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1

Hiperfenilalaninemia por deficiência de fenilalanina hidroxilase : avaliação da responsividade ao BH4 em pacientes acompanhados no Serviço de Genética Médica do HCPA e que apresentam controle metabólico adequado.  

E-print Network

??Introdução: Estudos recentes, utilizando vários protocolos, têm demonstrado que pacientes com Hiperfenilalaninemia por deficiência de fenilalanina hidroxilase (HPA-PAH) podem apresentar redução das concentrações plasmáticas de… (more)

Tatiéle Nalin

2011-01-01

2

Prevalencia de disfunción eyaculatoria secundaria al tratamiento con alfa-bloqueantes en pacientes con hiperplasia benigna de próstata  

Microsoft Academic Search

PREVALENCE OF EJACULATORY DYSFUNCTION SECONDARY TO ALPHA-BLOCKER THERAPY IN PATIENTS WITH BENIGN PROSTATIC HYPERPLASIA Introduction: Benign prostatic hyperplasia (BPH) is characterized by lower urinary tract symptoms (LUTS) that may cause ejaculatory disorders, although they could be also a consequence of alpha-blocker treatment. Objectives: To determine the prevalence of ejaculatory dysfunction in patients with HBP undergoing alpha-blocker therapy. Secondary objectives were

A. Martín-Morales; G. Meyer; E. Ramírez

2008-01-01

3

Evaluación económica del tratamiento médico de la hiperplasia benigna de próstata (HBP) en España en atención especializada: Aplicación al coste-efectividad de dos fármacos habitualmente utilizados en su tratamiento  

Microsoft Academic Search

ECONOMIC EVALUATION OF MEDICAL TREATMENT OF BENIGN PROSTATIC HYPERPLASIA (BPH) IN THE SPECIALISED CARE SET- TING IN SPAIN. APPLICATION TO THE COST-EFFECTIVENESS OF TWO DRUGS FREQUENTLY USED IN ITS TREATMENT Objectives: To develop a pharmacoeconomic study in order to know the average cost of BPH diagnosis and follow-up in Spain in the Urology Department setting from the perspective of the

J. Carballido; J. L. Ruiz-Cerdá; M. Unda; V. Baena; P. Campoy; J. Manasanch; J. Slof

2008-01-01

4

Strong et al ALS FTD consensus criteria  

E-print Network

Strong et al ALS FTD consensus criteria 1 Version: 20070606 Frontotemporal syndromes in amyotrophic-663-3609 Email: mstrong@uwo.ca #12;Strong et al ALS FTD consensus criteria 2 Introduction Although amyotrophic

Dickerson, Brad

5

Al Composites  

NASA Astrophysics Data System (ADS)

In the present study, cold spraying technique was used to fabricate a metal matrix composite (MMC) that consists of Ni matrix and 20 vol.% Ni3Al particles at two different particle sizes as reinforcement. This study intends to investigate the effect of reinforcement particle size on microstructural and mechanical properties of cold sprayed MMCs. Two different Ni3Al powders with nominal particle size of -45 to +5 and +45 to 100 ?m were used as reinforcement in this study. Cold sprayed Ni-Ni3Al samples were subjected to the microstructural observation and characterization prior to any mechanical testing. Then, samples were tested using nano-indentation, Knoop hardness, Vickers hardness, and Resonance frequency to evaluate their mechanical properties. No significant changes were observed in microstructural characteristics due to different particle sizes. The results obtained from a variety of mechanical testings indicated that the increasing reinforcement particle size resulted in the slight reduction of mechanical properties such as elastic modulus and hardness in cold sprayed MMCs. The mechanical interlock between deposited particles defines the bonding strength in cold sprayed samples. Small size particles have a higher velocity and impact resulting in stronger interlock between deformed particles.

Chandanayaka, Tharaka; Azarmi, Fardad

2014-05-01

6

Amyotrophic Lateral Sclerosis (ALS)  

MedlinePLUS Videos and Cool Tools

Amyotrophic Lateral Sclerosis Introduction Amyotrophic Lateral Sclerosis, or ALS, is a serious neurological disease that affects the ability to ... com nr180104 Last reviewed: 03/20/2013 1 ALS ALS attacks the neurons that control muscles, the ...

7

About ALS: FAQ  

MedlinePLUS

... are the potential side effects? What Is ALS? Amyotrophic Lateral Sclerosis (ALS) is a motor neuron disease, first identified in ... neurologist Jean-Martin Charcot. Although the cause of ALS is not completely understood, recent years have brought ...

8

Amyotrophic Lateral Sclerosis (ALS)  

MedlinePLUS

NINDS Amyotrophic Lateral Sclerosis (ALS) Information Page Clinical Trials Natural History and Biomarkers of C9ORF72 ALS and FTD The ... Trials Organizations Additional resources from MedlinePlus What is Amyotrophic Lateral Sclerosis (ALS)? Amyotrophic lateral sclerosis (ALS), sometimes ...

9

/Cu-Al System  

NASA Astrophysics Data System (ADS)

Wettability and interfacial interaction of the Ta2O5/Cu-Al system were studied. Pure Cu does not wet the Ta2O5 substrate, and improved spreading is achieved when relatively a high fraction of the active element (~40 at.% Al) was added. The Al2O3 and AlTaO4 phases were observed at the Ta2O5/Cu-Al interface. A thermodynamic evaluation allowed us to suggest that the lack of wetting bellow 40 at.% Al is due to the presence of a native oxide, which covers the drop. The conditions of the native oxide decomposition and the formation of the volatile Al2O suboxide strongly depend on the vacuum level during sessile drop experiments and the composition of the Cu-Al alloy. In our case, Al contents greater than 40% provides thermodynamic conditions for the formation of Al2O (as a result of Al reaction with Al2O3) and the drop spreading. It was suggested that the final contact angle in the Ta2O5/Cu-Al system (50°) is determined by Ta adsorption on the newly formed alumina interlayer.

Kish, Orel; Froumin, Natalya; Aizenshtein, Michael; Frage, Nachum

2014-05-01

10

Amyotrophic Lateral Sclerosis (ALS)  

Microsoft Academic Search

ALS, commonly called Lou Gehrig's disease, is a devastating neurological dis- order characterized by selective upper and lower somatic, but not autonomic, motor neurone degeneration leading to paralysis and eventually death. The diagnosis of ALS requires the presence of both upper and lower motor neu- rone degeneration and progressive motor dysfunction. ALS occurs in 1 to 2.5 cases per 100,000

Chris G. Parsons; Wojciech Danysz

11

ALS: AN ETHICAL PERSPECTIVE  

Microsoft Academic Search

Amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, is a relentlessly progressive, fatal and presently incurable motor neuron disorder caused by degeneration of both upper and lower neurons that control voluntary skeletal muscle. ALS variants include a progressive lower motor neuron disorder, Progressive Muscular Atrophy (PMA); a progressive upper motor neuron disorder, Primary Lateral Sclerosis (PLS); and a progressive disorder

Leo McCluskey

12

[Environmental factors in ALS].  

PubMed

ALS is likely to be a disorder of multifactorial origin. Among all the factors that may increase the risk of ALS, environmental ones are being studied for many years, but in the recent years, several advances have pointed to a new interest in their potential involvement in the disease process, especially for the cyanotoxin BMAA. Food containing BMAA has been found on Guam, a well-known focus of ALS/parkinsonism/dementia and high levels of BMAA have been identified into the brain of these patients. The BMAA cyanotoxin is potentially ubiquitous and have also been found into the food of patients who died from ALS both in Europe and USA. BMAA can be wrongly integrated into the protein structure during mRNA traduction, competing with serine. This may induce abnormal protein folding and a subsequent cell death. Heavy metals, such as lead or mercury may be directly toxic for neuronal cells. Several works have suggested an increased risk of ALS in individuals chronically exposed to these metals. Exposure to pesticides has been suggested to be linked to an increased risk of developing ALS. The mechanism of their toxicity is likely to be mediated by paraoxonases. These proteins are in charge of detoxifying the organism from toxins, and particularly organophosphates. To date, there are insufficient scientific data to suggest that exposure to electromagnetic fields may increase the risk of having ALS. We are particularly missing longitudinal cohorts to demonstrate that risk. PMID:24703731

Juntas-Morales, Raul; Pageot, Nicolas; Corcia, Philippe; Camu, William

2014-05-01

13

Primary AL Amyloidosis  

MedlinePLUS

... AL amyloidosis is a hematological disorder, associated with plasma cell dyscrasia that means an abnormal condition of ... fibrils, formed by an errant (monoclonal) group of plasma cells in the bone marrow, consist of abnormal ...

14

Malnutrition in ALS  

MedlinePLUS

... weakened tongue can make it difficult to swallow. Anorexia and depression may also contribute to the patient’s ... difficulty swallowing and/or breathing, constipation, pressure sores, anorexia, fatigue, spasms and confusion. ALS patients particularly susceptible ...

15

Advanced aerospace Al alloys  

Microsoft Academic Search

SiC particulate or whisker-reinforced aluminum alloys are very attractive for applications requiring high stiffness coupled with a comparatively light weight. The dispersion strengthened Al alloys produced through the rapid solidification processing\\/powder metallurgy route demonstrate superior elevated temperature strength and microstructural stability, extending the useful service temperature of Al alloys to 350 C. However, low ductility and poor fracture toughness levels

K. S. Ravichandran; E. S. Dwarakadasa

1987-01-01

16

ALS superbend magnet performance  

SciTech Connect

The Lawrence Berkeley National Laboratory has been engaged in the design, construction and testing of four superconducting dipoles (Superbends) that are installed in three arcs of the Advanced Light Source (ALS), with the fourth magnet as a spare. This represents a major upgrade to the ALS providing an enhanced flux and brightness at photon energies above 10 keV. In preparation for installation, an extensive set of tests and measurements have been conducted to characterize the magnetic and cryogenic performance of the Superbends and to fiducialize them for accurate placement in the ALS storage ring. The magnets are currently installed, and the storage ring is undergoing final commissioning. This paper will present the results of magnetic and cryogenic testing.

Marks, Steve; Zbasnik, John; Byrne, Warren; Calais, Dennis; Chin, Michael; DeMarco, Richard; Fahmie, Michael; Geyer, Alan; Krupnick, Jim; Ottens, Fred; Paterson, James A.; Pipersky, Paul; Robin, David S.; Schlueter, RossD.; Steier, Christoph; Wandesforde, Alan

2001-12-10

17

Rapidly solidified NiAl and FeAl  

NASA Technical Reports Server (NTRS)

Melt spinning was used to produce rapidly solidified ribbons of the B2 intermetallics NiAl and FeAl. Both Fe-40Al and Fe-45Al possessed some bend ductility in the as spun condition. The bend ductility of Fe-40Al, Fe-45Al, and equiatomic NiAl increased with subsequent heat treatment. Heat treatment at approximately 0.85 T (sub m) resulted in significant grain growth in equiatomic FeAl and in all the NiAl compositions. Low bend ductility in both FeAl and NiAl generally coincided with intergranular failure, while increased bend ductility was characterized by increasing amounts of transgranular cleavage fracture.

Gaydosh, D. J.; Crimp, M. A.

1984-01-01

18

Al Qaeda Training Manual  

NSDL National Science Digital Library

The first resource is a US Department of Justice release of portions of an English translation of the Al Qaeda training manual located by police in Manchester, England during a search of an Al Qaeda member's home. The manual was found in a computer file described as "the military series" related to the "Declaration of Jihad." The cover and excerpts from the 12 chapters can be viewed as a .pdf file. Content of the text includes religious commentary, organizational tactics, guidelines for member selection, techniques for spying, and security measures. The DOJ does not provide the entire document because it does not want to encourage terrorism.

2001-01-01

19

Al Shanker Remembers.  

ERIC Educational Resources Information Center

In a 1996 interview shortly before his death, Al Shanker, longtime president of the American Federation of Teachers, discussed such topics as: his own educational experiences; how he learned about political fighting in the Boy Scouts; the appeal of socialism; multinational corporations and the nation state; teaching tough students; and John Dewey…

American Educator, 2000

2000-01-01

20

Smith et al Supporting Information  

E-print Network

Smith et al 1 Supporting Information for Smith et al. 2006, PLoS Computational Biology 2:e161-hyperpallium apicale; HF-hippocampal formation, and M-mesopallium. #12;Smith et al 2 FigureS2,nolinkswerefoundbetweenelectrodesindifferentbirds,andnolinkswerefoundintothesoundstimulusvariable. CombinedAnalysisofAllBirds'ElectrodesPlusSound #12;Smith et al 3 Analysis of Data from Subsections

Jarvis, Erich D.

21

/Al-Si Composite  

NASA Astrophysics Data System (ADS)

The cyclic fatigue characteristics of spray-deposited SiCp/Al-Si composite were investigated in comparison with the unreinforced Al-Si alloy. The as-extruded specimens were cyclically deformed with fully reversed loading under a range of total strain amplitudes. The results show that the cyclic response characteristics for the reinforced and unreinforced materials are similar to each other. Both the composite and matrix alloys display cyclic hardening under total strain amplitude of 0.35-0.5%. Otherwise, the composite exhibits higher degree of strain hardening than that of the matrix alloy. Dislocation substructure developed during cyclic deformation was analyzed using transmission electron microscopy. The discrepancy between dislocation substructures obtained from processing compared to its development during cyclic strain loading is thought to give rise to the observed cyclic stress response behavior. Fractographic analysis shows that particle/matrix debonding and particle cracking are the main mechanisms of failure in the SiC particle-reinforced composite.

Li, Wei; Chen, Jian; Hu, Yongle; Cong, Li; Sun, YouPing; Yang, JiMing

2014-08-01

22

Al Parker: American Illustrator  

NSDL National Science Digital Library

This tribute to Al Parker, the noted magazine illustrator and artist, was fashioned from extensive holdings at the Washington University Library in St. Louis. Known as "The Dean of Illustrators," Al Parker attended school at the St. Louis School of Fine Arts at Washington University and went on to become of the most prolific and important American illustrators of the twentieth century. Parker was best-known for his modernist deployment of line, patterning, and bold, flat colors, which helped shape the general "look" of the period from the 1930s to the 1960s. Using short clips of Parker's original illustrations and drawings, this exhibit offers a glimpse into his work and contributions to the medium. Of particular interest is the section devoted to Parker's famous "Mother-Daughter" covers for the Ladies Home Journal, which began in 1939 and ran for 17 years.

2001-01-01

23

ALS Project Management Manual  

SciTech Connect

This manual has been prepared to help establish a consistent baseline of management practices across all ALS projects. It describes the initial process of planning a project, with a specific focus on the production of a formal project plan. We feel that the primary weakness in ALS project management efforts to date stems from a failure to appreciate the importance of ''up-front'' project planning. In this document, we present a guide (with examples) to preparing the documents necessary to properly plan, monitor, and control a project's activities. While following the manual will certainly not guarantee good project management, failure to address the issues we raise will dramatically reduce the chance of success. Here we define success as meeting the technical goals on schedule and within the prescribed budget.

Krupnick, Jim; Harkins, Joe

2000-05-01

24

Partnerwahl als konsensuelle Entscheidung  

Microsoft Academic Search

Zusammenfassung  Die vorliegende Studie setzt unsere Analysen der Kontaktierungsprozesse im Online-Dating (KZfSS 2\\/2009) fort. Da Paarbeziehungen\\u000a auf einer konsensuellen Entscheidung für eine gemeinsame Beziehung beruhen, widmet sich der vorliegende Beitrag der Frage,\\u000a wie Männer und Frauen auf Erstkontaktversuche reagieren. Die Datenstruktur von Online-Dating-Börsen bietet eine einzigartige\\u000a Chance, soziologisch im Detail zu rekonstruieren, wie Paarbeziehungen als konsensuelle Wahlhandlung nach und nach entstehen.

Florian Schulz; Jan Skopek; Hans-Peter Blossfeld

2010-01-01

25

Abu Musab Al Suri: Architect of the New Al Qaeda  

Microsoft Academic Search

Drawing on new sources, the authors argue that Abu Musab al Suri (real name Mustafa Setmariam Nasar), now in U.S. custody, is the principle architect of Al Qaeda's post–9\\/11 structure and strategy. His vision, which predated 9\\/11, of transforming Al Qaeda from a vulnerable hierarchical organization into a resilient decentralized movement, was largely the formula Al Qaeda adopted after the

Paul Cruickshank; Mohannad Hage Ali

2007-01-01

26

THARYAN ET AL'S REPLY  

E-print Network

The comment by Dr. Andrade raising the possibility of missed subclinical fractures as a complication of unmodified ECT in some patients in our study is valid as patients were investigated radiographically only on clinical indication. Ihe aim of the study, however, was to survey the frequency of clinically significant physical complications. Crush fractures of the vertebrae, whether overt or covert, caused during unmodified electrconvulsivc therapy are clinically of little significance. They were frequently overlooked in the early years after the introduction of convulsive therapy as they were often painless or only caused transient pain that was often mistaken for myalgia. There were also no sequelae and no treatment was required (Kiloh et al,

unknown authors

27

Al Jazirah, Sudan  

NASA Technical Reports Server (NTRS)

Al Jazirah (also Gezira) is one of the 26 states of Sudan. The state lies between the Blue Nile and the White Nile in the east-central region of the country. It is a well populated area suitable for agriculture. The area was at the southern end of Nubia and little is known about its ancient history and only limited archaeological work has been conducted in this area. The region has benefited from the Gezira Scheme, a program to foster cotton farming begun in 1925. At that time the Sennar Dam and numerous irrigation canals were built. Al Jazirah became the Sudan's major agricultural region with more than 2.5 million acres (10,000 km) under cultivation. The initial development project was semi-private, but the government nationalized it in 1950. Cotton production increased in the 1970s but by the 1990s increased wheat production has supplanted a third of the land formerly seeded with cotton.

The image was acquired December 25, 2006, covers an area of 56 x 36.4 km, and is located near 14.5 degrees north latitude, 33.1 degrees east longitude.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

2008-01-01

28

Submicron Nb-Al/Al oxide-Nb tunnel junctions sandwiched between Al films  

NASA Astrophysics Data System (ADS)

A process has been developed to embed Nb-Al/Al oxide-Nb junctions in planar structures of Al films. The submicron junctions are defined by photoresist lines. Motivation for this effort is a possible application of Nb junctions confined between normal conducting Al films as mixers above 700 GHz where Nb films loose their superconductive properties and tuning circuits made out of Nb therefore exhibit losses. First mixer results at 816 GHz are presented.

Maier, D.; Rothermel, H.; Gundlach, K. H.; Zimmermann, R.

1996-02-01

29

Microstructure and Mechanical Properties of HoAl-Al2O3\\/Ti Al Composite  

Microsoft Academic Search

HoAl-Al2O3\\/TiAl composites were fabricated by in-situ reaction synthesis using Al, Ti, TiO2 and Ho2O3 powders as raw materials. The effects of Ho2O3 content on the microstructure and mechanical properties of the composites were investigated. The phase constitution and microstructure of the composites were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results indicate that the ultimate phases

Hongya Xu; Fen Wang; Jianfeng Zhu; Yuxing Xie

2011-01-01

30

Descenso al Infierno de VenusDescenso al Infierno de VenusDescenso al Infierno de VenusDescenso al Infierno de Venus Manuel Alfonseca  

E-print Network

Descenso al Infierno de VenusDescenso al Infierno de VenusDescenso al Infierno de VenusDescenso al Infierno de Venus Manuel Alfonseca #12;Manuel Alfonseca 2 #12;Descenso al infierno de Venus 3 Descenso al infierno de Venus Manuel Alfonseca RESERVADOS TODOS LOS DERECHOS. Salvo usos razonables destinados al

Alfonseca, Manuel

31

Alexandria (Al Iskandariya), Egypt  

NASA Technical Reports Server (NTRS)

This image of Alexandria was taken by astronauts on board the International Space Station in December 2000 using an Electronic Still Camera. A wider-angle view (STS088-739-90) taken from the Space Shuttle in December 1998 is available for context. Alexandria (Al Iskandariya) occupies a T-shaped peninsula and strip of land separating the Mediterranean from Lake Mariout. Originally the town was built upon a mole (stone breakwater) called Heptastadium, which joined the island of Pharos (see referenced website, below) to the mainland. Since then sedimentary deposits have widened the mole. Since 1905, when the 370,000 Alexandrians lived in an area of about 4 sq km between the two harbors, the city (population 4 million; see referenced website, below) has grown beyond its medieval walls and now occupies an area of about 300 sq km. The Mahmudiya Canal, connecting Alexandria with the Nile, runs to the south of the city and, by a series of locks, enters the harbor of the principal port of Egypt (note ships). The reddish and ochre polygons west of Lake Mariout are salt-evaporation, chemical-storage, and water-treatment ponds within the coastal lagoon. Reference Youssef Halim and Fatma Abou Shouk, 2000, Human impacts on Alexandria's marine environment: UNESCO, Coastal Regions and Small Islands Unit (CSI), Coastal Management Sourcebooks 2 (accessed December 20, 2000) Additional photographs taken by astronauts can be viewed at NASA-JSC's Gateway to Astronaut Photography of Earth. Image ISS001-ESC-5025 provided by the Earth Sciences and Image Analysis Laboratory, Johnson Space Center.

2002-01-01

32

Creencias asociadas a la hiperplasia prostÆtica benigna  

Microsoft Academic Search

The purpose of the research is to conduct a review on the rol of the beliefs associated to benign prostatic hyperplasia. Cognitive, behavioral and attitudinal aspects are evaluated related to irrational beliefs with relation to this illness whose prevalence is in the rise in male colombian population.

Stefano Vinaccia; Fanny Sierra; Mery Monsalve; Erika Janeth Cano

33

Al Qaeda's Scorecard: A Progress Report on Al Qaeda's Objectives  

Microsoft Academic Search

Terrorism scholars are divided over whether terrorism is an effective tactic. Disagreement derives from the fact that the objectives of terrorist groups are often highly contested. Nowhere is this clearer than in contemporary statements on Al Qaeda. This article explores the most common interpretations for why Al Qaeda attacked the United States on 11 September 2001, and then analyzes their

Max Abrahms

2006-01-01

34

Al Qaeda: Ideology and action  

Microsoft Academic Search

Serious threats to global order are said to emanate from Al Qaeda, exemplified by bombings and multiple deaths in, inter alia, Bali, Dar es Salaam, Istanbul, Nairobi, New York and Madrid. These outrages raise the question about the ideological assumptions and goals of Al Qaeda – given that the majority of the dead were not Jews or Christians, but Muslims. What

JEFFREY HAYNES

2005-01-01

35

How al Qaeda lost Iraq  

Microsoft Academic Search

Al Qaeda in Iraq (AQI) has suffered a grave setback in the context of its ongoing campaign there. Since late 2006 Sunni tribal militias working in conjunction with Coalition forces have decimated AQI's ranks, and the organisation has been largely expelled from its former sanctuaries in western Iraq. This article seeks to explain the causes of al Qaeda's defeat with

Andrew Phillips

2009-01-01

36

Thin Films Using Al Doping  

NASA Astrophysics Data System (ADS)

We have studied the influence of Al doping on the microstructural, optical, and electrical properties of spray-deposited WO3 thin films. XRD analyses confirm that all the films are of polycrystalline WO3 in nature, possessing monoclinic structure. EDX profiles of the Al-doped films show aluminum peaks implying incorporation of Al ions into WO3 lattice. On Al doping, the average crystallite size decreases due to increase in the density of nucleation centers at the time of film growth. The observed variation in the lattice parameter values on Al doping is attributed to the incorporation of Al ions into WO3 lattice. Enhancement in the direct optical band gap compared to the undoped film has been observed on Al doping due to decrease in the width of allowed energy states near the conduction band edge. The refractive indices of the films follow the Cauchy relation of normal dispersion. Electrical resistivity compared to the undoped film has been found to increase on Al doping.

Mukherjee, Ramnayan; Prajapati, C. S.; Sahay, P. P.

2014-09-01

37

Allegato "B" DOMANDA DI PARTECIPAZIONE AL CONCORSO DI AMMISSIONE AL  

E-print Network

IN ROBOTICA, NEUROSCIENZE, NANOTECNOLOGIE E SCOPERTA FARMACI IN COLLABORAZIONE CON LA FONDAZIONE IIT Si prega'ammissione al Corso di Dottorato di Ricerca in Robotica, Neuroscienze, Nanotecnologie e Scoperta Farmaci

Sandini, Giulio

38

[ALS and excitatory amino acid].  

PubMed

AMPA receptor, one of ionotropic glutamate receptors, has been proposed to play a critical role to initiate the neuronal death cascade in motor neuron disease by an increase of Ca2+ influx. There are at least two mechanisms to increase Ca2+ influx through Ca2+-permiable AMPA receptor: a decrease of RNA editing efficacy at the GluR2 Q/R site and a decrease of GluR2 level relative to AMPA receptor subunits. Deficient RNA editing of the AMPA receptor subunit GluR2 at the Q/R site is a primary cause of neuronal death and recently has been reported to be a tightly linked etiological cause of motor neuron death in sporadic amyotrophic lateral sclerosis (ALS). On the other hand, relative low GluR2 level among AMPA receptor subunits seems to increase Ca2+ permeability of motor neurons in familial ALS (ALS1) linked to mutated cupper-zinc superoxide dismutase gene (SOD1). AMPA receptor-mediated mechanism does not seem to play any role in death of motor neurons in X-linked spinal and bulbar muscular atrophy (SBMA). From the molecular pathomechanism of sporadic ALS and ALS1, drugs which increase RNA editing efficacy at the GluR2 Q/R site could be a potent therapy for sporadic ALS, while AMPA receptor antagonists could prevent deterioration from ALS1. PMID:17969352

Aizawa, Hitoshi; Kwak, Shin

2007-10-01

39

Synthesis, processing and characterization of NiAl-AlN-Al(2)O(3) composites  

NASA Astrophysics Data System (ADS)

A hybrid composite based on nickel aluminide (NiAl) was developed, which contains both aluminum nitride (AlN) dispersoids and short alumina (Alsb2Osb3) fibers, with the strategy being the combination of the two different strengthening mechanisms, one microscopic and the other macroscopic, to provide a synergistic improvement in the mechanical properties. The AlN dispersion strengthened NiAl was synthesized by mechanical alloying of nickel and aluminum elemental powders in a nitrogen atmosphere and the alumina fibers were added during consolidation. The microstructure of the NiAl-(AlN)sb{Dispersion}-(Alsb2Osb3)sb{Fiber} composites showed a fine grain sized, near-stoichiometric NiAl matrix, submicron size AlN particles and randomly oriented Alsb2Osb3 fibers dispersed homogeneously in the matrix. The thermal residual stresses in the composites were measured at room temperature as well as at high temperatures using neutron diffraction and Rietveld refinement. The residual stresses in the as-processed composites were tensile in the NiAl matrix and compressive in the AlN and Alsb2Osb3 reinforcements. Upon heating these stresses relaxed at temperatures that are lower than the processing temperature due to the creep in the matrix. A simple finite element analysis was used to estimate the residual stress in the composites and showed reasonable agreement with the experimental results. The compressive strength of these composites was characterized both at 300K and 1300K and showed a significant strengthening compared with the base material at both temperatures. The relationship between the microstructure, residual stress and the mechanical properties was studied and the strengthening mechanisms were identified.

Choo, Hahn

40

Modeling of the ALS linac  

SciTech Connect

The ALS injector linac is used for the Beam Test Facility (BTF) and the Damping Experiments when it is available in between the ALS filings. These experiments usually require higher quality beams and a better characterization than is normally required for ALS operations. This paper focuses on the beam emittance, energy tilt, and especially the longitudinal variation of the beam parameters. For instance, the authors want to avoid longitudinal variations at the low beta section of the BTF. On the other hand, a large energy tilt is required for post-acceleration compression of the bunch using an alpha magnet. The PARMELA code was modified to calculate and display longitudinal variations of the emittance ellipse. Using the Microsoft Development Studio under Windows NT environment the code can handle a much larger number of particles than was previously possible.

Kim, C.H. [Lawrence Berkeley Lab., CA (United States). Advanced Light Source Center

1996-08-01

41

-and -Coordinated Al in AlC2 . A Combined  

E-print Network

/Al/Si composite target, respectively, with a pure helium carrier gas, and detected by a time-of-flight mass energies: 355 (3.496 eV) and 266 nm (4.661 eV). Photoelectron time-of-flight spectra were measured neutral species. The experiments were carried out with a magnetic- bottle time-of-flight PES apparatus

Simons, Jack

42

Triple A syndrome mimicking ALS.  

PubMed

We report a 22-year-old female who presented with distal muscular atrophy and weakness in all limbs for two years. Reflexes were symmetrically brisk and electrodiagnostic studies were consistent with upper and lower motor neuron involvement. A diagnosis of juvenile ALS was considered. However, surgery for achalasia in childhood and identification of alacrima and adrenal insufficiency suggested Triple A syndrome accompanied by neurological symptoms. Sequencing of the AAAS gene identified compound heterozygous mutations confirming the clinical diagnosis and demonstrating that Triple A syndrome can mimic juvenile ALS. PMID:18615337

Strauss, Maria; Koehler, Katrin; Krumbholz, Manuela; Huebner, Angela; Zierz, Stephan; Deschauer, Marcus

2008-10-01

43

A nuclear magnetic resonance probe of Fe-Al and Al20V2Eu intermetallics  

E-print Network

Al-rich Fe-Al systems (FeAl2, Fe2 Al5 and Fe4Al13) and Al20V2Eu have complicated structures with quasicrystal-like features making these materials potentially of interest for magnetic behavior. However, there is not much work on these materials...

Chi, Ji

2009-05-15

44

Dynamic Modeling of ALS Systems  

NASA Technical Reports Server (NTRS)

The purpose of dynamic modeling and simulation of Advanced Life Support (ALS) systems is to help design them. Static steady state systems analysis provides basic information and is necessary to guide dynamic modeling, but static analysis is not sufficient to design and compare systems. ALS systems must respond to external input variations and internal off-nominal behavior. Buffer sizing, resupply scheduling, failure response, and control system design are aspects of dynamic system design. We develop two dynamic mass flow models and use them in simulations to evaluate systems issues, optimize designs, and make system design trades. One model is of nitrogen leakage in the space station, the other is of a waste processor failure in a regenerative life support system. Most systems analyses are concerned with optimizing the cost/benefit of a system at its nominal steady-state operating point. ALS analysis must go beyond the static steady state to include dynamic system design. All life support systems exhibit behavior that varies over time. ALS systems must respond to equipment operating cycles, repair schedules, and occasional off-nominal behavior or malfunctions. Biological components, such as bioreactors, composters, and food plant growth chambers, usually have operating cycles or other complex time behavior. Buffer sizes, material stocks, and resupply rates determine dynamic system behavior and directly affect system mass and cost. Dynamic simulation is needed to avoid the extremes of costly over-design of buffers and material reserves or system failure due to insufficient buffers and lack of stored material.

Jones, Harry

2002-01-01

45

Al Qaeda: A Different Diagnosis  

Microsoft Academic Search

When doubt and confusion reign, when things are--or look--complicated, one should revert to fundamental questions. What is Al Qaeda? This is the question addressed by this article. But as a first step, and in a broader perspective, the real danger in the world today is defined.?

XAVIER RAUFER

2003-01-01

46

Phase equilibria between NiAl and RuAl in the Ni-Al-Ru system  

SciTech Connect

Phase equilibria between NiAl and RuAl in Ni-Al-Ru alloys were studied by means of light microscopy and scanning electron microscopy. The JEOL JSM-35CF instrument was used in the electron probe microanalyses. The results indicate that the miscibility gap between NiAl and RuAl extends up to the solidus. The lattice parameter mismatch between the coexisting solid solutions based on NiAl and RuAl at temperatures of 1273 K and above is less than 0.6 percent. 10 references.

Chakravorty, S.; West, D.R.F.

1985-11-01

47

Thermal conductance of a pressed Al-Al contact  

NASA Astrophysics Data System (ADS)

Thermal conductance of a screw-fastened joint between two blocks of Al-alloys has been measured. An AlMg4.5Mn-block, the end of which is cooled by liquid helium, constitutes the upper part of the sample and the contact is formed at the face surface of a cylindrical extension of that block onto which a cylinder, made of AlMgSi1, is pressed by means of a copper-nickel screw. Pressing of the contact was carried out at room temperature by applying a defined torque, M, to the fastening screw. Three samples of the same shape but with differently treated surfaces of contact (machined flat, electro-chemically polished, with gold plated contacts) were studied. The results showed that the machined flat surfaces yield the best contact and that the contact conductance (measured in the range 4.2 K to 1.8 K) of all samples increased with increasing torque. In addition to thermal measurements, a study of the electrical conductance would be very interesting to determine the different contributions of phonon and electron heat conduction by means of the Wiedemann-Franz law. The work is useful for the GIRL (German Infra-Red Laboratory) space experiment.

Wanner, M.

1981-01-01

48

Ab? al-usayn al-Bar? and his Transmission of Biblical Materials from Kit?b al-D?n wa-al-Dawla by Ibn Rabban al-abar?: The Evidence from Fakhr al-D?n al-R?z?'s Maf?t? al-ghayb  

Microsoft Academic Search

The authenticity of the Kit?b al-d?n wa-al-dawla by the Nestorian convert to Islam, Ab? al-asan ?Al? b. Sahl Rabban al-abar? (d. ca. 251\\/865), has been discussed since the publication of the text by A. Mingana in 1922\\/23. A comparison between the chapter of the Twelver Sh??? Sad?d al-D?n Mam?d b. ?Al? al-imma? al-R?z?'s (d. after 600\\/1204) Munqidh min al-taql?d discussing

Sabine Schmidtke

2009-01-01

49

Al in computer games: Survey and perspectives  

Microsoft Academic Search

Computer games have traditionally implemented empirical solutions to many Al problems and are now turning to more traditional Al algorithms. After introducing the role of Al in gameplay, we review the main techniques used in current computer games such as Finite-State Transition Networks, rule-based systems and search algorithms. We describe the implementation of Al in several commercial computer games, as

M. Cavazza

2000-01-01

50

Tunneling through Al/AlOx/Al junction: Analytical models and first-principles simulations  

NASA Astrophysics Data System (ADS)

Ultrathin AlOx layers are nowadays widely employed to make tunneling junctions and, as a common practice, experimental transport data are often rationalized in terms of analytical models invoking effective electronic and geometric properties of the oxide layer. In this paper we examine the reliability of such models by performing first-principles simulations of the transport properties of Al/AlOx/Al junctions. The band gap, effective mass, and interface width obtained from ground state density-functional calculations are used within a potential barrier model, known also as the Simmons model, and its predictions of the conductance are compared with first-principles results. We also propose an analytical expression for the conductance based on a tight-binding model of the interface oxide. We show that the success of the potential barrier model in fitting experimental transport measurements rests on its formal similarity with the tight binding model which, in contrast to the former, is directly related to the realistic electronic structure of the interface.

Zemanová Diešková, M.; Ferretti, A.; Bokes, P.

2013-05-01

51

Inhibition of Al-induced root elongation and enhancement of Al-induced peroxidase activity in Al-sensitive and Al-resistant barley cultivars are positively correlated  

Microsoft Academic Search

The quantitative changes in peroxidase activity and composition of anionic and cationic isoperoxidases were investigated in roots of two barley cultivars differing in Al resistance. Root growth of Al-resistant cv. Bavaria was in lesser extent reduced by Al treatment (23% after 24 h Al-treatment), whereas 40% reduction of the root growth was observed in Al-sensitive cv. Alfor. The strong root

Ladislav Tamás; Jana Huttová; Igor Mistrík

2003-01-01

52

Applied Kinesiology als funktionelle Neurologie  

Microsoft Academic Search

Die muskuläre Diagnostik und Therapie, die noch vor einigen Jahren als die Domäne der Physiotherapie angesehen wurde, hält\\u000a erfreulicherweise mehr und mehr Einzug in die ärztliche Manualtherapie. Und auch hier setzt sich das Bewußtsein durch, dass\\u000a Knochen von Muskeln bewegt werden und es nicht ausreicht, Gelenke zu manipulieren, sondern dass ebenso die sie bewegenden\\u000a Muskeln behandelt werden müssen. Oder, nach

H. Garten

2000-01-01

53

Al-Hadith Text Classifier  

Microsoft Academic Search

This study explore the implementation of a text classification method to classify the prophet Mohammed (PBUH) hadiths (sayings) using Sahih Al-Bukhari classification. The sayings explain the Holy Qur`an, which considered by Muslims to be the direct word of Allah. Present method adopts TF\\/IDF (Term Frequency-Inverse Document Frequency) which is used usually for text search. TF\\/IDF was used for term weighting,

Mohammed Naji Al-Kabi; Ghassan Kanaan; Riyad Al-Shalabi; Saja I. Al-Sinjilawi; Ronza S. Al-Mustafa

2005-01-01

54

Al-Hadith Text Classifier  

Microsoft Academic Search

This study explores the implementation of a text classification method to classify the prophet Mohammed (PBUB) hadiths (sayings) using Sahih Al-Bukhari classification. The sayings explain the Holy Qur'an, which considered by Muslims to be the direct word of Allah. Present method adopts TF\\/IDF (Term Frequency-Inverse Document Frequency) which is used usually for text search. TF\\/IDF was used for term weighting,

Mohammed Naji Al-Kabi

2005-01-01

55

Nucleants of Eutectic Silicon in Al-Si Hypoeutectic Alloys: ?-(Al, Fe, Si) or AlP Phase  

NASA Astrophysics Data System (ADS)

A thermodynamic description of the Al-Si-P-Fe quaternary system focused on Al-(Si)-rich alloys is developed. The solidification sequence in typical Al-7Si cast alloys is derived using thermodynamic calculations of the phase diagrams and solidification simulation under Scheil and constrained Scheil conditions. The previously claimed nucleation of eutectic silicon by ?-(Al,Fe,Si) particles is not possible because under all conditions, ?-(Al,Fe,Si) precipitates after (Si) in pertinent alloys. Variation of P in the ppm range is crucial because it changes the solidification sequence of AlP and (Si).

Liang, Song-Mao; Schmid-Fetzer, Rainer

2014-11-01

56

Nucleants of Eutectic Silicon in Al-Si Hypoeutectic Alloys: ?-(Al, Fe, Si) or AlP Phase  

NASA Astrophysics Data System (ADS)

A thermodynamic description of the Al-Si-P-Fe quaternary system focused on Al-(Si)-rich alloys is developed. The solidification sequence in typical Al-7Si cast alloys is derived using thermodynamic calculations of the phase diagrams and solidification simulation under Scheil and constrained Scheil conditions. The previously claimed nucleation of eutectic silicon by ?-(Al,Fe,Si) particles is not possible because under all conditions, ?-(Al,Fe,Si) precipitates after (Si) in pertinent alloys. Variation of P in the ppm range is crucial because it changes the solidification sequence of AlP and (Si).

Liang, Song-Mao; Schmid-Fetzer, Rainer

2014-09-01

57

The Collections - Dar al-Athar al-Islamiyyah  

NSDL National Science Digital Library

Regarded by experts as one of a handful of the most comprehensive collections of Islamic art in the world, the al-Sabah holdings in Kuwait feature 20,000 objects from geographically and chronologically diverse locations. Nine categories - Metals, Ceramics, Glass, Ivory & Wood, Jewelry & Hardstone, Numismatics, Rugs & Textiles, Manuscripts & Calligraphy, and Stone & Stucco - can be accessed from the collections page with the click of a mouse. Within each category, short essays contextualize the beautiful photographs of ancient, medieval, and modern Islamic art in a wide variety of mediums and styles.

58

Synthesis of AlN/Al Polycrystals along with Al Nanoparticles Using Thermal Plasma Route  

NASA Astrophysics Data System (ADS)

This paper for the first time reports the (200) oriented growth of hexagonal Aluminum nitride crystals during synthesis of aluminum nanoparticles in dc transferred arc thermal plasma reactor by gas phase condensation in nitrogen plasma. The structural and morphological study of as synthesized AlN crystal and aluminium nanoparticles was done by using the x-ray diffraction method, scanning electron microscopy and transmission electron microscopy.

Kanhe, Nilesh S.; Nawale, A. B.; Kulkarni, N. V.; Bhoraskar, S. V.; Mathe, V. L.; Das, A. K.

2011-07-01

59

Investigation of Wear Anisotropy in a Severely Deformed Al-Al3Ti Composite  

NASA Astrophysics Data System (ADS)

In the current investigation, Al-Al3Ti composite was processed by equal channel angular pressing (ECAP). ECAP was carried out using routes A and BC up to eight passes of deformation. It was observed that increasing the number of ECAP passes causes fragmentation of Al3Ti platelet particles and decreases their sizes compared to their original sizes in the undeformed Al-Al3Ti specimens. Moreover, the microstructure of route A-ECAPed Al-Al3Ti composite samples showed a strong alignment of the fragmented Al3Ti particles parallel to the pressing axis. On the other hand, ECAPed Al-Al3Ti alloy specimens by route BC have a relatively homogeneous distribution of Al3Ti particles. Because of the platelet Al3Ti particle fragmentation by ECAP, all the ECAPed specimens showed small anisotropy in their wear property in spite of this observed anisotropic microstructure induced by route A-ECAP.

El-Hadad, Shimaa; Sato, Hisashi; Watanabe, Yoshimi

2012-09-01

60

Investigation of Wear Anisotropy in a Severely Deformed Al-Al3Ti Composite  

NASA Astrophysics Data System (ADS)

In the current investigation, Al-Al3Ti composite was processed by equal channel angular pressing (ECAP). ECAP was carried out using routes A and BC up to eight passes of deformation. It was observed that increasing the number of ECAP passes causes fragmentation of Al3Ti platelet particles and decreases their sizes compared to their original sizes in the undeformed Al-Al3Ti specimens. Moreover, the microstructure of route A-ECAPed Al-Al3Ti composite samples showed a strong alignment of the fragmented Al3Ti particles parallel to the pressing axis. On the other hand, ECAPed Al-Al3Ti alloy specimens by route BC have a relatively homogeneous distribution of Al3Ti particles. Because of the platelet Al3Ti particle fragmentation by ECAP, all the ECAPed specimens showed small anisotropy in their wear property in spite of this observed anisotropic microstructure induced by route A-ECAP.

El-Hadad, Shimaa; Sato, Hisashi; Watanabe, Yoshimi

2012-05-01

61

Benefits for Military Veterans with ALS  

MedlinePLUS

... Share Print Military Veterans Resources for Military Veterans, Families & Survivors The ALS Association is working everyday to support people with ALS and their families, including our heroes who have served in the ...

62

Effects of the Al content on pore structures of porous TieAl alloys  

SciTech Connect

Porous TieAl alloys with different nominal compositions were fabricated through a reactive synthesis of Ti and Al elemental powders. It has been found that the pore parameters vary with the Al contents, indicating that the nature of the pores can be manipulated through changing the Al contents. In addition, detailed structural characterizations showed that the fabricated porous TieAl alloys can have three crystalline phases (i.e., a2-Ti3Al, g-TiAl, and TiAl3) when using different compositions. The fundamental reasons behind these phenomena have been explored.

Jaing, Y [State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China; He, Y H [State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China; Xu, N P [Membrane Science and Technology Research Center, Nanjing University of Technology, Nanjing 210009, C; Zou, J [School of Engineering and Centre for Microscopy and Microanalysis, The University of Queensland, QLD; Huang, B [State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China; Lui, C T [Oak Ridge National Laboratory (ORNL)

2008-01-01

63

Delsuc et al. Hexapods resurrected Hexapods Resurrected  

E-print Network

Delsuc et al. Hexapods resurrected - 1 - Hexapods Resurrected (Technical comment on: "Hexapod.1126/science.1086558 #12;Delsuc et al. Hexapods resurrected - 2 - Abstract Nardi et al. (Science, 21 March 2003, 1887) suggested that extant hexapods might be diphyletic based on the analysis of amino acids sequences

Paris-Sud XI, Université de

64

(12) United States Patent Glazer et al.  

E-print Network

. Dynamite Blvd., Phoenix, AZ (US) 85085; Michael Barrett, 9182 E. Carribean La., Scottsdale, AZ (US) 85260 2003/0131048 Al 7/2003 Najork 5,892,904 A 411999 Atkinson et aI. 2003/0158823 Al 8/2003 Fulton et al. 5

Shamos, Michael I.

65

(12) United States Patent Bezos et al.  

E-print Network

et al. 5,724,424 A 311998 Gifford 5,745,681 A 411998 Levine et al. 5,812,769 A * 911998 Graber et al by that associate. 25 Claims, 14 Drawing Sheets 120 ",,//~~ENRO;PAllS~7~s~:W~I COOKIE PROCESSING SY I IREFERRAL

Shamos, Michael I.

66

Aluminium distribution in ZSM-5 revisited: The role of Al-Al interactions  

SciTech Connect

We present a theoretical study of the distribution of Al atoms in zeolite ZSM-5 with Si/Al=47, where we focus on the role of Al-Al interactions rather than on the energetics of Al/Si substitutions at individual sites. Using interatomic potential methods, we evaluate the energies of the full set of symmetrically independent configurations of Al siting in a Si{sub 94}Al{sub 2}O{sub 192} cell. The equilibrium Al distribution is determined by the interplay of two factors: the energetics of the Al/Si substitution at an individual site, which tends to populate particular T sites (e.g., the T14 site), and the Al-Al interaction, which at this Si/Al maximises Al-Al distances in general agreement with Dempsey's rule. However, it is found that the interaction energy changes approximately as the inverse of the square of the distance between the two Al atoms, rather than the inverse of the distance expected if this were merely charge repulsion. Moreover, we find that the anisotropic nature of the framework density plays an important role in determining the magnitude of the interactions, which are not simply dependent on Al-Al distances. - Graphical abstract: Role of Al-Al interactions in high silica ZSM-5 is shown to be anisotropic in nature and not dependent solely on Coulombic interactions. Highlights: Black-Right-Pointing-Pointer Si-Al distribution in ZSM-5 is revisited, stressing the role of the Al-Al interaction. Black-Right-Pointing-Pointer Coulomb interactions are not the key factors controlling the Al siting. Black-Right-Pointing-Pointer Anisotropy of the framework is identified as a source of departure from Dempsey's rule.

Ruiz-Salvador, A. Rabdel, E-mail: rabdel@imre.oc.uh.cu [Group of Materials Developed by Design, Division of Chemistry and Technology of Materials, Institute of Materials Science and Engineering (IMRE), University of Havana, Havana 10400 (Cuba); Grau-Crespo, Ricardo; Gray, Aileen E.; Lewis, Dewi W. [Department of Chemistry, University College London, 20 Gordon Street, London, WC1H OAJ (United Kingdom)] [Department of Chemistry, University College London, 20 Gordon Street, London, WC1H OAJ (United Kingdom)

2013-02-15

67

Opportunity's 'Rub al Khali' Panorama  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Click on the image for Opportunity's 'Rub al Khali' Panorama (QTVR)

This panoramic image, dubbed 'Rub al Khali,' was acquired by NASA's Mars Exploration Rover Opportunity on the plains of Meridiani during the period from the rover's 456th to 464th sols on Mars (May 6 to May 14, 2005). Opportunity was about 2 kilometers (1.2 miles) south of 'Endurance Crater' at a place known informally as 'Purgatory Dune.'

The rover was stuck in the dune's deep fine sand for more than a month. 'Rub al Khali' (Arabic translation: 'the empty quarter') was chosen as the name for this panorama because it is the name of a similarly barren, desolate part of the Saudi Arabian desert on Earth.

The view spans 360 degrees. It consists of images obtained in 97 individual pointings of the panoramic camera. The camera took images with five camera filters at each pointing. This 22,780-by-6,000-pixel mosaic is an approximately true-color rendering generated using the images acquired through filters admitting light wavelengths of 750, 530, and 480 nanometers.

Lighting varied during the nine sols it took to acquire this panorama, resulting in some small image seams within the mosaic. These seams have been smoothed in sky parts of the mosaic to better simulate the vista that a person would see if able to view it all at the same time on Mars.

Opportunity's tracks leading back to the north (center of the panorama) are a reminder of the rover's long trek from Endurance Crater. The deep ruts dug by Opportunity's wheels as it became stuck in the sand appear in the foreground. The crest and trough of the last ripple the rover crossed before getting stuck is visible in the center. These wind-formed sand features are only about 10 to 15 centimeters (4 to 6 inches) tall. The crest of the actual ripple where the rover got stuck can be seen just to the right of center. The tracks and a few other places on and near ripple crests can be seen in this color image to be dustier than the undisturbed or 'normal' plains soils in Meridiani. Since the time these ruts were made, some of the dust there has been blown away by the wind, reaffirming the dynamic nature of the martian environment, even in this barren, ocean-like desert of sand.

2005-01-01

68

The effects of boron in TiAl/Ti/sub 3/Al  

SciTech Connect

The authors discuss the TiAl/Ti/sub 3/Al interfacial misfit dislocations structures investigated by TEM in Ti-45Al alloy and Ti-45Al/TiB/sub 2/ composite. For TiAl with c/a = 1.02, only a single set of misfit dislocation arrays are crystallographically possible; these were observed in Ti-45Al alloy. However, the observation of three sets of misfit dislocation arrays in the Ti-45Al/TiB/sub 2/ composite suggests that the occupation of octahedral sites in the TiAl structure by excess boron was responsible for a decrease in the c/a ratio leading to an increased fcc character of the TiAl at the TiAl/Ti/sub 3/Al interface.

Feng, C.R.; Michel, D.J.; Crowe, C.R. (Naval Research Lab., Washington, DC (USA). Material Science and Technology Div.)

1989-10-01

69

Instandhaltungsmanagement als Gestaltungsfeld Ganzheitlicher Produktionssysteme  

NASA Astrophysics Data System (ADS)

Sich kontinuierlich verändernde Rahmenbedingungen, wie beispielsweise eine steigende Variantenvielfalt, verkürzte Produktlebenszyklen sowie Kundenforderungen nach höherer Qualität, kürzeren Lieferzeiten und geringeren Kosten, fordern von produzierenden Unternehmen eine stetige Anpassung der Prozesse, der Organisation und der Strukturen. Seit den 90er Jahren versuchen immer mehr deutsche Unternehmen diesen veränderten Anforderungen mit der Einführung eines Ganzheitlichen Produktionssystems (GPS) zu begegnen. Ganzheitliche Produktionssysteme sind dabei in ihren Grundlagen an das Toyota Produktionssystem angelehnt, vereinigen aber auch weitere Methoden zu einem unternehmensspezifischen Regelwerk. Im Rahmen des langfristigen Trends zu unternehmensindividuellen Produktionssystemen wird sowohl in der Industrie als auch in der Forschung intensiv über das Toyota Produktionssystem, Lean Production, Lean Management und Ganzheitliche Produktionssysteme diskutiert, werden Konzepte zu Implementierung und Betrieb erstellt und die Wirtschaftlichkeit untersucht.

