.

      2005-08-29

      Some recent results in hadron physics from the BaBar experiment are discussed. In particular, the observation of two new charmed states, the D*{sub sJ}{sup +}(2317) and the D*{sub sJ}{sup +}(2457), is described, and results are presented on the first measurement of the rare decay mode of the B meson, B{sup 0} {pi}{sup 0}{pi}{sup 0}.

    16. Microstructure and mechanical properties of friction stir welding of AZ31B magnesium alloy added with cerium

      Institute of Scientific and Technical Information of China (English)

      于思荣; 陈显君; 黄志求; 刘耀辉

      2010-01-01

      The AZ31B magnesium alloy sheet added with 0.5 wt.% Ce was welded with friction stir welding(FSW).The microstructures and mechanical properties of the welded joint were investigated.The results showed that the microstructures in the weld nugget zone were uniform and with small equiaxed grains.The grains in the heat-affected zone and the thermo-mechanical affected zone were coarser than those in the base metal zone and the weld nugget zone.The ultimate tensile strength of AZ31B magnesium alloy added with 0.5...

    17. Improvement of corrosion resistance of AZ31 Mg alloy by anodizing with co-precipitation of cerium oxide

      Institute of Scientific and Technical Information of China (English)

      Salah Abdelghany SALMAN; Ryoichi ICHINO; Masazumi OKIDO

      2009-01-01

      Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated. The chemical composition and phase structure of the coating film were determined via optical microscopy, SEM and XRD. The corrosion properties of the anodic film were characterized by using potentiodynamic polarization curves in 17 mmol/L NaCl and 0.1 mol/L Na2SO4 solution at 298 K. The corrosion resistance of AZ31 magnesium alloy is significantly improved by adding cerium oxide to alkaline solution. In addition, the surface properties are enhanced and the film contains no crack.

    18. New Spectroscopy at BaBar

      Energy Technology Data Exchange (ETDEWEB)

      Mazzoni, M.A.; /INFN, Rome

      2007-04-18

      The Babar experiment at the SLAC B factory has accumulated a high luminosity that offers the possibility of systematic studies of quarkonium spectroscopy and of investigating rare new phenomena. Recent results in this field are presented. In recent times spectroscopy has become exciting again, after the discovery of new states that are not easily explained by conventional models. States such as the X(3872) and the Y(4260) could be new excited charmonium states, but require precise measurements for positive identification. The BaBar experiment [1] is installed at the asymmetric storage ring PEP-II. 90% of the data accumulated by BaBar are taken at the Y(4S) (10.58 GeV) and 10% just below (10.54 GeV). The BaBar detector includes a 5-layer, double-sided silicon vertex tracker and a 40-layer drift chamber in a 1.5 T solenoidal magnetic field, which detect charged particles and measures their momenta and ionization energy losses. Photons, electrons, and neutral hadrons are detected with a CsI(Tl)-crystal electromagnetic calorimeter. An internally reflecting ring-imaging Cherenkov is also used for particle id. Penetrating muon and neutral hadrons are identified by an array of resistive-plate chambers embedded in the steel of the flux return. The detector allows good track and vertex resolution, good particle id and good photon detection so it is especially suited for spectroscopy studies.

    19. The thermodynamic behavior of sulfur in BaO-BaF2 slags

      Science.gov (United States)

      Rachev, Ivan P.; Tsukihashi, Fumitaka; Sano, Nobuo

      1991-06-01

      A gas-slag-metal equilibration technique was used to determine the sulfide capacity of the BaO-BaF2 system at 1473 and 1573 K. The dependence of carbonate capacity on the slag composition was also measured at these temperatures. It was found that the BaO-BaF2 system has the highest sulfide capacities among the fluxes which are of metallurgical interest. The dependence of sulfide and carbonate capacities on the partial pressure of O2 and CO2 was also investigated. The partial pressure of CO2 proved to have a strong effect on these values at the investigated temperatures. The influence of temperature on the sulfide and carbonate capacities was studied in the temperature range between 1423 and 1623 K. The data for sulfide and carbonate capacities were correlated in order to check if the carbonate capacity can be used as a measure of basicity of slags. It was found that the carbonate capacity can be used as a representative measure of the slag basicity at low contents of BaO and at temperatures higher than 1623 K when the carbonate dissolution into the slag is low and the ratio of the activity coefficient of a sulfide ion to that of a carbonate ion is independent of slag composition.

    20. 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.

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

      Science.gov (United States)

      Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan

      2013-11-01

      Bio-absorbable magnesium (Mg) based alloys have been introduced as innovative orthopedic implants during recent years. It has been specified that rapid degradation of Mg based alloys in physiological environment should be restrained in order to be utilized in orthopedic trauma fixation and vascular intervention. In this developing field of healthcare materials, micro-arc oxidation (MAO), and MgF2 conversion coating were exploited as surface pre-treatment of AZ91 magnesium alloy to generate a nanostructured hydroxyapatite (n-HAp) coating via electrophoretic deposition (EPD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) techniques were used to characterize the obtained powder and coatings. The potentiodynamic polarization tests were carried out to evaluate the corrosion behavior of the coated and uncoated specimens, and in vitro bioactivity evaluation were performed in simulated body fluid. Results revealed that the MAO/n-HAp coated AZ91 Mg alloy samples with a rough topography and lower corrosion current density leads to a lower Mg degradation rate accompanied by high bioactivity.

    2. AzTEC 1.1 mm Observations of the MBM12 Molecular Cloud

      CERN Document Server

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

      2011-01-01

      We present 1.1 mm observations of the dust continuum emission from the MBM12 high-latitude molecular cloud observed with the Astronomical Thermal Emission Camera (AzTEC) mounted on the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. We surveyed a 6.34 deg$^2$ centered on MBM12, making this the largest area that has ever been surveyed in this region with submillimeter and millimeter telescopes. Eight secure individual sources were detected with a signal-to-noise ratio of over 4.4. These eight AzTEC sources can be considered to be real astronomical objects compared to the other candidates based on calculations of the false detection rate. The distribution of the detected 1.1 mm sources or compact 1.1 mm peaks is spatially anti-correlated with that of the 100 micronm emission and the $^{12}$CO emission. We detected the 1.1 mm dust continuum emitting sources associated with two classical T Tauri stars, LkHalpha262 and LkHalpha264. Observations of spectral energy distributions (SEDs) indicate that LkHalpha262 ...

    3. 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.

    4. Microstructure and mechanical properties of hot-extruded AZ31 powders

      Energy Technology Data Exchange (ETDEWEB)

      Matsuzaki, K.; Hatsuakno, K.; Hanada, K.; Shimizu, T. [National Inst. of Advanced Industrial and Science Technology(AIST), Tsukuba (Japan); Sano, T. [Chiba Inst. of Tech., Narashino (Japan)

      2003-07-01

      AZ31 alloy powder was prepared by gas-atomization and consolidated into a round bar by hot extrusion at temperatures of 573 K and 623 K with extrusion ratios of 1:10 and 1:20. The extruded AZ31 alloy powders consist of fine grain with an average grain size of 10 {mu} m and show a high tensile strength of 340 MPa with an elongation of about 18% at room temperature. The compression test at elevated temperatures reveals that the sample extruded with extrusion ratio of 1:20 was easily deformed to a forming degree of 0.6 without fracture at temperatures above 423 K and have a good formability. On the contrast, the extruded sample with an extrusion ratio of 1:10 shows cracks after deformation. The extrusion ratio plays an important role on the formability. It is said that the powder metallurgical processing is useful to produce a high strength Mg alloys with a good formability at temperatures above 423 K. (orig.)

    5. Patria y nación en la época de Porfirio Díaz

      Directory of Open Access Journals (Sweden)

      Enrique Florescano

      2005-01-01

      Full Text Available 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 se da una imagen de México basado en el pasado precolombino, prospero en el presente y proyectado al futuro. La construcción de la idea de Patria, la forja de la Nación y la reforma de la educación fueron objetivos fundamentales en la política de Díaz.

    6. 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.

    7. Friction stir welding of AZ31 magnesium alloys processed by equal channel angular pressing

      Institute of Scientific and Technical Information of China (English)

      ZHANG Bing; YUAN Shouqian; WANG Xunhong

      2008-01-01

      Equal channel angular pressing (ECAP) is an effective thermo-mechanical process to make ultrafine grains.An investigation was carried out on the friction stir welding (FSW) of ECAPed AZ31 magnesium alloys with a thickness of 15 mm.For different process parameters,the optimum FSW conditions of ECAPed AZ31 magnesium alloys were examined.The basic characterization of weld formation and the mechanical properties of the joints were discussed.The results show that the effect of welding parameters on welding quality was evident and welding quality was sensitive to welding speed.Sound joints could be obtained when the welding speed was 37.5 mm/min and the rotation speed of the stir tool was 750 r/min.The maximum tensile strength (270 MPa) of FSW was 91% that of the base materials.The value of microhardness varied between advancing side and retreating side because of the speed field near the pin of the stir tool,which weakened the deformed stress field.The value of microhardness of the welding zone was lower than that of the base materials.The maximum value was located near the heat-affected zone (HAZ).Remarkable ductile character was observed from the fracture morphologies of welded joints.

    8. 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.

    9. Deformation behaviors of magnesium alloy AZ31 sheet in cold deep drawing

      Institute of Scientific and Technical Information of China (English)

      YANG Lian-fa; MORI Ken-ichiro; TSUJI Hirokazu

      2008-01-01

      To investigate how the popular magnesium alloy AZ31 sheet (aluminum 3%, zinc 1%) behaves in cold working, deep drawing experiments at room temperature, along with finite element(FE) simulation,were performed on the cold forming sheet of the AZ31 alloy after being annealed under various conditions. The activities were focused on the fracture pattern, limit drawing ratio(LDR), deformation load, thickness distribution, anisotropic effect, as well as the influences of the annealing conditions and tool configuration on them. The results display that punch shoulder radius instead of die clearance, has much influence on the thickness distribution. The anisotropy is remarkable in cold working, which adversely impacts the LDR. The fracture often happens on the side wall at an angle to axis of the deformed specimen. The results also imply that the LDR for the material under present experimental conditions is 1.72, and annealing the material at 450 ℃ for 1 h may be preferable for the cold deep drawing.

    10. High cycle fatigue properties of die-cast magnesium alloy AZ91D-1%MM

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      The high cycle fatigue properties of the die-cast magnesium alloy AZ91D containing 1%mischmetal(mass fraction)at a fatigue ratio of 0.1 were investigated.The difference in the microstructure between the skin and core region of the die-cast magnesium alloy was analyzed by optical microscopy.The mechanical property tests indicate that the values of the tensile strength,elongation and hardness are 185 MPa,1.5%and HBS 70±3 at room temperature,respectively.The p-S-N curve(p=50%)of the die-cast magnesium alloy AZ91D-1%MM is determined and the mean fatigue strength corresponding to 3.8×105cycles is 70 MPa.A linear relation between S and Np in log scale between 103 and 106 cycles is written with a equation.The mechanical properties are influenced by the casting defects.The fatigue life of the samples with minor defects is near to the upper limit of the fatigue life data.The fatigue fracture surface of the samples with minor defects possesses the mixed characteristics of quasi-cleavage,lacerated ridge and dimple and it is briule fracture mode as a whole.

    11. In Vivo Corrosion Resistance of Ca-P Coating on AZ60 Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      Xing Xiao; Haiying Yu; Qingsan Zhu; Guangyu Li; Yang Qu; Rui Gu

      2013-01-01

      Magnesium-based alloys are frequently reported as potential biodegradable orthopedic implant materials.Controlling the degradation rate and mechanical integrity of magnesium alloys in the physiological environment is the key to their applications.In this study,calcium phosphate (Ca-P) coating was prepared on AZ60 magnesium alloy using phosphating technology.AZ60 samples were immersed in a phosphating solution at 37 ± 2 ℃ for 30 min,and the solution pH was adjusted to 2.6 to 2.8 by adding NaOH solution.Then,the samples were dried in an attemperator at 60 ℃.The degradation behavior was studied in vivo using Ca-P coated and uncoated magnesium alloys.Samples of these two different materials were implanted into rabbit femora,and the corrosion resistances were evaluated after 1,2,and 3 months.The Ca-P coated samples corroded slower than the uncoated samples with prolonged time.Significant differences (p < 0.05) in mass losses and corrosion rates between uncoated samples and Ca-P coated samples were observed by micro-computed tomography.The results indicate that the Ca-P coating could slow down the degradation of magnesium alloy in vivo.

    12. Microstructure and property of zinc phosphate coating on die-casting magnesium alloy AZ91D

      Institute of Scientific and Technical Information of China (English)

      LI Guang-yu; LIAN Jian-she; NIU Li-yuan; JIANG Zhong-hao

      2006-01-01

      A surface treatment method was described, which can form a uniform and dense phosphate conversion coating on the die -casting magnesium alloy AZ91D in a non-chromate and non-nitrite bath. The coating consists of Zn3(PO4)2-4H2O, Zn, AlPO4 and MgZn2(PO4)2 analyzed by XRD. The SEM results show that the microstructure of the zinc phosphate coating transfers from flower-like to slab-like crystals with the increase of immersion time of magnesium alloy samples in the phosphating bath. The zinc phosphate coating formed in the bath with immersion time of 1 min is denser because metallic Zn and insoluble phosphate crystals co-deposit on the magnesium alloy surface and the growth of the crystals are restricted by each others. The zinc phosphate coating on the magnesium alloy is used as the base layer for further cataphoric and powder paintings. The cataphoric painting on AZ91D alloy based on phosphate coating has similar adhesion and corrosion-resistance to that based on the chromate conversion coating. But for powder painting, the former exhibits better adhesion property than the latter, due to the uneven microstructure and the enough thickness of the phosphate coating.

    13. 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.

    14. Research on Thermal Deep-drawing Technology of Magnesium Alloy(AZ31B) Sheets

      Institute of Scientific and Technical Information of China (English)

      Sfihong ZHANG; Kun ZHANG; Zhongtang WANG; Chuanfu YU; Yi XU; Qiang WANG

      2004-01-01

      Forming technology of Mg alloy (AZ31B) sheets can be investigated by thermal deep drawing experiments. In the experiments,the blank holder and die contacting with the blank were heated to the same temperature as the blank by using the heating facility. The circular blank heated in an oven is formed at a temperature range of 100~400℃ to obtain the optimum forming temperature range and the effects of major technical parameters on the workpiece quality. It is found that the blank is brittle at temperatures lower than 200℃. Temperatures higher than 400℃ are not suitable for forming of the sheets because of severe oxidation and wrinkling. AZ31B shows an excellent formability at temperatures from 300 to 350℃ and can be formed into a workpiece with good quality. When the blank holder force is 99 Kn, extruded sheets with a thickness of 1 mm can be formed into cups without wrinkling. Workpieces show strong anisotropic deformation behavior on the flanges.

    15. Newton method for the optimization of a new constitutive equation for the plastic flow dependent on the strain. Application to magnesium alloys AZ80 and AZ61; El metodo de Newton para la optimizacion de una nueva ecuacion constitutiva para la fluencia plastica dependiente de la deformacion. Aplicacin a las aleaciones de magnesio AZ80 y AZ61

      Energy Technology Data Exchange (ETDEWEB)

      Gutierrez, V.; Roeorp, R.; Carsi, M.; Ruano, O. A.

      2013-07-01

      A new numerical algorithm has been developed, based on Newton's method, for optimizing the parameters of a new strain dependent constitutive equation, based on the Garofalo equation. The adjustment is direct, with second order algorithms, for an equation derived from that of Garofalo with a nonlinear objective function. This new optimization algorithm has been applied to creep data of two magnesium alloys AZ80 and AZ61, having an unusual plastic behavior. A certain pseudo-stationary exists in the curves studied, in the sense that the usual deformation states are not manifested in an obvious way. The parameters of the new constitutive equation, dependent on strain, have been determined for these alloys. For analyzing the precision of the parameters and the accuracy of modeling of the stress-strain curves, a statistical treatment has been applied which allows assessing the quality of the constitutive equation proposed and the consistency of these parameters. Stress-strain curves have been compared with the modeling results, reaching a good agreement between the experimental data and the resulting modeling. (Author)

    16. Synthesize of AZ31/TiC magnesium matrix composites using friction stir processing

      Directory of Open Access Journals (Sweden)

      M. Balakrishnan

      2015-03-01

      Full Text Available Friction stir processing (FSP is a novel solid state technique to synthesize metal matrix composites. In the present work, an attempt has been made to synthesize AZ31/TiC magnesium matrix composites using FSP and to analyze the microstructure using scanning electron microscopy. A groove was prepared on 6 mm thick AZ31 magnesium alloy plates and compacted with TiC particles. The width of the groove was varied to result in four different volume fraction of TiC particles (0, 6, 12 and 18 vol.%. A single pass FSP was carried out using a tool rotational speed of 1200 rpm, traverse speed of 40 mm/min and an axial force of 10 kN. Scanning electron microscopy was employed to study the microstructure of the synthesized composites. The results indicated that TiC particles were distributed uniformly in the magnesium matrix without the formation of clusters. There was no interfacial reaction between the magnesium matrix and the TiC particle. TiC particles were properly bonded to the magnesium matrix.

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

      Energy Technology Data Exchange (ETDEWEB)

      Pan Fusheng [College of Materials Science and Engineering, Chongqing University, Chongqing, 400044 (China); Yang Xu, E-mail: yangxu2524@yahoo.com.cn [College of Materials Science and Engineering, Chongqing University, Chongqing, 400044 (China); Chemistry Department, Third Military Medical University, Chongqing, 400038 (China); Zhang Dingfei [College of Materials Science and Engineering, Chongqing University, Chongqing, 400044 (China)

      2009-07-30

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

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

      Science.gov (United States)

      Pan, Fusheng; Yang, Xu; Zhang, Dingfei

      2009-07-01

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

    19. Project W-151 Tank 101-AZ Waste Retrieval System Year 2000 Compliance Assessment Project Plan

      Energy Technology Data Exchange (ETDEWEB)

      BUSSELL, J.H.

      1999-08-02

      This assessment describes the potential Year 2000 (Y2K) problems and describes the methods for achieving Y2K compliance for Project W-151, Tank 101-AZ Waste Retrieval System. The purpose of this assessment is to give an overview of the project. This document will not be updated and any dates contained in this document are estimates and may change. Two mixer pumps and instrumentation have been or are planned to be installed in waste tank 101-AZ to demonstrate solids mobilization. The information and experience gained during this process test will provide data for comparison with sludge mobilization prediction models and provide indication of the effects of mixer pump operation on an Aging Waste Facility tank. A limited description of system dates, functions, interfaces, potential Y2K problems, and date resolutions is presented. The project is presently on hold, and definitive design and procurement have been completed. This assessment will describe the methods, protocols, and practices to ensure that equipment and systems do not have Y2K problems.

    20. Forming of a super plastic sheet metal made of MgAZ31 alloy

      Science.gov (United States)

      Zaid, Adnan I. O.; Al-Matari, Mustafa A. A.; Nazzal, M. A. H.

      2016-08-01

      Metal forming industries are constantly looking for advanced innovation, economical and energy efficient techniques. Superplastic forming has a great potential to be one of those advanced forming methods. It is a near net shape forming process which uses a unique type of materials where elongation exceeds 200% during a controlled forming conditions, e.g. temperature, pressure, and strain rate. Most of superplastic materials are formed by gas technique at elevated temperature. The main objectives of the research work in this paper were: to study the effects of the forming schemes on the forming time and thickness distribution of the formed and device a method to improve the forming part thickness and its uniformity distribution and the forming time. In this paper, a hydraulic and heating system were designed and manufactured to facilitate the experimental investigation. The superplastic magnesium alloy AZ31, Mg AZ31, was formed at 350°C with different strain rates to investigate the effect of the forming pressure profiles on the thickness uniformity of the superplastic formed part. The pressure profiles were generated based on Dutta and Mukherjee analytical approach. Finally, a variable strain rate method is modified to improve the uniformity of the thickness distribution of the formed part and reduce the forming time; which is a major limitation of superplastic forming.

