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1

ANALISI DI STABILITÀ DEL MODELLO DI UN AUTOVETTURA  

Microsoft Academic Search

Sommario Il lavoro è incentrato sull'analisi di biforcazione di un modello di vettura che sta affrontando una curva. Il modello ha 2 gradi di libertà, e le sue equazioni contengono le non linearità dovute alla curve caratteristiche degli pneumatici. Dopo aver analizzato l'andamento degli equilibri al variare di un parametro tramite metodi di continuazione, viene fatta l'analisi di biforcazione al

Giampiero Mastinu; Fabio Della Rossa; Vitaliano Nobile

2

ANALISI TERMO-MECCANICA AGLI ELEMENTI FINITI DI UNA STRUTTURA INVESTITA DA FASCI DI PARTICELLE AD ALTA ENERGIA  

Microsoft Academic Search

Sommario Nel presente lavoro viene illustrata l'analisi termo-meccanica agli elementi finiti effettuata sui collimatori per il Large Hadron Collider, il potente acceleratore progettato al CERN di Ginevra; verranno esposte le scelte effettuate per i materiali e le soluzioni impiegate per il design dei collimatori di LHC. Verranno poi descritti il modello agli elementi finiti sviluppato, la metodologia di analisi adottata

A. Dallocchio; A. Bertarelli; L. Peroni

3

Impacto de la Ayuda Oficial al Desarrollo en Centroamerica  

Microsoft Academic Search

El presente trabajo pretende dar una vision de la situacion actual de la gestion de la Ayuda Oficial al desarrollo (AOD) y su impacto en la region de Centroamerica. Se analizan las similitudes y diferencias de los paises que la componen mediante la inclusion de indicadores que reflejan la situacion economica y social de la misma. El analisis se completa

Angelica Maria Valladares; Isabel Neira Gomez

2003-01-01

4

CORRELACION ENTRE METODOS DE ANALISIS DE Zn DISPONIBLE EN CUATRO ORDENES DE SUELOS DE COSTA RICA  

Microsoft Academic Search

Se realizo una comparacion entre metodos Evaluation of methods for available de analisis del Zn disponible en 4 ordenes de sue- Zn in four soil orders in Costa Rica. Analyti- los de Costa Rica (Ultisoles, Vertisoles, Andisoles cal methods for available Zn determination we- e Inceptisoles, 25 de c\\/u), utilizando las siguientes re evaluated on four soil orders in Costa

Eloy Molina; Elemer Bomemisza

5

Educación, estilo de vida y salud: un estudio aplicado al caso español  

Microsoft Academic Search

This work analyses the effects education has on the consumption of certain goods that have a bearing on health (particularly, alcohol and tobacco), and that in economic literature are part of the so-called non-monetary effects of education. The study carried out is based on data from the 1997 National Health Survey. The results indicate that, contrary to the principles of

Josep Oriol Escardíbul Ferrá; Jorge Calero Martínez; Facultad de Ciencias

2006-01-01

6

Dall' analisi matematica al calcolo geometrico: origini delle prime ricerche di logica di peano  

Microsoft Academic Search

The Calcolo geometrico (1888) seems to have been a turning point in the scientific career of Giuseppe Peano (1858–1932) because with this book he started publishing in logic. Looking for motivations of his early interests in the field one is naturally led to investigate the background of that book. Besides his previous work in mathematical analysis, methods and results of

Umberto Bottazzini

1985-01-01

7

Revision curricular a partir de un analisis comparativo de las discrepancias en los curriculos de una escuela de optometria en Puerto Rico con las competencias requeridas para las agencias de revalida y acreditacion 2004  

NASA Astrophysics Data System (ADS)

El proposito de esta investigacion, un estudio cualitativo de caso, fue comparar y contrastar el curriculo vigente de la Escuela de Optometria de la UIAPR con las competencias y estandares requeridos por las agencias de acreditacion y de revalida. Con este proposito, decidimos realizar una revision y un analisis de documentos: el prontuario de cada uno de los cursos de los curriculos implantados en el 1993 y en el 2001; las competencias y estandares establecidos por las agencias de revalida y de acreditacion; y las estadisticas en las que se analiza el porcentaje de estudiantes que aprueban cada una de las partes de los examenes de revalida entre el 1998 al 2003. Se realizaron entrevistas dirigidas para dar apoyo y complementar la revision y el analisis de estos documentos. Los participantes de las entrevistas fueron tres estudiantes de la clase de optometria del 2004 (ultima clase del curriculo del 1993); tres estudiantes de la clase de optometria del 2005 (primera clase graduanda del curriculo vigente) y tres profesores y/o directores de los Departamentos de Ciencias Basicas, Ciencias Clinicas y Cuidado al Paciente. Esta investigacion se enmarco en el modelo de evaluacion curricular de discrepancia de Malcolm Provus y en el modelo de desarrollo basado en competencias. Uno de los hallazgos mas importantes del estudio es que los cambios que se implantaron al curriculo del 2001 no han logrado que los estudiantes mejoren su ejecucion en los examenes de revalida. Por otro lado, se encontro que el curriculo vigente atiende completamente los estandares de la practica de Optometria, pero no las competencias. Esta informacion fue validada mediante el uso de una tabla de cotejo para el analisis de los cursos y de la informacion obtenida de las entrevistas. El estudio determina y concluye que existen discrepancias entre los prontuarios de los cursos del curriculo y las competencias requeridas por la agencia de revalida. Segundo, que el Departamento de Ciencias Basicas es el que presenta mas deficiencias en el desarrollo de las competencias. El investigador recomienda disenar e implantar un curriculo basado en competencias y proveer formacion en didactica y procesos de aprendizaje a los profesores.

Rivera Pacheco, Andres

8

DEFINIZIONE DI UNA PROVA DI ACCETTAZIONE SEMPLIFICATA ED ANALISI STATISTICA DEL COMPORTAMENTO VIBROACUSTICO DI RUOTE FERROVIARIE SMORZATE  

Microsoft Academic Search

Sommario Nel presente lavoro viene illustrata una procedura di accettazione di ruote ferroviarie trattate, nelle quali la ridotta emissione acustica è ottenuta mediante l'applicazione di uno smorzamento a strato vincolato mediante l'interposizione di un polimero viscoelastico fra il centro ruota ed un pannello di lamiera opportunamente sagomato. La procedura proposta è basata esclusivamente sull'analisi delle ampiezze di vibrazione in condizioni

A. Bracciali; S. Cervello; A. Rossi

9

I posti vacanti in Italia e in Europa. Le nuove statistiche trimestrali armonizzate: prime analisi delle serie storiche  

Microsoft Academic Search

1. Introduzione Le analisi sulle quantità nel mercato del lavoro sono state prevalentemente svolte dall'ottica dell'offerta di lavoro grazie alla disponibilità di dati rilevati dal lato delle famiglie. La principale di queste fonti di dati, l'indagine sulle forze di lavoro, permette di studiare approfonditamente l'evoluzione e la struttura delle tre componenti della popolazione in relazione ai diversi gradi di attachment

Ciro Baldi; Marina Sorrentino

10

RELACIÓN MICROESTRUCTURA RESISTENCIA AL DESGASTE DE RECUBRIMIENTOS DUROS RICOS EN CROMO Y TUNGSTENO APLICADOS POR SOLDADURA ELECTRICA (SMAW)  

Microsoft Academic Search

PALABRAS CLAVES: Recubrimientos duros, Carburos dispersos, Resistencia a la abrasión ABSTRACT: The microstructure and abrasive wear resistance of several hardfacing alloys were compared as a function of the chemical composition of the electrodes and the number of layers deposited onto ASTM A36 steel plates. High-Cr, low-Cr and high-W commercial electrodes were used, and the deposits were applied in one or

MARGARITA LEÓN SEVILLA; ALEJANDRO TORO

2004-01-01

11

Un'analisi dell'offerta elettrica al 2000. (Italian electric power supply to the year 2000).  

National Technical Information Service (NTIS)

This research deals with the structure of the electricity supply up to 2000, as it results out of the ENEL (Italian Electricity Board) and the National Energy Plan. The objective of the study is to analyze the options according to the different inputs of ...

L. Manfra

1989-01-01

12

ALS Association  

MedlinePLUS

... Read More » 2013 Walk to Defeat ALS® Fall Season Begins It's time to put on your walking ... Us Tweets by @alsassociation In The Spotlight Flu Season . . . and You It’s that time of year again! ...

13

AL Amyloidosis  

PubMed Central

Definition of the disease AL amyloidosis results from extra-cellular deposition of fibril-forming monoclonal immunoglobulin (Ig) light chains (LC) (most commonly of lambda isotype) usually secreted by a small plasma cell clone. Most patients have evidence of isolated monoclonal gammopathy or smoldering myeloma, and the occurrence of AL amyloidosis in patients with symptomatic multiple myeloma or other B-cell lymphoproliferative disorders is unusual. The key event in the development of AL amyloidosis is the change in the secondary or tertiary structure of an abnormal monoclonal LC, which results in instable conformation. This conformational change is responsible for abnormal folding of the LC, rich in ? leaves, which assemble into monomers that stack together to form amyloid fibrils. Epidemiology AL amyloidosis is the most common type of systemic amyloidois in developed countries with an estimated incidence of 9 cases/million inhabitant/year. The average age of diagnosed patients is 65 years and less than 10% of patients are under 50. Clinical description The clinical presentation is protean, because of the wide number of tissues or organs that may be affected. The most common presenting symptoms are asthenia and dyspnoea, which are poorly specific and may account for delayed diagnosis. Renal manifestations are the most frequent, affecting two thirds of patients at presentation. They are characterized by heavy proteinuria, with nephrotic syndrome and impaired renal function in half of the patients. Heart involvement, which is present at diagnosis in more than 50% of patients, leading to restrictive cardiopathy, is the most serious complication and engages prognosis. Diagnostic methods The diagnosis relies on pathological examination of an involved site showing Congo red-positive amyloid deposits, with typical apple-green birefringence under polarized light, that stain positive with an anti-LC antibody by immunohistochemistry and/or immunofluorescence. Due to the systemic nature of the disease, non-invasive biopsies such as abdominal fat aspiration should be considered before taking biopsies from involved organs, in order to reduce the risk of bleeding complications. Differential diagnosis Systemic AL amyloidosis should be distinguished from other diseases related to deposition of monoclonal LC, and from other forms of systemic amyloidosis. When pathological studies have failed to identify the nature of amyloid deposits, genetic studies should be performed to diagnose hereditary amyloidosis. Management Treatment of AL amyloidosis is based on chemotherapy, aimed at controlling the underlying plasma clone that produces amyloidogenic LC. The hematological response should be carefully checked by serial measurements of serum free LC. The association of an alkylating agent with high-dose dexamethasone has proven to be effective in two thirds of patients and is considered as the current reference treatment. New agents used in the treatment of multiple myeloma are under investigation and appear to increase hematological response rates. Symptomatic measures and supportive care is necessary in patients with organ failure. Noticeably, usual treatments for cardiac failure (i.e. calcium inhibitors, ?-blockers, angiotensin converting enzyme inhibitors) are inefficient or even dangerous in patients with amyloid heart disease, that should be managed using diuretics. Amiodarone and pace maker implantation should be considered in patients with rhythm or conduction abnormalities. In selected cases, heart and kidney transplantation may be associated with prolonged patient and graft survival. Prognosis Survival in AL amyloidosis depends on the spectrum of organ involvement (amyloid heart disease being the main prognosis factor), the severity of individual organs involved and haematological response to treatment.

2012-01-01

14

Application of Generalized Linear Models to Data Analysis in Drinking Water Treatment Aplicacion de modelos lineales generalizados al analisis de datos en el tratamiento de agua potable  

Microsoft Academic Search

In drinking water treatment we found appropriate linear models to ex- plain dose and concentration of sulphate, dose of lime, lime application prob- ability and polymer application probability, including as explanatory variables some physical and chemical properties of raw water.

Zulma Cepeda

2005-01-01

15

Prescrizione Farmaceutica in Umbria: Analisi dei Dati Relativi al 2005 (Pharmaceutical Prescription in Umbria (Italy): Analysis of the Data of 2005).  

National Technical Information Service (NTIS)

Aim of this report is to analyse the characteristics of drug prescription within the National Health Service of the Umbria region in 2005. In comparison to 2004 a 0.7% increase in the pharmaceutical expenditure was observed in Umbria (a corresponding 1.1%...

C. Romagnoli I. Abraha M. Rossi P. Ruggeri R. Da Cas

2006-01-01

16

ANALISIS SIFAT FOTOSENSITIVITAS SENYAWA ANTIBAKTERI TURUNAN FLUOROKUINOLON BERDASARKAN DATA TRANSISI ELEKTRONIK DAN SELISIH ENERGI ORBITAL HOMO-LUMO PHOTOSENSITIVITY ANALYSIS OF FLUOROQUINOLONE ANTIBACTERIAL COMPOUNDS BASED ON ELECTRONIC TRANSITIONS DATA AND HOMO-LUMO ENERGY BAND GAP  

Microsoft Academic Search

INTISARI Telah dilakukan analisis sifat fotosensitivitas dari senyawa antibakteri fluorokuinolon berdasarkan karakteristik spektra elektronik dan selisih energi HOMO-LUMO. Perhitungan spektra elektronik dilakukan menggunakan metode semiempirik ZINDO\\/s untuk mengetahui sifat fotosensitivitasnya pada daerah ultraviolet (?=200-400 nm) untuk molekul pada fasa gas dalam bentuk ion zwitter-nya. Perhitungan selisih energi HOMO-LUMO dilakukan untuk memprediksikan kekuatan fotosensitivitas dari senyawa antibakteri tersebut. Kedua proses perhitungan

Iqmal Tahir; Faiz El Makky; Harno Dwi Pranowo; Karna Wijaya

17

Precio del agua y relocalización del recurso en la economía andaluza. Una aproximación desde un modelo de equilibrio general aplicado  

Microsoft Academic Search

El objetivo de este trabajo consiste en analizar los efectos que tendría un incremento en la tarifa del agua del sector agrario sobre la conservación del recurso, la eficiencia en el consumo y la posible relocalización del mismo entre los diferentes sectores productivos. La política tarifaria se aplicará sobre el sector agrario debido, por un lado, al excesivo consumo de

M. Alejandro Cardenete; G. J. D. Hewings; E. Velázquez

2005-01-01

18

Amyotrophic Lateral Sclerosis (ALS)  

MedlinePLUS

... progressive, invariably fatal neurological disease that attacks the nerve cells (neurons) responsible for controlling voluntary muscles. In ALS, ... Information New gene mutations linked to ALS and nerve cell growth dysfunction Researchers have linked newly discovered gene ...

19

ALS longitudinal kickers  

SciTech Connect

This paper discusses the coupled-bunch instability and how it applies to the ALS accelerator. The longitudinal ALS kicker is part of the bunch-to-bunch feedback system planned to control coupled-bunch instabilities in the ALS. The mechanical features of the kicker are described, and the analytic tools developed to aid in the design are discussed. A method to predict the performance of the kicker in the accelerator from measurements on a prototype are described.

Voelker, F.

1992-10-01

20

Evolution of Al Qaeda.  

National Technical Information Service (NTIS)

Al Qaeda is a significant threat to the national security of the United States and its allies. This makes it important for individuals in these countries, both military and civilian, to understand the evolution of this threat. This thesis analyzes Al Qaed...

S. P. Wilson

2007-01-01

21

What Is ALS?  

MedlinePLUS

... to be involuntary. Remember, though, while you cannot stop your heart, you can hold your breath - so be aware ... trials that hold promise. Importantly, there are significant devices ... ALS ‘burns out,’ stops progressing or progresses at a very slow rate. ...

22

MDA ALS Caregiver's Guide  

MedlinePLUS

... day along the way. Lynne Nieto Corona del Mar, Calif. MDA ALS Division Co-Chair Publications Magazines ... 8 — Finding Caregiving Help Chapter 9 — End-of Life Issues Appendices MDA in Your Community Stay informed. ...

23

Iraq and Al Qaeda.  

National Technical Information Service (NTIS)

In building a case for invading Iraq and ousting Saddam Hussein from power, the Administration asserted that the regime of Saddam Hussein had a working relationship with the Al Qaeda organization. The Administration stated that the relationship dated to t...

K. Katzman

2007-01-01

24

Al-Qaeda  

Microsoft Academic Search

al-Qaeda, referred to as ‘the Base’ was founded in 1989 by Osama bin Laden and other like-thinking militant Muslims as the ultimate outcome of the 1979 invasion\\u000a of Afghanistan by the USSR. Initially, al-Qaeda was created to record and track down the names of the mujahideen listed as missing during the guerrilla war against the USSR.

Anne Rathbone; Charles K. Rowley

25

High temperature oxidation of mechanically alloyed NiAl–Fe–AlN–Al 2O 3  

Microsoft Academic Search

A new NiAl–Fe alloy containing uniformly distributed ultra-fine AlN and Al2O3 dispersoids was produced by mechanical alloying in a controlled atmosphere and by subsequent hot extrusion process. The new NiAl–Fe–AlN–Al2O3 alloy was oxidized in the temperature range between 1073 and 1473 K in air. The alloy displayed similar oxidation behavior with conventional NiAl alloys. As the oxidation temperature increased, the

D. B. Lee; G. Y. Kim; S. W. Park; S. C. Ur

2002-01-01

26

Microstructural characterization and tribocorrosion behaviour of Al\\/Al 3Ti and Al\\/Al 3Zr FGMs  

Microsoft Academic Search

Al\\/Al3Ti and Al\\/Al3Zr functionally graded materials (FGMs) were manufactured through a centrifugal method from Al–5 mass % Ti and Al–5 mass % Zr, respectively. Applied centrifugal forces were 30, 60 and 120 G (units of gravity). Microstructural characterization was performed and the influence of the reinforcing phase on the tribocorrosion behaviour of the FGMs was investigated. An increase in both

S. C. Ferreira; P. D. Sequeira; Yoshimi Watanabe; E. Ariza; L. A. Rocha

2011-01-01

27

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

28

ALS superbend magnet system  

SciTech Connect

The Lawrence Berkeley National Laboratory is preparing to upgrade the Advanced Light Source (ALS) with three superconducting dipoles (Superbends). In this paper we present the final magnet system design which incorporates R&D test results and addresses the ALS operational concerns of alignment, availability, and economy. The design incorporates conduction-cooled Nb-Ti windings and HTS current leads, epoxy-glass suspension straps, and a Gifford-McMahon cryocooler to supply steady state refrigeration. We also present the current status of fabrication and testing.

Zbasnik, J.; Wang, S.T.; Chen, J.Y.; DeVries, G.J.; DeMarco, R.; Fahmie, M.; Geyer, A.; Green, M.A.; Harkins, J.; Henderson, T.; Hinkson, J.; Hoyer, E.H.; Krupnick, J.; Marks, S.; Ottens, F.; Paterson, J.A.; Pipersky, P.; Portmann, G.; Robin, D.A.; Schlueter, R.D.; Steier, C.; Taylor, C.E.; Wahrer, R.

2000-09-15

29

Creep Behavior of Al-Rich Fe-Al Intermetallics.  

National Technical Information Service (NTIS)

The compression creep behavior of two dual-phase intermetallic alloys (FeAl2-Fe2Al5 and FeAl3-Fe2Al5) was investigated over the temperature range 600-1000 deg C. A normal primary creep stage, stress exponent between 4 and 5, and normal creep transient aft...

Y. L. Jeng E. J. Lavernia R. M. Hayes J. Wolfenstine

1995-01-01

30

Al/Al-oxide nanophase composites: Hardness and NMR Results  

NASA Astrophysics Data System (ADS)

Hardness and high temperature 27-Al NMR measurements of Al/Al-oxide nanophase composites produced by consolidation of nanoscale Al particles which have been passivated by exposure to air are reported. The Al/Al-oxide nanophase composite material produced has a low density, is electrically conducting and has a hardness much larger than that of metallic Al. High temperature NMR measurements show that the Al metal melts at the same temperature in all the samples, including a large-grained Al metal sample, independent of grain size and without a change in shape of the sample. The results here confirm previous thermal measurements which show that the Al metal melts without grain growth in these materials. On the other hand, the temperature for the onset of rapid atomic diffusion, as estimated from NMR line widths, shows a significant sample dependence. Heated samples exhibit a further factor of five increase in hardness and yet remain electrically conducting.

Suits, B. H.; Apte, P.

1998-03-01

31

Crustal and Upper Mantle S-velocity Structure From Receiver Functions Analisys Around Terra Nova Bay Base, Antartica  

NASA Astrophysics Data System (ADS)

In the framework of the italian PNRA (Progetto Nazionale di Ricerche in Antartide), we have started to re-analize teleseismic waveforms recorded, using three-components seismometers (equipped with 5 seconds sensors, Lennartz 3D-5s), during five summer campaings, from 1993 to 2000. Seismic stations were deployed around Terra Nova Bay (TNB) italian base, from the sea to reach the interior of the Transantartic Moun- tains (TAM), the most striking example of nocontractional mountain belt. During the last campaingn (1999-2000) seismic stations were deployed deep into Northern Vic- toria Land to reach Rennik and Lillie Glaciers Area and George V coast region, the northest part of TAM. Our main goals were: to compute, using frequency-domanin deconvolution method by Di Bona [1998], Receiver Functions covering all the area around TNB italian antartic base; to map of Moho-depth and intercrustal S-waves ve- locity discontinuity from 1-D velocity model computed using Sambridge's inversion scheme [Sambridge,1999]; to analize new teleseimic waveforms recorded near TNB base: continuos recording, from 1999 to present, permits more accurate modelling S-velocity crustal structure in this critical area situated at the edge of the ipothetic rift [Stern and ten Brik, 1989; Stump and Fitzgerald, 1992; ten Brik et al., 1997]; to present final results from BACKTAM expedition.

Piana Agostinetti, N.; Amato, A.; Cattaneo, M.; de Gori, P.; di Bona, M.

32

Unraveling Al Qaeda's Strategy.  

National Technical Information Service (NTIS)

Gauging the effectiveness of the U.S. strategy to counter international terrorism requires first an understanding of the objectives, ways and means, and implementation strategy of the adversary. In this case, the adversary is Al Qaeda and its network of a...

D. L. Shaffer

2005-01-01

33

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

34

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

35

Dar Al Islam Mosque  

Microsoft Academic Search

The mosque and school of the Dar Al Islam Foundation stand on a plateau above the Chama Valley, near the settlement of Abiquiu\\u000a to the north of the capital Sante Fe. The buildings and its inhabitants are part of a project that was initiated in the late\\u000a seventies. The project was born out of a Utopian notion of a liberal

Rudolf Stegers

36

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

37

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

38

Frequently Asked Questions about ALS and the ALS Registry  

MedlinePLUS

... on clinical trials? Questions About the ALS Registry Why was the registry created? Who created and is responsible for maintaining the ... Back to Top Questions About the ALS Registry Why was the ALS registry created? The registry was created as a tool to ...

39

Plasmonen als Lichttransporter: Nanooptik  

NASA Astrophysics Data System (ADS)

Metallische Nanopartikel, Nanodrähte oder Filme können Licht in Oberflächen-Plasmonen einfangen. Dieses Phänomen spielt sich im optischen Nahfeld und im Subwellenlängenbereich ab. Dabei entsteht ein hybrider, optoelektronischer Anregungszustand aus Licht und oszillierenden Leitungselektronen. Metallische Nanopartikel können zum Beispiel als Hilfsantennen die Fluoreszenz von Biomolekülen erheblich verstärken. Das ist für Fluoreszenzsensoren interessant. Experimente zeigen, dass metallische Nanodrähte in Oberflächen-Plasmonen Licht transportieren können. Auf zweidimensionalen, strukturierten Metallfilmen wurden Bauelemente bis hin zum Interferometer für Plasmonen erfolgreich demonstriert. Das junge Feld der Plasmonik könnte wichtige Beiträge zu einer zukünftigen Nanooptik liefern.

Aussenegg, Franz; Ditlbacher, Harald

2006-09-01

40

Doppelthydrophile Blockcopolymere als Mineralisationstemplate  

NASA Astrophysics Data System (ADS)

Die vorliegende Arbeit beschäftigt sich mit der Synthese und den Eigenschaften von doppelthydrophilen Blockcopolymeren und ihrer Anwendung in einem biomimetischen Mineralisationsprozeß von Calciumcarbonat und Bariumsulfat. Doppelthydrophile Blockcopolymere bestehen aus einem hydrophilen Block, der nicht mit Mineralien wechselwirkt und einem zweiten Polyelektrolyt-Block, der stark mit Mineraloberflächen wechselwirkt. Diese Blockcopolymere wurden durch ringöffnende Polymerisation von N-carboxyanhydriden (NCA's) und a-methoxy-?-amino[poly(ethylene glycol)] PEG-NH2 als Initiator hergestellt. Die hergestellten Blockcopolymere wurden als effektive Wachstumsmodifikatoren für die Kristallisation von Calciumcarbonat und Bariumsulfat Mineralien eingesetzt. Die so erhaltenen Mineralpartikel (Kugeln, Hantel, eiförmige Partikel) wurden durch Lichtmikroskopie in Lösung, SEM und TEM charakterisiert. Röntgenweitwinkelstreuung (WAXS) wurde verwendet, um die Modifikation von Calciumcarbonat zu ermitteln und die Größe der Calciumcarbonat- und Bariumsulfat-Nanopartikel zu ermitteln. This work describes the synthesis and characterization of double hydrophilic block copolymers and their use in a biomimetic mineralization process of Calcium Carbonate and Barium Sulfate. Double hydrophilic block copolymers consist of a hydrophilic block that does not interact with minerals and another hydrophilic polyelectrolyte block that strongly interacts with mineral surfaces. These polymers were synthesised via ring opening polymerisation of N-carboxyanhydride (NCA), and the first hydrophilic block a-methoxy-?-amino[poly(ethylene glycol)] PEG-NH2 was used as an initiator. The prepared block copolymers were used as effective crystal growth modifiers to control the crystallization of Calcium Carbonate and Barium Sulfate minerals. The resulting mineral particles (spheres, dumbbells, egg-like particles) were characterised by light microscopy in solution, by SEM, and by TEM. X-Ray scattering measurements (WAXS) were used to prove the modification of Calcium Carbonate particles and to calculate the size of Calcium Carbonate and Barium Sulfate nanoparticles.

Kasparova, Pavla

2002-07-01

41

Aplicacion de la espectrometria de alta resolucion de rayos x precedida por la activacion neutronica al analisis elemental de suelos. (Application of high resolution x-ray spectrometry preceded by neutron activation for elemental analysis of soil samples).  

National Technical Information Service (NTIS)

Utilization of High Resolution X-Ray Spectrometry preceded by activation of the samples by irradiation with neutron fluxes (NAA(sub R)X) is a relatively modern trend in application of nuclear techniques. This method may complement advantageously the usual...

A. Hernandez Rivero G. Capote Rodriguez E. Herrera Peraza

1996-01-01

42

Metodos de analisis numerico de espectros alfa y aplicacion al estudio del neptunium 237 y neptunium 236. (Numerical methods to analyze alpha spectra and application to the study of neptunium 237 and neptunium 236).  

National Technical Information Service (NTIS)

A set of numerical methods to analize alpha spectra measured with semiconductor detectors are presented. The methods can be divided in two groups, the first being based in the X(sup 2) minimization ands the second in the use of the Fourier Transform. The ...

E. Garcia-Torano

1990-01-01

43

Determinacion de Cr, Mn, Si y Ni en aceros al carbono por analisis espectral de emision con fuente de chispa. (Determination of Cr, Mn, Si, and Ni in carbon steels by optical emission spectrometry with spark source).  

National Technical Information Service (NTIS)

Elemental composition of steels determines some important of his characteristic moreover it is necessary to obtain their quality certification. Analytical procedure has performed for determination of Cr, Mn, Si and Ni in carbon steels by optical emission ...

M. A. Garcia Gonzalez M. Pomares Alfonso L. Mora Lopez

1995-01-01

44

Detecting frontotemporal dysfunction in ALS: utility of the ALS Cognitive Behavioral Screen (ALS-CBS).  

PubMed

Up to half of patients with ALS develop cognitive impairment during the course of the illness. Despite this, there is no simple tool for screening patients in the clinical setting. This study examines the sensitivity, specificity and accuracy of the ALS Cognitive Behavioral Screen (ALS-CBS). We administered the measure to 112 ALS patients, including 31 who also underwent comprehensive neuropsychological testing. Screen results were validated by determining the accuracy against the full battery. Optimal cut-off scores for predicting the correct diagnosis were determined, and mean scores were compared between patients, controls and different diagnostic groups. The results demonstrated that mean cognitive scores differed between ALS and normal controls (p < 0.0001). The cognitive section differentiated ALS-FTD from other ALS patients with 100% accuracy. Cognitively normal ALS patients could be distinguished from those with any cognitive deficit with 71% specificity and 85% sensitivity. A separate behavioral score was significantly lower in the ALS cohort compared to controls (p < 0.0001) and predicted ALS-FTD with 80% sensitivity and 88% specificity. In conclusion, the ALS-CBS can aid in detecting cognitive and behavioral impairment in a clinical setting, although it does not replace formal diagnostic assessment. Further validation with larger sample sizes will clarify its clinical utility. PMID:20433413

Woolley, Susan C; York, Michele K; Moore, Dan H; Strutt, Adriana M; Murphy, Jennifer; Schulz, Paul E; Katz, Jonathan S

2010-05-01

45

Interfacial reactions and oxidation behavior of Al 2O 3 and Al 2O 3/Al coatings on an orthorhombic Ti 2AlNb alloy  

NASA Astrophysics Data System (ADS)

The uniform and dense Al 2O 3 and Al 2O 3/Al coatings were deposited on an orthorhombic Ti 2AlNb alloy by filtered arc ion plating. The interfacial reactions of the Al 2O 3/Ti 2AlNb and Al 2O 3/Al/Ti 2AlNb specimens after vacuum annealing at 750 °C were studied. In the Al 2O 3/Ti 2AlNb specimens, the Al 2O 3 coating decomposed significantly due to reaction between the Al 2O 3 coating and the O-Ti 2AlNb substrate. In the Al 2O 3/Al/Ti 2AlNb specimens, a ?-TiAl layer and an Nb-rich zone came into being by interdiffusion between the Al layer and the O-Ti 2AlNb substrate. The ?-TiAl layer is chemically compatible with Al 2O 3, with no decomposition of Al 2O 3 being detected. No internal oxidation or oxygen and nitrogen dissolution zone was observed in the O-Ti 2AlNb alloy. The Al 2O 3/Al/Ti 2AlNb specimens exhibited excellent oxidation resistance at 750 °C.