Dombrowski, Uwe; Schulze, Sven; Otano, Isabel Crespo

70

Oxidation induced softening in Al nanowires  

NASA Astrophysics Data System (ADS)

The mechanical properties of metallic nanowires depend dramatically on the atmospheric conditions. Molecular-dynamics simulations with ReaxFF were conducted to study tensile elastic deformation of oxidized Al nanowires. The thin amorphous oxide shell formed around Al nanowires had a very low Young's modulus of 26 GPa, due to its low density and low Al-O coordination. Consequently, for diameters less than 100 nm, the composite Young's modulus of oxide-covered Al nanowires showed a size dependence implying that in this case "smaller is softer." The model developed also explained the discrepancies in the reported modulus values of nanometer-scale Al thin films.

Sen, Fatih G.; Qi, Yue; van Duin, Adri C. T.; Alpas, Ahmet T.

2013-02-01

71

Accumulation of Al in Root Mucilage of an Al-Resistant and an Al-Sensitive Cultivar of Wheat.  

PubMed Central

To estimate rates of Al accumulation within the symplasm, all apoplastic pools of Al need to be eliminated or accounted for. We have developed a revised kinetic protocol that allows us to estimate the contribution of mucilage-bound Al to total, nonexchangeable Al, and to eliminate the mucilage as an apoplastic pool of Al. By comparing the Al content of excised root tips (2 cm) of wheat (Triticum aestivum L.) with and without the removal of the mucilage (using a 10-min wash in 1 M NH4Cl), we found that Al bound to the mucilage accounted for approximately 25 to 35% of Al remaining after desorption in citric acid. The kinetics of Al uptake into mucilage were biphasic, with a rapid phase occurring in the first 30 min of uptake, followed by a linear phase occurring in the remainder of the experimental period (180 min). By adopting a step for removal of mucilage into our existing kinetic protocol, we have been able to isolate a linear phase of uptake with only a slight deviation from linearity in the first 5 min. Although we cannot unambiguously identify this phase of uptake as uptake into the symplasm, we believe this new protocol provides us with the most accurate quantitative estimate of symplastic Al yet available. PMID:12226458

Archambault, D. J.; Zhang, G.; Taylor, G. J.

1996-01-01

72

Diffusion in the Ti-Al system  

SciTech Connect

Many properties of industrial Ti-Al alloys, such as high-temperature stability of the lamellar structure and creep resistance, are determined by diffusion rates in the phases and along the interfaces. The knowledge of diffusion characteristics and fundamental understanding of diffusion mechanisms are of great importance to the research and design of industrial Ti-Al alloys. This paper gives an overview of recent progress in experimental and theoretical studies of diffusion behavior in the phases of the Ti-Al system. The experimental methods used in modern diffusion measurements are briefly described, and recent experimental results for Ti and Al diffusion in {alpha}-Ti(Al), {beta}-Ti(Al), and intermetallic phases {alpha}{sub 2}-Ti{sub 3}Al and {gamma}-TiAl, are summarized. The results for interdiffusion and impurity diffusion in these phases are also discussed in detail. The second part of the paper provides an overview of current understanding of point defects and diffusion mechanisms in Ti{sub 3}Al and TiAl. A statistical model of point-defect disorder in ordered compounds is presented and applied to Ti{sub 3}Al and TiAl using input data generated with embedded-atom potentials. Possible atomic mechanisms of diffusion in these compounds are analyzed in detail, and methods of diffusion calculations under different mechanisms are reviewed. The relative importance of different mechanisms in Ti{sub 3}Al and TiAl is evaluated by comparing their estimated activation energies. Prospective topics of further experimental and theoretical research in this area are outlined.

Mishin, Y.; Herzig, C.

2000-02-09

73

Reactive Plasma Spraying of Fine Al2O3/AlN Feedstock Powder  

NASA Astrophysics Data System (ADS)

Reactive plasma spraying (RPS) is a promising technology for in situ formation of aluminum nitride (AlN) coatings. Recently, AlN-based coatings were fabricated by RPS of alumina (Al2O3) powder in N2/H2 thermal plasma. This study investigated the feasibility of RPS of a fine Al2O3/AlN mixture and the influence of the plasma gases (N2, H2) on the nitriding conversion, and coating microstructure and properties. Thick AlN/Al2O3 coatings with high nitride content were successfully fabricated. The coatings consist of h-AlN, c-AlN, Al5O6N, ?-Al2O3, and a small amount of ?-Al2O3. Use of fine particles enhanced the nitriding conversion and the melting tendency by increasing the surface area. Furthermore, the AlN additive improved the AlN content in the coatings. Increasing the N2 gas flow rate improved the nitride content and complete crystal growth to the h-AlN phase, and enhanced the coating thickness. On the other hand, though the H2 gas is required for plasma nitriding of the Al2O3 particles, increasing its flow rate decreased the nitride content and the coating thickness. Remarkable influence of the plasma gases on the coating composition, microstructure, and properties was observed during RPS of the fine particles.

Shahien, Mohammed; Yamada, Motohiro; Yasui, Toshiaki; Fukumoto, Masahiro

2013-12-01

74

Atom probe analysis of AlN interlayers in AlGaN/AlN/GaN heterostructures  

SciTech Connect

Atom probe tomography was used to characterize AlN interlayers in AlGaN/AlN/GaN heterostructures grown by plasma-assisted molecular beam epitaxy (PAMBE), NH{sub 3}-based molecular beam epitaxy (NH{sub 3}-MBE), and metal-organic chemical vapor deposition (MOCVD). The PAMBE-grown AlN interlayer had the highest purity, with nearly 100% of group-III sites occupied by Al. The group-III site concentrations of Al for interlayers grown by NH{sub 3}-MBE and MOCVD were {approx}85% and {approx}47%, respectively. Hall measurements were performed to determine the two-dimensional electron gas mobility and sheet concentration. Sheet concentrations were {approx}25%-45% higher with molecular beam epitaxy than with MOCVD, and these results matched well with atom probe data.

Mazumder, Baishakhi; Kaun, Stephen W.; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)] [Materials Department, University of California, Santa Barbara, California 93106 (United States); Lu, Jing; Keller, Stacia; Mishra, Umesh K. [Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States)] [Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States)

2013-03-18

75

Adhesion and nonwetting-wetting transition in the Al\\/alpha-Al2O3 interface  

Microsoft Academic Search

Using a reactive force field (ReaxFF), we investigated the structural, energetic, and adhesion properties, of both solid and liquid Al\\/alpha-Al2O3 interfaces. The ReaxFF was developed solely with ab initio calculations on various phases of Al and Al2O3 and Al-O-H clusters. Our computed lattice constants, elastic constants, surface energies, and calculated work of separation for the solid-solid interface agree well with

Qing Zhang; Tahir Çagin; Adri van Duin; William A. Goddard; Yue Qi; Louis G. Hector

2004-01-01

76

Oxidation resistance of intermetallic compounds Al 3 Ti and TiAl  

Microsoft Academic Search

The oxidation kinetics and morphological features of Al3Ti and TiAl were investigated. The oxidation resistance of Al3Ti is much better than that of TiAl, for example, by a factor of about 30 at 1000° C for 48 h. The big difference in the oxidation resistance is related to the characteristics of the external oxide scales of a protective Al2O3 or

Y. Umakoshi; M. Yamaguchi; T. Sakagami; T. Yamane

1989-01-01

77

Abrasive wear behavior of NiAl and NiAl–TiB 2 composites  

Microsoft Academic Search

Abrasive wear of NiAl and NiAl with 10, 20, and 40 vol.% TiB2 has been investigated using particles of different types and sizes. The addition of TiB2 as a particulate reinforcement to NiAl increases the hardness of the composite with respect to NiAl, and reduces the wear rate at all volume fractions on garnet and Al2O3 abrasives. Abrasion on SiC

Jeffrey A. Hawk; David E. Alman

1999-01-01

78

Toxicity of Al to Desulfovibrio desulfuricans  

SciTech Connect

The toxicity of Al to Desulfovibrio desulfuricans G20 was assessed over a period of eight weeks in a modified lactate-C medium buffered at four initial pHs (5.0, 6.5, 7.2, and 8.3) and treated with five levels of added Al (none, 0.01, 0.1, 1.0, and 10 mM). At pH 5, cell populations decreased significantly and any effect of Al was negligible compared to that of pH. At higher pH, no direct impact of Al was seen at concentrations of soluble Al below 5x10-5 M. Soluble Al concentrations exceeded this level in the pH-6.5 and pH-7.2 treatments having total-Al concentrations= 1 mM and caused substantial and proportional decreases in cell populations. In contrast to the small size and vibrio morphology seen in most treatments, substantial numbers of large spirilloidal bacteria were seen in the pH-8.3 treatments, and their incidence was correlated with greater total-Al concentrations. This effect was believed to be a result of Mg deprivation stemming from adsorption/coprecipitation of Mg with Al hydroxy-sulfate gels rather than a direct response to high total-Al levels. Calculations of soluble-Al speciation suggested the presence of the Al13O4(OH)24(H2O)127+''tridecamer'' cation in the pH-6.5 and pH-7.2 treatments showing direct Al toxicity. Analysis of inoculated and control samples from the pH-6.5 and pH-8.3 10-mM Al treatments by 27Al nuclear-magnetic-resonance spectroscopy yielded broad 4800-Hz resonances at 58 ppm, near the 63-ppm resonance expected for the tridecamer cation. These resonances were independent of sample filtration through 25,000 MWCO membranes and attributed to self-assembled colloidal clusters of hydrophobic tridecamer species that had been neutralized by sorption of lactate and sulfate anions. Although indirect effects of Al addition were believed to have caused the lower cell populations observed in the pH-8.3 treatments, the NMR data suggest that direct effects of Al toxicity stemming from tridecamer colloids cannot be excluded.

Amonette, James E.; Russell, Colleen K.; Carosino, Katie A.; Robinson, Nicole L.; Ho, Jennifer T.

2003-07-02

79

New Al–Mg–Sc alloys  

Microsoft Academic Search

Data on new 01515, 01523, 01535, 01545, 01570 and 01571 wrought weldable alloys based on the Al–Mg–Sc system are presented. These alloys differ from each other, mainly, by magnesium content and belong to the family of non-heat-treatable alloys. Wrought Al–Mg–Sc alloy semiproducts as-hot worked or as-annealed show much higher properties (especially yield strength) than those made from conventional Al–Mg alloys

Yu. A Filatov; V. I Yelagin; V. V Zakharov

2000-01-01

80

Al Pie De La Letra  

PubMed Central

Background and Purpose Ethnic minorities are at higher stroke risk than non-Hispanic whites yet are less likely to have optimal vascular risk factor control. There is a need to develop culturally sensitive strategies for enhancing vascular risk reduction in minority patients with stroke. This study aimed to develop a postdischarge report card to boost treatment adherence among elderly Spanish-speaking patients with stroke within an urban health system. Methods This study included a total of 13 Spanish-only speaking participants aged ?60 years discharged from a local government hospital in Los Angeles within 18 months of an index ischemic stroke and 6 caregivers engaged in focus groups and interviews. Structured interviews were conducted with 11 care providers and 9 administrators at the hospital. Framework analysis examined the data and elicited themes to adapt a pre-existing patient report card tool. Results Spontaneously using the same phrase, “Al pie de la letra,” several participants expressed a need to follow medical instructions accurately to prevent recurrent stroke and identified barriers/facilitators for doing so. They made comments about the pre-existing report card, advising several changes, including the clarification of phrases, and written instructions to explain the need for the card and how to fill it out. The providers and administrators recommended avenues for successfully using the card at the hospital. A new report card was created that incorporated all major perspectives. Conclusions Crafting a culturally sensitive tool for promoting treatment adherence in elderly Spanish-only-speaking patients with stroke within an urban health system using a participatory methodology is feasible. The efficacy of this new report card should be tested in a randomized controlled trial. PMID:20167904

Ovbiagele, Bruce

2014-01-01

81

Internal Detoxification Mechanism of Al in Hydrangea (Identification of Al Form in the Leaves).  

PubMed Central

An internal detoxification mechanism for Al was investigated in an Al-accumulating plant, hydrangea (Hydrangea macrophylla), focusing on Al forms present in the cells. The leaves of hydrangea contained as much as 15.7 mmol Al kg-1 fresh weight, and more than two-thirds of the Al was found in the cell sap. Using 27Al- nuclear magnetic resonance, the dominant peak of Al was observed at a chemical shift of 11 to 12 parts per million in both intact leaves and the extracted cell sap, which is in good accordance with the chemical shift for the 1:1 Al-citrate complex. Purification of cell sap by molecular sieve chromatography (Sephadex G-10) combined with ion-exclusion chromatography indicated that Al in fractions with the same retention time as citric acid contributed to the observed 27Al peak in the intact leaves. The molar ratio of Al to citric acid in the crude and purified cell sap approximated 1. The structure of the ligand chelated with Al was identified to be citric acid. Bioassay experiments showed that the purified Al complex from the cell sap did not inhibit root elongation of corn (Zea mays L.) and the viability of cells on the root tip surface was also not affected. These observations indicate that Al is bound to citric acid in the cells of hydrangea leaves. PMID:12223659

Ma, J. F.; Hiradate, S.; Nomoto, K.; Iwashita, T.; Matsumoto, H.

1997-01-01

82

Exercise does not Increase ALS Risk  

MedlinePLUS

... for potentially confounding variables, such as the degree athletes who developed ALS used legal or illegal medications, took dietary supplements, and were exposed to pesticides or other toxins ...

83

Interfacial Phenomena in Al/Al, Al/Cu, and Cu/Cu Joints Soldered Using an Al-Zn Alloy with Ag or Cu Additions  

NASA Astrophysics Data System (ADS)

The studies of soldered joints were carried out in systems: Al/solder/Al, Al/solder/Cu, Cu/solder/Cu, where the solder was (Al-Zn)EUT, (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Ag and (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Cu addition. Brazing was performed at 500 °C for 3 min. The EDS analysis indicated that the composition of the layers starting from the Cu pad was CuZn, Cu5Zn8, and CuZn4, respectively. Wetting tests were performed at 500 °C for 3, 8, 15, and 30 min, respectively. Thickness of the layers and their kinetics of growth were measured based on the SEM micrographs. The formation of interlayers was not observed from the side of Al pads. On the contrary, dissolution of the Al substrate and migration of Al-rich particles into the bulk of the solder were observed.

Pstru?, Janusz; Gancarz, Tomasz

2014-05-01

84

[Management and care for patients with ALS].  

PubMed

For the past decade or so, the research in ALS has dramatically changed, coinciding with the discovery of SOD1 mutations, the generation of SOD1 transgenic rodents, and the introduction of riluzole. The ALS practice guidelines have been published in a number of countries, whereas the National Database has shown the actual reality of patient practice in ALS. Multidisciplinary ALS Clinics, consisting of a team of health care professionals, provide highly specialized quality care for patients and families, and have become the standard of care in many countries. A number of mostly retrospective studies report that non-invasive positive pressure ventilation prolongs survival and improves the quality of life and other functions. Enteral feeding certainly improves quality of life, but it is still uncertain if it prolongs survival. Although end of life issues in ALS care have been difficult more and more ALS clinicians are paying serious attention to it. Clinical trials are imperative to find effective medications for ALS, and many different pharmacological agents, based on a number of different hypotheses in ALS, are being actively tested or are about to be tested in the near future. Undoubtedly, we are in the midst of incredible progress in ALS. PMID:17432192

Mitsumoto, Hiroshi; Howe, Wesley J

2006-11-01

85

?-Phase Formation in Ni-Al Systems  

NASA Astrophysics Data System (ADS)

First-principles full-potential linear muffin-tin orbital method (FPLMTO) were performed for ?-type structural phase transformation for B2 (b.c.c.) NiAl and Ni_2Al alloys. In contrast to the NiAl system but in agreement with experiments, the results of our calculation showed that the Ni_2Al system is unstable with respect to this kind of transformation. To better understand the origin of stability and instability in each system, we also used a pair potential for modeling the interactions between the atoms. Calculated lattice parameters for the structures are in excellent agreement with the experimental data.

Albers, R. C.; Sanati, M.; Pinski, F. J.

1998-03-01

86

Anodic Behavior of Al and the Alloys Al-In and Al-In-Ga in Aluminum-Air Batteries.  

National Technical Information Service (NTIS)

By recording of the polarization characteristics and measurement of the currents of self-dissolution, the anodic behavior of aluminum and the alloys Al-In and Al-In-Ga was tested under the operating conditions of aluminum-air batteries. The tests were con...

D. M. Drazic, A. R. Despic, S. K. Zecevic

1979-01-01

87

Effects of the Al content on pore structures of porous TieAl alloys  

SciTech Connect

PorousTi Alalloys with different nominal compositions were fabricated through a reactive synthesis of Ti and Al elemental powders. It has been found that the pore parameters vary with the Al contents, indicating that the nature of the pores can be manipulated through changing the Al contents. In addition, detailed structural characterizations showed that the fabricated porousTi Alalloys can have three crystalline phases (i.e., 2-Ti3Al, -TiAl, and TiAl3) when using different compositions. The fundamental reasons behind these phenomena have been explored.

Jiang, Y [State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China; He, Y H [State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China; Zou, J [School of Engineering and Centre for Microscopy and Microanalysis, The University of Queensland, QLD; Huang, B [State Key Laboratory for Powder Metallurgy, Central South University, Changsha 410083, China; Liu, C [Oak Ridge National Laboratory (ORNL)

2008-01-01

88

Investigation of TiAl\\/Ti 2AlC composites prepared by spark plasma sintering  

Microsoft Academic Search

TiAl\\/Ti2AlC composites were produced by spark plasma sintering technology from mixed powders of Ti, Al and TiC. X-ray diffraction (XRD) patterns showed that the sintered products mainly consisted of TiAl and Ti2AlC phases. Electric probe microcosmic analysis (EPMA) photos indicated different microstructures depending on composition. In one case, when 7vol.%TiC was mixed in the starting powders, the produced Ti2AlC particles

Bingchu Mei; Yoshinari Miyamoto

2002-01-01

89

United States Patent [19] Miura et al.  

E-print Network

such as boron neutron capture therapy and photodynamic therapy. 3 Therapy for Cancer, Kobe, Japan (Oct. 31--Nov. 4, 1994). Miura et al., "Synthesis and Spectroscopic Capture Therapy", Tetrahedron Letters, 31(16), pp. 2247--2250 (1990). Chiusoli et al., "Synthesis

Shelnutt, John A.

90

Al Shabaab's Foreign Threat to Somalia  

Microsoft Academic Search

This article focuses on the threat to Somalia by al Shabaab (The Youth), an extremist organization that controls most of southern and central Somalia. It learned its strategy and tactics from al Qaeda and the Taliban and relies heavily on a relatively small number of foreign fighters, most of whom are Somalis with foreign passports from the large Somali diaspora.

David Shinn

2011-01-01

91

Everyday Life with ALS: A Practical Guide  

MedlinePLUS

... MDA. Flu shots can help protect the respiratory system. Online support MDA’s ALS Division offers news and a series of regularly scheduled online chats, plus occasional conferences with ALS specialists and experts. Transcripts of past chats are posted. MDA also ...

92

United States Patent [19] Church et al.  

E-print Network

United States Patent [19] Church et al. [54] CHARACTERIZATION OF INDIVIDUAL POLYMER MOLECULES BASED al.. "Effect of Point Mutations on the in-Vitro Pore Properties ofMaltoporin. a Protein physical changes across an interface between two pools of media as the linear polymer traverses

Church, George M.

93

Quantitatively probing the Al distribution in zeolites.  

PubMed

The degree of substitution of Si(4+) by Al(3+) in the oxygen-terminated tetrahedra (Al T-sites) of zeolites determines the concentration of ion-exchange and Brønsted acid sites. Because the location of the tetrahedra and the associated subtle variations in bond angles influence the acid strength, quantitative information about Al T-sites in the framework is critical to rationalize catalytic properties and to design new catalysts. A quantitative analysis is reported that uses a combination of extended X-ray absorption fine structure (EXAFS) analysis and (27)Al MAS NMR spectroscopy supported by DFT-based molecular dynamics simulations. To discriminate individual Al atoms, sets of ab initio EXAFS spectra for various T-sites are generated from DFT-based molecular dynamics simulations, allowing quantitative treatment of the EXAFS single- and multiple-photoelectron scattering processes out to 3-4 atom shells surrounding the Al absorption center. It is observed that identical zeolite types show dramatically different Al distributions. A preference of Al for T-sites that are part of one or more 4-member rings in the framework over those T-sites that are part of only 5- and 6-member rings in an HBEA150 zeolite has been determined using this analysis. PMID:24815517

Vjunov, Aleksei; Fulton, John L; Huthwelker, Thomas; Pin, Sonia; Mei, Donghai; Schenter, Gregory K; Govind, Niranjan; Camaioni, Donald M; Hu, Jian Zhi; Lercher, Johannes A

2014-06-11

94

[Electrodiagnosis of ALS: its practical aspects].  

PubMed

Electrodiagnostic methods, especially needle EMG plays an important role for the ALS diagnosis. Existing diagnostic criteria such as revised El Escorial criteria (R-EEC) and Awaji algorithm have a drawback of low sensitivity. Our study revealed that the percentage of patients classified as confirmed ALS, i.e. clinically probable (laboratory supported) or higher, was 43% using the R-EEC and 37% using the Awaji algorithm. Needle EMG can strongly suggest ALS beyond these criteria. Fasciculation potentials (FPs) are sufficiently specific for ALS, and we have argued its diagnostic utitlity in ALS diagnosis. FPs are rare in other neurogenic diseases, such as cervical or lumbar spine disorders and spinal and bulbar muscular atrophy. Profuse FPs observed in both upper and lower limbs would strongly suggest ALS. EMG of the upper trapezius muscle is useful since it is easily relaxed, and the spontaneous activities in this muscle are sufficiently sensitive and specific for ALS. Inclusion body myositis (IBM) might be confused with ALS, but its differentiation is actually easy since a normal recruitment in a chronically weak muscle definitely indicates myopathy. Furthermore, EMG of the flexor digitorum profundus muscle in IBM patients would reveal typical myopathic, i.e. low-amplitude and thin, motor unit potentials. PMID:22277500

Sonoo, Masahiro; Higashihara, Mana; Hokkoku, Keiichi

2011-11-01

95

Stress Corrosion Cracking of Al-Mg and Mg-Al Alloys  

SciTech Connect

Aluminum and magnesium based alloys are being used for reducing the weight of automobiles. For structural applications they must have adequate stress corrosion resistance and yet, under some circumstances, stress corrosion cracking can occur in both alloy systems. Precipitation of the Mg rich Beta-phase (Al3Mg2) at grain boundaries of Al-Mg alloys and the Beta-phase (Mg17Al12) at grain boundaries of the Mg-Al alloys are critical factors in their stress corrosion performance. In Mg-Al, the Beta-phase is cathodic to the matrix while in the Al-Mg case, the Beta-phase is anodic to the matrix. These phases produce localized galvanic induced-corrosion that leads to intergranular stress corrosion cracking and cracking growth rates of 5 and 103 times faster than the solution treated condition, for Al-Mg and Mg-Al, respectively.

Jones, Russell H.; Vetrano, John S.; Windisch, Charles F.

2004-12-01

96

NiAl alloys for structural uses  

NASA Technical Reports Server (NTRS)

Alloys based on the intermetallic compound NiAl are of technological interest as high temperature structural alloys. These alloys possess a relatively low density, high melting temperature, good thermal conductivity, and (usually) good oxidation resistance. However, NiAl and NiAl-base alloys suffer from poor fracture resistance at low temperatures as well as inadequate creep strength at elevated temperatures. This research program explored macroalloying additions to NiAl-base alloys in order to identify possible alloying and processing routes which promote both low temperature fracture toughness and high temperature strength. Initial results from the study examined the additions of Fe, Co, and Hf on the microstructure, deformation, and fracture resistance of NiAl-based alloys. Of significance were the observations that the presence of the gamma-prime phase, based on Ni3Al, could enhance the fracture resistance if the gamma-prime were present as a continuous grain boundary film or 'necklace'; and the Ni-35Al-20Fe alloy was ductile in ribbon form despite a microstructure consisting solely of the B2 beta phase based on NiAl. The ductility inherent in the Ni-35Al-20Fe alloy was explored further in subsequent studies. Those results confirm the presence of ductility in the Ni-35Al-20Fe alloy after rapid cooling from 750 - 1000 C. However exposure at 550 C caused embrittlement; this was associated with an age-hardening reaction caused by the formation of Fe-rich precipitates. In contrast, to the Ni-35Al-20Fe alloy, exploratory research indicated that compositions in the range of Ni-35Al-12Fe retain the ordered B2 structure of NiAl, are ductile, and do not age-harden or embrittle after thermal exposure. Thus, our recent efforts have focused on the behavior of the Ni-35Al-12Fe alloy. A second parallel effort initiated in this program was to use an alternate processing technique, mechanical alloying, to improve the properties of NiAl-alloys. Mechanical alloying in the conventional sense requires ductile powder particles which, through a cold welding and fracture process, can be dispersion strengthened by submicron-sized oxide particles. Using both the Ni-35Al-Fe alloys to contain approx. 1 v/o Y2O3. Preliminary results indicate that mechanically alloyed and extruded NiAl-Fe + Y2O3 alloys when heat treated to a grain-coarsened condition, exhibit improved creep resistance at 1000 C when compared to NiAl; oxidation resistance comparable to NiAl; and fracture toughness values a factor of three better than NiAl. As a result of the research initiated on this NASA program, a subsequent project with support from Inco Alloys International is underway.

Koss, D. A.

1991-01-01

97

Al-Akhawayni's description of pulmonary circulation.  

PubMed

Since antiquity, heart function and the mechanism of blood circulation within the human body have been the focus of attention of scientists from different parts of the world. Over the passage of time, the theories and works of these scientists have resulted in the achievement of today's knowledge of circulation. The medieval Persian scholar, Al-Akhawayni Bukhari (?-983AD), is among the physicians who investigated both the anatomy and the physiology of the human body. Al-Akhawayni describes the mechanism of pulmonary circulation in his only extant book, "Hidayat al-Muta`llemin fi al-Tibb" (A Scholar's Guide to Medicine) with which he made a contribution to the development of knowledge regarding this mechanism in the medicine of the Islamic world. In this paper, Al-Akhawayni's viewpoints on anatomy and the function of the heart, its related vessels, and also pulmonary circulation will be briefly discussed. PMID:23890868

Yarmohammadi, Hassan; Dalfardi, Behnam; Rezaian, Jafar; Ghanizadeh, Ahmad

2013-10-01

98

AL(0) in municipal waste incinerator ash  

NASA Astrophysics Data System (ADS)

Disposal of municipal waste is a challenge to society. Waste volume is substantially decreased by incineration but residual ash usually contains a number of toxic components which must be immobilised to insure environmental protection. One element, chromium, is mobile and toxic in its oxidised state as Cr(VI) but it can be reduced to Cr(III) and immobilised. Reduction can be promoted by ash treatment with Fe(0) or Fe(II), but recent evidence shows that at least some Cr(VI) is reduced spontaneously in the ash. Aspects of ash behaviour suggest metallic aluminium as the reducing agent, but no direct evidence of Al(0) has been found until now. We examined filter ash from an energy-producing, municipal-waste incinerator (Vest-forbrænding) near Copenhagen. X-ray diffraction (XRD) identified expected salts of Na, K and Ca such as halite, sylvite, calcite, anhydrite and gypsum as well as quartz, feldspar and some hematite. Wave-dispersive electron microprobe produced elemen-tal maps of the ash; Al-rich areas were analysed quantitatively by comparison with standards. We identified metallic Al particles, averaging 50 to 100 micrometers in di-ameter, often with a fractured, glassy border of aluminum oxide. The particles were porous, explaining fast Cr(VI) reduction and they contained thin exsolution lamellae of Al-alloys of Pb and Cu or Mn, Fe and Ag, which provide clues of the Al(0) origin in the waste. Sometimes Al(0) occurred inside glassy globes of Al2O3. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) proved that surface Al concentrations on ash particles were below detection, confirming reactivity of the Al(0) bulk. The persistence of reduced Al through the highly oxidising combustion procedure comes as a surprise and is a benefit in the immobilisation of Cr(VI) from municipal-waste incineration residues.

Stipp, S. L.; Ronsbo, J. G.; Zunic, T. B.; Christensen, T. H.

2003-04-01

99

High temperature creep behaviour of Al-rich Ti-Al alloys  

NASA Astrophysics Data System (ADS)

Compared to Ti-rich ?-TiAl-based alloys Al-rich Ti-Al alloys offer an additional reduction of in density and a better oxidation resistance which are both due to the increased Al content. Polycrystalline material was manufactured by centrifugal casting. Microstructural characterization was carried out employing light-optical, scanning and transmission electron microscopy and XRD analyses. The high temperature creep of two binary alloys, namely Al60Ti40 and Al62Ti38 was comparatively assessed with compression tests at constant true stress in a temperature range between 1173 and 1323 K in air. The alloys were tested in the cast condition (containing various amounts of the metastable phases Al5Ti3 and h-Al2Ti) and after annealing at 1223 K for 200 h which produced (thermodynamically stable) lamellar ?-TiAl + r-Al2Ti microstructures. In general, already the as-cast alloys exhibit a reasonable creep resistance at 1173 K. Compared with Al60Ti40, both, the as-cast and the annealed Al62Ti38 alloy exhibit better creep resistance up to 1323 K which can be rationalized by the reduced lamella spacing. The assessment of creep tests conducted at identical stress levels and varying temperatures yielded apparent activation energies for creep of Q = 430 kJ/mol for the annealed Al60Ti40 alloy and of Q = 383 kJ/mol for the annealed Al62Ti38 material. The latter coincides well with that of Al diffusion in ?-TiAl, whereas the former can be rationalized by the instability of the microstructure containing metastable phases.

Sturm, D.; Heilmaier, M.; Saage, H.; Aguilar, J.; Schmitz, G. J.; Drevermann, A.; Palm, M.; Stein, F.; Engberding, N.; Kelm, K.; Irsen, S.

2010-07-01

100

Infrared brazing of TiAl using Al-based braze alloys  

Microsoft Academic Search

A novel approach for joining TiAl by infrared vacuum brazing using pure aluminum and BAlSi-4 filler metal has been reported in the study. For pure Al filler metal, the extensive presence of stable TiAl3 phase in the joint results in inherent brittleness of the bond, and it is difficult to completely remove the stable TiAl3 by heat treatment after infrared

R. K. Shiue; S. K. Wu; S. Y. Chen

2003-01-01

101

Tree fine root Ca\\/Al molar ratio – Indicator of Al and acidity stress  

Microsoft Academic Search

High soil acidity and elevated soil Al concentrations limit plant growth in many terrestrial ecosystems. Aluminium toxicity can be ameliorated by Ca. Thus, Ca\\/Al molar ratios in soil solution and in plant tissues have been proposed as superior indicators than Al concentration itself for evaluating the Al toxicity stress to trees (Cronan & Grigal, J Environ Qual 1995;24:209 – 226). This article

E. I. Vanguelova; Y. Hirano; T. D. Eldhuset; L. Sas-Paszt; M. R. Bakker; Ü. Püttsepp; I. Brunner; K. Lõhmus; D. Godbold

2007-01-01

102

Linewidth and underlayer influence on texture in submicrometer-wide Al and AlCu lines  

Microsoft Academic Search

The local texture in three types of patterned, thin-film, Al and AlCu interconnections on Si semiconductor devices is investigated by electron backscatter diffraction. Two types of standard planar metal structures were investigated: (1) blanket Al and (2) blanket Al-0.5 wt % Cu on TiN\\/Ti underlayers. Both were deposited on amorphous SiO2 substrates followed by reactive ion etching to define 0.45-10

J. L. Hurd; K. P. Rodbell; L. M. Gignac; L. A. Clevenger; R. C. Iggulden; R. F. Schnabel; S. J. Weber; N. H. Schmidt

1998-01-01

103

Linewidth and underlayer influence on texture in submicrometer-wide Al and AlCu lines  

Microsoft Academic Search

The local texture in three types of patterned, thin-film, Al and AlCu interconnections on Si semiconductor devices is investigated by electron backscatter diffraction. Two types of standard planar metal structures were investigated: (1) blanket Al and (2) blanket Al–0.5 wt % Cu on TiN\\/Ti underlayers. Both were deposited on amorphous SiO2 substrates followed by reactive ion etching to define 0.45–10

J. L. Hurd; K. P. Rodbell; L. M. Gignac; L. A. Clevenger; R. C. Iggulden; R. F. Schnabel; S. J. Weber; N. H. Schmidt

1998-01-01

104

The site occupancies of alloying elements in TiAl and Ti 3Al alloys  

Microsoft Academic Search

The site occupancies of V, Cr, Mn, Fe, Ni, Zr, Nb, Mo, Ta, Ga and Sn (1–5at.%) in TiAl alloys with different compositions, and in Ti3Al with the compositions of Ti–26at.%Al–(1–2at.%)X, were measured by the atom location channelling enhanced microanalysis (ALCHEMI) method. For TiAl alloys, the results show that Zr, Nb and Ta atoms invariably occupy Ti sites, while Fe,

Y. L. Hao; D. S. Xu; Y. Y. Cui; R. Yang; D. Li

1999-01-01

105

Corrosion Studies of 2195 Al-Li Alloy and 2219 Al Alloy with Differing Surface Treatments  

NASA Technical Reports Server (NTRS)

Corrosion studies of 2195 Al-Li and 2219 Al alloys have been conducted using the scanning reference electrode technique (SRET) and the polarization resistance (PR) technique. The SRET was used to study corrosion mechanisms, while corrosion rate measurements were studied with the PR technique. Plates of Al203 blasted, soda blasted and conversion coated 2219 Al were coated with Deft primer and the corrosion rates studied with the EIS technique. Results from all of these studies are presented.

Danford, M. D.; Mendrek, M. J.

1998-01-01

106

27Al-NQR\\/NMR Study of Kondo Semiconductor CeFe2Al10  

Microsoft Academic Search

27Al-NQR\\/NMR measurements have been performed on CeFe2Al10 in relevance to the novel phase below T0=27 K of isostructural CeRu2Al10. NQR peaks are assigned to five crystallographically inequivalent Al sites. No splitting of the NQR spectra down to 1.5 K confirms the lack of phase transition in this compound. The gaplike decrease in the spin-lattice relaxation rate 1\\/T1 above about 20

Yukihiro Kawamura; Shingo Edamoto; Tomoaki Takesaka; Takashi Nishioka; Harukazu Kato; Masahiro Matsumura; Yo Tokunaga; Shinsaku Kambe; Hiroshi Yasuoka

2010-01-01

107

A Revision of the Al-rich Region of the Sm-Al Phase Diagram: The Sm 3 Al 11 Phase  

Microsoft Academic Search

Phase equilibria in the Al-rich region of the Sm-Al binary system has been revised and updated: it has been confirmed that\\u000a Sm3Al11 is a congruently melting phase which, on cooling, undergoes catatectic decomposition Sm3Al11 ? liquid + SmAl3.

S. Delsante; R. Raggio; G. Borzone; R. Ferro

2007-01-01

108

Phase Constituents of Al-rich U-Mo-Al Alloys Examined by Transmission Electron Microscopy  

SciTech Connect

To supplement the understanding of diffusional interactions involving Al-rich region of the U-Mo-Al system, alloys with composition 85.7Al-11.44U-2.86Mo and 87.5Al-10U-2.5Mo in at.%, were examined to determine the equilibrium phase constituents at 500?C. These alloys were triple arc-melted, homogenized at 500?C for 200 hours, and water-quenched to preserve the high temperature microstructure. X-ray diffraction, scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (XEDS), and transmission electron microscopy (TEM) with high angle annular dark field (HAADF) imaging via scanning transmission electron microscopy (STEM) were employed for the characterization. Alloy specimens for TEM/STEM were prepared using site-specific focused ion beam (FIB) in-situ lift-out (INLO) technique. Despite the homogenization time and temperature, five different phases, namely fcc-Al solid solution, cubic-UAl3, orthorhombic-UAl4, hexagonal-U6Mo4Al43 and diamond cubic-UMo2Al20, were observed. Based on U-Al, U-Mo and Al-Mo binary phase diagrams, previously proposed U-Mo-Al isotherms, and the solidification microstructure of these alloys, the Al-rich region of the equilibrium ternary isotherm at 500?C was constructed. The fcc-Al solid solution, orthorhombic-UAl4, and diamond cubic-UMo2Al20, which were determined to be the equilibrium phases in 85.7Al-11.44U-2.86Mo and 87.5Al-10U-2.5Mo alloys.

E. Perez; A. Ewh; J. Liu; B. Yuan; D. D. Keiser, Jr.; Y. H. Sohn

2009-11-01

109

Evaluating Zn, Al and Al-Zn coatings on carbon steel in a special atmosphere  

SciTech Connect

This paper presents a comparative evaluation of Al, Zn and Al-Zn coatings on carbon steel exposed to a coastal-marine atmosphere. It is a very aggressive atmosphere with high wind velocities (corrosion-erosion rate = 1.4 mm/year for ASTM 1029 steel). A metallized zinc coating with a pore sealer was also evaluated. ISO and ASTM standards were used for the evaluation. After a two-year exposure the best performance was achieved by the Al and Al rich alloy (85%Al-15%Zn) with some damage of the coatings. But the Zn metallized coating, with a pore sealer, did not show signs of damage.

Troconis de Rincon, O.; Delgado, R.; Lopez, B. [Univ. del Zulia, Maracaibo (Venezuela). Centro de Estudios de Corrosion; Uruchutu, J. [Univ. de Cuernavaca (Mexico)

1999-11-01

110

Atomistic Modeling of RuAl and (RuNi) Al Alloys  

NASA Technical Reports Server (NTRS)

Atomistic modeling of RuAl and RuAlNi alloys, using the BFS (Bozzolo-Ferrante-Smith) method for alloys is performed. The lattice parameter and energy of formation of B2 RuAl as a function of stoichiometry and the lattice parameter of (Ru(sub 50-x)Ni(sub x)Al(sub 50)) alloys as a function of Ni concentration are computed. BFS based Monte Carlo simulations indicate that compositions close to Ru25Ni25Al50 are single phase with no obvious evidence of a miscibility gap and separation of the individual B2 phases.

Gargano, Pablo; Mosca, Hugo; Bozzolo, Guillermo; Noebe, Ronald D.; Gray, Hugh R. (Technical Monitor)

2002-01-01

111

Reassessment of NiAl and Ni-Fe-Al solidus temperatures  

Microsoft Academic Search

Solidus temperatures of the B2 NiAl phase have been determined by high-temperature differential thermal analysis for binary\\u000a melt compositions NixAl100?x\\u000a (45xyNi50?yAl50 (0?y?50). It was shown that the melting temperature of the stoichiometric Ni50Al50 phase is 1681 °C, which is 43 K higher than some literature data. The solidus line at the Ni-rich side of the Ni-Al phase\\u000a diagram exhibits a

H. Bitterlich; W. Löser; L. Schultz

2002-01-01

112

Anodic behavior of Al and the alloys Al-In and Al-In-Ga in aluminum-air batteries  

Microsoft Academic Search

The anodic behavior of aluminum and the alloys Al-In and Al-In-Ga was tested under the operating conditions of aluminum-air batteries. The tests were conducted in an aqueous solution of 2 M NaCl, and the results obtained were compared with the results obtained from a special test of these alloys as the anode in a standard electrochemical cell. Significant results and

D. M. Drazic; A. R. Despic; S. K. Zecevic

1979-01-01

113

Reaction of Ti and Ti-Al alloys with alumina  

NASA Technical Reports Server (NTRS)

The reaction of single-crystal Al2O3 with pure Ti and Ti-Al alloys with different Al concentrations was examined in the temperature range of 1173 to 1573 K. Significant reaction occurred between Al2O3 and the Ti-Al alloys with Al concentrations lower than that corresponding to the gamma-TiAl phase. The reaction mechanism was determined to be simultaneous diffusion of Al and atomic oxygen from Al2O3 into Ti and the Ti-Al alloys.

Misra, Ajay K.

1991-01-01

114

Thermal diffusion in Ni/Al multilayer  

SciTech Connect

Two Ni/Al multilayers deposited by ion beam sputtering of nominal design [Ni(200A)/Al(100A)] Multiplication-Sign 5 and [Ni(50A)/Al(227A)] Multiplication-Sign 5 on Si substrates were annealed at 200 Degree-Sign C. As-deposited and annealed samples were characterized by x-ray diffraction (XRD) and x-ray reflectometry (XRR). The effort was to study the path of alloying in the above two multilayers of same elements but of opposite stoichiometric ratio. We find distinct differences in alloying of these samples.

Swain, M.; Bhattacharya, D.; Singh, S.; Basu, S. [Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085 (India); Gupta, M. [UGC-DAE-Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India)

2013-02-05

115

[A strategy to develop effective ALS therapy].  

PubMed

In the early 1990s, a number of major events took place in the history of the treatment and science of ALS. A cause of familial ALS, the mutation of superoxide dismutase 1, was discovered and very shortly after, an animal model expressing the human SOD1 mutation for familial ALS was generated. Around the same time, the first medication for the treatment of ALS, riluzole, was approved. Clinical neurologists started to focus more attention on quality of life and standardizing care for patients with ALS, including devising approaches for presenting and discussing the diagnosis, using aggressive symptomatic treatments, and developing a multidisciplinary care system. Since then, nutritional and respiratory care has markedly improved. Respiratory care for those with terminal ALS in Japan has been distinct and perhaps more effective compared to the rest of the world, and this unique experience must be broadly published and shared with others. In 1999, the ALS Treatment Guidelines were published by the American Academy of Neurology and are now under revision. A monitoring system to determine the impact the Guidelines had on actual patient care has taught us that caregivers have only slowly accepted the recommendation to improve quality of care. The team approach, using a multidisciplinary care system from diagnosis to the end of life, is essential to improve care for both the patient and family. Coinciding with the progress in ALS treatment, basic science and translational research also produced dramatic progress in ALS drug discovery. Over the past 15 years, more than 25 potential drugs have been tested in randomized controlled trials. Despite this progress, we have no medications other than riluzole. Although it may be true that ALS research is in its early stages compared to research in other diseases with no cure--it is probably behind cancer research by at least 20 or 30 years--we need to drastically change our approach to drug development. At a national level, we need to create a strong, cohesive team with support from a number of funding agencies, oversight from a regulatory agency, and investigators who all think "outside the box." In addition, we should obtain ideas and suggestions from accomplished experts outside of the field of ALS and put competition aside as we work together to develop strategic plans for the ALS drug development that is essential to beat this devastating disease. PMID:17447525

Mitsumoto, Hiroshi

2007-04-01

116

Wetting of polycrystalline SiC by molten Al and Al-Si alloys  

NASA Astrophysics Data System (ADS)

The wetting of ?-SiC by molten Al and Al-Si alloys was investigated using a dispensed sessile drop method in a high vacuum. In the Al-SiC system, representative wetting stages were identified. The liquid spreading was initially controlled by the deoxidation of the SiC surface and then by the formation of Al4C3 at the interface. The intrinsic contact angle for molten Al on the polycrystalline ?-SiC surface was suggested to be lower than 90? provided that the oxide films covering the Al and SiC surfaces were removed, i.e., the system is partial wetting in nature. An increase in the Si concentration in liquid Al weakened the interfacial reaction but improved the final wettability. The role of the Si addition on the wetting was presumably attributed to its segregation at the interface and the formation of strong chemical bonds with the SiC surface.

Cong, Xiao-Shuang; Shen, Ping; Wang, Yi; Jiang, Qichuan

2014-10-01

117

High quality AlGaN grown on ELO AlN/sapphire templates  

NASA Astrophysics Data System (ADS)

The defect structure and the homogeneity of 1-3 µm thick AlxGa1-xN layers grown on epitaxially laterally overgrown (ELO) AlN on patterned AlN/sapphire templates have been investigated in dependence on the miscut direction of the c-plane sapphire substrates, the etching depth into the sapphire and the Al concentration. It was found that shallowly etched AlN/sapphire templates with a 0.25° miscut toward the a-plane provide a smooth surface of ELO AlN and therefore a good Al homogeneity in the overgrown Al0.8Ga0.2N layer. The threading dislocation density in these layers is as low as 5×108 cm-2.

Zeimer, U.; Kueller, V.; Knauer, A.; Mogilatenko, A.; Weyers, M.; Kneissl, M.

2013-08-01

118

Calcium platinum aluminium, CaPtAl  

PubMed Central

A preliminary X-ray study of CaPtAl has been reported previously by Hulliger [J. Alloys Compd (1993), 196, 225–228] based on X-ray powder diffraction data without structure refinement. With the present single-crystal X-ray study, we confirm the assignment of the TiNiSi type for CaPtAl, in a fully ordered inverse structure. All three atoms of the asymmetric unit have .m. site symmetry. The structure features a ? 3[AlPt] open framework with a fourfold coordination of Pt by Al atoms and vice versa. The Ca atoms are located in the large channels of the structure. PMID:22064850

Kenfack Tsobnang, Patrice; Fotio, Daniel; Ponou, Simeon; Fon Abi, Charles

2011-01-01

119

Nominalization in Q'anjob'al (Maya)  

E-print Network

Q’anjob’al typically makes a rigid distinction between transitive and intransitive verb inflections. Transitive verbs cross-reference their subjects with an ergative prefix while intransitive verbs cross-reference their ...

Mateo, Pedro

2010-01-01

120

COMMUNICATION MatthiasTreier et al.  

E-print Network

COMMUNICATION MatthiasTreier et al. Anaromaticcouplingmotiffor two-dimensionalsupramolecular architectures ISSN1359-7345 www.rsc.org/chemcomm Number38|14October2008|Pages4509­4648 Chemical Communications

Hone, James

121

12th Annual ALS Users' Association Meeting  

SciTech Connect

Science took the front seat as 219 Advanced Light Source (ALS) users and staff gathered on Monday and Tuesday, October 18 and 19 for the twelfth annual users' meeting. The bulk of the meeting was dedicated to reports on science at the ALS. Packed into two busy days were 31 invited oral presentations and 80 submitted poster presentations, as well as time to visit 24 vendor booths. The oral sessions were dedicated to environmental science, chemical dynamics, biosciences, magnetic materials, and atomic and molecular science. In addition, there was an ALS highlights session that emphasized new results and a session comprising highlights from the young scientists who will carry the ALS into the future.

Robinson, Arthur L.

1999-12-17

122

Analysis of al-2 Mutations in Neurospora  

PubMed Central

The orange pigmentation of the fungus Neurospora crassa is due to the accumulation of the xanthophyll neurosporaxanthin and precursor carotenoids. Two key reactions in the synthesis of these pigments, the formation of phytoene from geranylgeranyl pyrophosphate and the introduction of ? cycles in desaturated carotenoid products, are catalyzed by two domains of a bifunctional protein, encoded by the gene al-2. We have determined the sequence of nine al-2 mutant alleles and analyzed the carotenoid content in the corresponding strains. One of the mutants is reddish and it is mutated in the cyclase domain of the protein, and the remaining eight mutants are albino and harbor different mutations on the phytoene synthase (PS) domain. Some of the mutations are expected to produce truncated polypeptides. A strain lacking most of the PS domain contained trace amounts of a carotenoid-like pigment, tentatively identified as the squalene desaturation product diapolycopene. In support, trace amounts of this compound were also found in a knock-out mutant for gene al-2, but not in that for gene al-1, coding for the carotene desaturase. The cyclase activity of the AL-2 enzyme from two albino mutants was investigated by heterologous expression in an appropriately engineered E. coli strain. One of the AL-2 enzymes, predictably with only 20% of the PS domain, showed full cyclase activity, suggesting functional independence of both domains. However, the second mutant showed no cyclase activity, indicating that some alterations in the phytoene synthase segment affect the cyclase domain. Expression experiments showed a diminished photoinduction of al-2 transcripts in the al-2 mutants compared to the wild type strain, suggesting a synergic effect between reduced expression and impaired enzymatic activities in the generation of their albino phenotypes. PMID:21818281

Diaz-Sanchez, Violeta; Estrada, Alejandro F.; Trautmann, Danika; Limon, M. Carmen; Al-Babili, Salim; Avalos, Javier

2011-01-01

123

Analysis of al-2 mutations in Neurospora.  

PubMed

The orange pigmentation of the fungus Neurospora crassa is due to the accumulation of the xanthophyll neurosporaxanthin and precursor carotenoids. Two key reactions in the synthesis of these pigments, the formation of phytoene from geranylgeranyl pyrophosphate and the introduction of ? cycles in desaturated carotenoid products, are catalyzed by two domains of a bifunctional protein, encoded by the gene al-2. We have determined the sequence of nine al-2 mutant alleles and analyzed the carotenoid content in the corresponding strains. One of the mutants is reddish and it is mutated in the cyclase domain of the protein, and the remaining eight mutants are albino and harbor different mutations on the phytoene synthase (PS) domain. Some of the mutations are expected to produce truncated polypeptides. A strain lacking most of the PS domain contained trace amounts of a carotenoid-like pigment, tentatively identified as the squalene desaturation product diapolycopene. In support, trace amounts of this compound were also found in a knock-out mutant for gene al-2, but not in that for gene al-1, coding for the carotene desaturase. The cyclase activity of the AL-2 enzyme from two albino mutants was investigated by heterologous expression in an appropriately engineered E. coli strain. One of the AL-2 enzymes, predictably with only 20% of the PS domain, showed full cyclase activity, suggesting functional independence of both domains. However, the second mutant showed no cyclase activity, indicating that some alterations in the phytoene synthase segment affect the cyclase domain. Expression experiments showed a diminished photoinduction of al-2 transcripts in the al-2 mutants compared to the wild type strain, suggesting a synergic effect between reduced expression and impaired enzymatic activities in the generation of their albino phenotypes. PMID:21818281

Díaz-Sánchez, Violeta; Estrada, Alejandro F; Trautmann, Danika; Limón, M Carmen; Al-Babili, Salim; Avalos, Javier

2011-01-01

124

Semiconducting Al transition-metal quasicrystals  

NASA Astrophysics Data System (ADS)

We report on a class of icosahedral aluminum transition-metal (Al-TM) alloys with true semiconducting behavior. Our description of the structure of these icosahedral quasicrystals is based on the six-dimensional Katz-Gratias-Boudard (KGB) model of the face-centered-icosahedral (fci) quasicrystal and its rational approximants. The shell structure of the atomic surfaces in perpendicular space defines the chemical order of aluminum and transition-metal (TM) atoms leading to semiconducting transport properties. In transition-metal aluminides the hybridization between the Al(s,p) and transition-metal d orbitals is responsible for the formation of a semiconducting gap in the electronic spectrum. We have analyzed the electronic charge distribution and observed an enhanced charge density along the Al-TM bonds that is characteristic of covalent bonding. The existence of an energy gap in the electronic spectrum at or in the vicinity of the Fermi level is explicitly demonstrated for several low-order approximants in the hierarchy of Fibonacci approximants which converges to the icosahedral quasicrystals of the fci class, to which also the i-AlPdRe belongs. We predict existence of truly semiconducting quasicrystalline 1/1-approximants. Our results also lead to the prediction of the existence of new semiconducting quasicrystals with specified Al-TM compositions. The possibility of the existence of a semiconducting band gap suggests an explanation for the anomalously high resistivity of the icosahedral AlPdRe quasicrystals. We demonstrate that substitutional defects violating the ideal Al-TM ordering predicted by the KGB model lead to the formation of localized states in the band gap. A real sample of i-AlPdRe thus seems to be a semiconductor with a band gap filled by the localized states.