    1. 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.

    2. 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.

    3. INVESTIGATION OF LASER BEAM WELDING PROCESS OF AZ61 MAGNESIUM-BASED ALLOY

      Institute of Scientific and Technical Information of China (English)

      H.Y. Wang; Z.J. Li

      2006-01-01

      Laser welding process of AZ61 magnesium alloys is investigated using a special CO2 laser experimental system. The effect of processing parameters including laser power, welding speed,and protection gas flow at the top and bottom is researched The results show that an ideal weld bead can be formed by choosing the processing parameters properly. An optimized parameter range is obtained by a large number of experiments. Among them, laser power and welding speed are the two main parameters that determine the weld width and dimensions. The protect gas flow rate has a slight effect on the weld width, but it directly effects the surface color of the weld. The test results for typical welds indicate that the microhardness and tensile strength of the weld zone are better than that of the base metal. A fine-grained weld region has been observed and no obvious heat-affected zone is found. The weld zone mainly consists of small α-Mg phase, (α +Al12Mg17), and other eutectic phases. The small grains and the eutectic phases in the joint are believed to play an important role in the increase of the strength of welds for AZ61 magnesium alloys.

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

      Science.gov (United States)

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

      2017-02-01

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

    5. 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

    6. Plastic anisotropy and fracture behavior of AZ31 magnesium alloy%AZ31镁合金的各向异性及断裂行为

      Institute of Scientific and Technical Information of China (English)

      刘培; 信运昌; 刘庆

      2011-01-01

      研究织构和异常长大晶粒对热轧AZ31镁合金力学各向异性和断裂行为的影响.在拉伸轴与板材的法向方向分别呈0°、15°、30°、45°、60°、75°和90°下进行单轴拉伸实验,观察不同角度下样品的拉伸各向异性.结果表明:由于{1012}孪晶的出现,在0°-30°时样品表现出较低的屈服强度;当角度大于45°时,样品的主要的变形机制为基面和柱面滑移;当角度低于60°时,宏观断口平行于大晶粒拉长的方向;在75°和90°时样品的宏观断口呈锯齿状.%The effects of texture and abnormal large grains on the plastic anisotropy and fracture behavior of hot-rolled AZ31 magnesium alloy were investigated. Uniaxial tensile deformation behaviors of samples with tensile axis tilting 0°, 15°, 30° 45°, 60°,75° and 90° to normal direction (ND) respectively were addressed. Tensile deformation anisotropy was observed for samples with different angles to ND. The results show that the specimens with the angle from 0~ to 30~ exhibit relatively lower yielding strength due to the {1012} extension twinning. However, basal slip and prismatic slip are the dominant deformation modes for the specimens with angles larger than 45°. Macro-fractures are parallel to the length direction of abnormal large grains in the specimens with angles less than 60°, while those are serrated fracture edge for specimens with angles 75° and 90°.

    7. 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

    8. Effect of 7075 Al Alloy on Microstructures and Mechanical Properties of AZ91 Mg Alloy%7075铝合金对AZ91镁合金组织和性能的影响

      Institute of Scientific and Technical Information of China (English)

      毛萍莉; 杨春海; 张越; 王峰; 刘正

      2013-01-01

      为了研究7075铝合金对AZ91镁合金组织与性能的影响,采用光学显微镜、扫描电镜、X射线衍射仪、万能材料试验机研究了AZ91镁合金的显微组织与力学性能.结果表明:向AZ91镁合金中加入7075铝合金可使该合金的铸态组织明显细化,当7075铝合金含量超过4%(质量分数,下同)时,AZ91镁合金铸态组织中Mg17Al12相数量明显减少,并且组织中生成了A16Mn新相.合金抗拉强度与延伸率随着7075铝合金加入量的增加而提高,当7075铝合金的加入达到4%,其抗拉强度与延伸率达到最大值,分别为186 MPa和8.2%.

    9. AZ31-1Sm镁合金高温压缩热变形行为和微观组织研究%Hot Deformation Behavior and Microstructure of AZ31-1Sm Alloy Compression at Elevated Temperatures

      Institute of Scientific and Technical Information of China (English)

      徐静; 李朝兴; 郑开宏; 黄正华

      2014-01-01

      在单向压缩热模拟试验机上对AZ31-1Sm合金在变形温度为300~450℃、应变速率为0.01~1 s-1条件下的热变形行为和微观组织进行研究.结果表明:AZ31-1Sm镁合金在热压缩变形时,流变应力随着应变速率的增大和变形温度的降低而增大;该合金的热压缩流变应力行为可用双曲正弦形式的本构方程来描述,在本实验条件下,AZ31-1Sm镁合金热热变形激活能Q为160.8 kJ/mol.AZ31-1Sm易发生动态再结晶,在高变形温度和低应变速率条件下动态再结晶趋势明显,动态再结晶晶粒尺寸随着变形温度的增加和应变速率的降低而增大.

    10. Research on Process Parameters of AZ31 Magnesium Alloy Profile Expanding Extrusion%AZ31镁合金型材宽展挤压工艺参数研究

      Institute of Scientific and Technical Information of China (English)

      王锐

      2012-01-01

      在某镁业有限公司的挤压车间进行了AZ31镁合金型材宽展挤压温度、挤压速度和变形程度等工艺参数的研究,在某铝业有限公司进行了AZ31镁合金型材宽展挤压.通过对挤压温度、挤压速度和变形程度进行控制,有效地提高了出品速度和成品率,对于镁合金型材宽展挤压技术具有实践意义.%Extruding process parameters of AZ31 magnesium alloy profile expanding width were researched at a magnesium co., ltd., such as extrusion temperature, extrusion speed, deformation degree, etc., and AZ31 magnesium alloy profile expanding extrusion were implemented at as aluminium w,, ltd. Producing speed and finished product ratio were effectively elevated by effective control of extrusion temperature, extrusion speed and deformation degree. The research has practical significance for magnesium alloy profile expanding extrusion.

    11. 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.)

    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. Effect of β-TCP coating on degradation of AZ31B magnesium alloy%β-TCP涂层对AZ31B镁合金降解的影响

      Institute of Scientific and Technical Information of China (English)

      钟丽芳; 李洪洋; 王秋旭; 艾红军

      2012-01-01

      Objective To investigate the feasibility of AZ31B magnesium alloy coated with β-tricalcium phosphate (β-TCP) as biodegradable bone scaffold material. Methods The AZ31B magnesium alloy uncoated (group A) and coated with β-TCP(group B) were immersed in DMEM culture medium, respectively. The changes of pH valules in the medium and superficial morphology of materials were evaluated after immersion. Results Compared with pre-immersion,on the 3rd day after immersion, the pH. Value was increased in group A(P<0. 05), but was not obviously changed in group B. On the 7th day after immersion, the surface presented crack-like appearance in group A, while the bulk crystal was gradually spheroidized and part of the crystal was dissolved into globus structure in group B. Conclusion Coated with β-TCP can control the early biodegradation of AZ31B magnesium alloy,which is a satisfactory bone scaffold material.%目的 探讨采用β-磷酸三钙(β-TCP)涂层的AZ31B镁合金作为可降解骨支架材料的可行性.方法将无涂层(A组)及β-TCP涂层(B组)AZ31B镁合金浸泡于骨细胞培养基DMEM溶液中,观察模拟体液pH值变化及材料表面形貌的改变.结果 与浸泡前相比,A组浸泡3d时pH值升高(P<0.05),而B组无明显变化.浸泡7d后,A组表面呈龟裂状,而B组表面块状晶体逐渐发生球化,部分晶体有溶解迹象呈团状.结论 β-TCP涂层能控制AZ31B镁合金初期降解速度,β-TCP涂层AZ31B镁合金是一种良好的可降解骨支架材料.

    14. Effects of Solution Treatment on Microstructure and Mechanical Properties of AZ31 Magnesium Alloy at Elevated Temperature%固溶处理对AZ31合金组织与高温力学性能的影响

      Institute of Scientific and Technical Information of China (English)

      王敏; 张敏刚; 孙述利; 孙钢; 柴跃生

      2012-01-01

      Influences of solution treatment on microstructure and mechanical properties of AZ31 magnesium alloy were investigated by Zeiss microscope and X-ray diffraction. The results show that the tensile strength of AZ31 magnesium alloy is increased from 69. 7 Mpa to 86. 6 Mpa with solid solution treatment at 688K from 6 h to 12 h. The β-Mg17 Al12 phase in the microstructure of the AZ31 magnesium is gradually dissolved into the matrix phase after solid solution at 688 K for 12 h. With increasing in the solution time, the static recrystallization in the magnesium alloy can be fully undergone, and a large a-mount of fine recrystallization grains with the average size of 10 μm are generated at the boundary of the AZ31 magnesium alloy after the solid solution at 688 K for 12 h.%采用Zeiss金相显微镜、XRD射线衍射仪研究了不同固溶处理条件对AZ31镁合金的组织及性能的影响.结果表明,AZ31合金的抗拉强度随着固溶时间的延长得到明显提高(由688 K固溶处理6h的69.7 MPa升至12 h的86.6MPa);经过688 K×12h固溶处理的AZ31合金组织中的β-Mg17Al12相逐渐溶解,最后完全溶入基体中;固溶时间的延长保证了再结晶过程的充分进行,688 K固溶处理12h的合金组织晶界处产生了大量平均尺寸为10 μm的细小再结晶晶粒.

    15. Hot Deformation Behavior and Processing Maps of AZ31 Magnesium Alloy%AZ31镁合金的热变形行为及加工图

      Institute of Scientific and Technical Information of China (English)

      肖梅; 周正; 黄光杰; 汪炳叔

      2010-01-01

      用Gleeble-1500D型热模拟试验机对AZ31镁合金在变形温度为473~723 K,应变速率为0.001~1 s-1下的热变形行为进行了试验研究;用双曲正弦关系式描述了该合金在热变形过程中的稳态流变应力;根据合金动态模型,计算并分析了该合金的加工图.结果表明:利用加工图可确定出该合金热变形的流变失稳区,并且得到试验条件下热变形的最佳工艺参数,即变形温度为473~523 K,应变速率为0.01 s-1左右;当变形温度为623~673 K、应变速率为0.001~0.006 s-1时可进行超塑性加工;当变形温度高于673 K后可在较宽的应变速率范围进行热加工.

    16. AZ91镁合金的SIMA法半固态组织特征%Microstructural characteristics of semisolid AZ91 magnesium alloy based on SIMA process

      Institute of Scientific and Technical Information of China (English)

      翟秋亚; 袁森; 蒋百灵

      2005-01-01

      研究了挤压态AZ91镁合金的SIMA法半固态组织演变.结果表明:挤压合金为以α-Mg再结晶等轴晶为主相,与极少量细粒状成串分布于α-Mg基体上的Mg17Al12颗粒组成的两相组织,基体中存在大量的大角度亚晶及高密度的位错缠结.在二次加热过程中,原子扩散通道多,晶界液化及颗粒球化所需的加热温度低,等温时间短.565℃等温5min,即可获得固相率为57%,颗粒平均直径为58 μm、形状圆整、分布均匀的半固态组织.等温5 min后,半固态颗粒发生长大,其长大机制为Ostwald熟化.

    17. Thermodynamic modeling of the Ba - Mg binary system

      Energy Technology Data Exchange (ETDEWEB)

      Ren, Xin; Li, Changrong; Du, Zhenmin; Guo, Cuiping; Chen, Sicheng [Univ. of Science and Technology, Beijing (China). School of Materials Science and Engineering

      2013-04-15

      On the basis of the thermochemical and phase equilibrium experimental data, the phase diagram of the Ba - Mg binary system has been assessed by means of the calculation of phase diagrams technique. The liquid phase is of unlimited solubility and modeled as a solution phase using the Redlich-Kister equation. The intermetallic compounds, Mg{sub 17}Ba{sub 2}, Mg{sub 23}Ba{sub 6} and Mg{sub 2}Ba, with no solubility ranges are treated as strict stoichiometric compounds with the formula Mg{sub m} Ba{sub n}. Two terminal phases, BccBa and HcpMg, are kept as solution phases, since the solubilities of the two phases are of considerable importance. After optimization, a set of self-consistent thermodynamic parameters has been obtained. The calculated values agree well with the available experimental data.

    18. AZ31镁合金高温变形行为及本构模型%Deformation Behavior and Constitutive Equation of AZ31 Magnesium Alloy at Elevated Temperature

      Institute of Scientific and Technical Information of China (English)

      卢雅琳; 李兴成; 李小平; 朱福先

      2011-01-01

      Using Gleeble-3500 thermo-mechanical simulator, hot compression test for AZ31 magnesium alloy at deformation temperatures of 523~723 K and strain rates of 0.01 ~ 10.00 s-1 were carried out under maximum strain of 60%.The experimental results show that flow stress increases apparently with strain.Above a critical peak value, flow stress decreases gradually to be a steady state.The characteristic with the dynamic recrystallization occurs during hot compression of AZ31 magnesium alloy.The effects of deformation temperature and strain rate on flow stress are dominating.In this paper, a constitutive equation with Arrheniues item is established to describe the deformation behavior of AZ31 magnesium alloy at elevated temperature.%采用Gleeble-3500热模拟实验机,对AZ31镁合金在变形温度为523~723 K、应变速率为0.01~10.00 s-1、最大变形程度为60%的条件下进行热压缩实验.结果表明,流变应力随应变的增加而显著增大,到达峰值后逐渐降低并趋于稳态,变形呈明显的动态再结晶特征.变形温度和应变速率对流变应力影响显著,本文采用包含Arrheniues项的本构方程来描述AZ31镁合金的高温变形行为.

    19. Effect of Fluoride Conversion Treatment on Bio-Corrosion Behavior of AZ31B Magnesium Alloy%氟处理对AZ31B镁合金生物耐蚀降解行为的影响

      Institute of Scientific and Technical Information of China (English)

      李绮; 刘新杰; 颜廷亭; 谭丽丽; 张炳春; 杨柯

      2011-01-01

      采用低温化学方法在AZ31B镁合金表面制备出氟涂层,并研究了涂层的表面特征,氟处理后AZ31B镁合金在模拟体液中的腐蚀行为.结果表明,氟涂层均匀致密,与基体结合良好.经氟处理后的AZ31B镁合金的耐蚀性能有较大提高,其在模拟体液中的降解缓慢,合金浸泡后溶液的pH值保持在7.5~8.8之间,有效降低了合金降解而引起的碱性增强趋势.氟涂层在模拟体液中会逐渐转化为Ca3(PO4)2,新生成的表面膜会继续起到保护合金基体的作用.%Fluoride-coating was prepared on AZ31B magnesium alloy by an immersion treatment in hydrofluoric acid at room temperature, and the surface morphology, composition, corrosion resistance and degradation mechanism of the coated alloy were studied. The results show that the conversion coating is compact with good bonding to the alloy. The corrosion resistance of the fluoride coated AZ31B alloy is obviously improved, and its degradation in simulated body fluid (SBF) is slow. The pH value of the SBF (the coated alloy immersed in) keeps in a range of 7.5 to 8.8, which can effectively reduce the alkalization caused by the biodegradation of the alloy. The fluoride coating gradually transform into Ca3(PO4)2 in SBF, which will continue protect the alloy from the corrosion.

    20. 激光重熔处理对AZ31镁合金表面特性的影响%Effects of Laser Cladding Treatment on Surface Performance of AZ31 Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      卫中山; 刘六法

      2011-01-01

      Effects of laser cladding treatment on surface performance of AZ31 magnesium alloy sheet were observed by the help of Nd-YAG laser. Rapid melting-solidification occurs on the surface of the AZ31 magnesium alloy sheet, and treated surface is composed of re-melting zone and heat history zone.Grain size is apparently refined in the re-melting zone, and hardness is increased by 5 % compared to that of the matrix. Immersing corrosion experiment shows that corrosion resistance of AZ31 magnesium alloy with laser cladding treatment is greatly improved in 3.5 % NaC1 solution, which is attributed to grain refinement in re-melting zone and enrichment of Al element in cladding surface.%使用Nd-YAG激光器对AZ31镁合金板材表面进行了激光重熔处理,分析了激光重熔处理对其表面特性的影响.在激光扫描时,试样表面发生了快速熔凝,处理层可分为重熔区、热影响区两部分.重熔区的晶粒得到明显细化,硬度比基体提高5%.腐蚀试验表明,AZ31镁合金在激光重熔处理后,在3.5%的NaCl溶液中的耐蚀性得到明显改善.重熔区晶粒细化和Al元素富集是激光重熔表面处理提高其耐蚀性的主要因素.

    1. Warm Deep Drawing of Rectangular Parts of AZ31 Magnesium Alloy Sheet Adopting Variable Blank Holder Force

      Science.gov (United States)

      Ying-hong, Peng; Qun-feng, Chang; Da-yong, Li; Xiao-qin, Zeng

      2007-05-01

      AZ31 magnesium alloy sheet with good shape and formability is fabricated by warm cross rolling. Uniaxial tensile tests are conducted using a Gleeble 3500 thermal - mechanical simulator, and the mechanical properties of AZ31 magnesium alloy sheet are analyzed. A warm deep drawing process of square part is also simulated by the finite element method. The influences of blank holder force on the formability are numerically investigated. A double-action hydraulic press that can realize adjustable blank holder forces is developed and its working principle and control system are introduced. Some warm deep drawing experiments of square parts of AZ31 magnesium alloy sheet are also performed. Different variation schemes of the blank holder force with the stroke of the punch are tested, and the experiment results are compared. Results show that the suitable blank holder force variation scheme is a ladder curve with the punch stroke. Adopting the variable blank holder force technique can improve 13.2% of the drawing depth of square parts of AZ31 magnesium alloy sheet.

    2. Pump Jet Mixing and Pipeline Transfer Assessment for High-Activity Radioactive Wastes in Hanford Tank 241-AZ-102

      Energy Technology Data Exchange (ETDEWEB)

      Y Onishi; KP Recknagle; BE Wells

      2000-08-09

      The authors evaluated how well two 300-hp mixer pumps would mix solid and liquid radioactive wastes stored in Hanford double-shell Tank 241-AZ-102 (AZ-102) and confirmed the adequacy of a three-inch (7.6-cm) pipeline system to transfer the resulting mixed waste slurry to the AP Tank Farm and a planned waste treatment (vitrification) plant on the Hanford Site. Tank AZ-102 contains 854,000 gallons (3,230 m{sup 3}) of supernatant liquid and 95,000 gallons (360 m{sup 3}) of sludge made up of aging waste (or neutralized current acid waste). The study comprises three assessments: waste chemistry, pump jet mixing, and pipeline transfer. The waste chemical modeling assessment indicates that the sludge, consisting of the solids and interstitial solution, and the supernatant liquid are basically in an equilibrium condition. Thus, pump jet mixing would not cause much solids precipitation and dissolution, only 1.5% or less of the total AZ-102 sludge. The pump jet mixing modeling indicates that two 300-hp mixer pumps would mobilize up to about 23 ft (7.0 m) of the sludge nearest the pump but would not erode the waste within seven inches (0.18 m) of the tank bottom. This results in about half of the sludge being uniformly mixed in the tank and the other half being unmixed (not eroded) at the tank bottom.

    3. High Cycle Fatigue Properties of Die-Cast Magnesium Alloy AZ91D with Addition of Different Concentrations of Cerium

      Institute of Scientific and Technical Information of China (English)

      2006-01-01

      The effect of addition of different concentrations of Ce on high-cycle fatigue behavior of die-cast magnesium al-loy AZ91D was investigated. Mechanical fatigue tests were conducted at the stress ratio of R = 0.1, and fatigue strength was evaluated using up-and-down loading method. The results show that the grain size of AZ91D alloy is remarkably refined, and the amount of porosity decreases and evenly distributes with the addition of Ce. The fatigue strength of AZ91D alloy at room temperature increases from 96.7 up to 116.3 MPa (1% Ce) and 105.5 MPa (2% Ce), respectively, at the number of cycles to failure, Nf = 1 × 107. The fatigue crack of AZ91D alloy initiates at porosities and inclusions, and propagates along grain boundaries. The fatigue striations on fractured surface appear with Ce addition. The fatigue fracture surface of test specimens shows mixed-fracture characteristics of quasi-cleavage and dimple.