Li, H. Q.; Wang, Q. M.; Gong, J.; Sun, C.

2011-02-01

46

„Leistung“ als Aktion und Präsentation  

Microsoft Academic Search

\\u000a Zusammenfassungen  Die sprachanalytische Untersuchung des Begriffs „Leistung“ führt zu der Konzeption einer „Philosophie der Leistung“ als einer\\u000a Theorienormativer Aussagen über „Leistung“. Handlungen werden anhand bestimmter Kriterien als „Leistungen“ identifiziert; es kommt daher der Präsentation dieser Aktionen\\u000a als „Leistungen“ Bedeutung zu: Eine „Leistung“ besteht immer aus einer „Aktions-“ und einer „Präsentations-Leistung“. Insbesondere\\u000a die „Präsentations-Leistung“ erfüllt eine entscheidende Funktion bei der Konstitution von

Gunter Gebauer

1972-01-01

47

Microstructures and properties of Al 2O 3\\/Al–AlN composites by pressureless infiltration of Al-alloys  

Microsoft Academic Search

Al alloys were infiltrated into Al2O3 preforms in N2 and N2– 2% H2 gas mixture in the temperature regime of 900–1200°C. The kinetics of nitridation during infiltration were continuously monitored by recording weight gained during infiltration of the preform. The weight gains that are attributed to the formation of AlN in the matrix were observed to increase with processing temperature.

N Nagendra; B. S Rao; V Jayaram

1999-01-01

48

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

49

AL Amyloidosis with Renal Involvement  

Microsoft Academic Search

Primary (AL amyloidosis) is a systemic disease characterized by an amyloid deposition process in many organs, with unsatisfactory survival of patients. The monoclonal light chains form the fibrils that deposit and accumulate in tissues. Renal involvement is very frequent in AL amyloidosis and could lead to development of nephrotic syndrome followed by the renal failure in many cases. Classic therapeutic

Romana Ryšavá

2007-01-01

50

AlN Substrate Applications.  

National Technical Information Service (NTIS)

The types of presently available AlN substrates are outlined along with the precautions to be taken in using them. Also discussed in detail are the factors to be considered in planning the introduction of AlN substrates and the structures, properties and ...

N. Iwase

1988-01-01

51

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

52

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

53

The Advanced Launch System (ALS)  

NASA Astrophysics Data System (ADS)

The Advanced Launch System (ALS) is an unmanned vehicle that will achieve low hardware cost by using a reusable booster stage which flies back to the launch site, and a core stage in which the rocket engines and redundant avionics are in a module that is returned to earth and recovered for reuse. The booster's utilization of liquid propellant instead of solid propellant will help lower the consumable costs. The ALS also includes launch processing and flight control facilities, necessary support equipment, and ground- and flight-operations infrastructure. The ALS program studies show that, through the ALS, the United States can launch a major Mars initiative economically and with confidence. It is estimated that the objective ALS can be operational in the late 1990s.

Eldred, Charles H.

54

Stimulated emission in AlGaN/AlGaN quantum wells with different Al content  

NASA Astrophysics Data System (ADS)

Stimulated emission (SE) is studied in AlGaN/AlGaN multiple quantum wells (MQWs) with different Al content grown on sapphire substrate. The spectra of spontaneous and stimulated emission and their transformations with increasing temperature as well as stimulated emission thresholds were measured in the temperature range from 8 to 300 K. Phonon-assisted band broadening in low-Al-content MQWs and double-scaled potential profile in high-Al-content MQWs were observed in the samples and linked with carrier localization conditions. The temperature dependence of the stimulated emission threshold was similar in the samples where the stimulated transitions occur between extended states and in the samples where the transitions occur in localized states. The stimulated emission threshold depends predominantly on the density of nonradiative recombination centers.

Mickevi?ius, J.; Jurkevi?ius, J.; Kazlauskas, K.; Žukauskas, A.; Tamulaitis, G.; Shur, M. S.; Shatalov, M.; Yang, J.; Gaska, R.

2012-02-01

55

Analisis multielemental por activacion neutronica de sedimentos del Golfo de Ana Maria. (Multielemental analysis by neutron activation of sediments in the Ana Maria Gulf, Cuba).  

National Technical Information Service (NTIS)

In this paper general samples of marine sediments taken from six control stations of the Ana Maria Gulf (Cuba) were analyzed. For this purpose the thermal neutron activation analysis method was used. 18 elements were determinated. They are: Al, Ce, Co, Cs...

O. Diaz Rizo D. Gandarias R. Calzavilla G. Garcia

1990-01-01

56

ANALISI DEI PROFILI DI MISSIONE PER VEICOLI MILITARI. DEFINIZIONE E VALIDAZIONE DI STRUMENTI PER LA SINTESI DI CONDIZIONI DI CARICO EQUIVALENTI  

Microsoft Academic Search

Sommario Obiettivo della presente memoria è stata l'individuazione delle condizioni di carico da utilizzare per verificare il comportamento di veicoli militari in fase di progetto. Ciò significa individuare dei percorsi di prova (test tracks o condizioni di carico), le associate velocità di percorrenza ed il relativo chilometraggio al fine di definire una loro combinazione (test ring o combinazione di carico)

C. Braccesi; F. Cianetti; L. Silvioni

57

Al Cu Texture Enhancement by Underlayer Texture  

Microsoft Academic Search

Al Cu layered films and interconnections (Al\\/underlayers) were fabricated and investigatedto observe the effects of underlayer texture on Al texture development and of Al texture onelectromigration resistance. Al(111) texture was enhanced by controlling Ti and TiNunderlayer textures. Values of full width at half maximum for Al(111) rocking curves rangedfrom 0.64° to 4.7° for Al Cu films grown on Ti, TiN\\/Ti,

Tsutomu Sasaki; Hitoshi Dohnomae

1998-01-01

58

Comparing the Thermodynamic Behaviour of Al(1)+ZrO2(s) to Al(1)+Al2O3(s).  

National Technical Information Service (NTIS)

In an effort to better determine the thermodynamic properties of Al(g) and Al2O(g). the vapor in equilibrium with Al(l)+ZrO2(s) was compared to the vapor in equilibrium with Al(l)+Al2O3(s) over temperature range 1197-to-1509K. The comparison was made dire...

E. Copland

2004-01-01

59

Genetic inroads in familial ALS.  

PubMed

Amyotrophic lateral sclerosis (ALS) is a common neurodegenerative disease causing cell death of motor neurons and progressive muscle weakness. The disease is familial in ten percent of cases, of which one-fifth are due to mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1). Two papers in this issue of Nature Genetics describe homozygous mutations in a new gene on chromosome 2q33 in 4 families of Arabian origin with a rare form of juvenile onset ALS (ALS2). The predicted protein structure has domains homologous to GTPase regulatory proteins, and both the types of mutation and the pattern of inheritance suggest that motor neuron degeneration is the result of a loss of function. Further work will determine the relevance of this breakthrough to other, more common forms of ALS. PMID:11586285

Shaw, P J

2001-10-01

60

Transcranial magnetic stimulation in ALS  

PubMed Central

Objective: To investigate transcranial magnetic stimulation (TMS) measures as clinical correlates and longitudinal markers of amyotrophic lateral sclerosis (ALS). Methods: We prospectively studied 60 patients with ALS subtypes (sporadic ALS, familial ALS, progressive muscular atrophy, and primary lateral sclerosis) using single pulse TMS, recording from abductor digiti minimi (ADM) and tibialis anterior (TA) muscles. We evaluated three measures: 1) TMS motor response threshold to the ADM, 2) central motor conduction time (CMCT), and 3) motor evoked potential amplitude (correcting for peripheral changes). Patients were evaluated at baseline, compared with controls, and followed every 3 months for up to six visits. Changes were analyzed using generalized estimation equations to test linear trends with time. Results: TMS threshold, CMCT, and TMS amplitude correlated (p < 0.05) with clinical upper motor neuron (UMN) signs at baseline and were different (p < 0.05) from normal controls in at least one response. Seventy-eight percent of patients with UMN (41/52) and 50% (4/8) of patients without clinical UMN signs had prolonged CMCT. All three measures revealed significant deterioration over time: TMS amplitude showed the greatest change, decreasing 8% per month; threshold increased 1.8% per month; and CMCT increased by 0.9% per month. Conclusions: Transcranial magnetic stimulation (TMS) findings, particularly TMS amplitude, can objectively discriminate corticospinal tract involvement in amyotrophic lateral sclerosis (ALS) from controls and assess the progression of ALS. While central motor conduction time and response threshold worsen by less than 2% per month, TMS amplitude decrease averages 8% per month, and may be a useful objective marker of disease progression. GLOSSARY ADM = abductor digiti minimi; ALS = amyotrophic lateral sclerosis; ANOVA = analysis of variance; CI = confidence interval; CMAP = compound motor action potential; CMCT = central motor conduction time; DTR = deep tendon stretch reflex; fALS = familial ALS; GEE = generalized estimation equations; LMN = lower motor neuron; MEP = motor evoked potential; PLS = primary lateral sclerosis; PMA = progressive muscular atrophy; sALS = sporadic ALS; TA = tibialis anterior; TMS = transcranial magnetic stimulation; UMN = upper motor neuron.

Floyd, A G.; Yu, Q P.; Piboolnurak, P; Tang, M X.; Fang, Y; Smith, W A.; Yim, J; Rowland, L P.; Mitsumoto, H; Pullman, S L.

2009-01-01

61

MADINAT AL-ZAHRAí: INVESTIGACI\\  

Microsoft Academic Search

The virtual reconstruction of the archeological site of Mad inat al-Zahraí in CÛrdoba (Spain) has permitted a new approach to the study and comprehension of this palatine city as well as to the typologies of Islamic architecture in Al-Andalus during the 10th century. Starting from fieldwork and from a photogrammetric survey of the site, the digital model has become a

Antonio Almagro Gorbea; Ana Almagro Vidal

62

Befähigungsgerechtigkeit als Ermöglichung gesellschaftlicher Inklusion  

Microsoft Academic Search

Soziale Gerechtigkeit gilt vielen — vor allem in Deutschland — noch immer als ein zuhöchst attraktiver Wert politischen Zusammenlebens,\\u000a der auch als gesellschaftliche Norm zu etablieren sei. Nicht nur in der politischen Rhetorik, sondern auch in der Sozialtheorie\\u000a und politischen Philosophie schillert der Begriff vielfach. Er ringt vor dem anthropologisch nicht zu bestreitenden Spannungsverhältnis\\u000a von Kooperationswilligkeit und Konkurrenz- und Konfliktbeladenheit

Peter Dabrock

63

Befähigungsgerechtigkeit als Ermöglichung gesellschaftlicher Inklusion  

Microsoft Academic Search

Soziale Gerechtigkeit gilt vielen – vor allem in Deutschland – noch immer als ein zuhöchst attraktiver Wert politischen Zusammenlebens,\\u000a der auch als gesellschaftliche Norm zu etablieren sei. Nicht nur in der politischen Rhetorik, sondern auch in der Sozialtheorie\\u000a und politischen Philosophie schillert der Begriff vielfach. Er ringt vor dem anthropologisch nicht zu bestreitenden Spannungsverhältnis\\u000a von Kooperationswilligkeit und Konkurrenz- und Konfliktbeladenheit

Peter Dabrock

64

FTD and ALS: genetic ties that bind.  

PubMed

Curiously, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), seemingly disparate neurodegenerative disorders, can be inherited together. Two groups (DeJesus-Hernandez et al. and Renton et al.) show that the long sought after ALS/FTD mutation on chromosomal region 9p is a hexanucleotide expansion in C90RF72. These studies, plus a study on X-linked ALS/FTD, provide molecular starting points for identifying pathways that link ALS and FTD pathogenesis. PMID:22017980

Orr, Harry T

2011-10-20

65

AL1-dependent repression of transcription enhances expression of Tomato golden mosaic virus AL2 and AL3  

PubMed Central

Studies using Nicotiana benthamiana protoplasts have determined that repression of upstream transcription by AL1 protein enhances AL2 and AL3 expression in Tomato golden mosaic virus (TGMV). Mutations resulting in the inability of TGMV AL1 protein to associate with its cognate binding site, result in a decrease in both AL2 and AL3 expression. Reduced expression correlates with an increase in transcription from the AL62 start site, and decreased transcription from downstream initiation sites (AL1935 and AL1629) present within the AL1 coding region. The results demonstrate that, in a tobacco protoplast system, repression of AL62 transcription, regulated through binding of AL1 protein to sequences in the origin of replication, is required prior to AL2 and AL3 gene expression from the AL1935 and AL1629 viral transcripts. This provides a mechanism to regulate expression of AL2, which is involved in suppression of host defense responses and is required for late gene expression.

Shung, Chia-Yi; Sunter, Garry

2010-01-01

66

Muqtada al-Sadr: How to Demilitarize al-Sadr.  

National Technical Information Service (NTIS)

Muqtada al-Sadr has been one of the most influential individuals in Iraq since the U.S. invasion in March 2003. His Mahdi Army has actively confronted coalition forces and engaged in ethnic cleansing that has resulted in the displacement of thousands of I...

M. E. Hollinger

2009-01-01

67

Powder Metallurgy Processing of Dual Phase Al Rich Fe-Al Intermetallics.  

National Technical Information Service (NTIS)

A powder metallurgy technique was used to fabricate two different dual-phase Al-rich Fe-Al intermetallics, namely, FeAl2-Fe2Al5 and FeAl3-Fe2Al5. Powders were first produced by inert gas atomization, and then subsequently consolidated by hot pressing at 1...

Y. L. Jeng R. Hayes J. Wolfenstine E. J. Lavernia

1995-01-01

68

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

69

Andalusian astronomy: al-Zij al-Muqtabis of Ibn al-Kammâd.  

NASA Astrophysics Data System (ADS)

In the twelfth century the Arabic astronomer Ibn al-Kammâd, living in Islamic Spain, composed three sets of astronomical tables, called "zijes". The zijes were largely based on the work of predecessors, going back to Ptolemy on the one hand, and Hindu astronomers on the other. None of his zijes survived in the original Arabic, but a Latin manuscript contains a translation of an apparently complete zij, the "al-Zij al-Muqtabis". This paper examines the body of astronomical knowledge contained in this zij. Specifically, it is shown that one can gain valuable information on the solar theory of the Islamic astronomers from this translation. Furthermore, the theory of lunar and solar eclipses in the work is analyzed, and tables of mean planetary and solar motions are discussed. In addition, tables for the motion of the vernal equinox, star tables, and several topics of Islamic spherical astronomy are examined.

Chabás, J.; Goldstein, B. R.

1994-12-01

70

Glutamate Receptor Aptamers and ALS.  

National Technical Information Service (NTIS)

Excitotoxicity is one of the leading causes for amyotrophic lateral sclerosis (ALS). Our goal was to develop a novel class of powerful aptamer- based, anti-excitotoxic inhibitors against GluR2Qflip, a key AMPA receptor subunit that controls the calcium pe...

L. Niu

2009-01-01

71

Glutamate Receptor Aptamers and ALS.  

National Technical Information Service (NTIS)

Excitotoxicity is one of the leading causes for amyotrophic lateral sclerosis (ALS). Our goal was to develop a novel class of powerful aptamer- based anti-excitotoxic inhibitors against GluR2Qflip a key AMPA receptor subunit that controls the calcium perm...

L. Niu

2008-01-01

72

Interview with Mumna Al Banchaabouchi  

NSDL National Science Digital Library

An interview with Dr Mumna Al Banchaabouchi, researcher in the Mouse Phenotyping Core at EMBL in Monterotondo Italy. This video is two minutes and 55 seconds in length, and available in Quicktime (25 MB) and Windows Media Player (29 MB). All Stem Cells videos are located at: http://www.hhmi.org/biointeractive/stemcells/video.html.

Howard Hughes Medical Institute (Howard Hughes Medical Institute;)

2007-03-31

73

Cómo hacer frente al cáncer  

Cancer.gov

Existen muchos recursos de ayuda y apoyo para las personas con cáncer, sus familiares y amigos. Infórmese sobre las reacciones psicológicas al cáncer y la forma de hacer frente a estas situaciones. Conozca los servicios que ofrecen las comunidades locales y las organizaciones nacionales para ayudarle con los diferentes aspectos del tratamiento y la recuperación del cáncer.

74

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

75

Dry sliding wear behaviour of Al–12Si and Al–12Si–3Cu cast alloys  

Microsoft Academic Search

This paper attempts to investigate the influence of the microstructural changes on the dry sliding wear behaviour of Al–12Si and Al–12Si–3Cu cast alloys by grain refinement (Al–1Ti–3B), modification (Al–10Sr) and combined action of both (Al–1Ti–3B+Al–10Sr). Results indicate that combined grain refined and modified Al–12Si–3Cu cast alloys have microstructures consisting of uniformly distributed ?-Al grains, eutectic Al–silicon and fine CuAl2 particles

K. G. Basavakumar; P. G. Mukunda; M. Chakraborty

2009-01-01

76

Molecular Dynamics Study of Velocity Dependence of Sliding Friction at Al/Al and Al2O3/Al2O3 Interface  

NASA Astrophysics Data System (ADS)

Using the newly developed reactive force field, the static and kinetic friction behavior of Al/Al (flat and rough), Al2O3/Al2O3 (commensurate and incommensurate) interfaces have been studied by molecular dynamics simulations. It is found that the commensurate Al2O3/Al2O3 interface has higher friction than incommensurate Al2O3/Al2O3 interface. For both interfaces, at lower velocities, friction exhibits dry friction, whereas above a critical speed, the velocity dependence follows a viscous relation. For Al/Al flat interface, only viscous friction is observed. Roughness on the surface would increase friction and change velocity dependence. The simulation results indicate that the different behaviors of velocity dependence are from the interfacial interaction or potential surface for these friction samples. The origin of static friction is also discussed.

Zhang, Qing; Cagin, Tahir; Goddard, William A.; Qi, Yue; Hector, Louis G.

2004-03-01

77

Identification of Candida albicans ALS2 and ALS4 and Localization of Als Proteins to the Fungal Cell Surface  

PubMed Central

Additional genes in the growing ALS family of Candida albicans were isolated by PCR screening of a genomic fosmid library with primers designed from the consensus tandem-repeat sequence of ALS1. This procedure yielded fosmids encoding ALS2 and ALS4. ALS2 and ALS4 conformed to the three-domain structure of ALS genes, which consists of a central domain of tandemly repeated copies of a 108-bp motif, an upstream domain of highly conserved sequences, and a domain of divergent sequences 3? of the tandem repeats. Alignment of five predicted Als protein sequences indicated conservation of N- and C-terminal hydrophobic regions which have the hallmarks of secretory signal sequences and glycosylphosphatidylinositol addition sites, respectively. Heterologous expression of an N-terminal fragment of Als1p in Saccharomyces cerevisiae demonstrated function of the putative signal sequence with cleavage following Ala17. This signal sequence cleavage site was conserved in the four other Als proteins analyzed, suggesting identical processing of each protein. Primary-structure features of the five Als proteins suggested a cell-surface localization, which was confirmed by indirect immunofluorescence with an anti-Als antiserum. Staining was observed on mother yeasts and germ tubes, although the intensity of staining on the mother yeast decreased with elongation of the germ tube. Similar to other ALS genes, ALS2 and ALS4 were differentially regulated. ALS4 expression was correlated with the growth phase of the culture; ALS2 expression was not observed under many different in vitro growth conditions. The data presented here demonstrate that ALS genes encode cell-surface proteins and support the conclusion that the size and number of Als proteins on the C. albicans cell surface vary with strain and growth conditions.

Hoyer, L. L.; Payne, T. L.; Hecht, J. E.

1998-01-01

78

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

79

Dissimilar metal joining of aluminum alloy to galvanized steel with Al–Si, Al–Cu, Al–Si–Cu and Zn–Al filler wires  

Microsoft Academic Search

Aluminum alloy sheets were lap joined to galvanized steel sheets by gas tungsten arc welding (GTAW) with Al–5% Si, Al–12% Si, Al–6% Cu, Al–10% Si–4% Cu and Zn–15% Al filler wires. Different amounts of Si, Cu and Zn were introduced into the weld through different filler wires. The effects of alloying elements on the microstructure in the weld and tensile

Honggang Dong; Wenjin Hu; Yuping Duan; Xudong Wang; Chuang Dong

80

The effect of Si in Al-alloy on electromigration performance in Al filled vias  

NASA Astrophysics Data System (ADS)

Electromigration performance of vias filled with Al-Si-Cu alloys on Ti glue layers was investigated in comparison with W-stud vias. In Al-Si-Cu filled vias, voids were formed at only a few locations in the test structure, while voids were formed at every via in W-stud via chains. It is supposed that Al moves through the Al-Si-Cu via during electromigration in spite of the existence of a glue layer at the via bottom. This phenomenon was observed only in the vias filled with Al-Si-Cu alloy. Al movement was prohibited in Al-Cu filled vias. In Al-Si-Cu filled vias, an Al-Ti-Si alloy was formed at the via bottom while Al3Ti was formed at Al-Cu filled vias. Al is speculated to move through this Al-Ti-Si alloy during electromigration.

Kageyama, Makiko; Hashimoto, Keiichi; Onoda, Hiroshi

1998-01-01

81

Growth processes in molecular beam expitaxy of single-crystal Al layers on AlAs  

Microsoft Academic Search

The molecular beam epitaxial growth processes of Al single-crystal layers deposited at room temperature on As-stabilized and on Al-stabilized AlAs surfaces are investigated insitu using reflection high-energy electron diffraction (RHEED). The epitaxy relationship of Al with the underlying AlAs is (011)[100]Al\\/\\/(001)[110]AlAs irrespective of the surface stoichiometry of AlAs. Detailed RHEED investigation suggests that the initially deposited two one-monolayer-thick Al layers

Hiroaki Nakahara; Hirofumi Matuhata; Yasumasa Okada; Tateki Kurosu; Masamori Iida; Takafumi Yao

1991-01-01

82

Ion beam mixing in the Al\\/NixAl1 - x\\/Ni system  

Microsoft Academic Search

Thin-film alloy samples of Al\\/NixAl1?x\\/Ni (x=0.75, 0.5, 0.25) were irradiated at room temperature and at 160 °C with 280 and 560 keV Xe ions to a dose of 1.1×1016 Xe ions\\/cm2. The samples were analyzed by Rutherford backscattering spectrometry. In the Al\\/Ni3Al\\/Ni configuration the Ni3Al layer mixes more strongly with Al than with Ni. In the Al\\/NiAl\\/Ni samples, the NiAl

E. Rimini; M. Nastasi; J. Liu; J. C. Barbour; J.-P. Hirvonen; J. W. Mayer

1986-01-01

83

First-principles calculations on Al/AlB 2 interfaces  

NASA Astrophysics Data System (ADS)

The AlB 2 (1 1 1) surfaces and Al (1 1 1)/AlB 2 (0 0 0 1) interface were studied by first-principles calculations to clarify the heterogeneous nucleation potential of ?-Al grains on AlB 2 particles in purity aluminium and hypoeutectic Al-Si alloys. It is demonstrated that the AlB 2 (0 0 0 1) surface models with more than nine atomic layers exhibit bulk-like interior, wherein the interlayer relaxations localized within the top three layers are well converged. The outmost layer of AlB 2 free surface having a preference of metal atom termination is evidenced by surface energy calculations. With Al atoms continuing the natural stacking sequence of bulk AlB 2, Al-Al metallic bonds are formed across interface during the combination of Al atoms with Al-terminated AlB 2 surface. The calculated interfacial energy of the Al/AlB 2 interface is much larger than that between the ?-Al and aluminium melts, elucidating the poor nucleation potency of ?-Al grains on AlB 2 particles from thermodynamic considerations.

Han, Y. F.; Dai, Y. B.; Wang, J.; Shu, D.; Sun, B. D.

2011-06-01

84

Photoemission study of Al adlayers on Mn  

NASA Astrophysics Data System (ADS)

Al overlayers on Mn, studied by photoemission spectroscopy, show a large lowering of the Al 2p core-level binding energy by 0.5 eV at submonolayer (0.1 ML) coverage. The binding energy increases with coverage and reaches the bulk Al value at ?1.3 ML. The Al 2p core-level spectrum exhibits extra components related to the different chemical environment at the interface, which decrease in intensity with increasing Al coverage. The Al related plasmon loss features appear above 1 ML. The present results are explained by a strong Al s,p-Mn 3d hybridization at the submonolayer coverage due to interface alloying, whose influence on the spectra is dominated by metallic bonding in the Al layer as coverage increases. The valence-band spectra demonstrate systematic suppression of Mn 3d-like states and emergence of a parabolic free-electron-like Al density of states.

Dhaka, R. S.; Shukla, A. K.; Horn, K.; Barman, S. R.

2011-12-01

85

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

SciTech Connect

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. [Department of Physics, University of Pune, Pune 411007 (India); Das, A. K. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085 (India)

2011-07-15

86

The strengthening effect of Al 3Ti in high temperature deformation of Al–Al 3Ti composites  

Microsoft Academic Search

A series of Al–Al3Ti composites with systematic variation of Al3Ti content were prepared by mechanical alloying. Microstructural observations have indicated that among these composites, the only distinct variable is the Al3Ti content, while the other microstructural variables are essentially the same. The high temperature (623–773K) deformation behavior of these composites was found to be similar to that of dispersion-hardened aluminum.

S. H. Wang; P. W. Kao

1998-01-01

87

Processing of In-Situ Al-AlN Metal Matrix Composites via Direct Nitridation Method.  

National Technical Information Service (NTIS)

The primary objective of this research was to provide a fundamental understanding of the processing science necessary to fabricate the Aluminum Nitride (AlN) reinforced Aluminum (Al) composites via direct nitration of the Al alloy melt. From the thermodyn...

K. S. Shin Y. S. Kim N. J. Kim

1998-01-01

88

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

89

The preparation and mechanical properties of Al 2O 3\\/Ni 3Al composites  

Microsoft Academic Search

Al2O3\\/Ni3Al composites containing 10vol% of intermetallic phase have been studied in this work. Ni3Al particles with two different morphologies were added to the alumina matrix, viz. Ni3Al as-prepared (AP) by atomization and Ni3Al finely ball-milled (BM) in argon for 96h. Both AP and BM composites were prepared by pressureless sintering at a relatively low temperature. As-prepared Ni3Al powder was also

Vincenzo M Sglavo; Francesco Marino; Bing-Rong Zhang

1999-01-01

90

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

91

Phosphorus Enhances Al Resistance in Al-resistant Lespedeza bicolor but not in Al-sensitive L. cuneata Under Relatively High Al Stress  

PubMed Central

Background and Aims Aluminium (Al) toxicity and phosphorus (P) deficiency often co-exist in acidic soils and limit crop production worldwide. Lespedeza bicolor is a leguminous forage species that grows very well in infertile, acidic soils. The objective of this study was to investigate the effects of Al and P interactions on growth of Lespedeza and the distributions of Al and P in two different Al-resistant species, and to explore whether P can ameliorate the toxic effect of Al in the two species. Methods Two species, Lespedeza bicolor and L. cuneata, were grown for 30 d with alternate Al and P treatments in a hydroponics system. Harvested roots were examined using a root-system scanner, and the contents of Al, P and other nutrient elements in the plants were determined using inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Haematoxylin staining was used to observe the distribution of Al in the roots of seedlings. After pre-culture with or without P application, organic acids in the exudates of roots exposed to Al were held in an anion-exchange resin, eluted with 2 m HCl and then analysed using high-performance liquid chromatography (HPLC). Key Results Lespedeza bicolor exhibited a stronger Al resistance than did L. cuneata; Al exclusion mechanisms may mainly be responsible for resistance. P application alleviated the toxic effect of Al on root growth in L. bicolor, while no obvious effects were observed in L. cuneata. Much less Al was accumulated in roots of L. bicolor than in L. cuneata after P application, and the P contents in both roots and shoots increased much more for L. bicolor than for L. cuneata. Lespedeza bicolor showed a higher P/Al ratio in roots and shoots than did L. cuneata. P application decreased the Al accumulation in root tips of L. bicolor but not in L. cuneata. The amount of Al-induced organic acid (citrate and malate) exudation from roots pre-cultured with P was much less than from roots without P application; no malate and citrate exudation was detected in L. cuneata. Conclusions P enhanced Al resistance in the Al-resistant L. bicolor species but not in the Al-sensitive L. cuneata under relatively high Al stress, although P in L. cuneata might also possess an alleviative potential. Enhancement of Al resistance by P in the resistant species might be associated with its more efficient P accumulation and translocation to shoots and greater Al exclusion from root tips after P application, but not with an increased exudation of organic acids from roots.