Kraj?í, M.; Hafner, J.

2003-10-01

125

Modeling of precipitation in Al alloys  

SciTech Connect

Objective was the development of a computational model of precipitation from a supersaturated alloy solid solution. The model is based on the formalism of chemical-reaction-rate theory combined with classical descriptions of precipitate thermodynamic properties and a mean-field treatment of diffusion-limited growht and coarsening. For the case of precipitation of Al{sub 3}Sc in supersaturated Al-Sc alloys, it is demonstrated how the model can be used to calculate number densities and size distributions of precipitates as a function of aging time and temperature, including effects of continuous cooling and thermally generated point defects. Application of the model to a specific alloy system requires knowledge of diffusion data, point defect energetics, and thermodynamic properties for bulk phases and interphase interfaces. For interfaces and point defects, thermodynamic data can be difficult to measure and reliable values of defect free energies are often unavailable. For this reason, part of the efforts were devoted to applying semiempirical and first-principles atomistic techniques to the calculation of interfacial and point-defect thermodynamic properties. This report discusses applications for interphase interfaces in the Al-Ag, Al-Sc, and Al-Li alloy systems. We also describe atomistic work aimed at understanding the energetics of vacancy clusters in Al. These clusters serve as sinks for isolated vacancies during aging and their growth can lead to more complex defects, such as dislocation loops, that act as heterogeneous nucleation sites.

Asta, M.; Foiles, S.M.; Wolfer, W.G. [Sandia National Labs., Livermore, CA (United States)] [and others

1996-10-01

126

Air blast characteristics of laminated al and NI-AL casings  

NASA Astrophysics Data System (ADS)

Air blast characteristics of Al and Ni-Al laminated materials were experimentally investigated in a 23 m3 closed chamber. Ni and Al foils, 50 to 100 micrometers in thickness, were rolled and compacted to form a cylindrical casing with a density of 95% TMD through an explosive formation technique. Charges were prepared using 2 kg C4 explosive packed in the laminated casing to a metal-explosive mass ratio of 1.75. The blast pressure history measured on the chamber wall showed a double-shock front structure with a precursor shock followed by the primary blast. The front peak pressure for the Ni-Al cased charge reaches 1.5-2 times that of the Al cased, consistent with the larger fireball recorded for the Ni-Al cased. The long time quasi-static explosion pressure (QSP) from the Ni- Al cased charge is 0.8 of that of the Al cased, due to half of Al mass in the Ni-Al.

Zhang, Fan; Ripley, Robert; Wilson, William

2012-03-01

127

Formation and large cryogenic magnetocaloric effect of HoAl2/Al2O3 nanocapsules  

NASA Astrophysics Data System (ADS)

HoAl2/Al2O3 nanocapsules with a core of HoAl2 and a shell of amorphous Al2O3 have been synthesized. The formation of the rare-earth compound nanocapsules can be ascribed to the different melting points and the optimal proportions of Ho and Al atoms during the arc-discharging process. Furthermore, the formation of the Al2O3 shell protects the rare-earth atoms from serious oxidation. The HoAl2/Al2O3 nanocapsules display superparamagnetic properties between the blocking temperature of 6 K and the Curie temperature of 26 K. The absolute value of the magnetic-entropy change in the HoAl2/Al2O3 nanocapsules rapidly increases with the decrease in temperature and reaches 14.7 J kg-1 K-1 at 3 K for a magnetic-field change from 0 to 70 kOe. As a result, this new type of nanocapsule may be applied, in the temperature range studied, in cryogenic magnetic-refrigerator devices.

Liu, X. G.; Li, B.; Geng, D. Y.; Shi, C. X.; Yang, F.; Kang, D. J.; Zhang, Z. D.

2009-02-01

128

Optical microcavities and enhanced electroluminescence from electroformed Al-Al2O3-Ag diodes  

NASA Astrophysics Data System (ADS)

Electroluminescence (EL) and electron emission into vacuum (EM) occur when a non-destructive dielectric breakdown of Al-Al2O3-Ag diodes, electroforming, results in the development of a filamentary region in which current-voltage (I-V) characteristics exhibit voltage-controlled negative resistance. The temperature dependence of I-V curves, EM, and, particularly, EL of Al-Al2O3-Ag diodes with anodic Al2O3 thicknesses between 12 nm and 30 nm, has been studied. Two filters, a long-pass (LP) filter with transmission of photons with energies less than 3.0 eV and a short-pass (SP) filter with photon transmission between 3.0 and 4.0 eV, have been used to characterize EL. The voltage threshold for EL with the LP filter, VLP, is ˜1.5 V. VLP is nearly independent of Al2O3 thickness and of temperature and is 0.3-0.6 V less than the threshold voltage for EL for the SP filter, VSP. EL intensity is primarily between 1.8 and 3.0 eV when the bias voltage, VS ? 7 V. EL in the thinnest diodes is enhanced compared to EL in thicker diodes. For increasing VS, for diodes with the smallest Al2O3 thicknesses, there is a maximum EL intensity, LMX, at a voltage, VLMX, followed by a decrease to a plateau. LMX and EL intensity at 4.0 V in the plateau region depend exponentially on Al2O3 thickness. The ratio of LMX at 295 K for a diode with 12 nm of Al2O3 to LMX for a diode with 25 nm of Al2O3 is ˜140. The ratio of EL intensity with the LP filter to EL intensity with the SP filter, LP/SP, varies between ˜3 and ˜35; it depends on Al2O3 thickness and VS. Enhanced EL is attributed to the increase of the spontaneous emission rate of a dipole in a non-resonant optical microcavity. EL photons interact with the Ag and Al films to create surface plasmon polaritons (SPPs) at the metal-Al2O3 interfaces. SPPs generate large electromagnetic fields in the filamentary region of the electroformed Al-Al2O3-Ag diode, which then acts as an optical microcavity. A model is proposed for electronic processes in electroformed Al-Al2O3-Ag diodes.

Hickmott, T. W.

2013-12-01

129

Tin/Al sub 2 O sub 3 /TiAlOn composite  

SciTech Connect

The present invention pertains to novel improved density ceramic composites of TiN/Al2O3/TiAlON in which there is no spinel and no AlN, but alpha-alumina, titanium nitride, and titanium aluminum oxynitride. In general, the improved density TiN/Al2O3/TiAlON ceramic composites of the invention are prepared by: adding aluminum isobutoxide (Al(O-iBu)3) to a refluxing mixture of deionized water and formic acid at elevated temperatures to obtain an aluminum sol; casting the slurry in molds; drying the cast material and calcining it at about 600 C; screening the calcined material to minus 200 mesh; pressing pellets at about 10 KPsi, isostatically pressing them at about 40 KPsi; and sintering the pellets below 1,700 C to obtain sintered bodies having densities greater than about 4.2 g/cc.

Han, K.

1990-04-02

130

Effects of Al(III) and Nano-Al13 Species on Malate Dehydrogenase Activity  

PubMed Central

The effects of different aluminum species on malate dehydrogenase (MDH) activity were investigated by monitoring amperometric i-t curves for the oxidation of NADH at low overpotential using a functionalized multi-wall nanotube (MWNT) modified glass carbon electrode (GCE). The results showed that Al(III) and Al13 can activate the enzymatic activity of MDH, and the activation reaches maximum levels as the Al(III) and Al13 concentration increase. Our study also found that the effects of Al(III) and Al13 on the activity of MDH depended on the pH value and aluminum speciation. Electrochemical and circular dichroism spectra methods were applied to study the effects of nano-sized aluminum compounds on biomolecules. PMID:22163924

Yang, Xiaodi; Cai, Ling; Peng, Yu; Li, Huihui; Chen, Rong Fu; Shen, Ren Fang

2011-01-01

131

Analog resistive switching behavior of Al/Nb2O5/Al device  

NASA Astrophysics Data System (ADS)

Resistive switching effects in metal–insulator–metal (MIM) structures are strongly influenced by the electrode materials. In this work a platinum-free symmetric Al/Nb2O5/Al device is compared to a device with platinum bottom electrode. For the device with the platinum bottom electrode, filamentary based resistive switching with good data retention was observed up to 125 °C. For the Al/Nb2O5/Al device, an area dependent pure electronic based resistive switching was observed. Electron trapping at the bottom electrode interface is responsible for the observed analog switching behavior which makes an Al/Nb2O5/Al device suitable for neuromorphic applications.

Mähne, H.; Wylezich, H.; Hanzig, F.; Slesazeck, S.; Rafaja, D.; Mikolajick, T.

2014-10-01

132

Theoretical studies of Ni/sub 3/Al and NiAl with impurities  

SciTech Connect

Intermetallic compound has been extensively studied because of their superior properties in strength, low creep rate, and high melting point. But most of the systems have room temperature ductility problems, like Ll/sub 2/ and B2 compounds. Both Ll/sub 2/ Ni/sub 3/Al and B2 NiAl exhibit intergranular fracture mode. Understanding grain boundaries in these materials is of particular importance since intergranular fracture limits the applicability of these otherwise promising material. In an effort trying to understand the fracture mechanism, we have used embedded atom potentials to study the properties of Ni/sub 3/Al and NiAl. We also consider the effect of boron, sulfur, and nickel segregation on the strength of grain boundaries in Ni/sub 3/Al and NiAl. 22 refs., 2 figs.

Chen, S.P.; Voter, A.F.; Boring, A.M.; Albers, R.C.; Hay, P.J.

1988-01-01

133

?-phase formation in NiAl and Ni2Al alloys  

NASA Astrophysics Data System (ADS)

The phase stability of bcc-like NiAl and Ni2Al with respect to phase transformations into the ? phase is examined by first-principles, full-potential, linear muffin-tin orbital method (FPLMTO), band-structure calculations. In agreement with experiment we find that bcc-like NiAl is stable, whereas Ni2Al is unstable. We have also performed some calculations in slightly disordered phases, and find that the disordering tends to inhibit the transformation. This supports the suggestion that a combined displacive/ordering transformation mechanism is involved in the phase transformations of the Ni2Al system. Calculated lattice parameters and the degree of internal shuffling of atoms for the ordered Ni2Al phase were found to be in excellent agreement with the experiment

Sanati, M.; Albers, R. C.; Pinski, F. J.

2001-06-01

134

The lowest ionization potentials of Al2  

NASA Technical Reports Server (NTRS)

Potential curves for the lowest two electronic states (X 2 sigma g + and A 2 pi u) of Al2(+) were computed using complete active space SCF/multireference CI wave functions and large Gaussian basis sets. The lowest observable vertical ionization potential (to Al2(+) X 2 sigma g +) of the Al2 X 3 pi u ground state is calculated to occur around 6.1 eV, in excellent agreement with the experimental range of 6.0 to 6.42 eV obtained in recent cluster ionization studies by Cox and co-workers. The second vertical ionization potential (to Al2(+) A 2 pi u) occurs near 6.4 eV, also within the experimental range. The adiabatic IP of 5.90 eV is in good agreement with the value of 5.8 to 6.1 eV deduced by Hanley and co-workers from the difference in thresholds between collision induced dissociation processes of Al3(+). The computed IP values are somewhat larger than those deduced from branching ratios in cluster fragmentation experiments by Jarrold and co-workers. The observation of an ionization threshold below 6.42 eV is shown to be incompatible with an Al2 ground electronic state assignment of 3 sigma g -, but the separation between the two lowest states of Al2 is so small that it is likely that both are populated in the experiments, so that this does not provide unambiguous support for the recent theoretical assignment of the ground state as 3 pi u.

Bauschlicher, Charles W., Jr.; Barnes, Leslie A.; Taylor, Peter R.

1988-01-01

135

The Stability of Al 11Sm3 (Al4Sm) Phases in the Al-Sm Binary System  

SciTech Connect

The relative stability of Al{sub 11}Sm{sub 3} (Al{sub 4}Sm) intermetallic phases was experimentally investigated through a series of heat treatments followed by microstructural, microchemical, and X-ray diffraction (XRD) analyses. The principal findings are that the high-temperature tetragonal phase is stable from 1655 to 1333 K and that the low-temperature orthorhombic phases, {alpha} and {gamma}, have no range of full stability but are metastable with respect to the crystalline Al and Sm reference states down to 0 K. Thermodynamic modeling is used to describe the relative energetics of stable and metastable phases along with the associated two-phase mixtures. Issues regarding transition energetics and kinetics are discussed.

S.H.Zhou; R.E. Napolitano

2007-06-01

136

Two-Phase (TiAl+TiCrAl) Coating Alloys for Titanium Aluminides  

NASA Technical Reports Server (NTRS)

A coating for protecting titanium aluminide alloys, including the TiAl gamma + Ti3Al (alpha(sub 2)) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C. is disclosed. This protective coating consists essentially of titanium, aluminum. and chromium in the following approximate atomic ratio: Ti(41.5-34.5)Al(49-53)Cr(9.5-12.5)

Brady, Michael P. (Inventor); Smialek, James L. (Inventor); Brindley, William J. (Inventor)

1998-01-01

137

The embrittlement of Al-Zn-Mg and Al-Mg alloys by water vapor  

Microsoft Academic Search

Al4.5Zn1.5Mg and Al5Mg were reacted in water-vapor saturated air (WVSA) at 120°C and tensile tested. After an initial loss of ductility with exposure time, probably caused by hydrogen embrittlement of the grain boundaries, between 15 hours and 25 hours exposure the mechanical properties of Al4.5Zn1.5Mg improved, this effect being due both to a reduced corrosion activity of the grain boundaries

C. D. S. Tuck

1985-01-01

138

Martensitic transformation in CVD NiAl and (Ni,Pt)Al bond coatings  

Microsoft Academic Search

The martensitic phase transformation in single-phase ?-NiAl and (Ni,Pt)Al coatings was investigated. After isothermal exposure to 1150 °C for 100 h, the ? phase in both types of coatings was transformed to a martensite phase during cooling to room temperature. Martensitic transformation was also observed in the (Ni,Pt)Al bond coat with and without a YSZ top layer after thermal cycling

Y Zhang; J. A Haynes; B. A Pint; I. G Wright; W. Y Lee

2003-01-01

139

Third-order elastic moduli of polycrystalline Al-Mg and Al-Cu alloys  

Microsoft Academic Search

The third-order elastic moduli of polycrystalline Al-rich Al-Mg and Al-Cu alloys are determined by measuring the changes in ultrasonic wave velocities under applied uniaxial stress. A solid-state pulse interferometer sensitive to a few parts per million for the relative velocity measurement was used. Pressure derivatives of elastic moduli and Gruneisen gamma are evaluated from the measured second- and third-order moduli.

V. K. Raju; P. J. Reddy

1981-01-01

140

Plasma spray processing of Al 2O 3\\/AlN composite powders  

Microsoft Academic Search

A novel method is proposed to prepare Al2O3\\/AlN composite powders. The composite powders were synthesized by direct nitridation of Al2O3 powders in Ar\\/N2 plasma. The processing characteristics were studied. The results show that the particle size of the initial materials, the nitrogen plasma gas flow rate and the power of the plasma generator are important factors that influence the phase

L. H Cao; K. A Khor; L Fu; F Boey

1999-01-01

141

77 FR 73732 - In the Matter of Amendment of the Designation of al-Qa'ida in Iraq, aka Jam'at al Tawhid wa'al...  

Federal Register 2010, 2011, 2012, 2013

...Front, aka Jabhat al-Nusrah, aka Jabhet al-Nusra, aka The Victory Front, aka Al Nusrah Front for the People of the Levant...the Secretary of State hereby amends the 2004 designation of al-Qa'ida in Iraq as a foreign terrorist...

2012-12-11

142

High temperature deformation of NiAl and CoAl  

NASA Technical Reports Server (NTRS)

The high temperature mechanical properties of the aluminides are reviewed with respect to their potential as high temperature structural materials. It is shown that NiAl and CoAl are substantially stronger than the pure metals Ni and Co at high temperatures and approach the strength of some superalloys, particularly when those superalloys are tested in "weak" directions. The factors that limit and control the high temperature strengths of NiAl and CoAl are examined to provide a basis for the development of intermetallic alloys of this type.

Nix, W. D.

1982-01-01

143

Deformation microstructures of [gamma]-TiAl in the Ti-46Al-2V alloy  

SciTech Connect

The intermetallic compound [gamma]-TiAl (L1[sub 0]) is potentially useful for elevated temperature structural applications. It has significant strength and reasonable ductility at high temperatures, but its applications are seriously affected by poor room temperature ductility. The deformation mechanisms of [gamma]-TiAl have been the topics of several papers in recent years. The effect of V addition on the deformation microstructures of [gamma]-TiAl in the two-phase ([alpha][sub 2] + [gamma]) Ti-46Al-2V (at.%) alloy at various temperature is reported in this paper.

Das, S.; Chaudhuri, K. (Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering)

1995-01-15

144

HYDROGEN ADSORPTION ON ?-TiAl (001) AND Ni/TiAl (001) SURFACES  

NASA Astrophysics Data System (ADS)

In this paper, we present first principles calculations of the energetic, electronic and magnetic properties of the variant termination of TiAl (001) and Ni/TiAl (001) surfaces with and without hydrogen atoms. The calculations have been performed within the density functional theory using full-potential linearized augmented plane wave method. The generalized gradient approximation (GGA) is utilized as the exchange-correlation energy. The octahedral site is the stable absorption site of H atom in the ?-TiAl system. This absorption reduces the cohesive energy of ?-TiAl system due to increase in the lattice constant. The surface energy for both TiAl (001) terminations is calculated. The stable adsorption site of H atoms on the variant termination of TiAl (001) surface is performed. The adsorption energy of hydrogen on Ti is more energetic than that on Al. The adsorption of H atom on both terminations of H/Ni/TiAl (001) is more preferable at the bridge site. The adsorption energies are enhanced on Ni atom due to the contraction between d-Ni bands and TiAl substrate band.

Mubarak, A. A. Karim; Alelaimi, Mahmoud

2014-04-01

145

Microsample testing of single crystalline Ti-52 at% Al and Ti-55.5 at% Al  

SciTech Connect

Dislocation activity in two-phase commercial TiAl alloys occurs most readily in the {gamma}-TiAl phase, and measurements of the CRSS of single crystalline {gamma}-TiAl provides a solid foundation for understanding the mechanical performance of these alloys. Single crystals of {gamma}-TiAl with greater than 54.5 at% Al have been grown using the optical float zone crystal growing technique, but single crystals with lower Al content, closer to that of commercial alloys, have not. In the present study, polycrystalline ingots of Ti-52 at% Al have been heat treated to form very large grains, and microsample tensile specimens, which have a nominal gage cross-section of 250{micro}m x 300{micro}m, a gage length of 250{micro}m and an overall length of 3 mm, have been machined from within single grains. Microsample high-temperature stress-strain curves for Ti-55.5 at% Al single crystals oriented along the [001] and [010] are presented. Tensile test results for Ti-52 at% Al tested at 1,073K along the[{bar 2}37], [{bar 1}73] and [{bar 3}44] orientations will also be discussed.

Zupan, M.; Dimiduk, D.M.; Hemker, K.J.

1999-07-01

146

Mechanical properties of Al and Al alloys and their relationship to interconnection reliability  

NASA Astrophysics Data System (ADS)

Pure Al, Al-3 wt %Si, and Al-15 at. % C films are characterized macroscopically in terms of yield stress and hardness and microscopically in terms of a grain structure to investigate the effects of Si and carbon additives to modify mechanical properties of the Al matrix. A theory is presented to estimate the yield stress of metal films. The experimental method is based on laser interferometer measurements of the varied substrate curvature involved with thermal treatment of a film-substrate composite. It is shown that carbon addition increases yield stress and hardness of Al, whereas Si addition decreases these properties. Carbon addition suppresses grain growth by 450 °C annealing as small as about 0.04 ?m. Reliability tests on Al and Al-alloy interconnects revealed that increased yield stress improves resistance against failures due to the stress at high temperatures and high current densities, but degrades resistance against cycled thermal shock. The double layered Al-C/Al structure was highly resistant against both thermal and current stress.

Ozawa, Kiyoshi

1993-01-01

147

Solid state reaction of Al and Zr in Al/Zr multilayers: A calorimetry study  

SciTech Connect

The exothermic, solid state reaction of Al and Zr has been studied in thick Al/Zr multilayers using Differential Scanning Calorimetry and X-ray diffraction. The multilayer samples were magnetron sputter deposited into highly textured alternate layers of Al and Zr with nominal composition Al{sub 3}Zr. The samples used in this study were 47{mu}m thick with a 427{Angstrom} period. When samples were isochronally scanned from 25 to 725C, a large exotherm at {approximately}350C was followed by one or two smaller exotherms at {approximately}650C. The first exotherm is dominated by a diffusion based reaction of Al and Zr that produces two phases in isochronal scans: amorphous Al-Zr and cubic Al{sub 3}Zr, and two additional phases in isothermal anneals: Al{sub 2}Zr and tetragonal Al{sub 3}Zr. The exothermic heat from this multi-phase reaction is measured using isochronal scans and isothermal anneals, and the heat flow is analyzed using a 1-D diffusion based model. An average activation energy and a diffusion constant are determined. In the isothermal scans, the total exothermic heat increases linearly with {radical}time, and layer thicknesses vary linearly with heat.

Blobaum, K.J.; Weihs, T.P.; Barbee, T.W. Jr.; Wall, M.A.

1995-04-14

148

Elastic and piezoelectric properties of AlN and LiAlO2 single crystals.  

PubMed

We have successfully grown high-quality AlN piezoelectric single crystal using the sublimation technique. Transparent crack-free boules of approximately 15 mm in diameter and 25 mm in length along the [0001] direction were obtained, with coloring from amber to dark brown depending on growth temperature. Full sets of material parameters of grown AlN and commercially available LiAlO(2) bulk crystals were measured at room temperature. Temperature coefficients of the material parameters of LiAlO(2) were also obtained in a temperature range from -70 to +50 degrees C. PMID:20378443

Sotnikov, Andrey; Schmidt, Hagen; Weihnacht, Manfred; Smirnova, Elena; Chemekova, Tatiana; Makarov, Yuri

2010-04-01

149

Possible Involvement of Al-Induced Electrical Signals in Al Tolerance in Wheat.  

PubMed Central

The relationship between Al-induced depolarization of root-cell transmembrane electrical potentials (Em) and Al tolerance in wheat (Triticum aestivum L.) was investigated. Al exposure induced depolarizations of Em in the Al-tolerant wheat cultivars Atlas and ET3, but not in the Al-sensitive wheat cultivars Scout and ES3. The depolarizations of Em occured in root cap cells and as far back as 10 mm from the root tip. The depolarization was specific to Al3+; no depolarization was observed when roots were exposed to the rhizotoxic trivalent cation La3+. The Al-induced depolarization occurred in the presence of anion-channel antagonists that blocked the release of malate, indicating that the depolarization is not due to the electrogenic efflux of malate2-. K+-induced depolarizations in the root cap were of the same magnitude as Al-induced depolarizations, but did not trigger malate release, indicating that Al-induced depolarization of root cap cell membrane potentials is probably linked to, but is not sufficient to trigger, malate release. PMID:12223834

Papernik, L. A.; Kochian, L. V.

1997-01-01

150

The PtAl- and PtAl2- anions: Theoretical and photoelectron spectroscopic characterization  

NASA Astrophysics Data System (ADS)

We report a joint photoelectron spectroscopic and theoretical study of the PtAl- and PtAl2- anions. The ground state structures and electronic configurations of these species were identified to be C?v, 1?+ for PtAl-, and C2v, 2B1 for PtAl2-. Structured anion photoelectron spectra of these clusters were recorded and interpreted using ab initio calculations. Good agreement between theory and experiment was found. All experimental features were successfully assigned to one-electron transitions from the ground state of the anions to the ground or excited states of the corresponding neutral species.

Zhang, Xinxing; Ganteför, Gerd; Bowen, Kit H.; Alexandrova, Anastassia N.

2014-04-01

151

Magnetron sputtered nc-Al/alpha-Al2O3 nanocomposite thin films for nonvolatile memory application.  

PubMed

In this paper, we developed nc-Al/a-Al2O3 nanocomposite thin films using magnetron sputtering. The nc-Al/a-Al2O3 films were sputtered on p-type Si substrates from pure Al target in gas mixture of Ar and O2. X-ray photoelectron spectroscopy and high resolution transmission electron microscope studies confirm that the nanocrystalline Al are embedded in amorphous Al2O3 matrix thus nc-Al/ a-Al2O3 nanocomposite forms. This nanocomposite thin film exhibits memory effect as a result of charge trapping. PMID:19916417

Li, Yibin; Zhang, Sam; Liu, Y; Chen, T P; Sritharan, Thirumany; Xu, Cong

2009-07-01

152

Sintering Behavior and Mechanical Properties of NiAl, Al2O3, and NiAl-Al2O3 Composites  

NASA Astrophysics Data System (ADS)

It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite's stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

Chmielewski, M.; Nosewicz, S.; Pietrzak, K.; Rojek, J.; Strojny-N?dza, A.; Mackiewicz, S.; Dutkiewicz, J.

2014-08-01

153

Photoemission from Al Alloys during Tensile Deformation  

NASA Astrophysics Data System (ADS)

We report simultaneous measurements of strain and photoelectron emission intensity from high purity Al (1350), Al-Mg (5052), Al-Mn (3003), Al-Cu (2024) and Al-Mg-Si (6061) alloys under uniaxial tension due to pulsed excimer laser radiation (248-nm). The photoemission signals are sensitive to deformation-induced changes in surface morphology, including the formation of slip lines and slip bands. In the early stages of deformation (strain Â¡Ü 0.03), the photoemission intensity increases gradually in a nonlinear fashion. Depending on sample composition and heat treatment, the photoemission intensity subsequently grows linearly until the accumulated strain reaches about 0.20. Finally, the photoemission intensity increases parabolically until failure. The onset of strain localization corresponds to the transition from linear to parabolic growth. A constitutional model incorporating microstructure evolution and work-hardening during tensile deformation is proposed to qualitatively interpret the growth of the photoemission signals as a function of strain. The photoemission signals from the tested alloys are interpreted in terms of the effect of surface treatment, work function, microstructure, and composition on the development of dislocation structures during deformation.

Cai, Mingdong; Langford, Stephen; Levine, Lyle; Dickinson, Thomas

2004-03-01

154

First-principle study of adhesion, wetting and bonding on Al/Al3V(001) interface  

NASA Astrophysics Data System (ADS)

The adhesion, wetting, and bonding on fcc-Al(001)/D022-Al3V(001) interface were investigated using density functional calculations. Considering different terminations of Al3V(001) (Al- and Al + V-terminated) and stacking sites (center-, hollow- and top-sites), six Al/Al3V(001) models were calculated. For the models with same stacking site, Al + V-terminated model has larger work of adhesion (Wad) than the Al-terminated one. For the models with same termination, the work of adhesion decreases, and the interface energy (?int) increases as the order of top-, bridge- and center-sites. Al-terminated-center-sited and Al + V-terminated-center-sited models are more stable among six models. After complete structure relaxation, both models have the same epitaxial stacking style. Therefore, the both models can be regarded as of the same and most stable one (noted as CSI model), but separating along Al-Al and Al-Al+V inter-planes. Based on the perfect wetting and strong adhesion in CSI model, the heterogeneous nucleation of ?-Al on Al3V(001) was interpreted in terms of crystallography and thermodynamics. The interfacial bonding was discussed with analysis of valence electron density distribution and partial density of states (PDOS). The bonding is mainly contributed from AlV covalent bonds and AlAl metallic interactions.

Li, Jian; Qi, Yuning; Zhang, Ming; Zhou, Yong; Li, Xiao

2014-06-01

155

Early Solar Nebula Condensates with Canonical, Not Supracanonical, Initial 26Al/27Al Ratios  

NASA Astrophysics Data System (ADS)

The short-lived radionuclide 26Al existed throughout the solar nebula 4.57 Ga ago, and the initial abundance ratio (26Al/27Al)0, as inferred from magnesium isotopic compositions of calcium-aluminum-rich inclusions (CAIs) in chondritic meteorites, has become a benchmark for understanding early solar system chronology. Internal mineral isochrons in most CAIs measured by secondary ion mass spectrometry (SIMS) give (26Al/27Al)0 ~ (4-5) × 10-5, called "canonical." Some recent high-precision analyses of (1) bulk CAIs measured by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), (2) individual CAI minerals and their mixtures measured by laser-ablation MC-ICPMS, and (3) internal isochrons measured by multicollector (MC)-SIMS indicated a somewhat higher "supracanonical" (26Al/27Al)0 ranging from (5.85 ± 0.05) × 10-5 to >7 × 10-5. These measurements were done on coarse-grained Type B and Type A CAIs that probably formed by recrystallization and/or melting of fine-grained condensate precursors. Thus the supracanonical ratios might record an earlier event, the actual nebular condensation of the CAI precursors. We tested this idea by performing in situ high-precision magnesium isotope measurements of individual minerals in a fine-grained CAI whose structures and volatility-fractionated trace element abundances mark it as a primary solar nebula condensate. Such CAIs are ideal candidates for the fine-grained precursors to the coarse-grained CAIs, and thus should best preserve a supracanonical ratio. Yet, our measured internal isochron yields (26Al/27Al)0 = (5.27 ± 0.17) × 10-5. Thus our data do not support the existence of supracanonical (26Al/27Al)0 = (5.85-7) × 10-5. There may not have been a significant time interval between condensation of the CAI precursors and their subsequent melting into coarse-grained CAIs.

MacPherson, G. J.; Bullock, E. S.; Janney, P. E.; Kita, N. T.; Ushikubo, T.; Davis, A. M.; Wadhwa, M.; Krot, A. N.

2010-03-01

156

ALS and Frontotemporal Dysfunction: A Review  

PubMed Central

Though once believed to be a disease that was limited to the motor system, it is now apparent that amyotrophic lateral sclerosis (ALS) may be associated with cognitive changes in some patients. Changes are consistent with frontotemporal dysfunction, and may range from mild abnormalities only recognized with formal neuropsychological testing, to profound frontotemporal dementia (FTD). Executive function, behavior, and language are the most likely areas to be involved. Screening helpful in detecting abnormalities includes verbal or categorical fluency, behavioral inventories filled out by the caregiver, and evaluation for the presence of depression and pseudobulbar affect. Patients with cognitive dysfunction have shortened survival and may be less compliant with recommendations regarding use of feeding tubes and noninvasive ventilation. Evolving knowledge of genetic and pathological links between ALS and FTD has allowed us to better understand the overlapping spectrum of ALS and FTD. PMID:22919484

Achi, Eugene Y.; Rudnicki, Stacy A.

2012-01-01

157

Textures of Ta/Al multilayer films  

NASA Astrophysics Data System (ADS)

Ta/Al multilayer films with a modulation wavelength of 7.0 nm were grown using magnetron sputtering. The Bragg ?-2? scan pattern and the plate film photograph of x-ray diffraction reveal that the sample has Ta(110) and A1(111) axial textures with a mosaic spread of about ±5° and coherency strains. The structure change of the multilayer sample after annealing at 550 °C for 2 h is determined by the plate film photography of x-ray diffraction to study the thermal stability. It is found that after annealing a large amount of Ta and Al atoms at the interfaces are combined into TaAl3 with [(202)+(002)] textures.

Yuan, X. Y.; Wu, Z. Q.; Hu, A.; Jiang, S. S.; Qiu, Y.; Khatanova, N. A.; Ilyushin, R. S.

1993-04-01

158

Stress granules as crucibles of ALS pathogenesis  

PubMed Central

Amyotrophic lateral sclerosis (ALS) is a fatal human neurodegenerative disease affecting primarily motor neurons. Two RNA-binding proteins, TDP-43 and FUS, aggregate in the degenerating motor neurons of ALS patients, and mutations in the genes encoding these proteins cause some forms of ALS. TDP-43 and FUS and several related RNA-binding proteins harbor aggregation-promoting prion-like domains that allow them to rapidly self-associate. This property is critical for the formation and dynamics of cellular ribonucleoprotein granules, the crucibles of RNA metabolism and homeostasis. Recent work connecting TDP-43 and FUS to stress granules has suggested how this cellular pathway, which involves protein aggregation as part of its normal function, might be coopted during disease pathogenesis. PMID:23629963

King, Oliver D.

2013-01-01

159

[Al-Biruni--a universal scientist].  

PubMed

Al-Biruni's was of Persian descent. He was born in Horesmiya and had studied mathematics, history and medicine. Acquiring knowledge from these sciences, he wrote an outstanding work on chronology of several nations and devoted it to Ziyarit ruler Kabus. He made a chronological overview of calendars from many nations, including Persians, Greeks, Egyptians, Jews, Melkitian and Nestorian Christians, Sabeyaans as well as the old Arabs. Data presented in the work, according to the later authors, were taken from very reliable sources. He was contemporary of Ibn-Sina, and thanks to their friendship, they have discussed very much miscellaneous topics. He belonged to the group of scholars, taken by Gaznevian Soultan Mahmud to a long journey to India. Afterwards Al-Biruni wrote and published detailed work "Description of India"--a work on cultural history of India. Due to excellent abilities of Al-Biruni as a philosopher and scholar, there are still significant and reliable notes about buddhistic philosophy, structure of castes and Brahmans' life style. In this Al-Biruni's masterpiece, there are many comparative analysis of Suffism and certain Indian philosophical methods. Al-Biruni's most important work is "Pharmacopoeia"--"Kitab al-saydala", which brilliantly describes all medicaments. This work has been published in many languages. He also wrote few works on astronomy and astrology. In those works he has explained some astrological events through scientific approach in a such peculiar way that nobody has ever explained before. He was also interested in sciences like geology, mineralology, geography, mathematics, psychology and many others. PMID:10386051

Kujundzi?, E; Masi?, I

1999-01-01

160

Mathematik als Geisteswissenschaft Der Mathematikschädigung dialogisch vorbeugen  

NASA Astrophysics Data System (ADS)

Ursprünglich wollte ich Architekt werden getreu den Vorbildern von Vater und Großvater. Darum zeichnete ich bereits als neunjähriges Kind Pläne von Häusern in der Art, wie ich sie oft zu sehen bekam. Ein ausgemustertes Holzdreieck mit einem rechten und zwei halben rechten Winkeln war das einzige Konstruktionswerkzeug, das ich damals besaß und mit dem ich mich ans Werk machte. Zuerst einmal war da natürlich ein Rechteck als Grundriss des Hauses zu zeichnen: Eine Seite, ein rechter Winkel, die zweite Seite, wieder ein rechterWinkel, die dritte Seite in gleicher Länge wie die erste und dann der dritte rechte Winkel, dessen letzter Schenkel die vierte Seite gab.

Gallin, Peter

161

Machining performance of Ti–Al–Si–N coated inserts  

Microsoft Academic Search

Ti–Al–Si–N quaternary coating has recently been developed for industrial applications due to its excellent machining performance. Here, we present a comparative research on Ti–Al–N single layer, Ti–Al–Si–N single layer, TiAlN–TiAlSiN bilayer and TiAlN\\/TiAlSiN multilayer coatings deposited onto cemented carbide substrates by cathodic arc evaporation. The incorporation of Si into the Ti–Al–N coating results in an increase in hardness and thermal

Li Chen; She Q. Wang; Yong Du; Shu Z. Zhou; Tie Gang; Ji C. Fen; Ke K. Chang; Yi W. Li; Xiang Xiong

2010-01-01

162

Synthesis of nanostructured AlN by solid state reaction of Al and diaminomaleonitrile  

SciTech Connect

The solid state reaction of diaminomaleonitrile (DAMN) with aluminum via both mechanochemical and thermal treatment routes was studied by X-ray diffraction and Fourier transform infrared spectroscopy. During the milling process, the reaction starts with the deammoniation of the DAMN molecules, followed by the formation of nanostructured AlN powder as the main solid product after milling for 7 h. The reactivity of the mixed powder was also investigated during the conventional thermal treatment process using differential scanning calorimetry, derivative thermogravimetry and thermogravimetric analysis. The results reveal that DAMN starts to polymerize at 192 Degree-Sign C by the elimination of the amine groups. Furthermore, increasing the annealing temperature leads to the formation of a nitrogen-containing carbonaceous material with the structure similar to non-crystalline carbon. However, no evidence for the formation of AlN was observed in the annealed samples even at temperatures as high as the Al melting point. - Graphical abstract: AlN nanoparticles obtained after milling of Al and diaminomaleonitrile (DAMN) for 12 h. Highlights: Black-Right-Pointing-Pointer Solid state reaction of diaminomaleonitrile (DAMN) with Al was studied via mechanochemical and thermal treatment routs. Black-Right-Pointing-Pointer Nanocrystalline AlN was successfully synthesized by the mechanochemical process. Black-Right-Pointing-Pointer The C/N material was formed by polymerization of DAMN during the thermal treatment process. Black-Right-Pointing-Pointer No reaction between DAMN and Al was detected during the thermal treatment method.

Rounaghi, S.A., E-mail: s.a.rounaghi@gmail.com [Department of Materials Engineering, Ferdowsi University of Mashhad. P.O. Box no. 91775-1111, Mashhad (Iran, Islamic Republic of); IFW Dresden, Institut fuer Komplexe Materialien, Postfach 27 01 16, Dresden D-01171 (Germany); Eshghi, H., E-mail: heshghi@ferdowsi.um.ac.ir [Department of Chemistry, Ferdowsi University of Mashhad. P.O. Box no. 91775-1436, Mashhad (Iran, Islamic Republic of); Kiani Rashid, A.R.; Vahdati Khaki, J. [Department of Materials Engineering, Ferdowsi University of Mashhad. P.O. Box no. 91775-1111, Mashhad (Iran, Islamic Republic of)] [Department of Materials Engineering, Ferdowsi University of Mashhad. P.O. Box no. 91775-1111, Mashhad (Iran, Islamic Republic of); Samadi Khoshkhoo, M.; Scudino, S. [IFW Dresden, Institut fuer Komplexe Materialien, Postfach 27 01 16, Dresden D-01171 (Germany)] [IFW Dresden, Institut fuer Komplexe Materialien, Postfach 27 01 16, Dresden D-01171 (Germany); Eckert, J. [IFW Dresden, Institut fuer Komplexe Materialien, Postfach 27 01 16, Dresden D-01171 (Germany) [IFW Dresden, Institut fuer Komplexe Materialien, Postfach 27 01 16, Dresden D-01171 (Germany); TU Dresden, Institut fuer Werkstoffwissenschaft, Dresden D-01062 (Germany)

2013-02-15

163

AlAskA Justice Forum University of AlAskA AnchorAge  

E-print Network

AlAskA Justice Forum University of AlAskA AnchorAge A PUblicAtion of the JUstice center Fall 2008 to Alaska State Troopers Marny Rivera, Andr� B. Rosay, Darryl S. Wood, Greg Postle, and Katherine Te violence is an undeniable urban and rural problem in Alaska and the nation. Detailed data on domestic

Pantaleone, Jim

164

University of AlAskA AnchorAge AlAskA Justice Forum  

E-print Network

University of AlAskA AnchorAge AlAskA Justice Forum A PUblicAtion of the JUstice center Fall 2013 in Alaska and nationally (page 2). � An update on the work of the Alaska Prisoner Reentry Task Force (page 5 Collateral Consequences and Reentry in Alaska: An Update Deborah Periman "Our legal system has created

Pantaleone, Jim

165

University of AlAskA AnchorAge AlAskA Justice Forum  

E-print Network

University of AlAskA AnchorAge AlAskA Justice Forum A PUblicAtion of the JUstice center Spring 2013 respected professionals have retired after lengthy careers working with troubled youth inAlaska. For this issue of the Alaska Justice Forum, we asked three of these professionals to provide reflections from

Pantaleone, Jim

166

University of AlAskA AnchorAge AlAskA Justice Forum  

E-print Network

University of AlAskA AnchorAge AlAskA Justice Forum A PUblicAtion of the JUstice center Summer 2013 Vol. 30, No. 2 Please see Alcohol, page 13 Reducing Sales of Alcohol to Underage Persons in Alaska within a few hours) in the past month, more than one quarter of youth in public high schools in Alaska

Pantaleone, Jim

167

^27Al-NMR Study of the Spinel Compound CoAl2O4  

NASA Astrophysics Data System (ADS)

CoAl2O4, a geometrically frustrated magnet, is believed to be located in the vicinity of a quantum melting point of the AFM ordered state. In CoAl2O4, magnetic frustration originates from Co^2+(S = 3/2) spins on the tetrahedral A-site via non-magnetic Al ions occupying the octahedral B-site. To study the magnetic properties of CoAl2O4 from a microscopic point of view, we have carried out ^27Al-NMR measurements using a well-characterized powder sample of CoAl2O4. The temperature dependence of the magnetic susceptibility ? shows a broad peak around 15 K and does not show any difference in zero-field-cooled and field-cooled measurements. ^27Al-NMR spectra at 9.3 MHz (H = 0.84 T) show seven peaks characterized by quadrupolar splitting with ?Q= 0.55 MHz at temperatures above 10 K. Below 10 K, the spectrum broadens suddenly. We also observe a peak of 1/T1 of ^27Al at 10 K. These NMR results clearly indicate magnetic ordering at 10 K, although ? does not exhibit any signature of long-range magnetic ordering.

Roy, Beas; Pandey, Abhishek; Johnston, David C.; Furukawa, Yuji

2013-03-01

168

ccsd00004518, Precipitation kinetics of Al 3 Zr and Al 3 Sc in  

E-print Network

ccsd­00004518, version 2 ­ 21 Mar 2005 Precipitation kinetics of Al 3 Zr and Al 3 Sc in aluminum/Si#18;ege, 31-33, rue de la F#19;ed#19;eration, 75752 Paris cedex 15, France Abstract Precipitation dynamics, a mesoscopic modeling technique which describes the various stages of homogeneous precipitation

169

Research Note: Hassan al-Turabi, Osama bin Laden, and Al Qaeda in Sudan  

Microsoft Academic Search

This research note explores the events and circumstances surrounding Osama bin Laden's stay in Sudan from 1991 to 1996. In particular, it discusses the role that the Sudanese politician, Hassan al-Turabi may have played in the development of bin Laden and al Qaeda. It draws particular attention to the role of the Popular Arab and Islamic Congress (PAIC) in the

Max Taylor; Mohamed E. Elbushra

2006-01-01

170

Bakker is in Canada al op stage geweest als de begeleider van  

E-print Network

2828 actIeve stUDeNt Bakker is in Canada al op stage geweest als de begeleider van toen iets nieuws ploeteren naar `het dak der aarde'. "Bij iedere bocht moest ik bijkomen", bekent Bakker. "En die sherpa: bij onder- zoeken naar bijvoorbeeld de vocht- huishouding van de nieren of, in het geval van Bakker

Twente, Universiteit

171

Characterization of nanophase Al-oxide/Al powders by electron energy-loss spectroscopy.  

PubMed

Al nanoparticles were prepared by the inert gas condensation method. After passivation with oxygen and air exposure we obtained a powdered sample of an Al-oxide/Al nanocomposite material. In the present paper we describe the use of the electron energy-loss spectroscopy (EELS) technique in a transmission electron microscope to characterize such nanostructured powders compared with a microcrystalline commercial aluminium foil. Energy-filtered images showed the presence of an alumina overlayer of approximately 4 nm covering the aluminium nanoparticles (23 nm in diameter). EELS analysis enabled us to determine the total amount of Al2O3 and metallic Al and the structure of the alumina passivation overlayer in the sample. In particular, the extended energy-loss fine structure analysis of the data showed a major presence of Al tetrahedrally coordinated with oxygen in the alumina passivation layer of Al nanoparticles instead of the octahedral coordination found for a conventional Al foil. This surprising effect has been attributed to the nanoscopic character of the grains. The analysis of the electron-loss near-edge structure also determines the presence of a certain degree of aggregation in this kind of powdered sample as result of the coalescence of the nanocrystalline grains. The procedure presented here may have the potential to solve other problems during characterization of nanostructured materials. PMID:9767485

Fernández; Sánchez-López; Caballero; Martin; Vacher; Ponsonnet

1998-08-01

172

Melting, Processing, and Properties of Disordered Fe-Al and Fe-Al-C Based Alloys  

NASA Astrophysics Data System (ADS)

This article presents a part of the research work conducted in our laboratory to develop lightweight steels based on Fe-Al alloys containing 7 wt.% and 9 wt.% aluminum for construction of advanced lightweight ground transportation systems, such as automotive vehicles and heavy-haul truck, and for civil engineering construction, such as bridges, tunnels, and buildings. The melting and casting of sound, porosity-free ingots of Fe-Al-based alloys was accomplished by a newly developed cost-effective technique. The technique consists of using a special flux cover and proprietary charging schedule during air induction melting. These alloys were also produced using a vacuum induction melting (VIM) process for comparison purposes. The effect of aluminum (7 wt.% and 9 wt.%) on melting, processing, and properties of disordered solid solution Fe-Al alloys has been studied in detail. Fe-7 wt.% Al alloy could be produced using air induction melting with a flux cover with the properties comparable to the alloy produced through the VIM route. This material could be further processed through hot and cold working to produce sheets and thin foils. The cold-rolled and annealed sheet exhibited excellent room-temperature ductility. The role of carbon in Fe-7 wt.% Al alloys has also been examined. The results indicate that Fe-Al and Fe-Al-C alloys containing about 7 wt.% Al are potential lightweight steels.

Satya Prasad, V. V.; Khaple, Shivkumar; Baligidad, R. G.

2014-09-01

173

modified source procedure of Kirwan et al. [6] and Wais et al. [7] because source memory is neither necessary nor  

E-print Network

modified source procedure of Kirwan et al. [6] and Wais et al. [7] because source memory is neither predicts recollection. J. Neurosci. 28, 10541­10548 7 Wais, P.E. et al. (2010) In search of recollection

Wixted, John T.

174

Al/sub 2/O/sub 3/ adherence on CoCrAl alloys  

SciTech Connect

Adherence of protective oxides on NiCrAl and CoCrAl superalloys has been promoted by a dispersion of a highly oxygen reactive element or its oxide being produced within the protection system. Two aspects of this subject are investigated here: the use of Al/sub 2/O/sub 3/ as both the dispersion and protective oxide; and the production of an HfO/sub 2/ dispersion while simultaneously aluminizing the alloy. It was found that an Al/sub 2/O/sub 3/ dispersion will act to promote the adherence of an external scale of Al/sub 2/O/sub 3/ to a degree comparable to previously tested dispersions and an HfO/sub 2/ dispersion comparable to that produced by a Rhines pack treatment is produced during aluminization.

Kingsley, L.M.

1980-04-01

175

In situ microscopy of rapidly heated nano-Al and nano-Al/WO3 thermites  

NASA Astrophysics Data System (ADS)

The initiation and reaction mechanism of nano-Al and nano-Al thermites in rapid heating environments is investigated in this work. A semiconductor-based grid/stage was used, capable of in situ heating of a sample from room temperature to 1473 K, and at a rate of 106 K/s, inside an electron microscope. Nano-Al was rapidly heated in a transmission electron microscope, and before and after images indicate that the aluminum migrates through the shell, consistent with a diffusion-based mechanism. A nano-Al/WO3 composite was then heated in a scanning electron microscope. The results indicate that a reactive sintering mechanism is occurring for the nano-Al/WO3 thermite, as the products are found to be in surface contact and significantly deformed after the heating pulse.

Sullivan, Kyle T.; Chiou, Wen-An; Fiore, Richard; Zachariah, Michael R.

2010-09-01

176

Characteristics of vertically stacked Nb/Al/AlN/Nb Josephson junctions  

NASA Astrophysics Data System (ADS)

Vertically stacked Josephson junctions have been fabricated with Nb/Al/AlN as a base unit. The reactively sputtered AlN layer is deposited much more quickly than the lengthy thermal oxidation of Al. AlN is therefore a favorable candidate for stacked junctions consisting of many layers. Lift-off patterning the junctions avoids the problem of anodizing or etching through many layers. The superconducting layer thickness is chosen to be small with respect to the London penetration depth to allow coupling of the magnetic field in the adjacent insulating layers. Current versus voltage characteristics of these devices will be presented. In addition, critical current as a function of applied magnetic field will be presented.

Maglic, S. R.; Thomas, C. D.; Song, S. N.; Ulmer, M. P.; Ketterson, J. B.

1996-03-01

177

Temperature dependence of the activity of Al in dilute Ni(Al) solid solutions  

SciTech Connect

Activities of dilute Al solid solutions in Ni are determined from a first-principles approach. Both thermal lattice vibration and electronic contributions to free energies are considered and compared. Vibrational contributions tend to dominate the temperature dependencies of the free energies, though electron thermal effects are significant. Calculations show opposing temperature trends for the formation enthalpies and entropies, leading to a partial cancellation of their role in the overall energetics. Nevertheless, their remaining temperature effects are strong. Over the temperature range, 400 KAl activity coefficient varies by 15 orders of magnitude, due to the relative strength of Al-Ni and Al-Al bonds. The Ni activity coefficient only varies less than 4% over the same range. Calculational results compare well with available experimental data. The thermodynamic principles elucidated from the calculations are used to provide a fundamental interpretation.

Jiang Yong; Smith, J. R. [Delphi Research Labs, Shelby Township, Michigan 48315 (United States); Evans, A. G. [University of California, Santa Barbara, California 93106 (United States)

2006-12-01

178

27Al-NQR Study on Novel Phase Transition in CeOs2Al10  

NASA Astrophysics Data System (ADS)

We have performed 27Al-NQR measurements in CeOs2Al10 which exhibits a novel phase transition at T0=29 K The NQR parameters determined for all the Al sites in ambient pressure were compared with those in CeRu2Al10 with T0=27 K and CeFe2Al10 with no phase transition. The distinct NQR splitting just below T0=32.5 K under pressure 0.66 GPa ensures an enhancement of T0 and a homogeneous transition. Despite the increase of T0, the nuclear spin-lattice relaxation rate 1/Tl is suppressed over whole range of temperature than in ambient pressure. The characteristic features of no critical slowing down at T0 and of the remarkable decrease of 1/T1T starting at T > T0 become prominent under pressure, suggesting an approach to Kondo semiconductor in a valence fluctuation regime.

Matsumura, M.; Inagaki, T.; Kato, H.; Nishioka, T.; Tanida, H.; Sera, M.

2012-12-01

179

Formation of gamma'-Ni3Al via the Peritectoid Reaction: gamma plus beta (+Al2O3) equals gamma'(+Al2O3)  

NASA Technical Reports Server (NTRS)

The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8 - 32 at.%Al and temperature range T = 1400 - 1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma'-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3) = gamma + beta (+ Al2O3), at 1640 plus or minus 1 K and a liquid composition of 24.8 plus or minus 0.2 at.%Al (at an unknown oxygen content). The {gamma + beta + Al2O3} phase field is stable over the temperature range 1633 - 1640 K, and gamma'-Ni3Al forms via the peritectiod, gamma + beta (+ Al2O3) = gamma'(+ Al2O3), at 1633 plus or minus 1 K. This behavior is inconsistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma'-Ni3Al phase field.