    4. 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...

    5. 76 FR 70957 - Foreign-Trade Zone 277-Western Maricopa County, AZ; Application for Manufacturing Authority, Sub...

      Science.gov (United States)

      2011-11-16

      ... Manufacturing Authority, Sub-Zero, Inc. (Refrigerators and Freezers), Goodyear, AZ An application has been..., Inc., grantee of FTZ 277, requesting manufacturing authority on behalf of Sub-Zero, Inc. (Sub-Zero... was formally filed on November 10, 2011. The Sub-Zero facility (260 employees, 10 acres, 150,000...

    6. 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.

    7. 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... Guard is establishing a temporary safety zone within the navigable waters of Thompson Bay in Lake Havasu... Thompson Bay, Lake Havasu, AZ for The Lucas Oil Drag Boat Racing Series. This safety zone is necessary...

    8. 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.

    9. Processing and mechanical properties of SiC particulate reinforced AZ91 composites fabricated by stir casting

      Institute of Scientific and Technical Information of China (English)

      WANG Xiao-jun; WU Kun; PENG De-lin; ZHANG Hai-feng; ZHENG Ming-yi; HUANG Wen-xian

      2006-01-01

      The influence of stirring parameters (stirring temperature, stirring speed and stirring time) on the particle distribution of 10%(volume fraction) SiC particulate reinforced AZ91 composites (SiCp/AZ91) was studied. It is found that it is necessary for 10 μm SiC particulate reinforced AZ91 composites to stir the molten composites in semi-solid condition with vortex formation, or else the cluster of the reinforcements would not be eliminated. Compared with the monolithic alloy, the SiCp/AZ91 composite has higher strength, especially for yield strength, but the elongation is reduced. For the as-cast composite, the particles often segregate within the grain boundary regions. Extrusion can effectively reduce the segregation of SiC particles and improve the mechanical properties of the composite. The extrusion-induced reduction in particle size varies with extrusion temperatures and extrusion ratios. The effect of extrusion-induced reduction in particle size on the mechanical properties of the composites is not always beneficial.

    10. Effect of combinative addition of strontium and rare earth elements on corrosion resistance of AZ91D magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      NIU Jie-xin; CHEN Qiu-rong; XU Nai-xin; WEI Zhong-ling

      2008-01-01

      The influence of strontium(Sr) and rare earth(RE) elements on the corrosion behavior of AZ91D magnesium alloy was investigated by conventional corrosion testing and electrochemical measurements in 3.5% NaCI solution. After comparing the mass loss and hydrogen evolution of the samples, the microstruetures of the alloys and the morphologies of their corrosion product films were characterized by electron probe microanalysis-energy dispersive spectrometry(EPMA-EDS) and Auger electron spectroscopy(AES). Compared with individual addition of Sr or RE to AZ91D, the combinative addition of 0.5% Sr and 1% RE to AZ91D successfully decreases the corrosion rate further, which can be attributed to the depression of micro-galvanic couples, as well as the formation of more protective film due to aluminum enrichment. The combinative addition of strontium and rare earth elements to AZ91D magnesium alloy appears to he a promising approach to increase its corrosion resistance.

    11. The redshift and nature of AzTEC/COSMOS 1: A starburst galaxy at z=4.6

      CERN Document Server

      Smolcic, V; Ilbert, O; Blain, A W; Salvato, M; Aretxaga, I; Schinnerer, E; Masters, D; Moric, I; Riechers, D A; Sheth, K; Aravena, M; Aussel, H; Aguirre, J; Berta, S; Carilli, C L; Civano, F; Fazio, G; Huang, J; Hughes, D; Kartaltepe, J; Koekemoer, A M; Kneib, J -P; LeFloc'h, E; Lutz, D; McCracken, H; Mobasher, B; Murphy, E; Pozzi, F; Riguccini, L; Sanders, D B; Sargent, M; Scott, K S; Scoville, N Z; Taniguchi, Y; Thompson, D; Willott, C; Wilson, G; Yun, M

      2011-01-01

      Based on broad/narrow-band photometry and Keck DEIMOS spectroscopy we report a redshift of z=4.64-0.08+0.06 for AzTEC/COSMOS 1, the brightest sub-mm galaxy in the AzTEC/COSMOS field. In addition to the COSMOS-survey X-ray to radio data, we report observations of the source with Herschel/PACS (100, 160 micron), CSO/SHARC II (350 micron), CARMA and PdBI (3 mm). We do not detect CO(5-4) line emission in the covered redshift ranges, 4.56-4.76 (PdBI/CARMA) and 4.94-5.02 (CARMA). If the line is within this bandwidth, this sets 3sigma upper limits on the gas mass to <~8x10^9 M_Sol and <~5x10^10 M_Sol, respectively (assuming similar conditions as observed in z~2 SMGs). This could be explained by a low CO-excitation in the source. Our analysis of the UV-IR spectral energy distribution of AzTEC 1 shows that it is an extremely young (<~50 Myr), massive (M*~10^11 M_Sol), but compact (<~2 kpc) galaxy forming stars at a rate of ~1300 M_Sol/yr. Our results imply that AzTEC 1 is forming stars in a 'gravitationall...

    12. Software para el análisis de producciones integradas de azúcar y alcohol (SANPAD 5.0

      Directory of Open Access Journals (Sweden)

      Rafael Hurtado-Vargas

      2012-01-01

      Full Text Available La producción de etanol a partir de jugo de caña y mieles finales es una alternativa muy común en la industria azucarera actual. En una producción integrada donde se produce azúcar y alcohol, deben considerarse varias alternativas de producción en dependencia del comportamiento del mercado. Por tal motivo, una herramienta de software para la toma de decisiones es muy útil para seleccionar una, entre varias estrategias de producción. Para desarrollar el software SANPAD®, las alternativas más comunes en la producción integrada de azúcar y alcohol fueron tomadas en cuenta. Incluye el análisis de diferentes composiciones de materias primas para la destilería (uso de jugo de filtros, mieles, jugo primario, etc. y sus pasos de purificación. Fueron estudiadas además, e incluidas en el software, diferentes estrategias para producir azúcar crudo y refino. El modelo matemático concibe todas estas posibilidades en los balances de masa y energía en las fábricas. El resultado es un software útil que puede ser usado para el análisis de alternativas en la producción integrada de azúcar y alcohol. El software es descrito a través de un caso de estudio para mostrar sus posibilidades.

    13. DongBa Dance--Mixture of cultures

      Institute of Scientific and Technical Information of China (English)

      赵春娟

      2014-01-01

      DongBa Dance is a kind of ancient dance that created by Naxi people living in the Southwest of China and recorded by their own hieroglyph.During the development, it adopted parts of Tibetan, Indian and Egyptian cultures.So, as the mixture of cultures, DongBa Dance is marching into the world and causing a great attention.The ancient DongBa Dance will get a new life in the world.

    14. DongBa Dance——Mixture of cultures

      Institute of Scientific and Technical Information of China (English)

      赵春娟

      2014-01-01

      Dong Ba Dance is a kind of ancient dance that created by Naxi people living in the Southwest of China and recorded by their own hieroglyph.During the development, it adopted parts of Tibetan, Indian and Egyptian cultures.So, as the mixture of cultures, Dong Ba Dance is marching into the world and causing a great attention.The ancient Dong Ba Dance will get a new life in the world.

    15. 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

    16. Microstructure, mechanical properties and texture evolution of AZ31 alloy containing trace levels of strontium

      Energy Technology Data Exchange (ETDEWEB)

      Sadeghi, Alireza, E-mail: alireza.sadeghi@mail.mcgill.ca; Pekguleryuz, Mihriban

      2011-08-15

      The effect of low levels of Sr (0.01, 0.03, 0.05 wt.%) on the microstructure, mechanical properties and texture of AZ31 magnesium alloy has been investigated. Thermodynamic modeling has been used to study the effect of Sr on phase precipitation at different temperatures. Cooling curve analysis reveals a decrease in solidification superheat with the addition of 0.03 wt.% Sr to AZ31. The as-cast microstructures of the alloys have been studied using optical microscopy (OM) and electron probe micro analysis (EPMA). Results show the refining effect of Sr on the grain size and on the {beta}-Mg{sub 17}Al{sub 12} precipitates through growth poisoning and inoculation, respectively. To investigate the mechanical properties of the alloys, as-cast samples were compression tested at elevated temperatures. Hot compression peak stress ({sigma}{sub max}) and critical strain before recrystallization ({epsilon}{sub c}) initially drop but then increase. {sigma}{sub max} first decreases due to the depletion of Al from solid solution and then increases when the amount of the Al-Sr precipitates reach a significant amount. {epsilon}{sub c} drops due to the acceleration of dynamic recrystallization kinetics as a result of grain refinement. It increases with increasing Sr when the concentration Sr in solid solution is increased leading to dislocation pinning and retardation of recrystallization. X-ray texture measurements on the hot compressed and extruded samples show a decrease in maximum intensity of the basal pole figures with increasing Sr as a result of reduced twining and the changes in Al and Sr concentrations in solid solution. - Research Highlights: {yields} Microstructures/precipitates of AZ31+trace levels of Sr were examined by OM and EPMA. {yields} Thermodynamic calculations and cooling curve analysis were used to predict ppt formation. {yields} It has been shown that Sr refines the grains and Mg17Al12 precipitates. {yields} Mechanical properties and texture were studied using

    17. 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

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

      Science.gov (United States)

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

      1988-10-01

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

    19. Preparation of directionally solidified BaTi2O5-Ba6Ti17O40 eutectic by the floating zone method

      Science.gov (United States)

      Shiga, K.; Katsui, H.; Goto, T.

      2017-02-01

      The BaTi2O5-Ba6Ti17O40 eutectic (BaO-68.7 mol% TiO2) was directionally solidified by the floating zone (FZ) method and crystalline phases, microstructures and orientation were investigated. Ba6Ti17O40 with faceted rod-like shape was dispersed in the BaTi2O5 matrix. The growth directions of BaTi2O5 and Ba6Ti17O40 were parallel to the b and a axis, respectively, and the orientation relations were BaTi2O5 (010)//Ba6Ti17O40(60 2 ̅) and BaTi2O5 (001)//Ba6Ti17O40 (001).

    20. Efecto de aplicación de biosólidos sobre las propiedades físicas de un suelo cultivado con caña de azúcar

      Directory of Open Access Journals (Sweden)

      Waldemar Peñarete M

      2013-07-01

      Full Text Available Se evaluó el efecto de la aplicación de biosólidos resultantes de la Planta de Tratamiento de Aguas Residuales (PTAR Cañaveralejo, Cali, Colombia, sobre las propiedades físicas (densidad aparente, porosidad y estabilidad estructural de un suelo Vertic endoaquepts con características vérticas, sembrado con caña de azúcar, así como la influencia sobre el rendimiento del cultivo. Se utilizó un diseño experimental de bloques completos al azar con dos repeticiones y ocho tratamientos: dos testigos (suelo sin biosólido y sin fertilización mineral (To y suelo con fertilización mineral (FM y seis tratamientos con biosólidos aplicando 100% y 200% de la dosis de nitrógeno requerida por el cultivo así: BD100 y BD200 biosólidos deshidratados, BST100 y BST200 biosólidos deshidratados secados térmicamente y BA100 y BA200 biosólidos alcalinizados. Los resultados mostraron cambios ligeros en las propiedades físicas del suelo y en el rendimiento del cultivo. Se observó una tendencia en los tratamientos con biosólidos de disminuir la densidad aparente (de 1.33 Mg m-3 a 1.29 Mg m-3 y la microporosidad (48.8% a 45.8% y de aumentar la estabilidad estructural (1.8 mm a 3.1 mm y la macroporosidad (2.0% a 5.0%.

    1. Transition probabilities in the (5) candidate 122Ba

      CERN Document Server

      Bizzeti, P G; Tonev, D; Giannatiempo, A; Ur, C A; Dewald, A; Melon, B; Michelagnoli, C; Petkov, P; Bazzacco, D; Costin, A; de Angelis, G; Della Vedova, F; Fantuzi, M; Farnea, E; Fransen, C; Gadea, A; Lenzi, S; Lunardi, S; Marginean, N; Marginean, R; Menegazzo, R; Mengoni, D; Moeller, O; Nannini, A; Napoli, D R; Nespolo, M; Pavan, P; Perego, A; Petrache, C M; Pietralla, N; Alvarez, C Rossi; Sona, P

      2010-01-01

      To investigate the possible X(5) character of 122Ba, suggested by the ground state band energy pattern, the lifetimes of the lowest yrast states of 122Ba have been measured, via the Recoil Distance Doppler-Shift method. The relevant levels have been populated by using the 108Cd(16O,2n)122Ba and the Sn(13C,3n)122Ba reactions. The B(E2) values deduced in the present work are compared to the predictions of the X(5) model and to calculations performed in the framework of the IBA-1 and IBA-2 models.

    2. Geoenvironmental weathering/deterioration of landfilled MSWI-BA glass.

      Science.gov (United States)

      Wei, Yunmei; Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki; Zhao, Chun; Peng, Xuya; Gao, Junmin

      2014-08-15

      Municipal solid waste incineration bottom ash (MSWI-BA) glass serves as a matrix of assorted bottom ash (BA) compounds. Deterioration of the BA glass phases is quite important as they regulate the distribution of a series of toxic elements. This paper studied landfilled MSWI-BA samples from the mineralogical and geochemical viewpoint to understand the deterioration behavior of the BA glass phases as well as mechanisms involved. Bulk analysis by PXRD as well as micro-scale analysis by optical microscopy and SEM/EDX was conducted for such purposes. The results revealed that dissolution of the BA glass phases has resulted in a deterioration layer of 10(0)-10(2)μm thickness after years of disposal. This rapid weathering process is highly relevant to the specific glass characteristics and solution pH. The BA glass phases with more embedded compounds and cracks/fissures tend to be more vulnerable. Moreover, the generally alkaline pH in ash deposit favors a rapid disruption of the glass phase. The weathering products are mainly gel phases (including Al-Si gel, Ca-Al-Si gel, Fe-Al-Si gel etc.) with iron oxide/hydroxide as accessory products. Breakdown of the BA glass phases triggers chemical evolution of the embedded compounds. Based on all the findings above, a model is proposed to illustrate a general evolution trend for the landfilled MSWI-BA glass phases.

    3. Solubility of BaS in BaO-BaF2 slag and the Influence of FeOx, SiO2, Cr2O3, BaCI2, CaO, and MgO on the sulfide capacity of this system

      Science.gov (United States)

      Rachev, Ivan P.; Tsukihashi, Fumitaka; Sano, Nobuo

      1992-03-01

      The influence of SiO2, FeOx, Cr2O3, BaCl2, CaO, and MgO on the sulfide capacity of the BaO-BaF2 system was measured at 1473 K, using a gas-slag-metal equilibration technique. It was found that the substitution of BaF2 by SiO2, FeOx, Cr2O3, and BaCl2 decreases the sulfide capacity of the BaO-BaF2 system. Similar results were obtained for the carbonate capacity. The CaO-saturated BaO-BaF2 flux, however, was found to have slightly higher sulfide and carbonate capacities than the pure BaO-BaF2 flux. The solubility of CaO increased with increasing BaF2 content and was 18 mol pet in BaF2 at 1473 K. The solubility of MgO in the BaO-BaF2 system at the same temperature is very low, and it has no effect on the sulfide and carbonate capacities. The solubility of BaS in the BaO-BaF2 system was also measured at 1473 K and had its maximum for the slag containing 40 mass pet BaO. The activity of BaO in the system was calculated from those data.

    4. Um baú de fundo fundo: e esse baú nunca acaba?

      Directory of Open Access Journals (Sweden)

      Luciano Flávio de Oliveira

      2013-10-01

      Full Text Available In this paper I discuss the cultural representations in the text and in the characters of Um baú de fundo fundo, show created in 1974, by the Giramundo Teatro de Bonecos, of Belo Horizonte city. Therefore, I observe the concepts of culture, more specifically cultures in plural, and representation.

    5. A computer simulation study of oxygen defect centers in BaFBr and BaFCl

      Energy Technology Data Exchange (ETDEWEB)

      Islam, M.S.; Baetzold, R.C. (Eastman Kodak Company, Rochester, NY (United States). Corporate Research Labs.)

      1992-01-01

      Atomistic simulation techniques are used to examine several oxygen trapped-hole centers resulting from X-irradiation of BaFBr and BaFCl crystals. The calculations employ recently derived interatomic potentials for the oxide ion-host anion interactions. Particular attention is focussed on the sites occupied by the oxide impurity and the energetics of ionization. Our results show the defect model involving O{sup -} substitutional at a Br{sup -}/Cl{sup -} site to be a favorable trapped-hole center, in accord with the assignment proposed from electron paramagnetic resonance measurements. The defect simulations find a large energy barrier to oxide interstitial formation from the oxide precursor at a substitutional site, which suggests that conversion from O{sub x}{sup -} to O{sub int}{sup -} is highly unlikely as has been demonstrated in EPR experiments. Ion displacements following lattice relaxation about the defect are also examined. The position of O{sup -} substituted for Br{sup -} in BaFBr is computed to be displaced from the regular lattice site by 0.53 A, along the c axis towards the Ba{sup 2+} ion plane, in agreement with models derived later from ENDOR experiments, while O{sup -} substituted for F{sup -} remains on the lattice site in agreement with experiment. (author).

    6. Revisiting the BaO2/BaO redox cycle for solar thermochemical energy storage.

      Science.gov (United States)

      Carrillo, A J; Sastre, D; Serrano, D P; Pizarro, P; Coronado, J M

      2016-03-21

      The barium peroxide-based redox cycle was proposed in the late 1970s as a thermochemical energy storage system. Since then, very little attention has been paid to such redox couples. In this paper, we have revisited the use of reduction-oxidation reactions of the BaO2/BaO system for thermochemical heat storage at high temperatures. Using thermogravimetric analysis, reduction and oxidation reactions were studied in order to find the main limitations associated with each process. Furthermore, the system was evaluated through several charge-discharge stages in order to analyse its possible degradation after repeated cycling. Through differential scanning calorimetry the heat stored and released were also determined. Oxidation reaction, which was found to be slower than reduction, was studied in more detail using isothermal tests. It was observed that the rate-controlling step of BaO oxidation follows zero-order kinetics, although at high temperatures a deviation from Arrhenius behaviour was observed probably due to hindrances to anionic oxygen diffusion caused by the formation of an external layer of BaO2. This redox couple was able to withstand several redox cycles without deactivation, showing reaction conversions close to 100% provided that impurities are previously eliminated through thermal pre-treatment, demonstrating the feasibility of this system for solar thermochemical heat storage.

    7. Effect of microalloying (Ca, Sr, and Ce) on elevated temperature tensile behavior of AZ31 magnesium sheet alloy

      Energy Technology Data Exchange (ETDEWEB)

      Shang, L., E-mail: lihong.shang@mail.mcgill.ca [McGill University, Dept. of Materials Eng., Montreal, QC H3A 2B2 (Canada); Yue, S. [McGill University, Dept. of Materials Eng., Montreal, QC H3A 2B2 (Canada); Verma, R.; Krajewski, P. [General Motors Research and Development Center, Warren, MI 48090 (United States); Galvani, C.; Essadiqi, E. [Natural Resources Canada-CANMET, Ottawa, ON K1A 0G1 (Canada)

      2011-04-25

      Research highlights: {yields} Hot tensile behavior of AZ31 sheet microalloyed with Ca, Sr and Ce was investigated. {yields} Under superplastic conditions the formability is notably improved by microalloying. {yields} Second phase particles resist grain coarsening and retard cavitations' development. {yields} Under the high Z conditions the deformation is controlled by the dislocation creep. {yields} Under the low Z conditions the deformation is controlled by grain boundary sliding. - Abstract: The effect of microalloying with calcium, strontium, and cerium on the microstructure and the elevated temperature deformation behavior of magnesium sheet alloy AZ31 was investigated. Base composition and microalloyed AZ31 materials were cast and rolled into wrought sheet by an identical thermo-mechanical process. A series of hot tensile tests (temperatures of 300 deg. C, 400 deg. C, and 450 deg. C; constant true strain rates of 0.1 s{sup -1}, 0.01 s{sup -1}, 0.001 s{sup -1}, and 0.0003 s{sup -1}) were performed to characterize the deformation behavior of the sheet alloys. Interrupted tensile tests were used to study microstructural evolution with strain. A well-dispersed and thermally stable second phase produced by microalloying refines, stabilizes the grain structure, and significantly enhances hot formability of AZ31 sheet. The enhancement is most pronounced under deformation conditions of 450 deg. C and; 0.0003 s{sup -1} strain rate, with tensile elongation increasing from 347% for the base alloy, to 406% with Ca only, 437% with Ca and Ce, and 552% with Ca, Sr and Ce for microalloyed AZ31 alloys. The second phase particles resist grain coarsening, promote grain boundary sliding, retard strain localization or necking, and postpone cavitation to higher strain levels to achieve this improvement in formability.