Sun, Qing Bin; Shen, Ren Fang; Zhao, Xue Qiang; Chen, Rong Fu; Dong, Xiao Ying

2008-01-01

92

Nonstoichiometry of Al-Zr intermetallic phases.  

National Technical Information Service (NTIS)

Nonstoichiometry of metastable cubic (beta)(prime) and equilibrium tetragonal (beta) Al-Zr intermetallic phases of the nominal composition Al(sub 3)Zr in Al-rich alloys has been extensively studied. It is proposed that the ''dark contrast'' of (beta)(prim...

V. Radmilovic G. Thomas

1994-01-01

93

Rethinking ALS: The FUS about TDP43  

Microsoft Academic Search

Amyotrophic lateral sclerosis (ALS) is an adult-onset neuro- degenerative disorder in which premature loss of motor neu- rons leads to fatal paralysis with a typical disease course of 1 to 5 years. Most forms of ALS are sporadic, but ~10% of patients have an inherited familial form of the disease and a clear family history. Understanding of ALS pathogenesis began

Clotilde Lagier-Tourenne; Don W. Cleveland

2009-01-01

94

Correlation between Al2O3 particles and interface of Al Al2O3 coatings by cold spray  

NASA Astrophysics Data System (ADS)

Al Al2O3 composite coatings with different Al2O3 particle shapes were prepared on Si and Al substrate by cold spray. The powder compositions of metal (Al) and ceramic (Al2O3) having different sizes and agglomerations were varied into ratios of 10:1 wt% and 1:1 wt%. Al2O3 particles were successfully incorporated into the soft metal matrix of Al. It was found that crater formation between the coatings and substrate, which is typical characteristic signature of cold spray could be affected by initial starting Al2O3 particles. In addition, when the large hard particles of fused Al2O3 were employed, the deep and big craters were generated at the interface between coatings and hard substrates. In the case of pure soft metal coating such as Al on hard substrate, it is very hard to get proper adhesion due to lack of crater formation. Therefore, the composite coating would have certain advantages.

Lee, Ha Yong; Jung, Se Hun; Lee, Soo Yong; You, Young Ho; Ko, Kyung Hyun

2005-12-01

95

Nanoscale interaction layer at the interface between Al films and SiO2 substrates of Al/AlOx/Al Josephson tunnel junctions  

NASA Astrophysics Data System (ADS)

An interaction layer is found at the Al/SiO2 interface in Al/AlOx/Al tunnel junctions grown on SiO2 substrates. The amorphous intermixing layer has an average thickness of about 5 nm. We present the detailed structure of this interfacial layer as determined by transmission electron microscopy. The layer contains alumina with aluminum being octahedrally coordinated according to electron energy loss spectroscopy analysis rather than tetrahedrally coordinated, where the latter coordination is the most common type in amorphous alumina. Depth profiles of the Al-O and Si-O bonding characteristics were also investigated using energy loss near edge structure.

Zeng, L. J.; Greibe, T.; Nik, S.; Wilson, C. M.; Delsing, P.; Olsson, E.

2013-04-01

96

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

97

A Thermodynamic Description of the Al-Cr-Si System  

Microsoft Academic Search

The Al-Cr-Si system was critically assessed using the CALPHAD technique. The solution phases (liquid, bcc, fcc, and diamond)\\u000a were described by a substitutional solution model. The compounds CrSi2, Cr3Si, AlCr2, ?Al8Cr5, ?Al8Cr5, Al4Cr, and Al11Cr2 in the Al-Cr-Si system were treated with sublattice models (Cr, Si)(Al, Cr, Si)2, (Cr, Si)3(Al, Cr, Si), (Al, Cr, Si)(Al, Cr)2, ?(Al, Cr, Si)8(Al, Cr,

Yu Liang; Cuiping Guo; Changrong Li; Zhenmin Du

2009-01-01

98

High-temperature tribological properties of CrAlN, CrAlSiN and AlCrSiN coatings  

Microsoft Academic Search

Cr–Al–Si–N coatings with high and low Cr\\/Al ratios (CrAlSiN and AlCrSiN, respectively) were deposited on WC substrates by cathodic arc and compared with a reference Cr–Al–N coating. The silicon content was close to 3at.%. X-ray diffraction analysis showed that CrAlN and CrAlSiN coatings exhibited the cubic Cr(Al)N structure, whereas in AlCrSiN a mixture of cubic Cr(Al)N and wurtzite-type AlN was

Tomas Polcar; Albano Cavaleiro

2011-01-01

99

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

100

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

2013-10-01

101

Nucleation and Precipitation Strengthening in Dilute Al-Ti and Al-Zr Alloys  

NASA Astrophysics Data System (ADS)

Two conventionally solidified Al-0.2Ti alloys (with 0.18 and 0.22 at. pct Ti) exhibit no hardening after aging up to 3200 hours at 375 °C or 425 °C. This is due to the absence of Al3Ti precipitation, as confirmed by electron microscopy and electrical conductivity measurements. By contrast, an Al-0.2Zr alloy (with 0.19 at. pct Zr) displays strong age hardening at both temperatures due to precipitation of Al3Zr (L12) within Zr-enriched dendritic regions. This discrepancy between the two alloys is explained within the context of the equilibrium phase diagrams: (1) the disparity in solid and liquid solubilities of Ti in ?-Al is much greater than that of Zr in ?-Al; and (2) the relatively small liquid solubility of Ti in ?-Al limits the amount of solute retained in solid solution during solidification, while the comparatively high solid solubility reduces the supersaturation effecting precipitation during post-solidification aging. The lattice parameter mismatch of Al3Ti (L12) with ?-Al is also larger than that of Al3Zr (L12), further hindering nucleation of Al3Ti. Classical nucleation theory indicates that the minimum solute supersaturation required to overcome the elastic strain energy of Al3Ti nuclei cannot be obtained during conventional solidification of Al-Ti alloys (unlike for Al-Zr alloys), thus explaining the absence of Al3Ti precipitation and the presence of Al3Zr precipitation.

Knipling, Keith E.; Dunand, David C.; Seidman, David N.

2007-10-01

102

Conversion of Al 13 Keggin ? into Al 30: a reaction controlled by aluminum monomers  

Microsoft Academic Search

In situ 27Al NMR experiments under hydrothermal and room temperature conditions demonstrate that aluminum monomers are the species controlling the Al13 Keggin ? conversion into Al30. New 27Al NMR signatures of Keggin-type aluminum polycation are observed in solution. A chemical pathway is proposed to explain the isomerization process.

Lionel Allouche; Francis Taulelle

2003-01-01

103

A surface-potential-based model for AlGaN/AlN/GaN HEMT  

NASA Astrophysics Data System (ADS)

A new surface-potential-based model for AlGaN/AlN/GaN high electron mobility transistor (HEMT) is proposed in this paper. Since the high polarization effects caused by AlN interlayer favorably influence the two dimensional electron gas (2DEG) and scattering mechanisms, we first add spontaneous and piezoelectric charge terms to the source equation of surface-potential, and a mobility model for AlGaN/AlN/GaN HEMT is rewritten. Compared with TCAD simulations, the DC characteristics of AlGaN/AlN/GaN HEMT are faithfully reproduced by the new model.

Jie, Wang; Lingling, Sun; Jun, Liu; Mingzhu, Zhou

2013-09-01

104

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

105

Effect of native Al 2O 3 on the elastic response of nanoscale Al films  

Microsoft Academic Search

A continuous, dense aluminum oxide (Al2O3) layer of about 5 nm forms on the surface of Al upon exposure to oxygen or dry air. Since the elastic moduli of Al and Al2O3 are 69 GPa and 370 GPa, respectively, the elastic modulus of a thin Al film of sub-micron dimension (with the native oxide layer) should be much higher than

M. T. A. Saif; S. Zhang; A. Haque; K. J. Hsia

2002-01-01

106

Effect of thermomechanical treatment on the properties of Fe11Al and Fe14Al alloys  

Microsoft Academic Search

Fe-Al alloys have the potential to be relatively inexpensive soft magnetic materials if their formability could be improved. An investigation has been made on the effect of thermomechanical treatment on the properties of Fe-11 wt%Al and Fe-14 wt%Al alloys (designated Fe-11Al and Fe-14Al respectively). For the former the room temperature mechanical properties were found to be determined principally by the

Syahril; R. D. Rawlings

2002-01-01

107

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

NASA Astrophysics Data System (ADS)

Atom probe tomography was used to characterize AlN interlayers in AlGaN/AlN/GaN heterostructures grown by plasma-assisted molecular beam epitaxy (PAMBE), NH3-based molecular beam epitaxy (NH3-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 NH3-MBE and MOCVD were ~85% and ~47%, respectively. Hall measurements were performed to determine the two-dimensional electron gas mobility and sheet concentration. Sheet concentrations were ~25%-45% higher with molecular beam epitaxy than with MOCVD, and these results matched well with atom probe data.

Mazumder, Baishakhi; Kaun, Stephen W.; Lu, Jing; Keller, Stacia; Mishra, Umesh K.; Speck, James S.

2013-03-01

108

Development of Al2O3 fiber-reinforced Al2O3-based ceramics.  

PubMed

The purpose of this study was to use a tape casting technique to develop an Al2O3 fiber-reinforced Al2O3-based ceramic material (Al2O3-fiber/Al2O3 composite) into a new type of dental ceramic. The Al2O3-based ceramic used a matrix consisting of 60 wt% Al2O3 powder and 40 wt% SiO2-B2O3 powder. The prepreg sheets of Al2O3-fiber/Al2O3 composite (in which uniaxially aligned Al2O3 fibers were infiltrated with the Al2O3-based matrix) were fabricated continuously using tape casting technique with a doctor blade system. Multilayer preforms of Al2O3-fiber/Al2O3 composite sheets were then sintered at a maximum temperature of 1000 degrees C under an atmospheric pressure in a furnace. The results showed that the shrinkage and bending properties of Al2O3-fiber/Al2O3 composite exceeded those of unreinforced Al2O3--hence demonstrating the positive effects of fiber reinforcement. In conclusion, the tape casting technique has been utilized to successfully develop a new type of dental ceramic material. PMID:15510857

Tanimoto, Yasuhiro; Nemoto, Kimiya

2004-09-01

109

Contribution of interface capacitance to the electric-field breakdown in thin-film Al-AlOx-Al capacitors  

NASA Astrophysics Data System (ADS)

We present a systematic study of the dependence of breakdown voltages on oxide thickness d in Al-AlOx-Al thin-film capacitor structures. For sufficiently thin dielectrics, we find that a significant portion of the measured breakdown potential Vb occurs across the electrode interfaces, thereby leading to an overestimate (Vb/d) of the true breakdown electric field Eb across the dielectric. By modeling this interface contribution as an ``interface'' capacitance in series with the geometric ``bulk'' capacitance, we find for high-quality rf magnetron-sputtered AlOx dielectrics that Eb is independent of d over the range 30-300 Å.

Singh-Bhalla, Guneeta; Du, Xu; Hebard, Arthur F.

2003-09-01

110

Reply to Vance et al.  

SciTech Connect

In our report of a family with a motor and sensory polyneuropathy that was linked to chromosome 3q, we classified this neuropathy as a form of hereditary motor and sensory neuropathy II (HMSN II, also known as {open_quotes}CMT2{close_quotes}). Doubts have been raised by Vance et al. as to whether this neuropathy should be classified as hereditary sensory autonomic neuropathy I (HSAN I) instead of HMSN II. While it is reasonable to raise such doubts, we believe that the neuropathy is best designated as HMSN II for the reasons described below. The group of disorders described as HSAN are characterized by primary or predominant involvement of sensory and autonomic neurons that fail to develop or that undergo atrophy and degeneration. These disorders were extensively reviewed by Dyck and Ohta, who initially described them as the hereditary sensory neuropathies (HSN). It was Dyck who subsequently suggested that these disorders be designated HSAN rather than HSN, because of the presence of autonomic involvement. 8 refs.

Woon-Chee Yee; Elliott, J.L; Kwon, J.M.; Goodfellow, P. [Washington Univ. School of Medicine, St. Louis, MO (United States)

1996-07-01

111

Una aproximación didáctica al Guernica de Picasso  

Microsoft Academic Search

L’article presenta una aproximació al Guernica, de Pablo Picasso, mitjançant l’anàlisi de les seves possibilitats per a l’estudi de la pintura i de la relació entre la creació i el coneixement de la Història de l’Art. Al mateix temps, es presenta un model de treball que s’inicia amb una mirada als problemes derivats de l’observació per tal d’assolir la interpretació

Antonia Fernández Valencia

2003-01-01

112

Structure of amorphous Al2O3  

NASA Astrophysics Data System (ADS)

The structure of amorphous Al2O3 samples, prepared by anodic oxidation of aluminium foils, was investigated by X-ray and neutron diffraction. The partial pair correlation functions were determined from computer simulation of the structure using the Reverse Monte Carlo method with the result that amorphous Al2O3 is built up by AlO4 tetrahedra with corner sharing oxygen atoms. Pores in the material were characterized by neutron small-angle scattering.

Lamparter, P.; Kniep, R.

1997-02-01

113

DZ Bank als Integrator im Netzwerk  

Microsoft Academic Search

Die DZ Bank mit Hauptsitz Frankfurt am Main wurde 1883 als Landwirtschaftliche Genossenschaftsbank der hessischen Darlehnskassenvereine\\u000a gegründet. Aus zahlreichen Fusionen und Übernahmen ist die viertgrösste deutsche Bank, die heutige DZ Bank AG, entstanden.\\u000a Innerhalb des deutschen genossenschaftlichen Bankensektors, auch Finanzverbund genannt, fungiert die DZ Bank AG (s. Bild 11-1)\\u000a als eines von zwei Zentralinstituten für mehr als 1.000 Genossenschaftsbanken mit

Jens Wolf; Falk Kohlmann

114

Interpretation of 26Al in Meteoritic Inclusions  

Microsoft Academic Search

We suggest that the large 26Al\\/27Al = 5 x 10-5 abundance ratio found in calcium-aluminum--rich inclusions (CAIs) in meteorites is produced by energetic particle irradiation in the early solar system but only in a thin (0.2 g cm-2) skin of the solar preplanetary disk that stops the energetic particles. Buildup of that 26Al concentration happens only during the quiescent, or

Donald D. Clayton; Liping Jin

1995-01-01

115

AL-QAEDA AND WESTERN ISLAM  

Microsoft Academic Search

The terrorism of Al-Qaeda could gravely endanger social co-existence in western countries with large Islamic communities. Al-Qaeda uses the presence of Muslims in Europe and the United States in order to hide itself, recruit new members and obtain aid. Even though the majority of the Muslims who live in the West reject terrorism, there exists proof that Al-Qaeda has managed

Javier Jordan; Luisa Boix

2004-01-01

116

al-Qaeda: An Agile Enterprise  

Microsoft Academic Search

This paper describes the preliminary results of efforts to use soft systems thinking and analy- sis to better understand the agility of the al-Qaeda network. The application of systems tools to a social phenomenon has led to insights on what makes the al-Qaeda extended enterprise agile. Examining the response ability of elements which allow al-Qaeda to recover and restore opera-

Nicole Long; Trina Powell Richard Fekecs; Paul Petersen; Vicente Tur-Rojas; Art Pyster

2008-01-01

117

Photoionization spectroscopy of LiAl  

NASA Astrophysics Data System (ADS)

An electronic spectrum is observed for the new heteronuclear metal dimer, LiAl. This dimer is produced by laser vaporization of an alloy metal sample in a pulsed nozzle cluster source. Resonant two-photon photoionization (R2PI) is employed to collect this spectrum. We observe and characterize two excited electronic states for both the (6)Li-Al and (7)Li-Al isotopes. The analysis of hotbands provides the vibrational frequency (318.3/cm) and dissociation energy (0.75 eV) for the LiAl ground state, which both agree well with the predictions of ab initio theory.

Brock, L. R.; Pilgrim, J. S.; Duncan, M. A.

1994-11-01

118

Thalidomide causes sinus bradycardia in ALS  

Microsoft Academic Search

Objective\\u000a   Neuroinflammation contributes to motor neuron degeneration in ALS. Thalidomide (THL) shows potent anti-inflammatory properties\\u000a and increased the lifespan in ALS transgenic mice. Thalidomide was therefore suggested as atherapeutic intervention for the\\u000a treatment of ALS.We conducted a pilot, randomized clinical trial of THL in patients with ALS to assess safety, feasibility,\\u000a and preliminary estimates of treatment efficacy.\\u000a \\u000a \\u000a \\u000a \\u000a Methods\\u000a   Patients were

Thomas Meyer; André Maier; Nadja Borisow; Jörn S. Dullinger; G. Splettstößer; S. Ohlraun; C. Münch; P. Linke

2008-01-01

119

Crack growth resistance ( R-curve) behaviour and thermo-physical properties of Al 2O 3 particle-reinforced AlN\\/Al matrix composites  

Microsoft Academic Search

Crack growth resistance behaviour and thermo-physical properties of Al2O3 particle-reinforced AlN\\/Al matrix composites have been studied as a function of AlN volume fraction as well as Al2O3 particle size. The fracture toughness of the composites decreased with increase in vol% AlN and decrease in Al2O3 particle size. All the composites exhibited R-curve behaviour which has been attributed to crack bridging

Srinivasa Rao Boddapati; Jürgen Rödel; Vikram Jayaram

2007-01-01

120

High temperature properties of CrAlN, CrAlSiN and AlCrSiN coatings – Structure and oxidation  

Microsoft Academic Search

CrAlN, CrAlSiN and AlCrSiN coatings were deposited by cathodic arc deposition technique from composite targets. Three targets were used: (i) Cr\\/Al ratio close to 1, (ii) Cr\\/Al ratio close to 1 with Si addition, and (iii) Cr\\/Al ratio close to 1\\/2 and Si addition. Nitrogen flow was kept constant during the depositions. The Cr\\/Al ratio of the films, measured by

Tomas Polcar; Albano Cavaleiro

2011-01-01

121

Al2Ti precipitation in Al64Fe8Ti28 alloy  

NASA Astrophysics Data System (ADS)

Precipitates of Al2Ti with three different stacking sequences have been observed in Fe-modified Ll2-type ordered Al3Ti specimens. Two of the stacking sequences have been observed previously. The third type of Al2Ti, Al2TiIII, is identified in this study using conventional and highresolution transmission electron microscopy (TEM). The Al2Ti precipitates form as plates along {100} planes and compression tests performed at liquid N temperature show microcracks occurring along those {100} planes. The Al2Ti phase is believed to be responsible for the low cleavage strength that is observed.

Yang, T. Y.; Goo, E.

1994-04-01

122

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

123

Deletion of ALS5, ALS6 or ALS7 increases adhesion of Candida albicans to human vascular endothelial and buccal epithelial cells  

PubMed Central

Summary C. albicans yeast forms deleted for ALS5, ALS6 or ALS7 are more adherent than a relevant control strain to human vascular endothelial cell monolayers and buccal epithelial cells. In the buccal and vaginal reconstituted human epithelium (RHE) disease models, however, mutant and control strains caused a similar degree of tissue destruction. Deletion of ALS5 or ALS6 significantly slowed growth of the mutant strain; this phenotype was not affected by addition of excess uridine to the culture medium. These studies demonstrate similar phenotypic characteristics for the als5?/als5?, als6?/als6? and als7?/als7? strains that are not observed in any of the other C. albicans als?/als? strains.

ZHAO, XIAOMIN; OH, SOON-HWAN; HOYER, LOIS L.

2009-01-01

124

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

125

The Contours of Al Qaeda's Media Strategy  

Microsoft Academic Search

Al Qaeda has crafted a successful media strategy that is adeptly suited for the war of ideas against the United States. Osama bin Laden and Ayman al-Zawahiri have demonstrated a great ability to lead plural groups and exploit innovation with the use of technology. This article explores how they have connected with diverse audiences around the world with a constant

Carl J. Ciovacco

2009-01-01

126

Half Life of exp 26 Al.  

National Technical Information Service (NTIS)

The half-life of exp 26 Al has been redetermined because of suggestions of an error in the accepted value based on its use in calculating exp 21 Ne production rates from cosmic rays in meteorites. Two solutions of exp 26 Al were analyzed for the specific ...

T. L. Norris A. J. Gancarz D. J. Rokop K. W. Thomas

1983-01-01

127

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

128

Diana Al-Hadid: Identity and Heritage  

ERIC Educational Resources Information Center

|Diana Al-Hadid's sculptures reflect the many locations, cultures, histories, and mythologies that have shaped her as an artist. In large-scale works which have the appearance of architectural ruins, Al-Hadid employs imagery drawn from many diverse interests including science and technology, history, and literature. She also incorporates images…

Jungerberg, Tom; Smith, Anna; Borsh, Colleen

2012-01-01

129

Future of Al Qa'ida.  

National Technical Information Service (NTIS)

The death of Osama bin Laden has triggered a re-evaluation of al Qa'ida and its threat to the United States. Some have argued that al Qa'ida will become increasingly irrelevant. 'Between the Arab Spring and the death of bin Laden, it is hard to imagine gr...

S. G. Jones

2011-01-01

130

Al Qaeda: Profile and Threat Assessment.  

National Technical Information Service (NTIS)

There is no consensus among experts in and outside the U.S. Government about the magnitude of the threat to U.S. national interests posed by the Al Qaeda organization. Experts agree that Al Qaeda and its sympathizers intend to conduct major attacks in the...

K. Katzman

2005-01-01

131

Secondary recrystallisation in magnox AL 80  

Microsoft Academic Search

Exaggerated grain growth observed in the magnesium canning alloy Magnox ; AL 80 (Al\\/0.8 wt%, Be\\/0.004 wt%) is typical of the phenomenon classified as ; Secondary Recrystallization. Studies on alloys of varying composition indicate ; that the presence of 40 ppm beryllium is of particular importance in promoting ; the effect. Metallographic observations indicate that both marked equilibrium ; segregation

G. Higgins

1963-01-01

132

Crack growth resistance and strength of the B2 iron aluminides Fe-40Al, Fe-45Al, and Fe-10Ni-40Al (at. %).  

National Technical Information Service (NTIS)

The crack growth resistance and yield strength of the B2 iron aluminides Fe-40Al, Fe-45Al, are Fe-10Ni-40Al (at. %) have been investigated at room temperature laboratory air. After fast cooling from 1273 K, Fe-45Al and Fe-10Ni-40Al are much stronger than ...

J. H. Schneibel P. J. Maziasz

1994-01-01

133

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

2013-07-25

134

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

135

The tensile properties of hot-rolled (Al 2O 3) pAl composites  

Microsoft Academic Search

Hot rolling was carried out on the extruded Al alloy 6061 composite reinforced with Al2O3 particulates ((Al2O3)p-Al composite) along a direction perpendicular to the extrusion direction of the composite. Room-temperature tensile tests of the hot-rolled composites showed a significant increase in strength and fracture strain along the transverse (rolling) direction with increasing reduction in rolling. However, the same properties along

J. C. Lee; K. N. Subramanian

1995-01-01

136

Young's modulus of cold- and hot-rolled (Al 2 O 3 ) p Al composite  

Microsoft Academic Search

The Young's modulus of hot-rolled Al alloy reinforced with Al2O3 particulates, (Al2O3)p-Al composite, is measured using the dynamic sonic resonance test method. The variation in the moduli of cold- and hot-rolled composites, as a function of the reduction ratio, is compared. Although both cold and hot rolling result in more uniform distribution of the particulates, hot rolling causes less damage

J. C. Lee; K. N. Subramanian

1994-01-01

137

Assessment of isotopically exchangeable Al in soil materials using 26Al tracer  

NASA Astrophysics Data System (ADS)

The solubility of aluminium (Al) in many acidic soils is controlled by complexation reactions with soil organic matter. In such soils, Al solubility is theoretically a function of the pool size of "active" Al, i.e., the total amount of Al that equilibrates with the soil solution within a defined period of time. To date, no reliable measurements of "active" Al in soil materials exist. In this study, we determined the isotopically exchangeable pool of Al ( EAl) as an operationally defined assessment of "active" Al in acidic mineral soils. The suitability of CuCl 2 and pyrophosphate (Na 4P 2O 7) as extractants for "active" Al was also evaluated. Eleven samples, mostly from spodic B horizons, were spiked with carrier-free 26Al and equilibrated for different time periods (1-756 h). The size of the Al pool with which the 26Al tracer exchanged increased with time during the whole experimental period. Thus, contact time between solid and solution phases needs to be defined when assessing the "active" Al pool. Values of EAl obtained after 1 to 5 d of equilibration were equal to the amount of CuCl 2 extractable Al, but considerably smaller than the Na 4P 2O 7-extractable pool. Equilibration times greater than 5 d resulted in CuCl 2 extractable Al concentrations that under-estimated the "active" Al pool. Three of the investigated samples were rich in imogolite-type materials (ITM). In these samples, 30-50 % of the added 26Al rapidly became associated with soil constituents in forms that could not be extracted by Na 4P 2O 7, indicating that a part of ITM may be in a dynamic state.

Kleja, D. Berggren; Standring, W.; Oughton, D. H.; Gustafsson, J.-P.; Fifield, K.; Fraser, A. R.

2005-11-01

138

Widely tunable Fabry-Perot filter using Ga(Al)As-AlOx deformable mirrors  

Microsoft Academic Search

A microelectromechanically tunable Fabry-Perot (FP) microinterferometer is demonstrated using Ga(Al)As-AlOx DBR micromirrors separated by an air gap. The broad-spectral response of Ga(Al)As-AlOx distributed Bragg reflector (DBR) micromirrors allows 3-dB bandwidth of the cavity to remain narrow and stable over the tuning range. Two devices with different number of mirror structures were demonstrated exhibiting linewidths of 0.5 and 2.0 nm, tuning

P. Tayebati; P. D. Wang; D. Vakhshoori; Robert N. Sacks

1998-01-01

139

Formation and properties of Al composites reinforced by quasicrystalline AlCuFeB particles  

Microsoft Academic Search

Al-based composites reinforced by icosahedral (i-) Al59Cu25.5Fe12.5B3 quasicrystalline particles were prepared by solid-state sintering. It was found that Al diffusion from the matrix to the quasicrystalline particles induces phase transformation into the ?-Al7Cu2Fe tetragonal phase. In order to preserve the i phase, we used an oxidation pre-treatment of the particles and studied its influence on the kinetics of the phase

S. Kenzari; P. Weisbecker; M. Curulla; G. Geandier; V. Fournee; J. M. Dubois

2008-01-01

140

Selenium adsorption on Mg–Al and Zn–Al layered double hydroxides  

Microsoft Academic Search

Layered double hydroxides (LDHs) have high anion exchange capacities that enhances their potential to remove anionic contaminants from aqueous systems. In this study, different Mg–Al and Zn–Al LDHs were synthesized by a coprecipitation method, with the products evaluated for their ability to adsorb selenite (SeO32?) and selenate (SeO42?). Results indicated the adsorption isotherm for SeO32? retention by Mg–Al and Zn–Al

Youwen You; George F Vance; Hongting Zhao

2001-01-01

141

Wet oxidation of AlGaAs vs. AlAs: A little gallium is good  

Microsoft Academic Search

In summary, buried oxides formed from the wet oxidation of AlGaAs alloys, rather than AlAs, are found to be superior in terms of oxidation isotropy, mechanical stability, and strain. It is not surprising that VCSELs using AlGaAs oxide layers as current apertures have shown promising reliability as compared to VCSELs using AlAs layers. Comparisons of lifetime data for VCSELs with

Kent D. Choquette; K. M. Geib; Robert Hull; H. Q. Hou; K. L. Lear; H. C. Chuia; B. E. Hammons; J. A. Nevers

1996-01-01

142

Al-MCM-41 sorbents for bovine serum albumin: relation between Al content and performance  

Microsoft Academic Search

The adsorption of bovine serum albumin (BSA) onto Al-MCM-41 samples with different Si\\/Al ratio and pore width about 36Å was studied. It is shown that the adsorption capacity of Al-MCM-41 increased with decreasing of the Si\\/Al ratio, probably due to the increased affinity of BSA for the external surface of the adsorbents. The materials synthesized are agglomerates of primary particles,

Lei Ji; Amit Katiyar; Neville G. Pinto; Mietek Jaroniec; Panagiotis G. Smirniotis

2004-01-01

143

Properties of Sintered Al Substituted NdFeB Magnets  

NASA Astrophysics Data System (ADS)

The effect of partial substitution of Fe by Al (Al, Al2O3) on the magnetic properties and the corrosion resistance of the sintered NdFeB magnet has been investigated. With the increasing amount of Al, the anisotropy field and the saturation magnetization decrease, but the coercivity increases up to 4 at.% Al and further alloying of Al leads to a decrease of the coercivity. Different substances like Al (metallic Al or Al2O3) modify the microstructure to different increase in the coercivity and especially to changes in the remanence. Alloying Al via metallic Al decreases the remanence, whereas via Al2O3) up to 4 at.%0 Al increases it. The Al additions inhibit atmospheric corrosion of the magnet. We have found that Al2O3 in sintered NdFeB magnet substantially improves the coercivity and the corrosion resistance with the improved remanence.

Szymura, S.; Bala, H.; Rabinovich, Yu. M.; Wiechu?a, J.