Copland, Evan

2008-01-01

180

Formation of gamma(sup prime)-Ni3Al via the Peritectoid Reaction: gamma + beta (+ Al2O3)=gamma(sup prime)(+ Al2O3)  

NASA Technical Reports Server (NTRS)

The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8-32 at.%Al and temperature range T=1400-1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma(sup prime)-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3)=gamma + Beta(+ Al2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%al (at an unknown oxygen content). The {gamma + Beta (+Al2O3} phase field is stable over the temperature range 1633-1640 K, and gamma(sup prime)-Ni3Al forms via the peritectoid, gamma + Beta (+ Al2O3)=gamma(sup prime) (+ Al2O3), at 1633 +/- 1 K. This behavior is consistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(sup prime)-Ni2Al phase field.

Copeland, Evan

2008-01-01

181

Kinematics of Disease Progression in Bulbar ALS  

ERIC Educational Resources Information Center

The goal of this study was to investigate the deterioration of lip and jaw movements during speech longitudinally in three individuals diagnosed with bulbar amyotrophic lateral sclerosis (ALS). The study was motivated by the need to understand the relationship between physiologic changes in speech movements and clinical measures of speech…

Yunusova, Yana; Green, Jordan R.; Lindstrom, Mary J.; Ball, Laura J.; Pattee, Gary L.; Zinman, Lorne

2010-01-01

182

Combating Al Qaeda's Splinters: Mishandling Suicide Terrorism  

Microsoft Academic Search

The past three years saw more suicide attacks than the last quarter century. Most of these were religiously motivated. While most Westerners have imagined a tightly coordinated transnational terrorist organization headed by Al Qaeda, it seems more likely that nations under attack face a set of largely autonomous groups and cells pursuing their own regional aims. Repeated suicide actions show

Scott Atran

2004-01-01

183

Kieffer et al., p. 1 Volcanologie -Volcanology  

E-print Network

Kieffer et al., p. 1 Volcanologie - Volcanology Reconnaissance de l'ignimbrite campanienne près du golfe d e Policastro (Italie), jusqu'à 150 km de sa zone d'émission. Implications volcanologiques et paléoenvironnementales. Recognition of the Campanian Ignimbrite near the Gulf of Policastro (Basilicata, Italy), 150 km

Boyer, Edmond

184

Al-Ghazali on Moral Education  

ERIC Educational Resources Information Center

Al-Ghazali (1058-1111 CE) is probably the most influential scholar, philosopher, theologian, legal expert, religious reformer and mystic in the history of Islam. Although he wrote extensively about education, and particularly about moral education, this writing is scattered through a number of different works and has received less scholarly…

Alavi, Hamid Reza

2007-01-01

185

Ternary Dy-Er-Al magnetic refrigerants  

DOEpatents

A ternary magnetic refrigerant material comprising (Dy{sub 1{minus}x}Er{sub x})Al{sub 2} for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant. 29 figs.

Gschneidner, K.A. Jr.; Takeya, Hiroyuki

1995-07-25

186

Al/Cl2 molten salt battery  

NASA Technical Reports Server (NTRS)

Molten salt battery has been developed with theoretical energy density of 5.2 j/kg (650 W-h/lb). Battery, which operates at 150 C, can be used in primary mode or as rechargeable battery. Battery has aluminum anode and chlorine cathode. Electrolyte is mixture of AlCl3, NaCl, and some alkali metal halide such as KCl.

Giner, J.

1972-01-01

187

AL ASK A SALMON alaska Salmon  

E-print Network

189 AL ASK A SALMON UNIT 13 alaska Salmon INTRODUCTION Pacific salmon have played an important and pivotal role in the history of Alaska. Salmon, along with mining, timber, and furs, were the keystone of residents and visitors to Alaska. Alaska native peoples and their heritage have a long, colorful bond

188

Al Magnifico Rettore Prof. Luigi Frati  

E-print Network

RS.U. scriventi comunicano con la presente che l'Assemblea R.S.U. del 02/02/2010 all'unanimità ha CCNL 2006/2009 in quanto in completo disaccordo nel metodo. Nel merito questa RSU CHIEDE ALL", fermo restando che questa RSU si riserva ulteriori proposte ed iniziative al riguardo. Cordiali saluti

Guidoni, Leonardo

189

(12) United States Patent Jalali et al.  

E-print Network

. Ultrafast analog-to-digital (A/D) conversion and digital-to-analog I/A) conversion are achieved,288,659 B1 Sep. 11, 2001 (54) DATA CONVERSION USING TIME MANIPULATION (75) Inventors: Bahrarn Jalali. ........................ .. 385/123 OTHER PUBLICATIONS Frankel et al., High--performancephotonic analogue--digital converter

Jalali. Bahram

190

Page et al. 1 POINTS IN QUESTION  

E-print Network

switches; Hafner & Nadler (1988), whose data require at most two host switches out of nine speciation events (Page, 1990); and his own studies (Barker, 1991) of 11 species of rock- #12;Page et al. 3 wallaby lice for which he found little evidence for cospeciation. It is hard to see how Barker arrived at his

Clayton, Dale H.

191

Diffusion bonding of ?-TiAl sheets  

Microsoft Academic Search

Using advanced ?-TiAl based alloys and various ingot and powder metallurgical routes, several aerospace engine components are now being developed. Further application of this material in the aerospace industry can only be implemented provided that successful joining and cost effective fabrication methods for this material are developed. In this context, diffusion bonding and superplastic forming of this material is considered

G. Çm; H. Clemens; R. Gerling; M. Koçak

1999-01-01

192

United States Patent [191 Jalali et al.  

E-print Network

use simple path length dilferences. either in free space or in ?bers to achieve true-time delay. See/1994 Glance et a]. ........................ 385/27 X OTHER PUBLICATIONS LJ Lembo et al.. "Low-Loss into a plurality of wavelength components. fed back on optically time-delayed feedback paths to a multiplexer which

Jalali. Bahram

193

(12) United States Patent Black et al.  

E-print Network

Alamos, New Mexico. After one test explos:ion, two atomic .bombs: were dropped on the Japanese cities of Hiroshima (6 Aug 1945) and Nagasaki (9 _:Aug 1945); the bomb dropped on - .Hiroshima was as. powerful as metric tons of TNT, that on equivalent to 22.000 metrie tOI"ll The USSR first detbnated al'l atomic 1949

Shamos, Michael I.

194

The Female Jihad: Al Qaeda's Women  

Microsoft Academic Search

When women carry out a suicide attack they undermine the idea of who and what a terrorist is. What is generally not realized is the extent to which women are involved in terrorism. The purpose of this article is to explore and to analyze the multifaceted roles of the women in the movement of Al Qaeda. The argument is that

Katharina Von Knop

2007-01-01

195

(12) United States Patent Reardan et al.  

E-print Network

patients receiving the drug. Abuses are identified by monitor- ing data in the database for prescription and method utilizes a central phannacy and database to track all prescriptions for a sensi- tive drug(12) United States Patent Reardan et al. (54) SENSITIVE DRUG DISTRIBUTION SYSTEM AND METHOD (75

Shamos, Michael I.

196

Ternary Dy-Er-Al magnetic refrigerants  

DOEpatents

A ternary magnetic refrigerant material comprising (Dy.sub.1-x Er.sub.x)Al.sub.2 for a magnetic refrigerator using the Joule-Brayton thermodynamic cycle spanning a temperature range from about 60K to about 10K, which can be adjusted by changing the Dy to Er ratio of the refrigerant.

Gschneidner, Jr., Karl A. (Ames, IA); Takeya, Hiroyuki (Ibaraki, JP)

1995-07-25

197

Al Eskan disease: Persian Gulf syndrome.  

PubMed

This article examines the potential relationship between Al Eskan disease and the Persian Gulf syndrome. Al Eskan disease, reported in Military Medicine in 1992, is a novel and previously unreported condition triggered by the exceptionally fine sand dust of the Central and Eastern Saudi Arabian peninsula. We repeat our study of the pathogenesis of Al Eskan disease to include the ultrastructural and microanalytical study of the sand, aerobiological studies of the Kingdom of Saudi Arabia, and the etiology, symptoms, and prevalence of the disease. We conclude that immunodepression resulting from the continued presence of sand particles less than 1 micron in diameter in the lungs and bodies of Persian Gulf veterans explains not only the symptoms of the hyperegic lung condition of phase I and the symptoms of phase II of Al Eskan disease, but also provides an important clue to a common factor in most cases of Persian Gulf illnesses. We include a discussion of most of the commonly suspected agents in the Persian Gulf syndrome. In this case, we conclude that each of these factors, such as oil well fires, old-world diseases, or depleted uranium, are probably adjuvant or contributing causes. The only common exposure that would lead to recognition of the Persian Gulf syndrome as a single medical condition, rather than a catch-all phrase for unrelated conditions, appears to be exposure to the ubiquitous, fine sand of the area, and a resulting immunosuppression that is aggravated by opportunistic infections and other nonmicrobial ailments. PMID:9002695

Korényi-Both, A L; Korényi-Both, A L; Juncer, D J

1997-01-01

198

The Rail Gun Muad Al Khaldi  

E-print Network

The Rail Gun Muad Al Khaldi Department of Electrical Engineering King Fahd University of Petroleum and Minerals Abstract- The rail gun is one of promising ways of launching projectiles. Recently, many. In this project, I am going to investigate the construction of electromagnetic rail guns, the way the function

Masoudi, Husain M.

199

Football team al-most snatches de-  

E-print Network

Inside &ONLINE Whew! Football team al- most snatches de- feat from the jaws of victory, but hangs by the museum. Thefinancialgiftisthesinglelargest donation in the history of the Har- vardArtMuseum. The Art to get their genome sequenced but also to share that information, along with their medical histories

200

Joint SSRTNet/ALS-MES Workshop report  

SciTech Connect

This joint workshop brought together experimentalists and theorists interested in synchrotron radiation and highlighted subjects relevant to molecular environmental science (MES). The strong mutual interest between the participants resulted in joint sessions on the first day, followed by more specialized parallel sessions on the second day. Held in conjunction with the Advanced Light Source (ALS) Users' Association Annual Meeting at the Lawrence Berkeley National Laboratory (Berkeley Lab), the Synchrotron Radiation Research Theory Network (SRRTNet) workshop was co-organized by Michel Van Hove (Berkeley Lab and University of California, Davis) and Andrew Canning (Berkeley Lab), while David Shuh (Berkeley Lab) organized the ALS-MES workshop. SRRTNet is a global network that promotes the interaction of theory and experiment (http://www.cse.clrc.ac.uk/Activity/SRRTnet). The ALS-MES project is constructing Beamline 11.0.2.1-2, a new soft x-ray beamline for MES investigations at photon energies from 75 eV to 2 keV, to provide photons for wet spectroscopy end stations and an upgraded scanning transmission x-ray microscope (STXM). The ALS-MES beamline and end stations will be available for users in the late fall of 2002.

Shuh, David; Van Hove, Michel

2001-11-30

201

Abrasive wear behavior of NiAl and NiAl-TiB2 composites  

SciTech Connect

Abrasive wear of NiAl and NiAl with 10, 20, and 40 vol.% TiB2 has been investigated using particles of different types and sizes. The addition of TiB2 as a particulate reinforcement to NiAl increases the hardness of the composite with respect to NiAl, and reduces the wear rate at all volume fractions on garnet and Al2O3 abrasives. Abrasion on SiC resulted in a minimum of the wear rate for the composite with 20% TiB2for most conditions. The composite with 40% TiB2consistently exhibited wear rates higher than the other composites when abraded on SiC. The only instance when the NiAl?40% TiB2 composite had a lower wear rate was when it was abraded on 16 and 37 mm SiC particles. The NiAl?TiB2 composite serves as a model system for studying the effect of reinforcement volume fraction on composite wear behavior and is discussed in terms of a composite wear model developed by Axe?n and Jacobson. q1999 Published by Elsevier Science S.A. All rights reserved.

Hawk, Jeffrey A.; Alman, David E.

1999-04-01

202

Thermodynamics on hydride vapor phase epitaxy of AlN using AlCl3 and NH3  

NASA Astrophysics Data System (ADS)

A thermodynamic analysis on hydride vapor phase epitaxy (HVPE) of AlN using AlCl3 and NH3 was performed. Regardless of the carrier gas used, partial pressures of Al-containing gaseous species [AlCl3, AlCl2, AlCl and (AlCl3)2] in equilibrium with AlN are significantly low in the temperature range of 500-1500 °C when the input V/III ratio is above 1. This means that the driving force for AlN growth (?PAl) becomes almost equal to the input partial pressure of AlCl3, which is quite different from HVPE of GaN. The good agreement between the calculated and experimental growth rates shows that HVPE of AlN is thermodynamically controlled.

Kumagai, Y.; Takemoto, K.; Kikuchi, J.; Hasegawa, T.; Murakami, H.; Koukitu, A.

203

Structure of vapor-phase deposited Al-Ge thin films and Al-Ge intermediate layer bonding of Al-based microchannel structures.  

SciTech Connect

Al-based high-aspect-ratio microscale structures (HARMS) are basic building blocks for all-Al microdevices. Bonding of Al-based HARMS is essential for device assembly. In this paper, bonding of Al-based HARMS to flat Al plates using Al-Ge thin film intermediate layers is investigated. The structure of sputter codeposited Al-Ge thin films was studied by high-resolution transmission electron microscopy as a function of the average film composition. The structure of the interface region between Al-based HARMS bonded to flat Al plates is studied by combining focused ion beam sectioning and scanning electron microscopy. An extended bonding interface region, {approx}100 {micro}m in width, is observed and suggested to result from liquidus/solidus reactions as well as diffusion of Ge in solid Al at the bonding temperature of 500 C. The extended interface region is suggested to be beneficial to Al-Al bonding via Al-Ge intermediate layers.

Mei, F. H.; Meng, W. J.; Hiller, J.; Miller, D. J.; Materials Science Division; Louisana State Univ.

2009-02-01

204

The effect of thermal annealing on the properties of Al-AlOx-Al single electron tunneling transistors  

NASA Astrophysics Data System (ADS)

The effect of thermal annealing on the properties of Al-AlOx-Al single electron tunneling transistors is reported. After treatment of the devices by annealing processes in forming gas atmosphere at different temperatures and for different times, distinct and reproducible changes of their resistance and capacitance values were found. According to the temperature regime, we observed different behaviors with regard to the resistance changes, namely the tendency to decrease the resistance by annealing at T=200 °C, but to increase the resistance by annealing at T=400 °C. We attribute this behavior to changes in the aluminum oxide barriers of the tunnel junctions. The good reproducibility of these effects with respect to the changes observed allows the proper annealing treatment to be used for postprocess tuning of tunnel junction parameters. Also, the influence of the annealing treatment on the noise properties of the transistors at low frequency was investigated. In no case did the noise figures in the 1/f regime show significant changes.

Scherer, H.; Weimann, Th.; Zorin, A. B.; Niemeyer, J.

2001-09-01

205

The embrittlement of Al-Zn-Mg and Al-Mg alloys by water vapor  

Microsoft Academic Search

Al4.5Zn1.5Mg and Al5Mg were reacted in water-vapor saturated air (WVSA) at 120?C and tensile tested. After an initial loss\\u000a of ductility with exposure time, probably caused by hydrogen embrittlement of the grain boundaries, between 15 hours and 25\\u000a hours exposure the mechanical properties of Al4.5Zn1.5Mg improved, this effect being due both to a reduced corrosion activity\\u000a of the grain boundaries

C. D. S. Tuck

1985-01-01

206

A crystalline oxide passivation for Al2O3/AlGaN/GaN  

NASA Astrophysics Data System (ADS)

In situ X-ray photoelectron spectroscopy and low energy electron diffraction are performed to study the formation of a crystalline oxide on the AlGaN surface. The oxidation of the AlGaN surface is prepared by annealing and remote N2 + O2 plasma pretreatments resulting in a stable crystalline oxide. The impact of the oxide on the interface state density is studied by capacitance voltage (C-V) measurements. It is found that a remote plasma exposure at 550 °C shows the smallest frequency dispersion. Crystalline oxide formation may provide a novel passivation method for high quality AlGaN/GaN devices.

Qin, Xiaoye; Dong, Hong; Kim, Jiyoung; Wallace, Robert M.

2014-10-01

207

When Validity Testing Lacks Validity: Comment on Levine et al.  

ERIC Educational Resources Information Center

Addresses each of the three main areas of Levine et al.'s (see this issue, CS 764 297) validity testing: mean differences in self-construals between Asians and Westerners and within individuals; priming experiments; and factor analysis of self-construal scales. Suggests that Levine et al.'s conclusions on crucial aspects of validity are untenable.…

Kim, Min-Sun; Raja, Narayan S.

2003-01-01

208

Precipitation mechanism of Al-substituted tobermorite using hydrothermal reaction  

NASA Astrophysics Data System (ADS)

We examined the addition of different crystal phases of alumina (?-Al2O3, ?-Al2O3) to slurries consisting of quartz and slaked lime for synthesis of Al-substituted tobermorite. XRD results showed that Al-substituted tobermorite formed after the reaction. It was clear that two kinds of Al-substituted tobermorite synthesized using different alumina crystal phases shows different morphologies. The difference in the reactivity of the Al2O3 had an influence in the hydrothermal reaction environment. The coordination number and chemical bonding-state of Al caused the different morphology of the tobermorite.

Abe, Kazuki; Maeda, Hirotaka; Ishida, Emile H.

2010-11-01

209

Post9\\/11 Evolution of Al Qaeda  

Microsoft Academic Search

\\u000a Before the 11 September 2001 attacks, Al-Qaeda had conducted an average of one attack every two years. Since then, Al-Qaeda\\u000a and its associated groups – what could be termed the Al-Qaeda movement – have mounted an attack, on average, every three months.\\u000a US successes in disrupting the Al-Qaeda network have also dispersed its operatives. Al-Qaeda organizers, operatives, financiers\\u000a and other

Rohan Kumar Gunaratna

2004-01-01

210

Enthalpies of formation of the Al–Ni intermetallic compounds  

Microsoft Academic Search

The Al–Ni system has been investigated by direct reaction calorimetry at high temperatures. Enthalpies of formation of the intermetallic compounds AlNi3, AlNi, Al3Ni2, and Al3Ni were determined and compared with the available experimental values based on calorimetric and emf measurements and with the calculated values from theoretical models. X-ray powder diffraction (XRD) and electron probe microanalysis (EPMA) were used to

F. Z Chrifi-Alaoui; M Nassik; K Mahdouk; J. C Gachon

2004-01-01

211

Stress evolution during ultrasonic Al ribbon bonding  

NASA Astrophysics Data System (ADS)

The present study reveals the stress distribution in the substrate during ultrasonic bonding. The deformations of the Si substrate, Al ribbon, and Al pad were numerically analyzed using a finite element method. Experimental observation of the interface using a highspeed video camera was also conducted to determine the actual interfacial slip amplitude. This amplitude becomes smaller than that of tool-tip with bonding time. It was suggested from the numerical simulations that frictional adhesion enhanced the friction force, resulting in an increase in the equivalent stress in the ribbon and pad. As a result, very large stresses occur in the substrate during ultrasonic bonding. These stresses evolve with the progress of ultrasonic bonding, i.e., frictional adhesion.

Ando, Masaya; Takashima, Kazumasa; Maeda, Masakatsu; Takahashi, Yasuo

2014-08-01

212

Al nanogrid electrode for ultraviolet detectors.  

PubMed

Optical properties of Al nanogrids of different pitches and gaps were investigated both theoretically and experimentally. Three-dimensional finite-difference time-domain simulation predicted that surface plasmons at the air/Al interface would enhance ultraviolet transmission through the subwavelength gaps of the nanogrid, making it an effective electrode on GaN-based photodetectors to compensate for the lack of transparent electrode and high p-type doping. The predicted transmission enhancement was verified by confocal scanning optical microscopy performed at 365 nm. The quality of the nanogrids fabricated by electron-beam lithography was verified by near-field scanning optical microscopy and scanning electron microscopy. Based on the results, the pitch and gap of the nanogrids can be optimized for the best trade-off between electrical conductivity and optical transmission at different wavelengths. Based on different cutoff wavelengths, the nanogrids can also double as a filter to render photodetectors solar-blind. PMID:21931425

Ding, G; Deng, J; Zhou, L; Gan, Q; Hwang, J C M; Dierolf, V; Bartoli, F J; Mazuir, C; Schoenfeld, W V

2011-09-15

213

Polarized Cold Neutron Capture in ^27Al  

NASA Astrophysics Data System (ADS)

The NPDGamma Experiment at the Spallation Neutron Source at ORNL is measuring the parity-odd correlation between the neutron spin and the direction of the emitted photon in the capture of cold neutrons on a 16-liter liquid parahydrogen target. The goal is to determine the strength of the weak nucleon-nucleon interaction. One of the main background contributions comes from the gamma rays produced by neutrons captured in the Al walls of the target vessel. To quantify this effect a commissioning experiment measured the parity-odd and parity-even asymmetries in the angular distribution of the gamma rays from the capture of polarized cold neutrons in a solid Al target. A status of the analysis of this experiment will be presented.

Balascuta, Septimiu

2013-04-01

214

Structure analysis of NiAl martensite  

SciTech Connect

Neutron elastic scattering experiments were performed in order to investigate the structure of the low temperature martensitic phase of Ni/sub 62.5/Al/sub 37.5/ alloy. The average structure analyzed from the integrated intensity was approximately described by the (5,/minus/2) structure proposed by Martynov et al. Small deviation from the exact (5,/minus/2) model in the positional parameters and the anomalously large Debye-Waller factor were obtained. The observed satellite profiles show asymmetrical broadening, and the peak positions shift from the regular reciprocal lattice points. These anomalous features of scattering profiles were tentatively interpreted by introducing spatial modulation of the strain and order parameters. 12 refs., 2 figs., 1 tab.

Noda, Y.; Shapiro, S.M.; Shirane, G.; Yamada, Y.; Fuchizaki, K.; Tanner, L.E.

1989-01-01

215

Berkeley Lab's ALS generates Femtosecond Synchrotron Radiation  

SciTech Connect

A Lawrence Berkeley National Laboratory (Berkeley Lab) team drawing its members from the Materials Sciences Division (MSD), the Center for Beam Physics in the Accelerator and Fusion Research Division, and the Advanced Light Source (ALS) has succeeded in generating 300-femtosecond pulses of synchrotron radiation at the ALS synchrotron radiation machine. Though this ''proof-of-principle'' experiment made use of visible light on a borrowed beamline, the laser ''time-slicing'' technique at the heart of the demonstration will soon be applied in a new bend-magnet beamline designed explicitly for the production of femtosecond pulses of X-rays to study long-range and local order in condensed matter with ultrafast time resolution. An undulator beamline based on the same technique has been proposed that will dramatically increase the flux and brightness.

Robinson, Arthur L.

2000-05-23

216

Self-aligned contact process for Nb/Al-AlO(x)/Nb Josephson junctions  

NASA Astrophysics Data System (ADS)

High quality Nb/Al-AlO(x)/Nb Josephson junctions have been fabricated by a novel process named the self-aligned contact process. After the definition of the junction area by a reactive ion etching (RIE) technique, the exposed Nb layer and the junction edge are anodized to protect against electrical shorts and an Al film is deposited as the etching stopper layer. After base electrode patterning by RIE, an insulation layer is deposited. The contact hole, with the diameter of the junction, for connecting a counter electrode and a wiring layer, can be made without registration because of the deposited Al film. The junctions fabricated by this process have exhibited excellent current-voltage characteristics (Vm = 70 mV at the critical current density of 1.8 kA/sq cm, Vm = 11 mV at the critical current density of 20 kA/sq cm.

Morohashi, S.; Hasuo, S.; Yamaoka, T.

1986-01-01

217

Rechargeable Al/Cl2 battery with molten AlCl4/-/ electrolyte.  

NASA Technical Reports Server (NTRS)

A molten salt system based on Al- and Cl2 carbon electrodes, with an AlCl3 alkali chloride eutectic as electrolyte, offers promise as a rechargeable, high energy density battery which can operate at a relatively low temperature. Electrode kinetic studies showed that the electrode reactions at the Al anode were rapid and that the observed passivation phenomena were due to the formation at the electrode surface of a solid salt layer resulting from concentration changes on anodic or cathodic current flow. It was established that carbon electrodes were intrinsically active for chlorine reduction in AlCl3-alkali chloride melts. By means of a rotating vitreous carbon disk electrode, the kinetic parameters were determined.

Holleck, G. L.; Giner, J.; Burrows, B.

1972-01-01

218

The evolution of Al-Azhar Street, Al-Qahira, Egypt  

E-print Network

The historic quarter of Cairo, al-Qahira, is going through a period intense transformation that is threatening the physical environment as well as the social and economic fabric of the city. The transformations taking place ...

Elkatsha, Markus Fawzy Fahmy

2000-01-01

219

Fabrication and properties of functionally graded NiAl/Al2O3 composites  

NASA Technical Reports Server (NTRS)

A modified sedimentation process was used in the production of a functionally gradient material (FGM), NiAl/Al2O3. A simple finite element model was used to guide our design and fabrication efforts by estimating residual stress states as a function of composite structure. This approach could lead to tailored designs that enhance or avoid specific residual stress states. Thermal cycling tests were factored into the model to predict time dependent or steady-state internal temperature and stress profiles. Four-point bend tests were conducted to establish the mechanical load-displacement behavior of a single interlayer FGM at room temperature, 800 and 1000 K. Room temperature bend strength of the FGM was 3-4 times that of the base NiAl. At elevated temperatures, composite fracture occurred in a gradual, noncatastrophic mode involving NiAl retardation of a succession of cracks originating in the alumina face.

Miller, D. P.; Lannutti, J. J.; Noebe, R. D.

1993-01-01

220

Fabrication of Fe-Al nanoparticles by selective oxidation of Fe-Al thin films  

PubMed Central

The possibility of a new technique for fabricating nanoparticles from thin films using selective oxidation in an atmosphere mixture of water vapor and hydrogen was investigated. Fe-5wt.%Al films were RF-sputtered and annealed in the atmosphere mixture at 900°C for up to 200 min, in order to oxidize aluminum selectively. Thermodynamics simulation showed that temperatures exceeding 800°C are necessary to prevent iron from being oxidized, as confirmed by the depth profile of XPS. As the annealing time increased, the morphology of the 200-nm Fe-Al films changed from the continuous to the discontinuous type; thus, particulate Fe-Al films formed after 100 min. The particulate 10- to 100-nm Fe-Al films showed super-paramagnetic behavior after the oxidation. Thus, a new technique for fabricating nanoparticles was successfully introduced using selective oxidation. PMID:23547781

2013-01-01

221

Synthesis and characterization of Al-Zn/Al2O3 nano-powder composites.  

PubMed

Composites consisting of Al-Zn/Al2O3 have been synthesized using high energy mechanical milling. High energy ball milling increases the sintering rate of the composite powder due to increased diffusion rate. Owing to the finer microstructure, the hardness of the sintered composite produced by using the mechanically milled nanocomposite powder is significantly higher than that of the sintered composite produced by using the as-mixed powder. The mean crystallite size of the matrix has been determined to be 27 nm by Scherrer equation using X-ray diffraction data. The powders have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and differential thermal analysis (DTA). The effect of high-energy ball milling and subsequent annealing on a mixture of Al and ZnO has also been investigated. DTA result show that the reaction temperature of Al-ZnO decreases with the increase in the ball milling time. PMID:17654976

Durai, T G; Das, Karabi; Das, Siddhartha

2007-06-01

222

Iron implantation in ?-Al2O3  

Microsoft Academic Search

Single crystal and ceramic ?-Al2O3 samples were implanted with 57Fe ions at different fluences, and different charge states of Fe were determined. The hyperfine interaction data showed that implanted ions are in Fe0, Fe2+, and Fe3+ states depending on the fluence. It is shown that after the annealing of the implanted sample in a 2.5CO 1CO2 atmosphere Fe spinel forms.

I. De´zsi; Cs. Fetzer

2008-01-01

223

this present b. He will als  

E-print Network

Room 00 PM3:0 efreshmen 2012 UMa THEMY T bstract: this present b. He will als cus on glo termediarie in lobal suppl he utilizes nmaking,g nal of Opera nalofProdu B,theJourna tScience,an ateProfesso Managem mization.Dr. l Research ernationalJ n,Mathema e. cholarin r of the nagement In2010, University Business

Nagurney, Anna

224

Al-ba?r al-mu??? war?? al-samaw?t wa-al-ar?: Jewish and Christian cosmogonic beliefs in early Islam  

Microsoft Academic Search

The aim of the present article is to analyse the assimilation of a series of ancient Semitic cosmogonic ideas by Islam via Judaism and Christianity, especially through the Aramaic-Arabic influence of the Syriac and Christian Arabic authors. The study focuses on a defective Hadith transmitted by the Andalus? traditionalist ?Abd al-Malik ibn ?ab?b (d. 852), which presents an old cosmogonic

Juan Pedro Monferrer-Sala

2011-01-01

225

Blausäuregas als bekämpfendes Holzschutzmittel für Kunstobjekte  

Microsoft Academic Search

Zusammenfassung  Durch Zyklon B hervorgerufene Schden an Tnungen und Malereien in der Pfarrkirche Untergriesbach bei Passau, die einige Monate vor der\\u000a Begasung restauriert worden war, wurden untersucht. Als Folge hoher relativer Luftfeuchtigkeit, bedingt durch heftigen Regen,\\u000a der whrend der Begasung einsetzte, bildete sich Schwitzwasser auf dem noch nicht karbonatisierten Kalkanstrich. In diesem\\u000a Wasser lste sich das Blausuregas, das unter Einflu des

D. Grosser; E. Roßmann

1974-01-01

226

Letters Regarding Article by Nasir et al, \\  

Microsoft Academic Search

We read with interest the article by Nasir et al1 that emphasizes the role of 12-lead ECG in the diagnosis of arrhythmogenic right ventricular cardiomyopathy\\/dysplasia (ARVC\\/D). The authors examined the ECG parameters in 50 affected patients, finding that almost all presented abnormal features and proposed as a new diagnostic ECG marker of ARVC a prolonged S-wave upstroke in V1 through

Willem Dewilde; Yves Vandekerckhove; Alexander Bol

227

The plastic deformation of TiAl  

Microsoft Academic Search

The deformation substructure of TiAl (Llo type ordered lattice) tested in compression, and the factors determining it were\\u000a investigated. Two types of dislocations take part in the plas-tic deformation, namely a\\/2 [110] and a\\/2 [Oil]. The latter\\u000a type will disorder the Llo super-lattice and therefore would be expected to move in pairs as superdislocations. Some obser-vations\\u000a are essentially in agreement

D. Shechtman; M. J. Blackburn; H. A. Lipsitt

1974-01-01

228

United States Patent [19] Burt et al.  

E-print Network

United States Patent [19] Burt et al. [11] Patent Number: 4 , 6 98, 84 3 [45] Date of Patent: Oct, 43, 49, 50, 54, 55 [56] References Cited U.S. PATENT DOCUMENTS 3,737,855 6/1973 Cutaia.S. Patent Oct. 6, 1987 Sheet 1 of 3 4,698,843 #12;U.S. Patent Oct. 6, 1987 Sheet 2 of 3 4,698,843 #12;U

Adelson, Edward

229

AlGaAs semiconductor laser illuminator  

Microsoft Academic Search

This program was directed at development of an acoustically covert, non-cryogenically cooled AlGaAs Semiconductor Laser Illuminator compatible with night vision equipment. The arraying approach undertaken for development used micro-cylindrical lenses attached to the face of the laser diodes and imaging the 2.5 micron junction. A conventionally drawn glass fiber was used for this lens. A solid glass integrator with a

W. W. Barratt; E. C. Lea; L. S. Ohara

1974-01-01

230

Euklid als Physiker: Die Realgeltung der Geometrie  

NASA Astrophysics Data System (ADS)

Es lässt sich beweisen, dass die Winkelsumme in einem ebenen, euklidischen Dreieck 180 Grad beträgt. Ebenso ergibt sich, dass die Winkelsumme in einem Dreieck auf einer Kugeloberfläche größer als 180 Grad ist. Auch der Satz des Pythagoras ist beweisbar. In allen Fällen beruhen die Beweise auf Euklids Parallelenaxiom. Das aber lässt sich nicht beweisen. Beweisbar aber ist, dass es in nicht-euklidischen Geomerien nicht gilt.

Genz, Henning

231

Role of Si on the Al behavior in the reaction layer of Al/UMo diffusion couples  

SciTech Connect

The basic experimental features characterizing the Al-Si/U-Mo interface are identified in this atomistic modeling effort, such as the formation of interfacial compounds, Si depletion in the Al matrix near the interface, reduced Al diffusion in the UMo solid solution, and the interaction between Mo and Si which inhibits Al and Si diffusion to the UMo bulk.

Garces, Jorge E.; Bozzolo, Guillermo; Hofman, Gerard; Rest, Jeffrey [Centro Atomico Bariloche, Comision Nacional de Energia Atomica, 8400 Bariloche (Argentina); Ohio Aerospace Institute, Cleveland, Ohio 44142 and NASA Glenn Research Center, Cleveland, Ohio 44135 (United States); Argonne National Laboratory, 9700 South Cass Ave., Argonne, Illinois 60439 (United States)

2007-02-12

232

A secondary analyses of Bradac et al.'s prototype process-monitoring experiment  

Microsoft Academic Search

We report on the secondary analyses of some conjectures and empirical evidence presented in Bradac et al.'s prototype process-monitoring experiment, published previously in IEEE Transactions on Software Engineering . We identify 13 conjectures in the original paper, and re-analyse six of these conjectures using the original evidence. Rather than rejecting any of the original conjectures, we identify assumptions underlying those

Austen Rainer

233

Mechanical properties of an Al\\/Mg\\/Al trilaminated composite fabricated by hot rolling  

Microsoft Academic Search

An Al\\/Mg\\/Al composite with a trilaminate structure was fabricated by hot rolling and its mechanical properties at quasi-static\\u000a rates of strain were investigated. The bonding strength of the trilaminated composite is about 40 MPa, mainly attributing\\u000a to the mechanical bond at the interfaces. The first layer failure strength of the laminated composite increases from 305 to\\u000a 372 MPa when the relative thickness

X. P. ZhangT; T. H. Yang; J. Q. Liu; X. F. Luo; J. T. Wang

2010-01-01

234

An overview of monolithic titanium aluminides based on Ti 3Al and TiAl  

Microsoft Academic Search

Titanium aluminides based on TiAl and Ti3Al are emerging as a revolutionary high temperature material. In order to confer these materials the thermomechanical properties required for industrial applications, two-phase alloys are developed by microalloying. That leads to formulate different alloy compositions adapted to the fabrication process and to the specific properties required for engineering applications. Knowledge of the fundamental understanding

S Djanarthany; J.-C Viala; J Bouix

2001-01-01

235

The influence of second phase Ti3Al on the deformation mechanisms in TiAl  

Microsoft Academic Search

Dislocations in samples of a heat-treated and quenched two phase Ti-46at.% Al alloy have been characterized, and those with Burgers vectors, b, given by b=½<1l0] and b=½<112] have been observed. The microstructure of deformed samples is characterized mainly by dislocations with b=½<1l0]. These dislocations have high Peierls stresses in TiAl of nominal purity, because of the directionality of bonds between

V. K. Vasudevan; M. A. Stucke; S. A. Court; H. L. Fraser

1989-01-01

236

Defect Band Characteristics in Mg-Al and Al-Si High-Pressure Die Castings  

Microsoft Academic Search

Bands of positive macrosegregation and porosity commonly follow the surface contour of components produced by high-pressure\\u000a die casting (HPDC). In this article, Al alloy AlSi7Mg and Mg alloys AZ91 and AM60 were cast into tensile test bars using cold-chamber\\u000a (cc) HPDC. Microstructural characterization revealed that externally solidified crystals (ESCs) are not necessary for defect\\u000a band formation, and that defect bands

C. M. Gourlay; H. I. Laukli; A. K. Dahle

2007-01-01

237

Tunneling properties of barriers in Nb\\/Al\\/AlOx\\/Nb junctions  

Microsoft Academic Search

We have measured DC I-V curves of niobium-trilayer (Nb\\/Al\\/AlOx\\/Nb) junctions with barriers thermally grown within a broad range of oxygen exposure E=Pt, from 2×105 to 2×109 Pa-s, and for applied electric fields ranging from zero all the way up to the breakdown - typically, above 10 MV\\/cm. The data can be reasonably well fitted by the direct theory assuming trapezoidal

S. K. Tolpygo; E. Cimpoiasu; X. Liu; N. Simonian; Yu. A. Polyakov; J. E. Lukens; K. K. Likharev

2003-01-01

238

Energetic ion bombarded Fe/Al multilayers  

SciTech Connect

The utility of ion-assisted deposition is investigated to explore the possibility of counteracting the deficiency of back-reflected current of Ar neutrals in the case of lighter elements such as Al. A range of energetically ion bombarded Fe/Al multilayers sputtered with applied surface bias of 0, -200, or -400 V were deposited onto Si(111) substrates in an argon atmosphere of 4 mTorr using a computer controlled dc magnetron sputtering system. Grazing incidence reflectivity and rocking curve scans by synchrotron x rays of wavelength of 1.38 A were used to investigate the structures of the interfaces produced. Substantial evidence has been gathered to suggest the gradual suppression of interfacial mixing and reduction in interfacial roughness with increases of applied bias. The densification of the Al microstructure was noticeable and may be a consequence of resputtering attributable to the induced ion bombardment. The average interfacial roughnesses were calculated for the 0, -200, and -400 V samples to be 7{+-}0.5, 6{+-}0.5, and 5{+-}0.5 A respectfully demonstrating a 30% improvement in interface quality. Data from rocking curve scans point to improved long-range correlated roughness in energetically deposited samples. The computational code based on the recursive algorithm developed by Parratt [Phys. Rev. 95, 359 (1954)] was successful in the simulation of the specular reflectivity curves.

Al-Busaidy, M.S.; Crapper, M.D. [College Science, Physics Department, Sultan Qaboos University, P.O. Box 36, Al-Khod 123 (Oman); Department of Physics, Loughborough University, Loughborough (United Kingdom)

2006-05-15

239

Liquid metal corrosion of 316L, Fe 3 Al, and FeCrSi in molten Zn-Al baths  

Microsoft Academic Search

Corrosion tests of 316L and two intermetallic compounds Fe3Al and FeCrSi in industrial Galvanizing (Zn-0.18Al), GALFAN (Zn-5Al), GALVALUME (Zn-55Al), and Aluminizing (Al-8Si) baths\\u000a and lab-scale static baths were conducted. In on-line tests in industrial hot-dip baths, 316L steel shows better corrosion\\u000a resistance than Fe3Al in Galvanizing, GALFAN, and GALVALUME baths. The corrosion resistance of 316L and Fe3Al is similar in

Xingbo Liu; Ever Barbero; Jing Xu; Matthew Burris; Keh-Minn Chang; Vinod Sikka

2005-01-01

240

Internal photoemission in Ag-Al2O3-Al junctions  

NASA Technical Reports Server (NTRS)

The magnitude of the photon-induced current in Ag-Al2O3-Al metal-oxide-metal junctions has been studied as a function of photon energy and angle of incident radiation. Photocurrents were theoretically analyzed on the basis of a modified vacuum photoemission model (Jain, 1975; Slayman et al., to be published). Optical constants previously reported in the literature (Irani et al., 1971; Ehnrereich et al., 1963) were used to calculate the true spatial generation rate in Ag and Al as a function of the angle, polarization of incident radiation, and film thickness. Results were found to be in very good agreement with experimentally determined values for a tunable dye laser with a KDP doubling crystal pumped by a Q-switched Nd:YAG laser with a LiIO3 doubling crystal. The system provided risetimes of 50 ns or less and peak powers of 10 W. Under short circuit conditions, the photoresponse to incident power was linear up to available power densities of 10 kW/sq cm. Quantum efficiencies of about 0.1% at zero-bias, near 3.8 eV under P polarization, were typically observed.

Guedes, J. M. P.; Slayman, C. W.; Gustafson, T. K.; Jain, R. K.

1979-01-01

241

The protective coatings of NdFeB magnets by Al and Al(Fe)  

SciTech Connect

NdFeB permanent magnets are coated by two different methods, dip coating and evaporation coating, with Al. It is found that an intermetallic reaction has occurred and formed a dominant phase of FeAl{sub 2.5}B{sub {ital x}} at the interface between the Al coating and the magnet material. Such reaction enhances strong bonding between the coating and the magnet. When Al(Fe) is used for the coating, no detectable intermetallic phase is observed, and therefore the amount of magnet material is conserved. We have studied the effect of the intermetallic phase on corrosion protection of the magnet. It is found that this phase is less resistive towards HNO{sub 3} solution than pure Al; but it is more resistive towards NaOH and NaCl. The investigation of the changes of microstructures of the coatings under different tempering conditions have also been carried out. The results show that the heat treatment at 500{degree}C for 10 min for a {approximately} 2 {mu}m thick Al coating by evaporation can produce an optimal layer of intermetallics. If the temperature is too low, the coating will not adhere to the magnet or if too high, it will fully react with the magnet and produce a rough coating surface. {copyright} {ital 1996 American Institute of Physics.}

Qin, C.; Li, A.S.; Ng, D.H. [Department of Physics, The Chinese University of Hong Kong, Shatin (Hong Kong)] [Department of Physics, The Chinese University of Hong Kong, Shatin (Hong Kong)

1996-04-01

242

Air Blast Characteristics for Laminate Al and Al-Ni Composites  

NASA Astrophysics Data System (ADS)

Air blast characteristics of laminate Al and Al-Ni composites were investigated in a 23 m^3 closed chamber. 50 to 100 ?m thick Al-Ni or Al foils were rolled to form a cylindrical shell, which was then compacted to a density larger than 99% TMD through an explosive formation technique. Charges were prepared using 2 kg C4 explosive packed in the laminate metal shell to a metal-explosive mass ratio of 1.75. Pressure and temperature were measured through transducers on the chamber wall and pyrometry sensors facing the charge center. The pressure history showed a double-shock front structure with an accelerating precursor shock of high amplitude followed by the primary blast, suggesting considerable early-time reaction of small laminate fragments. Significant enhanced explosion pressure (QSP) was observed as compared with baseline charges in solid shell. Recovered residue showed fragments in flakes with a considerable fraction in the molten. The pressure and temperature results are further analyzed to distinguish the reaction properties between the Al-Ni (gasless reaction for them alone) and Al laminates as well as their effect on air blast. The results are also compared with previous investigations using various shell materials and compositing techniques.

Zhang, Fan

2011-06-01

243

Redistribution of Ti and Al in deuterium charged TiAl  

NASA Technical Reports Server (NTRS)

The redistribution of titanium and aluminum in a single-phase TiAl alloy that has been exposed to a high pressure of deuterium gas at high temperature is studied. The microstructure in the as-received, uncharged condition consisted of single-phase gamma TiAl grains and a random distribution of precipitates. Precipitates were distributed throughout the matrix and along the grain boundaries. The chemistry of the precipitates varied considerably; some were rich in Al, while other were mostly Ti with some Si and Al. The dislocation density in most grains was low, although in a few grains a high dislocation density was observed. FCC deuterides with a lattice parameter of 0.45 nm form in a Ti-52.1Al-2.1Ta (at. pct) alloy after exposure to 1.38 MPa of deuterium gas at 650 C for 213 hr. The structure and lattice parameter are consistent with the formation of Ti(l)D2. The deuterides that form in this alloy are enriched in Ti and deficient in Al and Ta compared to the deuteride-free matrix. Regions of the matrix contiguous with the deuterides have a correspondingly enhanced aluminum and tantalum concentration.

Legzdina, D.; Robertson, I. M.; Birnbaum, H. K.

1992-01-01

244

Room Temperature Radiolytic Synthesized Cu@CuAlO(2)-Al(2)O(3) Nanoparticles.  

PubMed

Colloidal Cu@CuAlO(2)-Al(2)O(3) bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP) and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a (60)Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO(2)-Al(2)O(3) nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) showed that Cu@CuAlO(2)-Al(2)O(3) nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation. PMID:23109893

Abedini, Alam; Saion, Elias; Larki, Farhad; Zakaria, Azmi; Noroozi, Monir; Soltani, Nayereh

2012-01-01

245

FeAl and NbAl3 Intermetallic-HVOF Coatings: Structure and Properties  

NASA Astrophysics Data System (ADS)

Transition metal aluminides in their coating form are currently being explored in terms of resistance to oxidation and mechanical behavior. This interest in transition metal aluminides is mainly due to the fact that their high Al content makes them attractive for high-temperature applications. This is also a reason to study their resistance to wear; they may be suitable for use in applications that produce a lot of wear in aggressive environments, thus replacing established coating materials. In this study, the microstructure, microhardness, and wear and oxidation performance of FeAl and NbAl3 coatings produced by high-velocity oxy-fuel spraying are evaluated with two main aims: (i) to compare these two coating systems—a commonly studied aluminide (FeAl) and, NbAl3, an aluminide whose deposition by thermal spraying has not been attempted to date—and (ii) to analyze the relationship between their microstructure, composition and properties, and so clarify their wear and oxidation mechanisms. In the present study, the higher hardness of niobium aluminide coatings did not correlate with a higher wear resistance and, finally, although pesting phenomena (disintegration in oxidizing environments) were already known of in bulk niobium aluminides, here their behavior in the coating form is examined. It was shown that such accelerated oxidation was inevitable with respect to the better resistance of FeAl, but further improvements are foreseen by addition of alloying elements in that alloy.

Guilemany, J. M.; Cinca, N.; Dosta, S.; Cano, I. G.

2009-12-01

246

Study on the hydrolysis/precipitation behavior of Keggin Al13 and Al30 polymers in polyaluminum solutions.  

PubMed

The hydrolysis/precipitation behaviors of Al(3+), Al(13) and Al(30) under conditions typical for flocculation in water treatment were investigated by studying the particulates' size development, charge characteristics, chemical species and speciation transformation of coagulant hydrolysis precipitates. The optimal pH conditions for hydrolysis precipitates formation for AlCl(3), PAC(Al13) and PAC(Al30) were 6.5-7.5, 8.5-9.5, and 7.5-9.5, respectively. The precipitates' formation rate increased with the increase in dosage, and the relative rates were AlCl(3)>PAC(Al30)>PAC(Al13). The precipitates' size increased when the dosage increased from 50 microM to 200 microM, but it decreased when the dosage increased to 800 microM. The Zeta potential of coagulant hydrolysis precipitates decreased with the increase in pH for the three coagulants. The iso-electric points of the freshly formed precipitates for AlCl(3), PAC(Al13) and PAC(Al30) were 7.3, 9.6 and 9.2, respectively. The Zeta potentials of AlCl(3) hydrolysis precipitates were lower than those of PAC(Al13) and PAC(Al30) when pH>5.0. The Zeta potential of PAC(Al30) hydrolysis precipitates was higher than that of PAC(Al13) at the acidic side, but lower at the alkaline side. The dosage had no obvious effect on the Zeta potential of hydrolysis precipitates under fixed pH conditions. The increase in Zeta potential with the increase in dosage under uncontrolled pH conditions was due to the pH depression caused by coagulant addition. Al-Ferron research indicated that the hydrolysis precipitates of AlCl(3) were composed of amorphous Al(OH)(3) precipitates, but those of PAC(Al13) and PAC(Al30) were composed of aggregates of Al(13) and Al(30), respectively. Al(3+) was the most un-stable species in coagulants, and its hydrolysis was remarkably influenced by solution pH. Al(13) and Al(30) species were very stable, and solution pH and aging had little effect on the chemical species of their hydrolysis products. The research method involving coagulant hydrolysis precipitates based on Al-Ferron reaction kinetics was studied in detail. The Al species classification based on complex reaction kinetic of hydrolysis precipitates and Ferron reagent was different from that measured in a conventional coagulant assay using the Al-Ferron method. The chemical composition of Al(a), Al(b) and Al(c) depended on coagulant and solution pH. The Al(b) measured in the current case was different from Keggin Al(13), and the high Al(b) content in the AlCl(3) hydrolysis precipitates could not used as testimony that most of the Al(3+) was converted to highly charged Al(13) species during AlCl(3) coagulation. PMID:19409689

Chen, Zhaoyang; Luan, Zhaokun; Jia, Zhiping; Li, Xiaosen

2009-06-01

247

Ohmic contact to n-AlGaN through bonding state transition at TiAl interface  

NASA Astrophysics Data System (ADS)

We report the optimized ohmic contact to high Al content n-AlGaN through modification of the interfacial bonding state of TiAl alloy. First-principles calculations demonstrate that the change of interfacial bonding state (N rich to Al rich) at the TiAl/n-AlGaN interface is crucial for the formation of low barrier contact. The significant electron-transfer and strong orbital hybridization between the Ti atoms and the nearest Al atoms plays a key role in lowering the contact barrier. After treatment of the TiAl/n-AlGaN sample via rapid thermal annealing, perfectly linear I-V characteristic is achieved and the elemental profile by Auger electron spectroscopy confirms the N-rich-to-Al-rich local state transition in the interfacial layers.

Zhang, Binbin; Lin, Wei; Li, Shuping; Zheng, Yu; Yang, Xu; Cai, Duanjun; Kang, Junyong

2012-06-01

248

(5.5) BRAZING OF METALLIC-INTERMETALLIC LAMINATE (MIL) Ti-6Al-4V/Al3Ti COMPOSITES  

E-print Network

low density and high stiffness of Ti/Al3Ti based MIL composites compared to conventional monolithic) reported that electron beam welding of TiAl is possible, but that welding cracks cannot be avoided.86 TiAl3 20 Ti 0.20 Ti-6Al-4V and 0.80 TiAl3 In order to braze titanium materials, brazing fillers based

Meyers, Marc A.

249

High-efficiency AlGaN-based UV light-emitting diode on laterally overgrown AlN  

Microsoft Academic Search

Ultraviolet light-emitting diodes (UV-LEDs) with a peak wavelength of 335nm were fabricated on AlN\\/sapphire templates. As templates for the fabrication of UV-LEDs, planar AlN and epitaxial laterally overgrown (ELO) AlN on sapphire (0001) substrates were compared. The output power of UV-LEDs grown on ELO-AlN was 27 times higher than that of UV-LEDs on the planar AlN template.