    8. Processing Technology and Mechanical Properties of Die-Cast Magnesium Alloy AZ91D

      Institute of Scientific and Technical Information of China (English)

      LIU Yan'gai(刘艳改); LIU Wenhui(刘文辉); XIONG Shoumei(熊守美); LIU Baicheng(柳百成); Wang Gang (王罡); MATSUMOTO Yoshihide; MURAKAMI Masayuki

      2004-01-01

      The mechanical properties of magnesium die-casting components can be improved with improved die-casting processing technology. An orthogonal experiment with four factors and three levels (Lq, 34) was used to evaluate the effect of various die-casting processing parameters on the quality and mechanical properties of an AZ91D magnesium alloy cylinder head cover component. The results show that the injection speed and casting and die temperatures all influence the component quality, with the influence of the casting pressure being the smallest. The injection speed and casting pressure are the two most important factors influencing the tensile strength. The best die-casting parameters for the magnesium alloy cylinder head cover component were determined to be a casting temperature of 660℃, a die temperature of 200℃, an injection speed of 70 ms(1, and a casting pressure of 65 MPa. The porosity is one of the most important parameters influencing the casting strength.

    9. Evaluation of cracking in the 241-AZ tank farm ventilation line at the Hanford Site

      Energy Technology Data Exchange (ETDEWEB)

      ANANTATMULA, R.P.

      1999-10-20

      In the period from April to October of 1988, a series of welding operations on the outside of the AZ Tank Farm ventilation line piping at the Hanford Site produced unexpected and repeated cracking of the austenitic stainless steel base metal and of a seam weld in the pipe. The ventilation line is fabricated from type 304L stainless steel pipe of 24 inch diameter and 0.25 inch wall thickness. The pipe was wrapped in polyethylene bubble wrap and buried approximately 12 feet below grade. Except for the time period between 1980 and 1987, impressed current cathodic protection has been applied to the pipe since its installation in 1974. The paper describes the history of the cracking of the pipe, the probable cracking mechanisms, and the recommended future action for repair/replacement of the pipe.

    10. Semiconducting behavior of the anodically passive films formed on AZ31B alloy

      Directory of Open Access Journals (Sweden)

      A. Fattah-alhosseini

      2014-12-01

      Full Text Available This work includes determination of the semiconductor character and estimation of the dopant levels in the passive film formed on AZ31B alloy in 0.01 M NaOH, as well as the estimation of the passive film thickness as a function of the film formation potential. Mott–Schottky analysis revealed that the passive films displayed n-type semiconductive characteristics, where the oxygen vacancies and interstitials preponderated. Based on the Mott–Schottky analysis, it was shown that the calculated donor density increases linearly with increasing the formation potential. Also, the electrochemical impedance spectroscopy (EIS results indicated that the thickness of the passive film was decreased linearly with increasing the formation potential. The results showed that decreasing the formation potential offer better conditions for forming the passive films with higher protection behavior, due to the growth of a much thicker and less defective films.

    11. Finite element simulation on press forging of magnesium alloy AZ31 sheets

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      Press forging of rectangular box of magnesium alloy AZ31 sheets was investigated at elevated temperatures.The characteristics of metal flow were analyzed on the basis of finite element method(FEM)and experiments.Effects of friction factor and sidewall thickness on metal flow and boss forming were investigated by FEM.The results indicate that the bosses and the sidewall of the rectangular box are formed unevenly due to the uneven flow of the metal.The increase in friction factor at die/sheet interface improves the metal flow pattem and the efficiency of boss forming,but reduces the sidewall uniformity.Decrease in sidewall thickness enhances boss forming efficiency,whereas the punch load increases in this case.The present work can provide rcasonable parameters and design guideline for the practical press foxing process of magnesium alloy sheets.

    12. Porfirio Díaz en la historiografía masónica mexicana

      OpenAIRE

      Marco Antonio Flores Zavala

      2015-01-01

      En este artículo se analiza la presencia del general Porfirio Díaz en la historiografía masónica mexicana. Para la redacción de este texto se recurrió a las obras de José María Mateos (Historia de la masonería en México desde 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 es básico: ¿Qué fuentes documentales utilizaron los autores para red...

    13. Microstructure and texture evolution of AZ31 magnesium alloy during rolling

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      The production of magnesium alloy sheets normally involves several processing stages including hot rolling, cold rolling and intermediate annealing. The microstructure and texture evolution of AZ31 magnesium alloy sheets in different processing states were investigated by optical microscopy and X-ray diffraction technique. It is found that the microstructure of hot-rolled sheets is dominated by recrystallized equiaxed grains, while that of cold-rolled sheets is dominated by deformation twins. With final annealing applied on the cold-rolled sheets, fine recrystallization grains are obtained and ductility of the samples is increased. It is also found that the texture of magnesium alloy sheets prefers the basal texture, and other compositions of texture are relatively weak. Moreover,final annealing does not significantly affect texture distribution. The results of this study provide useful guidelines for optimizing the processing of magnesium alloys.

    14. Mechanical properties and texture evolution during hot rolling ofAZ31 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      SUN Hong-fei; LIANG Shu-jin; WANG Er-de

      2009-01-01

      Mechanical properties and texture evolutions of the as-rolled AZ31 Mg sheets were investigated. The results show that the grains of the sheets are significantly refined after hot rolling. The mechanical properties of the as-rolled samples are enhanced due to the grain size refinement. The intensity of basal texture decreases with the increase of deformation ratio, and double-peak type basal texture is discovered in the intermediate and large strain hot rolling processes. The formation of the texture is ascribed to the activities of prismatic and non-basal slips, which is the same as the 30% rolled and 50% rolled samples. The incline of basal planes exerts an effect on the mechanical anisotropy during tension along rolling direction (RD) and transverse direction (TD) at room temperature.

    15. Warm deformation behavior of hot-rolled AZ31 Mg alloy

      Energy Technology Data Exchange (ETDEWEB)

      Yin, D.L. [Key Laboratory of Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China)]. E-mail: d_l_yin2000@hit.edu.cn; Zhang, K.F. [Key Laboratory of Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); Wang, G.F. [Key Laboratory of Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); Han, W.B. [Key Laboratory of Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China)

      2005-02-15

      Uniaxial tensile test was employed to evaluate the warm deformation properties of hot-rolled AZ31 Mg alloy at a temperature range of 50-200 deg. C and a strain rate range of 1.4 x 10{sup -3} s{sup -1}-1.4 x 10{sup -1} s{sup -1}. The dynamic recrystallization (DRX) and twinning during the warm deformation were observed by optical microscopy (OM) and transmission electronic microscopy (TEM). It is shown that twinning characterized by a compound mode with differently oriented twins intersecting each other is the dominant deformation mechanism at low temperatures and initial deformation stage. The distortion energy accumulated by twinning is the reason for the occurrence of DRX.

    16. Application of Anand's constitutive model on twin roll casting process of AZ31 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      HU Xiao-dong; JU Dong-ying

      2006-01-01

      Twin-roll thin strip casting process combines casting and hot rolling into a single process,in which thermal stress and thermal mechanical stress were involved. Considering the high temperature gradient,the existing of liquid and solid regions and rolling deformation,suitable constitutive model is the key to describe the process. Anand's model is a temperature-dependent,rate-dependent and unified of creep and plasticity model and the Jaumann derivative was employed in Anand's model which makes the constitutive model frame-indifferent or objective,therefore the highly nonlinearities behavior in the twin-roll casting process can be simulated. The parameters of the Anand's model were regressed based on the compression tests of AZ31 magnesium alloy. The simulation results reveal that the Anand's model can well describe the deformation characteristics of twin-roll casting process. Based on the simulation results,the form of evolution equations in Anand's model was discussed.

    17. Hot-deformation behaviors of AZ31 alloys with different initial states

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      The hot-deformation behaviors of three types of AZ31 samples, extruded sheet, hot rolled sheet and east rod were studied.These samples had different initial grain size and texture. Compression deformation of these samples was carried out using a Gleeble 1500D under a series of thermal deformation conditions. Mierostructure and texture of the initial and deformed samples were examined using electron backscatter diffraction (EBSD) techniques. The flow curves for all these three types of samples shifted upward with strain rate increasing. Significant grain refinement was noticed in the hot rolled sheet sample. The grain size was reduced to 3.7 μm after 50% (ε=0.69) compression. The DRX grains in both the extruded rod and hot rolled sheet samples presented the same basal plane texture, irrespective of the difference in the initial texture of the samples.

    18. Microstructural evolution during hot rolling of an AZ31 Mg alloy

      Energy Technology Data Exchange (ETDEWEB)

      Valle, J.A. del; Perez-Prado, M.T.; Ruano, O.A. [Dept. of Physical Metallurgy, Centro Nacional de Investigaciones Metalurgicas (CENIM), CSIC, Madrid (Spain)

      2003-07-01

      The microstructural evolution of a AZ31 Mg alloy during hot rolling has been investigated using optical microscopy and texture (macro and micro) analysis as the main characterization tools. In particular, the differences between the microstructure obtained by unidirectional rolling (UR) and cross rolling (CR) are studied. Significant twinning activity is observed in both cases. Additionally, after cross rolling, a rather heterogeneous microstructure develops, with scattered regions populated by very fine grains. The strong basal fiber texture of the as-received material remains present after both hot rolling schemes. The impossibility to obtain accurate EBSD measurements within the twinned regions suggests that significant localized deformation takes place in those areas. Thus, these regions become preferential sites for the onset of recrystallization due to the increase in the local strain energy. (orig.)

    19. Influence of initial textures on dynamic recrystallization and textures in AZ31 magnesium alloys

      Institute of Scientific and Technical Information of China (English)

      YANG Ping(杨平); CUI Feng-e(崔凤娥); MA Shi-cai(马世才); G Gottstein

      2003-01-01

      Microscopy and X-ray diffractometry were applied to inspect the influence of initial texture on dynamic recrystallization and texture formation in AZ31 magnesium alloys during channel die compression. The results show that stress-strain curves, microstructures and textures depend on initial textures. Two types of nucleation sites are detected which are in different proportions depending on initial textures. Dynamic recrystallization proceeds faster in samples with more inhomogeneity. When the basal planes of grains are parallel to rolling plane of sample with scattering around transverse direction, no new texture component occurs and texture is strengthened together with dynamic recrystallization. By other initial textures there are texture changes during hot deformation. New grains rotate gradually to basal orientation at heavy strain.

    20. Effect of cerium and lanthanum additives on plasma electrolytic oxidation of AZ31 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      沈德久; 马豪杰; 郭长虹; 蔡景瑞; 李国龙; 何东磊; 杨庆祥

      2013-01-01

      Plasma electrolytic oxidation (PEO) coatings on AZ31 magnesium (Mg) alloy were developed using the aqueous solution with alkaline silicate and sodium hydroxide as a base electrolyte system. The effects of cerium (Ce) nitrate and lanthanum (La) nitrate additives on the voltage response, microstructure, compositions and corrosion resistance of PEO coatings were investigated by scan-ning electron microscopy (SEM), energy-dispersive spectrum (EDS), X-ray diffraction (XRD) and potentiodynamic polarization tests, etc. The results showed that Ce and La additives increased the stable voltage and compactness of the PEO coatings, while, those did not change the compositions of the PEO coatings. The corrosion resistance of the PEO coating obtained in solutions with La nitrate of 0.1 g/L was the best, followed by that with Ce nitrate of 0.1 g/L and that without additives.

    1. Corner forming of AZ61A magnesium alloy tube within warm hydroforming

      Institute of Scientific and Technical Information of China (English)

      HU Lan; HAN Cong; HE Zhu-bin; TANG Ze-jun; LIU Gang; YUAN Shi-jian

      2009-01-01

      The corners with small radii on cross sections are crucial for forming hydroformed components with polygonal sections. In this paper, warm hydroforming experiments of AZ61 A magnesium alloy tubes were carried out to study the forming regularity of round corners by using a demonstration part with square sections.Effects of temperature on radius forming, thinning ratio distribution and microstructure were revealed and a component with relative outer corner radius of 3.0 was obtained by warm hydroforming at 240℃. The minimum thickness of the formed square section was located in the transition position between the corner and the straight wall. The thinning ratio of the round corner increased with the increase of forming temperature. Formability of the magnesium tube was improved by raising temperature under the effect of dynamic recrystallization at 240℃.

    2. Microstructure and texture evolution during warm compression of the magnesium alloy AZ31

      Institute of Scientific and Technical Information of China (English)

      GODFREYB; Andy

      2009-01-01

      The evolution of the microstructure and texture with strain during compression at 150℃ of the magnesium alloy AZ31 has been investigated using the electron backscattered diffraction (EBSD) technique. The initial samples were chosen to have a strong basal plane texture with the crystal c-axes perpendicular to the compression direction. The EBSD data provide evidence concerning the relative activity of both {10-12} extension twinning and slip, and suggest that non-basal slip is important in samples deformed to a strain of more than 0.2. The relative contributions of the twinning and the slip during deformation have been discussed based on the results above.

    3. Microstructural Aspects of Damage and Fracture in AZ31 Sheet Materials

      Science.gov (United States)

      Kang, Jidong; Wilkinson, David S.; Mishra, Raja K.; Embury, J. David; Essadiqi, Elhachmi; Javaid, Amjad

      2013-05-01

      There are considerable data in the literature dealing with deformation mechanisms in AZ31 sheets. However, there is little information on the damage and fracture processes in this material. In this contribution, digital image correlation is used to follow deformation patterns occurring during tensile and v-bending tests at room temperature. A variety of surface analysis techniques and three-dimensional x-ray tomography have been used to examine the relationship between deformation, damage initiation, and the final fracture processes. The results show that premature diffuse necking occurs in the tensile tests without transit into localized necking. Deformation twins cluster by an autocatalytic process to form shear bands serving as preferential sites for strain localization and crack initiation. Damage appears in the form of microcracks within the shear bands at a late stage of necking and lead to the final fracture. The presence and the distribution of second-phase particles and their distributions help accelerate the final fracture processes.

    4. Transformation mechanism of lamellar microstructure of AZ80 wrought Mg alloy during warm deformation

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      The microstructure especially the lamellar second phase evolution by a combination of deformation and heat treatment for AZ80 alloy was investigated. The results show that there are finer lamellar Mg17Al12 phases after hot compression with the increasing strain, while there are coarse lamellar discontinuous precipitation cells of β-Mg17Al12 phase spreading from the grain boundaries into the grains after T6 treatment of the compressed samples. The lamellar morphologies especially the lamellar distance of β-Mg17Al12phase precipitation of the T6 treated deformation specimen at different strains differ from each other as there are different grain boundaries in the corresponding compressed specimens.

    5. Influence of isochronal heat treatment on damping behavior of AZ61 alloy

      Institute of Scientific and Technical Information of China (English)

      LIU Chu-ming; LIU Zi-juan; ZHU Xiu-rong; HU Bi-wen; WANG Rong; WANG Meng-jun

      2007-01-01

      Strain amplitude dependence of the logarithmic decrement was measured and studied on an AZ61 magnesium alloy at room temperature. Measurements were carried out before and after isochronal thermal treatment step by step with increasing temperature. For all specimens, the strain dependence of the logarithmic decrement exhibits two regions. At lower strains the logarithmic decrement is strain independent and in the higher strain region it depends strongly on strain amplitude. The strain-independent logarithmic decrement is mainly composed of thermoelastic damping and dislocation damping, which can be temperatures is a little lower than that for as-cast specimen, and it increases with increasing temperature of heat treatment.Microstructure changes due to heat treatment are responsible for changes of the logarithmic decrement.

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

      Science.gov (United States)

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

      2016-07-01

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

    7. 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.

    8. Effects of deformation parameters on microstructure and mechanical properties of magnesium alloy AZ31B

      Institute of Scientific and Technical Information of China (English)

      ZHANG Shaoming; YANG Bicheng; XU Jun; SHI Likai; CHEN Guoliang

      2006-01-01

      Plastic deformation and dynamic recrystallization (DRX) behaviors of magnesium alloy AZ31B during thermal compression and extrusion processes were studied.In addition, effects of deformation temperature and rates on the microstructure and mechanical properties were investigated.The results show that the DRX grains nucleate initially at the primary grain boundaries and the twin boundaries, and the twinning plays an important role in the grain refinement.The DRX grain size depends on the deformation temperature and strain rate The average grain size is only 1 μm when the strain rate is 5 s-1 and temperature is 250 ℃.It is also found that the DRX grain can grow up quickly at the elevated temperature.The microstructure of extruded rods was consisted of tiny equal-axis DRX grains and some elongated grains.The rods extruded slowly have tiny grains and exhibit good mechanical properties.

    9. El legado psicológico de Rogelio Díaz-Guerrero

      OpenAIRE

      Reynaldo Alarcón

      2010-01-01

      O autor identifica quatro dimensões básicas na obra do psicólogo mexicano Rogelio Díaz-Guerrero (1918-2004): a) seu interesse pioneiro por construir uma psicología do mexicano se inicia com a publicação de Estudios de psicología del mexicano (1961) e culmina 42 anos depois com seu livro Bajo las garras de la cultura. Psicología del mexicano 2 (2003); b) a orientação culturalista de seu pensamento; c) sua adesão à psicologia transcultural, em reação ao etnocentrismo psicológico dominante em su...

    10. Reheating microstructure of refined AZ91D magnesium alloy in semi-solid state

      Institute of Scientific and Technical Information of China (English)

      姜巨福; 罗守靖

      2004-01-01

      By means of equal channel angular extrusion (ECAE) test, upsetting test and metalloscope, reheating microstructures of raw casting ingots, materials prepared by SIMA and materials extruded by ECAE in semi-solid state were investigated. The results show that compared with those of raw casting ingots and materials prepared by SIMA, reheating microstructure of materials extruded by ECAE is the best and the final grain size is the finest.With increasing holding time, a growing phenomenon occurs in reheating microstructure of materials extruded by ECAE, which can be described by Ostwald ripening law. The average grain size increases firstly, subsequently decreases and the shape factor of grains approaches to 1 as the reheating temperature increases. With increasing equivalent strain, the average grain size decreases. This demonstrates that reheating material extruded by ECAE technology is a good method to prepare AZ91D magnesium alloy semi-solid billets.

    11. Ram speed profile design for isothermal extrusion of AZ31 magnesium alloy by using FEM simulation

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      In the conventional hot extrusion of metallic materials,the temperature of the workpiece varies during the whole extrusion process,leading to the non-uniformity of the product dimension,microstructure and properties.In the present research,a simulation model based on the principle of PID control was developed to establish ram speed profiles that can suppress the temperature evolution during the process to allow for isothermaI extrusion.With this simulation model,the real-time extrusion ram speed was adjusted according to the simulated exit temperature.The results show that temperature homogeneity is significantly improved not only along the extrudate length but also on its cross section in the case of extrusion in the isothermal mode with a designed ram speed profile in the extrusion process of AZ31 magnesium.In addition,die temperature varies over a more narrow range in comparison with extrusion in the conventional iso-speed mode.