144

EFFECT OF AL PARTICLE SIZE ON THE THERMAL DEGRADATION OF AL\\/TEFLON MIXTURES  

Microsoft Academic Search

Reactive mixtures of aluminum (Al) and polytetrafluoroethylene (PTFE or Teflon) have applications in propellants, explosives, and pyrotechnics. This study examines the thermal degradation behavior of Teflon and nanometer scale Al particles compared with micron-scale Al particles. Differential scanning calorimetry and thermo-gravimetric analyses were performed in an argon environment on both nanometer and micron scale particulate mixtures revealing lower ignition temperatures

DUSTIN T. OSBORNE; MICHELLE L. PANTOYA

2007-01-01

145

Cyclic Oxidation of FeCrAlY/Al2O3 Composites.  

National Technical Information Service (NTIS)

Three-ply FeCrAlY/Al2O3 composites and FeCrAlY matrix-only samples were cyclically oxidized at 1000 C and 1100 C for up to 1000 1-hr cycles. Fiber ends were exposed at the ends of the composite samples. Following cyclic oxidation, cracks running parallel ...

J. A. Nesbitt S. L. Draper C. A. Barrett

1999-01-01

146

Precipitation kinetics in Al6061 and in an Al6061-alumina particle composite  

Microsoft Academic Search

Differential scanning calorimetry (DSC) was used to study the precipitation kinetics of metastable phases in an Al6061 alloy and a 20 vol % alumina particle reinforced Al6061 composite. The thermal effects in the DSC traces were analysed quantitatively. The kinetic parameters for the phase transformations in the Al6061 alloy and composite were calculated using the varying heating rate method and

S. P. Chen; K. M. Mussert; S. van der Zwaag

1998-01-01

147

Water Quality and Planktonic Communities in Al-Khadoud Spring, Al-Hassa,Saudi Arabia  

Microsoft Academic Search

Problem statement: Al-Khadoud spring is one of the most important wat er resources in Al- Hassa Governorate, Saudi Arabia. However, much of its biotic information is still unknown. This study presented preliminary ecological information of thi s aquatic body. The aim of this research was to study the water characteristics and the planktonic organisms inhibiting Al-Khadoud spring and its irrigational

Adel A. Fathi; Mohammed A. Al-Kahtani

2009-01-01

148

Fabrication, phase transformation studies and characterization of SiC-AlN-Al2OC ceramics. Progress report.  

National Technical Information Service (NTIS)

The research effort conducted to date had two specific objectives: (1) to determine phase relations and phase transformations in SiC-AlN, AlN-Al(sub 2)OC, and SiC-Al(sub 2)OC pseudobinary systems and in SiC-AlN-Al(sub 2)OC pseudoternary system, and (2) to...

A. V. Virkar

1990-01-01

149

Al?Al 3Ni eutectic alloy and AL/WC(NI) composite directionally solidified under microgravity and normal gravity  

NASA Astrophysics Data System (ADS)

Directional solidification of Al?Al 3Ni eutectic alloy and Al/WC(Ni) composite were performed in the Multi-functional Crystal Growing Furnace on board the unmanned Chinese Shenzhou II spacecraft and on the ground respectively. The microstructures of the samples were investigated applying metallographic, SEM, XRD and image analysis techniques. Many differences were found between the space samples and the ground samples. It could be concluded that gravity condition had a strong influence on the solidification behavior of materials. The temperature gradient driven convection, i.e. Marangoni Convection, played an apparent role on the formation of solidification microstructure under microgravity.

Luo, X.-H.; Huang, Q.; Liu, B.-D.; Zhang, X.-M.; Li, Y.-Y.

2003-07-01

150

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

151

A new discontinuously reinforced aluminum MMC: Al+AlB{sub 2} flakes  

SciTech Connect

Development of a novel metal matrix composite based on the Al-B alloy system has been undertaken. Preparation of this discontinuously reinforced material is based on the precipitation of high aspect ratio AlB{sub 2} from an Al-B alloy. This paper describes a number of efforts forced on preparing high volume fractions (> 30 v%) of AlB{sub 2} in aluminum. New insights into the behavior of the Al-B alloys system allowed this effort to be successful.

HALL,AARON C.; ECONOMY,J.

2000-06-08

152

Thermal conductivity of ?-Al2O3 and ?-Al2O3 wear-resistant coatings  

NASA Astrophysics Data System (ADS)

The thermal conductivities of ?-Al2O3 and ?-Al2O3 wear-resistant coatings are measured using the 3? method in the temperature range 80Al2O3 coating has a thermal conductivity comparable to sapphire at T>300 K. The relatively small thermal conductivity of ?-Al2O3, a factor of ~3 smaller than ?-Al2O3, suggests that this metastable phase of alumina can be applied as an effective thermal barrier for cutting tools.

Cahill, David G.; Lee, S.-M.; Selinder, Torbjörn I.

1998-06-01

153

Extended Al(Mn) solution in a rapidly solidified Al-Li-Mn-Zr alloy  

SciTech Connect

This paper reports the effect of coolingrate on the extension of Mn solid solubility in Al and on the relative amount of MnAl (MnAl{sub 6} and MnAl{sub 4}) secondary phases during gas atomization and spray deposition critically examined. An alloy of composition Al-6.5Mn-2.3Li-0.65Zr (wt pct) currently being investigated for applications requiring high strength and low density at high temperatures was selected for this study. The material was exposed to various solidification histories by altering gas pressure and powder size during solidification.

Ruhr, M.; Baram, J.C. (Materials Engineering Dept., Ben-Gurion Univ. of the Negev, Beer-Sheeva (IL)); Lavernia, E.J. (Materials Section, Mechanical Engineering Dept., Univ. of California, Irvine, CA (US))

1990-06-01

154

Phase stability and microstructure of Al-Ti-Fe near Al3Ti  

NASA Astrophysics Data System (ADS)

The phase stability and microstructure of Al-Ti-Fe near Al3Ti at 800 °C are studied by using high resolution electron microscopy and backscattered electron imaging. One of the most significant changes resulting from the addition of small amounts of iron in this system is to convert tetragonal Al3Ti or Al2Ti into cubic Ll2 structures. In addition, the added iron can change the stacking structure of Al2Ti and the domain size of the long-period one-dimensional antiphase domain structures. A partial ternary phase diagram in this region is also determined.

Yang, T. Y.; Goo, Edward

1995-05-01

155

Phase composition and recrystallization of Al-based Al-Sc-Mn-Zr alloys  

NASA Astrophysics Data System (ADS)

The phase composition and recrystallization of Al-based alloys with small amounts (up to 4 wt %) of transition metals, such as Sc, Mn, and Zr, are studied by metallography and electrical resistivity and hardness measurements. No new phases, besides phases in equilibrium with an Al-based solid solution in the associated ternary systems, are found for the portion of the quaternary Al-Sc-Mn-Zr system under study. It is also found that the manganese and zirconium solubilities in the Al-based solid solution decrease in the presence of scandium and that zirconium additions in Al-Sc-Mn alloys increase their recrystallization temperature.

Rokhlin, L. L.; Bochvar, N. R.; Tarytina, I. E.; Leonova, N. P.

2010-03-01

156

Localized AL amyloidosis: A suicidal neoplasm?  

PubMed Central

Although AL amyloidosis usually is a systemic disease, strictly localized AL deposits are not exceptionally rare. Such case reports form a considerable body of published articles. Although both AL amyloidosis types are formed from an N-terminal segment of a monoclonal immunoglobulin light chain, a typical localized AL amyloid differs from the systemic counterpart by the morphological appearance of the amyloid, and presence of clonal plasma cells and of giant cells. In this article it is pointed out that localized AL amyloidosis (‘amyloidoma') represents a true plasma cell neoplasm and not a pseudotumor. The pathogenesis of localized AL amyloidosis may differ from that of the systemic type, a suggestion underlined by the fact that localized AL amyloidosis of kappa type is as common as that of lambda origin, in contrast to the systemic form where lambda chains constitute the overwhelming majority of cases. It is suggested that oligomeric assemblies of the produced immunoglobulin light chain are toxic to plasma cells, which in this way commit suicide.

2012-01-01

157

TAGLIO CESAREO: ANALISI CRITICA DELLE INDICAZIONI  

Microsoft Academic Search

In the last two decades the practice of cesarean section has increased threefold. The aim of this retrospective study is to analize the indications for cesarean section, to evaluate the influence of emergency conditions on the choice of cesarean section and finally to verify its influence on neonatal outcome. Data related to 4762 delieveres, of which 1529 cesarean sections, were

Fabio Gori; Giuseppe Affronti; Laura Cruciani; Alberto Pasqualucci; Gian Carlo; Di Renzo

2006-01-01

158

FRAMEWORK FOR ANALISIS OF AGRARIAN CONTRACTS  

Microsoft Academic Search

This paper incorporates the interdisciplinary New Institutional and Transaction Costs Economics (combining Economics, Organization, Law, Sociology, Behavioral and Political Sciences) and suggests a holistic framework for analysis of agrarian contracts. First, it specifies type and importance of different mechanisms of governance of agrarian activity. Second, it defines the essence, and classifies types and features of agrarian contracts. Next, it identifies

Hrabrin BACHEV

2010-01-01

159

Hot-electron drift velocity in AlGaN/AlN/AlGaN/GaN camelback channel  

NASA Astrophysics Data System (ADS)

Nanosecond pulses were employed to study hot-electron transport in a nominally undoped Al0.33Ga0.67N/AlN/{Al0.1Ga0.9N/GaN} heterostructure where the mobile electrons are spread in a composite {Al0.1Ga0.9/GaN} dual channel exhibiting a camelback electron density profile at high electric fields. The highest velocity of ˜1.6× 107 cm s-1 was obtained at electric field of 160 kV cm-1 in the channel with the electron density of 0.8 × 1013?cm-2 owing to its proximity to the LO-phonon-plasmon resonance.

Ardaravi?ius, L.; Kiprijanovi?, O.; Liberis, J.; Matulionis, A.; Li, X.; Zhang, F.; Wu, M.; Avrutin, V.; Özgür, Ü.; Morkoç, H.

2012-12-01

160

Characterization of different-Al-content AlGaN/GaN heterostructures on sapphire  

NASA Astrophysics Data System (ADS)

Al x Ga1- x N/GaN high-electron-mobility transistor (HEMT) structures with Al composition ranging from x = 0.13 to 0.36 are grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The effects of Al content on crystal quality, surface morphology, optical and electrical characteristics of the AlGaN/GaN heterostructures have been analyzed. Although high Al-content (36%) heterostructure exhibits a distinguished photoluminescence peak related to recombination between the two-dimensional electron gas and photoexcited holes (2DEG-h), its crystal quality and rough surface morphology are poor. 2DEG mobility increases with the Al content up to 26% and then it apparently decreases for high Al-content (36%) AlGaN/GaN heterostructure. The increase of sheet carrier density with the increase of Al content has been observed. A high mobility at room temperature of 2105 cm2/V s with a sheet carrier density of n s = 1.10 × 1013 cm-2, for a 26% Al-content AlGaN/GaN heterostructure has been obtained, which is approaching state-of-the-art for HEMT grown on SiC. Sheet resistance as low as 274 ?/? has also been achieved.

Ding, Guojian; Guo, Liwei; Xing, Zhigang; Chen, Yao; Xu, Peiqiang; Jia, Haiqiang; Zhou, Junming; Chen, Hong

2010-01-01

161

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

162

Annealing effects on Al and Al-Si contacts with 3C-SiC  

NASA Astrophysics Data System (ADS)

Annealing effects on the current-voltage characteristics of Al and Al-Si contacts with n-type and p-type 3C-SiC films, epitaxially grown on Si by chemical vapor deposition, have been investigated. Al electrodes on n-type 3C-SiC show ohmic characteristics stable up to 400 C, but show distinct rectifying characteristics with annealing at 900 C. To the contrary, Al on p-type 3C-SiC clearly changes from non-ohmic into ohmic with annealing at 900 C. Al-Si alloys, which are usually used as ohmic electrodes for p-type SiC, show the same behavior as Al on n-type 3C-SiC. These results suggest the diffused Al atoms to yield a certain p-type layer.

Daimon, H.; Yamanaka, M.; Sakuma, E.; Misawa, S.; Yoshida, S.

1986-07-01

163

High-performance nonvolatile Al/AlOx/CdTe:Sb nanowire memory device  

NASA Astrophysics Data System (ADS)

Here we demonstrate a room temperature processed nonvolatile memory device based on an Al/AlOx/CdTe:Sb nanowire (NW) heterojunction. Electrical analysis shows an echelon hysteresis composed of a high-resistance state (HRS) and a low-resistance state (LRS), which can allow it to write and erase data from the device. The conductance ratio is as high as 106, with a retention time of 3 × 104 s. Moreover, the SET voltages ranged from +6 to +8 V, whilst the RESET voltage ?0 V. In addition, flexible memory nano-devices on PET substrate with comparable switching performance at bending condition were fabricated. XPS analysis of the Al/AlOx/CdTe:Sb NW heterojunction after controlled Ar+ bombardment reveals that this memory behavior is associated with the presence of ultra-thin AlOx film. This Al/AlOx/CdTe:Sb NW heterojunction will open up opportunities for new memory devices with different configurations.

Xie, Chao; Nie, Biao; Zhu, Long; Zeng, Long-Hui; Yu, Yong-Qiang; Wang, Xian-He; Fang, Qun-Ling; Luo, Lin-Bao; Wu, Yu-Cheng

2013-09-01

164

Transition element modifications of Al-Li  

SciTech Connect

The development of aluminum-lithium metallurgy has led to alloys with unsurpassed combinations of density, specific strength, and specific modulus. This paper describes recent advances in the modification of aluminum-lithium binary alloys through additions of the Group IV-A transition metals (titanium, zirconium, and hafnium). These elements lead to a duplex precipitation hardening behavior through the formation of Al3Li and Al3(TM,Li) (TM = transition element) which act as strengthening precipitates. The influence of the duplex structure on deformation mechanisms and the improvement of mechanical properties in these systems is illustrated by using results for the Al-Li-Zr system. 12 references.

Gayle, F.W.; Levoy, N.F.; Vandersande, J.B.

1987-05-01

165

Suspected variables among Al Sufi stars.  

NASA Astrophysics Data System (ADS)

In the tenth century Al Sufi compiled a catalogue of some 1100 stars. J.E. Gore, around 1900, wrote extensively on the magnitudes of these stars. On intercomparing them with a few other catalogues, Gore surmised that some 38 stars appeared to show secular variations. Here all the Al Sufi magnitudes have been compared with numerous additional sources, but smooth secular variations are not substantiated although some stars seem to have undergone comparatively sudden changes after about 1600. About 70 Al Sufi stars are now named or suscpected variable stars, but nearly all with amplitudes under 0.3 V.

Hoffleit, D.

166

Ni{sub 3}Al aluminide alloys  

SciTech Connect

This paper provides a brief review of the recent progress in research and development of Ni{sub 3}Al and its alloys. Emphasis has been placed on understanding low ductility and brittle fracture of Ni{sub 3}Al alloys at ambient and elevated temperatures. Recent studies have resulted in identifying both intrinsic and extrinsic factors governing the fracture behavior of Ni{sub 3}Al alloys. Parallel efforts on alloy design using physical metallurgy principles have led to properties for structural use. Industrial interest in these alloys is high, and examples of industrial involvement in processing and utilization of these alloys are briefly mentioned.

Liu, C.T.

1993-10-01

167

Al-induced faceting of Si(113)  

NASA Astrophysics Data System (ADS)

Adsorption of Al on a Si(113) substrate at elevated temperatures causes a faceting transition of the initially flat surface. The (113) surface decomposes into a quasi-periodic sequence of Al terminated (115)- and (112)-facets. The resulting surface morphology is characterized in-situ by reciprocal space maps obtained with in-situ spot profile analyzing low-energy electron diffraction and ex-situ atomic force microscopy. The periodicity length of the faceted surface increases with adsorption temperature from 7 nm at 650 °C to 80 nm at 800 °C. The stability of the Al terminated Si(112) surface is the driving force for the faceting transition.

Klein, Claudius; Heidmann, Inga; Nabbefeld, Tobias; Speckmann, Moritz; Schmidt, Thomas; Meyer zu Heringdorf, Frank-J.; Falta, Jens; Horn-von Hoegen, Michael

2013-12-01

168

Thermal diffusion in Ni/Al multilayer  

NASA Astrophysics Data System (ADS)

Two Ni/Al multilayers deposited by ion beam sputtering of nominal design [Ni(200A?)/Al(100A?)]×5 and [Ni(50A?)/Al(227A?)]×5 on Si substrates were annealed at 200°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.; Gupta, M.; Basu, S.

2013-02-01

169

Magnetic properties of FeAl2 and Fe2Al5  

NASA Astrophysics Data System (ADS)

We have investigated magnetic properties of the FeAl2 and Fe2Al5 intermetallic compounds. By measuring the zero-field-cooled and field-cooled static (dc) magnetic susceptibilities in low and high magnetic fields, the frequency-dependent (ac) susceptibility, the magnetization versus the magnetic field, and the thermoremanent magnetization time decay, we found that the magnetic structures of FeAl2 and Fe2Al5 are richer than those published so far in the literature. FeAl2 undergoes complex two-step magnetic ordering. At T ? 32 K, a magnetic phase transition (not yet specified) takes place in which a small fraction of the Fe spins participate, whereas at Tf2 ? 12 K, the majority spin fraction undergoes a spin-freezing transition to a spin glass phase. Fe2Al5 undergoes a transition to a spin glass phase at the spin freezing temperature Tf ? 3 K, which was not reported previously. The spin glass phase in Fe2Al5 is “soft” and fragile with respect to the external magnetic field and can only be observed in low magnetic fields below ˜100 Oe. The origins of the spin glass ordering in the FeAl2 and Fe2Al5 phases are randomness and frustration that are present on the Fe sublattices of both compounds. In FeAl2, the Fe spins are positioned randomly on the three mixed-occupation Al/Fe sites of the unit cell, whereas in Fe2Al5, partial occupation of the Fe-neighboring Al2 and Al3 atomic sites imposes different degrees of Fe moment screening by the electron cloud, resulting in a random distribution of the magnetic moment sizes. Geometric frustration because of positioning of the antiferromagnetically coupled Fe spins on triangles is present in both compounds as well.

Jagli?i?, Z.; Vrtnik, S.; Feuerbacher, M.; Dolinšek, J.

2011-06-01

170

Electroforming and Ohmic contacts in Al-Al2O3-Ag diodes  

NASA Astrophysics Data System (ADS)

Electroforming of metal-insulator-metal (MIM) diodes is a non-destructive dielectric breakdown process that changes the diode from its initial high resistance state (HRS) to a low resistance state (LRS). After electroforming, resistance switching memories (RSMs) use voltages to switch from HRS to LRS and back. Many MIM combinations are proposed for use in RSMs. In many cases conduction in the LRS is nearly temperature independent at low temperatures; an Ohmic contact with a barrier to electron injection of ~0 eV results from electroforming. Electroforming of Al-Al2O3-Ag diodes with amorphous anodic Al2O3 thicknesses between 12 and 41 nm has been studied. Two anodizing electrolytes have been used; 0.1 M ammonium pentaborate (bor-H2O) and a solution of 0.1 M of ammonium pentaborate per liter of ethylene glycol (bor-gly). Polarization of Al2O3 and negative charge in Al2O3 are much larger when Al2O3 is formed in bor-H2O solution than when Al is anodized in bor-gly solution. Electroforming of Al-Al2O3-Ag diodes results in an Ohmic contact at the Al-Al2O3 interface, voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) characteristics, electroluminescence (EL), and electron emission into vacuum (EM) from filamentary conducting channels. Two distinct modes of electroforming occur for Al-Al2O3-Ag diodes. ?-forming occurs for 2.5 V <~ VS <~ 5 V, where VS is the applied voltage. It is characterized by an abrupt current jump with the simultaneous appearance of EL and EM. ?-forming occurs for VS >~ 7 V. I-V curves, EL, and EM develop gradually and are smaller than for ?-forming. Electroforming occurs more readily for diodes with Al2O3 formed in bor-H2O that have greater defect densities. Fully developed I-V curves have similar VCNR, EL, and EM after ?-forming or ?-forming. A model is proposed in which excited states of F-centers, oxygen vacancies in amorphous anodic Al2O3, form defect conduction bands. Electroforming that results in an Ohmic contact requires injection of positive charge at the Al-Al2O3 interface. ?-forming is the result of ionization of F-center recombination centers with energies that are close to the Al Fermi level. Hole injection by high-field ionization of valence band states of Al2O3 causes ?-forming.

Hickmott, T. W.

2012-03-01

171

Interdiffusion in Diffusion Couples: U-Mo v. Al and Al-Si  

SciTech Connect

Interdiffusion and microstructural development in the U-Mo-Al system was examined using solid-tosolid diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo and U-12wt.%Mo vs. pure Al, annealed at 600°C for 24 hours. The influence of Si alloying addition (up to 5 wt.%) in Al on the interdiffusion microstructural development was also examined using solid-to-solid diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo and U-12wt.%Mo vs. pure Al, Al-2wt.%Si, and Al-5wt.%Si annealed at 550°C up to 20 hours. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA) were employed to examine the development of a very fine multiphase intermetallic layer. In ternary U-Mo-Al diffusion couples annealed at 600°C for 24 hours, interdiffusion microstructure varied of finely dispersed UAl3, UAl4, U6Mo4Al43, and UMo2Al20 phases while the average composition throughout the interdiffusion zone remained constant at approximately 80 at.% Al. Interdiffusion microstructure observed by SEM/TEM analyses and diffusion paths drawn from concentration profiles determined by EPMA appear to deviate from the assumption of “local thermodynamic equilibrium,” and suggest that interdiffusion occurs via supersaturated UAl4 followed by equilibrium transformation into UAl3, U6Mo4Al43, UAl4 and UMo2Al20 phases. Similar observation was made for U-Mo vs. Al diffusion couples annealed at 550°C. The addition of Si (up to 5 wt.%) in Al significantly reduced the thickness of the intermetallic layer by changing the constituent phases of the interdiffusion zone developed in U-Mo vs. Al-Si diffusion couples. Specifically, the formation of (U,Mo)(Al,Si)3 with relatively large solubility for Mo and Si, along with UMo2Al20 phases was observed along with disappearance of U6Mo4Al43 and UAl4 phases. Simplified understanding based on U-Al, U-Si, and Mo-Si binary phase diagrams is discussed in the light of the beneficial effect of Si alloying addition.

D. D. Keiser, Jr.; E. Perez; B. Yao; Y. H. Sohn

2009-11-01

172

Benefits for Military Veterans with ALS  

MedlinePLUS

... of Veterans More in this section: Visit our Wall of Honor How to Apply for Benefits ... | FAQ | Privacy Policy | Link Policy | RSS | Contact Us The ALS Association - 1275 K Street NW - Suite 250 - Washington, DC 20005 All content ...

173

76 FR 35938 - The Designation of Othman al-Ghamdi Also Known as Al Umairah al-Ghamdi, Also Known as Uthman al...  

Federal Register 2010, 2011, 2012, 2013

...as Othman Ahmed Othman al-Omirah as a Specially Designated Global Terrorist Pursuant to Section 1(b) of Executive Order 13224...nationals or the national security, foreign policy, or economy of the United States. Consistent with the determination...

2011-06-20

174

Serum and CSF immunological findings in ALS.  

PubMed

Serum and CSF immunological findings were analysed in 37 patients with amyotrophic lateral sclerosis (ALS). ALS patients had significantly higher mean values of serum IgG and complement component C4 and significantly lower mean value of total haemolytic titre of complement (THC) compared with normal controls. Incidence of immune complexes (ICs) was significantly higher in sera of ALS patients than in normal controls. There was no significant difference regarding mean serum levels of IgM, IgA, and complement components C3 and Factor B between patients and controls. The blood-brain barrier (BBB) damage was found in 46% of patients. Intrathecal IgG synthesis was detected in six patients (16%). These results support the hypothesis of immune system involvement in ALS. PMID:2017904

Apostolski, S; Nikoli?, J; Bugarski-Prokopljevi?, C; Mileti?, V; Pavlovi?, S; Filipovi?, S

1991-02-01

175

Al speciation in silicate glasses and melts  

NASA Astrophysics Data System (ADS)

The first human glasses were made 3500 BC. It was essentially sodo-lime silicate glass. To improve the chemical resistance, the thermal properties and increase the viscosity it is interesting to add aluminum in these silicates. But what is the speciation of the aluminum and how it varies according to the chemical composition and to the temperature? The aluminum appears essentially in four or five fold coordination in glasses and melts melted. The proportion of [5]Al varies according to the alkaline or to the earth-alkaline content and to the temperature. We shall present in a first part the influence of the network-modifier on the proportion of [5]Al and then we shall present some new results of absorption of high-temperature using NMR and XANES spectroscopy at the Al K-edge. Finally, from glass transition temperature measurements we propose to explain that [5]Al can be a new network former.

Neuville, Daniel; Florian, Pierre; Montouillout, Valérie; Le Losq, Charles; Massiot, Dominique

2010-05-01

176

Substitutional alloy of Ce and Al  

PubMed Central

The formation of substitutional alloys has been restricted to elements with similar atomic radii and electronegativity. Using high-pressure at 298 K, we synthesized a face-centered cubic disordered alloy of highly dissimilar elements (large Ce and small Al atoms) by compressing the Ce3Al intermetallic compound >15 GPa or the Ce3Al metallic glass >25 GPa. Synchrotron X-ray diffraction, Ce L3-edge absorption spectroscopy, and ab initio calculations revealed that the pressure-induced Kondo volume collapse and 4f electron delocalization of Ce reduced the differences between Ce and Al and brought them within the Hume-Rothery (HR) limit for substitutional alloying. The alloy remained after complete release of pressure, which was also accompanied by the transformation of Ce back to its ambient 4f electron localized state and reversal of the Kondo volume collapse, resulting in a non-HR alloy at ambient conditions.

Zeng, Qiao-Shi; Ding, Yang; Mao, Wendy L.; Luo, Wei; Blomqvist, Andreas; Ahuja, Rajeev; Yang, Wenge; Shu, Jinfu; Sinogeikin, Stas V.; Meng, Yue; Brewe, Dale L.; Jiang, Jian-Zhong; Mao, Ho-kwang

2009-01-01

177

Precauciones frente al consumo de huevos  

Center for Food Safety and Applied Nutrition (CFSAN)

Text Version... se puede extender desde el intestino al torrente sanguíneo y luego a otros lugares del cuerpo, lo que puede provocar la muerte, a menos que el ... More results from www.fda.gov/downloads/food/resourcesforyou

178

Precauciones frente al consumo de huevos  

Center for Food Safety and Applied Nutrition (CFSAN)

Text VersionPage 1. Precauciones frente al consumo de huevos October 2011 Lo que usted debe saber Los ... congelada. October 2011 2 More results from www.fda.gov/downloads/food/foodborneillnesscontaminants

179

Access to Iplex for Patients with ALS  

Center for Drug Evaluation (CDER)

... FDA Position on Allowing Patients with ALS Access to Iplex under an IND; FDA Summary of Controlled Clinical Data for Human IGF-1 in Treatment ... More results from www.fda.gov/drugs/resourcesforyou/healthprofessionals

180

Al Qaeda: Statements and Evolving Ideology.  

National Technical Information Service (NTIS)

Osama Bin Laden and the Al Qaeda terrorist network have conducted a sophisticated public relations and media campaign over the last 10 years. Terrorism analysts believe that these messages have been designed to elicit psychological reactions and communica...

C. M. Blanchard

2006-01-01

181

Al Qaeda: Statements and Evolving Ideology.  

National Technical Information Service (NTIS)

Osama Bin Laden and the Al Qaeda terrorist network have conducted a sophisticated public relations and media campaign over the last decade. Terrorism analysts believe that these messages have been designed to elicit psychological reactions and communicate...

C. M. Blanchard

2007-01-01

182

Al Qaeda: Statements and Evolving Ideology.  

National Technical Information Service (NTIS)

Al Qaeda leaders and affiliates have conducted sophisticated public relations and media campaigns since the mid-1990s. Terrorism analysts believe that these campaigns have been designed to elicit psychological reactions and communicate complex political m...

C. M. Blanchard

2007-01-01

183

Western Baldwin County, AL Grid Interconnection Project  

SciTech Connect

The Objective of this Project was to provide an additional supply of electricity to the affected portions of Baldwin County, AL through the purchase, installation, and operation of certain substation equipment.

Thomas DeBell

2011-09-30

184

Interdiffusion in the Mg-Al System and Intrinsic Diffusion in ?-Mg2Al3  

NASA Astrophysics Data System (ADS)

Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96 pct) and Al (99.999 pct). Diffusion anneals were carried out at 573 K, 623 K and 673 K (300 °C, 350 °C and 400 °C) for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopes were used to identify the formation of the intermetallic phases, ?-Mg17Al12, and ?-Mg2Al3, as well as the absence of the ?-Mg23Al30 in the diffusion couples. The thicknesses of the ?-Mg17Al12 and ?-Mg2Al3 phases were measured and the parabolic growth constants were calculated to determine the activation energies for growth. Concentration profiles were determined with electron microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, ?-Mg17Al12, ?-Mg2Al3, and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Integrated and average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the ?-Mg2Al3 phase, followed by ?-Mg17Al12, Al-solid solution, and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann's analysis ( e.g., marker plane) were determined for the ~ Mg-62 at. pct Al in the ?-Mg2Al3 phase. Activation energies and the pre-exponential factors for the interdiffusion and intrinsic diffusion coefficients were calculated for the temperature range examined. The ?-Mg2Al3 phase was found to have the lowest activation energies for growth and interdiffusion among all four phases studied. At the marker location in the ?-Mg2Al3 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 with the available self-diffusion and impurity diffusion data from the literature. Thermodynamic factor, tracer diffusion coefficients, and atomic mobilities at the marker plane composition were approximated using the available literature values of Mg activity in the ?-Mg2Al3 phase.