Kentaro Nagamatsu; Narihito Okada; Hiroki Sugimura; Hirotoshi Tsuzuki; Fumiaki Mori; Kazuyoshi Iida; Akira Bando; Motoaki Iwaya; Satoshi Kamiyama; Hiroshi Amano; Isamu Akasaki

2008-01-01

250

Fabrication of high wear resistant Al\\/Al 3Ti metal matrix composite by in situ hot press method  

Microsoft Academic Search

In this study, hot press method has been used to fabricate Al\\/Al3Ti composite. In situ reacted Al3Ti compound is formed through Al and TiO2 powder blend in order to enhance mechanical properties and mainly wear resistance. After homogeneous blending of Al and TiO2, hot pressing was performed at 580°C at different durations and pressures. Scanning electron microscopy was used for

M. Nofar; H. R. Madaah Hosseini; N. Kolagar-Daroonkolaie

2009-01-01

251

Solidification Behavior of gamma'-Ni3Al Containing Alloys in the Ni-Al-O System  

NASA Technical Reports Server (NTRS)

The chemical activities of Al and Ni in gamma(prime)-Ni3Al-containing systems were measured using the multi-cell Knudsen effusion-cell mass spectrometry technique (multi-cell KEMS), over the composition range 8 - 32 at.%Al and temperature range T = 1400 - 1750 K. From these measurements a better understanding of the equilibrium solidification behaviour of gamma(prime)-Ni3Al-containing alloys in the Ni-Al-O system was established. Specifically, these measurements revealed that (1) gamma(prime)-Ni3Al forms via the peritectiod reaction, gamma + Beta (+ A12O3) = gamma (prime) (+ Al2O3), at 1633 +/- 1 K, (2) the {gamma + Beta + Al2O3} phase field is stable over the temperature range 1633 through 1640 K, and (3) equilibrium solidification occurs by the eutectic reaction, L (+ Al2O3) = gamma + Beta (+ Al2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%Al (at an unknown oxygen content). When projected onto the Ni-Al binary, this behaviour is inconsistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(prime)-Ni3Al phase field.

Copland, Evan

2007-01-01

252

Creep and Toughness of Cryomilled NiAl Containing Cr  

NASA Technical Reports Server (NTRS)

NiAl-AlN + Cr composites were produced by blending cryomilled NiAl powder with approx. 10 vol % Cr flakes. In comparison to the as-consolidated matrices, hot isostatically pressed Cr-modified materials did not demonstrate any significant improvement in toughness. Hot extruded NiAl-AlN+10.5Cr, however, possessed a toughness twice that determine for the base NiAl-AlN alloy. Measurement of the 1200 to 1400 K plastic flow properties revealed that the strength of the composites was completely controlled by the properties of the NiAl-AlN matrices. This behavior could be successfully modeled by the Rule-of-Mixtures, where load is shed from the weak Cr to the strong matrix.

Whittenberger, J. Daniel; Aikin, Beverly; Salem, Jon

2000-01-01

253

Computational study of OCN- chemisorption over AlN nanostructures  

NASA Astrophysics Data System (ADS)

Density functional theory (DFT) calculations were applied to consider the adsorption of cyanato anion (OCN-) on the external surfaces of AlN nanotubes and AlN nano-cages. The interaction energies of OCN- (N-side) interacted with (6, 0) and (4, 4) AlN nanotubes are about -2.84 and -2.72 eV, respectively, implying that the pristine (6, 0) AlN nanotubes is more reactive and sensitive than (4, 4) AlN nanotubes for OCN- detection. The adsorption energy of the reaction between OCN- and Al16N16 is too strong (-3.32 eV) than that of Al12N12 (-3.24 eV). The results demonstrate that the AlN nano-cages have a better condition for practical applications as a chemical adsorbent for the adsorption of OCN- compared with AlN nanotubes.

Baei, Mohammad T.; Taghartapeh, Mohammad Ramezani; Lemeski, E. Tazikeh; Soltani, Alireza

2014-08-01

254

Gaussian density-functional study for small neutral (Al n ), positive (Al{/n +}) and negative (Al{/n -}) aluminium clusters ( n=2 5)  

NASA Astrophysics Data System (ADS)

The structures and properties of Al n , Al{/n +}, Al{/n -} ( n=1,5) clusters have been investigated by using the Linear Combination of Gaussian Type Orbitals (LCGTO) method, considering Local (LSD) and Non Local (NLSD) Spin Density Approximations and employing a Model Core Potential (MCP) that allows the explicit treatment of 3 s 2 3 p 1 valence electrons. For each system different geometrical structures and electronic states have been considered. For Al3, Al{3/+}, Al{3/-} the most stable geometry proved to be the equilateral triangle ( D 3 h ). Al4 and Al{4/+} prefer the rhombus ( D 2 h ) structure, while the corresponding anion prefers the square ( D 4 h ) one. The trapezoidal form ( C 2 v ) is the most stable isomer for Al5, Al{5/+} and Al{5/-} clusters. The analysis of vibrational frequencies shows that these structures are minima in the potential energy surface. The binding energies ( D e), the adiabatic ionization potentials (IP) and electron affinities (EA), the chemical potentials or absolute hardnesses (?) and electronegativities (?) have been computed. Results are in good agreement with the available experimental data and the previous high level theoretical computations.

Calaminici, Patrizia; Russo, Nino; Toscano, Marirosa

1995-12-01

255

Alignment of the TiAl/Ti{sub 3}Al lamellar microstructure in TiAl alloys by growth from a seed material  

SciTech Connect

By using an appropriately oriented seed from the TiAl-Si system, the TiAl/Ti{sub 3}Al lamellar microstructure was aligned parallel to the growth direction in a number of directionally solidified TiAl-based alloys. The seed composition was kept constant at Ti-43Al-3Si (at.%) and the composition of the master ingots was varied for alloys in the TiAl-Si, TiAl-Nb-Si, and Ti-Al systems. The lamellar microstructure could be aligned for alloys containing up to approximately 47 at.% (Al + Si) in each of these systems. For the composition of seed material, Ti-43Al-3Si, where alpha is the primary solidification phase, the original orientation of the lamellar microstructure was maintained after heating to and cooling from the single-phase alpha region making seeding of the alpha phase possible. When this silicon containing seed was used, the nucleation of the primary beta phase in master alloys of Ti-(47 {minus} x)Al-xSi(x = 0 to 1 at.%) could be suppressed resulting in the nucleation and growth of only the alpha phase with an orientation determined by the seed crystal. After steady state conditions were reached, single PST crystals with an aligned lamellar microstructure could be grown at growth rates as high as 40 mm/h.

Johnson, D.R.; Masuda, Y.; Inui, H.; Yamaguchi, M. [Kyoto Univ. (Japan). Dept. of Materials Science and Engineering] [Kyoto Univ. (Japan). Dept. of Materials Science and Engineering

1997-06-01

256

Al-Ca and Al-Fe metal-metal composite strength, conductivity, and microstructure relationships  

SciTech Connect

Deformation processed metal-metal composites (DMMC’s) are composites formed by mechanical working (i.e., rolling, swaging, or wire drawing) of two-phase, ductile metal mixtures. Since both the matrix and reinforcing phase are ductile metals, the composites can be heavily deformed to reduce the thickness and spacing of the two phases. Recent studies have shown that heavily drawn DMMCs can achieve anomalously high strength and outstanding combinations of strength and conductivity. In this study, Al-Fe wire composite with 0.07, 0.1, and 0.2 volume fractions of Fe filaments and Al-Ca wire composite with 0.03, 0.06, and 0.09 volume fractions of Ca filaments were produced in situ, and their mechanical properties were measured as a function of deformation true strain. The Al-Fe composites displayed limited deformation of the Fe phase even at high true strains, resulting in little strengthening effect in those composites. Al-9vol%Ca wire was deformed to a deformation true strain of 13.76. The resulting Ca second-phase filaments were deformed to thicknesses on the order of one micrometer. The ultimate tensile strength increased exponentially with increasing deformation true strain, reaching a value of 197 MPa at a true strain of 13.76. This value is 2.5 times higher than the value predicted by the rule of mixtures. A quantitative relationship between UTS and deformation true strain was determined. X-ray diffraction data on transformation of Al + Ca microstructures to Al + various Al-Ca intermetallic compounds were obtained at the Advanced Photon Source at Argonne National Laboratory. Electrical conductivity was measured over a range of true strains and post-deformation heat treatment schedules.

Kim, Hyong June

2011-12-01

257

Electronic properties of AlGaAs and AlGaAs/GaAs heterostructures  

SciTech Connect

The electronic properties of free-standing Al/sub x/Ga/sub 1-x/As epitaxial layers and Al/sub x/Ga/sub 1-x/AsGaAs heterostructures are investigated. The fact that the persistent-photoconductivity (PPC) effect is a property Al/sub x/Ga/sub 1-x/As is established experimentally by observing the PPC effect in four free-standing Al/sub x/Ga/sub 1-x/As layers with alloy composition 0.26 less than or equal to x less than or equal to 0.32. The investigated samples were grown by LPE, MBE, and MOCVD. Experimental values of n/sub H/ and ..mu../sub H/ at room temperature for free-standing Al/sub x/Ga/sub 1-x/As layers are obtained. The author observed and investigated a new effect in Al/sub 0.3/Ga/sub 0.7/AsGaAs heterostructures that they called thermally stimulated persistent conductivity. After a heterostructure is cooled (53-55 min.) from room temperature to low temperatures (120 to 140K), the electron concentration and mobility do not stay constant with time. Electron concentration decreases slowly (days) while Hall mobility increases. This effect is attributed to the properties of the two-dimensional electron gas (2DEG) formed at the heterointerface. Investigation of the PPC effect in a heterostructure indicates that two mechanisms are responsible: at first, PPC due to the AlGaAs epitaxial layer is dominant, while at a later stage PPC due to the properties of the heterointerface dominates

Leybovich, I.S.

1986-01-01

258

Criterios de derivación en hiperplasia benigna de próstata para atención primaria  

Microsoft Academic Search

Benign prostatic hyperplasia (BPH) is a high prevalence condition in men over 50 years that requires continued assistance between primary care and urology. Therefore, consensus around common referral criteria was needed to guide and support both levels. Medical history, symptom assessment with International Prostate Symptom Score (IPSS) questionnaire, digital rectal examination and prostate-specific antigen (PSA) measurement are diagnostic tests available

F. J. Brenes Bermúdez; M. E. Naval Pulido; J. M. Molero García; D. Pérez Morales; J. Castiñeiras Fernández; J. M. Cozar Olmo; A. C. Fernández-Pro; J. A. Martín

2010-01-01

259

Intermediate temperature thermomechanical processing of Al 2090 for superplasticity  

NASA Technical Reports Server (NTRS)

The Al-Cu-Li phase diagram indicates that during thermomechanical processing of Al 2090 at 300 C both T(1) and T(2) phases will precipitate. Following work on Al-Mg-X alloys, it is possible that TMP at such temperatures might promote intragranular formation of these phases and promote microstructural refinement during recrystallization. Microstructural analyses reveal that the T(2) phase in Al 2090 may play a similar role to the beta-phase in Al-Mg-X alloys during microstructural evolution. Mechanical property data indicate that Al 2090 can be moderately (215-245 percent) superplastic at 370 C following processing at 300 C.

Hales, S. J.; Mcnelley, T. R.; Groh, G. E.

1989-01-01

260

ALS 2883: Analysis of spectroscopic features  

NASA Astrophysics Data System (ADS)

ALS 2883 (RA 13^{h} 02^{m} 47^{s}, DEC -63^{o} 50' 08'', M_{v} 10.1) is the first known radio pulsar with an emission B-type companion system, discovered in 1992. The Be companion of ALS 2883 has all line profiles in the visible range in emission. This emission is a common hallmark among many Be stars, and this effect is thought to be due to the presence of a circumstellar environment. Also, the star is orbiting a X-ray source as has been detected by the XMM-Newton Science Operation Center. In this study, we present the observations of ALS 2883 made at the OPD/LNA 1.60 m telescope with the Coudé spectrograph in the range 4000 to 5000 Å and S/N simeq 200, performed in April 2011. First-order estimations of T_{eff} and log g parameters have been performed through Johnson's UBV and JHK photometric calibrations. Projected rotation velocity V sin i has been estimated through the mean of the first zeroes of the Fourier transforms of neutral helium rotation profiles adopting linear, quadratic and square-root limb-darkening laws. The physical conditions of the circumstellar envelope were estimated through the solution of the radiative transport equation assuming local thermodynamic equilibrium within a disk-shaped circumstellar environment with a Keplerian velocity field. The radiative transport equation is solved assuming the Roche model as a boundary condition in the circumstellar environment. Iterating the computations with a downhill-simplex algorithm, this analysis leads to a best solution for an envelope with T simeq 9500 K, gas density ? simeq 2 × 10^{-15} g.cm^{-3}, internal radius r_{i} simeq 8 R_{odot} and external radius r_e simeq 30 R_{odot}, rotating with V_{rot} simeq 140 km.s^{-1} and expanding with V_{exp} simeq 90 km.s^{-1}.

Silva, A. R.; Levenhagen, R. S.; Künzel, R.; Leister, N. V.

2014-10-01

261

ICP etching of high Al mole fraction AlGaN  

NASA Astrophysics Data System (ADS)

The etching process has great influence on the performance of solar blind detector based on AlxGa1-xN epitaxial layers on sapphire substrate with high Al mole fraction grown by metal organic chemical vapor deposition (MOCVD) method. Traditional etching methods, including wet or reactive ion etching (RIE) are hard to achieve good result due to the high chemical-stability of AlGaN films with high Al mole fraction. In this paper, we studied on the inductively coupled plasma reactive ion etching (ICP-RIE) of high Al mole fraction AlxGa1-xN films (x>0.4) for fabricating high performance solar blind detectors. SiN was used as mask, and Cl2 and BCl3 were used as etching gas. Etching systems was selected from Oxford Inc. DC bias was controlled automatically. A 2.5:1 of selectivity on AlGaN and SiN was obtained with suitable flux and component of etching gas, RF power and ICP power. Etching velocity was adjusted mainly by RF power. The role of Ar, Cl2, and BCl3 in the etching process was also discussed.

Meng, Zhao; Yu, Libo; Li, Xiao; Liu, Qibin; Duan, Huiqiang; Yu, Chenhui; Chen, Changqing

2009-08-01

262

27Al-NQR/NMR Study of Kondo Semiconductor CeFe2Al10  

NASA Astrophysics Data System (ADS)

27Al-NQR/NMR measurements have been performed on CeFe2Al10 in relevance to the novel phase below T0=27 K of isostructural CeRu2Al10. NQR peaks are assigned to five crystallographically inequivalent Al sites. No splitting of the NQR spectra down to 1.5 K confirms the lack of phase transition in this compound. The gaplike decrease in the spin-lattice relaxation rate 1/T1 above about 20 K, following the Korringa law (T1T = const.) below 20 K, indicates a pseudogap opening near the Fermi level. The gap magnitude of 70 K with a mid-gap state of 42% is estimated based on a rectangular density of states. The gap magnitude is much larger than the gap of 15 K evaluated previously from the electrical resistivity, which suggests CeFe2Al10 to be a Kondo semiconductor with a Kondo temperature much higher than 300 K.

Kawamura, Yukihiro; Edamoto, Shingo; Takesaka, Tomoaki; Nishioka, Takashi; Kato, Harukazu; Matsumura, Masahiro; Tokunaga, Yo; Kambe, Shinsaku; Yasuoka, Hiroshi

2010-10-01

263

Photoionization electronic spectroscopy of AlAg  

SciTech Connect

AlAg is produced in a supersonic molecular beam by laser vaporization of alloy samples in a pulsed nozzle cluster source. Electronic spectroscopy is studied with resonant two-photon photoionization. In addition to the two electronic excited states previously reported by Clements and Barrow, we have observed ten new states. Vibrational analyses are presented for each of these states, and rotational analyses are given for selected states. The number and characteristics of these excited states are compared to the predictions of recent [ital ab] [ital initio] calculations.

Robbins, D.L.; Yeh, C.S.; Pilgrim, J.S.; Lang, G.L.; Duncan, M.A. (Department of Chemistry, University of Georgia, Athens, Georgia 30602 (United States))

1994-04-01

264

Development of SiAlON materials  

NASA Technical Reports Server (NTRS)

Cold pressing and sintering techniques were used to produce ceramic bodies in which the major phase was beta prime Si3-Al-O-N4 solid solution. A variety of foreign oxides were used to promote liquid phase sintering, and this resulted in the incorporation of additional solid phases in the ceramic bodies which controlled elevated temperature properties. None of the bodies studied to date exhibited both adequate high temperature mechanical properties and oxidation resistance. Criteria are suggested to guide the formulation of bodies with improved high temperature properties.

Layden, G. K.

1977-01-01

265

Radikale onkologische Chirurgie als Therapieprinzip beim Pankreaskarzinom  

Microsoft Academic Search

Zusammenfassung  \\u000a Grundlagen: Mit den heutigen tiefen Morbiditäts-und Mortalitätsraten für Pankreasresektionen ist die Indikationsstellung für eine Standard-\\u000a oder pyloruserhaltende Whipple-Operation weniger restriktiv zu stellen.\\u000a \\u000a \\u000a Methodik: Pankreasresektionen für Karzinome sollten deshalb in kurativer oder palliativer Absicht, wenn immer möglich, durchgeführt\\u000a werden. Verlangt werden dafür erfahrene Chirurgen mit über 10 Pankreaseingriffen pro Jahr und einer Mortalität von unter 10%.\\u000a Als Standard gilt eine

H. U. Baer; J. M. Läuffer; Ch Sadowski; M. W. Büchler

1997-01-01

266

Orbit stability of the ALS storage ring  

SciTech Connect

The Advanced Light Source (ALS) storage ring, a synchrotron light source of the third generation, is specified to maintain its electron orbit stable within one tenth of the rms beam size. In the absence of a dedicated orbit feed-back system, several orbit-distorting effects were investigated, aided by a new interactive simulation tool, the code TRACY V. The effort has led to a better understanding of the behavior of a variety of accelerator subsystems and in consequence produced a substantial improvement in day-to-day orbit stability.

Keller, R.; Nishimura, H.; Biocca, A. [and others

1997-05-01

267

Influence of Reaction with XeF2 on Surface Adhesion of Al and Al2O3 Surfaces  

SciTech Connect

The change of surface adhesion after fluorination of Al and Al{sub 2}O{sub 3} surfaces using XeF{sub 2} was investigated with atomic force microscopy. The chemical interaction between XeF{sub 2} and Al and Al{sub 2}O{sub 3} surfaces was studied by in situ x-ray photoelectron spectroscopy. Fresh Al and Al{sub 2}O{sub 3} surfaces were obtained by etching top silicon layers of Si/Al and Si/Al{sub 2}O{sub 3} with XeF{sub 2}. The surface adhesion and chemical composition were measured as a function of time after the exposure to air or annealing (at 200 C under vauum). The correlation between the adhesion force increase and presence of AlF{sub 3} on the surface was revealed.

Zhang, Tianfu; Park, Jeong Y.; Huang, Wenyu; Somorjai, Gabor A.

2008-07-28

268

Interfacial microstructure and growth mechanism of Al4C3 in Grf/Al composites fabricated by liquid pressure method.  

PubMed

In this study, Grf/Al composite was fabricated by liquid pressure method. The diffusion layer and the nucleation and growth of Al4C3 were observed at the interface of Grf/Al composites by TEM and HRTEM. The growth mechanism of Al4C3 was analyzed in detail by crystallography theory. It was found that Al4C3 had no phase relations with the carbon fiber. (0001) layer of Al4C3 was parallel with main growth direction. Both the diffusion layer at the interface and crystal structure of Al4C3 affected the shape of Al4C3. At a certain position, Al4C3 could connect two fibers when the fibers were close to each other. PMID:25041826

Xu, Wang; Chenchong, Wang; Zhichao, Zhang; Ping, Liang; Yanhua, Shi; Guofu, Zhang

2014-10-01

269

Influence of the Al source and synthesis of ordered Al-SBA-15 hexagonal particles with nanostairs and terraces.  

PubMed

We investigated the effect of various aluminum sources on the morphology and microstructure of nanoporous Al-SBA-15. With aluminum tri-sec-butoxide (Al-TSB), very large, ordered hexagonal rods of Al-SBA-15 covered by nanostairs and terraces were synthesized. Such a morphology was not obtained with an inorganic Al source (sodium aluminate) or with organic sources seemingly similar to Al-TSB, such as aluminum tri-tert-butoxide, aluminum tri-n-butoxide, or aluminum isopropoxide. The results obtained from X-ray diffraction, scanning electron microscopy/transmission electron microscopy, N(2) adsorption/desorption, and high-performance (129)Xe NMR suggest that preparing an organic Al-Si precursor by premixing liquid organic Al and Si sources (Al-TSB and tetraethyl orthosilicate) is crucial in obtaining highly ordered mesoporous Al-SBA-15 materials with a well-defined morphology. PMID:15723513

Li, Wenjiang; Huang, Shing-Jong; Liu, Shang-Bin; Coppens, Marc-Olivier

2005-03-01

270

Performance of LiAl/LiI(Al2O3)/FeS2 thermal batteries  

NASA Astrophysics Data System (ADS)

Performances of the LiAl/LiI(Al2O3)/FeS2 systems with different percentages of Al2O3 in the electrolyte were tested from 460 C to 580 C at various current densities and were compared with the performance of the LiAl/LiCl-KCl/FeS2 system. The results of single-cell and battery tests indicate that the LiAl/LiI(Al2O3)/FeS2 system has a feasibility for thermal potential applications. Compared to the LiAl/LiCl-KCl/FeS2 system, the LiI(Al2O3)-based system has poorer specific conductance and lower cell potential, but longer discharge life and greater capacity. A salient feature of the LiI(Al2O3)-based system, important for reliability considerations, is its apparent greater flexibility in battery internal heat control.

Lin, Yung-Hsin; Yu, Kuo-Tung; Yao, Pei-Chin; Hsu, Shu-En

271

Transplacental passage of 26Al from pregnant rats to fetuses and 26Al transfer through maternal milk to suckling rats  

NASA Astrophysics Data System (ADS)

Aluminium (Al) is toxic to the growth of fetuses and sucklings. However, the incorporation of Al into fetuses and sucklings in the periods of gestation and lactation has not been well clarified because Al lacks a suitable isotope for a tracer experiment. In this study, we used 26Al (a radioisotope of Al with half-life of 716,000 yr) as a tracer, and measured 26Al incorporation into fetuses and sucklings by accelerator mass spectrometry (AMS). To investigate Al incorporation into fetuses through transplacental passage, 26Al ( 26AlCl 3) was subcutaneously injected into pregnant rats on day 15 of gestation. 26Al was also subcutaneoulsy injected into lactating rats from day 1 to day 20 postpartum. By day 20 of gestation, 0.2% of the 26Al injected into a pregnant rat had been transferred to the fetuses, and 26Al was detected in the brain and liver of the fetuses. On day 9 postpartum, high levels of 26Al were demonstrated in the brain, liver, kidneys and blood of suckling rats. It is concluded that 26Al subcutaneously injected into pregnant rats and/or lactating rats is incorporated into their offspring through transplacental passage and/or maternal milk.

Yumoto, S.; Nagai, H.; Matsuzaki, H.; Kobayashi, T.; Tada, W.; Ohki, Y.; Kakimi, S.; Kobayashi, K.

2000-10-01

272

TEM characterization of Al/Al{sub 2}O{sub 3} composite fabricated by reactive metal infiltration  

SciTech Connect

The microstructure of Al/{alpha}-Al{sub 2}0{sub 3} composites made by infiltrating Al into dense mullite preforms has been characterized using transmission electron microscopy. Observations revealed that the formation of the Al/Al{sub 2}0{sub 3} composites involves three stages. Initially, Al infiltrates into a dense mullite preform through grain boundary diffusion, and reacts with mullite at grain boundaries to form a partial reaction zone. Then, a complete reaction takes place in the reaction region between the partial reaction zone and the full reaction zone to convert the dense mullite preform to a composite of {alpha}-Al{sub 2}0{sub 3} (matrix) and an Al-Si phase (thin channels). Finally, the reduced Si from the reaction diffuses out of the Al/Al{sub 2}0{sub 3} composite through the metal channels, whereas Al from the molten Al pool is continuously drawn to the reaction region until the mullite preform is consumed or the sample is removed from the molten Al pool. Based on the observed microstructure, infiltration mechanisms have been discussed, and a growth model of the composites is proposed in which the process involves repeated nucleation of Al{sub 2}0{sub 3} grains and grain growth.

Gao, Y.; Jia, J. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Materials Engineering; Loehman, R.E.; Ewsuk, K.G. [Sandia National Labs., Albuquerque, NM (United States)

1994-12-31

273

High-temperature deformation of uniaxially aligned lamellar TiAl/Ti{sub 3}Al  

SciTech Connect

Uniaxially aligned polysynthetically twinned two-phase TiAl/Ti{sub 3}Al material is produced by induction zone melting and deformed in uniaxial compression. Above 1,000 K the strain rate sensitivity is independent of the lamellar orientation and increases strongly with increasing deformation temperature. Results for the strain rate sensitivity parameters are somewhat lower than those obtained for {gamma}-TiAl single- and polycrystals. If the lamellae are oriented parallel or perpendicular to the deformation axis, the flow stress decreases with increasing strain. After plastic deformation the dislocation density in the lamellae is remarkably low indicating recovery processes. At the lamellar interfaces misfit dislocations and periodic arrangements of dislocations with Burgers vectors inclined to the lamellar boundaries are found. In contrast to deformation at lower temperatures, deformation twinning is rare.

Heinrich, H.; Abaecherli, V.; Wilkins, D.J.; Kostorz, G.

1999-07-01

274

Local stress-induced effects on AlGaAs/AlOx oxidation front shape  

NASA Astrophysics Data System (ADS)

The lateral oxidation of thick AlGaAs layers (>500 nm) is studied. An uncommon shape of the oxide tip is evidenced and attributed to the embedded stress distribution, inherent to the oxidation reaction. Experimental and numerical studies of the internal strain in oxidized AlxGa1-xAs/GaAs structures were carried out by dark-field electron holography and finite element methods. A mapping of the strain distribution around the AlGaAs/oxide interface demonstrates the main role of internal stress on the shaping of the oxide front. These results demonstrate the high relevance of strain in oxide-confined III-V devices, in particular, with over-500-nm thick AlOx confinement layers.

Chouchane, F.; Almuneau, G.; Cherkashin, N.; Arnoult, A.; Lacoste, G.; Fontaine, C.

2014-07-01

275

A Correlation Between Failure Angle and Constituent for Al-AlN Composites Under Uniaxial Tensile Conditions  

NASA Astrophysics Data System (ADS)

Al-AlN composites with different AlN reinforcement fractions and porosity were fabricated through nitridation of laser-sintered AA 6061 powder followed by infiltration with AA 6061. Their failure behaviors were investigated under uniaxial tensile loading conditions. Tensile testing and fractography indicate that the fracture mode changes gradually from ductile to brittle fracture with increasing AlN reinforcement or porosity. An analysis of the fractured Al-AlN tensile samples reveals that the failure surface angle, ?, is dictated by the volume fraction of the matrix, f m , in a form of tan ? = f {/m 5.5}.

Yu, Peng; Schaffer, G. B.; Qian, Ma

2012-09-01

276

Growth and characterization of TiAlN/CrAlN superlattices prepared by reactive direct current magnetron sputtering  

SciTech Connect

TiAlN and CrAlN coatings were prepared using a reactive direct current magnetron sputtering system from TiAl and CrAl targets. Structural characterization of the coatings using x-ray diffraction (XRD) revealed the B1 NaCl structure of TiAlN and CrAlN coatings with a prominent reflection along the (111) plane. The XPS data confirmed the bonding structures of TiAlN and CrAlN single layer coatings. Subsequently, nanolayered multilayer coatings of TiAlN/CrAlN were deposited on silicon and mild steel (MS) substrates at different modulation wavelengths ({lambda}) with a total thickness of approximately 1.0 {mu}m. The modulation wavelengths were calculated from the x-ray reflectivity data using modified Bragg's law. TiAlN/CrAlN multilayer coatings were textured along (111) for {lambda}<200 A and the XRD patterns showed the formation of superlattice structure for coatings deposited at {lambda}=102 A. The x-ray reflectivity data showed reflections of fifth and seventh orders for multilayer coatings deposited at {lambda}=102 and 138 A, respectively, indicating the formation of sharp interfaces between TiAlN and CrAlN layers. The cross-sectional scanning electron microscopy image of TiAlN/CrAlN multilayer coatings indicated a noncolumnar and dense microstructure. A maximum hardness of 39 GPa was observed for TiAlN/CrAlN multilayer coatings deposited at {lambda}=93 A, which was higher than the rule-of-mixture value (30 GPa) for TiAlN and CrAlN. Study of thermal stability of the coatings in air using micro-Raman spectroscopy indicated that the TiAlN/CrAlN multilayer coatings were stable up to 900 deg. C in air. TiAlN/CrAlN multilayer coatings also exhibited improved corrosion resistance when compared to the MS substrate.

Barshilia, Harish C.; Deepthi, B.; Rajam, K. S.; Bhatti, Kanwal Preet; Chaudhary, Sujeet [Surface Engineering Division, National Aerospace Laboratories, Post Bag No. 1779, Bangalore 560 017 (India); Department of Physics, Indian Institute of Technology, Delhi, New Delhi 110 016 (India)

2009-01-15

277

The embrittlement of Al-Zn-Mg and Al-Mg alloys by water vapor  

NASA Astrophysics Data System (ADS)

Al4.5Zn1.5Mg and Al5Mg were reacted in water-vapor saturated air (WVSA) at 120°C and tensile tested. After an initial loss of ductility with exposure time, probably caused by hydrogen embrittlement of the grain boundaries, between 15 hours and 25 hours exposure the mechanical properties of Al4.5Zn1.5Mg improved, this effect being due both to a reduced corrosion activity of the grain boundaries in producing embrittling hydrogen at the external surface and to grain boundary MgZn2 precipitates acting as hydrogen traps. After 25 hours exposure water was shown to penetrate the grain boundaries, and a layered corrosion product identified as the aluminum hydroxides boehmite and diaspore was formed. This resulted in a marked fall of ductility. Re-solution heat treatment and reaging partially recovered the mechanical properties of Al4.5Zn1.5Mg if the exposure time was less than 50 hours, and would not recover properties for longer exposure times. Small additions (0.1 pct) of iron and nickel to Al4.5Zn1.5Mg lessened the grain boundaries’ sensitivity to corrosive attack whereas the addition of 0.1 pct copper did not. Also, the former two additions did not cause the relative ductility increase during 15 to 25 hours exposure in WVSA at 120°C shown by Al4.5Zn1.5Mg. It is proposed that these elements alter the magnesium segregation levels at the grain boundaries which in turn affects their electrochemical attack.

Tuck, C. D. S.

1985-08-01

278

InAs/AlSb short wavelength quantum cascade lasers.  

E-print Network

??Application of InAs/AlSb materials system for development of short-wavelength quantum cascade lasers is explored. Molecular beam epitaxy (MBE) technology allowing to grow multiperiodical unstrained InAs/AlSb… (more)

Devenson, Jan

2010-01-01

279

75 FR 20773 - Establishment of Class E Airspace; Jackson, AL  

Federal Register 2010, 2011, 2012, 2013

...09-ASO-27] Establishment of Class E Airspace; Jackson, AL AGENCY: Federal Aviation Administration (FAA...December 7, 2009 that establishes Class E airspace at Jackson Muni, Jackson, AL. DATES: Effective Date: 0901 UTC, April...

2010-04-21

280

PIT INITIATION IN AlO{sub X}/Al THIN FILMS  

SciTech Connect

The electrochemical responses of AlO{sub x}/Al thin films have been investigated as a function of film growth conditions which produce films with different grain orientation, size and morphology. Films with smooth, 150 nm diameter, randomly oriented grains show a higher pitting potential and lower passive current than those films with large grain-boundary grooving from a mixture of smooth micron-sized, (200)-oriented grains and 300--500 nm diameter, (220)-oriented grains. These results suggest that surface roughness from grain-boundary grooving affects the pitting resistance more strongly than does the grain boundary density.

SON,K.A.; BARBOUR,J.C.; MISSERT,N.; WALL,F.D.; COPELAND,R.G.; MARTINEZ,M.A.; MINOR,K.G.; BUCHHEIT,R.G.; ISAACS,H.S.

1998-11-01

281

Microstructure and Creep Properties of TiAl-Ti3Al In-Situ Composites  

SciTech Connect

Objectives: {lg_bullet} Exploit thermomechanical-processing techniques to fabricate TiAl/Ti3Al in-situ laminate composites with the size of lamella width down to submicron or nanometer length-scales. {lg_bullet} Characterize microstructure and elevated-temperature creep resistance of the in-situ composites. {lg_bullet} Investigate the fundamental interrelationships among microstructures, alloying additions, and mechanical properties of the in-situ composites so as to achieve the desired properties of the in-situ composites for high-temperature structural applications.

Hodge, A M; Hsiung, L L

2004-02-18

282

InAlGaAs/AlGaAs Superlattices for Polarized Electron Photocathodes  

SciTech Connect

Highly efficient emitters of polarized electrons based on the InAlGaAs/AlGaAs superlattice give an optimistic prognosis to explorations of such structures as the sources for accelerators. A new set of these SL structures with minimized conduction band offset was designed and recently tested. A new technology of surface protection in MBE growth leads to a significantly reduced heat-cleaning temperature. At these lowered cleaning temperatures, the thermal degradation of the working structure parameters is avoided. As a result a polarization P of up to 91% at corresponding quantum efficiency (QE) of 0.3% was achieved at room temperature.

Mamaev, Yu.A.; Subashiev, A.V.; Yashin, Yu.P.; Gerchikov, L.G.; /St. Petersburg Polytechnic Inst.; Maruyama, T.; Luh, D.-A.; Clendenin, J.E.; /SLAC; Ustinov, V.M.; Zhukov,; /Ioffe Phys. Tech. Inst.

2005-08-15

283

Lasing characteristics of visible AlGaInP/AlGaAs vertical-cavity lasers  

SciTech Connect

We report the lasing characteristics of gain-guided AlGaInP/AlGaAs visible vertical-cavity surface-emitting laser diodes. At room temperature, continuous-wave operation is achieved over the wavelength range of 657--685 nm with the minimum threshold current at 670 nm. Devices with a 10-[mu]m diameter have threshold currents as low as 1.25 mA at room temperature (297 K) and 0.8 mA at 250 K. In addition, a single predetermined linear polarization state is found, independent of the lasing mode order and operating temperature.

Choquette, K.D.; Schneider, R.P. Jr.; Lott, J.A. (Sandia National Laboratories, Albuquerque, New Mexico 87185-5800 (United States))

1994-07-01

284

Lasing characteristics of visible AlGaInP/AlGaAs vertical-cavity lasers.  

PubMed

We report the lasing characteristics of gain-guided AlGaInP/AlGaAs visible vertical-cavity surface-emitting laser diodes. At room temperature, continuous-wave operation is achieved over the wavelength range of 657-685 nm with the minimum threshold current at 670 nm. Devices with a 10-microm diameter have threshold currents as low as 1.25 mA at room temperature (297 K) and 0.8 mA at 250 K. In addition, a single predetermined linear polarization state is found, independent of the lasing mode order and operating temperature. PMID:19844504

Choquette, K D; Schneider, R P; Lott, J A

1994-07-01

285

Fabrication and Characterization of Thin-Barrier AlGaN\\/AlN\\/GaN HEMTs  

Microsoft Academic Search

The growth, fabrication, and performance of Al0.5Ga0.5N\\/AlN\\/GaN high-electron-mobility transistors (HEMTs) with a total barrier thickness of 7 nm are reported. An optimized surface passivation and an ohmic recess etch yield HEMTs exhibiting 0.72 S\\/mm peak extrinsic dc transconductance at a current density of 0.47 A\\/mm. Devices with a gate length of 90 nm achieve 78 GHz unity-current-gain frequency and up

Jonathan G. Felbinger; Martin Fagerlind; Olle Axelsson; Niklas Rorsman; Xiang Gao; Shiping Guo; William J. Schaff; Lester F. Eastman

2011-01-01

286

Vanishing quasiparticle density in a hybrid Al/Cu/Al single-electron transistor  

NASA Astrophysics Data System (ADS)

The achievable fidelity of many nanoelectronic devices based on superconducting aluminum is limited by either the density of residual nonequilibrium quasiparticles nqp or the density of quasiparticle states in the gap, characterized by Dynes parameter ?. We infer upper bounds nqp<0.033?m-3 and ?<1.6×10-7 from transport measurements performed on Al/Cu/Al single-electron transistors, improving previous results by an order of magnitude. Owing to efficient microwave shielding and quasiparticle relaxation, a typical number of quasiparticles in the superconducting leads is zero.

Saira, O.-P.; Kemppinen, A.; Maisi, V. F.; Pekola, J. P.

2012-01-01

287

InAs\\/AlGaAs QDs for intersubband devices  

Microsoft Academic Search

InAs quantum dots were grown on AlxGa1?xAs surfaces with varying Al concentrations. Atomic force microscopy measurements conducted on surface quantum dots showed that surfaces with higher Al concentrations produce smaller dots compared to GaAs surfaces. Photoluminescence measurements performed on buried quantum dots showed a blue shift and spectral broadening of the luminescence signal for increasing Al concentrations. For Al concentrations

M. Schramboeck; A. M. Andrews; P. Klang; W. Schrenk; G. Hesser; F. Schäffler; G. Strasser

2008-01-01

288

Growth and Oxidation of Thin Film Al(2)Cu  

SciTech Connect

Al{sub 2}Cu thin films ({approx} 382 nm) are fabricated by melting and resolidifying Al/Cu bilayers in the presence of a {micro} 3 nm Al{sub 2}O{sub 3} passivating layer. X-ray Photoelectron Spectroscopy (XPS) measures a 1.0 eV shift of the Cu2p{sub 3/2} peak and a 1.6 eV shift of the valence band relative to metallic Cu upon Al{sub 2}Cu formation. Scanning Electron microscopy (SEM) and Electron Back-Scattered Diffraction (EBSD) show that the Al{sub 2}Cu film is composed of 30-70 {micro}m wide and 10-25 mm long cellular grains with (110) orientation. The atomic composition of the film as estimated by Energy Dispersive Spectroscopy (EDS) is 67 {+-} 2% Al and 33 {+-} 2% Cu. XPS scans of Al{sub 2}O{sub 3}/Al{sub 2}Cu taken before and after air exposure indicate that the upper Al{sub 2}Cu layers undergo further oxidation to Al{sub 2}O{sub 3} even in the presence of {approx} 5 nm Al{sub 2}O{sub 3}. The majority of Cu produced from oxidation is believed to migrate below the Al{sub 2}O{sub 3} layers, based upon the lack of evidence for metallic Cu in the XPS scans. In contrast to Al/Cu passivated with Al{sub 2}O{sub 3}, melting/resolidifying the Al/Cu bilayer without Al{sub 2}O{sub 3} results in phase-segregated dendritic film growth.

SON,KYUNG-AH; MISSERT,NANCY A.; BARBOUR,J. CHARLES; HREN,J.J.; COPELAND,ROBERT GUILD; MINOR,KENNETH G.

2000-01-18

289

Quantitative Aspects of 27Al MAS NMR of Calcium Aluminoferrites  

Microsoft Academic Search

27Al MAS NMR spectra of synthetic calcium aluminoferrites, Ca2AlxFe2?xO5 with x = 0.93, 1, 1.33, reveal only a few percent of the expected intensity for the 27Al central transition, indicating that the calcium aluminoferrite phase in Portland cements can barely be observed by 27Al MAS NMR. This result supports the use of 27Al MAS NMR for quantitative analysis of the

Jørgen Skibsted; Hans J. Jakobsen; Christopher Hall

1998-01-01

290

Application of cast gamma TiAl for automobiles  

Microsoft Academic Search

Studies of cast gamma TiAl applied for engine valves and turbocharger confirmed excellent performances. The durability of TiAl valves was also proven. Two cast gamma TiAl alloys were developed for the engine valves and the turbine wheels of turbochargers. New precision casting process of LEVICAST and induction brazing process of the gamma TiAl and alloy steels were proposed as advanced

T. Noda

1998-01-01

291

Development of Enhancement Mode AlN/GaN HEMTs  

SciTech Connect

Demonstration of enhancement mode AlN/GaN high electron mobility transistor (HEMT) using oxygen plasma treatment on the gate area prior to the gate metalliation deposition was achieved. Starting with a depletion mode AlN/GaN HEMT, the threshold voltage of the HEMT could be shifted from 3.2 to 1V depending on the oxygen plasma treatment time to convert the AlN into Al oxide. The gate current was also reduced when the threshold voltage

Chang, C. Y. [University of Florida; Pearton, S. J. [University of Florida; Lo, C. F. [University of Florida; Kravchenko, Ivan I [ORNL; Dabiran, A. M. [SVT Associates, Inc.; Wowchak, A. M. [SVT Associates, Inc.; Cui, B. [SVT Associates, Inc.; Chow, P. P. [SVT Associates, Inc.; Ren, F. [University of Florida

2009-01-01

292

Al-Fe-Ni (Aluminum-Iron-Nickel)  

SciTech Connect

[88Ray] reviewed the experimental results on the phase equilibria of this system. The reviewed results were presented as: (1) liquidus and solidus projections for Al-poor Fe-Ni alloys and for compositions near the Al-corner; (2) a reaction sequence for the solidification reactions; (3) isothermal sections at 1250, 950, 850, and 750{degrees}C for Al-poor Fe-Ni compositions; and (4) an isothermal section at 600{degrees}C near the Al-corner.

Raghavan, V.

1994-08-01

293

Mechanisms of elevated-temperature deformation in the B2 aluminides NiAl and CoAl  

NASA Technical Reports Server (NTRS)

A strain rate change technique, developed previously for distinguishing between pure-metal and alloy-type creep behavior, was used to study the elevated-temperature deformation behavior of the intermetallic compounds NiAl and CoAl. Tests on NiAl were conducted at temperatures between 1100 and 1300 K while tests on CoAl were performed at temperatures ranging from 1200 to 1400 K. NiAl exhibits pure-metal type behavior over the entire temperature range studied. CoAl, however, undergoes a transition from pure-metal to alloy-type deformation behavior as the temperature is decreased from 1400 to 1200 K. Slip appears to be inherently more difficult in CoAl than in NiAl, with lattice friction effects limiting the mobility of dislocations at a much higher tmeperature in CoAl than in NiAl. The superior strength of CoAl at elevated temperatures may, therefore, be related to a greater lattice friction strengthening effect in CoAl than in NiAl.

Yaney, D. L.; Nix, W. D.

1988-01-01

294

Mechanochemical Behavior of NiO-Al-Fe Powder Mixtures to Produce (Ni, Fe)3Al-Al2O3 Nanocomposite Powder  

NASA Astrophysics Data System (ADS)

(Ni, Fe)3Al-30 vol pct Al2O3 nanocomposite powder was synthesized by mechanochemical reaction of Fe-NiO-Al powder mixtures. Structural evolution during mechanical alloying was studied by employing X-ray diffractometry (XRD), differential thermal analysis (DTA), and transmission electron microscopy (TEM). After 78 minutes of milling, the (Ni, Fe)3Al-30 vol pct Al2O3 nanocomposite can be synthesized by reaction 3Fe + 7Al + 6NiO with a combustion mode. DTA results revealed that milling for 60 minutes decreases the temperature of reaction from 1040 K to 898 K (767 °C to 625 °C). TEM images corroborate a homogenous dispersion of reinforcements in the matrix of the nanocomposite proving that the reduction in the crystallite size of both reinforcements and matrix is within the nanometer range.

Adabavazeh, Z.; Karimzadeh, F.; Enayati, M. H.

2012-09-01

295

Effect of growth temperature of initial AlN buffer on the structural and optical properties of Al-rich AlGaN  

NASA Astrophysics Data System (ADS)

High Al-content Al xGa 1-xN epilayers with x=0.62-0.64 were grown on AlN buffer by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). As growth temperature of initial AlN buffer increased, the full-width at half-maximum (FWHM) of the AlGaN (0 0 2) rocking curves decreased from 942 to 637 arcsec. Meanwhile, vacuum ultraviolet (VUV) photoluminescence (PL) spectroscopy showed that band edge exciton transition was greatly intensified, while deep level radiative recombination especially peaked at 304 nm was effectively suppressed. They were ascribed to the reducing of threading dislocations (TDs) in the AlGaN epilayers.

Peng, M. Z.; Guo, L. W.; Zhang, J.; Yu, N. S.; Zhu, X. L.; Yan, J. F.; Wang, Y.; Jia, H. Q.; Chen, H.; Zhou, J. M.

2007-09-01

296

Mixing of Al into uranium silicides reactor fuels  

SciTech Connect

SEM observations have shown that irradiation induced interaction of the aluminum cladding with uranium silicide reactor fuels strongly affects both fission gas and fuel swelling behaviors during fuel burn-up. The authors have used ion beam mixing, by 1.5 MeV Kr, to study this phenomena. RBS and the {sup 27}Al(p, {gamma}) {sup 28}Si resonance nuclear reaction were used to measure radiation induced mixing of Al into U{sub 3}Si and U{sub 3}Si{sub 2} after irradiation at 300 C. Initially U mixes into the Al layer and Al mixes into the U{sub 3}Si. At a low dose, the Al layer is converted into UAl{sub 4} type compound while near the interface the phase U(Al{sub .93}Si{sub .07}){sub 3} grows. Under irradiation, Al diffuses out of the UAl{sub 4} surface layer, and the lower density ternary, which is stable under irradiation, is the final product. Al mixing into U{sub 3}Si{sub 2} is slower than in U{sub 3}Si, but after high dose irradiation the Al concentration extends much farther into the bulk. In both systems Al mixing and diffusion is controlled by phase formation and growth. The Al mixing rates into the two alloys are similar to that of Al into pure uranium where similar aluminide phases are formed.

Ding, F.R.; Birtcher, R.C.; Kestel, B.J.; Baldo, P.M. [Argonne National Lab., IL (United States). Materials Science Div.

1996-11-01

297

OVERVIEW NO. 136 DIFFUSION IN THE TiAl SYSTEM  

E-print Network

OVERVIEW NO. 136 DIFFUSION IN THE Ti±Al SYSTEM Y. MISHIN1 { and Chr. HERZIG2 1 DepartmentÐMany properties of industrial Ti±Al alloys, such as high-temperature stability of the lamellar structure and creep and design of industrial Ti±Al alloys. This paper gives an overview of recent progress in experimental

Mishin, Yuri

298

The Practical Enactment of Adventure Learning: Where Will You AL@?  

ERIC Educational Resources Information Center

The Adventure Learning (AL) approach to designing and implementing learning experiences has great potential for practitioners. This manuscript delineates the practical enactment of AL to support the K-12 community, teacher educators, and residential environmental science program providers in the conceptualization and delivery of their own AL…

Miller, Brant G.; Hougham, R. Justin; Eitel, Karla Bradley

2013-01-01

299

Supporting Information Koenderink et al. 10.1073/pnas.0903974106  

E-print Network

filaments or FLNa dimers per actin filament. Koenderink et al. www.pnas.org/cgi/content/short/0903974106 4 and passive actin­scruin network. Koenderink et al. www.pnas.org/cgi/content/short/0903974106 5 of 5 #12;Supporting Information Koenderink et al. 10.1073/pnas.0903974106 FLNa/actin filament myosin

Fraden, Seth

300

Igor Kuznecov MOVPE von AlGaN-Schichten mit  

E-print Network

moglich, die Emissionswellenlange einer LED von der Wellenlange des GaN (365nm) bis zur Wellenlange des Al Diplomarbeit ist das Wachstum von LED-Schichten mittels MOVPE. Dabei muss die Komposition des AlGaN und dieIgor Kuznecov MOVPE von AlGaN-Schichten mit hohem Aluminiumgehalt Es gibt zahlreiche

Nabben, Reinhard

301

Effect of Ar gas pressure on growth, structure, and mechanical properties of sputtered Ti, Al, TiAl, and Ti 3Al films  

Microsoft Academic Search

Single layers of Ti, Al, TiAl and Ti3Al were sputter deposited on to 2? oxidized Si ?111? wafers and 7059 Corning Glass to study the effect of film thickness, temperature, and sputtering gas pressure on the mechanical and physical properties. In the present investigation, sputtering gas pressure was varied from 2 mT to 10 mT. The film thickness was varied

M. Chinmulgund; R. B. Inturi; J. A. Barnard

1995-01-01

302

Spinelisation and properties of Al 2O 3–MgAl 2O 4–C refractory: Effect of MgO and Al 2O 3 reactants  

Microsoft Academic Search

The effect of particle size of MgO and Al2O3 on the spinel formation associated with permanent linear change on reheating (PLCR) and microstructure of Al2O3–MgAl2O4–C refractory is investigated as a function of heating cycle at 1600°C with 2h holding at each cycle. It was found that rate of spinel formation and associated volume expansion is very much dependent on the

H. S. Tripathi; A. Ghosh

2010-01-01

303

Al2C monolayer: the planar tetracoordinate carbon global minimum  

NASA Astrophysics Data System (ADS)

Inspired by our theoretical finding that C2Al62- has a planar D2h minimum with two planar tetracoordinate carbons (ptCs), we computationally designed a new two-dimensional (2D) inorganic material, an Al2C monolayer. All carbons in this monolayer are ptC's, stabilized inductively by binding to four electropositive Al atoms in the same plane. The Al2C monolayer is semiconducting with an indirect minimum band gap and a slightly larger direct band gap. Good persistence of the Al2C monolayer is indicated by its moderate cohesive energy, the absence of imaginary modes in its phonon spectrum, and the high melting point predicted by molecular dynamics (MD) simulations. Moreover, a particle-swarm optimization (PSO) global minimum search found the Al2C monolayer to be the lowest-energy 2D structure compared to other Al2C alternatives. Dividing the Al2C monolayer results in one-dimensional (1D) Al2C nanoribbons, which are computed to have quite rich characteristics such as direct or indirect band gaps with various values, depending on the direction of the division and the resulting edge configuration.Inspired by our theoretical finding that C2Al62- has a planar D2h minimum with two planar tetracoordinate carbons (ptCs), we computationally designed a new two-dimensional (2D) inorganic material, an Al2C monolayer. All carbons in this monolayer are ptC's, stabilized inductively by binding to four electropositive Al atoms in the same plane. The Al2C monolayer is semiconducting with an indirect minimum band gap and a slightly larger direct band gap. Good persistence of the Al2C monolayer is indicated by its moderate cohesive energy, the absence of imaginary modes in its phonon spectrum, and the high melting point predicted by molecular dynamics (MD) simulations. Moreover, a particle-swarm optimization (PSO) global minimum search found the Al2C monolayer to be the lowest-energy 2D structure compared to other Al2C alternatives. Dividing the Al2C monolayer results in one-dimensional (1D) Al2C nanoribbons, which are computed to have quite rich characteristics such as direct or indirect band gaps with various values, depending on the direction of the division and the resulting edge configuration. Electronic supplementary information (ESI) available: Complete citation of ref. 50, the band structure of an Al2C monolayer computed using the HSE06 functional, snapshots of MD simulations, and bulk structures of Al2C-II and Al2C-III. See DOI: 10.1039/c4nr01972e

Li, Yafei; Liao, Yunlong; Schleyer, Paul Von Ragué; Chen, Zhongfang

2014-08-01

304

Ab initio molecular dynamics of Al irradiation-induced processes during Al{sub 2}O{sub 3} growth  

SciTech Connect

Al bombardment induced structural changes in {alpha}-Al{sub 2}O{sub 3} (R-3c) and {gamma}-Al{sub 2}O{sub 3} (Fd-3m) were studied using ab initio molecular dynamics. Diffusion and irradiation damage occur for both polymorphs in the kinetic energy range from 3.5 to 40 eV. However, for {gamma}-Al{sub 2}O{sub 3}(001) subplantation of impinging Al causes significantly larger irradiation damage and hence larger mobility as compared to {alpha}-Al{sub 2}O{sub 3}. Consequently, fast diffusion along {gamma}-Al{sub 2}O{sub 3}(001) gives rise to preferential {alpha}-Al{sub 2}O{sub 3}(0001) growth, which is consistent with published structure evolution experiments.