    12. Direct electroless Ni-P plating on AZ91D magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      LI Zhong-hou; QU Yu-ping; ZHENG Feng; DAI A-gan

      2006-01-01

      An electroless Ni-P plating treatment was applied on AZ91D magnesium alloy to improve its corrosion resistance. Optimum pretreatment conditions and optimum bath of electroless nickel plating for magnesium alloy were found through many experiments. In order to avoid bother of pre-plating medium layer, a set of procedure of direct electroless Ni-P under the acid condition was investigated. The properties of the coating with 10% phosphorus were investigated. The results show that a coating with high hardness, low porosity and good adhesive strength is obtained. X-ray diffraction patterns show that the structure of the coating is an amorphous phase. After annealing at 400 ℃, the amorphous phase of Ni-P is transformed to crystalline phases,and some intermetallics as Ni3P and Ni5P2 are deposited from Ni -P solid solution along with an enhancing hardness from Hv 450 to Hv 910.

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

      Science.gov (United States)

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

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

    14. Heat Treated AZ61 Magnesium Alloy Obtained by Direct Extrusion and Continuous Rotary Extrusion Process

      Directory of Open Access Journals (Sweden)

      Bigaj M.

      2016-03-01

      Full Text Available The results of studies carried out on the heat treated AZ61 magnesium alloy extruded by two methods, i.e. direct extrusion and continuous rotary extrusion, were presented. As part of the work, parameters of the T6 heat treatment were proposed and aging curves were plotted. The solution heat treatment process was accompanied by the grain growth. During artificial aging, due to the decomposition of solid solution, the β-Mg17Al12 phase was precipitated from the supersaturated α solution. It precipitated in a coagulated form at the grain boundaries and in the form of fine-dispersed plates arranged in a preferred direction relative to the grain orientation. Rods obtained by continuous rotary extrusion, unlike those made by the direct process, exhibited a low degree of texturing and lack of anisotropic properties.

    15. 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.

    16. Effects of RE on microstructure and properties of AZ91 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      2000-01-01

      AZ91 magnesium alloy was adopted as master alloy and rare earths (RE) of 1%, 2% and 3% additions wereadded, respectively. The influence of RE on the microstructure was investigated. By casting fluidity spiral specimens, effect of RE on fluidity was achieved. The microhardness of the alloys was tested. By casting specimens in permanent mold,tensile properties of the alloys with different RE addition at ambient and elevated temperatures were studied. The fracturemechanisms of the alloys were studied by SEM. RE additions cause the formation of Al11 RE3 precipitation besides phasechange in the alloys. RE firstly decreases and then increases the fluidity. RE has little influence on ambient temperaturetensile properties but greatly improves high temperature tensile properties at 150 C. Tensile failure of the alloys are mainly brittle cleavage and/or quasi-cleavage fracture

    17. 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.

    18. Effects of RE on Microstructures and Mechanical Properties of Hot-Extruded AZ31 Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      刘英; 陈维平; 张卫文; 张大童; 李元元

      2004-01-01

      Effects of rare earth (RE) additions on microstructure and mechanical properties of the wrought AZ31 magnesium alloy were investigated. The results show that, by adding 0.3%, 0.6% and 1.0% RE elements, the as-cast microstructure can be refined, and the as-cast alloys′ elongation and tensile strength can be improved. After extrusion, the alloy with 0.3% and 0.6% RE additions obtain a finer microstructure and the best mechanical properties, but the alloy with 1.0% RE addition has the coarse Al-RE compound particles in grain boundaries which decreased elongation and tensile properties. Usually, Rare earth (RE) elements were used to improve the creep properties of aluminium-containing magnesium pressure die cast alloys at elevated temperatures. In this paper, it is also found that the high temperature strength of extruded materials can be increased by RE elements additions.

    19. 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.

    20. Statistical analysis on static recrystallization texture evolution in cold-rolled AZ31 magnesium alloy sheet.

      Science.gov (United States)

      Park, Jun-Ho; Ahn, Tae-Hong; Choi, Hyun-Sik; Chung, Jung-Man; Kim, Dong-Ik; Oh, Kyu Hwan; Han, Heung Nam

      2013-08-01

      Cast AZ31B-H24 magnesium alloy, comprising Mg with 3.27 wt% Al and 0.96 wt% Zn, was cold rolled and subsequently annealed. Global texture evolutions in the specimens were observed by X-ray diffractometry after the thermomechanical processing. Image-based microstructure and texture for the deformed, recrystallized, and grown grains were observed by electron backscattered diffractometry. Recrystallized grains could be distinguished from deformed ones by analyzing grain orientation spread. Split basal texture of ca. ±10-15° in the rolling direction was observed in the cold-rolled sample. Recrystallized grains had widely spread basal poles at nucleation stage; strong {0001} basal texture developed with grain growth during annealing.

    1. Los derivados de la caña de azúcar en Cuba

      Directory of Open Access Journals (Sweden)

      Marianela Cordovés-Herrera

      2013-01-01

      Full Text Available La agroindustria azucarera cubana ha estado experimentando diferentes transformacio- nes en los últimos años que comenzaron con su redimensionamiento en el año 2002. El crecimiento de la producción de derivados de la caña de azúcar, con énfasis en las pro- ducciones de alimento animal y de alcoholes de diferentes denominaciones, se incluye dentro de las proyecciones de desarrollo del sector, como parte de las soluciones estra- tégicas y altamente valoradas para las esferas de la energía, los alimentos y los biopro- ductos. En el presente trabajo se presenta la actualización de las fábricas de derivados quie existen en Cuba, su localización y capacidades productivas. Se exponen, asimismo, los antecedentes de estas producciones, su actual situación, problemática e influencia en la rentabilidad azucarera.

    2. Influence of Surface Condition on Expulsion in Spot Welding AZ31B Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      Yarong WANG; Jicai FENG; Zhongdian ZHANG

      2005-01-01

      Experiments were carried out to study the influence of surface condition on expulsion during the spot welding of AZ31B Mg alloy. A general electrical contact resistance theory for conductive rough surfaces and the relation between maximum temperature Tm in the contact and voltage-drop V across interface of two surfaces were employed to understand the reason of expulsion in Mg alloy spot welding. The main reason of expulsion is that the high electrical contact resistance induced by large roughness of the surface and oxide film covered on the surface leads to local melting of metal in the interface of two surfaces, and liquid metal of the local area ejected from the specimen under electrode force forms expulsion.

    3. Processing map for hot working of as extruded AZ31B magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      HUANG Guang-sheng; HUANG Guang-jie; WANG Ling-yun; PAN Fu-sheng

      2005-01-01

      The deformation behavior of AZ31B magnesium alloy as extruded under hot compression conditions was characterized in the temperature range of 200 - 400 ℃ and strain rate range of 0. 001 - 1 s-1. The processing maps were obtained at different strains. The results show that the map exhibits flow instabilities as two domains. The domain at beyond 300 ℃ and strain rate of 1 s-1 appears with a peak efficiency of power dissipation about 56% occurring. This domain is expected to happen in a hot process, such as hot rolling, hot extrusion and hot forging. There is high efficiency of power dissipation at temperature beyond 350 ℃ and strain rate 0. 001 s-1. Such domains suggest the occurrence of superplastic deformation.

    4. Grain size and texture changes of magnesium alloy AZ31 during multi-directional forging

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      Grain size and texture changes of magnesium alloy AZ31 were studied in multidirectional forging(MDF) under decreasing temperature conditions. MDF was carried out up to large cumulative strains of 4.8 with changing the loading direction during decrease in temperature from pass to pass. MDF can accelerate the uniform development of fine-grained structures and increase the plastic workability at low temperatures. As a result, the MDFed alloy shows excellent higher strength as well as moderate ductility at room temperature even at the grain size below 1 μm. Superplastic flow takes place at 423 K and depends on the anisotropy of MDFed samples. The mechanisms of strain-induced free-grained structure development and of the plastic deformation were discussed in detail.

    5. Numerical simulation of die filling behavior of AZ91D in the semisolid process

      Directory of Open Access Journals (Sweden)

      Zhu Guanglei

      2010-05-01

      Full Text Available In this work, numerical simulation of the die filling and solidification process of AZ91D semisolid alloy was investigated to produce a thin walled connecting rod demanding a high dimensional precision. The Carreau viscosity model was implemented to simulate the flow behavior of semisolid slurry during the filling. The fitted constants for the Carreau model were used to verify the simulation results. The predicted results from this model were in good agreement with the experimental results. Then the verified Carreau model was designed to predict die filling, casting defects and casting process. It was found that the predicted results had a good correlation with those in the experiment. The optimum parameters were obtained with a slurry temperature of 590 ℃, a die temperature of 250 ℃ and an injection velocity of 2 m/s.

    6. Surface Properties of AZ31B Magnesium Alloy by Oxygen Plasma Immersion Ion Implantation

      Institute of Scientific and Technical Information of China (English)

      WEI Chunbei; GONG Chunzhi; TIAN Xiubo; YANG Shiqin; Ricky K.Y.Fu; Paul K.CHU

      2009-01-01

      Oxygen plasma immersion ion implantation(PIII)has been conducted on AZ31B magnesium alloy using different bias voltages.The modified layer is mainly composed of MgO and some MgAl2O4.Results form Rutherford backscattering spectrometry(RBS)and X-ray photoelectron spectroscopy(XPS)indicate that the bias voltage has a significant impact on the structure of the films.The oxygen implant fluences and the thickness of the implanted layer increase with higher bias voltages.A high bias voltage such as 60 kV leads to an unexpected increments in the oxygen-rich layer's thickness compared to those of the samples implanted at 20 kV and 40 kV.The hardness is hardly enhanced by oxygen PIII.The corrosion resistance of magnesium alloy may be improved by a proper implantation voltage.

    7. On twinning and anisotropy in rolled Mg alloy AZ31 under uniaxial tension

      Directory of Open Access Journals (Sweden)

      Guo Xiaoqian

      2016-01-01

      Full Text Available The Elastic Visco-Plastic Self-Consistent (EVPSC model, with the recently developed Twinning and De-Twinning (TDT description, is applied to study the mechanical behaviour of hot-rolled Mg alloy AZ31 under uniaxial tension. Numerical results are compared to the experimental uniaxial tensile tests reported earlier by Chapuis et al. [29] for the out-of-plane directions of a thick plate along angles of α = 0°, 30°, 45°, 60° and 90° between the normal direction and longitudinal specimen axis. It is shown that accounting for the initial texture and calibrating the EVPSC-TDT model by using uniaxial tension tests along the rolling direction and normal direction permits prediction of the strength anisotropy and strain hardening behavior along all five tensile directions, i.e. for cases in which the contribution of twinning is dominating, negligible or intermediate.

    8. 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.

    9. Co2FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

      Directory of Open Access Journals (Sweden)

      J. Rogge

      2015-07-01

      Full Text Available We succeed to integrate BaO as a tunneling barrier into Co2FeAl based magnetic tunnel junctions (MTJs. By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR ratio of -10% is found for Co2FeAl (24 nm / BaO (5 nm / Fe (7 nm MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM, it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double layer barrier, the electric stability could effectively be increased by a factor of five. The resulting TMR effect is found to be about +20% at room temperature, although a fully antiparallel state has not been realized.

    10. 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.

    11. Microstructural evolution during the hot deformation of magnesium alloy AZ31

      Energy Technology Data Exchange (ETDEWEB)

      Grosvenor, A.; Davies, C.H.J. [Cooperative Research Centre for Cast Metals Mfg. (CAST), School of Physics and Materials Engineering, Monash Univ., Vic. (Australia)

      2003-07-01

      The market for wrought magnesium alloys has lingered around 5000 to 7000 tonnes per year for the past fifteen years or so, and this is partly because of deficiencies in our understanding of the microstructural behaviour which influences formability. This paper examines microstructural evolution in the magnesium alloy AZ31 during hot working. Compression tests were conducted on homogenised AZ31 at three true strain rates -0.01 s{sup -1}, 0.1 s{sup -1}, and 1 s{sup -1} - and five temperatures in 50 C intervals from 200 C to 400 C. In addition, strain rate jump tests were conducted between strain rates of 0.1 s{sup -1}, and 1 s{sup -1} at constant work hardening rate, both in the 'upward' and in the 'downward' sense. Compression tests to a strain of one yielded flow stress curves which are typical of a metal which undergoes dynamic recrystallization, and the presence of the phenomenon was confirmed by metallographic examination of specimens taken from interrupted tests. Twinning was also found to occur at low temperatures and high strain rates, and work hardening curves were found to display a region with little change in gradient, which seemed to confirm this. The strain rate sensitivity was found to decrease with temperature from a value of approximately 0.12 at 400 C to close to 0.02 at 200 C. Colour metallography was used to reveal gross orientation changes with deformation. (orig.)

    12. MICROSTRUCTURAL FORMATION MECHANISM OF SEMI-SOLID AZ91D ALLOY

      Institute of Scientific and Technical Information of China (English)

      W.M. Mao; Z.S. Zhen; H.T. Chen; X.Y. Zhong

      2005-01-01

      With the help of an electromagnetic stirring device and alloy melt quenching technology, the microstructure of semi-solid AZ9lD magnesium alloy slurry stirred by a rotationally electromagnetic field was studied and the experimental results are shown as the following. The primary α-Mg grains are refined obviously when the slurry is stirred by a rotational electromagnetic field during continuously cooling and they are eventually changed to fine rosette grains or spherical grains. If the above semi-solid slurry is further stirred isothermally .for some time,much more spherical primary α-Mg grains can be obtained. If the melt is first cooled down to a given semi-solid temperature and then starts being stirred by the rotational electromagnetic field, the primary α-Mg dendrites will be large, and a longer time will be taken and a larger stirring power will be needed for the secondary arms of the dendrites to be remelted on the roots to prepare an ideal semi-solid slurry. Theoretical analysis indicates that the strong flow motion leads to a more even temperature field and a solute field and stronger man-made temperature fluctuation in the AZ91D magnesium alloy melt so that the spherical primary α-Mg grains are increased in the slurry. Moreover, all the measures promoting the temperature fluctuation will be favorable to the formation of spherical primary α-Mg grains and all the factors increasing the arm's root remelting difficulty will be favorable to the formation of rosette-type primary α-Mg grains.

    13. Mg-Gd-Y与AZ31两种变形镁合金的冲击波响应%Shock-Loading Response of Mg-Gd-Y and AZ31 Wrought Magnesium Alloys

      Institute of Scientific and Technical Information of China (English)

      张帆; 郝敏; 谭成文; 于晓东; 王富耻; 才鸿年

      2012-01-01

      The Mg-Cd-Y and AZ31 magnesium alloys were subjected to shock wave loading by using the plain symmetry impact experiment Then, the uniaxial compression tests were carried out on the recovered shock-deformed samples. Optical microscopy (OM) and transmission electron microscopy (TEM) were used to observe the microstructure. The increased magnitude of the yield strength of the samples for the solutionized and peak-aged Mg-Gd-Y alloy was 21 Mpa and 4 Mpa, respectively. Therefore, the precipitate phase P' in the peak-aged condition was responsible for the decreased shock strengthening. In contrast, the AZ31 alloy showed a more notable shock-strengthening. The'difference of the mechanical behavior between Mg-Gd-Y and AZ31 under shock wave loading was dependent on the discrepancy of deformation mechanisms. The twinning volume fraction for the shock-deformed Mg-Gd-Y alloy was low, indicating that the dominant deformation mechanism was dislocation slip. Whereas, there existed plenty of twinning in the shock deformed AZ31 alloy. The notable shock-strengthening was attributed to the twinning boundary being the obstacles of the dislocation glide in the post-shock reload process.%利用平行平面正碰撞方法产生的冲击波对Mg-Gd-Y与AZ31两种典型变形镁合金加载,并对回收后的材料进行准静态压缩实验,采用金相显微镜和透射电子显微镜进行微观组织分析.冲击波加载后,原始固溶态Mg-Gd-Y合金的屈服强度增加了21 MPa,而时效峰状态合金的屈服强度仅增加4 MPa,时效处理后产生的析出相β’使合金的屈服强度增加幅度明显减少;然而,AZ31镁合金的屈服强度增加了40 MPa.Mg-Gd-Y与AZ31镁合金的冲击波加载后力学响应的差异取决于冲击波过程中两者所具有的不同变形机制,冲击波变形后Mg-Gd-Y合金中的孪晶体积分数非常少,其变形机制以位错滑移为主.相比之下,冲击波加载后的AZ31合金中产生了大量孪晶,孪生是该合

    14. Quantitative Spectroscopy of BA-type Supergiants

      CERN Document Server

      Przybilla, N; Becker, S R; Kudritzki, R P

      2005-01-01

      Luminous BA-SGs allow topics ranging from NLTE physics and the evolution of massive stars to the chemical evolution of galaxies and cosmology to be addressed. A hybrid NLTE technique for the quantitative spectroscopy of BA-SGs is discussed. Thorough tests and first applications of the spectrum synthesis method are presented for four bright Galactic objects. Stellar parameters are derived from spectroscopic indicators. The internal accuracy of the method allows the 1sigma-uncertainties to be reduced to <1-2% in Teff and to 0.05-0.10dex in log g. Elemental abundances are determined for over 20 chemical species, with many of the astrophysically most interesting in NLTE. The NLTE computations reduce random errors and remove systematic trends in the analysis. Inappropriate LTE analyses tend to systematically underestimate iron group abundances and overestimate the light and alpha-process element abundances by up to factors of 2-3 on the mean. Contrary to common assumptions, significant NLTE abundance correction...

    15. Effect of local environment on crossluminescence kinetics in SrF{sub 2}:Ba and CaF{sub 2}:Ba solid solutions

      Energy Technology Data Exchange (ETDEWEB)

      Terekhin, M.A. [P.N. Lebedev Physical Institute, Leninskij Prospekt 53, 119991 Moscow (Russian Federation); Makhov, V.N., E-mail: makhov@sci.lebedev.ru [P.N. Lebedev Physical Institute, Leninskij Prospekt 53, 119991 Moscow (Russian Federation); Lebedev, A.I.; Sluchinskaya, I.A. [Lomonosov Moscow State University, Moscow 119991 (Russian Federation)

      2015-10-15

      Spectral and kinetic properties of extrinsic crossluminescence (CL) in SrF{sub 2}:Ba (1%) and CaF{sub 2}:Ba (1%) are compared with those of intrinsic CL in BaF{sub 2} and are analyzed taking into account EXAFS data obtained at the Ba L{sub III} edge and results of first-principles calculations. The CL decay time was revealed to be longer in SrF{sub 2}:Ba and CaF{sub 2}:Ba compared to BaF{sub 2}. This fact contradicts the expected acceleration of luminescence decay which could result from an increased overlap of wave functions in solid solutions due to shortening of the Ba-F distance obtained in both EXAFS measurements and first-principles calculations. This discrepancy is explained by the effect of migration and subsequent non-radiative decay of the Ba (5p) core holes in BaF{sub 2} and by decreasing of the probability of optical transitions between Ba (5p) states and the valence band in SrF{sub 2}:Ba and CaF{sub 2}:Ba predicted by first-principles calculations. - Highlights: • The crossluminescence kinetics in SrF{sub 2}:Ba and CaF{sub 2}:Ba is slower than in BaF{sub 2}. • Ba{sup 2+} ions substitute for host Ca{sup 2+}(Sr{sup 2+}) ions in the on-center positions. • The nearest Ba-F distances in SrF{sub 2}:Ba and CaF{sub 2}:Ba are shorter than in BaF{sub 2}. • EXAFS data and first-principles calculations of the local structure agree well. • First-principles calculations explain slower luminescence decay in solid solutions.

    16. 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.