Brennan, Sarah; Bermudez, Katrina; Kulkarni, Nagraj S.; Sohn, Yongho

2012-11-01

185

Hydrogen diffusion in Al-Li alloys  

Microsoft Academic Search

The diffusion coefficients of hydrogen in binary Al-Li alloys containing 1,2, and 3 wt pct Li have been determined from desorption\\u000a curves of samples saturated with hydrogen at 473 to 873 K. Within this temperature range, the diffusivity of hydrogen in the\\u000a binary Al-Li alloys investigated has an Arrhenius-type temperature dependence and follows the equation of the general formD =

P. N. Anyalebechi

1990-01-01

186

Serrated yielding in Al-Li alloys  

Microsoft Academic Search

Serrated yielding (SY) during tensile testing has been observed in Al-Li alloys, both in the binary and the commercial quaternary alloys, in single crystal as well as polycrystalline materials. Serrated yielding is commonly explained by a dynamic strain aging (DSA) model developed by McCormick and van den Beukel. All the solute elements present in Al-Li alloys, viz., Mg, Cu and

S. Kumar; H. B. McShane

1993-01-01

187

AlN antiresonant layer ARROW waveguides  

Microsoft Academic Search

Aluminum Nitride (AlN) is a wide band gap III-V semiconductor material often used for optical applications due to its transparency and high refractive index. We have produced and characterized AlN thin films by reactive r.f. magnetron sputtering in different Ar-N2 atmospheres in order to verify the best gaseous concentration to be utilized as anti-resonant layer in ARROW waveguides. The corresponding

M. V. Pelegrini; D. O. Carvalho; M. I. Alayo; I. Pereyra

2010-01-01

188

Electric quadrupole moment of 31Al  

NASA Astrophysics Data System (ADS)

The electric quadrupole moment Q for the ground state of 31Al (I? = 5/2+) was measured by means of the ? ray-detected nuclear quadrupole resonance. A spin-polarized radioactive beam of 31Al was produced in the projectile-fragmentation reaction of a 40Ar beam on a 93Nb target. For the Q moment measurement, we developed a new radio-frequency application system to induce the spin reversal.

Nagae, D.; Ueno, H.; Kameda, D.; Takemura, M.; Asahi, K.; Takase, K.; Yoshimi, A.; Sugimoto, T.; Shimada, K.; Nagatomo, T.; Uchida, M.; Arai, T.; Inoue, T.; Kagami, S.; Hatakeyama, N.; Murata, J.; Kawamura, H.; Narita, K.

2008-10-01

189

Transition element modifications of Al-Li  

Microsoft Academic Search

The development of aluminum-lithium metallurgy has led to alloys with unsurpassed combinations of density, specific strength, and specific modulus. This paper describes recent advances in the modification of aluminum-lithium binary alloys through additions of the Group IV-A transition metals (titanium, zirconium, and hafnium). These elements lead to a duplex precipitation hardening behavior through the formation of Al3Li and Al3(TM,Li) (TM

F. W. Gayle; N. F. Levoy; J. B. Vandersande

1987-01-01

190

Sprachlich-kulturelle Heterogenität als Unterrichtsbedingung  

Microsoft Academic Search

Sprachlich-kulturelle Heterogenität in Bildungseinrichtungen ist seit mehr als drei Jahrzehnten eine Realität, die erst in\\u000a den letzten Jahren als eine fast durchgängige Rahmenbedingung von Schule und Unterricht zur Kenntnis genommen wird. Bereits\\u000a 30 % der Kinder zwischen sechs und zehn Jahren verfügen deutschlandweit über einen „Migrationshintergrund“ (Konsortium Bildungsberichterstattung\\u000a 2006, S. 143). Die größte Aufmerksamkeit erfährt seitdem die frühe Sprachförderung, da

Agi Schründer-Lenzen

191

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

192

17th Annual ALS Users' Association Meeting  

SciTech Connect

It's not exactly Russian roulette, but scheduling October events outdoors is not risk-free, even in usually sunny California. An overflow crowd of more than 400 registered users, ALS staff, and vendors enjoyed a full indoor program featuring science highlights and workshops spread over two and a half days from October 18 to October 20. However, a major storm, heralding the onset of the San Francisco Bay Area rainy season, posed a few weather challenges for the events on the ALS patio.

Robinson, Art; Tamura, Lori

2004-11-29

193

Nature and Causality According to Al Bakillani  

Microsoft Academic Search

In this paper we expose the opinion of Al-Bakillani in respect to the question whether the world can be created naturally without an external cause. This opinion is fundamental because it forms the basis of the Ash'arites opinion on the subject of natural causality. For this reason we studied the three main versions of the problem as presented by al-Bakillani,

M. B. Altaie

194

Chronoamperometric studies of pitting corrosion of Al and (Al–Si) alloys by halide ions in neutral sulphate solutions  

Microsoft Academic Search

The pitting corrosion of Al, (Al+6%Si), and (Al+18%Si) alloys in neutral 0.50 M Na2SO4 solution in the absence and presence of NaCl, NaBr and NaI under the influence of various experimental variables has been studied by using potentiodynamic and chronoamperometric techniques. The results showed that the pitting corrosion resistance of the three Al samples decreases in the order: (Al+18%Si)>(Al+6%Si)>Al. The

Sayed S Abdel Rehim; Hamdi H Hassan; Mohammed A Amin

2004-01-01

195

Formation of Al3Ti/Mg composite by powder metallurgy of Mg Al Ti system  

NASA Astrophysics Data System (ADS)

An in situ titanium trialuminide (Al3Ti)-particle-reinforced magnesium matrix composite has been successfully fabricated by the powder metallurgy of a Mg-Al-Ti system. The reaction processes and formation mechanism for synthesizing the composite were studied by differential scanning calorimetry (DSC), x-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). Al3Ti particles are found to be synthesized in situ in the Mg alloy matrix. During the reaction sintering of the Mg-Al-Ti system, Al3Ti particles are formed through the reaction of liquid Al with as-dissolved Ti around the Ti particles. The formed intermetallic particles accumulate at the original sites of the Ti particles. As sintering time increases, the accumulated intermetallic particles disperse and reach a relatively homogeneous distribution in the matrix. It is found that the reaction process of the Mg-Al-Ti system is almost the same as that of the Al-Ti system. Mg also acts as a catalytic agent and a diluent in the reactions and shifts the reactions of Al and Ti to lower temperatures. An additional amount of Al is required for eliminating residual Ti and solid-solution strengthening of the Mg matrix.

Yang, Zi R.; Wang, Shu Qi; Cui, Xiang H.; Zhao, Yu T.; Gao, Ming J.; Wei, Min X.

2008-07-01

196

Magnetism in Fe4Al13 and related FeAl intermetallics  

NASA Astrophysics Data System (ADS)

We report the results of an experimental study of FeAl alloys, including Fe4Al13, FeAl2 and Fe2Al5. By using NMR, dc magnetic susceptibility, and specific heat, we found that Fe4Al13 and Fe2Al5 are non-magnetic with some dilute magnetic moments, while FeAl2 can be characterized as a concentrated local moment system. Fe4Al13 is a decagonal quasicrystal approximant with 102 atoms in its unit cell. The ^27Al NMR spin-lattice relaxation indicates a very narrow pseudogap in the electronic density of states [g(E)] in the vicinity of the Fermi energy. The observations could be fit assuming a parabolic variation of g(E), consistent with observations in other quasicrystals and approximants. NMR lineshape measurements also agree with this analysis, and show that the system is dilute-magnetic, in strong contrast to the FeAl2 ordered intermetallic. We use specific heat to analyze the dilute moment density. This work was supported by the Robert A. Welch Foundation, Grant No. A-1526, by the National Science Foundation (DMR-0103455), and by Texas A&M University through the Telecommunications and Informatics Task Force.

Chi, Ji; Li, Yang; Gou, Weiping; Goruganti, V.; Rathnayaka, K. D. D.; Ross, Joseph H., Jr.

2006-03-01

197

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

198

Differential corticospinal tract degeneration in homozygous 'D90A' SOD-1 ALS and sporadic ALS  

PubMed Central

Background The homogeneous genotype and stereotyped phenotype of a unique familial form of amyotrophic lateral sclerosis (ALS) (patients homozygous for aspartate-to-alanine mutations in codon 90 (homD90A) superoxide dismutase 1) provides an ideal model for studying genotype/phenotype interactions and pathological features compared with heterogeneous apparently sporadic ALS. The authors aimed to use diffusion tensor tractography to quantify and compare changes in the intracerebral corticospinal tracts of patients with both forms of ALS, building on previous work using whole-brain voxelwise group analysis. Method 21 sporadic ALS patients, seven homD90A patients and 20 healthy controls underwent 1.5?T diffusion tensor MRI. Patients were assessed using ‘upper motor neuron burden,’ El Escorial and ALSFR-R scales. The intracranial corticospinal tract was assessed using diffusion tensor tractography measures of fractional anisotropy (FA), mean diffusivity, and radial and axial diffusivity obtained from its entire length. Results Corticospinal tract FA was reduced in sporadic ALS patients compared with both homD90A ALS patients and controls. The diffusion measures in sporadic ALS patients were consistent with anterograde (Wallerian) degeneration of the corticospinal tracts. In sporadic ALS, corticospinal tract FA was related to clinical measures. Despite a similar degree of clinical upper motor neuron dysfunction and disability in homD90A ALS patients compared with sporadic ALS, there were no abnormalities in corticospinal tract diffusion measures compared with controls. Conclusions Diffusion tensor tractography has shown axonal degeneration within the intracerebral portion of the corticospinal tract in sporadic ALS patients, but not those with a homogeneous form of familial ALS. This suggests significant genotypic influences on the phenotype of ALS and may provide clues to slower progression of disease in homD90A patients.

Blain, C R V; Brunton, S; Williams, V C; Leemans, A; Turner, M R; Andersen, P M; Catani, M; Stanton, B R; Ganesalingham, J; Jones, D K; Williams, S C R; Leigh, P N

2011-01-01

199

Oxidation of Ni-Rich Ni-Al Intermetallics.  

National Technical Information Service (NTIS)

The oxidation of Ni-Al intermetallic alloys in the beta-NiAl phase field and in the two phase beta-NiAl/gamma'-Ni3Al phase field has been studied between 1000 and 1400 C. The stoichiometric beta-NiAl alloy doped with Zr was superior to other alloy composi...

J. Doychak J. L. Smialek C. A. Barrett

1988-01-01

200

Optical gain characteristics of non-polar Al-rich AlGaN/AlN quantum well structures  

NASA Astrophysics Data System (ADS)

Optical properties of non-polar Al-rich AlGaN/AlN quantum well (QW) structures were investigated using the multiband effective-mass theory and non-Markovian optical model with the many-body effect. These results are compared with those of the c-plane, i.e., the (0001)-oriented QW structures. The theoretical PL transition wavelength is found to agree well with the experimental result. The optical gain for the x'-polarization is much larger than that for the y'-polarization because the optical matrix element for the x'-polarization is larger than for the y'-polarization. The x'-direction in the non-poalr plane corresponds to c-axis direction. Also, the optical gain for the x'-polarization is shown to decrease with increasing Al composition. This is mainly attribute to the fact that the optical matrix element is decreased due to the reduction in the electron-hole overlap for QW structures with higher Al contents.

Park, Seoung-Hwan

2011-09-01

201

Mechanical properties of Ni{sub 3}Al and FeAl: Recent developments  

SciTech Connect

Recent developments in the understanding of the ductility and fracture behavior of Ni{sub 3}Al and FeAl are reviewed. Both intrinsic factors (e.g., alloy stoichiometry), and extrinsic factors (e.g., environment) have been shown to affect their mechanical properties. Of all the recent developments, perhaps the most significant is the realization that Ni{sub 3}Al and FeAl are intrinsically ductile (at least on the Al-deficient side of stoichiometry); their brittleness when tested in ambient air is due mainly to environmental embrittlement. Another intriguing discovery is that boron embrittles Ni{sub 3}Al in gaseous hydrogen (until recently, B was though to have only beneficial, or at most neutral, effects). The authors review these and other recent discoveries and discuss, wherever possible, the underlying physical mechanisms giving rise to the observed mechanical behavior.

George, E.P.; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1997-08-01

202

Thermal Properties in the MgAl2O4-Al2O3 System  

SciTech Connect

Compositional effects on the thermal diffusivity in the MgAl2O4-Al2O3 system were studied. The lowest thermal diffusivity, 0.0258 +/-5% cm/s, was measured between 79.8 and 83.9 wt% Al2O3 quenched from various temperatures between 1500 and 1700C. All of the chemistries in this range extend past the solvus, but still form a singe super-saturated spinel solid solution, regardless of quenching tempeature. A super-saturated metastable solid solution region was observed at 1500, 1600, and 1700C extending to 83.9, 85.2, and 87.1 wt% Al2O3, respectively. Beyond 83.9% Al2O3 a significant increase in thermal diffusivity, 11.7%, was observed and its attributed to precipiation of Al2O3 through spinodal decomposition.

Wilkerson, Dr. Kelley R. [Missouri University of Science and Technology; Smith, Jeffrey D [ORNL; Hemrick, James Gordon [ORNL

2013-01-01

203

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

204

Relationship between electrical conductivity and stress corrosion cracking susceptibility of Al 7075 and Al 7475 alloys  

SciTech Connect

A relationship between electrical conductivity and stress corrosion cracking (SCC) resistance of the 7,000-series Al-Zn-Mg alloys has been established, although only from the near-peak strength T6 temper to the overaged T73 tempered condition. The present work investigated whether this relationship exists for all periods of aging and for Al alloys with different compositions and grain structures. The materials studied were commercial 2-mm thick Al 7075 (Al-5.76% Zn-2.46% Mg-1.70% Cu-0.20% Cr-0.12% Fe-0.09% Si-0.06% Mn-0.04% Ti) and Al 7475 (Al-5.80% Zn-2.24% Mg-1.53% Cu-0.19% Cr-0.08% Fe-0.02% Si-0.01% Mn-0.02% Ti) alloy plates.

Tsai, T.C.; Chuang, T.H. [National Taiwan Univ., Taipei (Taiwan, Province of China). Inst. of Materials Science and Engineering

1996-06-01

205

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

206

60Co gamma radiation effect on AlGaN/AlN/GaN HEMT devices  

NASA Astrophysics Data System (ADS)

The testing techniques and experimental methods of the 60Co gamma irradiation effect on AlGaN/AlN/GaN high electron mobility transistors (HEMTs) are established. The degradation of the electrical properties of the device under the actual radiation environment are analyzed theoretically, and studies of the total dose effects of gamma radiation on AlGaN/AlN/GaN HEMTs at three different radiation bias conditions are carried out. The degradation patterns of the main parameters of the AlGaN/AlN/GaN HEMTs at different doses are then investigated, and the device parameters that were sensitive to the gamma radiation induced damage and the total dose level induced device damage are obtained.

Wang, Yan-Ping; Luo, Yin-Hong; Wang, Wei; Zhang, Ke-Ying; Guo, Hong-Xia; Guo, Xiao-Qiang; Wang, Yuan-Ming

2013-05-01

207

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

...DEPARTMENT OF STATE [Public Notice 8104] In the Matter of Amendment of the Designation of al-Qa'ida in Iraq, aka Jam'at al Tawhid wa'al-Jihad, aka The Monotheism and Jihad Group, aka The al-Zarqawi Network, aka...

2012-12-11

208

Laser cladding NiCoCrAlY coating on Ti6Al4V  

Microsoft Academic Search

In order to improve wear resistance of titanium alloy, a process of laser cladding NiCoCrAlY coating on Ti-6Al-4V substrate with pre-placed NiCoCrAlY powder was studied. A good coating without cracks and pores was obtained in a proper laser process. The microstructure of the coating was examined using SEM and EDS. There is a metallurgical interface bonding between the coating and

Qingwu Meng; Lin Geng; Dingrui Ni

2005-01-01

209

Nucleation Effect of Ti6Al4V Powder on Al–Si Eutectic Alloy  

Microsoft Academic Search

In this research nucleation effect of Ti-6Al-4 V powder on grain size and tensile strength of Al-12.1% Si eutectic alloy was studied. Metal powder produced from Ti-6Al-4 V machining chips by meshes of 50 and 140 and weight percentages of 0.1, 0.15, 0.2, and 0.25 were used. The microstructure by mesh 50 with 0.15 wt% consists of grain with average size of 6 µm,

Zohair Sarajan

2009-01-01

210

A note on Wang et al's attack on Zhang et al's multiparty quantum secret sharing  

NASA Astrophysics Data System (ADS)

Recently, Wang et al (2008 Phys. Lett. A 373 65) proposed an attack on Zhang et al's (2007 Opt. Commun. 269 418) multiparty quantum secret sharing scheme, in which the first and the last agent are reported to be able to cooperatively eavesdrop on all the secret messages without being detected. In this paper, we show that in Wang et al's attack, on average no more than half the secret messages can be eavesdropped.

Gao, Gan

2012-08-01

211

Anodic Oxidation of Aluminum by Electron Tunneling through Al/Cadmium-Stearate/Al Structure  

NASA Astrophysics Data System (ADS)

The conduction of the monolayer Langmuir-Blodgett(LB) film consisting of Cadmium-Stearate(CdSt) may be explained by an electron tunneling process. The tunneling current through the Al/CdSt/Al sample showed a great decrease with time when a constant voltage was applied in air. Such a phenomenon seems to result from the growth of an Al2O3 layer by the anodic oxidation of the aluminum electrode enhanced by the electron tunneling.

Okazaki, Choichiro; Kuniyoshi, Shigekazu; Kudo, Kazuhiro; Tanaka, Kuniaki

1989-11-01

212

Tensile deformation behavior of a sub-micrometer Al 2O 3\\/6061Al composite  

Microsoft Academic Search

A 0.3?m Al2O3\\/6061Al composite with 33% volume fraction of Al2O3 was fabricated by the patented squeeze-casting technology. The tensile properties were studied, and the dynamic tensile deformation behavior was investigated by an in situ TEM tensile technique. The as-cast composite exhibits excellent tensile properties with a fracture strength of 504MPa, and the strength increases to 579MPa after a T6 treatment.

Qiang Zhang; Gaohui Wu; Longtao Jiang

2008-01-01

213

NMR measurements and hybridization behavior in Al_3Zr, Al_3Hf, and related intermetallics  

Microsoft Academic Search

We report ^27Al NMR measurements on aluminum-rich intermetallics, including the DO_23-structured alloys Al_3Zr and Al_3Hf, and related close-packed structures. We determined the quadrupole splittings and Knight shifts, giving site-dependent structural information. The Knight shift tensors indicate strong directional bonding in the DO_23 alloys, despite the modified close-pack structures. This is especially true for sites I and III. The non-zero asymmetry

Chin Shan Lue Ross Jr.

2001-01-01

214

Cryptanalysis of Khan et al.'s dynamic ID-based remote user authentication scheme  

Microsoft Academic Search

Recently, Khan et al. showed that Wang et al.'s dynamic ID-based remote user authentication scheme is not feasible for real-life implementations such as without preserving anonymity of a user during authentication, user cannot choose the password he\\/she wants, no provision for revocation of lost or stolen smart card, and can not provide session key agreement. Consequently, an improved version of

Chun-Ta Li; Chen-Ju Liu; Cheng-Chi Lee; Chin-Wen Lee

2010-01-01

215

Mechanism of Nonalloyed Al Ohmic Contacts to n-Type ZnO:Al Epitaxial Layer  

Microsoft Academic Search

The mechanism of Al ohmic contacts to n-type zinc oxide (ZnO:Al) epitaxial layer was investigated. The formation of an Al-ZnO interfacial phase at room temperature was responsible for the low specific resistivity (8± 0.3× 10-4 Omegacm2). The results of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) depth profiles, and glancing angle X-ray diffraction (GXRD) indicate that an interfacial reaction

Han-Ki Kim; Tae-Yeon Seong; Koung-Kook Kim; Seoug-Ju Park; Young Soo Yoon; Ilesanmi Adesida

2004-01-01

216

Long range order and vacancy properties in Al-rich Fe{sub 3}Al and Fe{sub 3}Al(Cr) alloys  

SciTech Connect

Neutron powder diffraction measurements have been carried out in situ from room temperature to about 100 C in Fe28Al (28 at.% Al), Fe32.5Al (32.5 at.% Al) and Fe28Al15Cr (28 at.% Al, 5 at.% Cr) alloys. X-ray diffraction and TEM studies provided supporting information. The data were analyzed to obtain information about the temperature dependence of the DO{sub 3} and B2 long range order parameters, the location of the Cr atoms and their effect on the ordering energies, and on the vacancy formation and migration properties in Fe28Al and Fe32.5Al alloys. The location of the ternary alloying addition in DO{sub 3} and B2 ordered Al-rich Fe{sub 3}Al is shown to be consistent with considerations of interatomic bond energies.

Kim, S.M. [AECL, Chalk River, Ontario (Canada). Chalk River Labs.; Morris, D.G. [Univ. of Neuchatel (Switzerland). Inst. of Structural Metallurgy

1998-05-01

217

Theoretical and Experimental Study of Relaxations in Al3Ti and Al3Zr Ordered Phases  

NASA Astrophysics Data System (ADS)

The aim of the present investigation was to elucidate the role of structural relaxations in determining the relative stability of L12, D022, and D023 structures in Al3Ti and Al3Zr. This task was accomplished by a unique combination of total-energy electronic structure calculations and (for Al3Zr) high resolution neutron diffraction with Reitveld refinement. Calculated and measured atomic displacements are in excellent agreement. Local relaxation is found to be responsible for the stability of the D023 structure in Al3Zr, in agreement with experimental evidence.

Amador, C.; Hoyt, J. J.; Chakoumakos, B. C.; de Fontaine, D.

1995-06-01

218

Al-matrix composite materials reinforced by Al-Cu-Fe particles  

NASA Astrophysics Data System (ADS)

Al-matrix material composites were produced using hot isostatic pressing technique, starting with pure Al and icosahedral (i) Al-Cu-Fe powders. Depending on the processing temperature, the final reinforcement particles are either still of the initial i-phase or transformed into the tetragonal ?-Al00.70Cu0.20Fe0.10 crystalline phase. Compression tests performed in the temperature range 293K - 823K on the two types of composite, i.e. Al/i and Al/?, indicate that the flow stress of both composites is strongly temperature dependent and exhibit distinct regimes with increasing temperature. Differences exist between the two composites, in particul ar in yield stress values. In the low temperatureregime (T <= 570K), the yield stress of the Al/? composite is nearly 75% higher than that of the Al/i composite, while for T > 570K both composites exhibit similar yield stress values. The results are interpreted in terms of load transfer contribution between the matrix and the reinforcement particles and elementary dislocation mechanisms in the Al matrix.

Bonneville, J.; Laplanche, G.; Joulain, A.; Gauthier-Brunet, V.; Dubois, S.

2010-07-01

219

Annealing effects on Al and Al-Si contacts with 3C-SiC  

Microsoft Academic Search

Annealing effects on the current-voltage characteristics of Al and Al-Si contacts with n-type and p-type 3C-SiC films, epitaxially grown on Si by chemical vapor deposition, have been investigated. Al electrodes on n-type 3C-SiC show ohmic characteristics stable up to 400 C, but show distinct rectifying characteristics with annealing at 900 C. To the contrary, Al on p-type 3C-SiC clearly changes

Hiroshi Daimon; Mitsugu Yamanaka; Eiichiro Sakuma; Shunji Misawa; Sadafumi Yoshida

1986-01-01

220

Reactions of CO2 on solid and liquid Al100+.  

PubMed

The reactions of CO(2) on the Al(100)(+) cluster have been investigated as a function of cluster temperature (300-1100 K) and relative kinetic energy (0.2-10 eV). Two main products are observed at low cluster temperature: Al(100)O(+) (which is believed to result from a stripping reaction) and Al(100)CO(2)(+) from complex formation. As the cluster temperature is raised, both products dissociate by loss of Al(2)O. Al(100)O(+) forms Al(98)(+), while Al(100)CO(2)(+) forms Al(98)CO(+) and Al(96)C(+). In both cases, loss of Al(2)O turns-on above the melting temperature of Al(100)(+). This presumably occurs because the overall reaction leading to the loss of Al(2)O is significantly less endothermic for the liquid cluster than for the solid. PMID:22680973

Leslie, Katheryne L; Shinholt, Deven; Jarrold, Martin F

2012-06-11

221

77 FR 67689 - Fidelity Aberdeen Street Trust, et al.;  

Federal Register 2010, 2011, 2012, 2013

...812-13731] Fidelity Aberdeen Street Trust, et al.; Notice of Application November 6...1\\ Colchester Street Trust, et al., Investment Company Act Release Nos...amending, Colchester Street Trust, et al., Investment Company Act Release...

2012-11-13

222

75 FR 57846 - Amendment of Class E Airspace; Brewton, AL  

Federal Register 2010, 2011, 2012, 2013

...Amendment of Class E Airspace; Brewton, AL AGENCY: Federal Aviation Administration...at Brewton Municipal Airport, Brewton, AL, by updating the geographic coordinates...of Brewton Municipal Airport, Brewton, AL. This action makes the adjustment....

2010-09-23

223

Effect of elemental powder blending ratio on combustion foaming behavior of porous Al–Ti intermetallics and Al 3Ti\\/Al composites  

Microsoft Academic Search

Porous Al–Ti intermetallics and Al3Ti\\/Al composites were fabricated by combustion foaming process. Fundamentally, aluminum and titanium powders were blended (Al\\/Ti mole blending ratios ranging from 0.33 to 10.0). Additionally, boron carbide (B4C) powder was blended as exothermic agent since the heat of TiC and TiB2 formation is much higher than those of Al–Ti intermetallics. The blended powder compact was heated

Makoto Kobashi; Norio Inoguchi; Naoyuki Kanetake

2010-01-01

224

Regulation of Tomato golden mosaic virus AL2 and AL3 gene expression by a conserved upstream open reading frame.  

PubMed

A translational regulatory mechanism for Tomato golden mosaic virus (TGMV) complementary-sense gene expression has been characterized. TGMV transcribes two mRNAs, AL-1935 and AL-1629 transcripts, both of which contain the AL2 and AL3 open reading frames. However, AL2 is only expressed from AL-1629 whereas AL3 is expressed from both. Three AUG translation initiation codons are located upstream of both the AL2 and AL3 coding regions, within the 5'-untranslated region (UTR) of the AL-1935 transcript. Translation can initiate at the first AUG, specifying the C-terminal 122 amino acids of the AL1 protein (cAL1). Initiation of translation at this AUG is inhibitory for the downstream expression of both AL2 and AL3. This is most likely due to the terminator codon of cAL1 being positioned after the AUG initiation codon for the AL2 ORF. The mechanism by which AL3 is expressed from AL-1935 is currently unknown but a gap between the cAL1 termination codon and the start of AL3 suggests that it may involve reinitiation and/or internal initiation. In contrast, expression of AL3 from AL-1629 most likely occurs via leaky ribosome scanning since the AL3 initiation codon occurs before the terminator codon of AL2. Mutation of the AUG encoding cAL1 in the curtovirus, Spinach curly top virus, leads to increased infectivity as measured by a shorter latent period. Together this suggests that geminiviruses use a post-translational regulatory mechanism to regulate the synthesis of viral proteins important for replication and suppression of host defenses. PMID:19012941

Shung, Chia-Yi; Sunter, Garry

2008-11-14

225

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

226

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.

King, Oliver D.

2013-01-01

227

The mechanical properties of FeAl  

SciTech Connect

Only in the last few years has progress been made in obtaining reproducible mechanical properties data for FeAl. Two sets of observations are the foundation of this progress. The first is that the large vacancy concentrations that exist in FeAl at high temperature are easily retained at low temperature and that these strongly affect the low-temperature mechanical properties. The second is that RT ductility is adversely affected by water vapor. Purpose of this paper is not to present a comprehensive overview of the mechanical properties of FeAl but rather to highlight our understanding of key phenomena and to show how an understanding of the factors which control the yield strength and fracture behavior has followed the discovery of the above two effects. 87 refs, 9 figs.

Baker, I. [Dartmouth Coll., Hanover, NH (United States); George, E.P. [Oak Ridge National Lab., TN (United States)

1996-12-31

228

Boron strengthening in FeAl  

SciTech Connect

The effect of boron on the strength of B2-structured FeAl is considered as a function of composition, grain size and temperature. Boron does not affect the concentrations of antisite atoms or vacancies present, with the former increasing and the latter decreasing with increasing deviation from the stoichiometric composition. When vacancies are absent, the strength increase per at. % B per unit lattice strain, {Delta}{sigma}/({Delta}c x {epsilon}) increases with increasing aluminum concentration, but when vacancies are present (>45 at. % Al), {Delta}{sigma}/({Delta}c x {epsilon}) decreases again. Boron increases grain size strengthening in FeAl. B strengthening is roughly independent of temperature up to the yield strength peak but above the point, when diffusion-assisted deformation occurs, boron strengthening increases dramatically.