Music, Denis; Nahif, Farwah; Friederichsen, Niklas; Schneider, Jochen M. [Materials Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Sarakinos, Kostas [Plasma and Coatings Physics Division, Linkoeping University, SE-58183 Linkoeping (Sweden)

2011-03-14

305

First-principles investigation of mechanical behavior of B2 type aluminides: FeAl and NiAl  

SciTech Connect

First-principles calculations of the elastic constants, shear fault energies, and cleavage strength of NiAl and FeAl are presented. For NiAl, we find that the dissociation of {l angle}111{r angle} superdislocation into partial dislocations is unlikely, due to a high antiphase boundary energy and a weak repulsive elastic force between partial dislocations. FeAl has a high ideal cleavage strength as a result of the directional d-bond formation at the Fe sites. The strong ordering behavior of NiAl is explained in terms of the Al-to-Ni charge transfer and the repulsive interaction between Al atoms. The spontaneous glide decomposition of the {l angle}111{r angle} superdislocation in NiAl is also discussed. 8 refs., 2 figs., 2 tabs.

Fu, C.L.; Yoo, M.H.

1990-01-01

306

Investigation of the low-temperature AlGaN interlayer in AlGaN/GaN/AlGaN double heterostructure on Si substrate  

NASA Astrophysics Data System (ADS)

A low-temperature (LT) AlGaN interlayer is inserted in the Al0.1Ga0.9N back barrier layer of an Al0.2Ga0.8N/GaN/Al0.1Ga0.9N double heterostructure grown on a 150 mm Si substrate. It is found that the 21-nm-thick LT-AlGaN interlayer plays an important role in stress relaxation and dislocation reduction of the Al0.1Ga0.9N back barrier layer, especially for screw dislocation reduction. In addition, a buffer breakdown voltage higher than 600 V is achieved, which is much higher than those of conventional heterostructures. These results demonstrate the effectiveness of combining the LT-AlGaN interlayer and the Al0.2Ga0.8N/GaN/Al0.1Ga0.9N double heterostructure on a Si substrate to increase the breakdown voltage for high-power applications.

Hsiao, Yu-Lin; Wang, Yi-Jie; Chang, Chia-Ao; Weng, You-Chen; Chen, Yen-Yu; Chen, Kai-Wei; Maa, Jer-Shen; Chang, Edward Yi

2014-11-01

307

High temperature stability of multicomponent TiAlSiN and CrAlSiN coatings.  

PubMed

The high temperature oxidation behavior of TiAlSiN and CrAlSiN coatings was studied. These coatings were deposited on silicon substrates by using a cathodic-arc deposition system with lateral rotating arc cathodes. Titanium, chromium and Al88Si12 cathodes were used for the deposition of TiAlSiN and CrAlSiN coatings. All the deposited Ti(0.49)Al(0.44)Si(0.07)N, Ti(0.41)Al(0.51)Si(0.08)N and Cr(0.50)Al(0.440Si(0.06)N coatings showed B1-NaCl crystal structure and possessed nano-grain sizes of 6-8 nm. For the high temperature oxidation test, the coated samples were annealed at 900 degrees C in air for 2 hours. The Ti(0.41)Al(0.51)Si(0.08)N with higher Al and Si contents possessed lower oxidation rate than that of Ti(0.49)Al(0.44)Si(0.07)N. The oxide layer formed on the Ti(0.49)Al(0.44)Si(0.07)N coatings consisted of large TiO2 and TiAlSiN grains at the oxide-coating interface, followed by a layer of Al2O3 in the near-surface region. The oxidation rate of the Cr(0.50)Al(0.44)Si(0.06)N coated sample was much lower than that of the Ti(0.49)Al(0.44)Si(0.07)N and Ti(0.41)Al(0.51)Si(0.08)N. The dense Al2O3 with amorphous top layer at the oxide-coating interface retarded the diffusion of oxygen into the Cr(0.50)Al(0.44)Si(0.06)N. The deposited Cr(0.50)Al(0.44)Si(0.06)N showed a high temperature performance superior to those of the Ti(0.49)Al(0.44)Si(0.07)N and Ti(0.41)Al(0.51)Si(0.08)N. PMID:21128495

Chang, Yin-Yu; Chang, Chi-Pang

2010-07-01

308

Tunneling anisotropic magnetoresistance in Co/AlOx/Al tunnel junctions with fcc Co (111) electrodes  

NASA Astrophysics Data System (ADS)

Tunneling anisotropic magnetoresistance (TAMR) has been characterized in junctions comprised of face-centered cubic (fcc) Co (111) ferromagnetic electrodes grown epitaxially on sapphire substrates, amorphous AlOx tunnel barriers, and nonmagnetic Al counterelectrodes. Large TAMR ratios have been found, up to ˜7.5% and ˜11% (at 5 K), for the in-plane and out-of-plane magnetization geometry, respectively. Such large TAMR values were not expected a priori, given the weak anisotropy of the (bulk) Co bands due to spin-orbit interaction, and the absence of Co (111) surface states that cross the Fermi energy. Both the in-plane and out-of-plane TAMR effects exhibit a predominantly twofold symmetry, and a strong bias dependence. The in-plane TAMR shows a maximum along the (twofold) magnetic hard axis, suggesting a relation between magnetic anisotropy and TAMR. We propose that uniaxial strain in combination with Bychkov-Rashba spin-orbit interaction, producing an interfacial tunneling DOS that depends on the magnetization direction, is responsible for the TAMR effect. The importance of the interfacial Co/AlOx (electronic) structure for the TAMR effect is underlined by measurements on junctions with overoxidized AlOx barriers, which show markedly different bias and angle dependence.

Wang, K.; Tran, T. L. A.; Brinks, P.; Sanderink, J. G. M.; Bolhuis, T.; van der Wiel, W. G.; de Jong, M. P.

2013-08-01

309

A sulfur segregation study of PWA 1480, NiCrAl, and NiAl alloys  

NASA Technical Reports Server (NTRS)

Some nickel based superalloys show reduced oxidation resistance from the lack of an adherent oxide layer during high temperature cyclic oxidation. The segregation of sulfur to the oxide-metal interface is believed to effect oxide adhesion, since low sulfur alloys exhibit enhanced adhesion. X ray Photoelectron Spectroscopy (XPS) was combined with an in situ sample heater to measure sulfur segregation in NiCrAl, PWA 1480, and NiAl alloys. The polished samples with a 1.5 to 2.5 nm (native) oxide were heated from 650 to 1100 C with hold times up to 6 hr. The sulfur concentration was plotted as a function of temperature versus time at temperature. One NiCrAl sulfur study was performed on the same casting used by Browning to establish a base line between previous Auger Electron Spectroscopy (AES) results and the XPS results of this study. Sulfur surface segregation was similar for PWA 1480 and NiCrAl and reached a maximum of 30 at% at 800 to 850 C. Above 900 C the sulfur surface concentration decreased to about 3 at% at 1100 C. These results are contrasted to the minimal segregation observed for low sulfur hydrogen annealed materials which exhibit improved scale adhesion.

Jayne, D. T.; Smialek, J. L.

1993-01-01

310

High Temperature Mechanical Characterization and Analysis of Al2O3 /Al2O3 Composition  

NASA Technical Reports Server (NTRS)

Sixteen ply unidirectional zirconia coated single crystal Al2O3 fiber reinforced polycrystalline Al2O3 was tested in uniaxial tension at temperatures to 1400 C in air. Fiber volume fractions ranged from 26 to 31%. The matrix has primarily open porosity of approximately 40%. Theories for predicting the Young's modulus, first matrix cracking stress, and ultimate strength were applied and evaluated for suitability in predicting the mechanical behavior of Al2O3/Al2O3 composites. The composite exhibited pseudo tough behavior (increased area under the stress/strain curve relative to monolithic alumina) from 22 to 1400 C. The rule-of-mixtures provides a good estimate of the Young's modulus of the composite using the constituent properties from room temperature to approximately 1200 C for short term static tensile tests in air. The ACK theory provides the best approximation of the first matrix cracking stress while accounting for residual stresses at room temperature. Difficulties in determining the fiber/matrix interfacial shear stress at high temperatures prevented the accurate prediction of the first matrix cracking stress above room temperature. The theory of Cao and Thouless, based on Weibull statistics, gave the best prediction for the composite ultimate tensile strength.

Gyekenyesi, John Z.; Jaskowiak, Martha H.

1999-01-01

311

Magnetization anomaly of Nb3Al strands and instability of Nb3Al Rutherford cables  

SciTech Connect

Using a Cu stabilized Nb{sub 3}Al strand with Nb matrix, a 30 meter long Nb{sub 3}Al Rutherford cable was made by a collaboration of Fermilab and NIMS. Recently the strand and cable were tested. In both cases instability was observed at around 1.5 Tesla. The magnetization of this Nb{sub 3}Al strand was measured first using a balanced coil magnetometer at 4.2 K. Strands showed an anomalously large magnetization behavior around at 1.6 T, which is much higher than the usual B{sub c2} {approx} 0.5 Tesla (4.2 K) of Nb matrix. This result is compared with the magnetization data of short strand samples using a SQUID magnetometer, in which a flux-jump signal was observed at 0.5 Tesla, but not at higher field. As a possible explanation for this magnetization anomaly, the interfilament coupling through the thin Nb films in the strands is suggested. The instability problem observed in low field tests of the Nb{sub 3}Al Rutherford cables is attributed to this effect.

Yamada, Ryuji; /Fermilab; Kikuchi, Akihiro; /Tsukuba Magnet Lab; Wake, Masayoshi; /KEK, Tsukuba

2006-08-01

312

AlNb-Based Titanium Aluminide  

NASA Astrophysics Data System (ADS)

The microstructure of laser-tungsten inert gas hybrid welded Ti2AlNb-based joints and their tensile properties at room temperature were investigated in this paper. The results showed that good-quality joints could be obtained by hybrid welding process. The microstructure evolution was identified by means of optical microscopy, scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. The fusion zone mainly consisted of B2 phase due to the rapid cooling rate, as well as high Nb content. The phase compositions of the heat-affected zone were varied with different thermal cycles during the welding process. Tensile tests at room temperature showed that fracture tended to occur in the fusion zone, and the tensile strength and elongation were 950 MPa and 4.3%, respectively. The fracture mode was quasi-cleavage based on the observation of the fracture morphology.

Zhang, Kezhao; Liu, Ming; Lei, Zhenglong; Chen, Yanbin

2014-10-01

313

An elliptical wiggler beamline for the ALS  

SciTech Connect

A beamline for circularly polarized radiation produced by an elliptical wiggler has been designed at the ALS covering the broad energy range from 50 eV to 2000 eV. The rigorous theory of grating diffraction efficiency has been used to maximize transmitted flux. The nature of the elliptical wiggler insertion device creates a challenging optical problem due to the large source size in the vertical and horizontal directions. The requirement of high resolving power, combined with the broad tuning range and high heat loads complicate the design. These problems have been solved by using a variable included angle monochromator of the ``constant length`` type with high demagnification onto its entrance slit, and cooled optics.

Martynov, V.V. [Lawrence Berkeley Lab., CA (United States)]|[Inst. of Microelectronics Technology, Chernogolovka (Russia); McKinney, W.R.; Padmore, H.A. [Lawrence Berkeley Lab., CA (United States)

1995-10-01

314

Thermal cycling of AlTiN- and AlTiON-coated hot work tool steels at elevated temperatures  

Microsoft Academic Search

The principle failure mechanism in thixoforming dies is thermal fatigue as the mechanical loading on the tooling is modest owing to a mushy feedstock. X32CrMoV33 hot work tool steel samples coated with AlTiN and AlTiON via Cathodic Arc Physical Vapour Deposition were submitted to thermal cycling under conditions which mimic thixoforming of steels. While the AlTiN and AlTiON coatings provide

Yucel Birol; Duygu ?sler

2011-01-01

315

27Al Multiple-Quantum MAS NMR of Mechanically Treated Bayerite (?-Al(OH) 3) and Silica Mixtures  

Microsoft Academic Search

Two-dimensional 27Al multiple-quantum magic angle spinning (MQMAS) NMR experiments are used to study mixtures of bayerite (?-Al(OH)3) with either silicic acid (SiO2.nH2O) or silica gel (SiO2) that have been ground together for varying lengths of time. This mechanical treatment produces changes in the 27Al MAS and MQMAS NMR spectra that correspond to the formation of new Al species. Mean values

Sharon E. Ashbrook; Kenneth J. D. MacKenzie; Stephen Wimperis

2001-01-01

316

Mg-Al Sapphirine and Ca-Al Hibonite-bearing Granulite Xenoliths from the Chyulu Hills Volcanic Field, Kenya  

Microsoft Academic Search

Basanites of the Chyulu Hills (Kenya Rift) contain mafic Mg-Al and Ca-Al granulite xenoliths. Their protoliths are interpreted as troctolitic cumulates; however, the original mineral assemblages were almost completely transformed by subsolidus reactions. Mg-Al granulites contain the minerals spinel, sapphirine, sillimanite, plagioclase, corundum, clinopyroxene, orthopyroxene and garnet, whereas Ca-Al granulites are characterized by hibonite, spinel, sapphirine, mullite, sillimanite, plagioclase, quartz,

A. ULIANOV; A. KALT

2006-01-01

317

Sintering, microstructure and properties of WC-FeAlB and WC-Ni3AlB composite materials  

Microsoft Academic Search

The effect of boron on microstructure and mechanical properties of the intermetallic matrix composites (WC-FeAl-B and WC-Ni3Al-B) were investigated. The results were compared with those obtained from WC-Co composite which had same binder volume fraction and fabricated under identical sintering conditions. Boron doped FeAl (FeooA14o) and NhAl alloys were selected as potential new alternative binders in place of cobalt for

Mehdi Ahmadian-Najafabadi

2005-01-01

318

The effect of Al content on the galvanic corrosion behaviour of coupled Ni\\/graphite and Ni–Al coatings  

Microsoft Academic Search

In this study, the corrosion behaviour of 75Ni\\/25graphite abradable coating and Ni–Al bonding coatings with different Al content were investigated with open circuit potential and polarization tests. The galvanic corrosion of the coupled Ni\\/graphite and Ni–Al coatings was studied by using a zero-resistance ammeter in 5wt% NaCl solution. The experimental results showed that the corrosion resistance of the Ni–Al coatings

Cunguan Xu; Lingzhong Du; Bin Yang; Weigang Zhang

2011-01-01

319

Atomistic calculations of hydrogen interactions with Ni3Al grain boundaries and Ni\\/Ni\\/Ni3Al interfaces  

Microsoft Academic Search

Embedded Atom Method (EAM) potentials have been developed for the Ni\\/Al\\/H system. The potentials have been fit to numerous properties of this system. For example, these potentials represent the structural and elastic properties of bulk Ni, Al, Ni3Al, and NiAl quite well. In addition the potentials describe the solution and migration behavior of hydrogen in both nickel and aluminum. A

M. I. Baskes; J. E. Angelo; N. R. Moody

1995-01-01

320

Adhesion, Atomic Structure, and Bonding at the Al2O3(0001)/Al(111) Interface: A First Principles Study  

E-print Network

Adhesion, Atomic Structure, and Bonding at the «­Al2O3(0001)/Al(111) Interface: A First Principles ), and bond character of the «­Al2O3(0001)/Al(111) interface. A total of six candidate interface structures, and have determined that a major contribution to bonding across the interface is simi- lar to what is found

Adams, James B

321

The Low-Lying States of AlCu and AlAg  

NASA Technical Reports Server (NTRS)

The singlet and triplet states of AlCu and AlAg below about 32 000/cm are studied using the internally contracted multireference configuration-interaction method. A more elaborate study of the X(sup 1)Sum(sup +) ground state of AlCu is undertaken using extended Gaussian basis sets, including the effect of inner-shell correlation and including a perturbational estimate of relativistic effects. Our best estimate of the spectroscopic constants (r(sub 0), DeltaG(sub 1/2), and D(sub 0)) for the X(sup 1)Sum(sup+) state with the experimental values in parentheses are: 4.416(4.420) a(sub 0), 295 (294) /cm, and 2.318 (2.315) eV. The calculations definitively assign the upper state in the observed transition at 14 892/cm to the lowest (sup 1)Prod state. The calculated spectroscopic constants and radiative lifetime for the (sup 1)Prod state are in good agreement with experiment. The calculations support the tentative assignments of Behm et al. for three band systems observed in the visible region between 25 000 and 28 000 / cm. However, the computed spectroscopic constants are in very poor agreement with those deduced from an analysis of the spectra. Analogous theoretical results for AlAg suggest that the (2)(sup 3)Prod, (3)(sup 3)Prod, and (3)(sup 1)Sum(sup +) states account for the bands observed, but not assigned, by Duncan and co-workers.

Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry

1994-01-01

322

Infiltration of Saffil alumina fiber with AlCu and AlSi alloys  

SciTech Connect

Currently there is a considerable scientific and technological interest in the composite materials, which a strong ceramic reinforcement is incorporated into a metal matrix (MMC) to tailor its properties for specific applications. Among the various techniques for fabricating MMC, the liquid metal infiltration process by means of a pressurized gas is an attractive fabrication route for near net shaped metal matrix composite and has been successfully used to fabricate Al, Mg and more recently, Ni and Ni aluminide matrix composites, which can be reinforced by SiC or Al[sub 2]O[sub 3] particles, whiskers, or short fibers. This paper describes the experimental technique used and presents an experimental investigation of the effects of the process parameters employed, such as the preform and melt temperatures, the volume fraction of fibers in the preform and the applied pressure upon the infiltration length of a chopped preform during a unidirectional infiltration aided by gas pressure casting. The experiments of the present work were conducted to provide kinetic data with a view to optimizing the selection of the process initial conditions for infiltration which have an effect on the infiltration length of the molten matrix alloy into a preform and it is a first step in investigating the correlation between the infiltration length (fluidity) of AlCuSi matrix alloys and the microstructure of the composites fabricated by pressure casting. For this purpose, this paper focuses on AlCu and AlSi matrix alloys reinforced by short-fibers [delta]-alumina SAFFIL. The experiments reported here were performed with the fibers initially at a temperature significantly below the metal melting point. This is the case of practical interest for the fabrication of many fiber-reinforced metal components.

Garbellini, O.; Morando, C.; Biloni, H.; Palacio, H. (Comision de Investigaciones Cientificas de la Provincia de Buenos Aires, Tandil (Argentina). Inst. de Fisica de Materiales)

1999-06-18

323

Surface structures of Al-Pd-Mn and Al-Cu-Fe icosahedral quasicrystals  

SciTech Connect

In this dissertation, the author reports on the surface structure of i-Al-Pd-Mn twofold, threefold, fivefold and i-Al-Cu-Fe fivefold surfaces. The LEED studies indicate the existence of two distinct stages in the regrowth of all four surfaces after Ar{sup +} sputtering. In the first stage, upon annealing at relatively low temperature: 500K--800K (depending on different surfaces), a cubic phase appears. The cubic LEED patterns transform irreversibly to unreconstructed quasicrystalline patterns upon annealing to higher temperatures, indicating that the cubic overlayers are metastable. Based upon the data for three chemically-identical, but symmetrically-inequivalent surfaces, a model is developed for the relation between the cubic overlayers and the quasicrystalline substrate. The model is based upon the related symmetries of cubic close-packed and icosahedral-packed materials. These results may be general among Al-rich, icosahedral materials. STM study of Al-Pd-Mn fivefold surface shows that terrace-step-kink structures start to form on the surface after annealing above 700K. Large, atomic ally-flat terraces were formed after annealing at 900K. Fine structures with fivefold icosahedral symmetry were found on those terraces. Data analysis and comparison of the STM images and structure model of icosahedral Al-Pd-Mn suggest that the fine structures in the STM images may be the pseudo Mackay (PMI) clusters which are the structure units of the structure model. Based upon his results, he can conclude that quasicrystalline structures are the stable structures of quasicrystal surfaces. In other words, quasicrystalline structures extend from the bulk to the surface. As a result of the effort reported in this dissertation, he believes that he has increased his understanding of the surface structure of icosahedral quasicrystals to a new level.

Shen, Z.

1999-02-12

324

Tribological properties of thermally sprayed TiAl-Al2O3 composite coating  

NASA Astrophysics Data System (ADS)

The use of thermal spray coatings provides protection to the surfaces operating in severe environments. The main goal of the current work is to investigate the possibility of using a high velocity oxy fuel (HVOF) thermally sprayed wear resistant TiAl/Al2O3 coating on tool steel (H13) which is used for making dies for aluminium high pressure die casting. A feedstock of TiAl/Al2O3 composite powder was produced from a mixture of Al and TiO2 powders by high energy mechanical milling, followed by a thermal reaction process. The feedstock was then thermally sprayed using a high velocity oxy-fuel (HVOF) technique onto H13 steel substrates to produce a composite coating. The present study describes and compares the tribological properties such as friction and sliding wear rate of the coating both at room and high temperature (700°C). The results showed that the composite coating has lower wear rate at high temperature (700°C) than the uncoated H13 sample. At Room temperature without using lubricant there is no much significant difference between the wear rate of the coated and uncoated samples. The experimental results showed that the composite coating has great potential for high temperature application due to its lower wear rate at high temperature in comparison with the uncoated sample at the same temperature. The composite coating was characterized using scanning electron microscopy (SEM), optical microscopy and X-ray diffractometry (XRD). This paper reports the experimental observations and discusses the wear resistance performance of the coatings at room and high temperatures.

Salman, A.; Gabbitas, B.; Li, J.; Zhang, D.

2009-08-01

325

Preparation and characterization of Al/Al2O3/Cu SIN tunnel junctions microfabricated with a full wafer process  

E-print Network

, alignment accuracy, and topological flexibility compared to shadow masking techniques. Initially we built Al. Barrier formation is very well controlled and virtually immune to contamination. The key requirements deposition system is a load-locked UHV sputtering system. We are developing our Al/Al 2 O 3 /Cu full wafer

Neuhauser, Barbara

326

Exposure Histories of Shergottites Dar Al Gani 476/489/670/735 and Sayh Al Uhaymir 005  

NASA Astrophysics Data System (ADS)

We measured cosmogenic nuclides, ^14C, ^36Cl, ^26Al, and ^10Be in Dar al Gani 476, 489, 670, and 735 and Sayh al Uhaymir 005 basaltic shergottites. The exposure ages and terrestrial ages of these Martian meteorites were investigated.

Nishiizumi, K.; Caffee, M. W.; Jull, A. J. T.; Klandrud, S. E.

2001-03-01

327

Exposure History of Shergottites Dar Al Gani 476/489/670/735 and Sayh Al Uhaymir 005  

NASA Technical Reports Server (NTRS)

We measured cosmogenic nuclides, C-14, Cl-36, Al-26, and Be-10 in Dar al Gani 476, 489, 670, and 735 and Sayh al Uhaymir 005 basaltic shergottites. The exposure ages and terrestrial ages of these martian meteorites were investigated. Additional information is contained in the original extended abstract.

Nishiizumi, K.; Caffee, M. W.; Jull, A. J. T.; Klandrud, S. E.

2001-01-01

328

THE NEXT ALS BREAKTHROUGH COULD BE YOURS Prize4Life Awards Prizes for ALS Biomarker Challenge to InnoCentive  

E-print Network

. ALS, commonly known in the US as Lou Gehrig's disease, is a rapidly progressing neurodegenerativeTHE NEXT ALS BREAKTHROUGH COULD BE YOURS Prize4Life Awards Prizes for ALS Biomarker Challenge - InnoCentive, Inc., the global open innovation marketplace, and Prize4Life, a non-profit organization

Grishok, Alla

329

Crystal structure of novel compounds in the systems Zr-Cu-Al, Mo-Pd-Al and partial phase equilibria in the Mo-Pd-Al system.  

PubMed

The crystal structures of three Al-rich compounds have been solved from X-ray single crystal diffractometry: ?(1)-MoPd(2-x)Al(8+x) (x = 0.067); ?(7)-Zr(Cu(1-x)Al(x))(12) (x = 0.514) and ?(9)-ZrCu(1-x)Al(4) (x = 0.144). ?(1)-MoPd(2-x)Al(8+x) adopts a unique structure type (space group Pbcm; lattice parameters a = 0.78153(2), b = 1.02643(3) and c = 0.86098(2) nm), which can be conceived as a superstructure of the Mo(Cu(x)Al(1-x))(6)Al(4) type. Whereas Mo-atoms occupy the 4d site, Pd(2) occupies the 4c site, Al and Pd(1) atoms randomly share the 4d position and the rest of the positions are fully occupied by Al. A Bärnighausen tree documents the crystallographic group-subgroup relation between the structure types of Mo(Cu(x)Al(1-x))(6)Al(4) and ?(1). ?(7)-Zr(Cu(1-x)Al(x))(12) (x = 0.514) has been confirmed to crystallize with the ThMn(12) type (space group I4/mmm; lattice parameters a = 0.85243(2) and c = 0.50862(3) nm). In total, 4 crystallographic sites were defined, out of which, Zr occupies site 2a, the 8f site is fully occupied by Cu, the 8i site is entirely occupied by Al, but the 8j site turned out to comprise a random mixture of Cu and Al atoms. The compound ?(9)-ZrCu(1-x)Al(4) (x = 0.144) crystallizes in a unique structure type (space group P4/nmm; lattice parameters a = 0.40275(3) and c = 1.17688(4) nm) which exhibits full atom order but a vacancy (14.4%) on the 2c site, shared with Cu atoms. ?(9)-ZrCu(1-x)Al(4) is a superstructure of Cu with an arrangement of three unit cells of Cu in the direction of the c-axis. A Bärnighausen tree documents this relationship. The ZrCu(1-x)Al(4) type (n = 3) is part of a series of structures which follow this building principle: Cu (n = 1), TiAl(3) (n = 2), ?(5)-TiNi(2-x)Al(5) (n = 4), HfGa(2) (n = 6) and Cu(3)Pd (n = 7). A partial isothermal section for the Al-rich part of the Mo-Pd-Al system at 860 °C has been established with two ternary compounds ?(1)-MoPd(2-x)Al(8+x) and ?(2) (unknown structure). The Vickers hardness (H(v)) for ?(1) was found to be 842 ± 40 MPa. PMID:22183686

Khan, Atta U; Rogl, P; Giester, G

2012-02-28

330

Overview of the development of FeAl intermetallic alloys  

SciTech Connect

B2-phase FeAl ordered intermetallic alloys based on an Fe-36 at.% Al composition are being developed to optimize a combination of properties that includes high-temperature strength, room-temperature ductility, and weldability. Microalloying with boron and proper processing are very important for FeAl properties optimization. These alloys also have the good to outstanding resistance to oxidation, sulfidation, and corrosion in molten salts or chlorides at elevated temperatures, characteristic of FeAl with 30--40 at.% Al. Ingot- and powder-metallurgy (IM and PM, respectively) processing both produce good properties, including strength above 400 MPa up to about 750 C. Technology development to produce FeAl components for industry testing is in progress. In parallel, weld-overlay cladding and powder coating technologies are also being developed to take immediate advantage of the high-temperature corrosion/oxidation and erosion/wear resistance of FeAl.

Maziasz, P.J.; Liu, C.T.; Goodwin, G.M.

1995-09-01

331

A trilayer process for the fabrication of Al phase qubits  

NASA Astrophysics Data System (ADS)

Herein we develop an Al/AlO x /Al trilayer process, feasible to fabricate complex circuits with wiring crossovers, for the preparation of Al junctions and phase qubits. The AlO x layer is obtained by in situ thermal oxidation, which provides high-quality junction tunnel barriers. The Al junctions show a considerably low leakage current and the Josephson critical current density can be conveniently controlled in the range of a few to above 100 A/cm2, which is favorable in the phase qubit application. Macroscopic quantum tunneling, energy spectrum, energy relaxation time, Rabi oscillation, and Ramsey interference of the Al phase qubits are measured, demonstrating clearly quantum coherent dynamics with a timescale of 10 ns. Further improvements of the coherent dynamic properties of the device are discussed.

Xue, GuangMing; Yu, HaiFeng; Tian, Ye; Deng, Hui; Liu, WeiYang; Ren, YuFeng; Yu, HongWei; Zheng, DongNing; Zhao, ShiPing

2013-12-01

332

The Role of PentaCoordinated Al3+ Ions in the High Temperature Phase Transformation of ?-Al2O3  

SciTech Connect

In this work, the structural stability of gamma-alumina (?-Al2O3) was investigated by a combination of XRD and high resolution solid state 27Al MAS NMR at an ultra-high magnetic field of 21.1 tesla. XRD measurements show that ?-Al2O3 undergoes a phase transition to ?-Al2O3 during calcination at 1000oC for 10hr. The formation of the ?-Al2O3 phase is further confirmed by 27Al MAS NMR; additional 27Al peaks centered at 10.5 and ~78 ppm were observed in samples calcined at this high temperature. Both the XRD and NMR results indicate that, after calcination at 1000°C for 10 hrs, the ratio of the ?-Al2O3 phase to the total alumina in samples modified by either BaO or La2O3 is significantly reduced in comparison with ?-Al2O3. 27Al MAS NMR spectra revealed that the reduction in the extent of ?-Al2O3 formation was highly correlated with the reduction in the amount of penta-coordinated aluminum ions, measured after 500°C calcination, in both BaO- and La2O3-modified ?-Al2O3 samples. These results strongly suggest that the penta-coordinated aluminum ions, present exclusively on the surface of ?-Al2O3, play a critical role in the phase transformation of ?-Al2O3 to ?-Al2O3. The role of the modifiers, in our case BaO or La2O3, is to convert the penta-coordinated aluminum ions into octahedral ones, thereby improving the thermal stabilities of the samples. Oxide additives, on the other hand, had no beneficial effect on preventing the specific surface area reduction that occurred during high temperature (?1000°C) calcination.

Kwak, Ja Hun; Hu, Jian Zhi; Lukaski, Adrienne C.; Kim, Do Heui; Szanyi, Janos; Peden, Charles HF

2008-06-26

333

76 FR 78717 - In the Matter of the Designation of Saleh al-Qarawi also known as Saleh Al Qarawi also known as...  

Federal Register 2010, 2011, 2012, 2013

...known as Saleh Abudullah Saleh Al Qarawi also known as Saleh bin Abdullah al-Qarawi also known as Akhuk al Saghir also known...known as Saleh Abudullah Saleh Al Qarawi, also known as Saleh bin Abdullah al-Qarawi, also known as Akhuk al Saghir, also...

2011-12-19

334

77 FR 61046 - The Amendment of the Designation of Al-Qa'ida in the Arabian Peninsula, aka Al-Qa'ida of Jihad...  

Federal Register 2010, 2011, 2012, 2013

...of the Designation of Al-Qa'ida in the Arabian Peninsula, aka Al-Qa'ida of Jihad Organization in the Arabian Peninsula, aka Tanzim Qa'idat al-Jihad fi Jazirat al-Arab, aka Al- Qa'ida in Yemen, aka Al-Qa'ida in the...

2012-10-05

335

77 FR 61046 - The Review and Amendment of the Designation of Al-Qa'ida in the Arabian Peninsula, aka Al-Qa'ida...  

Federal Register 2010, 2011, 2012, 2013

...of the Designation of Al-Qa'ida in the Arabian Peninsula, aka Al-Qa'ida of Jihad Organization in the Arabian Peninsula, aka Tanzim Qa'idat al-Jihad fi Jazirat al-Arab, aka Al- Qa'ida in Yemen, aka Al-Qa'ida in the...

2012-10-05

336

Creep deformation of a two-phase TiAl/Ti[sub 3]Al lamellar alloy and the individual TiAl and Ti[sub 3]Al constituent phases  

SciTech Connect

Two-phase TiAl/Ti[sub 3]Al alloys in which the constituent phases form a lamellar microstructure are reported to possess good combinations of low-temperature fracture toughness, tensile strength and fatigue resistance. However, information about the high-temperature creep properties of the two-phase TiAl/Ti[sub 3]Al alloys with lamellar microstructures (referred to as lamellar alloys in the remainder of the paper) is limited. Based on a simple rule of mixtures model of strength, it would be expected that the creep rates of the lamellar alloy would be between the creep rates of TiAl and Ti[sub 3]Al. In contrast to composite model predictions of strength, Polvani and coworkers found that the minimum creep rates of two duplex alloys, a [gamma]/[gamma][prime] nickel-base superalloy and NiAl/Ni[sub 2]AlTi, were significantly lower than the minimum creep rates of either of the constituent phases. They also reported that most dislocations in the two-phase NiAl/Ni[sub 2]AlTi alloy were contained within the semi-coherent interfacial dislocation networks between the two phases. Based on this observation they proposed that the creep rate is controlled by the rate at which dislocations moving through both phases are emitted and absorbed by the interphase dislocation networks. The greater strain hardening rate of the lamellar TiAl/Ti[sub 3]Al alloy suggests that it may exhibit lower steady-state creep rates that the individual constituent phases. The objective of the present study is to evaluate the creep properties of a TiAl/ Ti[sub 3]Al lamellar alloy and of the individual constituent phases. In this paper, the results of this investigation will be presented and compared with previously published results for this alloy system.

Bartholomeusz, M.F.; Wert, J.A. (Univ. of Virgina, Charlottesville, VA (United States)); Qibin Yang (Inst. of Metals Research, Shenyang (China))

1993-08-01

337

Formation of (H+, Al+, Al2+) co-doped bayerite and gamma-Al2O3 plates from spinel-type related nanocondensates in water.  

PubMed

The Al2O3 nanocondensates of spinel-type related structures, i.e., gamma- and theta-type with a significant internal compressive stress via pulsed laser ablation in water were subjected to prolonged dwelling in water to form columnar bayerite plates for further transformation as platy gamma-Al2O3. Transmission electron microscopic observations indicated the gamma-Al2O3 follows the crystallographic relationship (100)b//(011)gamma; [001]b//[111]gamma with relic bayerite (denoted as b). The gamma-Al2O3 also shows {111} twin/faults and rock salt-type domains due to dehydroxylation of bayerite which involves {1111} shuffling and disordering of the Al ions in the octahedral and tetrahedral sites. The combined evidences of X-ray photoelectron spectroscopy, vibrational spectroscopy and UV-visible absorbance indicated that the H+, Al+ and Al2+ co-doped bayerite and gamma-Al2O3 composite plates have a minimum band gap as low as approximately 5 eV for potential catalytic and electro-optical applications in water environment. PMID:21446423

Liu, I-Lung; Chen, Shuei-Yuan; Shen, Pouyan

2011-01-01

338

Structure, Energetics, Electronic, and Hydration Properties of Neutral and Anionic Al3O6, Al3O7, and Al3O8 Clusters  

E-print Network

-coordinated Al sites. I. Introduction Aluminum oxide, Al2O3, traditionally referred to as alumina, is a very material rests primarily on its extreme hardness (15 Gpa), high melting point (2327 K), and low electrical conductivity (10-12 S/m at 20 °C). It has a wide range of applications, from electronics, optics, biomedical

Pandey, Ravi

339

Measured Activities of Al and Ni in gamma-(Ni) and gamma'-(Ni)3Al in the Ni-Al-Pt System  

NASA Technical Reports Server (NTRS)

Adding Pt to Ni-Al coatings is critical to achieving the required oxidation protection of Ni-based superalloys, but the nature of the Pt effect remains unresolved. This research provides a fundamental part of the answer by measuring the influence of Pt on the activities of Al and Ni in gamma-(Ni), gamma prime-(Ni)3Al and liquid in the Ni-Al-Pt system. Measurements have been made at 25 compositions in the Ni-rich corner over the temperature range, T = 1400-1750 K, by the vapor pressure technique with a multiple effusion-cell mass spectrometer (multi-cell KEMS). These measurements clearly show adding Pt (for X(sub Pt) less than 0.25) decreases a(Al) while increasing a(Ni). This solution behavior supports the idea that Pt increases Al transport to an alloy / Al2O3 interface and also limits the interaction between the coating and substrate alloys in the gamma-(Ni) + gamma prime-(Ni)3Al region. This presentation will review the progress of this study.

Copland, Evan

2007-01-01

340

Crystal structure and negative magnetization in Sm2Al and Sm1.988Gd0.012Al compounds  

NASA Astrophysics Data System (ADS)

Here we report Sm2Al and Sm1.988Gd0.012Al compounds, with orthorhombic crystal structure (space group: Pnma), showing negative magnetization in temperature dependence magnetization data. Both compounds magnetically order at ~150 and 200 K respectively and below this temperature, magnetization data shows a compensation temperature (Tcomp) which shifts with field. Hysteresis loops obtained below Tcomp signify that both Sm2Al and Sm1.988Gd0.012Al possess exchange anisotropy. Both, exchange anisotropy field and coercive field are found to be quite large and comparable to those of the classical spin-orbit compensated ferromagnet (Sm,Gd)Al2.

Kumar, Pramod; Kumar, Rachana; Pandey, S.; Suresh, K. G.; Nigam, A. K.

2014-09-01

341

Effect of dislocations on electron mobility in AlGaN/GaN and AlGaN/AlN/GaN heterostructures  

SciTech Connect

Al{sub x}Ga{sub 1-x}N/GaN (x = 0.06, 0.12, 0.24) and AlGaN/AlN/GaN heterostructures were grown on 6 H-SiC, GaN-on-sapphire, and free-standing GaN, resulting in heterostructures with threading dislocation densities of {approx}2 Multiplication-Sign 10{sup 10}, {approx}5 Multiplication-Sign 10{sup 8}, and {approx}5 Multiplication-Sign 10{sup 7} cm{sup -2}, respectively. All growths were performed under Ga-rich conditions by plasma-assisted molecular beam epitaxy. Dominant scattering mechanisms with variations in threading dislocation density and sheet concentration were indicated through temperature-dependent Hall measurements. The inclusion of an AlN interlayer was also considered. Dislocation scattering contributed to reduced mobility in these heterostructures, especially when sheet concentration was low or when an AlN interlayer was present.

Kaun, Stephen W.; Burke, Peter G.; Kyle, Erin C. H.; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Wong, Man Hoi; Mishra, Umesh K. [Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States)

2012-12-24

342

Growth of crystallized AlOx on AlN/GaN heterostructures by in-situ RF-MBE  

NASA Astrophysics Data System (ADS)

We report successful growth of a crystallized AlOx layer on top of AlN/GaN heterostructures by using RF-plasma molecular-beam epitaxy for exploring a new-type oxide/nitride heterostructure system. The insertion of an AlOx buffer layer, which was formed by following three steps of (i) an Al metal deposition at 150 °C, (ii) an oxidation of the Al metal by oxygen plasma irradiation, and (iii) an annealing of the oxidized layer at 800 °C, facilitated the formation of a crystalline AlOx layer on top of the AlN/GaN structures. Surface morphologies observed by atomic force microscope showed that the AlOx buffer layer was directly formed on the nitride structure and fully covered the AlN layer. The AlOx top layer grown on the buffer layer had a flat and smooth surface. A cross-sectional transmission electron microscopy micrograph revealed that the AlOx thin film grown at 800 °C on the nitride structure was fully crystallized.

Sugiura, Yohei; Honda, Tohru; Higashiwaki, Masataka

2014-11-01

343

Thermodynamic stability and point defects of {gamma}-TiAl and the phase relationships of Ti-Al  

SciTech Connect

Thermodynamic model parameters of the nine phases in the Ti-Al system were obtained by optimization using thermodynamic and phase equilibrium data existing in the literature. These phases are liquid, {alpha}-(Ti,Al), {beta}-(Ti,Al), (Al), {alpha}{sub 2}-Ti{sub 3}Al, {gamma}-TiAl, TiAl{sub 3}, TiAl{sub 2} and Ti{sub 2}Al{sub 5}. The Redlich-Kister equation was used to represent the excess Gibbs energy for the first four phases; the generalized quasi-chemical model recently formulated by them, for the next three phases; and the last two phases were treated as stoichiometric phases or line compounds. Thermodynamic values obtained from the model parameters as well as the calculated phase diagram are in agreement with the experimental data within the uncertainties of the data. The intrinsic defect concentrations obtained from the model parameters for {gamma}-TiAl are in accordance with values predicted from an independent relationship between the defect concentration and the enthalpy of formation. Since defect concentrations predicted from a similar relationship for anti-structure B2 phases are in accord with experimental values, it is reasonable to expect that the model-calculated values for {gamma}-TiAl are physically realistic.

Zhang, F.; Chen, S.L.; Chang, Y.A. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering; Kattner, U.R. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

1995-12-31

344

Formation and Thermodynamics of Mg-Al-Ti-O Complex Inclusions in Mg-Al-Ti-Deoxidized Steel  

NASA Astrophysics Data System (ADS)

The formation of Mg-Al-Ti-O complex inclusions in steel was investigated by laboratory experiments and thermodynamic calculation. The composition evolutions of Mg-Al-Ti-O inclusions in steel with different contents of [Al], [Mg], and [Ti] were discussed. Mg-Al-Ti-O complex inclusion with high TiO x content was liquid at 1873 K (1600 °C), indicating MgAl2O4 spinel inclusions can be modified to low melting temperature ones by combining TiO x component. The stability diagram of Al-Mg-Ti-O system inclusions in the molten steel at 1873 K (1600 °C) was calculated, considering many kinds of oxide inclusions such as MgO, Al2O3, TiO x , MgTi2O4, MgAl2O4, Al2TiO5, and liquid inclusion. The thermodynamic calculations are in good agreement with experimental results, which can predict the formation of Al-Mg-Ti-O complex inclusions in molten steel with a large concentration range of [Al], [Mg], and [Ti].

Ren, Ying; Zhang, Lifeng; Yang, Wen; Duan, Haojian

2014-08-01

345

Effect of Silicate on the Formation and Stability of Ni-Al LDH at the ?-Al2O3 Surface.  

PubMed

The formation of mixed metal precipitates has been identified as a significant mechanism for the immobilization and elimination of heavy metal ions. Silicate is present in natural systems ubiquitously, which may interfere with metal uptake on the mineral surface and thereby influences the solubility of the precipitate. Herein, kinetic sorption and dissolution experiments combined with extended X-ray absorption fine structure spectroscopy (EXAFS) were performed to elucidate the effect of silicate on the formation of Ni precipitates at the ?-Al2O3 surfaces. The uptake of Ni on ?-Al2O3 decreased with increasing amounts of silicate coated onto the ?-Al2O3 surface. Results of EXAFS analyses suggested the formation of Ni-Al layered double hydroxide (LDH) phases. The surface coating of silicate on ?-Al2O3 reduced Al release and finally resulted in a high Ni:Al ratio due to a lower extent of Al substitution into the precipitates. The presence of silicate prevented the growth of the precipitates and led to the formation of less stable Ni-Al LDH. The influence of silicate on the precipitate formation provided the evidence for the growth relationship between the precipitate and mineral substrate in the real environment. Increased rates of proton-promoted dissolution of Ni surface precipitates were mainly attributed to higher Ni:Al ratios in Ni-Al LDH precipitates formed in the presence of silicate. PMID:25339547

Tan, Xiaoli; Fang, Ming; Ren, Xuemei; Mei, Huiyang; Shao, Dadong; Wang, Xiangke

2014-11-18

346

Erosion resistance of FeAl-TiB{sub 2} and FeAl-WC at room and elevated temperatures  

SciTech Connect

The resistance of FeAl-40%TiB{sub 2} and FeAl-80%WC cermets to solid particle erosion at 25, 180, 500 and 700 C was evaluated and compared to the behavior of WC-6%Co (Co-90%WC) cemented carbides. Even though the WC-Co contained a higher volume fraction of the hard phase, the erosion rates of the FeAl-cermets were similar in magnitude to the erosion rates of the WC-Co. However, the erosion rates of the FeAl-cermets either were constant (FeAl-TiB{sub 2}) or decreased (FeAl-WC) with increasing test temperature; whereas, the erosion rates of the WC-Co cemented carbides increased with increasing test temperature. This indicated that once the microstructures of the FeAl-cermets are optimized for wear resistance, these materials might make promising candidates for high-temperature wear applications.

Alman, D.E.; Tylczak, J.H.; Hawk, J.A.

2000-01-01

347

Erosion resistance of FeAl-TiB[sub 2] and FeAl-WC at room and elevated temperatures  

SciTech Connect

The resistance of FeAl-40%TiB[sub 2] and FeAl-80%WC cermets to solid particle erosion at 25, 180, 500 and 700 C was evaluated and compared to the behavior of WC-6%Co (Co-90%WC) cemented carbides. Even though the WC-Co contained a higher volume fraction of the hard phase, the erosion rates of the FeAl-cermets were similar in magnitude to the erosion rates of the WC-Co. However, the erosion rates of the FeAl-cermets either were constant (FeAl-TiB[sub 2]) or decreased (FeAl-WC) with increasing test temperature; whereas, the erosion rates of the WC-Co cemented carbides increased with increasing test temperature. This indicated that once the microstructures of the FeAl-cermets are optimized for wear resistance, these materials might make promising candidates for high-temperature wear applicati2048

David E. Alman; Joseph H. Tylczak; Jeffrey A. Hawk

2000-01-01

348

Internal stress superplasticity in directionally solidified Al-Al{sub 3}Ni eutectic composite  

SciTech Connect

Thermal cycling creep behavior in fiber-reinforced composites was investigated using a directionally solidified Al-Al{sub 3}Ni eutectic composite. A superplastic elongation of 120% was obtained during a thermal cycling tensile creep test. Compression creep tests were performed under an external stress applied either parallel or perpendicular to the growth direction. The average strain rates for the two directions exhibited the characteristics of internal stress superplasticity: those at low stresses were much higher than the corresponding isothermal creep rates and were proportional to the applied stress. In the case of transverse loading, the thermal cycling creep rate was explained quantitatively using the previously reported internal stress superplasticity model for particle-dispersed composite. In the case of longitudinal loading, it was much lower than that predicted using the model because of the difference in the stress state and the relaxation process. However, thermal cycling creep had very low activation energy, which is a unique characteristic of internal stress superplasticity.

Kitazono, K. [Inst. of Space and Astronautical Science, Sagamihara, Kanagawa (Japan)] [Inst. of Space and Astronautical Science, Sagamihara, Kanagawa (Japan); [Univ. of Tokyo, Hongo, Bunkyo (Japan). Dept. of Materials Science; Sato, E. [Inst. of Space and Astronautical Science, Sagamihara, Kanagawa (Japan)] [Inst. of Space and Astronautical Science, Sagamihara, Kanagawa (Japan)

1998-12-11

349

Removing Al and regenerating caustic soda from the spent washing liquor of Al etching  

NASA Astrophysics Data System (ADS)

Spent liquor from washing of aluminum section materials after etching with caustic soda (NaOH) has been treated. Aluminum was removed from the liquor and caustic soda was regenerated by adding precipitating agents to hydrolyze sodium aluminate (Na2AlO2), separating the aluminumprecipitate, and concentrating free NaOH in the resulting solution for reuse in the etching process. Four systems were investigated: hydrated lime [Ca(OH)2], hydrogen peroxide (H2O2), H2O2/Ca(OH)2 mixture, and dry lime (CaO). Results revealed that CaO was more efficient in the removal of aluminum from the spent liquor with a higher hydrolyzing rate of Na2AlO2 than Ca(OH)2, H2O2, or their mixture.

Barakat, M. A.; El-Sheikh, S. M.; Farghly, F. E.

2005-08-01

350

Kinetic energy distributions of sputtered neutral aluminum clusters: Al--Al[sub 6  

SciTech Connect

Neutral aluminum clusters sputtered from polycrystalline aluminum were analyzed by laser postionization time-of-flight (TOF) mass spectrometry. The kinetic energy distributions of Al through Al[sub 6] were measured by a neutrals time-of-flight technique. The interpretation of laser postionization TOF data to extract velocity and energy distributions is presented. The aluminum cluster distributions are qualitatively similar to previous copper cluster distribution measurements from our laboratory. In contrast to the steep high energy tails predicted by the single- or multiple- collision models, the measured cluster distributions have high energy power law dependences in the range of E[sup [minus]3] to E[sup [minus]4.5]. Correlated collision models may explain the substantial abundance of energetic clusters that are observed in these experiments. Possible influences of cluster fragmentation on the distributions are discussed.

Coon, S.R.; Calaway, W.F.; Pellin, M.J. (Argonne National Lab., IL (United States)); Curlee, G.A. (Trinity Univ., San Antonio, TX (United States). Dept. of Physics); White, J.M. (Texas Univ., Austin, TX (United States). Dept. of Chemistry and Biochemistry)

1992-01-01

351

Kinetic energy distributions of sputtered neutral aluminum clusters: Al--Al{sub 6}  

SciTech Connect

Neutral aluminum clusters sputtered from polycrystalline aluminum were analyzed by laser postionization time-of-flight (TOF) mass spectrometry. The kinetic energy distributions of Al through Al{sub 6} were measured by a neutrals time-of-flight technique. The interpretation of laser postionization TOF data to extract velocity and energy distributions is presented. The aluminum cluster distributions are qualitatively similar to previous copper cluster distribution measurements from our laboratory. In contrast to the steep high energy tails predicted by the single- or multiple- collision models, the measured cluster distributions have high energy power law dependences in the range of E{sup {minus}3} to E{sup {minus}4.5}. Correlated collision models may explain the substantial abundance of energetic clusters that are observed in these experiments. Possible influences of cluster fragmentation on the distributions are discussed.

Coon, S.R.; Calaway, W.F.; Pellin, M.J. [Argonne National Lab., IL (United States); Curlee, G.A. [Trinity Univ., San Antonio, TX (United States). Dept. of Physics; White, J.M. [Texas Univ., Austin, TX (United States). Dept. of Chemistry and Biochemistry

1992-12-01

352

Shock induced reaction of Ni/Al nanopowder mixture.  