    17. Hot compression deformation behavior of AZ31 magnesium alloy at elevated temperature%AZ31镁合金高温热压缩变形特性

      Institute of Scientific and Technical Information of China (English)

      郭强; 严红革; 陈振华; 张辉

      2005-01-01

      在应变速率为0.005~5 s-1、变形温度为250~450℃条件下,在Gleeble-1500热模拟机上对AZ31镁合金的高温热压缩变形特性进行了研究.结果表明:材料流变应力行为和显微组织强烈受到变形温度的影响;变形温度低于350℃时,流变应力呈现幂指数关系;变形温度高于350℃时,流变应力呈现指数关系;变形过程中发生了动态再结晶且晶粒平均尺寸随变形参数的不同而改变,其自然对数与Zener-Hollomon(Z)参数的自然对数成线性关系;材料动态再结晶机制受变形机制的影响,随温度的不同而改变;低温下基面滑移和机械孪晶协调变形导致动态再结晶晶粒的产生;中温时Friedel-Escaig机理下位错的交滑移控制动态再结晶形核;高温时位错攀移控制整个动态再结晶过程.在本实验下,材料的最佳工艺条件是:变形温度350~400℃,应变速率为0.5~5 s-1.

    18. Fatigue behavior of friction stir spot welded AZ31 Mg alloy sheet joints%AZ31镁合金板材搅拌摩擦点焊连接件的疲劳行为

      Institute of Scientific and Technical Information of China (English)

      罗天骄; 史宝良; 段启强; 付俊伟; 杨院生

      2013-01-01

        利用拉压疲劳实验研究 AZ31板材搅拌摩擦点焊连接件的疲劳行为。结果表明:AZ31镁合金板材搅拌摩擦点焊连接件的疲劳失效均发生在搅拌区,疲劳裂纹均起源于搅拌区外侧边缘,位于上下板之间。当循环加载等于1 kN 时,疲劳裂纹沿着热影响区和热机械区界面且垂直载荷的方向扩展;而当循环载荷等于3 kN时,疲劳裂纹则沿着搅拌区直径方向扩展,并最终发生剪切断裂。另外,断口横截面显微分析显示,在AZ31板间搅拌区外侧存在一个“舌状区”,“舌状区”的方向是沿搅拌区向外,疲劳裂纹均起源于“舌状区”。%The fatigue behavior of friction stir spot welded (FSSW) AZ31 magnesium alloy sheet joints was investigated by tension−compression of fatigue test. The results suggest that all the fatigue failures occur at the stir zone of the FSSW AZ31 sheet joints, and all cracks initiate at the stir zone outer edge between the upper and lower sheet. When the cycle force equals 1 kN, the crack propagates along the interface of heat-affected zone and thermo-mechanical zone, simultaneously across the direction of force;while the cycle force equals 3 kN, the crack propagates along the diameter of stir zone and shear failure occurs finally. Moreover, the transverse microsections indicate that there is a tongue-like region at the outer edge of stir zone between the two AZ31 sheets, and the direction of tongue-like region is toward outside of the stirred zone and all fatigue cracks initiate at the tongue-like region.

    19. Effect of Schiff base as corrosion inhibitor on AZ31 magnesium alloy in hydrochloric acid solution%席夫碱作为缓蚀剂对盐酸溶液中AZ31镁合金的影响

      Institute of Scientific and Technical Information of China (English)

      S. THIRUGNANASELVI; S. KUTTIRANI; Amali Roseline EMELDA

      2014-01-01

      Schiff base derived from the condensation reaction of analar grade 1-amino-2-naphthol 4-sulphonic acid with cinnamaldehyde was prepared under microwave condition. The Schiff base was analysed by infrared spectroscopy. This Schiff base as a corrosion inhibitor of AZ31 magnesium alloy in 0.05 mol/L HCl solution was studied. The inhibition effect of the Schiff base compound (4Z)-4-(3-phenyl allylidene amino)-3-hydroxy naphthalene-1-sulfonic acid (AC) on AZ31 magnesium alloy corrosion was studied using mass loss, potentiodynamic polarization technique, electrochemical impedance spectroscopy methods. The potentiodynamic polarization curve shows that Schiff base AC inhibits both anodic and cathodic reactions at all concentration, which indicates it is a mixed type inhibitor. EIS results indicate that as the additive concentration is increased, the polarization resistance increases whereas double-layer capacitance decreases. The adsorption of AC on the AZ31 magnesium alloy surface in 0.05 mol/L HCl obeys the Langmuir adsorption isotherm.%在微波条件下,通过高纯度1-氨基-2萘酚4-磺酸与肉桂醛的缩合反应制备席夫碱(4Z)-4-(3-苯基烯丙叉氨基)-3-羟基萘-1-磺酸(AC)。采用红外光谱对制备的席夫碱进行分析。研究席夫碱作为缓蚀剂对AZ31镁合金在0.05 mol/L 盐酸中的缓蚀作用。通过质量损失法、动电位极化法和电化学交流阻抗谱(EIS)研究席夫碱化合物在 AZ31镁合金腐蚀过程中的抑制作用。动电位极化曲线表明:席夫碱在所有浓度下能抑制阳极和阴极反应,是一种混合型缓蚀剂。EIS结果表明:随着添加剂浓度的增加,极化电阻增加而双电层电容减少。在0.05 mol/L盐酸中,席夫碱AC对AZ31镁合金表面的吸附符合Langmuir吸附等温式。

    20. Microstructure and property of rheocasting AZ91 slurry produced via ultrasonic vibration process%超声振动制备流变铸造AZ91镁合金浆料的微观组织和性能

      Institute of Scientific and Technical Information of China (English)

      尧军平; 孙众; 杨涛; Bharat BBUSHAN; 龙文元; 张磊

      2014-01-01

      研究AZ91镁合金流变铸造的微观组织和力学性能。采用超声振动方法和压铸成型制备镁合金半固态浆料。结果表明:由于超声振动的空化、声流效应,在成核阶段获得细小圆整的初生α-Mg颗粒;随着超声振动时间延长,初生α-Mg颗粒的固相体积分数和平均尺寸增大,但形状系数基本不变,为0.7;在液相线以下温度附近超声振动6 min可获得最佳的AZ91镁合金半固态浆料,其压铸后的拉伸强度和伸长率分别是248 MPa和7.4%。流变铸造AZ91镁合金的断裂机制是韧性断裂。%The microstructure and mechanical properties of rheocasting AZ91 magnesium alloy were investigated. The semisolid slurry of this alloy was prepared by ultrasonic vibration (USV) process and then shaped by high pressure diecasting (HPDC). The results show that fine and spherical α-Mg particles were obtained by USV at the nucleation stage, which was mainly attributed to the cavitation and acoustic streaming induced by the USV. Extending USV treatment time increased the solid volume fraction and average particle size, the shape factors were nearly the same, about 0.7. Excellent semisolid slurry of AZ91 magnesium alloy could be obtained within 6 min by USV near its liquidus temperature. The rheo-HPDC samples treated by USV for 6 min had the maximum ultimate tensile strength and elongation, which were 248 MPa and 7.4%, respectively. It was also found that the ductile fracture mode prevailed in the rheocasting AZ91 magnesium alloy.

    1. Electron paramagnetic resonance studies of the soluble CuA protein from the cytochrome ba3 of Thermus thermophilus.

      Science.gov (United States)

      Karpefors, M; Slutter, C E; Fee, J A; Aasa, R; Källebring, B; Larsson, S; Vänngård, T

      1996-11-01

      The electron paramagnetic resonance (EPR) spectrum of the binuclear CuA center in the water-soluble subunit II fragment from cytochrome ba3 of Thermus thermophilus was recorded at 3.93, 9.45, and 34.03 GHz, and the EPR parameters were determined by computer simulations. The frequency and M1 dependence of the linewidth was discussed in terms of g strain superimposed on a correlation between the A and g values. The g values were found to be gx = 1.996, gy = 2.011, gz = 2.187, and the two Cu ions contribute nearly equally to the hyperfine structure, with magnitude of Ax magnitude of approximately 15 G, magnitude of Ay magnitude = 29 G, and magnitude of Az magnitude of = 28.5 G (65Cu). Theoretical CNDO/S calculations, based on the x-ray structure of the Paracoccus denitrificans enzyme, yield a singly occupied antibonding orbital in which each Cu is pi*-bonded to one S and sigma*-bonded to the other. In contrast to the equal spin distribution suggested by the EPR simulations, the calculated contributions from the Cu ions differ by a factor of 2. However, only small changes in the ligand geometry are needed to reproduce the experimental results.

    2. A Dubious Distinction? The BA versus the BS in Psychology

      Science.gov (United States)

      Pfund, Rory A.; Norcross, John C.; Hailstorks, Robin; Aiken, Leona S.; Stamm, Karen E.; Christidis, Peggy

      2016-01-01

      Previous studies have documented small differences between the bachelor of arts (BA) and the bachelor of science (BS) psychology degrees in their general education core requirements, particularly mathematics and science courses. But are there differences between the BA and BS degrees within the psychology curriculum? Using data from the…

    3. Solubility of Ba in Liquid Iron and Interaction Effect of the Third Elements

      Institute of Scientific and Technical Information of China (English)

      2000-01-01

      Experiments were carried out at 1 873 K in a double-temperature zone furnace using vapor pressure method. The equilibrium tests of barium vapor with liquid iron were conducted in CaO crucibles sealed in a Mo chamber. As a result, the experiments obtained the relation between the dissolved content of Ba in liquid iron and the vapor pressure of Ba, and the standard Gibbs energies for the reactions Ba(g)=[Ba] and Ba(l)=[Ba].

    4. Radioactive contamination of BaF2 crystal scintillator

      CERN Document Server

      Polischuk, O G; Bernabei, R; Cappella, F; Caracciolo, V; Cerulli, R; Di Marco, A; Danevich, F A; Incicchitti, A; Poda, D V; Tretyak, V I

      2013-01-01

      Barium fluoride (BaF$_2$) crystal scintillators are promising detectors to search for double beta decay processes in $^{130}$Ba ($Q_{2{\\beta}}$ = 2619(3) keV) and $^{132}$Ba ($Q_{2{\\beta}}$ = 844(1) keV). The $^{130}$Ba isotope is of particular interest because of the indications on 2${\\beta}$ decay found in two geochemical experiments. The radioactive contamination of BaF$_2$ scintillation crystal with mass of 1.714 kg was measured over 113.4 hours in a low-background DAMA/R&D set-up deep underground (3600 m w.e.) at the Gran Sasso National Laboratories of INFN (LNGS, Italy). The half-life of $^{212}$Po (present in the crystal scintillator due to contamination by radium) was estimated as $T_{1/2}$ = 298.8 $\\pm$ 0.8(stat.) $\\pm$ 1.4(syst.) ns by analysis of the events pulse profiles.

    5. Superconductivity in Ba(Pb,Bi,Sb)O 3, Ba(Pb,Bi,Te)O 3 and (Ba,La) (Pb,Bi,Tl)O 3 systems

      Science.gov (United States)

      Nagarajan, R.; Vasanthacharya, N. Y.; Gopalakrishnan, J.; Rao, C. N. R.

      1991-02-01

      It is possible to substitute Bi in the superconducting BaPb 0.75Bi 0.25O 3 by Sb or Te without destroying the superconductivity. With Sb, a continuous series of solid solutions BaPb 0.75Bi 0.25-ySb yO 3 (0 ⩽ y ⩽ 0.25) exists, while with Te, perovskite BaPb 0.75Bi 0.25-yTe yO 3 exists only upto y = 0.15. With increasing substitution by Sb or Te, T c decreases continously in both the systems. Superconductivity with a maximum T c of 8K is found in Ba 0.9La 0.1Pb 0.9-yBi yTl 0.1O 3 for y = 0.25.

    6. 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

    7. Neutron Diffraction Study of the Structures of Ba5CuIr3O12 and Ba16Cu3Ir10O39

      NARCIS (Netherlands)

      Blake, Graeme R.; Battle, Peter D.; Sloan, Jeremy; Vente, Jaap F.; Darriet, Jacques; Weill, François

      1999-01-01

      The crystal structures of Ba5CuIr3O12 and Ba16Cu3Ir10O39 have been determined using a combination of X-ray and neutron powder diffraction data. Considering their structures to be based on hcp stacks of Ba3O9 and Ba3CuO6 layers, Ba5CuIr3O12 has a 10-layer structure, space group P3c1 with a = 10.14055

    8. Az internet szerepe a magyar mint idegen nyelv oktatásban.

      OpenAIRE

      Németh, Szabolcs

      2011-01-01

      Internet-based language teaching and e-learning are very popular topics nowadays. Many studies have been published on the subject, especially related to ESL. This article aims at describing internet-based resource materials that can be used in language class for learning and teaching Hungarian as a Second Language. It will present two websites specifically designed for learning Hungarian and different e-learning projects in order to discuss the basic differences between text-ba...

    9. 基于BP神经网络的AZ91镁合金均匀化后的力学性能研究%Mechanical properties of AZ91 magnesium alloy after homogenizing annealing based on BP neural network

      Institute of Scientific and Technical Information of China (English)

      吴雄喜

      2013-01-01

      Based on BP neural network,the mechanical properties parameters of AZ91 magnesium alloy under different annealing conditions were obtained by homogenizing annealing. The results show that BP neural network can map relationship between heat treatment process and material properties very well,and prediction accuracy is very good.%基于BP神经网络法,利用均匀化退火工艺改善AZ91镁合金的组织结构,获得了不同退火状态下材料的力学特性参数。结果表明,BP神经网络能够很好地映射热处理工艺与材料性能间的关系,实验值与预测值重合度很好。

    10. 锑和混合稀土对AZ31镁合金高温变形行为的影响%Effect of Antimony and Rare Earth on Hot Deformation Behavior of AZ31 Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      马庆波; 刘胜新; 李庆奎; 刘俊; 李双喜; 关绍康; 陈永

      2007-01-01

      借助Gleeble-1500D型热模拟试验机,研究了锑和混合稀土对AZ31镁合金在不同温度下(260~420 ℃)的热压缩流变应力和动态再结晶的影响.结果表明:AZ31镁合金的变形抗力随变形温度的升高逐渐减小;分别加入质量分数为1%RE和1%Sb后,其变形抗力显著增大,同时有效促进了热变形过程中的动态再结晶.

    11. 大塑性变形下变形速率对AZ31合金成形性能的影响%Effect of Deformation Rate on Formability of AZ31 Alloy Under Large Plastic Deformation

      Institute of Scientific and Technical Information of China (English)

      刘明朴; 彭晓东; 刘军威; 谢卫东

      2010-01-01

      采用等温挤压成形工艺研究了大塑性变形下变形镁合金AZ31的成形性能,分析了成形过程中变形速率对成形性、成形力和应变的影响.结果表明,AZ31合金在300~350℃等温挤压成形,随变形速率的升高,挤压变形力呈下降的趋势;变形速率为1 mm/s时,应变分布均匀,能够获得最佳的成形质量和力学性能.

    12. Flow Stress Behavior of AZ31magnesium Alloy During Hot Compression Deformation at Elevated Temperature%AZ31镁合金的高温热压缩流变应力行为的研究

      Institute of Scientific and Technical Information of China (English)

      郭强; 张辉; 陈振华; 严红革; 夏伟军; 傅定发

      2004-01-01

      在Gleeble-1500热模拟机上对AZ31镁合金在应变速率为0.005~5 s-1、变形温度为250~450 ℃条件下的流变应力行为进行了研究.结果表明:流变应力行为强烈地受到变形温度的影响,当变形温度低于300 ℃时,流变应力呈现幂指数关系;当变形温度高于350 ℃时,流变应力呈现指数关系.在本实验条件下,AZ31镁合金热变形应力指数n为7,其热变形激活能Q为112 kJ/mol.

    13. Research on Production Control of High Purity AZ91D Magnesium Alloy in Bionic Inlay Casting Process%仿生镶嵌铸造用高纯度AZ91D镁合金生产控制研究

      Institute of Scientific and Technical Information of China (English)

      万元元; 樊富友; 陈明; 程远胜

      2013-01-01

      以生产镁合金/钢仿生镶嵌铸造件用高纯净度AZ91D镁合金为出发点,从原材料及辅料的选择和检验、镁合金熔体保护方式及合金精炼方法、合金熔体夹杂物炉前检测控制等方面着手,通过设计坩埚内保护气体释放装置、炉前断口试样模具及断口判别方法等手段,总结出了用于生产镁合金/钢仿生镶嵌铸造件的高纯净度AZ91D镁合金品质控制方法.

    14. 形变AZ91D镁合金重熔过程中共晶激活能研究%Eutectic Melting Activity Energy of AZ91D Magnesium Alloy by SIMA Method

      Institute of Scientific and Technical Information of China (English)

      王武孝; 邢建东

      2008-01-01

      采用DSC技术研究了SIMA法制备半固态AZ91D镁合金坯料过程中形变率与共晶熔化激活能的关系.结果表明:形变AZ91D镁合金内部存在位错、孪晶缺陷,合金的共晶熔化激活能随变形率的增大而变小,当形变率达到40%时,共晶熔化激活能下降很少;共晶熔化开始温度随变形率的增大略有下降.

    15. Study on the Inhibiting Ability of Hexamethylenetetramine to AZ31 Magnesium Alloy%六次甲基四胺对AZ31镁合金的缓蚀作用研究

      Institute of Scientific and Technical Information of China (English)

      封雪松; 司玉军; 熊中平; 张胜涛

      2009-01-01

      为了表征六次甲基四胺(HMTA)对AZ31镁合金在MgSO4溶液中的缓蚀性能,用线性电位扫描、电化学阻抗谱等方法研究了合金在溶液中的电化学行为.结果表明,少量HMTA的加入能使AZ31镁合金的开路电位正移,极化电阻增大,从而发挥缓蚀效果.HMTA的添加量在0.1~0.15mmol/L范围时具有较好的缓蚀性能,并使活化电位负移,确保合金具有较好的电化学活性.

    16. Innovative methodology for the synthesis of Ba-M hexaferrite BaFe{sub 12}O{sub 19} nanoparticles

      Energy Technology Data Exchange (ETDEWEB)

      Ahmed, M.A., E-mail: moala@47hotmail.com [Materials Science Lab. (1), Physics Department, Faculty of Science, Cairo University, Giza (Egypt); Helmy, N. [Physics Department, Faculty of Science and Art - Girls Branch, Baha University, Bilgurashy (Saudi Arabia); El-Dek, S.I. [Materials Science Lab. (1), Physics Department, Faculty of Science, Cairo University, Giza (Egypt)

      2013-09-01

      Graphical abstract: Transmission electron microscope images for the BaFe12O19. - Highlights: • BaFe{sub 12}O{sub 19}nanoparticles were prepared in single-phase from organometallic precursors. • BaFe{sub 12}O{sub 19} possesses small size 65 nm, H{sub C} = 3695 Oe and M{sub s} = 58 emu/g. • This method of preparation could be extended in the synthesis of other metal oxide nanoparticles. - Abstract: In this piece of work, high quality and homogeneity, barium hexaferrite (BaM) BaFe{sub 12}O{sub 19} nanoparticles were prepared from organometallic precursors for the 1st time. This method is based on the formation of supramolecular crystal structure of Ba[Fe(H{sub 3}NCH{sub 2}CH{sub 2}NH{sub 3})]Cl{sub 7}·8H{sub 2}O. The crystal structure, morphology and magnetic properties of BaFe{sub 12}O{sub 19} at two different annealing temperatures namely 1000 °C and 1200 °C were investigated using X-ray diffraction, transmission electron microscope TEM and vibrating sample magnetometry (VSM). The results show that monophasic nanoparticles of hexaferrites were obtained. Nanoparticles of crystallite size 40–50 nm distinguished by narrow distribution and excellent homogeneity were obtained with superior magnetic properties which suggested single-domain particles of Ba-M hexaferrite.