Baker, I.; Li, X.; Xiao, H.; Klein, O.; Nelson, C. [Dartmouth Coll., Hanover, NH (United States). Thayer School of Engineering; Carleton, R.L.; George, E.P. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

1998-11-01

229

Stress granules as crucibles of ALS pathogenesis.  

PubMed

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

Li, Yun R; King, Oliver D; Shorter, James; Gitler, Aaron D

2013-04-29

230

Determinacion espectrografica de impurezas en materiales ceramicos para fusion nuclear III. Analisis de oxido de magnesio. (Spectrographic determination of impurities in ceramic materials for nuclear fusion reactors III. Analysis of magnesium oxide).  

National Technical Information Service (NTIS)

The determination of minor and trace elements in the magnesium oxide, considered as possible ceramic material in thermonuclear fusion reactors, has been studied. The concentration ranges are 0.1 - 0.3 % for Ca, Si and Y, and at the ppm level for Al, Co, C...

A. M. Melon M. Roca M. I. Rucandio

1992-01-01

231

Influence of Al 2O 3 particulate on the aging response of A356 Al-based composites  

Microsoft Academic Search

A356 Al alloy reinforced with Al2O3 particulates of different sizes (25?m angular or 40?m microsphere) and volume fractions (5, 10 and 20vol.%) was prepared using vortex method. The influence of Al2O3 particulates on the precipitation and hardening behavior of the A356 Al–Al2O3 composites was studied. It was found that the MgAl2O4 spinel formed at the interface led to Mg depletion

A. Daoud; W. Reif

2002-01-01

232

Layered growth of the quasicrystalline decagonal Al3Pd phase in Al\\/Pd lateral diffusion couples  

Microsoft Academic Search

The solid-state reaction in an Al\\/Pd lateral diffusion couple starts with the growth of the crystalline Al3Pd2(delta) phase. When the growth of Al3Pd2 reaches its critical length, the quasicrystalline decagonal Al3Pd(gamma') phase starts to grow and both the Al3Pd2 and Al3Pd phases continue to grow afterwards. We have fitted this simultaneous growth with a recently proposed model of kinetic suppression

B. Blanpain; J. W. Mayer; Joyce C. Liu; K. N. Tu

1990-01-01

233

The evaluation and measurement of AlGaN epitaxial layer with high Al mole fraction  

NASA Astrophysics Data System (ADS)

The epitaxial layer quality of AlxGa1-xN (x>0.6) on sapphire substrate grown by metal organic chemical vapor deposition (MOCVD) needs to be further improved. In this paper, we evaluated the properties of defects, lattice mismatch between epitaxial layer and substrate, crystal quality and conductivity for these high Al mole fraction materials from the viewpoint of fabricating high performance solar blind detectors by comprehensive utilizing various undamaged measurements. The measurement of transmission spectrum was used to evaluate the absorption edge, band gap, mole fraction of Al content, hetero-epitaxial interface, and transmissivity in the ultraviolet spectral range. X-ray diffraction (XRD) was used to measure the component of the AlGaN material, uniformity of the material and crystal quality. The conductivity of the surface layer of the AlGaN film material was obtained by using high precision current-voltage curve measurement. In short, the material quality, optical and electrical properties, and uniformity for high Al mole fraction AlGaN epitaxial layers were qualitatively or quantitatively measured and analyzed. These works lay the foundation for manufacturing high performance solar blind ultraviolet detectors based on high Al mole fraction AlGaN epitaxial materials on sapphire substrate.

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

2009-08-01

234

Spark plasma and microwave sintering of Al6061 and Al2124 alloys  

NASA Astrophysics Data System (ADS)

Despite the importance of aluminum alloys as candidate materials for applications in aerospace and automotive industries, very little work has been published on spark plasma and microwave processing of aluminum alloys. In the present work, the possibility was explored to process Al2124 and Al6061 alloys by spark plasma and microwave sintering techniques, and the microstructures and properties were compared. The alloys were sintered for 20 min at 400, 450, and 500°C. It is found that compared to microwave sintering, spark plasma sintering is an effective way to obtain homogenous, dense, and hard alloys. Fully dense (100%) Al6061 and Al2124 alloys were obtained by spark plasma sintering for 20 min at 450 and 500°C, respectively. Maximum relative densities were achieved for Al6061 (92.52%) and Al2124 (93.52%) alloys by microwave sintering at 500°C for 20 min. The Vickers microhardness of spark plasma sintered samples increases with the increase of sintering temperature from 400 to 500°C, and reaches the values of Hv 70.16 and Hv 117.10 for Al6061 and Al2124 alloys, respectively. For microwave sintered samples, the microhardness increases with the increase of sintering temperature from 400 to 450°C, and then decreases with the further increase of sintering temperature to 500°C.

Saheb, Nouari

2013-02-01

235

Combustion Synthesis Reactions in Cold-Rolled Ni/Al and Ti/Al Multilayers  

NASA Astrophysics Data System (ADS)

In this article, a cold rolling method was developed to fabricate Ni/Al and Ti/Al multilayer foils, and the combustion synthesis reactions in the cold-rolled foils were investigated. Combustion synthesis reactions were initiated by heating one end of the cold-rolled foil in a flame for several seconds. The Ni/Al foils went through three reaction stages. The first reaction stage was a displacement of reaction zone with Al3Ni as the reaction product. During the second stage, the part of the foil in the flame underwent thermal explosion. In the last stage, the heat released by thermal explosion triggered a self-propagating high-temperature synthesis (SHS) reaction across the foil that resulted in the formation of AlNi. In contrast, the Ti/Al foils experienced only two reaction stages. First, a displacement of the reaction zone propagated across the foil with formation of Al3Ti at the Ti/Al interface. Then a thermal explosion reaction occurred in the part of foil that was heated in the flame, resulting in many different phases in the reacted foil.

Qiu, Xiaotun; Liu, Ranran; Guo, Shengmin; Graeter, Jesse Harris; Kecskes, Laszlo; Wang, Jiaping

2009-07-01

236

On Approaches to Learning versus Learning Styles: A Reply to Duff et al.'s Comment  

Microsoft Academic Search

The Comment of Duff, Dobie and Guo (forthcoming) offers variable usefulness. At its best, Duff et al.'s Comment makes an earnest attempt to promote dialogue and debate. For example, their Comment offers new ways to reconceptualize our two papers, and further offers challenges to how the research was motivated and executed. As such, their Comment provides glimpses of the healthy

Ralph W. Adler; Rosalind H. Whiting; Kate Wynn-Williams

2008-01-01

237

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

238

Al Qaeda and al Qaeda in the Arabian Peninsula: Inspired, Homegrown Terrorism in the United States  

Microsoft Academic Search

This article analyzes a facet of the phenomenon of al Qaeda (AQ) and al Qaeda in the Arabian Peninsula (AQAP)-inspired terrorism on U.S. soil. The twenty case studies addressed in this piece are illustrative of the nature of the current threat as well as foreshadows future risks of transnational jihad.

Dean C. Alexander

2011-01-01

239

Fabrication and Mechanical Properties of Ni3 Al--Al2 O3 Composites.  

National Technical Information Service (NTIS)

The objective of this study is to develop a metal-matrix composite based on the intermetallic alloy Ni3 Al reinforced with Al2 O3 fibers, with improved high-temperature strength and lower density compared to the matrix material. This paper summarizes resu...

C. G. McKamey G. L. Povirk J. A. Horton T. N. Tiegs E. K. Ohriner

1988-01-01

240

Electronic circuits having NiAl and Ni.sub.3 Al substrates  

DOEpatents

An electronic circuit component having improved mechanical properties and thermal conductivity comprises NiAl and/or Ni.sub.3 Al, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

Deevi, Seetharama C. (Midlothian, VA); Sikka, Vinod K. (Oak Ridge, TN)

1999-01-01

241

Powder size effect on cell morphology of combustion synthesized porous Al 3Ti\\/Al composite  

Microsoft Academic Search

Porous Al3Ti\\/Al composites were fabricated by the combustion foaming process and the effect of elemental powder size on porosity and cell morphology was investigated. High porosity was obtained by using the small titanium powders. Pores also became larger and more spherical by using the small titanium powders. Pore size became smaller and porosity became higher by decreasing the aluminum powder

Makoto Kobashi; Norio Inoguchi; Naoyuki Kanetake

2010-01-01

242

Nb3Al Development for HEP Applications  

SciTech Connect

Recent developments in Nb3Al strand for HEP applications are presented and discussed. The present state of available precursor is detailed. Two routes have been shown to lead to successful construction of MF NbAl composite wires. An extrusion method has so far produced the highest filament counts and smallest filament diameters, but requires more processing steps. A direct restack and draw approach has also been demonstrated which minimizes the number of processing steps while still leading to a high performance conductor. This latter route also allows for a lower cost per billet, potentially allowing the exploration of more process parameters.

Sumption, M.D.; Buta, F.; Collings, E.W. [Laboratories for Applied Superconductivity and Magnetism (LASM), MSE Dept, The Ohio State University, Columbus, OH 43210 (United States); Tomsic, M.; Phillips, J.; McFadden, K. [Hyper Tech Research Inc., Troy, OH 45373 (United States); Wu, X

2004-06-28

243

Surface phonon polariton characteristics of In(0.04)Al(0.06)Ga(0.90)N/AlN/Al(2)O(3) heterostructure.  

PubMed

Surface phonon polariton (SPP) characteristics of In(0.04)Al(0.06)Ga(0.90)N/AlN/Al(2)O(3) heterostructure are investigated by means of p-polarized infrared (IR) attenuated total reflection spectroscopy. Two absorption dips corresponding to In(0.04)Al(0.06)Ga(0.90)N SPP modes are observed. In addition, two prominent dips and one relatively weak and broad dip corresponding to the Al(2)O(3) SPP mode, In(0.04)Al(0.06)Ga(0.90)N/Al(2)O(3) interface mode, and Al(2)O(3) bulk polariton mode, respectively, are clearly seen. No surface mode feature originating from the AlN layer is observed because it is too thin. Overall, the observations are in good agreement with the theoretical predictions. PMID:20588890

Ng, S S; Lee, S C; Bakhori, S K Mohd; Hassan, Z; Abu Hassan, H; Yakovlev, V A; Novikova, N N; Vinogradov, E A

2010-05-10

244

AlN homoepitaxial growth on sublimation-AlN substrate by low-pressure HVPE  

NASA Astrophysics Data System (ADS)

Crack-free thick AlN layers with low impurity concentrations were grown on free-standing AlN substrates fabricated by a sublimation method. Cracks due to tensile stresses were generated in the overgrowth layer when using on-axis AlN (0 0 0 1) substrates, as indicated by Raman scattering spectroscopy. In contrast, cracks were not generated when using 5° off-angle AlN (0 0 0 1) substrates. High crystalline quality was indicated by X-ray rocking curve (XRC) analysis. The full width at half maximum (FWHM) values of the (0 0 0 2) and (1 0–1 0) diffractions were 277 and 306 arcsec, respectively. Secondary ion mass spectrometry (SIMS) measurements indicated that the Si and C impurity concentrations were reduced to half of those in the sublimation-grown AlN substrates.

Nomura, Takuya; Okumura, Kenta; Miyake, Hideto; Hiramatsu, Kazumasa; Eryu, Osamu; Yamada, Yoichi

2012-07-01

245

26Al+ p elastic and inelastic scattering reactions and galactic abundances of 26Al  

SciTech Connect

Galactic 26Al is the first radioactive nucleus to be positively identified by -ray astronomy with detection of the 1.809 MeV ray associated with its decay. This nucleus is destroyed in astrophysical environments in the 26Al(p, )27Si and inelastic 26Al+p scattering reactions where properties of 27Si levels determine reaction rates. To investigate these properties, elastic and inelastic 26Al+p scattering reactions were measured between Ec.m. = 0.5 1.5 MeV at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). A candidate for a new resonance in the 26Al(p, )27Si reaction was identified. Upper limits were also set on the strengths of postulated resonances and on the cross section of the inelastic reaction, but there is little effect on current reaction rate calculations.

Pittman, S. T. [University of Tennessee, Knoxville (UTK); Bardayan, Daniel W [ORNL; Chae, K. Y. [University of Tennessee, Knoxville (UTK); Chipps, K. [Colorado School of Mines, Golden; Jones, K. L. [Rutgers University; Kozub, R. L. [Tennessee Technological University; Matei, Catalin [Oak Ridge Associated Universities (ORAU); Matos, M. [Louisiana State University; Moazen, Brian [University of Tennessee, Knoxville (UTK); Nesaraja, Caroline D [ORNL; O'Malley, Patrick [Rutgers University; Pain, Steven D [ORNL; Parker, P.D. [Yale University; Peters, W. A. [Rutgers University; ShrinerJr., J. F. [Tennessee Technological University; Smith, Michael Scott [ORNL

2012-01-01

246

An impedance study of complex Al/Cu-Al2O3 electrode  

NASA Astrophysics Data System (ADS)

Electrochemical impedance spectroscopy (EIS) was used to investigate different Cu deposition regimes on Al surface obtained by internal electrolysis and to characterize properties of fabricated electrodes. EIS experimental data confirmed that Cu deposition by internal electrolysis is realized and the complex electrode system is obtained. The main difficulty in preparation of Al/Cu electrodes is to prevent aluminium oxidation before and during electrochemical deposition of Cu particles. In this work NaCl, CH3COONa, K2SO4, mono- and diammonium citrate electrolytes were examined to determine their suitability for impedance measurements. Al/Cu-Al2O3 electrode composition was approved by equivalent circuit analysis, optical and scanning electron microscope methods. The most optimal Cu deposition mode using internal electrolysis was determined. The obtained results are promising for future electrochemical fabrication of nanostructures directly on Al surfaces by internal electrolysis.

Denisova, J.; Katkevics, J.; Erts, D.; Viksna, A.

2011-06-01

247

Evidence for {open_quotes}loose spins{close_quotes} in epitaxial Al/Fe/Al  

SciTech Connect

Polarization-dependent Fe K-edge x-ray absorption fine structure measurements of an Al/Fe/Al(001) trilayer reveal a small tetragonal distortion of the Fe sites with c=2.863 {Angstrom} (normal to the film plane) and a=2.874 {Angstrom} (in the film plane). This tetragonal distortion is consistent with the formation of Fe{sub 1{minus}x}Al{sub x} alloys in the vicinity of the roughened Fe{endash}Al trilayer interfaces, and agrees with grazing incidence x-ray reflectivity and magnetometry measurements of the trilayer. The deduced alloyed/roughened interfacial regions are the likely source of Fe {open_quotes}loose spins{close_quotes} as recently suggested by Slonczewki{close_quote}s biquadratic coupling model for the epitaxial Fe/Al/Fe system. {copyright} {ital 1997 American Institute of Physics.}

Gutierrez, C.J.; Selestino, R. [Department of Physics, Southwest Texas State University, San Marcos, Texas 78666 (United States); Mayanovic, R.A. [Department of Physics and Astronomy, Southwest Missouri State University, Springfield, Missouri 65804 (United States); Prinz, G.A. [Naval Research Laboratory, Washington, DC 20375 (United States)

1997-04-01

248

Theoretical study of optical properties in deep ultraviolet Al-rich AlGaN/AIN quantum wells  

NASA Astrophysics Data System (ADS)

Optical properties of deep ultraviolet Al-rich AlGaN/AlN quantum wells (QWs) were theoretically investigated by using the multiband effective-mass theory. The theoretical PL transition wavelength is found to agree well with the experimental result. The internal field in AlGaN/AlN QW structures with lower Al contents is much larger than that in QW structures with higher Al contents. The intensity of the spontaneous emission spectra is shown to be improved with increasing Al content because the optical matrix elements are largely enhanced due to the reduced internal field.

Park, S. H.

2009-03-01

249

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

Microsoft Academic Search

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.

Harish C. Barshilia; B. Deepthi; K. S. Rajam; Kanwal Preet Bhatti; Sujeet Chaudhary

2009-01-01

250

Criteria for the formation of protective Al 2O 3 scales on Fe–Al and Fe–Cr–Al alloys  

Microsoft Academic Search

The conditions for the formation of external alumina scales on binary Fe–Al alloys and the nature of the third-element effect due to chromium additions have been investigated by studying the oxidation at 1000°C in 1atm O2 of a binary Fe–10at.% Al alloy (Fe–10Al) and of two ternary Fe–Cr–10at.% Al alloys containing 5 and 10at.% chromium (Fe–5Cr–10Al and Fe–10Cr–10Al, respectively). An

Z. G. Zhang; F. Gesmundo; P. Y. Hou; Y. Niu

2006-01-01

251

Improved electrical properties in AlGaN\\/GaN heterostructures using AlN\\/GaN superlattice as a quasi-AlGaN barrier  

Microsoft Academic Search

The authors report the electrical properties of two-dimensional electron gas (2DEG) in AlGaN\\/GaN heterostructures using AlN\\/GaN superlattices working as a quasi-AlGaN barrier layer. It is found that the electrical properties (2DEG mobility and sheet carrier density) in the quasi-AlGaN\\/GaN heterostructure are greatly improved compared to those in the conventional alloy-AlGaN\\/GaN one at the high Al composition more than 0.35. The

Y. Kawakami; A. Nakajima; X. Q. Shen; G. Piao; M. Shimizu; H. Okumura

2007-01-01

252

Oxidation of Volatile Organic Compounds on Al 2O 3, Pd\\/Al 2O 3, and PdO\\/Al 2O 3Catalysts  

Microsoft Academic Search

Temperature-programmed desorption (TPD) and oxidation (TPO) were used to study the decomposition and oxidation of methanol, ethanol, acetaldehyde, formic acid, and acetic acid on Al2O3, Pd\\/Al2O3, and PdO\\/Al2O3catalysts. The oxidation and decomposition rates were much higher on Pd\\/Al2O3than on Al2O3, even though the volatile organic compounds (VOCs) were adsorbed on the Al2O3support in both cases. The VOCs surface-diffused to Pd

Eric M Cordi; John L Falconer

1996-01-01

253

Al-Li Alloy Developed by Pechiney.  

National Technical Information Service (NTIS)

An up-to-date view of Al-Li development is presented in terms of both properties and production readiness. Successes achieved to date, mostly where damage tolerance and medium strength targets are concerned, will be outlined. Design allowables, properties...

M. Doudeau P. Meyer D. Constant

1989-01-01

254

Legality of al-Qaeda's Jihad.  

National Technical Information Service (NTIS)

Usama Bin Laden, the leader of al-Qaeda, declared war on the United States in a statement issued in August 1996. With the words, 'It is a duty now on every tribe in the Arab Peninsula to fight in the cause of Allah and to cleanse the land from those occup...

S. M. Pelicano

2011-01-01

255

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

256

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

257

The Plastic Deformation of TiAl.  

National Technical Information Service (NTIS)

The deformation substructure of TiAl (Llo type ordered lattice) tested in compression, and the factors determining it were investigated. Two types of dislocations take part in the plastic deformation, namely a/2(110) and a/2(011). The latter type will dis...

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

1973-01-01

258

Microbial Bioreactor Development in the ALS NSCORT  

Microsoft Academic Search

The NASA Specialized Center of Research and Training in Advanced Life Support (the ALS NSCORT), a partnership of Alabama A & M, Howard, and Purdue Universities, was established by NASA in 2002 to develop technologies that will reduce the Equivalent System Mass (ESM) of regenerative processes within future space life-support systems. A key focus area of NSCORT research has been

Cary Mitchell; Dawn Whitaker; M. Katherine Banks; Albert J. Heber; Ronald F. Turco; Loring F. Nies; James E. Alleman; Sybil E. Sharvelle; Congna Li; Megan Heller

2008-01-01

259

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

260

Microstructural Change of Al on H Implantation.  

National Technical Information Service (NTIS)

Modifications to the subsurface layer of Al on 25 KeV H2(+) ion implantation to fluences of 4 x 10 to the 17th power - 2 x 10 to the 18th power H(+)/sq cm at room temperature were investigated by transmission electron microscopy (TEM) and elastic recoil d...

K. Kamada A. Sagara H. Kinoshita H. Takahashi

1987-01-01

261

Al Qaeda's Organizational Structure and its Evolution  

Microsoft Academic Search

The inner organizational structure of Al Qaeda within the expanded framework of the “Global Jihad movement” has been a subject of much debate between scholars. As will be elaborated later, the “Global Jihad movement” is composed of several elements that possess radical Islamic ideology and conduct operational activity in different regions in the world under the banner of Jihad. The

Rohan Gunaratna; Aviv Oreg

2010-01-01

262

Ternary Dy-Er-Al magnetic refrigerants  

SciTech Connect

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

263

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

264

SPI measurements of Galactic 26Al  

NASA Astrophysics Data System (ADS)

The precision measurement of the 1809 keV gamma-ray line from Galactic 26Al is one of the goals of the SPI spectrometer on INTEGRAL with its Ge detector camera. We aim for determination of the detailed shape of this gamma-ray line, and its variation for different source regions along the plane of the Galaxy. Data from the first part of the core program observations of the first mission year have been inspected. A clear detection of the 26Al line at =~ 5-7 sigma significance demonstrates that SPI will deepen 26Al studies. The line intensity is consistent with expectations from previous experiments, and the line appears narrower than the 5.4 keV FWHM reported by GRIS, more consistent with RHESSI's recent value. Only preliminary statements can be made at this time, however, due to the multi-component background underlying the signal at =~ 40 times higher intensity than the signal from Galactic 26Al.

Diehl, R.; Knödlseder, J.; Lichti, G. G.; Kretschmer, K.; Schanne, S.; Schönfelder, V.; Strong, A. W.; von Kienlin, A.; Weidenspointner, G.; Winkler, C.; Wunderer, C.

2003-11-01

265

Ibn al-Haytham and psychophysics.  

PubMed

Persian scholar Ibn al-Haytham ('Alhazen') has rightly been credited with many advances in optics and vision science, but recent spurious claims that he is the 'founder of psychophysics' rest upon unsupported assertions, a conflation of psychophysics with the wider discipline of psychology, and semantic arguments over what it is to 'found' a school of thought. PMID:18546671

Aaen-Stockdale, Craig

2008-01-01

266

Primary (AL) Amyloidosis in Plasma Cell Disorders  

Microsoft Academic Search

Primary (AL) amyloidosis is the most common form of systemic amyloidosis. The morbidity arises from extra- cellular deposition of immunoglobulin light chain (LC) fibrils in major organs, such as the kidneys, heart, and bowel. Organ dysfunction contributes to a high mortal- ity and poor prognosis, with a median survival time of 1-2 years from diagnosis. Here, we present a 46-year-

Antonia M. S. Müller; Annette Geibel; Hartmut P. H. Neumann; Alexander Kühnemund; Annette Schmitt-Gräff; Joachim Böhm; Monika Engelhardt

267

Building the Base: Al Qaeda's Focoist Strategy  

Microsoft Academic Search

Al Qaeda has developed a coherent strategy for insurgent violence that has much in common with the focoism advocated by Che Guevara in the 1960s. In their strategic writing, explored here, key Islamist strategists stress the role of violence in creating revolution, and describe the export of committed fighters to focoist enclaves at the margins of enemy control. In contrast

Kenneth Payne

2011-01-01

268

Mechanical properties of Al metal foams  

Microsoft Academic Search

Pure Al foams, produced by a melt foaming method, were characterized by optical and electron microscopy and found to have a uniform microstructure. Their mechanical properties under compression were evaluated using a microtest apparatus in the Scanning Electron Microscopy (SEM) vacuum chamber while observing in situ the crack initiation. Their main mechanical properties, that is, the Young's modulus and the

D. P Papadopoulos; I. Ch Konstantinidis; N Papanastasiou; S Skolianos; H Lefakis; D. N Tsipas

2004-01-01

269

Lowest Ionization Potentials of Al2.  

National Technical Information Service (NTIS)

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 ...

C. W. Bauschlicher L. A. Barnes P. R. Taylor

1988-01-01

270

Kinematics of Disease Progression in Bulbar ALS  

PubMed Central

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 performance such as speaking rate and speech intelligibility. Movements of the lip and jaw were quantified with respect to their size (i.e., path distance measure), speed, and duration. The data revealed several changes in lip and jaw movement that coincided with ALS progression. In two out of three speakers, the changes in measures of path distance and speed anticipated the drop in speech intelligibility by approximately 3 months. With disease progression, increases in movement duration coincided with declines in speech intelligibility. Overall, the movement measures appeared to be sensitive to disease progression in ALS. Learning outcomes By the end of the manuscript, the reader should be able to: (1) describe the changes that occur in articulatory movements of the jaw and lower lip in ALS; (2) understand the relationship between physiologic measures of movement and speech intelligibility and speaking rate; (3) identify critical points in the disease progression and understand which quantitative measures reveal the state of the bulbar system at these time points.

Yunusova, Yana; Green, Jordan; Lindstrom, Mary; Ball, Laura; Pattee, Gary; Zinman, Lorne

2009-01-01

271

GaAlAsSb APD Optimization.  

National Technical Information Service (NTIS)

It has been demonstrated that avalanche gain can be obtained in GaAlSb avalanche photodiodes which exhibit ionization coefficient enhancement. These devices exhibit gain at relatively high impurity background density of 8-9 x 10 to the 15th power/cu cm. T...

R. Chin

1984-01-01

272

Synopsis of "Reply to Levitas et al."  

ERIC Educational Resources Information Center

|This synopsis of a reply by Wolf Wolfensberger to a critique by Levitas et al. (EC 609 743) notes extensive documentation supporting Wolfensberger's assertion that prescription psychoactive drugs are health destroying and life destroying. Issues of truth and of epistemology are identified as they apply to the treatment of these socially devalued…

O'Brien, John

1994-01-01

273

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

274

THE CREEP BEHAVIOUR OF MAGNOX AL80  

Microsoft Academic Search

An empirical secondary creep law for Magnox AL80 is deduced from ; selected data and compared with a creep law due to Ward. An activation energy ; for creep is obtained. All available experimental results are used to suggest ; that extrapolation of the selected points by the laws considered leads to ; optimistic results at higher stress levels. Proof''

L. R. T. Gardner; W. N. Miller

1962-01-01

275

Al Qaeda Refining a Failing Strategy.  

National Technical Information Service (NTIS)

Al Qaeda's inability to translate its post-9/11 approval in the Muslim world into a mass movement jihad against the West is prompting a search for new ways to regenerate lost momentum, but the group's inherent weaknesses are likely to prevent progress and...

M. J. Hart

2008-01-01

276

Mechanochemical synthesis and crystal structure of alpha'-AlD3 and alpha-AlD3.  

PubMed

AlD3 AlD3 was synthesized by ball milling of 3LiAlD4 + AlCl3. Planetary ball milling at room temperature resulted in a mixture of AlD3 (alpha and alpha') and Al in addition to LiCl, whereas cryomilling at 77 K resulted in only AlD3 and LiCl. The AlD3 obtained was a mixture of about 2/3alpha and 1/3alpha'. Alpha' was determined by powder neutron diffraction to take the beta-AlF3 structure with space group Cmcm and a = 6.470(3), b = 11.117(5), and c = 6.562(2) A. It is built up of corner-sharing AlD6 octahedra in an open structure with hexagonal holes of radius 3.9 A. Alpha' slowly decomposes during storage at 40 degrees C. Alpha-AlD3 is also described by a corner-sharing AlD6 network but in a more dense ReO3-type arrangement. Both AlD3 modifications have slightly shorter Al-D distances compared to Na3AlD6, Na2LiAlD6, and K2NaAlH6. PMID:17181228

Brinks, Hendrik W; Istad-Lem, Andreas; Hauback, Bjørn C

2006-12-28

277

Hydrogen Solubility in Al-bearing Perovskite  

NASA Astrophysics Data System (ADS)

It is generally accepted that silicate perovskite is the dominant mineral in the Earth's lower mantle. Previous studies have been completed to determine the physical and chemical characteristics of the pure end-member MgSiO3. Recent studies have shown that the addition of Al to MgSiO3 can have a significant effect on the material properties of the mineral, such as compressibility, and defect structure, as well as a great potential to dissolve water. We have synthesized Al-bearing perovskite samples under hydrous conditions in a multi-anvil apparatus at pressures ranging from 23-26 GPa and 1800oC. The starting materials consisted of brucite and silica powders mixed together and finely ground in a 1:1 molar ratio, with subsequent addition of Al2O3 powder at 2wt% intervals from 0%-6%. The mixed powders were tightly packed in Au capsules, housed in BN sleeves, and loaded into standard 8/3 multi-anvil assemblies. The experiments were brought to the appropriate pressure conditions for solubility of the different Al2O3 contents. The resulting perovskite crystals range in size from <20 microns to >100 microns in size. Their major element chemistry has been characterized by EPMA, and the H content of some samples has been measured by secondary ion mass spectrometry using a 6f Cameca ion microprobe and is substantial (>1200ppm in some samples). In this study, we correlate H content in the perovskites with Al concentration, and discussion follows on what effects this may have on potential substitution mechanisms, and correlated formation of oxygen vacancies, as well as water storage in the mantle, oxygen diffusion, and the potential of an oxygen ionic diffusion contribution to electrical conductivity in the mantle.

Watson, H. C.; Krawczynski, M. J.; Fei, Y.