PubMed

Nanopowder Ni/Al mixture (mixed in Al:Ni = 2:1 stoichiometry) was shock compressed by employing single and two-stage light gas gun. The particle size of Al and Ni are 100-200 nm and 50-70 nm respectively, morphologies of Al and Ni are sphere like either. Recovered product was characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis. According to the XRD spectrum, the mixed powder undergo complete reaction under shock compression, reaction product consist of Ni2Al3, NiAl and corundum structure Al2O3 compound. Grain size of Ni-Al compound is less than 100 nm. With the shock pressure increasing, the ratio of Ni2Al3 decreased obviously. The corundum crystal size is 400-500 nm according to the SEM observation. The results of shock recovery experiments and analysis show that the threshold pressure for reaction of nano size powder Ni/Al mixture is much less than that of micro size powder. PMID:23421276

Meng, C M; Wei, J J; Chen, Q Y

2012-11-01

353

NMR study of nanophase Al/Al-oxide powder and consolidated composites  

SciTech Connect

{sup 27}Al Nuclear Magnetic Resonance (NMR) measurements from aluminum powders and consolidated nanophase aluminum made from those powders are presented. The signals from the metal and surface oxidation are easily separated and are compared before and after consolidation. The results presented indicate that the oxide coating becomes the interface region within the nanophase composite material and that during consolidation the metal has undergone a deformation equivalent to that seen for bulk material under a compressive strain of between 4% and 8%.

Suits, B.H.; Apte, P.; Wilken, D.E. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Physics; Siegel, R.W. [Argonne National Lab., IL (United States). Materials Science Div.

1994-10-01

354

Lap joint properties of FSWed dissimilar formed 5052 Al and 6061 Al alloys with different thickness  

Microsoft Academic Search

Lap joint friction stir welding (FSW) between dissimilar 5052-H112 (1 mm) and 6061-T6 (2 mm) Al alloys with different thickness\\u000a was carried out with various tool rotation speeds and welding speeds according to the fixed location of each material on bottom\\u000a or top sheet. Interface morphology was characterized by pull-up or pull-down from initial joint line. Amount of vertical material\\u000a transports increased

Chang-Yong Lee; Won-Bae Lee; Jong-Woong Kim; Don-Hyun Choi; Yun-Mo Yeon; Seung-Boo Jung

2008-01-01

355

Al ist das hufigste Metall der Erdkruste Al ist nahezu unlslich whrend der Verwitterung  

E-print Network

lateritischen Gesteinen Aluminium #12;China-Clay #12;Stickstoff Stickstoff (N2) ist das reaktionsträge in Bodenlösung: Phosphat-Anionen schwach basische Wässer Hydrogenphosphat-Anion (HPO4 2-) schwach saure Wässer-Fällung, z.B.: Fe3+ + PO4 3- FePO4 Phosphate als nukleares Endlager? Algenblüte #12;Sauerstoff Wichtigstes

Siebel, Wolfgang

356

Rye oxidative stress under long term Al exposure.  

PubMed

Aluminium (Al) toxicity decreases plant growth. Secale cereale L. is among the most Al-tolerant crop species. In order to study the response to Al-long term exposure, two rye genotypes with different Al sensitivity ('D. Zlote' and 'Riodeva') were exposed to 1.11 and 1.85mM Al and the antioxidant responses were followed for 2 and 3 weeks in roots and leaves. Al toxicity signals, such as a severe decrease in root growth, occurred sooner in 'Riodeva.' The antioxidant response was dependent on the genotype, the organ, Al concentration and the exposure period. Al-exposed roots of 'D. Zlote' showed earlier enhancements of APX, SOD and G-POX activities than those of 'Riodeva.' 'D. Zlote' roots showed stimulation of the AsA-GSH cycle after the second week (when root growth inhibition was less severe), while later (when severe root growth inhibition was observed), oxidation of AsA and GSH pools was observed. In leaves of both genotypes, CAT, SOD and G-POX activities increased with Al exposure. In these leaves, the effect of AsA-GSH was time dependent, with maximum oxidation at the second week, followed by recovery. We confirmed that the oxidation state of AsA and GSH pools is involved in the detoxification of Al-induced oxidative stress. Moreover, our data demonstrate that the production of ROS does not correlate with the Al-induced root growth decrease. Finally, the differences observed over time indicate that long term exposure may provide additional information on rye sensitivity to Al, and contribute to a better understanding of this species' mechanisms of Al tolerance. PMID:23537706

Silva, Sónia; Pinto, Glória; Correia, Barbara; Pinto-Carnide, Olinda; Santos, Conceição

2013-07-01

357

26Al- 26Mg and 207Pb- 206Pb systematics of Allende CAIs: Canonical solar initial 26Al/ 27Al ratio reinstated  

NASA Astrophysics Data System (ADS)

The precise knowledge of the initial 26Al/ 27Al ratio [( 26Al/ 27Al) 0] is crucial if we are to use the very first solid objects formed in our Solar System, calcium-aluminum-rich inclusions (CAIs) as the "time zero" age-anchor and guide future work with other short-lived radio-chronometers in the early Solar System, as well as determining the inventory of heat budgets from radioactivities for early planetary differentiation. New high-precision multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) measurements of 27Al/ 24Mg ratios and Mg-isotopic compositions of nine whole-rock CAIs (six mineralogically characterized fragments and three micro-drilled inclusions) from the CV carbonaceous chondrite, Allende yield a well-defined 26Al- 26Mg fossil isochron with an ( 26Al/ 27Al) 0 of (5.23 ± 0.13) × 10 - 5 . Internal mineral isochrons obtained for three of these CAIs ( A44A, AJEF, and A43) are consistent with the whole-rock CAI isochron. The mineral isochron of AJEF with ( 26Al/ 27Al) 0 = (4.96 ± 0.25) × 10 - 5 , anchored to our precisely determined absolute 207Pb- 206Pb age of 4567.60 ± 0.36 Ma for the same mineral separates, reinstate the "canonical" ( 26Al/ 27Al) 0 of 5 × 10 - 5 for the early Solar System. The uncertainty in ( 26Al/ 27Al) 0 corresponds to a maximum time span of ± 20 Ka (thousand years), suggesting that the Allende CAI formation events were culminated within this time span. Although all Allende CAIs studied experienced multistage formation history, including melting and evaporation in the solar nebula and post-crystallization alteration likely on the asteroidal parent body, the 26Al- 26Mg and U-Pb-isotopic systematics of the mineral separates and bulk CAIs behaved largely as closed-system since their formation. Our data do not support the "supra-canonical" 26Al/ 27Al ratio of individual minerals or their mixtures in CV CAIs, suggesting that the supra-canonical 26Al/ 27Al ratio in the CV CAIs may have resulted from post-crystallization inter-mineral redistribution of Mg isotopes within an individual inclusion. This redistribution must be volumetrically minor in order to satisfy the mass balance of the precisely defined bulk CAI and bulk mineral data obtained by MC-ICP-MS. The radiogenic 208Pb*/ 206Pb* ratio obtained as a by-product from the Pb-Pb age dating is used to estimate time-integrated 232Th/ 238U ratio ( ? value) of CAIs. Limited ? variations among the minerals within a single CAI, contrasted by much larger variations among the bulk CAIs, suggest Th/U fractionation occurred prior to crystallization of igneous CAIs. If interpreted as primordial heterogeneity, the ? value can be used to calculate the mean age of the interstellar dust from which the CAIs condensed.

Jacobsen, Benjamin; Yin, Qing-zhu; Moynier, Frederic; Amelin, Yuri; Krot, Alexander N.; Nagashima, Kazuhide; Hutcheon, Ian D.; Palme, Herbert

2008-07-01

358

3DGRAPE/AL User's Manual  

NASA Technical Reports Server (NTRS)

This document is a users' manual for a new three-dimensional structured multiple-block volume g generator called 3DGRAPE/AL. It is a significantly improved version of the previously-released a widely-distributed programs 3DGRAPE and 3DMAGGS. It generates volume grids by iteratively solving the Poisson Equations in three-dimensions. The right-hand-side terms are designed so that user-specific; grid cell heights and user-specified grid cell skewness near boundary surfaces result automatically, with little user intervention. The code is written in Fortran-77, and can be installed with or without a simple graphical user interface which allows the user to watch as the grid is generated. An introduction describing the improvements over the antecedent 3DGRAPE code is presented first. Then follows a chapter on the basic grid generator program itself, and comments on installing it. The input is then described in detail. After that is a description of the Graphical User Interface. Five example cases are shown next, with plots of the results. Following that is a chapter on two input filters which allow use of input data generated elsewhere. Last is a treatment of the theory embodied in the code.

Sorenson, Reese L.; Alter, Stephen J.

1995-01-01

359

Roll Casting of Al-25%Si  

SciTech Connect

Strip casting of Al-25%Si strip was tried using an unequal diameter twin roll caster. The diameter of the lower roll (large roll) was 1000 mm and the diameter of the upper roll (small roll) was 250 mm. Roll material was mild steel. The sound strip could be cast at the speeds ranging from 8 m/min to 12 m/min. The strip did not stick to the roll without the parting material. The primary Si, which existed at centre area of the thickness direction, was larger than that which existed at other area. The size of the primary Si was smaller than 0.2 mm. Eutectic Si was smaller 5 {mu}m. The as-cast strip was ranging from 2 mm to 3 mm thick and its width was 100 mm. The as-cast strip could be hot rolled down to 1 mm. The hot rolled strip was cold rolled. The primary Si became smaller and the pore occurred around the primary Si after the rolling.

Haga, Toshio [Osaka Institute of Technology, Omiya Asahiku Osaka city 535-8585 (Japan); Harada, Hideto [Graduate School of Osaka Institute of Technology, Omiya Asahiku Osaka city 535-8585 (Japan); Watari, Hisaki [Gunma University, Kiryu city, 376-8515 (Japan)

2011-05-04

360

Urethrocutaneous fistula post-Al-Ghorab shunt  

PubMed Central

Priapism is a rare event that may be induced by clinical conditions and medications. Ischemic priapism (IP) is a compartment syndrome of the penis, and it constitutes a medical emergency that may cause significant morbidity on the erectile function in particular. We report a case of a 30-year-old male in his fourth episode of priapism. The aspiration and washing of the corpora cavernosa with saline solution were performed, followed by washing with adrenaline solution without resolution of the condition. Treatment was followed by the performance of the Al-Ghorab shunt procedure with dorsal incision of the glans. During follow-up, an area of necrosis distal to the incision was detected, and after the catheter removal on postoperative day 14, the patient developed a glandular dorsal urethrocutaneous fistula and meatal stenosis. The meatal stenosis was corrected by Johanson urethroplasty with a neo-meatus at the coronal sulcus, along with resection and debridement of the fistula tract and a three-layer closure.

Paladino, Joao Roberto; Wroclawski, Marcelo; Den Julio, Alexandre; Teixeira, Gabriel Kushyama; Glina, Sidney; Lima Pompeo, Antonio Carlos

2014-01-01

361

ALS liquid hydrogen turbopump: Advanced Development Program  

NASA Technical Reports Server (NTRS)

The point of departure (POD) turbopump concept was reviewed and finalized. The basis for the POD was the configuration presented in the Aerojet proposal. After reviewing this proposal concept, several modifications were made. These modifications include the following: (1) the dual pump discharge arrangement was changed to a single discharge; (2) commonality of the turbine inlet manifold with the advanced launch system (ALS) liquid oxygen (LOX) TPA was dropped for this program; (3) the turbine housing flange arrangement was improved by relocating it away from the first stage nozzles; (4) a ten percent margin (five percent diameter increase) was built into the impeller design to ensure meeting the required discharge pressure without the need for increasing speed; (5) a ten percent turbine power margin was imposed which is to be obtained by increasing turbine inlet pressure if required; and (6) the backup concept, as an alternative to the use of cast impellers, now incorporates forged/machined shrouded impellers, rather than the unshrouded type originally planned.

Shimp, Nancy R.; Claffy, George J.

1989-01-01

362

Oxidative stress biomarkers in sporadic ALS.  

PubMed

We aimed to investigate oxidative stress biomarkers in a cross-sectional pilot study of 50 participants with sporadic ALS (SALS) compared to 46 control subjects. We measured urinary 8-oxodeoxyguanosine (8-oxodG), urinary 15-F(2t)-isoprostane (IsoP), and plasma protein carbonyl by ELISA methods. We also determined if ELISA measurement of 8-oxodG could be validated against measures from high-pressure liquid chromatography coupled with electrochemical detection, the current standard method. We found that 8-oxodG and IsoP levels adjusted for creatinine were significantly elevated in SALS participants. These differences persisted after age and gender were controlled in regression analyses. These markers are highly and positively correlated with each other. 8-oxodG measured by the two techniques from the same urine sample were positively correlated (p<.0001). Protein carbonyl was not different between SALS participants and controls. In conclusion, using ELISA, we confirmed that certain oxidative stress biomarkers were elevated in SALS participants. ELISA may be reliable and thus useful in epidemiology studies requiring large numbers of samples to determine the significance of increased oxidative stress markers in SALS. Further studies are required. PMID:18574762

Mitsumoto, Hiroshi; Santella, Regina M; Liu, Xinhua; Bogdanov, Mikhail; Zipprich, Jennifer; Wu, Hui-Chen; Mahata, Julie; Kilty, Mary; Bednarz, Kate; Bell, Daniel; Gordon, Paul H; Hornig, Mady; Mehrazin, Mahsa; Naini, Ali; Flint Beal, M; Factor-Litvak, Pam

2008-06-01

363

Microstructure and microsegregation in Al-rich Al-Cu-Mg alloys  

SciTech Connect

Microstructure and microsegregation in two directionally solidified Al alloys, Al-3.9Cu-0.9Mg and Al-15Cu-1Mg (in wt%), were investigated for cooling rates between 0.78 and 0.039 K/s. Transverse and longitudinal sections were examined to exhibit dendritic microstructures. Fractions of solids formed were determined using quantitative image analysis and solute redistribution in the primary phase was determined using area scans. The model employed to calculate microsegregation is based on the Scheil model but including solid-state diffusion, dendrite arm coarsening and undercooling of the dendrite tip and the formation of eutectic. The model-calculated results were found to be in good agreement with the experimentally determined concentration distributions in the primary {alpha} phase and the amounts of phases formed. It was found that the dendrite morphology was best described by a cylindrical arm geometry and that the accuracy of the phase diagram could have a significant influence on the microsegregation predictions. For the alloy with low copper content, two types of embedded droplets were observed.

Xie, F.Y.; Kraft, T.; Zuo, Y.; Moon, C.H.; Chang, Y.A. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering] [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering

1999-01-15

364

A study on the subgrain superplasticity of extruded Al-Al{sub 3}Ni eutectic alloy  

SciTech Connect

A directionally solidified Al-Al{sub 3}Ni eutectic alloy was extruded to obtain micron-size subgrains with [111] fiber texture. The extrusion temperature was varied to have different distributions of the Al{sub 3}Ni eutectic particles. Choosing the fiber axis as the loading axis, the tensile test results at 500 C indicate that the elongation is concave downward and strain-rate dependent. Reducing the number of intragranular particles increases the maximum elongation as well as the strain rate of maximum elongation. With the particles residing only intergranularly in the as-extruded state, the maximum elongation, which occurs under the initial strain rate of 6.3 {times} 10{sup {minus}3} s{sup {minus}1}, is about 300 pct. This subgrain superplasticity is associated with low strain-rate sensitivity but high resistance against strain softening. The fiber texture is always retained, and the microstructure reveals slip of long parallel dislocations. If intragranular particles are also present in the as-extruded state, the occurrence of dislocation tangling and dynamic recovery will give rise to early onset of strain softening and inferior ductility.

Uan, J.Y.; Chen, L.H.; Lui, T.S.

1997-02-01

365

Structure of molten Al and eutectic Al-Si alloy studied by neutron diffraction  

SciTech Connect

The structure of molten eutectic Al87.8Si12.2 alloy has been studied by neutron diffraction during a temperature cycle. For comparison measurements were performed on pure molten Al. The measurements show that the alloy after heating above the liquidus contains particles of two kinds, aluminum-rich and silicon-rich. The silicon-rich particles are partly dissolved after a further heating. Earlier published data obtained by the ?-ray absorption technique of the density of the molten eutectic Al–Si alloy had demonstrated the existence of two temperatures above the liquidus temperature: A dissolution temperature Td, at which the microstructure of the melt inherited from the ingot starts to dissolve and a branching temperature, Tb, at which the melt reaches a fully mixed state. The highest temperature that was possible to reach during the neutron experiments lies between Td and Tb. The obtained results support these conclusions that molten alloys after melting are inhomogeneous up to a temperature well above the liquidus. Moreover, the difference in shape between the static structure factors measured by neutron and X-ray diffraction on molten aluminum is observed and is found to be more accentuated and to extend to larger wavevectors than in earlier works.

Dahlborg, U. [University of Rouen; Kramer, Matthew J. [Ames Laboratory; Besser, M. [Ames Laboratory; Morris, J. R. [Oak Ridge National Laboratory; Calvo-Dahlborg, M. [University of Rouen

2012-11-24

366

Role of Al2O3 particulate reinforcements on precipitation in 2014 Al-matrix composites  

NASA Astrophysics Data System (ADS)

Precipitation in commercial aluminum alloy 2014, without and with alumina particulate reinforcements, was studied using microhardness, electrical resistivity, differential scanning calorimetry (DSC), and transmission electron microscopy. The precipitation sequence in 2014 Al was confirmed to be ?ss? ? + GPZ ?? + ?’?a + ?’ + gH?? + ? (AlCuMgSi) + ? (CuAl2). Reinforcement addition decreased the time to peak hardness, but also reduced the peak matrix microhardness. This was traced to a decrease in the amount of ?’ formed in the composites. Further, it was observed that while Guinier-Preston (GP) zone and ?’ formations are accelerated in the composites, ?’ precipitation is decelerated. The acceleration is attributable primarily to enhanced nucleation resulting from an increase in the matrix dislocation density due to coefficient of thermal expansion (CTE) mismatch between the matrix and the reinforcements, whereas the deceleration is associated with a decrease of low-temperature solute diffusivity due to absorption of vacancies at dislocations and interfaces. It was also observed that the degree of overall acceleration in hardening and the reduction in peak matrix microhardness with reinforcement addition decreased with decreasing aging temperatures. The causal relationships of these observations with the associated mechanisms are discussed.

Dutta, I.; Harper, C. P.; Dutta, G.

1994-08-01

367

AlGaN-based ultraviolet light-emitting diodes grown on AlN epilayers  

SciTech Connect

AlGaN-based deep-ultraviolet light-emitting diode (LED) structures, which radiate light at 305 and 290 nm, have been grown on sapphire substrates using an AlN epilayer template. The fabricated devices have a circular geometry to enhance current spreading and light extraction. Circular UV LEDs of different sizes have been characterized. It was found that smaller disk LEDs had higher saturation optical power densities but lower optical powers than the larger devices. This trade-off between power and power density is a result of a compromise between electrical and thermal resistance, as well as the current crowding effect (which is due to the low electrical conductivity of high aluminum composition n- and p-AlGaN layers). Disk UV LEDs should thus have a moderate size to best utilize both total optical power and power density. For 0.85 mmx0.85 mm interdigitated LEDs, a saturation optical power of 2.9 mW (1.8 mW) at 305 nm (290 nm) was also obtained under dc operation.

Kim, K.H.; Fan, Z.Y.; Khizar, M.; Nakarmi, M.L.; Lin, J.Y.; Jiang, H.X. [Department of Physics, Kansas State University, Manhattan, Kansas 66506-2601 (United States)

2004-11-15

368

Stabilization mechanism of ?-Mg17Al12 and ?-Mg2Al3 complex metallic alloys  

NASA Astrophysics Data System (ADS)

Large-unit-cell complex metallic alloys (CMAs) frequently achieve stability by lowering the kinetic energy of the electron system through formation of a pseudogap in the electronic density of states (DOS) across the Fermi energy ?F. By employing experimental techniques that are sensitive to the electronic DOS in the vicinity of ?F, we have studied the stabilization mechanism of two binary CMA phases from the Al-Mg system: the ?-Mg17Al12 phase with 58 atoms in the unit cell and the ?-Mg2Al3 phase with 1178 atoms in the unit cell. Since the investigated alloys are free from transition metal elements, orbital hybridization effects must be small and we were able to test whether the alloys obey the Hume-Rothery stabilization mechanism, where a pseudogap in the DOS is produced by the Fermi surface-Brillouin zone interactions. The results have shown that the DOS of the ?-Mg17Al12 phase exhibits a pronounced pseudogap centered almost exactly at ?F, which is compatible with the theoretical prediction that this phase is stabilized by the Hume-Rothery mechanism. The disordered cubic ?-Mg2Al3 phase is most likely entropically stabilized at high temperatures, whereas at lower temperatures stability is achieved by undergoing a structural phase transition to more ordered rhombohedral ?? phase at 214?° C, where all atomic sites become fully occupied. No pseudogap in the vicinity of ?F was detected for the ?? phase on the energy scale of a few 100 meV as determined by the ‘thermal observation window’ of the Fermi-Dirac function, so that the Hume-Rothery stabilization mechanism is not confirmed for this compound. However, the existence of a much broader shallow pseudogap due to several critical reciprocal lattice vectors \\buildrel{\\rightharpoonup}\\over{G} that simultaneously satisfy the Hume-Rothery interference condition remains the most plausible stabilization mechanism of this phase. At Tc = 0.85 K, the ?? phase undergoes a superconducting transition, which slightly increases the cohesive energy and may contribute to relative stability of this phase against competing neighboring phases.

Vrtnik, S.; Jazbec, S.; Jagodi?, M.; Korelec, A.; Hosnar, L.; Jagli?i?, Z.; Jegli?, P.; Feuerbacher, M.; Mizutani, U.; Dolinšek, J.

2013-10-01

369

Stabilization mechanism of ?-Mg??Al?? and ?-Mg?Al? complex metallic alloys.  

PubMed

Large-unit-cell complex metallic alloys (CMAs) frequently achieve stability by lowering the kinetic energy of the electron system through formation of a pseudogap in the electronic density of states (DOS) across the Fermi energy ?F. By employing experimental techniques that are sensitive to the electronic DOS in the vicinity of ?F, we have studied the stabilization mechanism of two binary CMA phases from the Al-Mg system: the ?-Mg17Al12 phase with 58 atoms in the unit cell and the ?-Mg2Al3 phase with 1178 atoms in the unit cell. Since the investigated alloys are free from transition metal elements, orbital hybridization effects must be small and we were able to test whether the alloys obey the Hume-Rothery stabilization mechanism, where a pseudogap in the DOS is produced by the Fermi surface-Brillouin zone interactions. The results have shown that the DOS of the ?-Mg17Al12 phase exhibits a pronounced pseudogap centered almost exactly at ?F, which is compatible with the theoretical prediction that this phase is stabilized by the Hume-Rothery mechanism. The disordered cubic ?-Mg2Al3 phase is most likely entropically stabilized at high temperatures, whereas at lower temperatures stability is achieved by undergoing a structural phase transition to more ordered rhombohedral ?' phase at 214?° C, where all atomic sites become fully occupied. No pseudogap in the vicinity of ?F was detected for the ?' phase on the energy scale of a few 100 meV as determined by the 'thermal observation window' of the Fermi-Dirac function, so that the Hume-Rothery stabilization mechanism is not confirmed for this compound. However, the existence of a much broader shallow pseudogap due to several critical reciprocal lattice vectors [Formula: see text] that simultaneously satisfy the Hume-Rothery interference condition remains the most plausible stabilization mechanism of this phase. At Tc = 0.85 K, the ?' phase undergoes a superconducting transition, which slightly increases the cohesive energy and may contribute to relative stability of this phase against competing neighboring phases. PMID:24080784

Vrtnik, S; Jazbec, S; Jagodi?, M; Korelec, A; Hosnar, L; Jagli?i?, Z; Jegli?, P; Feuerbacher, M; Mizutani, U; Dolinšek, J

2013-10-23

370

Directional solidification and microstructural control of the TiAl/Ti{sub 3}Al lamellar microstructure in TiAl-Si alloys  

SciTech Connect

Composite microstructures were grown from TiAl-Si alloys with the gamma/alpha2 lamellar microstructure aligned parallel to the growth direction by directional solidification techniques using a seed material. Within the composition range of 40--50 at% Al, the addition of Si to TiAl shifts the primary alpha region towards a much lower Al content. At a composition of Ti-43Al-3Si, either alpha or alpha2 can be stable, from melting temperature to room temperature and the orientation of the lamellar microstructure can be controlled using a seed material. In addition to the gamma/alpha2 lamellae, large Ti{sub 5}Si{sub 3} particles which formed from the liquid, and much smaller Ti{sub 5}Si{sub 3} particles which formed from an eutectoid reaction were observed. The room temperature mechanical properties were determined by tensile and three-point bend tests. From bend specimens oriented with the notch parallel to the lamellar microstructure, the Ti-43Al-3Si alloy was found to have a greater fracture toughness than a TiAl-PST crystal of the same orientation.

Johnson, D.R.; Inui, H.; Yamaguchi, M. [Kyoto Univ. (Japan). Dept. of Materials Science and Engineering] [Kyoto Univ. (Japan). Dept. of Materials Science and Engineering

1996-06-01

371

Corrosion Behaviour of Al Alloys in Sea Water  

SciTech Connect

The electrochemical behaviour of aluminum (Al) alloys in seawater medium was investigated using potentiodynamic technique, complemented by Scanning Electron Microscopy (SEM) and EDAX. SEM was used to characterize the corroded surface and to observe the extent of corrosion attack on the Al alloys after tested in seawater. EDAX analysis was used to identify elements present on the specimen surface. The results indicate that influences of alloying elements present in the Al alloys play important role in the corrosion of Al alloys in seawater. The behaviour of Al alloys with addition of Zn, Sn, Cu and Si was greatly enhanced in terms of its potential and corrosion behaviour. Potential of Al with alloying elements reached value more negative than -0.9 V{sub SCE} and showed active corrosion behaviour.

Kamarudin, S. R. M.; Daud, M.; Muhamad, A.; Sattar, M. S. [Malaysian Nuclear Agency, Bangi, 43000 Kajang (Malaysia); Daud, A. R. [Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600, Bangi (Malaysia)

2010-03-11

372

Reactive codoping of GaAlInP compound semiconductors  

DOEpatents

A GaAlInP compound semiconductor and a method of producing a GaAlInP compound semiconductor are provided. The apparatus and method comprises a GaAs crystal substrate in a metal organic vapor deposition reactor. Al, Ga, In vapors are prepared by thermally decomposing organometallic compounds. P vapors are prepared by thermally decomposing phospine gas, group II vapors are prepared by thermally decomposing an organometallic group IIA or IIB compound. Group VIB vapors are prepared by thermally decomposing a gaseous compound of group VIB. The Al, Ga, In, P, group II, and group VIB vapors grow a GaAlInP crystal doped with group IIA or IIB and group VIB elements on the substrate wherein the group IIA or IIB and a group VIB vapors produced a codoped GaAlInP compound semiconductor with a group IIA or IIB element serving as a p-type dopant having low group II atomic diffusion.

Hanna, Mark Cooper (Boulder, CO); Reedy, Robert (Golden, CO)

2008-02-12

373

X-ray absorption spectroscopy studies on magnetic tunnel junctions with AlO and AlN tunnel barriers  

SciTech Connect

X-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) measurements of the optimized magnetic tunnel junctions (MTJs) with AlO and AlN barriers have been performed to study the chemical structures of the barrier and the underlying layer. These MTJs with AlO and AlN barriers exhibited increased tunneling magnetoresistance (TMR) after annealing at 200 deg. C from 27% to 45% and from 25% to 33%, respectively. Surprisingly, the XPS and XAS measurements confirmed that both the as-grown and the annealed MTJs had metallic Co and Fe at the interface between the barrier and the underlying CoFe layer. After annealing, under-stoichiometric AlO{sub x} and AlN{sub x} phases in MTJs with AlO and AlN barriers partially transformed into stoichiometric Al{sub 2}O{sub 3} and AlN phases, respectively. Thus the increase in TMR after annealing for MTJs with clean interface between the barrier and the underlying layer is believed due to the anion redistribution inside the barrier layer, not from back diffusion from pinned magnetic layer to barrier layer.

Mun, B. S.; Moon, J. C.; Hong, S. W.; Kang, K. S.; Kim, K.; Kim, T. W.; Ju, H. L. [Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States); Department of Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Devices Laboratory, Samsung Advanced Institute of Technology, Giheung, Kyunggi-do 449-711 (Korea, Republic of); Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 and Department of Physics, Yonsei University, Seoul 120-749 (Korea, Republic of)

2006-04-15

374

Characterization of superconducting single-electron transistors with small Al/AlO_{x}/V Josephson junctions  

NASA Astrophysics Data System (ADS)

Superconducting single-electron transistors (SSETs) composed of small Al/AlOx/V junctions were fabricated, and their transport properties were investigated. The device with an Al island exhibited a supercurrent that was 2e-periodic in the gate charge while that with a V island showed a periodicity of e, where e is an elementary charge. The Josephson-quasiparticle (JQP)-cycle current appeared at the bias voltage V in the range {{? }Al}+{{E}c}\\lt e|V|\\lt {{? }Al}+3{{E}c}, where {{? }Al} is the superconducting gap of Al and {{E}c} is the charging energy of an elementary charge. This is different from the commonly accepted range for the JQP current such as that in the case of an all Al SSET. There also appeared a large leakage current at 2{{? }Al}?slant e|V|\\lt 2({{? }V}+{{? }Al}+{{E}c}), where {{? }V} is the superconducting gap of V. All these properties are accounted for by considering the finite subgap quasiparticle density of states in the V electrode.

Shimada, Hiroshi; Miyawaki, Kenji; Hagiwara, Ayano; Takeda, Kouichi; Mizugaki, Yoshinao

2014-11-01

375

Modeling creep deformation of a two-phase TiAl/Ti[sub 3]Al alloy with a lamellar microstructure  

SciTech Connect

A two-phase TiAl/Ti[sub 3]Al alloy with a lamellar microstructure has been previously shown to exhibit a lower minimum creep rate than the minimum creep rates of the constituent TiAl and Ti[sub 3]Al single-phase alloys. Fiducial-line experiments described in the present article demonstrate that the creep rates of the constituent phases within the two-phase TiAl/Ti[sub 3]Al lamellar alloy tested in compression are more than an order of magnitude lower than the creep rates of single-phase TiAl and Ti[sub 3]Al alloys tested in compression at the same stress and temperature. Additionally, the fiducial-line experiments show that no interfacial sliding of the phases in the TiAl/Ti[sub 3]Al lamellar alloy occurs during creep. The lower creep rate of the lamellar alloy is attributed to enhanced hardening of the constituent phases within the lamellar microstructure. A composite-strength model has been formulated to predict the creep rate of the lamellar alloy, taking into account the lower creep rates of the constituent phases within the lamellar microstructure. Application of the model yields a very good correlation between the predicted an experimentally observed minimum creep rates over moderate stress and temperature ranges.

Bartholomeusz, M.F. (Reynolds Metal Co., Richmond, VA (United States)); Wert, J.A. (Univ. of Virginia, Charlottesville, VA (United States). Dept. of Materials Science and Engineering)

1994-10-01

376

Influence of Mixing Technique on the Mechanical Properties and Structural Evolution of Al-NiAl Composites  

NASA Astrophysics Data System (ADS)

Fabrication and processing of 99.7% purity aluminum powder reinforced with 0, 5, 10% volume fractions NiAl intermetallic metal matrix composites were conducted. The mechanically alloyed nanostructured NiAl was mixed by both regular and high energy ball milling techniques. Powders of NiAl employed for reinforcement were milled for 18 and 31 h, and therefore denoted as NiAl18 and NiAl31, respectively. The mixed powders were consolidated via a combination of cold pressing followed by hot extrusion at 480 °C for 1 h at a reduction ratio 4:1. Hardness, tensile properties, and fracture behavior of the extruded composite powders were evaluated. Structural evolution of the milled composite powders was investigated before and after extrusion using optical microscopy, field emission scanning, and transmission electron microscopy. In addition, particle type identification was carried out via energy dispersive x-ray analysis. Introducing NiAl31 (0.8 µm) enhanced the mechanical properties of the composites compared to NiAl18 (1.0 µm). Moreover, powders milling enhanced the tensile properties post hot extrusion compared to the mixed conditions due to the enhanced reinforcement distribution and bonding with the Al matrices. Hot extruded milled composite powders of Al reinforced with 10% NiAl31 produced nanostructured high-angle grain boundary structure <200 nm.

Abd Elhamid, M.; Emara, Mohamed M.; Salem, Hanadi G.

2014-10-01

377

A Monoclonal Antibody Specific for Candida albicans Als4 Demonstrates Overlapping Localization of Als Family Proteins on the Fungal Cell Surface and Highlights Differences between Als Localization in vitro and in vivo  

PubMed Central

The Candida albicans ALS (agglutinin-like sequence) family encodes large cell-surface glycoproteins that function in adhesion of the fungus to host and abiotic surfaces. Monoclonal antibodies (mAbs) specific for each Als protein were developed to study Als localization on the C. albicans surface. An anti-Als4 mAb demonstrated that Als4 covers the surface of yeast cells, with a greater abundance of Als4 on cells grown at 30°C compared to 37°C. On germ tubes, Als4 is localized in a restricted area proximal to the mother yeast. Immunolabeling with several anti-Als mAbs showed overlapping localization of Als1 and Als4 on yeast cells and Als1, Als3 and Als4 on germ tubes. Overlapping localization of Als proteins was also observed on yeast and hyphae recovered from mouse models of disseminated and oral candidiasis. Differences between Als localization in vivo and in vitro suggested changes in regulation of Als production in the host compared to the culture flask. Characterization with the anti-Als mAbs reveals the simultaneous presence and differences in relative abundance of Als proteins, creating an accurate image of Als representation and localization that can be used to guide conclusions regarding individual and collective Als protein function. PMID:22106872

Coleman, David A.; Oh, Soon-Hwan; Manfra-Maretta, Sandra L.; Hoyer, Lois L.

2011-01-01

378

Supporting Information Bai et al. 10.1073/pnas.1215713109  

E-print Network

Supporting Information Bai et al. 10.1073/pnas.1215713109 SI Text The frequency-dependent fall(5):1028­1046. Bai et al. www.pnas.org/cgi/content/short/1215713109 1 of 8 #12;Fig. S1. caDNAno object design diagram. Scaffold strand path is depicted with black lines, and staple strands are shown as red lines. Bai et al

Dietz, Hendrik

379

Phase stability of AlYB14 sputtered thin films  

Microsoft Academic Search

AlYB14 (Imma) thin films were synthesized by magnetron sputtering. On the basis of x-ray diffraction, no phases other than crystalline AlYB14 could be identified. According to electron probe microanalysis, energy dispersive x-ray analysis and elastic recoil detection analysis, the Al and Y occupancies vary in the range of 0.73-1.0 and 0.29-0.45, respectively. Density functional theory based calculations were carried out

Helmut Kölpin; Graeme Henkelman; Jens Emmerlich; Frans Munnik; Jochen M. Schneider

2009-01-01

380

Radiation Hard AlGaN Detectors and Imager  

SciTech Connect

Radiation hardness of AlGaN photodiodes was tested using a 65 MeV proton beam with a total proton fluence of 3x10{sup 12} protons/cm{sup 2}. AlGaN Deep UV Photodiode have extremely high radiation hardness. These new devices have mission critical applications in high energy density physics (HEDP) and space explorations. These new devices satisfy radiation hardness requirements by NIF. NSTec is developing next generation AlGaN optoelectronics and imagers.

None

2012-05-01

381

Nonsymmetric AlGaN directional coupler switch analysis  

Microsoft Academic Search

AlGaN has been in the spotlight lately for its use in blue to UV lasers and LEDs, tolerances to high temperature\\/harsh environment, high power applications, etc. Little has been examined in the area of electro-optic (EO) modulation and waveguiding. This paper compiles the optical and EO properties of AlGaN. It also models the behavior of AlGaN integrated optic waveguides and

Antonio Crespo; Mohammad A. Karim

1998-01-01

382

Al-Qaeda's Operational Evolution: Behavioral and Organizational Perspectives  

Microsoft Academic Search

Al-Qaeda is widely regarded by the military, law enforce- ment, diplomatic, and intelligence communities as being the foremost threat to U.S. national security and safety. The nature of this threat, however, has changed since al- Qaeda first emerged in the late 1980s. This article de- scribes the emergence of a new form of transnational terrorism and details al-Qaeda's progression from

Randy Borum; Michael Gelles

2005-01-01

383

Formation and characterization of OH–Al–humate–montmorillonite complexes  

Microsoft Academic Search

We studied the formation of OH–Al–humate–montmorillonite complexes as affected by the nature of the humic acid and the sequence of addition of montmorillonite, humic acid and hydrolytic species of Al. Complexes were prepared at pH 7.0 by different addition sequences of montmorillonite, 3 or 6 mmol Al and 5, 10 or 20 mg of humic acid per g of clay.

A Violante; M Arienzo; F Sannino; C Colombo; A Piccolo; L Gianfreda

1999-01-01

384

Understanding fracture toughness in gamma TiAl  

NASA Astrophysics Data System (ADS)

The ambient-temperature ductility and fracture toughness of TiAl-base intermetallic alloys have been improved in recent years by both alloy additions and microstructural control. Two-phase TiAl alloys have emerged as a new class of lightweight, high-temperature materials with potential importance for aerospace applications. This overview summarizes recent advances in the basic understanding of the fracture processes and toughening mechanisms in TiAl-base alloys and the relationships between microstructures and mechanical properties.

Chan, Kwai S.

1992-05-01

385

Crystallization Behaviour of Amorphous Al-Ni-Nd Alloy  

SciTech Connect

In this study, crystallization behaviour of rapidly solidified Al85Ni5Nd10 alloy has been investigated by differential scanning calorimetry (DSC). Continuous heating DSC trace of amorphous Al85Ni5Nd10 alloy consisted of three exothermic peaks. This indicated that; crystallization of amorphous Al85Ni5Nd10 alloy during continous heating takes places in three stages. Before the first exothermic peak, a glass transition temperature was observed.

Goegebakan, Musa; Guendes, Alaaddin [Department of Physics, Faculty of Art and Science, Kahramanmaras Sutcu Imam University, Kahramanmaras, 46000 (Turkey)

2007-04-23

386

The cyclic oxidation resistance at 1200 C of beta-NiAl, FeAl, and CoAl alloys with selected third element additions  

NASA Technical Reports Server (NTRS)

The intermetallic compounds Beta-NiAl, FeAl, and CoAl were tested in cyclic oxidation with selected third element alloy additions. Tests in static air for 200 1-hr cycles at 1200 C indicated by specific weight change/time data and x-ray diffraction analysis that the 5 at percent alloy additions did not significantly improve the oxidation resistance over the alumina forming baseline alloys without the additions. Many of the alloy additions were actually deleterious. Ta and Nb were the only alloy additions that actually altered the nature of the oxide(s) formed and still maintained the oxidation resistance of the protective alumina scale.

Barrett, C. A.; Titran, R. H.

1992-01-01

387

Rapamycin increases survival in ALS mice lacking mature lymphocytes  

PubMed Central

Background Amyotrophic Lateral Sclerosis (ALS) is a devastating progressive neurodegenerative disease. Disease pathophysiology is complex and not yet fully understood, but is proposed to include the accumulation of misfolded proteins, as aggregates are present in spinal cords from ALS patients and in ALS model organisms. Increasing autophagy is hypothesized to be protective in ALS as it removes these aggregates. Rapamycin is frequently used to increase autophagy, but is also a potent immune suppressor. To properly assess the role of rapamycin-induced autophagy, the immune suppressive role of rapamycin should be negated. Findings Autophagy is increased in the spinal cord of ALS mice. Dietary supplementation of rapamycin increases autophagy, but does not increase the survival of mutant SOD1 mice. To measure the effect of rapamycin in ALS independent of immunosuppression, we tested the effect of rapamycin in ALS mice deficient of mature lymphocytes. Our results show that rapamycin moderately increases the survival of these ALS mice deficient of mature lymphocytes. Conclusions Rapamycin could suppress protective immune responses while enhancing protective autophagy reactions during the ALS disease process. While these opposing effects can cancel each other out, the use of immunodeficient mice allows segregation of effects. Our results indicate that maximal therapeutic benefit may be achieved through the use of compounds that enhance autophagy without causing immune suppression. PMID:24025516

2013-01-01

388

Completion of the Brightness Upgrade of the ALS  

NASA Astrophysics Data System (ADS)

The Advanced Light Source (ALS) at Berkeley Lab remains one of the brightest sources for soft x-rays worldwide. A multiyear upgrade of the ALS is underway, which includes new and replacement x-ray beamlines, a replacement of many of the original insertion devices and many upgrades to the accelerator. The accelerator upgrade that affects the ALS performance most directly is the ALS brightness upgrade [1], which reduces the horizontal emittance from 6.3 to 2.0 nm (2.5 nm effective). Magnets for this upgrade were installed in late 2012 and early 2013 followed by user operation with the reduced emittance.

Steier, C.; Madur, A.; Bailey, B.; Berg, K.; Biocca, A.; Black, A.; Casey, P.; Colomb, D.; Gunion, B.; Li, N.; Marks, S.; Nishimura, H.; Pappas, C.; Petermann, K.; Portmann, G.; Prestemon, S.; Rawlins, A.; Robin, D.; Rossi, S.; Scarvie, T.; Schlueter, R.; Sun, C.; Tarawneh, H.; Wan, W.; Williams, E.; Yin, L.; Zhou, Q.; Jin, J.; Zhang, J.; Chen, C.; Wen, Y.; Wu, J.

2014-03-01

389

Homenaje nacional al maestro Carballido: Setenta años de Carballido  

E-print Network

, comenzó el homenaje al Carballido dramaturgo con una ceremonia en Xalapa, donde se celebraron los 25 años de Tramoya, la revista de teatro que Carballido fundó y que sigue dirigiendo hoy en día. Después, se presentaron en la Ciudad de México dos mesas... Carballido fuera de México y de sus muchos aportes al teatro mexicano tanto como al teatro mundial. Al día siguiente, los mismos participantes se trasladaron a Querétaro, adonde fueron invitados por el Estado de Querétaro y el Consejo Estatal para la...

Bixler, Jacqueline Eyring

1995-10-01

390

Properties of TiAlON/spinel ceramic composites  

SciTech Connect

The U.S. Bureau of Mines is investigating composites in the system TiN/Al{sub 2}O{sub 3}/AlN as potential substitutes for critical and strategic materials. Electrical and physical property data, including oxidation resistance, hardness, strength, and fracture toughness of a titanium-aluminum-oxynitride (TiAlON) aluminum oxynitride spinel composite are presented. The relationship between material properties, composition, phases, and processing parameters is discussed. The effects of additives such as yttria, lanthana, and ceria are also presented. TiAlON/spinel composites exhibit variable strength and electrical resistivity dependent on composition. 7 refs.

Hoyer, J.L.; Bennett, J.P.; Liles, K.J.

1990-10-01

391

Enhanced dehalogenation of halogenated methanes by bimetallic Cu/Al.  

PubMed

A low-cost and high effective copper/aluminum (Cu/Al) bimetal has been developed for treatments of halogenated methanes, including dichloromethane, in near neutral and high pH aqueous systems. Bimetallic Cu/Al was prepared by a simple two-step synthetic method where Cu was deposited onto the Al surface. The presence of Cu on Al significantly enhanced rates of degradation of halogenated methanes and reduced toxic halogenated intermediates. The stability of Cu/Al was preliminarily studied by a multi-spiking batch experiment where complete degradation of carbon tetrachloride was achieved for seven times although the Cu/Al aging was found. Roles of Cu may involve protecting Al against an undesirable oxidation with water, enhancing reaction rates through the galvanic corrosion, and increasing the selectivity to a benign compound (i.e., methane). Kinetic analyses indicated that the activity of bimetallic Cu/Al was comparable to that of iron-based bimetals (e.g., palladized iron) and zero-valent metals. Bimetallic Cu/Al could be a promising reactive reagent for remediation of halogenated solvents-contaminated groundwater associated with high pH problems. PMID:12365834

Lien, Hsing-Lung; Zhang, Weixian

2002-10-01

392

Das Elektrofahrzeug als flexibler Verbraucher und Energiespeicher im Smart Home.  

E-print Network

??Die vorliegende Arbeit beschäftigt sich mit der Integration eines rückspeisefähigen Elektrofahrzeugs in das Energiemanagement-System eines Smart Home. Ziel ist es, das Elektrofahrzeug bestmöglich als flexibel… (more)

Mültin, Marc

2014-01-01

393

Fatigue crack growth behaviour of Al-Li alloys  

NASA Astrophysics Data System (ADS)

Al-Li alloys are being used in aircraft structures due to its low density and inherent mechanical properties. Fatigue Crack Growth (FCG) resistance is usually high compared to conventional Al-alloys attributed to increased modulus and crack closure. Extensive investigations concern about the FCG resistance and crack closure in Al-Li alloys. The present work reviews the FCG resistance in Al-Li alloys and the mechanisms associated with it. The alloy 8090 is taken for the consideration and sometimes compared with 2024.

Saravanakumar, R.; Ramakrishna, K. S.; Kanna, B. Avinash

2013-06-01

394

al-Qaida Strategy, Ideology, Doctrine, and Media  

ScienceCinema

Dr. Jarret Brachman, an internationally recognized al-Qaida specialist, author and public lecturer, shares his thoughts on a range of topics, including the differences involved in fighting insurgent groups versus terrorist organizations, the future of the global al-Qaida movement, and assessing America's efforts to combat al-Qaida. In his talk, Brachman focuses specifically on current trends in al-Qaida's military and messaging strategies, both from the perspective of the group's senior leadership and its regional commands. Presented on June 17, 2010.

Dr. Jarret Brachman

2010-09-01

395

al-Qaida Strategy, Ideology, Doctrine, and Media  

SciTech Connect

Dr. Jarret Brachman, an internationally recognized al-Qaida specialist, author and public lecturer, shares his thoughts on a range of topics, including the differences involved in fighting insurgent groups versus terrorist organizations, the future of the global al-Qaida movement, and assessing America's efforts to combat al-Qaida. In his talk, Brachman focuses specifically on current trends in al-Qaida's military and messaging strategies, both from the perspective of the group's senior leadership and its regional commands. Presented on June 17, 2010.

Dr. Jarret Brachman

2010-06-29

396

Interdiffusion and Intrinsic Diffusion in the Mg-Al System  

SciTech Connect

Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96%) and Al (99.999%). Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopes were utilized to identify the formation of the intermetallic phases, -Al12Mg17 and -Al3Mg2 and absence of the -phase in the diffusion couples. Thicknesses of the -Al12Mg17 and -Al3Mg2 phases were measured and the parabolic growth constants were calculated to determine the activation energies for the growth, 165 and 86 KJ/mole, respectively. Concentration profiles were determined with electron microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, -Al12Mg17 and - Al3Mg2 and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the -Al3Mg2 phase, followed by -Al12Mg17, Al-solid solution and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann s analysis (e.g., marker plane) were determined for the ~38 at.% Mg in the -Al3Mg2 phase. Activation energies and the pre-exponential factors for the inter- and intrinsic diffusion coefficients were calculated for the temperature range examined. The -Al3Mg2 phase was found to have the lowest activation energies for growth and interdiffusion among all four phases studied. At the marker location in the -Al3Mg2 phase, the intrinsic diffusion of Al was found to be faster than that of Mg. Extrapolations of the impurity diffusion coefficients in the terminal solid solutions were made and compared to the available self- and impurity diffusion data from literature. Thermodynamic factor, tracer diffusion coefficients and atomic mobilities at the marker plane composition were approximated using available literature values of Mg activity in the -Al3Mg2 phase.

Brennan, Sarah [University of Central Florida; Bermudez, Katrina [University of Central Florida; Sohn, Yong Ho [University of Central Florida; Kulkarni, Nagraj S [ORNL

2012-01-01

397

Iron Metabolism Disturbance in a French Cohort of ALS Patients  

PubMed Central

Objective. The aim of this study was to assess iron status in a cohort of amyotrophic lateral sclerosis (ALS) patients compared to controls in order to evaluate these parameters as a risk factor or a modifying factor of ALS. Methods. We collected serum iron, ferritin, transferrin, total iron-binding capacity, and transferrin saturation coefficient (TSC) from 104 ALS patients at the time of diagnosis and from 145 controls. We reported phenotypic characteristics and evolution parameters such as ALSFRS-R and forced vital capacity at diagnosis and after one year of follow-up. In a first step we compared iron status between ALS patients and controls, and then we evaluated the relation between iron status and disease evolution of ALS patients using univariate and multivariate analysis. Results. We observed increased concentrations of serum iron (P = 0.002) and ferritin (P < 0.0001) and increased TSC (P = 0.017) in ALS patients. We also showed an association between markers of iron status and high body weight loss in ALS patients. The multivariate analysis of survival highlighted a significant relation between ferritin level and disease duration (P = 0.038). Conclusion. This is the first study showing a higher concentration of serum iron in ALS patients, strengthening the involvement of a deregulation of iron metabolism in ALS. PMID:25101285

Corcia, Philippe; Mucha, Aleksandra; Benzimra, Simon; Mallet, Cindy; Gendrot, Chantal; Moreau, Caroline; Devos, David; Piver, Eric; Pages, Jean-Christophe; Maillot, Francois; Andres, Christian R.; Vourc'h, Patrick; Blasco, Helene

2014-01-01

398

Al-Cr-Fe (Aluminum-Chromium-Iron)  

SciTech Connect

[88Ray] reviewed the experimental data on this system and presented the reviewed results as: (1) a liquidus projection for alloys near the Al-corner; (2) liquidus and solidus projections for the other regions; (3) isothermal sections for alloys with less than 50 wt.% Al at 1150, 900, 750, 700, 650, and 600{degrees}C; (4) an isothermal section at 600{degrees}C near the Al-corner; (5) a partial reaction sequence; and (6) vertical sections depicting the ordering reactions in Fe{sub 3}Al as a function of Cr content.

Raghavan, V.

1994-08-01

399

Diamond/AlN Thin Films for Optical Applications  

SciTech Connect

In this work we report on membranes made of nanocrystalline diamond (NCD) and AlN for the use in tunable micro-optics. For the growth of the AlN and NCD thin films, magnetron sputtering and chemical vapor deposition techniques have been used, respectively. A chemical-mechanical polishing process of NCD layers has been introduced, which is crucial for the growth of c-oriented, fiber textured AlN films. AlN layers deposited on as grown and polished nanocrystalline diamond along with free standing membranes have been compared by studying microstructure, surface morphology, piezoelectrical response as well as optical properties.

Knoebber, F.; Bludau, O.; Williams, O. A.; Sah, R. E.; Kirste, L.; Baeumler, M.; Nebel, C. E.; Ambacher, O.; Cimalla, V.; Lebedev, V. [Fraunhofer Institute for Applied Solid State Physics, Tullastr. 72, 79108 Freiburg (Germany); Leopold, S.; Paetz, D. [IMN MacroNano registered , Ilmenau University of Technology, PF 100565, 98684 Ilmenau (Germany)

2010-11-01

400

Planarization of B7- and B12- clusters by isoelectronic substitution: AlB6- and AlB11-.  