    17. Study on Electrochemical Corrosion Behaviour of Micro-arc Oxidation Film on AZ91D AHoy%AZ91D镁合金的微弧氧化陶瓷层电化学腐蚀行为研究

      Institute of Scientific and Technical Information of China (English)

      王文礼

      2011-01-01

      The micro-arc oxidation film on AZ91D Mg alloy in the different solutions as aluminates and zirconate was studied by measuring the steady state I/E recording and Tafel slope coefficient with an IM6e electrochemical active station. The corrosion behavior of the film was also analyzed. The results indicate that the micro-arc oxidation films protect the AZ91D magnesium alloy against spot corrosion, and that the corrosion current reduces obviously. The corrosion resisting property of the AZ91D Mg alloy improves visibly.%利用微弧氧化技术对AZ91D镁合金在铝酸盐和锫盐溶液中进行表面陶瓷化处理.采用IM6e型电化学工作站,对微弧氧化镁合金进行电化学稳态电流/电位极化曲线测量以及塔费尔斜率测量.通过电化学测量对微弧氧化镁合金的腐蚀行为进行分析.结果表明:镁合金经微弧氧化处理后,点蚀的发生受到限制,镁合金微弧氧化试样的腐蚀电流较原始试样降低4~6个数量级.镁合金微弧氧化试样的耐蚀等级均达到耐蚀以上的等级.

    18. High Temperature Tension-compression Asymmetry of As-cast AZ31 Alloy%铸态AZ31镁合金高温拉-压不对称性研究

      Institute of Scientific and Technical Information of China (English)

      官磊; 成波

      2012-01-01

      利用Gleeble-1500在250~500℃和应变速率0.001~1 s-1对铸态AZ31镁合金进行热压缩及热拉伸试验,对热变形过程中拉-压不对称性进行研究;基于Hollomon公式,分析了铸态AZ31镁合金热拉伸-压缩过程中应变硬化指数的变化规律.结果表明:铸态镁合金在热拉伸-压缩过程中,存在明显拉-压不对称性,热拉伸应变硬化指数均比热压缩应变硬化指数大;升高形变温度及降低应变速率有利于减小铸态镁合金的拉-压不对称性.%The high temperature tension-compression asymmetry of as-cast AZ31 alloy was studied at 250-500℃ with various strain rates 0.001-ls-1 by Gleeble-1500 dynamic material testing machine. The strain hardening exponents during high temperature tension-compression asymmetry were analyzed by introducing Hollomon equation. The results indicate that during the high temperature tension-compression of as-cast AZ31 alloy, the tension-compression asymmetry is obvious, and the strain hardening exponent of tension is bigger than those of compression. The higher deformation temperature and slower strain rate can decrease the tension-compression asymmetry.

    19. EBSD技术在研究AZ31镁合金挤压织构中的应用%Application of EBSD technique on the study of the texture of extruded AZ31 magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      李娜丽; 黄光杰; 刘庆

      2011-01-01

      AZ31镁合金挤压棒材在传统正挤压变形过程中易于形成很强的挤压纤维织构.本文利用EBSD技术对AZ31镁合金挤压棒材的挤压组织进行了表征,发现AZ31镁合金挤压棒材在挤压时形成的织构不是均匀的(0002)基面平行于挤压方向的环状纤维织构,而是由(10-10)棱柱面垂直于挤压方向和(11-20)棱柱面垂直于挤压方向的两个不同的纤维织构组分组成的.因此(0002)极图不足以表达该织构的足够信息,必须用沿挤压方向的反极图表示.纤维织构的存在使得挤压样品具有明显的拉伸各向异性.%AZ31 magnesium alloy was easy to form strong fiber texture during conventional forward extrusion. In this study, a typical extrusion microstructure was characterized by EBSD technique. The result showed the texture of the extruded sample was not a uniform ring fiber texture with all the (0002) basal plane parallel to extrusion direction, but a fiber texture consists of two different texture component with (10 10) prismatic plan perpendicular to extrusion direction and (11 20) prismatic plane perpendicular to extrusion direction. Hence,(0002) pole figure could not show all the information of the texture, while inverse pole figure in extrusion direction was a more appropriate method. Anisotropy of tensile properties was caused by the fiber texture.

    20. 渗注锆酸盐对AZ31镁合金疲劳裂纹扩展速率的影响%Effects of the Zirconate Deposition on Fatigue Crack Growth Rate in AZ31 Magnesium Alloy

      Institute of Scientific and Technical Information of China (English)

      贺显聪; 王章忠; 白允强; 巴志新; 周衡志; 沈鸿烈

      2011-01-01

      The zirconate deposition behavior and effects of the zirconate on fatigue crack growth rate at the fatigue crack tip of AZ31 magnesium alloy under alternate loads were investigated. The morphology and components of the zirconate deposition at the fatigue crack tip were characterized by means of scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), and X-ray diffractometry (XRD), respectively. The stress intensity factors at the fatigue crack tips with and without zirconate deposition were measured by taking advantage of strain gauge. The results show that the zirconate (ZrxOy ZnxOy) films can be formed at the fatigue crack tips of AZ31 magnesium alloy. The stress intensity factor value is decreased about 40%, which effectively yields fatigue crack closure, reduce or even vanishes the fatigue crack growth rate.%研究交变载荷作用下,在AZ31镁合金疲劳裂纹尖端渗注锆酸盐的沉积行为及其对疲劳裂纹扩展速率的影响.用扫描电镜(SEM)、能谱仪(EDS)及X射线衍射仪(XRD)观察分析裂纹尖端的形貌和物相成分,采取贴应变片方法确定渗注锆酸盐前后应力强度因子的变化.结果表明:锆酸盐转化液能在AZ31镁合金疲劳裂纹尖端形成锆酸盐ZrxOyZnxOy覆层;渗注锆酸盐后裂纹尖端应力强度因子降低约40%,能有效增强疲劳裂纹闭合效应,降低或延滞其疲劳裂纹扩展速率.

    1. Spectroscopy of Ba and Ba$^+$ deposits in solid xenon for barium tagging in nEXO

      OpenAIRE

      Mong, B.; Cook, S; Walton, T.; Chambers, C.; Craycraft, A.; Benitez-Medina, C.; Hall, K.; Fairbank Jr., W.; Albert, J. B.; Auty, D. J.; Barbeau, P. S.; Basque, V.; Beck, D.; Breidenbach, M.; Brunner, T.

      2014-01-01

      Progress on a method of barium tagging for the nEXO double beta decay experiment is reported. Absorption and emission spectra for deposits of barium atoms and ions in solid xenon matrices are presented. Excitation spectra for prominent emission lines, temperature dependence and bleaching of the fluorescence reveal the existence of different matrix sites. A regular series of sharp lines observed in Ba$^+$ deposits is identified with some type of barium hydride molecule. Lower limits for the fl...

    2. REVIEW: TALES OF KHA BA DKAR PO

      Directory of Open Access Journals (Sweden)

      Jundan (Jasmine Zhang

      2015-03-01

      Full Text Available Review of: Jing Guo . 2012. Xue shan zhi shu [Tales of Kha ba dkar po] [ཁ་བ་དཀར་པོ]. Kunming: Yunnan People's Press. My favorite color is to add a little white on the whiteness, as if there was a snow-white eagle landing on a snow-covered mountain rock. My favorite color is to add a bit green on the greenness, as if there was an emerald parrot flying in the wild walnut woods. Deqin xianzi lyrics. These lyrics evoke a space beyond a sense of realism. In his book, Tales of Kha ba dkar po (ToK, Guo mentions these lines three times, suggesting a transcendental experience one may encounter in Tibetan areas while, at the same time, humbled by the mindset of human nature relations enacted by Tibetan people. ToK is, in many ways, a valuable academic work. Guo's favorite lines of xianzi allude to a 'space-in-between' the secular and sacred, which provides a unique experience for a broad readership, and induces the readers to deeper reflections on topics such as 'nature/ culture', 'belief', 'rite', and 'life/ death'. ToK is one of nineteen contemporary anthropological and ethnological works conducted in Yunnan Province, Southwest China and published in the 'Anthropology and Ethnology series in Contemporary China'. In the preface for the series, Yin (2012 suggests that there are two primary reasons for the somewhat slow development of Chinese scholarship in the field of anthropology and ethnology. One is the historically Han-centered intellectual atmosphere, and the other is the ideological ambivalence that ethnic culture has faced since the establishment of the People's Republic of China. In this context, Guo's longitudinal academic and intellectual engagement with the Tibetan communities in northwest Yunnan is included in this series as part of the increasing recognition of the significance of understanding southwest China's complex ethnic and cultural diversity.

    3. X-ray absorption spectroscopy of doped BaCeO3-BaZrO3 systems

      Science.gov (United States)

      Basu, S.; Sawant, P.; Varma, S.; Wani, B. N.; Bharadwaj, S. R.; Jha, S. N.; Bhattacharyya, D.

      2012-06-01

      A solid solution of BaCeO3-BaZrO3 combines the high protonic conductivity of BaCeO3 in presence of hydrogen containing atmospheres at elevated temperatures and appreciable chemical and mechanical stability of BaZrO3 towards water and CO2. EXAFS measurements on the BaCe0.8-xZrxY0.2O3-δ system with x = 0, 0.2, 0.4, 0.6, 0.8 at the Y (dopant) K-edge (17046 eV) were carried out. Two different structural phases were identified as a consequence of change in the doping concentrations.

    4. 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.

    5. Early Science with the Large Millimeter Telescope: CO and [C II] Emission in the z=4.3 AzTEC J095942.9+022938 (COSMOS AzTEC-1)

      CERN Document Server

      Yun, Min S; Gurwell, M A; Hughes, D H; Montaña, A; Narayanan, G; González, D Rosa; Sánchez-Argüelles, D; Schloerb, F P; Snell, R L; Vega, O; Wilson, G W; Zeballos, M; Chavez, M; Cybulski, J R; Díaz-Santos, T; De la Luz, V; Erickson, N; Ferrusca, D; Gim, H B; Heyer, M H; Iono, D; Pope, A; Rogstad, S M; Scott, K S; Souccar, K; Terlevich, E; Terlevich, R; Wilner, D; Zavala, J A

      2015-01-01

      Measuring redshifted CO line emission is an unambiguous method for obtaining an accurate redshift and total cold gas content of optically faint, dusty starburst systems. Here, we report the first successful spectroscopic redshift determination of AzTEC J095942.9+022938 ("COSMOS AzTEC-1"), the brightest 1.1mm continuum source found in the AzTEC/JCMT survey (Scott et al. 2008), through a clear detection of the redshifted CO (4-3) and CO (5-4) lines using the Redshift Search Receiver on the Large Millimeter Telescope. The CO redshift of $z=4.3420\\pm0.0004$ is confirmed by the detection of the redshifted 158 micron [C II] line using the Submillimeter Array. The new redshift and Herschel photometry yield $L_{FIR}=(1.1\\pm0.1)\\times 10^{13} L_\\odot$ and $SFR = 1300\\, M_\\odot$ yr$^{-1}$. Its molecular gas mass derived using the ULIRG conversion factor is $1.4\\pm0.2 \\times 10^{11} M_\\odot$ while the total ISM mass derived from the 1.1mm dust continuum is $3.7\\pm0.7 \\times 10^{11} M_\\odot$ assuming dust temperature of ...

    6. Finite Element Analysis on Backward Extrusion Process for Vacuum Cup Inner Cylinder of AZ31 Magnesium Alloy%AZ31镁合金保温杯内筒反挤压成形模拟研究

      Institute of Scientific and Technical Information of China (English)

      钟兵

      2012-01-01

      运用DEFORM-3D有限元分析软件模拟了AZ31镁合金保温杯内筒反挤压过程,分析了温度和挤压速度对AZ31镁合金反挤压过程中的等效应力、挤压力的影响.模拟结果表明:凸模圆角处的等效应力值最大;随着温度的升高,所需要的最大挤压力变小;挤压速度越大,最大挤压力越大.%The backward extrusion process for the vacuum cup inner cylinder of AZ31 magnesium alloy was simulated by DEFORM-3D finite element software. The effects of the temperature and the extrusion speed on the equivalent stress and extrusion force were analyzed. The results show that the maximum equivalent stress was mainly concentrated around the punch round. With temperature increasing, the maximum extrusion force decreases. The greater the extrussion speed, the larger the maximum extrusion force.

    7. Effects of Modification by Ca and Hot Extrusion on Microstructure of AZ31 Magnesium Alloy%Ca变质及热挤压对AZ31镁合金组织的影响

      Institute of Scientific and Technical Information of China (English)

      林继兴

      2009-01-01

      研究了金属Ca变质处理及热挤压变形对镁合金组织、晶粒大小的影响.结果表明:0.4%的Ca能使AZ31镁合金的β-Mg_(17)Al_(12)组织明显球化,均匀化处理后晶粒尺寸由变质前的546μm降至147μm;另外,400℃下热挤压也能强烈地细化组织,平均晶粒尺寸降至20μm以下,其机理是发生了动态再结晶与孪生变形.%The effects of modification by Ca and hot extrusion on microstructure and grain size of AZ31magnesium alloy were investigated. The results show that the shape of β-Mg_(17)Al_(12) spheroidize is obvious with the addition of 0.4% Ca in the alloy, and the grain size reduces from 546 μm to 147 μm after homogenization treatment. Meanwhile, because of the dynamic recrystallization and twinning deformation, the microstructure of AZ31 magnesium alloy would be refined by hot extrusion under 400℃, and the average grain size decreases, to below 20 μm.

    8. 粉末冶金法制备超细晶AZ31镁合金及超塑性变形研究%Powder Metallurgy Prepared Ultra-fine Grain AZ31 Alloy and Its Superplastic Deformation

      Institute of Scientific and Technical Information of China (English)

      林莺莺; 胡杰仁

      2013-01-01

      采用粉末冶金法制备超细晶AZ31镁合金材料,并对其微观组织形貌及相成分进行研究;利用单向拉伸试验研究了该材料在不同条件下超塑性变形.结果表明,采用球磨、冷压制坯和热挤压法可获得晶粒尺寸在1微米以下的超细晶组织,该材料在250℃,1×10-3s-1的应变速率条件下获得了最大伸长率,基本达到超塑性状态.%Ultra-fine grain AZ31 alloy bars were fabricated by power metallurgy process,and the microstructure and phase composition were also researched.The superplastic deformation was studied by simple tension test.According to the results,AZ31 alloy with the grain size under 1 μm was prepared by the process of high energy ball milling,cold compacting and hot extrusion.The superplastic deformation was achieved under the temperature of 250 ℃ and strain rate of 1 × 10-3 s-1.

    9. AZ31镁合金高温热压缩流变应力行为的研究%Flow stress behavior of AZ31 magnesium alloy during hot compression deformation at elevated temperature

      Institute of Scientific and Technical Information of China (English)

      徐静; 戚文军; 黄正华; 周楠

      2013-01-01

      在Gleeble 1500D型热模拟试验机上,在应变速率为0.01~1 s-1、变形温度为573~723 K条件下,对AZ31合金的流变应力行为进行了研究.结果表明:AZ31镁合金在热压缩变形时,当应变速率-定时,流变应力随着变形温度的升高而减小;而当变形温度一定时,流变应力随着应变速率的增大而增大;该合金的热压缩流变应力行为可用双曲正弦形式的本构方程来描述,在本实验条件下AZ31镁合金热变形应力指数n=8.34,其热变形激活能Q=196 kJ/mol.

    10. AZ31镁合金铸轧板热变形过程的空洞演化%Cavity characteristics of twin-roll casting AZ31 magnesium alloy sheets during hot deformation

      Institute of Scientific and Technical Information of China (English)

      赵虎; 何良菊; 李培杰; 李华伦; 许月旺

      2011-01-01

      分析了AZ31镁合金铸轧板在200-400℃、4×10-4 s-1变形条件下的空洞形核和长大机制.采用原位拉伸试验观察空洞形核位置和长大过程.通过电子背散射衍射技术观察了不同变形条件下AZ31镁合金铸轧板的晶界取向差.在低温变形条件下,空洞尺寸较小,呈圆形,在高温变形条件下,空洞在变形过程中被拉长,其尺寸较大.空洞首先在晶界或三叉晶界处形核之后长大.AZ31镁合金铸轧板中大角晶界相对分数大于80%.尺寸小于2μm的空洞呈球形,其长大机制为扩散控制长大机制.大尺寸空洞在变形过程中发生聚合,其长大机制受塑性和超塑性扩散机制控制.

    11. Hot extrusion deformation of AZ31 magnesium alloy and mechanics performance analysis%AZ31镁合金的热挤压变形和力学性能分析

      Institute of Scientific and Technical Information of China (English)

      石磊; 李继文; 李永兵; 魏世忠; 徐流杰; 张国赏

      2009-01-01

      为了掌握高精度镁合金管材的生产工艺,通过对铸锭的均匀化处理,借助500 t挤压机、拉伸试验机、金相显微镜和透射电镜(TEM)对AZ31镁合金管材的等温挤压过程进行了研究,试制了AZ31镁合金挤压薄壁管材,获得了尺寸精度高、粗糙度小和壁厚差小的管材;分析了不同挤压条件下的AZ31镁合金管材的尺寸精度、组织、力学性能.研究结果表明:在挤压温度为623士20K挤出管材经523K×3h退火时其性能较好,抗拉强度、屈服强度和延伸率分别为270 MPa,175 MPa和23.1%.

    12. Connection of AZ31B Magnesium Alloys and TC4 Titanium Alloy Via Resistance Spot Welding%AZ31B镁合金与TC4钛合金之间的电阻点焊连接

      Institute of Scientific and Technical Information of China (English)

      谈芬芳; 谢志雄; 杜康; 梅张强

      2013-01-01

      In order to make it became realistic that welding of AZ31B magnesium alloys and TC4 titanium alloy via resistance spot welding, in this work the theory of diffusion welding was used. The welding technology of AZ31B magnesium alloys and TC4 titanium alloy aluminum was discussed. In the process, aluminium foil and aluminium powder were used. The property and microstructure of welding spot were analysised by scanning electron microscope (SEM) and X-ray energy dispersion spectroscope (EDS). The results indicate that the mechanical performace of welding sopt is better when aluminiun powder as additive, the diffusion of elements and alloying reaction are conducive to improve the machanical property of welding spot.%为实现AZ31B镁合金与TC4钛合金异种材料的电阻点焊连接,借助扩散焊原理,探讨了在其之间添加铝箔和铝粉的电阻点焊工艺,并对焊点的力学性能及微观结构进行了分析.结果表明,以铝粉作为添加物,可以获得力学性能较好的焊点,元素间的扩散及合金化反应是焊点性能得以提高的主要原因.

    13. Texture Evolution of Extruded AZ31 Magnesium Alloy under Tensile Testing%挤压态AZ31镁合金拉伸变形织构分析

      Institute of Scientific and Technical Information of China (English)

      张诗昌; 梅秋平; 田甜; 杨倩

      2013-01-01

      The inverse pole figures of grain face were calculated with X-ray diffraction patterns to understand the texture evolution of the extruded AZ31 magnesium alloy during tensile deformation. The results show that the strong basal texture (0002) appears, and some grains arranged with C axis are inclined 16°—21° to the extruded direction in the as-extruded samples. The tensile deformation weakens the basal texture and makes the prismatic (1010) plane rotate 45° with C axis.%根据X射线衍射图谱绘制了晶面反极图,研究了拉伸变形对挤压态AZ31镁合金织构的影响.结果表明,挤压态AZ31镁合金具有明显的(0002)基面织构,且存在C轴与挤压方向呈16°~21°角分布的倾斜基面织构.拉伸变形使基面织构弱化,(1010)柱面沿C轴发生了45°角的转动.

    14. Structural Transformation of Hexagonal (0001)BaTiO3 Ceramics to Tetragonal (111)BaTiO3 Ceramics

      Science.gov (United States)

      Watanabe, Takayuki; Shimada, Mikio; Aiba, Toshiaki; Yabuta, Hisato; Miura, Kaoru; Oka, Kengo; Azuma, Masaki; Wada, Satoshi; Kumada, Nobuhiro

      2011-09-01

      A ceramic slurry that contains a 6H-type Ba(Ti0.95Mn0.05)O3 powder was casted into a plaster mold under 10 T magnetic field to form a green compact of (0001)-oriented Ba(Ti0.95Mn0.05)O3. After sintering the green compact at 1300 °C in air, it was confirmed that the (0001)-oriented 6H-type perovskite structure transformed to a (111)-oriented 3C-type perovskite structure. The structural transformation was again examined using hexagonal BaTiO3 prepared by reducing pseudo-cubic BaTiO3 powder in H2 atmosphere. In this case, the preferred (0001) orientation was not confirmed for the green compacts. After sintering the green compacts at 1300 °C in air, mixed crystal orientations of (100)/(001) and (111) were observed for the resultant tetragonal BaTiO3 ceramics. This (100)/(001) orientation was suppressed by annealing the hexagonal BaTiO3 powder at 1000 °C before slip-casting, leading to highly (111)-oriented ceramics. It was found that the green compacts of (0001)-oriented hexagonal BaTiO3 can transform into (111)-oriented tetragonal BaTiO3 ceramics, maintaining the macroscopic crystal orientations due to a similar atomic stacking along [0001] of 6H-type BaTiO3 and [111] of 3C-type BaTiO3.