2005-12-01

278

Influence of Schottky drain contacts on the strained AlGaN barrier layer of AlGaN/AlN/GaN heterostructure field-effect transistors  

NASA Astrophysics Data System (ADS)

Rectangular Schottky drain AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with different gate contact areas and conventional AlGaN/AlN/GaN HFETs as control were both fabricated with same size. It was found there is a significant difference between Schottky drain AlGaN/AlN/GaN HFETs and the control group both in drain series resistance and in two-dimensional electron gas (2DEG) electron mobility in the gate—drain channel. We attribute this to the different influence of Ohmic drain contacts and Schottky drain contacts on the strained AlGaN barrier layer. For conventional AlGaN/AlN/GaN HFETs, annealing drain Ohmic contacts gives rise to a strain variation in the AlGaN barrier layer between the gate contacts and the drain contacts, and results in strong polarization Coulomb field scattering in this region. In Schottky drain AlGaN/AlN/GaN HFETs, the strain in the AlGaN barrier layer is distributed more regularly.

Cao, Zhi-Fang; Lin, Zhao-Jun; Lü, Yuan-Jie; Luan, Chong-Biao; Wang, Zhan-Guo

2013-04-01

279

The Heats of Formation of AlClF2 and AlCl2F from Subliming AlF3 in the Presence of AlCl3 Vapor.  

National Technical Information Service (NTIS)

The volatility of AlF3, which was measured between 1196 and 1256K by an entrainment method, was enhanced by the presence of AlCl3 vapor. When the AlCl3 was generated by subliming at 373 or 394K, the amount of sublimed AlF3 was observed to be from 1.7 to 7...

R. F. Krause T. B. Douglas

1968-01-01

280

Thermoelectric Powers of Cells With NaF-AlF3-Al2O3 Melts  

NASA Astrophysics Data System (ADS)

A thermodynamic description of the Peltier heat at the aluminum and the oxygen electrode in the system NaF-AlF3-Al2O3 is given. The thermoelectric power in melts with molar ratios n NaF/n AlF3 from 3.0 to 1.0, saturated with alumina are measured. Seebeck coefficients for molten fluoride electrolytes saturated with alumina, electrolytes that are relevant for aluminum electrowinning electrolysis cells, are reported. The results allow determinations of Peltier heats of aluminum, oxygen and carbon electrodes in NaF-AlF3 electrolytes saturated with alumina. For molar ratios of n NaF/n AlF3 between 2.6 and 1.2, there is a Peltier heating of the aluminum cathode. This heating is in the same order of magnitude as the electrolyte Joule heat, when the current density is 0.7 A cm-2. For molar ratio n NaF/n AlF3 equal to 1.0 the Peltier effect at the aluminum electrode approaches zero. From theoretical considerations we expect a drop also for molar ratio 3.0. For the anode we report a Peltier cooling that is larger than the heat produced by the anodic overvoltage, in melts with NaF/AlF3 molar ratio between 2.6 and 1.2 saturated with alumina.

Flem, Belinda E.; Xu, Qian; Kjelstrup, Signe; Sterten, Åsmund

2001-07-01

281

Segregation at Coherent Interphase Boundaries: The Case of Mg at Al/Al_3Sc  

NASA Astrophysics Data System (ADS)

Recent advances in experimental methods have made possible the measurement of compositional variations at internal interfaces with near atomic-scale resolution. The combined application of such characterization techniques with first-principles computations provides the basis for greatly expanded insight into the microscopic factors governing interfacial segregation in multicomponent systems. This talk will discuss the application of such a combined experimental/computational approach in a study of Mg in two-phase Al-Sc-Mg alloys. Three-dimensional atom-probe and high-resolution electron microscopy measurements show a pronounced segregation of Mg solute atoms at the coherent interface between fcc-based Al and Al_3Sc phases, correlated with a Mg-induced decrease in the degree of faceting of Al_3Sc precipitates. The origin of these observed effects is investigated through the application of first-principles thermodynamic calculations. A significant driving force for the equilibrium segregation of Mg to coherent Al/Al_3Sc interfaces is derived from these calculations, which is found to be primarily ``chemical" in origin. The extension of this work to related Al-alloy systems will be discussed.

Asta, M.; Marquis, E. A.; Seidman, D. N.; Woodward, C.; Ozolins, V.

2004-03-01

282

An Epidemiological Study of Cutaneous Leishmaniasis in Al-Jabal Al-Gharbi, Libya  

PubMed Central

Cutaneous leishmaniasis (CL) is an endemic parasitic infection in the Mediterranean region, including Libya and its Al-jabal Al-gharbi province. We aimed at studying the occupational relevance as well as other epidemiological aspects of CL. We investigated 140 CL cases who attended at Gharyan outpatient polyclinic during a period of 6 months in 2009. CL infection was clinically diagnosed and confirmed by demonstration of Leishmania parasites on smears from lesions. Our findings showed that males were more affected than females (P=0.04), and people above 10-years were more affected than younger ones (P=0.0001). A significant percent of CL cases belonged to Al-Kawasem subprovince (P=0.0001). Farm-related activities were the most frequent occupations among CL cases (P=0.04). In addition to farm workers, housewives and students are at risk groups since they are engaged at farm activities. Moreover, those who have occupations that require staying outdoors for a part of night, e.g., policemen, are also at risk. Compared to children, adult CL patients had multiple lesions (P=0.001) that were more prevalent in their upper and lower extremities than the face (P=0.0001). We conclude that CL is a major health problem in Al-jabal Al-gharbi province of Libya. The presence of rodents and sandflies makes it a suitable environment for Leishmania to spread in an endemic epidemiological pattern. Being engaged in farming activities or outdoor occupations increases the risk of infection. Various clinical patterns of CL suggest the presence of more than 1 species of Leishmania at Al-jabal Al-gharbi province. We propose that the 2 species responsible for CL in this area are L. major and L. tropica. Further investigations to identify the leishmanial species responsible for CL at Al-jabal Al-gharbi together with adoption of preventive and control programs are needed.

Abdellatif, Manal Z. M.; El-Mabrouk, Khamis

2013-01-01

283

Phase equilibria in the ternary Al-Sc-Mn system  

NASA Astrophysics Data System (ADS)

Optical microscopy, electron microprobe analysis, and electrical resistivity measurements are used to study Al-Sc-Mn alloys containing up to 3 at % Sc and to 2.5 at % Mn. The boundaries of the Al-based solid solution are determined at 640, 600, and 400°C, and the isothermal section of the Al-rich portion of the Al-Sc-Mn system at 640°C is constructed. The Al-based solid solution is found to be in equilibrium with the ScAl3 and MnAl6 phases.

Rokhlin, L. L.; Bochvar, N. R.; Lysova, E. V.; Leonova, N. P.; Korol'Kova, I. G.

2008-02-01

284

Aplicación de la teoría de valores extremos al gerenciamiento del riesgo  

Microsoft Academic Search

Los activos en los mercados emergentes se caracterizan por una distribución de sus retornos más leptocúrtica que la de sus pares en mercados desarrollados. En este contexto se han aplicado diversas técnicas basadas en la Teoría de Valores Extremos (EVT) a un gran número de activos locales, a efectos de calcular su Valor a Riesgo (VaR). Estos resultaron ser mucho

Miguel T. Delfiner; Matías A. Gutiérrez Girault

2002-01-01

285

Quantitative x-ray photoelectron spectroscopy study of Al/AlOx bilayers  

NASA Astrophysics Data System (ADS)

An x-ray photoelectron spectroscopy (XPS) analysis of Nb/Al wedge bilayers, oxidized by both plasma and natural oxidation, is reported. The main goal is to show that the oxidation state--i.e., O:(oxidize)Al ratio--, structure and thickness of the surface oxide layer, as well as the thickness of the metallic Al leftover, as functions of the oxidation procedure, can be quantitatively evaluated from the XPS spectra. This is relevant to the detailed characterization of the insulating barriers in (magnetic) tunnel junctions.

Batlle, Xavier; Hattink, Bart Jan; Labarta, Amilcar; Akerman, Johan J.; Escudero, Roberto; Schuller, Ivan K.

2002-06-01

286

Interdiffusion in Diffusion Couples: U-Mo v. Al and Al-Si  

Microsoft Academic Search

Interdiffusion and microstructural development in the U-Mo-Al system was examined using solid-tosolid diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo and U-12wt.%Mo vs. pure Al, annealed at 600°C for 24 hours. The influence of Si alloying addition (up to 5 wt.%) in Al on the interdiffusion microstructural development was also examined using solid-to-solid diffusion couples consisting of U-7wt.%Mo, U-10wt.%Mo and U-12wt.%Mo vs.

Jr. D. D. Keiser; E. Perez; B. Yao; Y. H. Sohn

2009-01-01

287

Phase equilibria in Al-rich Al-Sc-Cr alloys  

NASA Astrophysics Data System (ADS)

Phase equilibria in aluminum alloys containing up to 1.2 wt % Sc and 1.0 wt % Cr are studied by optical microscopy and differential thermal and electron microprobe analyses. Two vertical sections and the projection of liquidus surface have been constructed. The four-phase nonvariant equilibrium at a temperature of 656.5 ± 1°C is found to have a transition character. The Al-based solid solution is found to be in equilibrium only with the Al3Sc and Al7Cr binary phases.

Rokhlin, L. L.; Dobatkina, T. V.; Bochvar, N. R.

2007-02-01

288

On the crack growth resistance and strength of the B2 iron aluminides Fe-40Al, Fe-45Al, and Fe-10Ni-40Al (at. %)  

SciTech Connect

The crack growth resistance and yield strength of the B2 iron aluminides Fe-40Al, Fe-45Al, are Fe-10Ni-40Al (at. %) have been investigated at room temperature laboratory air. After fast cooling from 1273 K, Fe-45Al and Fe-10Ni-40Al are much stronger than Fe-40Al, and exhibit considerably lower crack growth resistance. The crack growth resistance decreases with decreasing crack propagation velocity. Low crack propagation velocities favor intergranular fracture, whereas high velocities can lead to significant contributions from transgranular fracture. Boron additions to Fe-40Al and Fe-10Ni-40Al improve the crack growth resistance, reduce its dependence on the crack propagation velocity, and cause the path to be predominantly transgranular. In a plot of fracture toughness versus yield strength, the properties of the iron aluminides are similar to those of typical aluminum alloys.

Schneibel, J.H.; Maziasz, P.J.

1994-09-01

289

Improved electrical properties in AlGaN/GaN heterostructures using AlN/GaN superlattice as a quasi-AlGaN barrier  

NASA Astrophysics Data System (ADS)

The authors report the electrical properties of two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures using AlN/GaN superlattices working as a quasi-AlGaN barrier layer. It is found that the electrical properties (2DEG mobility and sheet carrier density) in the quasi-AlGaN/GaN heterostructure are greatly improved compared to those in the conventional alloy-AlGaN/GaN one at the high Al composition more than 0.35. The improved 2DEG properties result in the reduction of the sheet resistance to as low as 172 ?/squarelg, which is extremely important for the high power and high frequency device application. Theoretical calculations clearly indicate that the quasi-AlGaN barrier plays an important role in enhancing the confinement of the carrier at the quasi-AlGaN/GaN interface.

Kawakami, Y.; Nakajima, A.; Shen, X. Q.; Piao, G.; Shimizu, M.; Okumura, H.

2007-06-01

290

The study of preparation of AlN powder  

Microsoft Academic Search

Highly purified fine AlN powder was synthesized with low oxygen content. The optimal raw materials were Al2O3 dehydrated from Al(OH)3, carbon black, and AlN seed crystal, and their weight proportion was 1:0.5:0.01, respectively. Appropriate addition of AlN seed crystals might make the product finer. The order of the reaction was zero whose rate constants were 0.23 mol\\/L-s at 1400°C and

D. F. Qian; Z. D. Xiong

1991-01-01

291

Magnetomechanical hysteresis damping in FeAl alloys  

Microsoft Academic Search

The magnetomechanical hysteresis damping of Fe-Al alloys has been investigated using a computer-controlled automatic inverted torsion pendulum. It has been shown that Al content and heat treatment have a significant effect on the magnetomechanical hysteresis damping of the alloys. The Fe-10.5 (at.%)Al alloy has an optimal damping capacity after it was air-cooled from 900°C and the Fe-Al alloys with 29(at.)%Al

Z. C. Zhou; Z. C. Shen; Z. Jiang; F. S. Han

2005-01-01

292

Internal friction of ?-TiAl alloys at high temperature  

Microsoft Academic Search

Intermetallic ?-TiAl based alloys of engineering interest with respect to high temperature applications are two-phase alloys consisting of ?-TiAl (ordered face-centered tetragonal structure) and ?2-Ti3Al (ordered hexagonal structure). For this investigation a ?-TiAl based alloy with a composition of Ti-46.4 at%Al-4 at% (Cr, Nb, Ta, B) was studied utilizing a low frequency subresonance apparatus at frequencies between 0.01 and 10

M Weller; A Chatterjee; G Haneczok; H Clemens

2000-01-01

293

Synthesis and oxidation resistance of TiAlSiN and multilayer TiAlSiN\\/CrAlN coating  

Microsoft Academic Search

Oxidation resistant is one main factor to investigate for protective coatings of cutting tool application. In addition the formation of multilayer structure can be an alternative in improving the oxidation resistance. The monolayer TiAlSiN and multilayer TiAlSiN\\/CrAlN coating was deposited by cathodic arc ion-plating (AIP) method and oxidation resistance was studied in the range of 800 to 1000 °C. TiAlSiN with

N. Fukumoto; H. Ezura; T. Suzuki

2009-01-01

294

The inhibition of the corrosion of Al, Al6061 and AlCu in chloride free aqueous media: I. Passivation in acid solutions  

Microsoft Academic Search

The electrochemical behaviour of Al, Al-6061 and Al-Cu was investigated in solutions of different pH. The inhibition of the corrosion processes occurring at the electrode\\/electrolyte interface in solutions of borate buffers (pH 2) was studied. Molybdates and dichromates show pronounced inhibition action which was investigated and discussed. X-ray photoelectron spectroscopy (XPS) experiments have shown that Al-Cu alloys have remarkable Cu

W. A. Badawy; F. M. Al-Kharafi

1997-01-01

295

Reaction between amorphous Si and crystalline Al in Al\\/Si and Si\\/Al bilayers: microstructural and thermodynamic analysis of layer exchange  

Microsoft Academic Search

Aluminium-induced crystallization of amorphous silicon (a-Si) in Al\\/Si and Si\\/Al bilayers was studied upon annealing at 250 °C by X-ray diffraction and Auger electron spectroscopy. The Al\\/a-Si bilayers and a-Si\\/Al bilayers were prepared by sputter deposition on single-crystal silicon wafers with a silicon-oxide film on top. During the isothermal annealing a layer-exchange process occurred in both types of bilayers. A

D. He; J. Y. Wang; E. J. Mittemeijer

2005-01-01

296

Reaction between amorphous Si and crystalline Al in Al\\/Si and Si\\/Al bilayers: microstructural and thermodynamic analysis of layer exchange  

Microsoft Academic Search

Aluminium-induced crystallization of amorphous silicon (a-Si) in Al\\/Si and Si\\/Al bilayers was studied upon annealing at 250 °C by X-ray diffraction and Auger electron spectroscopy. The Al\\/a-Si bilayers and a-Si\\/Al bilayers were prepared by sputter deposition on single-crystal silicon wafers with a silicon-oxide film on top. During the isothermal annealing a layer-exchange process occurred in both types of bilayers. A continuous

D. He; J. Y. Wang; E. J. Mittemeijer

2005-01-01

297

The effect of hot-rolling on chill-cast Al, Al2 wt % Ni and Al4 wt % Ni alloys  

Microsoft Academic Search

The effect of hot-rolling on the mechanical properties and microstructure of directionallysolidified hypoeutectic Al-Al3Ni alloys has been studied. Chill-cast hypoeutectic alloys were produced by casting into pre-heated mild-steel moulds placed on copper chills. The chill-cast Al-2 wt% Ni and Al-4 wt% Ni hypoeutectic alloys can be hot-rolled at 500‡ C to reductions of greater than 95%. Deformation is achieved by

F. S. J. Jabczynski; B. Cantor

1982-01-01

298

Nuclear Quadrupole Coupling and Crystal-Field Effects in the Cubic Intermetallic Compounds ErAl3, TmAl3, and YbAl3  

Microsoft Academic Search

The presence of a large nuclear quadrupole coupling of the Al nucleus, as measured with NMR, in the cubic rare-earth aluminum intermetallic compounds beta-ErAl3, TmAl3, and YbAl3 indicates that the net charges at the rare-earth and aluminum sites differ by as much as 3 to 4 unit charges. Data on the magnetic susceptibility and this result have been used to

H. W. de Wijn; A. M. van Diepen; K. H. Buschow

1970-01-01

299

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

300

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

NASA Astrophysics Data System (ADS)

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.

Garcés, Jorge E.; Bozzolo, Guillermo; Hofman, Gerard; Rest, Jeffrey

2007-02-01

301

Microstructural evolution and hardness of TiAl3 and TiAl2 phases on Ti-45Al-2Nb-2Mn-1B by plasma pack aluminizing  

NASA Astrophysics Data System (ADS)

Plasma pack aluminizing of Ti-45Al-2Nb-2Mn-1B forms TiAl3 and TiAl2 phases.The TiAl3 and TiAl2 phases contain Cu, Nb and Mn.TiAl3 and TiAl2 appear as blocky, needle type and round particles in a matrix of aluminum alloy.Microhardness of TiAl3 and TiAl2 phases is higher than the substrate.

Rastkar, Ahmad Reza; Parseh, Pejman; Darvishnia, Naser; Hadavi, Seyed Mohammad Mehdi

2013-07-01

302

Phase composition of Al-Rich Al-Sc-Cr-Zr alloys at 640, 600, and 500°C  

NASA Astrophysics Data System (ADS)

Metallographic and electron microprobe analyses and hardness and electrical resistivity measurements are used to study Al-rich Al-Sc-Cr-Zr alloys annealed and quenched from 640, 600, and 500°C. The boundaries of Al-based solid solution are determined; the Al-based solid solution is found to be in equilibrium with the CrAl7 compound and ScAl3- and ZrAl3-based phases, in which zirconium and scandium are dissolved, respectively. Sections of isothermal tetrahedra at 640, 600, and 500°C are constructed.

Rokhlin, L. L.; Bochvar, N. R.; Leonova, N. P.; Korol'Kova, I. G.

2011-05-01

303

Self-Separation of Sublimation-Grown AlN with AlSiN Buffer Layer  

NASA Astrophysics Data System (ADS)

AlN was grown by a sublimation method on 6H-SiC. We found the grown AlN layer is easily separated from the substrate when Si powder is added to the AlN source powder. The formation of AlSiN layer with the Si content of 15% at the AlN/6H-SiC interface was confirmed by energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). This AlSiN layer causes the separation of AlN.

Nishino, Katsushi; Nakauchi, Jun; Hayashi, Kotaro; Tsukihara, Masashi

2013-08-01

304

Accurate interatomic potentials for Ni, Al and Ni/sub 3/Al  

SciTech Connect

To obtain meaningful results from atomistic simulations of materials, the interatomic potentials must be capable of reproducing the thermodynamic properties of the system of interest. Pairwise potentials have known deficiencies that make them unsuitable for quantitative investigations of defective regions such as crack tips and free surfaces. Daw and Baskes (Phys. Rev. B 29, 6443 (1984)) have shown that including a local ''volume'' term for each atom gives the necessary many-body character without the severe computational dependence of explicit n-body potential terms. Using a similar approach, we have fit an interatomic potential to the Ni/sub 3/Al alloy system. This potential can treat diatomic Ni/sub 2/, diatomic Al/sub 2/, fcc Ni, fcc Al and L1/sub 2/ Ni/sub 3/Al on an equal footing. Details of the fitting procedure are presented, along with the calculation of some properties not included in the fit.

Voter, A.F.; Chen, Shao Ping

1986-01-01

305

Rapid Solidification Processing of Al3Ti and Al3Ti Plus Copper.  

National Technical Information Service (NTIS)

The development of advanced airframes and propulsion systems has generated significant research and development activity in the area of light weight, high temperature intermetallic alloys, e.g., alpha-two and gamma titanium aluminides. However, Al3Ti, an ...

H. Tyndall J. Benci J. Zanter W. F. Frazier

1990-01-01

306

Al Speciation in Silicate Melts: AlV a new Network Former?  

NASA Astrophysics Data System (ADS)

The first human glasses were made 3500 BC. It was essentially sodo-lime silicate glass. To improve the chemical resistance, the thermal properties and increase the viscosity it is interesting to add aluminum in these silicates. But what is the speciation of the aluminum and how it varies according to the chemical composition and to the temperature? The aluminum appears essentially in four or five fold coordination in glasses and melts melted. The proportion of [5]Al varies according to the alkaline or to the earth-alkaline content and to the temperature. We shall present in a first part the influence of the network-modifier on the proportion of [5]Al and then we shall present some new results of absorption of high-temperature using NMR and XANES spectroscopy at the Al K-edge. Finally, from glass transition temperature measurements we propose to explain that [5]Al can be a new network former.

Neuville, D. R.; Florian, P.; de Ligny, D.; Montouillout, V.; Massiot, D.

2009-05-01

307

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

NASA Astrophysics Data System (ADS)

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.

Jang, Pyungwoo; Shin, Seungchan; Jung, Chip-Sup; Kim, Kwang-Ho; Seomoon, Kyu

2013-04-01

308

Nonstatistical fluctuations for deep inelastic processes in {sup 27}Al+{sup 27}Al collisions  

SciTech Connect

The excitation functions (EFs) for different fragments produced in the {sup 27}Al+{sup 27}Al dissipative collisions have been measured in steps of 250 keV in the incident energy range 122-132 MeV. Deep inelastic processes have been selected by integrating events on a total kinetic energy loss window of 12 MeV between 20 and 32 MeV. Large fluctuations are observed in all the studied EFs. Large-channel cross-correlation coefficients confirm the nonstatistical origin of these fluctuations. The energy autocorrelation function (EAF) shows damped oscillation structure as expected when a dinuclear system with a lifetime [{tau}=(5.1{+-}2.1){center_dot}10{sup -21}s], similar with its revolution period (T=4.9{center_dot}10{sup -21}sec), is formed. From the periodicity of the EAF oscillations, information on the deformation of the {sup 27}Al+{sup 27}Al dinucleus is inferred.

Berceanu, I.; Duma, M.; Moisa, D.; Petrovici, M.; Pop, A.; Simion, V. [National Institute of Physics and Nuclear Engineering, P.O. Box MG-6, H-76900 Bucharest (Romania); Zoppo, A. Del [Istituto Nazionale di Fisica Nucleare, Laboratorio Nazionale del Sud, v. S. Sofia 44, I-95100, Catania (Italy); D'Erasmo, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, v. Amendola 173, I-70126 Bari (Italy); Dipartimento di Fisica, Universita di Bari, V. Amendola 173, I-70126, Bari (Italy); Imme, G.; Lanzano, G.; Pagano, A. [Istituto Nazionale di Fisica Nucleare and Dipartimento di Fisica, I-95129 Catania (Italy); Pantaleo, A. [Istituto Nazionale di Fisica Nucleare, Sezione di Bari, v. Amendola 173, I-70126 Bari (Italy); Raciti, G. [Istituto Nazionale di Fisica Nucleare, Laboratorio Nazionale del Sud, v. S. Sofia 44, I-95100, Catania (Italy); Dipartimento di Fisica, Universita di Catania, I-95129 Catania (Italy)

2006-08-15

309

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

310

Early stage of Al3Zr precipitation in a rapidly solidified Al-Cr-Zr alloy  

Microsoft Academic Search

Early stages of A13Zr precipitation have been studied in detail in the ternary Al-2.4 at.% Cr-1.1 at.% Zr alloy. A supersaturated solid solution of Zr in the asrapidly solidified state decomposes during subsequent heat treatment at 400°C. This decomposition leads to a homogeneous precipitation of very small Al3Zr (LI2) particles in the grain interior, but this homogeneous precipitation is not

H. Octor; S. Naka

1989-01-01

311

LP MOVPE growth and characterization of high Al content Al x Ga 1? x N epilayers  

Microsoft Academic Search

High quality AlxGa1?xN layers have been grown on sapphire (0001) by low pressure metalorganic vapour phase epitaxy (LP MOVPE) at 1180°C. The aluminum content covers a wide composition range varying from 0 to 65%. In order to ameliore the quality of these epilayers especially for high aluminum content (XsAl >0.35), growth conditions are carefully optimized. The growth rate of AlGaN

C. Touzi; F. Omnès; B. El Jani; P. Gibart

2005-01-01

312

Experimental study of through-depth residual stress in explosive welded Al–Cu–Al multilayer  

Microsoft Academic Search

Explosive welded multi-layers sheet metals are widely used in recent years. Evaluation of residual stresses of this new merging material is necessary for better understanding of its mechanical behavior. In this paper, incremental hole-drilling (IHD) is used to measure through-depth non-uniform residual stress gradient in explosive welded Al–Cu–Al multilayers. At first, the multilayer sheets at two different initial thicknesses were

M. Sedighi; M. Honarpisheh

313

Experimental studies on the ignition of single Ni\\/Al, Fe\\/Al, and Ti particles  

Microsoft Academic Search

The work presented here focuses on the ignition of single Ni- and Fe-coated Al particles in pure CO2 and Ar atmospheres and Ti particles in O2\\/N2 and O2\\/Ar environments. The importance of studying Ni- and Fe-coated Al particles is related to their potential use in propulsion and materials synthesis applications. Meanwhile, Ti combustion may be utilized to eliminate hazardous chemical

Timothy Al Andrzejak

2007-01-01

314

Corrosion Behavior of Twin-Roll Cast Al-Mg and Al-Mg-Si Alloys  

Microsoft Academic Search

AlMg and AlMgSi alloys are used for automotive applications, where a good corrosion resistance is required. Recently, there has been a growing interest in using strip casting as a method to produce low-cost aluminum sheet for automotive applications. The present work was undertaken to investigate the corrosion behavior of twin-roll cast AA5754 and AA6016 sheet for panel applications, on the

Feriha Birol; Yucel Birol

2004-01-01

315

Damage and ductility of particulate and short-fibre Al?Al 2O 3 composites  

Microsoft Academic Search

The mechanical behaviour of 2014 and 6061 Al-alloy composites is investigated as a function of matrix treatment (T4 and T6 temper) and reinforcement shape (Al2O3 short fibres and particulates). Comparisons are carried out amongst the composites and with the corresponding unreinforced alloys and are mainly focused on the attained strength and ductility levels as influenced by damage accumulation and fracture

M. Vedani; E. Gariboldi

1996-01-01

316

An Approximation of Action Theories of AL \\\\mathcal{AL} and Its Application to Conformant Planning  

Microsoft Academic Search

\\u000a In this paper we generalize the notion of approximation of action theories introduced in [13,26]. We introduce a logic programming\\u000a based method for constructing approximation of action theories of AL\\\\mathcal{AL} and prove its soundness. We describe an approximation based conformant planner and compare its performance with other state-of-the-art\\u000a conformant planners.

Tran Cao Son; Phan Huy Tu; Michael Gelfond; A. Ricardo Morales

317

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

318

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 die casting (HPDC). In this article, Al alloy AlSi7Mg and Mg alloys AZ91 and AM60 were cast into tensile test bars using cold-chamber (cc) HPDC. Microstructural characterization revealed that externally solidified crystals (ESCs) are not necessary for defect band formation, and that defect bands

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

2007-01-01

319

PVD Coating of Mg–AZ31 by Thin Layer of Al and Al–Si  

Microsoft Academic Search

Although magnesium alloys have the advantage of high specific strength, they have poor atmospheric corrosion resistance. An\\u000a important method of improving the corrosion resistance is by applying a coating layer. In this work, the physical vapor deposition\\u000a (PVD) technique is used for coating a magnesium (Mg) AZ31 sheet substrate with a thin layer of high purity aluminum (Al) and\\u000a Al–12.6%

Mohamed A. Taha; Nahed A. El-Mahallawy; Rawia M. Hammouda; Sherif I. Nassef

2010-01-01

320

High-speed InGaAlAs\\/InAlAs multiple quantum well optical modulators  

Microsoft Academic Search

High-speed modulation over 22 GHz for waveguided InGaAlAs\\/InAlAs multiple quantum well (MQW) optical modulators is described. A large on\\/off ratio of over 25 dB is demonstrated with a low-drive voltage (6 V) operating in the 1.55-?m wavelength region. The design and characteristics of MQW p-i-n modulators are discussed. The causes of large-insertion loss and the required drive voltage bandwidth figure

Koichi Wakita; Isamu Kotaka; Osamu Mitomi; Hiromitsu Asai; Yuichi Kawamura; Mitsuru Naganuma

1990-01-01

321

Differential corticospinal tract degeneration in homozygous ‘D90A’ SOD1 ALS and sporadic ALS  

Microsoft Academic Search

BackgroundThe homogeneous genotype and stereotyped phenotype of a unique familial form of amyotrophic lateral sclerosis (ALS) (patients homozygous for aspartate-to-alanine mutations in codon 90 (homD90A) superoxide dismutase 1) provides an ideal model for studying genotype\\/phenotype interactions and pathological features compared with heterogeneous apparently sporadic ALS. The authors aimed to use diffusion tensor tractography to quantify and compare changes in the

C R V Blain; S Brunton; V C Williams; A Leemans; M R Turner; P M Andersen; M Catani; B R Stanton; J Ganesalingham; D K Jones; S C R Williams; P N Leigh; A Simmons

2011-01-01

322

Tensile properties and fracture characteristics of ECAP-processed Al and Al-Cu alloys  

Microsoft Academic Search

In the present paper, billets of pure Al, and cast-homogenized Al-2 wt.%, 3 wt.%, and 5 wt.% Cu alloys were successfully processed\\u000a by equal channel angular pressing (ECAP) up to 10 passes without fracture at room temperature using a die with a channel angle\\u000a of 110°. Giant strains imposed on workpieces lead to extreme dislocation densities, microstructural refinement, and finally

Mohamed Ibrahim Abd El Aal; Nahed El Mahallawy; Farouk A. Shehata; Mohamed Abd El Hameed; Eun Yoo Yoon; Jung Hwan Lee; Hyoung Seop Kim

2010-01-01

323

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

324

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

325

Impact of superbends at the ALS  

SciTech Connect

To satisfy a demand for high energy, high brightness x-ray sources at the Advanced Light Source (ALS), a plan is in place to replace three 1.3 Tesla normal conducting bending magnets with three 5 Tesla superconducting magnets (superbends) in the year 2001. In this paper they discuss the impact of the superbends on the ALS beam parameters and particle dynamics. In particular they show the effect on the emittance, energy spread, and lifetime. They find that by adjusting the dispersion to be positive in the straight section they are able to largely restore the horizontal emittance. The vertical emittance can be adjusted independently to control the lifetime. The particle dynamics are investigated through particle tracking with a frequency analysis postprocessor. They find that by placing the three superbends symmetrically around the ring there is ample dynamic aperture for injection and lifetime.