PubMed

Small boron clusters have been shown to be planar from a series of combined photoelectron spectroscopy and theoretical studies. However, a number of boron clusters are quasiplanar, such as B(7)(-) and B(12)(-). To elucidate the nature of the nonplanarity in these clusters, we have investigated the electronic structure and chemical bonding of two isoelectronic Al-doped boron clusters, AlB(6)(-) and AlB(11)(-). Vibrationally resolved photoelectron spectra were obtained for AlB(6)(-), resulting in an accurate electron affinity (EA) for AlB(6) of 2.49 ± 0.03 eV. The photoelectron spectra of AlB(11)(-) revealed the presence of two isomers with EAs of 2.16 ± 0.03 and 2.33 ± 0.03 eV, respectively. Global minimum structures of both AlB(6)(-) and AlB(11)(-) were established from unbiased searches and comparison with the experimental data. The global minimum of AlB(6)(-) is nearly planar with a central B atom and an AlB(5) six membered ring, in contrast to that of B(7)(-), which possesses a C(2v) structure with a large distortion from planarity. Two nearly degenerate structures were found for AlB(11)(-) competing for the global minimum, in agreement with the experimental observation. One of these isomers with the lower EA can be viewed as substituting a peripheral B atom by Al in B(12)(-), which has a bowl shape with a B(9) outer ring and an out-of-plane inner B(3) triangle. The second isomer of AlB(11)(-) can be viewed as an Al atom interacting with a B(11)(-) cluster. Both isomers of AlB(11)(-) are perfectly planar. It is shown that Al substitution of a peripheral B atom in B(7)(-) and B(12)(-) induces planarization by slightly expanding the outer ring due to the larger size of Al. PMID:21520972

Romanescu, Constantin; Sergeeva, Alina P; Li, Wei-Li; Boldyrev, Alexander I; Wang, Lai-Sheng

2011-06-01

401

TEM (transmission electron microscopy) studies of oxidized NiAl and Ni sub 3 Al cross sections  

SciTech Connect

Cross sections of oxide scale/(Ni-Al) intermetallics were prepared by a new method and studied using primarily transmission electron microscopy (TEM). The cross sections were prepared by encasing an oxidized metal specimen sandwich in a low-melting-temperature zinc alloy. Observations of oxidized zirconium-doped {beta}-NiAl cross sections revealed crystallographic voids beneath an adherent Al{sub 2}O{sub 3} scale. The oxide-metal interface was incoherent, but a high dislocation density in the metal near the interface suggested that a large tensile stress was induced by the attached oxide scale. A duplex Al{sub 2}O-NiAl{sub 2}o{sub 4} scale formed on zirconium-doped and zirconium/boron-doped {gamma}{prime}-Ni{sub 3}Al alloys. Additional results are presented involving oxidation mechanisms and oxide-metal interface structures.

Doychak, J.; Ruehle, M. (Max-Planck-Institute fuer Metallforschung, Stuttgart (West Germany))

1989-06-01

402

27Al multiple-quantum MAS NMR of mechanically treated bayerite (alpha-Al(OH)3) and silica mixtures.  

PubMed

Two-dimensional 27Al multiple-quantum magic angle spinning (MQMAS) NMR experiments are used to study mixtures of bayerite (alpha-Al(OH)3) with either silicic acid (SiO2.nH2O) or silica gel (SiO2) that have been ground together for varying lengths of time. This mechanical treatment produces changes in the 27Al MAS and MQMAS NMR spectra that correspond to the formation of new Al species. Mean values of the quadrupolar interaction (PQ) and isotropic chemical shift (deltacs) are extracted from the two-dimensional 27Al NMR spectra for each of these species. The presence of significant distributions of both 27Al quadrupolar and chemical shift parameters is demonstrated and the effect of grinding duration on the magnitudes of these distributions is discussed. PMID:11846239

Ashbrook, S E; MacKenzie, K J; Wimperis, S

2001-01-01

403

HRTEM image contrast and atomistic microstructures of long-period ordered Al-rich TiAl alloys.  

PubMed

Long-period superstructures formed in off-stoichiometric L 1(0)-TiAl alloys were investigated by high-resolution transmission electron microscopy (HRTEM). The HRTEM analysis combined with multislice simulation and image processing was carried out to clarify atomistic microstructures of Al5Ti3 and h-Al2Ti ordered states and a short-range ordered (SRO) state in Ti-62.5 at.% Al alloys. Aluminium atoms in the (002) Ti layers form square-, lean rhombus- and fat rhombus-type ordered clusters in the SRO state. The ordered clusters are in contact with each other and form microdomains of various long-period superstructures. The ordered clusters are tiled periodically in a long range to form Al5Ti3 or h-Al2Ti domains and characteristic antiphase boundary structures. PMID:15077893

Hata, Satoshi; Higuchi, Kiyoshi; Mitate, Toshitsugu; Itakura, Masaru; Tomokiyo, Yoshitsugu; Kuwano, Noriyuki; Nakano, Takayoshi; Nagasawa, Yosuke; Umakoshi, Yukichi

2004-01-01

404

Surface anisotropy in optical second harmonic generation II. Embedding approach to Al(111) and vicinal Al(001) surfaces  

NASA Astrophysics Data System (ADS)

The anisotropic nonlinear optical response of Al(111) and vicinal Al(001) surfaces is calculated microscopically with the aim of analyzing second harmonic generation measurements on these systems. The electronic states and currents are evaluated within the embedding approach which provides a more accurate description than the two-band model for Al slabs used previously by Petukhov and Liebsch. Although we find appreciable differences in detail, the qualitative picture derived from these calculations is confirmed. In particular, we verify that the anisotropic current giving rise to the Xxxx( ?) component of the nonlinear surface polarizability exhibits a remarkably large penetration depth and a strong frequency dependence close to the main interband transitions of Al. For Al(111) as well as vicinal Al surfaces, the physical origin of the anisotropy is the nonsymmetric stacking of the lattice planes parallel to the macroscopic surface rather than the corrugation of the outer electronic density profile.

Ishida, H.; Petukhov, A. V.; Liebsch, A.

1995-10-01

405

Signature of Al11Sm3 fragments in undercooled Al90Sm10 liquid from ab initio molecular dynamics simulations.  

PubMed

An ab initio molecular dynamics (MD) simulation is performed to investigate the structural evolution in Al(90)Sm(10) liquid from 1500 to 900 K. Development of Al(11)Sm(3) local order upon rapid cooling is suggested by the Honeycutt-Anderson (HA) index analysis and the appearance of a predominant Sm-Sm-Sm bond angle around 90° when the liquid approaches the melting point (?920 K). Direct structural evidence of Al(11)Sm(3) fragments at 900 K is obtained using an atomic cluster alignment method developed recently. Meanwhile, development of strong icosahedral short range order (ISRO) and a non-negligible amount of fcc-type clusters around Al in the system are also observed. These results suggest that fcc Al and Al(11)Sm(3) crystalline phases would compete strongly with the formation of an amorphous phase that exhibits ISRO in the diffusionless solidification limit upon rapid quenching. PMID:21613690

Fang, X W; Wang, C Z; Yao, Y X; Ding, Z J; Ho, K M

2011-06-15

406

Signature of Al11Sm3 fragments in undercooled Al90Sm10 liquid from ab initio molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

An ab initio molecular dynamics (MD) simulation is performed to investigate the structural evolution in Al90Sm10 liquid from 1500 to 900 K. Development of Al11Sm3 local order upon rapid cooling is suggested by the Honeycutt-Anderson (HA) index analysis and the appearance of a predominant Sm-Sm-Sm bond angle around 90° when the liquid approaches the melting point (~920 K). Direct structural evidence of Al11Sm3 fragments at 900 K is obtained using an atomic cluster alignment method developed recently. Meanwhile, development of strong icosahedral short range order (ISRO) and a non-negligible amount of fcc-type clusters around Al in the system are also observed. These results suggest that fcc Al and Al11Sm3 crystalline phases would compete strongly with the formation of an amorphous phase that exhibits ISRO in the diffusionless solidification limit upon rapid quenching.

Fang, X. W.; Wang, C. Z.; Yao, Y. X.; Ding, Z. J.; Ho, K. M.

2011-06-01

407

Analysis of transconductance characteristic of AlGaN/GaN HEMTs with graded AlGaN layer  

NASA Astrophysics Data System (ADS)

A theoretical study of transconductance characteristics (gm - Vgs profile) of AlGaN/GaN high electron mobility transistors (HEMTs) with a graded AlGaN layer is given in this paper. The calculations were made using a self-consistent solution of the Schrödinger-Poisson equations and an AlGaN/GaN HEMTs numerical device model. Transconductance characteristics of the devices are discussed while the thickness and Al composition of the graded AlGaN layer are optimized. It is found that graded AlGaN layer structure can tailor device's gm - Vgs profile by improving polar optical phonon mobility and interface roughness mobility. Good agreement is obtained between the theoretical calculations and experimental measurements over the full range of applied gate bias.

Qu, Shenqi; Wang, Xiaoliang; Xiao, Hongling; Wang, Cuimei; Jiang, Lijuan; Feng, Chun; Chen, Hong; Yin, Haibo; Peng, Enchao; Kang, He; Wang, Zhanguo; Hou, Xun

2014-05-01

408

Lithium-ion conduction in complex hydrides LiAlH4 and Li3AlH6  

NASA Astrophysics Data System (ADS)

Lithium-ion conduction in complex hydrides LiAlH4 and Li3AlH6 was investigated using ac complex impedance measurements. The conductivities at room temperature were 8.7×10-9 S/cm in the case of LiAlH4 and 1.4×10-7 S/cm in the case of Li3AlH6. To enhance the conductivity of Li3AlH6 having good thermal stability in heating/cooling cycles, mechanical milling, and addition of lithium halides (LiCl, LiI) were implemented. The maximum value of 2.5×10-4 S/cm at 393 K was observed when 0.33 M ratio of LiI was added to Li3AlH6. This study demonstrated two research directions to enhance the lithium-ion conductivity in a variety of complex hydrides.

Oguchi, H.; Matsuo, M.; Sato, T.; Takamura, H.; Maekawa, H.; Kuwano, H.; Orimo, S.

2010-05-01

409

Efficient synthesis of ferrocenylenones by Friedel–Crafts acylation with EtAlCl 2–Me 3Al  

Microsoft Academic Search

Efficient synthesis of ferrocenylenones using a Friedel–Crafts acylation reaction is described. Acryloyl, methacryloyl, crotonoyl, cinnamoyl, and ?-methylcrotonoyl chlorides react with ferrocene in the presence of a Lewis acid (EtAlCl2 or EtAlCl2–Me3Al) to give the corresponding ferrocenylenones (acryloyl, methacryloyl, crotonoyl, cinnamoyl, and methylcrotonoylferrocenes) in good isolated yields. Besides ferrocenylenones, chloroactylferrocene is also synthesised by this method.

Özdemir Dogan; Volkan ?enol; Serhat Zeytinci; Hasan Koyuncu; Adnan Bulut

2005-01-01

410

Corrosion protection of ion vapor deposition (IVD) Al-coated Al alloys by low-temperature plasma interface engineering  

Microsoft Academic Search

Anode magnetron enhanced DC cathodic plasmas were used to treat ion vapor deposition (IVD) aluminum-coated 2024-T3 and 7075-T6 Al alloys for the creation of plasma interface-engineered systems of IVD\\/plasma polymer\\/primer. Cathodic electrocoat (E-coat) and three kinds of spray paints were employed as primers. Plasma treatment and polymerization on IVD Al-coated Al alloys provided an excellent adhesion base for succeeding primer

Qingsong Yu; Joan Deffeyes; Hirotsugu Yasuda

2001-01-01

411

Recent results on AlN growth by HVPE and fabrication of free standing AlN wafers  

Microsoft Academic Search

Properties of thick crack-free AlN layers grown by hydride vapor phase epitaxy (HVPE) on 2-inch and 3-inch silicon carbide (SiC) and sapphire substrates are described. The maximum thickness of crack free layer was 75 m and 15 m for AlN grown on SiC and sapphire, respectively. Wafer bow was contolled below 50 m for AlN\\/SiC wafers. Surface for as-grown and

V. Soukhoveev; O. Kovalenkov; V. Ivantsov; A. Syrkin; A. Usikov; V. Maslennikov; V. Dmitriev

2006-01-01

412

The site occupancies of alloying elements in TiAl and Ti{sub 3}Al alloys  

SciTech Connect

The site occupancies of V, Cr, Mn, Fe, Ni, Zr, Nb, Mo, Ta, Ga and Sn (1--5 at.%) in TiAl alloys with different compositions, and in Ti{sub 3}Al with the compositions of Ti-26 at.%Al-(1--2 at.%)X, were measured by the atom location channeling enhanced microanalysis (ALCHEMI) method. For TiAl alloys, the results show that Zr, Nb and Ta atoms invariably occupy Ti sites, while Fe, Ni, Ga and Sn atoms occupy Al sites, the alloy composition having no significant influence on their site preference. By contrast, the site preference of V, Cr, and Mn changes considerably with alloy composition (the Ti/Al ratio in particular), the probability of these elements substituting for Ti decreasing in the above order. For quaternary Ti-Al-V-Cr alloys, the site occupancies of V and Cr do not show much mutual influence. In general, with increasing atomic number, elements in the same period show increasing tendency to substitute for Al, as is the tendency to substitute for Ti for elements in the same group of the periodic table. For Ti{sub 3}Al alloys, Ga and Sn atoms occupy Al sites, while V, Cr, Mn, Zr, Nb, Mo and Ta atoms occupy Ti sites, the site preference of V, Cr, Mn and Mo in TiAl alloys being different from that in Ti{sub 3}Al. The experimental results are interpreted in terms of a Bragg-Williams-type model and bond-order data obtained from electronic structure calculation. Qualitative agreement between the model and measurements is reached.

Hao, Y.L.; Xu, D.S.; Cui, Y.Y.; Yang, R.; Li, D. [Chinese Academy of Sciences, Shenyang (China). Inst. of Metal Research] [Chinese Academy of Sciences, Shenyang (China). Inst. of Metal Research

1999-03-10

413

Tuning of the Land g-factor in Al 1-xAs/AlAs single and double quantum wells  

E-print Network

Tuning of the Landé g-factor in Al xGa 1-xAs/AlAs single and double quantum wells This article has Contact us My IOPscience #12;Tuning of the Land´e g-factor in AlxGa1-xAs/AlAs single and double quantum wells F. G. G. Hernandez1, G. M. Gusev1, and A. K. Bakarov2 1 Instituto de F´isica, Universidade de S

Gusev, Guennady

414

The effect of grain size on the yield strength of FeAl and NiAl  

Microsoft Academic Search

This paper reports on the yield strength, [sigma][sub y], measured as a function of grain size, d, for a number of FeAl and NiAl alloys of different aluminum contents and the data fitted to the Hall-Petch relationship [sigma][sub y] = [sigma][sub 0] + kd[sup [minus] 1\\/2], where [sigma][sub 0] is the lattice resistance and k the Hall-Petch slope. For NiAl,

I. Baker; P. Nagpal; F. Liu; P. R. Munroe

1991-01-01

415

The effect of Ti\\/Al ratio on the site occupancies of alloying elements in ?-TiAl  

Microsoft Academic Search

The site occupancies of V, Cr, Mn, Fe, Ni, Zr, Nb, Ta, Mo, Ga and Sn (1?5 at%) in TiAl alloys with different nominal Ti\\/Al ratios were measured by the atom location channelling enhanced microanalysis (ALCHEMI) method. The results showed that Zr, Nb and Ta invariably occupy Ti sublattice sites, whereas Fe, Ni, Ga and Sn occupy Al sublattice sites,

Y. L Hao; R Yang; Y. Y Cui; D Li

2000-01-01

416

Electrostatic Mechanisms Responsible for Device Degradation in Proton Irradiated AlGaN\\/AlN\\/GaN HEMTs  

Microsoft Academic Search

Displacement-damage induced degradation in AlGaN\\/AlN\\/GaN HEMTs with polarization charge induced 2DEGs is examined using simulations and experiments. Carrier removal in the unintentionally doped AlGaN layer changes the space charge in the structure and this changes the band bending. The band bending decreases the 2DEG density, which in turn reduces the drain current in the device. The effect of the defect

A. Kalavagunta; A. Touboul; L. Shen; R. D. Schrimpf; R. A. Reed; D. M. Fleetwood; R. K. Jain; U. K. Mishra

2008-01-01

417

Formation of (Ti,Al)N/Ti{sub 2}AlN multilayers after annealing of TiN/TiAl(N) multilayers deposited by ion beam sputtering  

SciTech Connect

By using ion beam sputtering, TiN/TiAl(N) multilayers of various modulation wavelengths ({lambda}=8, 13, and 32 nm) were deposited onto silicon substrates at room temperature. After annealing at 600 deg. C in vacuum, one obtains for {lambda}=13 nm a (Ti,Al)N/Ti{sub 2}AlN multilayer as it is evidenced from x-ray diffraction, high resolution transmission electron microscopy, and energy filtered electron imaging experiments. X-ray photoelectron spectroscopy (XPS) experiments show that the as-deposited TiAl sublayers contain a noticeable amount of nitrogen atoms which mean concentration varies with the period {lambda}. They also evidenced the diffusion of aluminum into TiN sublayers after annealing. Deduced from these observations, we propose a model to explain why this solid-state phase transformation depends on the period {lambda} of the multilayer.

Dolique, V.; Jaouen, M.; Cabioc'h, T.; Pailloux, F.; Guerin, Ph. [Laboratoire de Metallurgie Physique, UMR 6630 du CNRS, Universite de Poitiers SP2MI, Bd Marie et Pierre Curie, Teleport 2, BP 30179, 86962 Futuroscope-Chasseneuil Cedex (France); Pelosin, V. [Laboratoire de Mecanique et de Physique des Materiaux, UMR 6617 du CNRS, ENSMA, 1 Avenue Clement Ader, Teleport 2, BP 40109, 86961 Futuroscope Chasseneuil Cedex (France)

2008-04-15

418

The wetting behavior of NiAl and NiPtAl on polycrystalline alumina  

SciTech Connect

In order to understand the beneficial effect of Pt on the adherence of thermally grown alumina scales, sessile drop experiments were performed to study the wetting of poly-crystalline alumina by nickel-aluminum alloys with or without platinum addition where the amount of Pt ranged from 2.4 to 10 at.%. Subsequent interfacial structure was evaluated using atomic force microscopy. Platinum addition enhances the wettability of NiAl alloys on alumina, reduces the oxide/alloy interface energy and increases the interfacial mass transport rates.

Saiz, Eduardo; Gauffier, Antoine; Saiz, Eduardo; Tomsia, Antoni P.; Hou, Peggy Y.

2007-07-01

419

Observation of overstrain in the coalescence zone of AlAs/AlOx oxidation fronts  

NASA Astrophysics Data System (ADS)

Strain from oxidation-induced volume shrinkage is studied by micro-photoluminescence. An InGaAs/GaAs quantum well (QW) placed at the vicinity of the selectively oxidized AlAs layer is used to probe the spatial distribution of the strain with a resolution of 1 µm. A QW wavelength shift of 1 nm imputed to the embedded strain is observed in agreement with finite element calculations. With this method, an overstrained zone is highlighted where the counter-propagative oxidation fronts merge.

Chouchane, F.; Almuneau, G.; Gauthier-Lafaye, O.; Monmayrant, A.; Arnoult, A.; Lacoste, G.; Fontaine, C.

2011-06-01

420

A G Barbeito et al. Motor neuron-immune interactions Motor neuron -immune interactions: the vicious circle of ALS  

E-print Network

of several neurodegenerative disorders including Amyotrophic Lateral Sclerosis, the most common motor neuron Introduction Amyotrophic Lateral Sclerosis (ALS) is a fatal neurodegenerative disease of the adult

421

Dislocation mechanism of high-temperature plastic deformation of Al–Cu–Fe and Al–Pd–Mn icosahedral quasicrystals  

Microsoft Academic Search

Microstructures in hot-impacted Al62.5Cu25Fe12.5 and Al70.4Pd21.2Mn8.4 icosahedral quasicrystals (IQCs) were studied by transmission electron microscopy (TEM). Densely distributed dislocations and stacking fault (SF) type contrast were observed for the first time in Al–Cu–Fe IQC. This result confirms that dislocation motion is an important deformation mechanism for Al–Cu–Fe IQC. Moving dislocations in quasicrystalline materials leave phason-type SFs behind. In situ TEM

Renhui Wang; Wenge Yang; Jianian Gui; Knut Urban

2000-01-01

422

Characteristics of a new BBOS with an AlGaAs-?(n+)-GaAs-InAlGaP collector structure  

Microsoft Academic Search

Two-terminal switching performances are observed in a new AlGaAs-GaAs-InAlGaP npn bulk-barrier optoelectronic switch (BBOS) with an AlGaAs-?(n+)-GaAs-InAlGaP collector structure. The device shows that the switching action takes place from a low-current state to a high-current state through a region of negative differential resistance (NDR). The transition from either state to the other may be induced by an appropriate optical or

Der-Feng Guo; Jing-Yuh Chen; Hung-Ming Chuang; Chun-Yuan Chen; Wen-Chau Liu

2004-01-01

423

Hybrid aluminum and indium conducting filaments for nonpolar resistive switching of Al/AlOx/indium tin oxide flexible device  

NASA Astrophysics Data System (ADS)

The nonpolar resistive switching characteristics of an Al/AlOx/indium tin oxide (ITO) device on a plastic flexible substrate are investigated. By analyzing the electron diffraction spectroscopy results and thermal coefficient of resistivity, it is discovered that the formation of aluminum and indium conducting filaments in AlOx film strongly depends on the polarity of the applied voltage. The metal ions arising from the Al and ITO electrodes respectively govern the resistive switching in corresponding operation polarity. After 104 times of mechanical bending, the device can perform satisfactorily in terms of resistance distribution, read sequence of high and low resistive states, and thermal retention properties.

Yuan, Fang; Wang, Jer-Chyi; Zhang, Zhigang; Ye, Yu-Ren; Pan, Liyang; Xu, Jun; Lai, Chao-Sung

2014-02-01

424

Laser irradiation of ZnO:Al/Ag/ZnO:Al multilayers for electrical isolation in thin film photovoltaics  

PubMed Central

Laser irradiation of ZnO:Al/Ag/ZnO:Al transparent contacts is investigated for segmentation purposes. The quality of the irradiated areas has been experimentally evaluated by separation resistance measurements, and the results are complemented with a thermal model used for numerical simulations of the laser process. The presence of the Ag interlayer plays two key effects on the laser scribing process by increasing the maximum temperature reached in the structure and accelerating the cool down process. These evidences can promote the use of ultra-thin ZnO:Al/Ag/ZnO:Al electrode in large-area products, such as for solar modules. PMID:24053228

2013-01-01

425

Deposition of TaAl-N Thin Film with Ta-Al Composite Target by Reactive Sputtering  

NASA Astrophysics Data System (ADS)

TaAl-N thin films prepared by DC reactive sputtering with Ta and Al composite target in a gas mixture of argon and nitrogen were investigated. The electrical properties of TaAl-N thin films could be controlled by the gas flow rate rario RN: RN=F(N2)/[F(N2)+F(Ar)]. Under the condition of RN lower than 25%, the TCR (the temperature coefficient of the resistivity) was constant at RT-300°C. The crystal structure of TaAl-N thin film was influenced by RN.

Okano, Yukiko; Tajiri, Shuichi; Aozono, Takashi; Okamoto, Akio; Ogawa, Soichi; Mima, Hiroshi

426

78 FR 6172 - In the Matter of the Designation of Ahmed Abdullah Saleh al-Khazmari al-Zahrani Also Known as Abu...  

Federal Register 2010, 2011, 2012, 2013

...Also Known as Abu Maryam al-Azadi Also Known as Ahmed bin Abdullah Saleh bin al-Zahrani Also Known as Ahmed Abdullah Saleh al...known as Abu Maryam al-Azadi, also known as Ahmed bin Abdullah Saleh bin al-Zahrani, also known as...

2013-01-29

427

CLADIERE et al Discharges of endocrine disrupting chemicals by  

E-print Network

of these pollutants within wastewater treatment plants (WWTP) and surface water are well documented (Ahel et al. 1994 receiving waters, wastewater treatment plant effluents have been widely studied. However, Although APEOs CSOs are known as an important source of pollutants into surface waters (Gasperi et al. 2010) and more

Boyer, Edmond

428

Mould et al., Page 1 Vision Research Author manuscript  

E-print Network

.h.foster@manchester.ac.uk. #12;Mould et al., Page 2 Vision Research Author manuscript Figure 1. A typical eye-movement traceMould et al., Page 1 Vision Research Author manuscript Author Manuscript Published in final edited form in Vision Research: Mould, M.S., Foster, D.H., Amano, K., & Oakley, J.P. (2012). A simple

Foster, David H.

429

STRUCTURE AND EXCITATIONS OF ORTHORHOMBIC Al 3 Co ERIC COCKAYNE  

E-print Network

STRUCTURE AND EXCITATIONS OF ORTHORHOMBIC Al 3 Co ERIC COCKAYNE Department of Applied Physics, Yale for each configuration is calculated by summing electronic structure based pair potentials. We apply this method to study Al 73 Co 24 in a 14.4 Å¡ A by 12.3 Å¡ A by 8.1 Å¡ A orthorhombic cell. The structures

Widom, Michael

430

Al-to-Cu Friction Stir Lap Welding  

NASA Astrophysics Data System (ADS)

Recently, friction stir welding (FSW) has been used frequently to join dissimilar metals, for instance, Al to Mg, Cu, and steel. The formation of brittle intermetallic compounds often severely limits the strength and ductility of the resultant welds. In the present study, Al-to-Cu lap FSW was studied by welding 6061 Al to commercially pure Cu. Conventional lap FSW was modified by butt welding a small piece of Al to the top of Cu, with a slight pin penetration into the bottom of Al. At travel speeds up to 127 mm/min (5 ipm), the modified welds were about twice the joint strength and five to nine times the ductility of the conventional lap welds. In the conventional lap welds, voids were present along the Al-Cu interface, and fracture occurred along the interface in tensile testing. No such voids were observed in the modified lap welds, and fracture occurred through Cu. Thus, as in the case of Al-to-Mg lap FSW recently studied by the authors, modified lap FSW significantly improved the weld quality in Al-to-Cu lap FSW. At the relatively high travel speed of 203 mm/min (8 ipm), however, modified lap FSW was no longer superior because of channel formation.

Firouzdor, Vahid; Kou, Sindo

2012-01-01

431

Lanthanide Al-Ni base Ericsson cycle magnetic refrigerants  

DOEpatents

A magnetic refrigerant for a magnetic refrigerator using the Ericsson thermodynamic cycle comprises DyAlNi and (Gd{sub 0.54}Er{sub 0.46})AlNi alloys having a relatively constant {Delta}Tmc over a wide temperature range. 16 figs.

Gschneidner, K.A. Jr.; Takeya, Hiroyuki

1995-10-31

432

Assessing the Incremental Algorithm: A Response to Krahmer et al.  

ERIC Educational Resources Information Center

This response discusses the experiment reported in Krahmer et al.'s Letter to the Editor of "Cognitive Science". We observe that their results do not tell us whether the Incremental Algorithm is better or worse than its competitors, and we speculate about implications for reference in complex domains, and for learning from "normal" (i.e.,…

van Deemter, Kees; Gatt, Albert; van der Sluis, Ielka; Power, Richard

2012-01-01

433

AlAs: effective Landé g-factors  

Microsoft Academic Search

This document is part of Volume 44 `Semiconductors', Subvolume A `New Data and Updates for I-VII, III-V, III-VI and IV-VI Compounds' of Landolt-Börnstein Group III `Condensed Matter'. It contains data on AlAs (aluminum arsenide), Element System Al-As.

E. C. Fernandes da Silva

2009-01-01

434

Oxidation behavior of FeAl+Hf,Zr,B  

NASA Technical Reports Server (NTRS)

The oxidation behavior of Fe-40Al-1Hf, Fe-40Al-1Hf-0.4B, and Fe-40Al-0.1Zr-0.4B (at. percent) alloys was characterized after 900, 1000, and 100 C exposures. Isothermal tests revealed parabolic kinetics after a period of transitional theta-alumina scale growth. The parabolic growth rates for the subsequent alpha-alumina scales were about five times higher than those for NiAl+0.1Zr alloys. The isothermally grown scales showed a propensity toward massive scale spallation due to both extensive rumpling from growth stresses and to an inner layer of HfO2. Cyclic oxidation for 200 1-hr cycles produced little degradation at 900 or 1000 C, but caused significant spallation at 1100 C in the form of small segments of the outer scale. The major difference in the cyclic oxidation of the three FeAl alloys was increased initial spallation for FeAl+Zr,B. Although these FeAl alloys showed many similarities to NiAl alloys, they were generally less oxidation resistant. It is believed that this resulted from nonoptimal levels of dopants and larger thermal expansion mismatch stresses.

Smialek, James L.; Doychak, Joseph

1988-01-01

435

Mechanical properties of Ru-Ni-Al alloys  

SciTech Connect

The Ru-Ni-Al system is significant for a number of reasons, not least of which is the interest in the ruthenium and nickel aluminides for high-temperature structural applications. The widely disparate properties of the B2 structured compounds NiAl and RuAl, in particular, have enjoyed extensive study. Whereas various factors, including a limited number of slip systems, conspire to render NiAl brittle at room temperature. Fleischer et al. have drawn attention to the unusual room-temperature ductility and toughness that RuAl exhibits in combination with high-temperature strength, specific stiffness, and oxidation resistance. Since alloys based on platinum group metals (PGMs) have apparent cost implications, some effort has been expended in seeking ways to replace some of the Ru without adversely affecting the intrinsic ductility. One approach is to seek some convergence in the properties of RuAl and its less ductile B2 counterparts by isostructural substitution for the Ru. In this regard, the existence of a B2 NiAl phase makes Ni an obvious candidate.

Wolff, I.M.; Sauthoff, G. [Max-Planck-Inst. fuer Eisenforschung GmbH, Duesseldorf (Germany)

1996-05-01

436

Al Qaeda, the Organization: A Five-Year Forecast  

Microsoft Academic Search

Al Qaeda today is a resilient organization, as evidenced by the London attacks of 2005, its resurgence in Pakistan, the deteriorating security situation in Afghanistan, and its influence on the war in Iraq. While al Qaeda is not strong enough to launch an attack inside the United States in the next five years, it will continue to train militants for

Peter Bergen

2008-01-01

437

Sputter deposition of TiC on TiAl  

SciTech Connect

Titanium aluminide, gamma-TiAl, is an advanced material developed for high temperature applications. To improve high temperature oxidation resistance of materials, various techniques have been proposed. Two prominent approaches are alloying element addition and coating. Silicon carbide, having excellent high temperature oxidation resisting characteristics, is suggested for use as coating on TiAl to promote its high temperature stability. For high temperature applications, it has been observed that SiC and titanium alloys easily form an interfacial reaction zone consisting of TiC. The direct contact between SiC and TiAl, thus, is considered undesirable when used at high temperatures. Since TiC is the reaction product between SiC and TiAl and since the CTE, coefficient of thermal expansion, of TiC, 7.5 [times] 10[sup [minus]6]/[degree]C, is between that of SiC, 4.5 [times] 10[sup [minus]6]/[degree]C, and TiAl, [approximately]10 [times] 10[sup [minus]6]/[degree]C, a TiC layer would provide a reasonable bridge between SiC and TiAl. It serves the purpose as a diffusion barrier and a functionally gradient interlayer. This study examines the application of TiC film with sputter deposition on the surface of TiAl as an intermediate layer before SiC is coated on TiAl specimens.

Chen, C.C.; Lin, R.Y. (Univ. of Cincinnati, OH (United States). Dept. of Materials Science and Engineering); Wu, S.K. (National Taiwan Univ., Taipei (Taiwan, Province of China). Inst. of Materials Engineering)

1994-03-01

438

Vacancy formation and effects in FeAl  

Microsoft Academic Search

Iron aluminide, FeAl, has been widely studied because of its excellent high temperature oxidation and corrosion properties. At high temperatures, FeAl generates a large number of thermal vacancies, and the vacancy concentration increases with increasing aluminum content. The mechanical properties depend on the vacancy concentration, so a thorough understanding of the generation and annihilation of vacancies is necessary. Heat treatment,

J. L. Jordan; S. C. Deevi

2003-01-01

439

Energetics of point defects in {gamma}-TiAl  

SciTech Connect

{gamma}TiAl has been receiving a great deal of attention in recent times owing to its industrial importance. This structural intermetallic is a candidate material for high temperature aerospace applications. Therefore, a study of point defect properties is useful in elucidating its physical metallurgy. In this brief communication, the authors discuss the vacancy and antisite defect properties of {gamma}-TiAl.

Raju, S.; Mohandas, E.; Raghunathan, V.S. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India)] [Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

1996-02-15

440

Al Prof. Luca Beltrametti Direttore del Dipartimento di Economia  

E-print Network

Mod. D3 Al Prof. Luca Beltrametti Direttore del Dipartimento di Economia Indirizzo Via Vivaldi 5, Darsena, Genova n. fax. 010 2095208 e-mail: direttore@economia.unige.it Oggetto: votazioni in data 18 Economia, con mandato fino al 31.10.2015. Richiesta di pubblicizzazione della disponibilità ad essere

Robbiano, Lorenzo

441

Gaseous modification of MCrAlY coatings  

SciTech Connect

The present invention generally describes methods for modifying MCrAlY coatings by using gaseous carburization, gaseous nitriding or gaseous carbonitriding. The modified MCrAlY coatings are useful in thermal barrier coating systems, which may be used in gas turbine engines.

Vance, Steven J. (Orlando, FL); Goedjen, John G. (Oviedo, FL); Sabol, Stephen M. (Orlando, FL); Sloan, Kelly M. (Longwood, FL)

2000-01-01

442

Al Qaeda in the Tribal Areas of Pakistan and Beyond  

Microsoft Academic Search

After the U.S. led coalition forces attacked Al Qaeda and Taliban infrastructure in Afghanistan beginning in October 2001, the epicenter of global terrorism moved from Afghanistan to tribal Pakistan. Known as the Federally Administered Tribal Area (FATA) in Pakistan, this region has emerged as the premier hunting ground for the Al Qaeda leadership. With the co-option of new groups in

Rohan Gunaratna; Anders Nielsen

2008-01-01

443

burke et al. CCD Imager Development for Astronomy  

E-print Network

· burke et al. CCD Imager Development for Astronomy 392 LINCOLN LABORATORY JOURNAL VOLUME 16;· burke et al. CCD Imager Development for Astronomy VOLUME 16, NUMBER 2, 2007 LINCOLN LABORATORY JOURNAL 393 CCD Imager Development for Astronomy Barry E. Burke, James A. Gregory, Michael Cooper, Andrew H

Reuter, Martin

444

Duong et al. ER and ER expression and transcriptional activity  

E-print Network

Duong et al. - 1 - ER and ER expression and transcriptional activity are differentially regulated 84 E-mail: lazennec@montp.inserm.fr or v.cavailles@montp.inserm.fr Abbreviations: ER.onc.1209102 #12;Duong et al. - 2 - ABSTRACT The proliferative action of ER largely accounts

Paris-Sud XI, Université de

445

Gibt es heute mehr epiphytische Moose als je zuvor?  

Microsoft Academic Search

Zusammenfassung: Die rapide Arten- als auch Mengenzunahme der Moosepiphyten in den letzten Jahren gerade in Städten stimulierte einen Vergleich der Häufigkeit der Arten früher (19. und 20. Jahrhundert) und den letzten 10 Jahren. Es zeigte sich, dass - hauptsächlich bezogen auf das Rheinland bzw. Nordrhein-Westfalen in letzter Zeit mehr Nachweise gemacht wurden als in den 150 Jahren zuvor. Grund ist

Jan-Peter Frahm

446

R. Jaff, et al.: Closing a major gap in the  

E-print Network

, 13 #12;Monday, May 6, 13 #12;HAMMES ET AL.: BLACK CARBON QUANTIFICATION RING TRIAL HAMMES ET AL.: BLACK CARBON QUANTIFICATION RING TRIAL Monday, May 6, 13 #12;http boreal forest after a fire has raged: where does the "charcoal" go? Credit and Larger Version April 18

Olver, Peter

447

A contact electromigration study of Al-Si-Cu alloys  

Microsoft Academic Search

With the advent of VLSI device density, new materials and technologies are being developed to ensure that interconnects and interlevel contacts are reliable. In addition to the use of Si-doped Al, barrier metallization has been introduced to prevent electromigration-induced junction spiking. To permit increased current densities, Cu has also been added to the Al alloy. It could be argued that

M. Repeta; J. Kolk; M. Saran; V. Q. Ho

1990-01-01

448

Scoring function to predict solubility mutagenesis Tian et al.  

E-print Network

Scoring function to predict solubility mutagenesis Tian et al. Tian et al. Algorithms for Molecular function to predict solubility mutagenesis Ye Tian1 , Christopher Deutsch2 , Bala Krishnamoorthy1* Abstract in the wild type (WT) protein, such as increased or decreased stability, reactivity, or solubility

Krishnamoorthy, Bala

449

A yeast functional screen predicts new candidate ALS disease genes  

PubMed Central

Amyotrophic lateral sclerosis (ALS) is a devastating and universally fatal neurodegenerative disease. Mutations in two related RNA-binding proteins, TDP-43 and FUS, that harbor prion-like domains, cause some forms of ALS. There are at least 213 human proteins harboring RNA recognition motifs, including FUS and TDP-43, raising the possibility that additional RNA-binding proteins might contribute to ALS pathogenesis. We performed a systematic survey of these proteins to find additional candidates similar to TDP-43 and FUS, followed by bioinformatics to predict prion-like domains in a subset of them. We sequenced one of these genes, TAF15, in patients with ALS and identified missense variants, which were absent in a large number of healthy controls. These disease-associated variants of TAF15 caused formation of cytoplasmic foci when expressed in primary cultures of spinal cord neurons. Very similar to TDP-43 and FUS, TAF15 aggregated in vitro and conferred neurodegeneration in Drosophila, with the ALS-linked variants having a more severe effect than wild type. Immunohistochemistry of postmortem spinal cord tissue revealed mislocalization of TAF15 in motor neurons of patients with ALS. We propose that aggregation-prone RNA-binding proteins might contribute very broadly to ALS pathogenesis and the genes identified in our yeast functional screen, coupled with prion-like domain prediction analysis, now provide a powerful resource to facilitate ALS disease gene discovery. PMID:22065782

Couthouis, Julien; Hart, Michael P.; Shorter, James; DeJesus-Hernandez, Mariely; Erion, Renske; Oristano, Rachel; Liu, Annie X.; Ramos, Daniel; Jethava, Niti; Hosangadi, Divya; Epstein, James; Chiang, Ashley; Diaz, Zamia; Nakaya, Tadashi; Ibrahim, Fadia; Kim, Hyung-Jun; Solski, Jennifer A.; Williams, Kelly L.; Mojsilovic-Petrovic, Jelena; Ingre, Caroline; Boylan, Kevin; Graff-Radford, Neill R.; Dickson, Dennis W.; Clay-Falcone, Dana; Elman, Lauren; McCluskey, Leo; Greene, Robert; Kalb, Robert G.; Lee, Virginia M.-Y.; Trojanowski, John Q.; Ludolph, Albert; Robberecht, Wim; Andersen, Peter M.; Nicholson, Garth A.; Blair, Ian P.; King, Oliver D.; Bonini, Nancy M.; Van Deerlin, Vivianna; Rademakers, Rosa; Mourelatos, Zissimos; Gitler, Aaron D.

2011-01-01

450

SCIENCE CAREER Al nanoclusters in coagulants and granulates: application  

E-print Network

treatment research, and their properties (e.g., high number of reactive surface binding sites) may make them a high reactivity due to a great number of OH- and H2O groups. This contribution evaluates these chemical Al13 Á Al30 1 Introduction The abundance of the carcinogenic arsenic in drinking and irrigation water

Wehrli, Bernhard

451

ALS: Family caregiver needs and quality of life.  

PubMed

The goal of this study was to determine the needs of ALS family caregivers. Utilizing a qualitative and quantitative mixed methodology known as Concept Mapping (CM), individual interviews with family caregivers of ALS patients (n =19) identified 109 needs. The needs were sorted and rated by 12 of the family caregivers, then analyzed using multidimensional scaling and cluster analysis. In addition, the caregivers completed the SF-8 QoL measure. The analysis resulted in a four-cluster map, representing the trajectory of the ALS family caregivers' needs: Stage 1: Early Coping and Adjustment; Stage 2: Maintenance; Stage 3: Transition to End Stage; and Stage 4: Coping with Change and Loss. The SF-8 results indicated that caregivers who resided with their ALS family member have poorer mental and physical health than family caregivers who did not have primary residence with the ALS patient. In conclusion, a model of needs for ALS family caregivers was established. Future studies addressing these needs may improve QoL of ALS family caregivers as well as ALS patients. PMID:18608102

Williams, Mary Tederous; Donnelly, James P; Holmlund, Tomas; Battaglia, Michael

2008-10-01

452

Buckley et al. 1 Ectothermy and endothermy Supplementary Material  

E-print Network

tolerance data was extracted from Sunday et al. (2010). For endotherm data sources, see table S2. The temperatures are lethal limits for ectotherms and the limits of the thermoneutral zone for endotherms. Seasonal S2 Endotherm thermal tolerance data. #12;Buckley et al. 2 Ectothermy and endothermy Bird and lizard

Hurlbert, Allen

453

Ecological studies on Al-Khadoud Spring, Al-Hassa, Saudi Arabia.  

PubMed

Al-Khadoud spring is one of the most important water resources in Al-Hassa Governorate, Saudi Arabia. However, much of its biotic information is still unknown. This study presented preliminary ecological information of this aquatic body. Regarding to macrophytes, a total of eight species were observed along the study sites. These species include two submerged aquatic plants (Potamogeton pectinatus L. and Ceratophyllum demersum L.). The common distributed species are Phragmites australis (Cav.) Trimex Steud and Cyperus rotundus (L.). On the other hand, a total of 20 algal genera were recorded with 7 genera of Chlorophyceae, 8 of Bacillariophyceae, 4 of Cyanophyceae and one of Euglenophyceae. The common phytoplankton occurred in all three investigated sites were Chlorella vulgaris, Mougeotia sp., Oscillatoria sp. and Actinastrum sp. Regarding to the biotic fauna, different forms of unicellular zooplankton such as Paramecium and Amoeba were recorded. Invertebrates such as freshwater insects and some freshwater snails were documented in the study sites including Melanodies tuberculata, Melanopsis praemorsa and Lymnaea auricularia. As regard to vertebrates, one species of fish, Aphanius dispar, dominate the spring basin and its extended channels. PMID:19090280

Al-Kahtani, Mohammed A; Youssef, Ashraf M; Fathi, Adel A

2007-11-15

454

Interface considerations in Al2O3/NiAl composite. Final report  

SciTech Connect

The fiber-matrix interface requirements in an Al2O3/NiAl composite were examined from theoretical considerations. Several factors that influence the interface bonding requirements were analyzed. These include: (1) residual stresses due to fiber-matrix coefficient of thermal expansion (CTE) mismatch; (2) matrix cracking stress at room temperature; (3) fracture toughness at room temperature; (4) load transfer from the matrix to the fiber and ultimate tensile strength at the use temperature; and (5) creep resistance at high temperature. A relatively weak fiber-matrix bond, with an interfacial shear strength of approximately 15-20 MPa, might be sufficient for attaining the desired mechanical properties in the fiber direction at the use temperature. A weak fiber-matrix bond is also beneficial for increasing the fracture toughness of the composite at room temperature. In contrast, a strong fiber-matrix bond is required to withstand some of the residual stresses resulting from the fiber-matrix CTE mismatch, which are not likely to be reduced significantly by interface coatings. A relatively strong bond is also beneficial in increasing the matrix cracking stress at room temperature. Various interface coating options to accommodate the conflicting bonding requirements were reviewed. One viable coating option is to incorporate a thick, ductile interface layer well bonded to both the fiber and the matrix.

Misra, A.K.

1993-07-01

455

De Novo Mutations in Ataxin-2 Gene and ALS Risk  

PubMed Central

Pathogenic CAG repeat expansion in the ataxin-2 gene (ATXN2) is the genetic cause of spinocerebellar ataxia type 2 (SCA2). Recently, it has been associated with Parkinsonism and increased genetic risk for amyotrophic lateral sclerosis (ALS). Here we report the association of de novo mutations in ATXN2 with autosomal dominant ALS. These findings support our previous conjectures based on population studies on the role of large normal ATXN2 alleles as the source for new mutations being involved in neurodegenerative pathologies associated with CAG expansions. The de novo mutations expanded from ALS/SCA2 non-risk alleles as proven by meta-analysis method. The ALS risk was associated with SCA2 alleles as well as with intermediate CAG lengths in the ATXN2. Higher risk for ALS was associated with pathogenic CAG repeat as revealed by meta-analysis. PMID:23936447

Laffita-Mesa, Jose Miguel; Rodriguez Pupo, Jorge Michel; Moreno Sera, Raciel; Vazquez Mojena, Yaimee; Kouri, Vivian; Laguna-Salvia, Leonides; Martinez-Godales, Michael; Valdevila Figueira, Jose A.; Bauer, Peter O.; Rodriguez-Labrada, Roberto; Zaldivar, Yanetza Gonzalez; Paucar, Martin; Svenningsson, Per; Perez, Luis Velazquez

2013-01-01

456

Electric quadrupole moment of the neutron-rich 33Al  

NASA Astrophysics Data System (ADS)

The nuclear electric quadrupole moment ( Q moment) of the neutron-rich nucleus 33Al ( I = 5/2 , T 1/2 = 41 ms) has been measured by the ? -ray detected nuclear quadrupole resonance ( ? -NQR) method for the first time. The 33Al nucleus is considered to be on the border of the island of inversion within which a significant intrusion of the pf orbits occurs across the N = 20 shell gap and the intrusion causes an anomalous enhancement of the Q moment. Polarized 33Al nuclei were produced from 36S (77.5MeV/ u beams through the fragmentation process and separated by LISE fragment separator at GANIL. The 33Al nuclei were implanted into a Al2O3 single-crystal plate and the ? -NQR spectrum was successfully obtained.

Nagatomo, T.; Shimada, K.; Asahi, K.; Balabanski, D. L.; Daugas, J. M.; Depuydt, M.; de Rydt, M.; Gaudefroy, L.; Grévy, S.; Hasama, Y.; Ichikawa, Y.; Kameda, D.; Morel, P.; Perrot, L.; Stödel, C.; Thomas, J. C.; Vanderheijden, W.; Vermeulen, N.; Vingerhoets, P.; Yoshimi, A.; Neyens, G.; Ueno, H.

2009-12-01

457

Molecular beam epitaxy growth of wurtzite AlN nanotips  

SciTech Connect

The characteristics of structure and morphology of AlN nanotips grown under higher V/III ratio on Si (111) with plasma-assisted molecular beam epitaxy are herein investigated. We found that the AlN nanotips were single crystalline with (1-211) inclined facets and embedded in pitlike defects of N-polarity. The density and size of the AlN nanotips can be controlled by the growth conditions. The AlN nanotip growth mechanism can be rationalized as the c-type dislocations generated between two adjacent grains due to the formation of higher strain area in the early stages of growth. The c-type dislocation would reverse the stacking sequence of the following adatoms, leading to the AlN nanotip growth with inverse polarity and higher growth rate compared to the surrounding matrix. These nanotips might serve as the ideal templates for further growth of nanostructure devices.

Hsu, K.-Y.; Liu, C.-P.; Chung, H.-C.; Chiu, Y.-C. [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China)

2008-11-03

458

Nanocrystalline NiAl Coating Prepared by HVOF Thermal Spraying  

NASA Astrophysics Data System (ADS)

Nanocrystalline NiAl intermetallic powder was prepared by mechanical alloying (MA) of Ni50Al50 powder mixture and then deposited on low carbon steel substrates by high velocity oxy fuel (HVOF) thermal spray technique using two sets of spraying parameters. X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), differential scanning calorimetry (DSC), and hardness test were used to characterize the prepared powders and coatings. The MA of Ni50Al50 powder mixture led to the formation of NiAl intermetallic compound. The resulting powder particles were three dimensional in nature with irregular morphology and a crystallite size of ~10 nm. This powder was thermally sprayed by HVOF technique to produce coating. The deposited coating had a nanocrystalline structure with low oxide and porosity contents. The hardness of coatings was in the range of 5.40-6.08 GPa, which is higher than that obtained for NiAl coating deposited using conventional powders.

Enayati, M. H.; Karimzadeh, F.; Tavoosi, M.; Movahedi, B.; Tahvilian, A.

2011-03-01

459

Investment casting of NiAl single-crystal alloys  

NASA Astrophysics Data System (ADS)

Significant progress has been made in the understanding of solidification conditions, microstructure evolution, and defect formation during investment casting of NiAl single crystals. The high liquidus temperatures of NiAl alloys result in a larger dendrite arm spacing than is found in superalloy René N5. Because of their higher thermal conductivities, NiAl alloys have higher cooling rates and lower temperature gradients during solidification than René N5. These differences give NiAl alloys a lower tendency to form freckles and a higher tendency to form equiaxed grains. However, with the aid of process modeling, single crystals of various shapes of NiAl alloys have been produced.

Yu, K. O.; Oti, J. A.; Walston, W. S.

1993-05-01

460

Comparative Genome-Wide Transcriptional Analysis of Al-Responsive Genes Reveals Novel Al Tolerance Mechanisms in Rice  

PubMed Central

Rice (Oryza sativa) is the most aluminum (Al)-tolerant crop among small-grain cereals, but the mechanism underlying its high Al resistance is still not well understood. To understand the mechanisms underlying high Al-tolerance, we performed a comparative genome-wide transcriptional analysis by comparing expression profiling between the Al-tolerance cultivar (Koshihikari) and an Al-sensitive mutant star1 (SENSITIVE TO AL RHIZOTOXICITY 1) in both the root tips and the basal roots. Exposure to 20 µM AlCl3 for 6 h resulted in up-regulation (higher than 3-fold) of 213 and 2015 genes including 185 common genes in the root tips of wild-type and the mutant, respectively. On the other hand, in the basal root, genes up-regulated by Al were 126 and 2419 including 76 common genes in the wild-type and the mutant, respectively. These results indicate that Al-response genes are not only restricted to the root tips, but also in the basal root region. Analysis with genes up- or down-regulated only in the wild-type reveals that there are other mechanisms for Al-tolerance except for a known transcription factor ART1-regulated one in rice. These mechanisms are related to nitrogen assimilation, secondary metabolite synthesis, cell-wall synthesis and ethylene synthesis. Although the exact roles of these putative tolerance genes remain to be examined, our data provide a platform for further work on Al-tolerance in rice. PMID:23110212

Tsutsui, Tomokazu; Yamaji, Naoki; Huang, Chao Feng; Motoyama, Ritsuko; Nagamura, Yoshiaki; Ma, Jian Feng

2012-01-01

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