    15. 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.

    16. Corrosion of Artificial Aged Magnesium Alloy AZ80 in 3.5 wt pct NaCl Solutions

      Institute of Scientific and Technical Information of China (English)

      Rongchang ZENG; Enhou HAN; Wei KE

      2007-01-01

      The corrosion morphologies of aged magnesium alloy AZ80 were investigated by immersion corrosion tests,scanning electron microscopy (SEM), electrochemical measurement. The T5 heat treatment was carried out in a vacuum furnace, holding for 16 h at 177℃, and then cooling in air. The results showed intergranular corrosion (IGC) occurred as an aged AZ80 sample was immersed in 3.5 wt pct NaCl aqueous solution for 1 h and the narrow path attack progressed predominantly along the bulk β phase in the grain boundaries or took place in the eutectic areas. IGC was attributed to the network distribution of β phase along the grain boundaries, the depleted aluminium in the precipitation areas and the breakdown potential.

    17. Influence of sub-rapid solidification on microstructure and mechanical properties of AZ61A magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      The microstructure of sub-rapid solidification processed AZ61A magnesium alloy was presented and discussed. The results show that the grain size of the foil is significantly refined, and the grain morphology is cellular or globular. The eutectic transformation L→α-Mg+β-Mg17Al12 and microsegregation in conventionally solidified AZ61A alloy are suppressed to a great extent.The β-Mg17Al12 phases located in the α-Mg grain boundaries are largely decreased due to high solidification cooling rate. As a consequence, the alloying elements Al, Zn, Mn show much higher solid solubility and the sub-rapid solidification microstructure dominantly consists of supersaturated α-Mg solid solution. The mechanical properties and fractographic analysis reveal that the fracture mechanism and corresponding morphology of the rapture surface of tensile bars are linked to the microstructure obtained and depend on the sub-solidification processes.

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

      Energy Technology Data Exchange (ETDEWEB)

      Mohedano, M.; Arrabal, R.; Pardo, A.; Paucar, A.; Merino, M. C.; Matykina, E.; Mingo, B.; Garces, G.

      2014-04-01

      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 Al{sub 2}Nd/Al{sub 2}Gd and Al-Mn-Nd/Al-Mn-Gd intermetallics, reduced area fraction of {beta}-Mg{sub 1}7Al{sub 1}2 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. (Author)

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

      Science.gov (United States)

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

      2010-06-01

      In this paper, a constitutive framework based on a crystalline plasticity model is employed to simulate the plastic deformation of AZ31 magnesium alloy, which posses the hexagonal close packed (HCP) crystal structure. Dislocation slip and mechanical twinning are taken into account in the model. The successive integration method is used to determine the active slip systems, and the contribution of twinning to the grain reorientation is treated by the PTR method. The FE model is introduced into ABAQUS/Explicit through a user material subroutine (VUMAT). Three deformation processes of AZ31 magnesium alloy, including tension, compression and a stamping process, are simulated with the present method. The simulation results are compared with experiment and those presented in the literature.

    20. Preparation of AZ91D magnesium alloy semi-solid billet by new strain induced melt activated method

      Institute of Scientific and Technical Information of China (English)

      JIANG Ju-fu; LUO Shou-jing; ZOU Jing-xiang

      2006-01-01

      New strain induced melt activated (new SIMA) method for preparing AZ91D magnesium alloy semi-solid billet is introduced by applying equal channel angular extrusion into strain induced step in SIMA method, by which semi-solid billet with fine spheroidal grains and average grain size of 18 μm can be prepared. Furthermore, average grain size of semi-solid billet is reduced with increasing extrusion pass of AZ91D magnesium alloy obtained in ECAE process. By using semi-solid billet prepared by new SIMA, thixoforged magazine plates component with high mechanical properties such as yield strength of 201.4 MPa, ultimate tensile strength of 321.8 MPa and elongation of 15.3%, can be obtained.

    1. EFFECT OF PREDEFORMATION MANNER ON SEMI-SOLID STRUCTURE OF AZ61 MAGNESIUM ALLOY IN SIMA PROCESS

      Institute of Scientific and Technical Information of China (English)

      G.P.Chen; T.R.Zhou; H.Yan; F.Y.Zhang

      2008-01-01

      The effect of predecformation manner, predeformation ratio and isothermal heat-treat parameter on the non-dendrite structure of AZ61 magnesium alloy in SIMA process was studied. Under coequal heat-treat condition, the impact of the hot upsetting predeformation on semi-solid microstructure in SIMA process was compared with that of the cold compressive predeformation. The results indicate that non-dendrite microstructure in AZ61 magnesium alloy billets can be obtained by hot or cold upsetting predeformation in SIMA process, although their mechanisms of evolution are different.Increasing hot or cold upsetting predeformation ratio can enhance the effect and quality of the non-dendrite microstructure formed before storage energy up to saturation,but the proper isothermal temperature and holding time should be selected.

    2. Deposition of electroless Ni-P/Ni-W-P duplex coatings on AZ91D magnesium alloy

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      The electroless Ni-P/Ni-W-P duplex coatings were deposited directly on AZ91D magnesium alloy by all acid-sulfate nickel bath.Nickel suitIhate and sodium tungstate were used as metal ion sources and sodium hypophosphite was used as reducing agent.The coating was characterized for its structure,morphologies,microhardness and corrosion properties.The presence of dense and coarse nodules in the duplex coatings Was observed by SEM and EDS.Tungsten content in Ni-P/Ni-W-P alloy is about 0.65%(mass fraction)and the phosphorus content is 8.1 8%(mass fraction).The microhardness of the coatings is 622 VHN.The coating shows good adhesion to the substrate.The results of electrochemical analysis,the porosity and the immersion test show that Ni-P/Ni-W-P duplex coatings possess noble anticorrosion properties to protect the AZ91D magnesium alloy.

    3. Microstructure of Cu-based Amorphous Composite Coatings on AZ91D Magnesium Alloy by Laser Cladding

      Institute of Scientific and Technical Information of China (English)

      Kaijin Huang; Changsheng Xie; T.M.Yue

      2009-01-01

      To improve the sliding wear resistance of AZ91D magnesium alloy, Cu-based amorphous composite coatings made of Cu47Ti34Zr11Ni8 and Cu47Ti34Zr11Ni8+20 wt pct SiC powders were fabricated on AZ91D magnesium alloy by laser cladding, respectively. SEM (scanning electron microscopy), EDS (energy dispersive X-ray spectroscopy), XRD (X-ray diffraction) and TEM (transmission electron microscopy) techniques were employed to study the phases of the coatings. The results show that the coatings mainly consist of amorphous phase and different intermetallic compounds. The reason of formation of amorphous phase and the function of SiC particles were explained in details.

    4. Uniformity and continuity of effective strain in AZ91D processed by multi-pass equal channel angular extrusion

      Institute of Scientific and Technical Information of China (English)

      ZHANG Xiao-hua; LUO Shou-jing; DU Zhi-ming

      2008-01-01

      AZ91D magnesium alloy was processed by equal channel angular extrusion(ECAE). The influence of extrusion temperature, extrusion pass and extrusion route on the ultimate strength of the extruded billet was analyzed. The process of multi-pass extrusion was simulated with the method of finite element analysis, and the continuity and uniformity of effective strain in multi-pass extrusion were investigated. The results show that extrusion pass plays the most important role in improving the ultimate strength of AZ91D magnesium alloy, the extrusion route is the second, and the extrusion temperature is the last. From the numerical simulation, there exists the continuity of the accumulated deformation in multi-pass extrusion and the effective strain increases linearly. The tendency of the strain uniformity is different in multi-pass extrusion with extrusion routes. The results of experiment agree with those of numerical simulation.

    5. Initial corrosion behavior of AZ91 magnesium alloy in simulating acid rain under wet-dry cyclic condition

      Institute of Scientific and Technical Information of China (English)

      2008-01-01

      Corrosion behavior of AZ91 magnesium alloy in simulating acid rain under wet-dry cyclic condition was investigated.The results show that corrosion potential shifts positively and the corrosion current density decreases at low wet-dry cyclic time.Further increase of the cyclic time results in the negative movement of corrosion potential and the increase of current density.SEM observation indicates that corrosion Occurs only in αphase,βphase is inert in corrosive medium,and the corrosion of AZ91 magnesium appears in uniform characteristic.XPS analysis suggests that the corrosion product is mainly composed of oxide and hydroxide of magnesium and aluminum,and a small amount of sulfate is also contained in the film.

    6. Flow Stress and Mathematical Model for DRX Evolution of Semi-continuous Cast AZ80 Alloy During Hot Deformation

      Directory of Open Access Journals (Sweden)

      Liang Haicheng

      2016-01-01

      Full Text Available Using electromagnetic fields application ways, AZ80 magnesium alloy is semi-continuously cast into billets with diameter of 165 mm. And the dynamic recrystallization (DRX evolution of the semi-continuous cast AZ80 magnesium alloy during hot compression has been experimentally studied on Gleeble 2000 thermal-mechanical simulator, at temperatures from 260 to 410 °C and strain rates from 0.001 to 10s-1. It is found that the chief microstructure evolution is dynamic recrystallization, and the effect of deformation process parameters on DRX evolution is analyzed. The mathematical models including critical recrystallization model, kinetics model and grain size model of DRX are established and the results show good agreement between experiments and the models.

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

      OpenAIRE

      Noé Aguilar Rivera; Guadalupe Galindo Mendoza; Javier Fortanelli Martínez; Carlos Contreras Servín

      2011-01-01

      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 a...

    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. 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.

    10. 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.

    11. 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.

    12. 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.

    13. Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditions

      Directory of Open Access Journals (Sweden)

      V. Anes

      2014-10-01

      Full Text Available Components and structures are designed based in their material’s mechanical properties such as Young's modulus or yield stress among others. Often those properties are obtained under monotonic mechanical tests but rarely under cyclic ones. It is assumed that those properties are maintained during the material fatigue life. However, under cyclic loadings, materials tend to change their mechanical properties, which can improve their strength (material hardening or degrade their mechanical capabilities (material softening or even a mix of both. This type of material behaviour is the so-called cyclic plasticity that is dependent of several factors such as the load type, load level, and microstructure. This subject is of most importance in design of structures and components against fatigue failures in particular in the case of magnesium alloys. Magnesium alloys due to their hexagonal compact microstructure have only 3 slip planes plus 1 twining plane which results in a peculiar mechanical behaviour under cyclic loading conditions especially under multiaxial loadings. Therefore, it is necessary to have a cyclic elastic-plastic model that allows estimating the material mechanical properties for a certain stress level and loading type. In this paper it is discussed several aspects of the magnesium alloys cyclic properties under uniaxial and multiaxial loading conditions at several stress levels taking into account experimental data. A series of fatigue tests under strain control were performed in hour glass specimens test made of a magnesium alloy, AZ31BF. The strain/stress relation for uniaxial loadings, axial and shear was experimentally obtained and compared with the estimations obtained from the theoretical elastic-plastic models found in the state-of-the-art. Results show that the AZ31BF magnesium alloy has a peculiar mechanical behaviour, which is quite different from the steel one. Moreover, the state of the art cyclic models do not capture in

    14. Influence of heat treatment on microstructure of hot extruded AZ31

      Energy Technology Data Exchange (ETDEWEB)

      Dzwonczyk, J.; Bohlen, J.; Hort, N.; Kainer, K.U. [Inst. for Materials Research, Center for Magnesium Technology, GKSS Research Center (Germany)

      2003-07-01

      In the last years magnesium alloys have been increasingly considered as attractive materials for the transportation industry. Extruded magnesium alloys have been found in the centre of interest combining their lightweight, surface quality with the wide range of possible achievable geometries. In the present study the alloy AZ31 has been chosen for investigation as one of the most common commercial magnesium wrought alloys. Round bars have been obtained through hot direct extrusion. After primary microstructural characterisation and mechanical testing in the as-extruded condition the specimens have been subjected to heat treatment consisting of different times (1, 2 and 4 hours) at different temperatures (200 C, 300 C, 400 C and 500 C) followed by cooling in air. Subsequently the specimens have been subjected to microstructural characterisation using light optical microscopy. Average grain size and grain size distribution have been determined using dedicated software. The microstructural analysis has been supported by microhardness testing on selected specimens. Additionally, the specimens have been subjected to tensile tests at room temperature applying a deformation rate of 1.3 x 10{sup -4} s{sup -1} as used for the material in as-extruded conditions. The obtained results have shown that heat treatment has no substantial influence on the microstructure characteristics of AZ31 up to 400 C. However, specimens treated at 500 C for one hour revealed a course grain, homogeneous structure with a substantial increase in grain size from 8 {mu}m in as-extruded condition to 18 {mu}m. This change in microstructure slightly reduced the strain-hardening exponent from 0.2 to 0.16. The remaining mechanical properties did not vary extensively when compared to the untreated, as-extruded material. It is assumed that the average grain size and grain size distribution have been influenced by complex thermomechanical treatments, which occurred during extrusion process as well as

    15. Cold Metal Transfer joining of magnesium AZ31B-to-aluminum A6061-T6

      Energy Technology Data Exchange (ETDEWEB)

      Cao, R., E-mail: caorui@lut.cn [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China); Wen, B.F. [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China); Chen, J.H., E-mail: zchen@lut.cn [State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050 (China); Wang, Pei-Chung [Manufacturing Systems Research Lab General Motors (United States)

      2013-01-10

      Automotive manufacturers are faced with increasing pressure to reduce vehicle weight, improve fuel economy, reduce emissions, and enhance vehicle safety and performance. Therefore, an increasing number of vehicle structures are built using a combination of dissimilar materials such as steel, aluminum and magnesium. Though the advantages are potentially huge, this hybrid fabrication approach raises substantial technical challenges to the design of vehicle structures and the associated joining processes. Once two elements (e.g., magnesium-aluminum, aluminum-steel) are mixed in a high temperature welding pool, brittle intermetallic phases (IMP) can be easily formed. Experimental observations showed that a series of intermetallic phases will greatly reduce the mechanical performance of the welded dissimilar materials. In this study, welding of 1 mm thick magnesium AZ31B-to-1 mm thick aluminum A6061-T6 using a 1.6 mm diameter aluminum filler wire 4047 was investigated. Cold Metal Transfer (CMT) arc welding technique was adopted. The key feature of this process is that the motion of the wire has been integrated into the overall control of the process. The wire retraction motion assists droplet detachment during the short circuit, thus the metal can transfer into the welding pool without the aid of the electromagnetic force. In this way the heat input and spatter can be controlled and the IMP formation minimized thereby improving the joint strength. Extensive experiments were performed and analyzed. It was found that although extensive efforts have been exercised to control the heat input, Mg-rich intermetallic {gamma}-Al{sub 12}Mg{sub 17} and Al-rich intermetallic {beta}-Al{sub 3}Mg{sub 2} were still produced in the weld. Fracture surfaces of CMT welded AZ31B-Al6061-T6 joints exhibited the Mg-rich intermetallic ({gamma}-Al{sub 12}Mg{sub 17}) which contributes to the weld strength degradation. To improve the joint, minimizing the content of the intermetallics especially

    16. Superplastic behaviour of AZ91 magnesium alloy processed by high-pressure torsion

      Energy Technology Data Exchange (ETDEWEB)

      Al-Zubaydi, Ahmed S.J., E-mail: asaz1e11@soton.ac.uk [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Branch of Materials Science, Department of Applied Sciences, University of Technology, Baghdad (Iraq); Zhilyaev, Alexander P. [Institute for Problems of Metals Superplasticity, Russian Academy of Sciences, Khalturina 39, Ufa 450001 (Russian Federation); Wang, Shun C.; Reed, Philippa A.S. [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom)

      2015-06-18

      An investigation has been conducted on the tensile properties of a fine-grained AZ91 magnesium alloy processed at room temperature by high pressure torsion (HPT). Tensile testing was carried out at 423 K, 473 K and 573 K using strain rates from 1×10{sup −1} s{sup −1} to 1×10{sup −4} s{sup −1} for samples processed in HPT for N=1, 3, 5 and 10 turns. After testing was completed, the microstructures were investigated by scanning electron microscopy and energy dispersive spectroscopy. The alloy processed at room temperature in HPT exhibited excellent superplastic behaviour with elongations higher than elongations reported previously for fine-grained AZ91 alloy produced by other severe plastic deformation processes, e.g. HPT, ECAP and EX-ECAP. A maximum elongation of 1308% was achieved at a testing temperature of 573 K using a strain rate of 1×10{sup −4} s{sup −1}, which is the highest value of elongation reported to date in this alloy. Excellent high-strain rate superplasticity (HSRSP) was achieved with maximum elongations of 590% and 860% at temperatures of 473 K and 573 K, respectively, using a strain rate of 1×10{sup −2} s{sup −1}. The alloy exhibited low-temperature superplasticity (LTSP) with maximum elongations of 660% and 760% at a temperature of 423 K and using strain rates of 1×10{sup −3} s{sup −1} and 1×10{sup −4} s{sup −1}, respectively. Grain-boundary sliding (GBS) was identified as the deformation mechanism during HSRSP, and the glide-dislocation creep accommodated by GBS dominated during LTSP. Grain-boundary sliding accommodated with diffusion creep was the deformation mechanism at high test temperature and slow strain rates. An enhanced thermal stability of the microstructure consisting of fine equiaxed grains during deformation at elevated temperature was attributed to the extremely fine grains produced in HPT at room temperature, a high volume fraction of nano β-particles, and the formation of β-phase filaments.

    17. 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.

    18. Corrosion mechanism of micro-arc oxidation treated biocompatible AZ31 magnesium alloy in simulated body fluid

      OpenAIRE

      Ying Li; Fang Lu; Honglong Li; Wenjun Zhu; Haobo Pan; Guoxin Tan; Yonghua Lao; Chengyun Ning; Guoxin Ni

      2014-01-01

      The rapid degradation of magnesium (Mg) based alloys has prevented their further use in orthopedic trauma fixation and vascular intervention, and therefore it is essential to investigate the corrosion mechanism for improving the corrosion resistance of these alloys. In this work, the effect of applied voltage on the surface morphology and the corrosion behavior of micro-arc oxidation (MAO) with different voltages were carried out to obtain biocompatible ceramic coatings on AZ31 Mg alloy. The ...

    19. Hernán Cortés’ Tears in the Historia verdadera by Bernal Díaz del Castillo

      OpenAIRE

      Fernando Rodriguez Mansilla

      2016-01-01

      This article analyzes the function of Hernán Cortés’ tears in the Historia verdadera by Bernal Díaz del Castillo. Some critics have read Cortés’ weeping as a sign of weakness. Actually, the tears of the hero are a manifestation that links the figure of the conqueror —and by extension the whole text— to the classical epic tradition, as well as to an incipient concept of tragedy.

    20. Hernán Cortés’ Tears in the Historia verdadera by Bernal Díaz del Castillo

      Directory of Open Access Journals (Sweden)

      Fernando Rodriguez Mansilla

      2016-05-01

      Full Text Available This article analyzes the function of Hernán Cortés’ tears in the Historia verdadera by Bernal Díaz del Castillo. Some critics have read Cortés’ weeping as a sign of weakness. Actually, the tears of the hero are a manifestation that links the figure of the conqueror —and by extension the whole text— to the classical epic tradition, as well as to an incipient concept of tragedy.