Nishimura, H.; Robin, D.

1999-03-19

326

Forging of FeAl intermetallic compounds  

SciTech Connect

Much activity has been concentrated on the development of intermetallic compounds with the aim of improving tensile ductility, fracture toughness and high notch sensitivity in order to develop an attractive combination of properties for high and low temperature applications. This paper reports experience in processing and forging of FeAl intermetallic of B2 type. During the experiments two different temperatures were employed, and the specimens were forged after annealing in air, 10{sup {minus}2} torr vacuum and argon. From the results it was learned that annealing FeAl in argon atmosphere prior to forging resulted in better deformation behavior than for the other two environments. For the higher forging temperature used in the experiments (700C), the as-cast microstructure becomes partially recrystallized.

Flores, O.; Juarez, J.; Campillo, B.; Martinez, L. [UNAM, Cuernavaca (Mexico). Lab. de Cuernavaca; Schneibel, J.H. [Oak Ridge National Lab., TN (United States)

1994-09-01

327

Annealing twins in nominally pure Al  

SciTech Connect

Classic examples of annealing twins were observed in Al which was sufficiently pure due to Fe precipitation such that continuous recrystallization could occur. The twin formation at triple junctions is due to energy reduction on both sides bounding the twinned grain. The low frequency of such twins illustrates that twin boundary energy in Al is indeed comparable to large angle boundary energy. The observation of many {Sigma}3 oriented grains without readily distinguishable planar boundaries supports this conclusion. The formation of parallel twins is assisted by stored work whereby the dislocated structure is eliminated by the migration of incoherent twin boundaries. If the bounding recrystallized region envelops the twin band, the driving force is lost and the twin band shrinks.

Li, J.; Saimoto, S. [Queen`s Univ., Kingston, Ontario (Canada). Dept. of Materials and Metallurgical Engineering; Seki, F.; Itoh, K. [Univ. of Tokyo (Japan). Dept. of Materials Science; Kamijo, T. [Yokohama National Univ. (Japan). Dept. of Mechanical Engineering

1997-06-01

328

Observable Proxies For 26 Al Enhancement  

SciTech Connect

We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}Al in supernova ejecta and stellar systems. Using four progenitors we explore a range of 1D explosions at different energies and an asymmetric 3D explosion. We find that the most reliable indicator of the presence of {sup 26}Al in unmixed ejecta is a very low S/Si ratio ({approx} 0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multi wavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

Fryer, Christopher L [Los Alamos National Laboratory; Young, Patrick A [Los Alamos National Laboratory; Ellinger, Carola I [ASU; Arnett, William D [UNIV ARIZONA

2008-01-01

329

Fabrication and characterization of TiAl\\/Ti 3 Al-based intermetallic composites (IMCs) reinforced with ceramic particles  

Microsoft Academic Search

Purpose: The purpose of the paper is to fabricate and characterise TiAl\\/Ti3Al-based intermetallic composites (IMCs) reinforced with ceramic particles. Design\\/methodology\\/approach: Composites were formulated by blending commercially available powders of either TiAl or Ti3Al (technical grade with traces of Al and Ti) with ceramic powders (B4C, TiC or TiB2) in appropriate amounts to create titanium aluminide-based matrices with 10, 20, 30,

V. Kevorkijan; S. D. Škapin

330

Characterization of Al 2O 3–Al nano-composite powder prepared by a wet chemical method  

Microsoft Academic Search

A wet chemical method was used to prepare Al2O3-coated Al nano-size-composite powders using Al, aluminum nitrate and ammonia as the starting materials. TEM, SEM, TG\\/DSC, zeta potential, XPS, X-ray were used to characterize the composite powders. Results showed that a uniform thin Al(OH)3 layer can formed on the surface of Al particles. After calcined at 1000°C for 2h, the thin

Hong-xia Lu; Jie Hu; Chang-ping Chen; Hong-wei Sun; Xing Hu; De-lin Yang

2005-01-01

331

Kinetics of NiAl3 and Ni2Al3 phase growth on lateral diffusion couples  

Microsoft Academic Search

The phase formation of NiAl3 and Ni2Al3 is studied on lateral diffusion couples of an Al-rich source on a Ni thin film at temperatures from 375 to 500 °C. Analytical electron microscopy is used to determine the crystal structures, chemical compositions, and the widths of growing phases. Simultaneous growth of NiAl3 and Ni2Al3 is observed at 375 and 450 °C.

Joyce C. Liu; J. W. Mayer; J. C. Barbour

1988-01-01

332

Hydrogen embrittlement of Fe 3Al alloys  

Microsoft Academic Search

The tensile and fatigue crack growth behavior of two Fe?Al alloys, FA-129 and FAP-Y, are described. FA-129 is an ordered intermetallic while FAP-Y is disordered. The intermetallic is embrittled by both laboratory air and by hydrogen gas, while FAP-Y is embrittled only by hydrogen gas. Fractographic features as well as dislocation substructures for both alloys are described. Oxygen is found

A. Castagna; N. S. Stoloff

1995-01-01

333

Ignition Behavior of ?-AlH3  

Microsoft Academic Search

An experimental investigation on the ignition behavior of ?-Aluminum Hydride (?-AlH3) has been conducted. The ignition characteristics were determined through the use of two separate modified T-jump experiments. In each experiment, a small amount of material was placed onto a platinum wire, which was heated rapidly through resistive heating. As a result both ignition and hydrogen release temperatures were studied

G. Young; N. Piekiel; S. Chowdhury; M. R. Zachariah

2010-01-01

334

Repetitive transcranial magnetic stimulation for ALS  

Microsoft Academic Search

Repetitive transcranial magnetic stimulation (rTMS) of brain can modulate cortical neurotransmission, a novel paradigm of repetitive stimulation termed continuous theta-burst stimulation (cTBS) produces a pronounced and prolonged suppression of motor cortex excitability. The aim of this preliminary study was to investigate whether cTBS of motor cortex could have any beneficial effect in patients with amyotrophic lateral sclerosis (ALS). We performed

Vincenzo Di Lazzaro; Michele Dileone; Fabio Pilato; Paolo Profice; Federico Ranieri; Gabriella Musumeci; Francesco Angelucci; Mario Sabatelli; Pietro A. Tonali

2006-01-01

335

Indentation Tests on Al Matrix Syntactic Foams  

Microsoft Academic Search

This paper investigates mechanical response of Al matrix syntactic foams manufactured by pressure infiltration casting under\\u000a indentation test. Syntactic foams with ceramic microspheres of three different particle sizes and inner structures were manufactured\\u000a and tested. Because the hollow microspheres are stronger than the porous ones, the syntactic foam with hollow microspheres\\u000a has a higher compressive strength than that of the

X. F. Tao; G. K. Schleyer; Y. Y. Zhao

336

The heat treatment of AL9 alloy  

Microsoft Academic Search

1.Optimal mechanical properties are produced in heat treated AL9 alloy specimens by hardening for four hours and aging at 170 and 185°C for four to six, and two to four hours, respectively.2.The mechanical properties of specimens in accordance with the provisions of State Standard 2685-53 may be obtained by using a shortened hardening cycle which comprises a one to two

P. A. Parkhutik; A. F. Zakharova

1962-01-01

337

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

338

Effects of Al content on grain growth of solid solution (Ti,Al)N films  

SciTech Connect

Substitutional solid solution (Ti{sub 1-x}Al{sub x})N films with different Al contents (0{<=}x{<=}0.41) were deposited onto unheated Si(100) substrates by reactive unbalanced close-field magnetron sputtering in an Ar-N{sub 2} gas mixture. The effect of Al atomic concentration on the sizes of crystal grains during deposition was investigated. X-ray diffraction analysis revealed that the incorporated Al atoms had an obvious impact on the grain growth of (Ti{sub 1-x}Al{sub x})N films and the average crystal grain size showed an exponential decay with Al atomic concentration. A phenomenological model was proposed to analyze this solute-drag effect occurring during film deposition. It was found that the presence of solute drag in normal grain growth resulted in a low kinetic growth exponent, and the exponential decay in average grain size with solute atomic concentration could be reproduced in our calculations.

Liu, Z.-J.; Shen, Y.G. [Department of Manufacturing Engineering and Engineering Management, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2006-01-15

339

Hot ductility of Al-Mg and Al-Mg-Y alloys impaired by trace sodium  

SciTech Connect

Effect of trace amounts of impurity sodium on hot ductility of Al-5%Mg and Al-5%Mg-0.04%Y alloys was examined at temperatures ranging from 200 C to 400 C. The embrittlement appears in the Al-Mg-Y alloy containing 0.60 ppm sodium but does not in the Al-Mg-Y alloy containing 0.06 ppm sodium. The embrittlement in the ternary alloy is caused only by sodium. On the other hand, the embrittlement appears in the Al-Mg alloy containing 0.61 ppm sodium as well as in the Al-Mg alloy containing 0.06 ppm sodium. The former is caused by both sodium and hydrogen, and the latter by hydrogen alone. It was found that sodium on the order of 0.1 ppm is enough to cause the embrittlement dependent on the grain size. It is concluded that the effect of both impurity elements must be eliminated to inhibit the embrittlement.

Okada, Hiroshi; Kanno, Motohiro [Univ. of Tokyo (Japan). Dept. of Materials Science

1997-09-15

340

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)

1996-04-01

341

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

342

Anomalous phonon properties in the silicide superconductors CaAlSi and SrAlSi  

NASA Astrophysics Data System (ADS)

Lattice-dynamical properties of CaAlSi and SrAlSi with a similar layer structure to MgB2 have been first investigated by both Raman-scattering and ab initio calculations. All Raman-active phonons with E' symmetry have been clearly observed for both compounds. Their line shapes are asymmetric but their linewidths are ˜10cm-1 , which is very narrower than that of MgB2 . In addition to the Raman-active modes, several extra peaks have been observed below 160cm-1 . These low-energy extra modes can be assigned to the out-of-plane vibrations of Al perpendicular to Al-Si basal plane. Since these peak intensities are strongly affected by the incident energy (resonance Raman process), the electronic state is important for them. Moreover, in both crystals of CaAlSi and SrAlSi, we point out the energy difference for the different propagation directions along the c axis and the c plane, in spite of the very close wave vector to the Brillouin-zone center. This energy difference cannot be explained by a usual Raman-scattering scenario at this stage.

Kuroiwa, S.; Hasegawa, T.; Kondo, T.; Ogita, N.; Udagawa, M.; Akimitsu, J.

2008-11-01

343

Thermodynamic properties of the MgAl2O4-MnAl2O4 spinel solid solution  

NASA Astrophysics Data System (ADS)

The thermodynamic properties of the MgAl2O4-MnAl2O4 system are required for calculating the deoxidation equilibrium of molten iron and nickel containing magnesium, manganese, and aluminum. The thermodynamic properties of the MgAl2O4-MnAl2O4 spinel solid solution have been determined by equilibrating it with silver at known oxygen partial pressures. The free energy of formation of MnAl2O4 from its oxide components at 1673 and 1823 K was found to be -30.6 and -28.2 kJ/mol, respectively. It was observed that the MgAl2O4-MnAl2O4 spinel solid solution exhibited small negative deviations from ideal behavior at 1673 and 1823 K. The excess partial free energies of MgAl2O4,G_{MgAl_2 O_4 }^E , and MnAl2O4,G_{MnAl_2 O_4 }^E , at 1673 and 1823 K are expressed as G 11663_2007_Article_BF02654103_TeX2GIFE1.gif G_{MnAl_2 O_4 }^E = - 32.84(1 - X_{MnAl_2 O_4 } )^2 + 69.66(1 - X_{MnAl_2 O_4 } )^3 - 58.57(1 - X_{MnAl_2 O_4 } )^4 {text{ }}at{text{ 1823 K}} 11663_2007_Article_BF02654103_TeX2GIFE2.gif G_{MnAl_2 O_4 }^E = - 43.69(1 - X_{MnAl_2 O_4 } )^2 + 100.53(1 - X_{MnAl_2 O_4 } )^3 - 87.63(1 - X_{MnAl_2 O_4 } )^4 {text{ }}at{text{ 1673 K}} 11663_2007_Article_BF02654103_TeX2GIFE3.gif G_{MgAl_2 O_4 }^E = - 45.49(1 - X_{MgAl_2 O_4 } )^2 + 86.53(1 - X_{MgAl_2 O_4 } )^3 - 58.57(1 - X_{MgAl_2 O_4 } )^4 {text{ }}at{text{ 1823 K}} 11663_2007_Article_BF02654103_TeX2GIFE4.gif G_{MgAl_2 O_4 }^E = - 68.16(1 - X_{MgAl_2 O_4 } )^2 + 133.15(1 - X_{MgAl_2 O_4 } )^3 - 87.63(1 - X_{MgAl_2 O_4 } )^4 {text{ }}at{text{ 1673 K}}

Zhao, Yihong; Morita, Kazuki; Sano, Nobuo

1995-10-01

344

?-Synuclein Modification in an ALS Animal Model  

PubMed Central

Amyotrophic lateral sclerosis (ALS) is a progressively paralytic neurodegenerative disease that can be caused by mutations in Cu/Zn-superoxide dismutase 1 (SOD1). Transgenic mice that overexpress mutant SOD1 develop paralysis and accumulate aggregates of mutant protein in the brainstem and spinal cord. Bee venom (BV), which is also known as apitoxin, is extracted from honeybees and is commonly used in oriental medicine for the treatment of chronic rheumatoid arthritis and osteoarthritis. The purpose of the present study was to determine whether BV affects misfolded protein aggregates such as alpha-synuclein, which is a known pathological marker in Parkinson disease, and ubiquitin-proteasomal activity in hSOD1G93A mutant mice. BV was bilaterally administered into a 98-day-old hSOD1G93A animal model. We found that BV-treated hSOD1G93A transgenic mice showed reduced detergent-insoluble polymerization and phosphorylation of ?-synuclein. Furthermore, phosphorylated or nitrated ?-synuclein was significantly reduced in the spinal cords and brainstems of BV-treated hSOD1G93A mice and reduced proteasomal activity was revealed in the brainstems of BV-treated symptomatic hSOD1G93A. From these findings, we suggest that BV treatment attenuates the dysfunction of the ubiquitin-proteasomal system in a symptomatic hSOD1G93A ALS model and may help to slow motor neuron loss caused by misfolded protein aggregates in ALS models.

Yang, Eun Jin; Choi, Sun-Mi

2013-01-01

345

AlN antiresonant layer ARROW waveguides  

NASA Astrophysics Data System (ADS)

Aluminum Nitride (AlN) is a wide band gap III-V semiconductor material often used for optical applications due to its transparency and high refractive index. We have produced and characterized AlN thin films by reactive r.f. magnetron sputtering in different Ar-N2 atmospheres in order to verify the best gaseous concentration to be utilized as anti-resonant layer in ARROW waveguides. The corresponding films were characterized by Fourier transform infrared spectroscopy (FTIR), Rutherford backscattering spectroscopy (RBS), Ellipsometry and visible optical absorption. The AlN properties did not varied significantly between the films deposited with 20 and 70 sccm of N2, most of the variations occurred for films deposited with 18 sccm of N2 or below. The film deposited with 20 sccm was selected to be used as the first ARROW layer in the fabricated waveguides. Two routines were used to design the waveguides parameters, the transfer matrix method (TMM) and the semi-vectorial non-uniform finite difference method (NU-FDM). Attenuation as low as 3.5dB/cm was obtained for a 7 ?m wide waveguide.

Pelegrini, M. V.; Carvalho, D. O.; Alayo, M. I.; Pereyra, I.

2010-02-01

346

An ALS (Advanced Light Source) handbook  

SciTech Connect

This booklet aims to provide the prospective user of the Advanced Light Source with a concise description of the radiation a researcher might expect at his or her experimental station. The focus is therefore on the characteristics of the light that emerges from insertion devices and bending magnets and on how components of the beam lines further alter the properties of the radiation. The specifications and operating parameters of the ALS injection system and storage ring are of only peripheral interest. To this end, Sections 3 and 5 and most of Section 4 are devoted to summary presentations, by means of performance plots and tabular compilations, of radiation characteristics at the ALS--spectral brightness, flux, coherent power, resolution, time structure, etc.--assuming a representative set of four undulators and one wiggler and a corresponding set of five beam lines. As a complement to these performance summaries, Section 1 is a general introductory discussion of synchrotron radiation and the ALS, and Section 2 provides a compendious introduction to the characteristics of synchrotron radiation from bending magnets, wigglers, and undulators. In addition, Section 4 briefly introduces the theory of diffraction grating and crystal monochromators. 15 refs., 28 figs., 5 tabs.

Not Available

1988-11-01

347

ALS motor phenotype heterogeneity, focality, and spread  

PubMed Central

Heterogeneity of motor phenotypes is a clinically well-recognized fundamental aspect of amyotrophic lateral sclerosis (ALS) and is determined by variability of 3 independent primary attributes: body region of onset; relative mix of upper motor neuron (UMN) and lower motor neuron (LMN) deficits; and rate of progression. Motor phenotypes are determined by the anatomy of the underlying neuropathology and the common defining elements underlying their heterogeneity are that motor neuron degeneration is fundamentally a focal process and that it spreads contiguously through the 3-dimensional anatomy of the UMN and LMN levels, thus causing seemingly complex and varied clinical manifestations. This suggests motor neuron degeneration in ALS is in actuality a very orderly and actively propagating process and that fundamental molecular mechanisms may be uniform and their chief properties deduced. This also suggests opportunities for translational research to seek pathobiology directly in the less affected regions of the nervous system. GLOSSARY ALS = amyotrophic lateral sclerosis; FTD = frontotemporal dementia; LMN = lower motor neuron; UMN = upper motor neuron.

Ravits, John M.; La Spada, Albert R.

2009-01-01

348

KCAT, Xradia, ALS and APS Performance Summary  

SciTech Connect

At Lawrence Livermore National Laboratory (LLNL) particular emphasis is being placed on the nondestructive characterization (NDC) of components, subassemblies and assemblies of millimeter-size extent with micrometer-size features (mesoscale). These mesoscale objects include materials that vary widely in composition, density, geometry and embedded features. Characterizing these mesoscale objects is critical for corroborating the physics codes that underlie LLNL's Stockpile Stewardship mission. In this report we present results from our efforts to quantitatively characterize the performance of several x-ray systems in an effort to benchmark existing systems and to determine which systems may have the best potential for our mesoscale imaging needs. Several different x-ray digital radiography (DR) and computed tomography (CT) systems exist that may be applicable to our mesoscale object characterization requirements, including microfocus and synchrotron systems. The systems we have benchmarked include KCAT (LLNL developed) and Xradia {mu}XCT (Xradia, Inc., Concord, CA), both microfocus systems, and Beamline 1-ID at the Advance Photon Source (APS) and the Tomography Beamline at the Advanced Light Source (ALS), both synchrotron based systems. The ALS Tomography Beamline is a new installation, and the data presented and analyzed here is some of the first to be acquired at the facility. It is important to note that the ALS system had not yet been optimized at the time we acquired data. Results for each of these systems has been independently documented elsewhere. In this report we summarize and compare the characterization results for these systems.

Waters, A; Martz, H; Brown, W

2004-09-30

349

Devitrification of Al-Y-Ni Glasses  

SciTech Connect

Crystallization of gas-atomized Al-4.3Y-3.8Ni alloy powder during consolidation has been studied ex-situ in a transmission electron microscope using high-resolution lattice imaging together with the image simulations, selected-area diffraction and energy-dispersive X-ray spectrometry experiments. The as-atomized powder is predominantly amorphous but some particles others show evidence of decomposition. On the application of heat and pressure two types of decomposition product are formed initially; equiaxed nanoscale {alpha}-Al grains embedded in an amorphous matrix, and dendritic aluminum grains containing complex ordered structures. The ordered structures in the {alpha}-Al were identified as Guinier-Preston like zones: thin sheets of solute rich material parallel to {l_brace}100{r_brace} and {l_brace}110{r_brace} aluminum planes with ordered cubic symmetry. Amorphous and micro-crystalline phases are in between the aluminum-rich regions. The second and third stages of crystallization involve the conversion of these ordered phases and embryonic precipitates to the better-known binary and ternary compounds.

Vasiliev, A. L. [Institute of Crystallography Russian Academy of Sciences, Leninskij pr., 59, Moscow (Russian Federation); Aindow, M. [Institute of Materials Science, University of Connecticut, Storrs, CT 06269-3136 (United States)

2008-04-10

350

Influence of Al-acetylacetonate addition on the CVD deposition of Al 2O 3 (reaction gas: AlCl 3\\/CO 2\\/H 2)  

Microsoft Academic Search

In order to decrease the grain size of Al2O3 coatings deposited from the usual AlCl3\\/CO3\\/H2 reaction gas mixture, Al-acetylacetonate (Al-acac) was added in the concentrations of 1000, 10000 and 50000 mol-ppm (relative to mol A1C13). TiC-coated cemented carbide substrates were used.Extremely fine-grained A12O3 coatings were obtained by adding 50 000 mol-ppm Al-acac. At a total pressure of 50 torr this

M. Danzinger; R. Haubner; B. Lux

1996-01-01

351

Enhanced Light Extraction in AlInGaN UV Light-Emitting Diodes by an Embedded AlN/AlGaN Distributed Bragg Reflector  

NASA Astrophysics Data System (ADS)

A novel kind of AlInGaN ultraviolet (UV) light-emitting diode (LED) with an embedded AlN/Al0.3Ga0.7N distributed Bragg reflector (DBR) is proposed to enhance light extraction efficiency (LEE). The simulation technique we adopt to calculate the LEE of LEDs is based on the theory of spontaneous emission in a layered medium, the well-known mode-matching technique and the scattering matrix approach. The AlN/Al0.3Ga0.7N DBR was intentionally designed to have peak reflectivity at the LED emission wavelength and the optical properties of the DBR were simulated by using the transfer matrix method. A high LEE of 45.7% at 370 nm wavelength was predicted for a proposed AlInGaN UV LED consisting of 24 periods of the AlN/Al0.3Ga0.7N DBR, which is 1.5 times of that of the conventional AlInGaN UV LED. The investigation shows that the AlN/Al0.3Ga0.7N DBR grown on GaN templates with sapphire as a substrate by MOCVD can enhance the LEE effectively and would be very promising for the fabrication of high performance GaN-based UV LEDs.

Liu, Hui; Zhao, Heng; Hou, Jin; Liu, Dan; Gao, Yi-Hua

2012-10-01

352

Reduced electron back-injection in Al2O3/AlOx/Al2O3/graphene charge-trap memory devices  

NASA Astrophysics Data System (ADS)

A graphene charge-trap memory is devised using a single-layer graphene channel with an Al2O3/AlOx/Al2O3 oxide stack, where the ion-bombarded AlOx layer is intentionally added to create an abundance of charge-trap sites. The low dielectric constant of AlOx compared to Al2O3 reduces the potential drop in the control oxide Al2O3 and suppresses the electron back-injection from the gate to the charge-storage layer, allowing the memory window of the device to be further extended. This shows that the usage of a lower dielectric constant in the charge-storage layer compared to that of the control oxide layer improves the memory performance for graphene charge-trap memories.

Lee, Sejoon; Song, Emil B.; Min Kim, Sung; Lee, Youngmin; Seo, David H.; Seo, Sunae; Wang, Kang L.

2012-12-01

353

Elevated temperature wear of Al6061 and Al6061-20%Al{sub 2}O{sub 3}  

SciTech Connect

Both current and potential applications of particulate reinforced aluminum alloys involve components which are required to operate under sliding contact conditions at elevated temperatures. Examples include brake rotors, piston and cylinder liners in automotive engines where operating temperatures can reach 0.5--0.8 of the melting temperature of the matrix alloy. For this reason, study of the high temperature wear resistance of aluminum alloys reinforced by Al{sub 2}O{sub 3} or SiC particles is important. These studies are also of interest for the problem of die wear during hot extrusion of aluminum matrix composites and to rationalize the process of frictional welding involved in joining of the composites. Although the room temperature tribological and mechanical behaviors of aluminum matrix composites have received considerable attention, their high temperature properties have only recently started being considered. It has been shown that Al-Si-Mg (A356) alloys with or without SiC particles show a transition from mild to severe wear when a critical temperature (at about 0.4 T{sub m}, where T{sub m} is the melting temperature of aluminum) is reached as a result of frictional heating under dry sliding conditions. In this work, high temperature wear of A16061 and A16061-20%Al{sub 2}O{sub 3} was studied at temperatures between 25--500 C. The microstructural changes that occurred during wear have been delineated in order to understand the wear mechanisms that operate at high temperatures.

Singh, J.; Alpas, A.T. [Univ. of Windsor, Ontario (Canada)

1995-04-01

354

Silver ionic and electronic conductivity in Ag9GaS6, Ag9AlS6, AgGaS2, AgAlS2, and AgAl5S8  

NASA Astrophysics Data System (ADS)

Silver ionic and electronic conductivity in phases in the Ag2S-M2S3, M = Al, Ga, systems have been investigated using dc methods with ionically reversible electrodes and ac methods. Measurements on the mixed conductors Ag9GaS6 and the new phase Ag9AlS6, both with high silver ionic conductivity, the chalcopyrites AgGaS2 and AgAlS2, both with predominate silver ionic conductivity, and the mixed conducting spinel, AgAl5S8, are reported. In addition, a schematic version of the Ag2S-Al2S3 phase diagram is presented.

Hellstrom, E. E.; Huggins, R. A.

1980-11-01

355

Ti-Al-C MAX phases by aluminothermic reduction process  

Microsoft Academic Search

A new approach to synthesis of Ti2AlC-Ti3AlC2\\/Al2O3 compounds is developed based on thermite reaction in the TiO2-Al-C system. The effect of Al excess is also discussed. XRD analysis has proved that this parameter can be used to improve\\u000a the product purity, i.e., the amount of TiC in the final product. It has also been shown that, with increasing Al excess,

A. Hendaoui; D. Vrel; A. Amara; A. Benaldjia; P. Langlois

2008-01-01

356

AlN wafers fabricated by hydride vapor phase epitaxy  

SciTech Connect

The authors report on AlN wafers fabricated by hydride vapor phase epitaxy (HVPE). AlN thick layers were grown on Si substrates by HVPE. Growth rate was up to 60 microns per hour. After the growth of AlN layers, initial substrates were removed resulting in free-standing AlN wafers. The maximum thickness of AlN layer was about 1 mm. AlN free-standing single crystal wafers with a thickness ranging from 0.05 to 0.8 mm were studied by x-ray diffraction, transmission electron microscopy, optical absorption, and cathodoluminescence.

Nikolaev, A.; Nikitina, I.; Zubrilov, A.; Mynbaeva, M.; Melnik, Y.; Dmitriev, V.

2000-07-01

357

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

358

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

359

Characterization of Al2O3 coatings oxidized from Al with different proportion of seed crystals at a lower temperature  

NASA Astrophysics Data System (ADS)

Al layer with ?-Al2O3 seed crystals was prepared on the surface of 316L stainless steel (SS) by a double cathodes discharge technique, in which the mixed targets of pure Al doped with different proportions of ?-Al2O3 were used. Then, Al2O3 coatings were obtained after plasma oxidization at 580 °C. The phase composition, microstructure and morphology of the coatings were studied respectively by means of glancing-angle (1°) X-ray diffractometry (GAXRD) and scanning electron microscopy (SEM). Furthermore, the bonding force and corrosion resistance of the coatings were measured. The results indicated that ?-Al2O3 nucleated and grew surrounding the seed crystals as the Volmer-Weber Mode. The Al2O3 coating was compact, performing a good corrosion resistance and metallurgical bonding. The inducing effects of ?-Al2O3 with different fractions were discussed. ?-Al2O3 (5.5 wt.%) was distributed in the Al layer when the target possessing 10% ?-Al2O3 was used. After plasma oxidation, 65.54 wt.% ?-Al2O3 was obtained which was 10.34% more than that obtained by the oxidation of pure Al at the same condition. However, the inducing effects became weak with the further increment of content of ?-Al2O3 seed crystals.

Wang, Chen; Lin, Yuebin; He, Fei; Luo, Xinyi; Tao, Jie

2013-10-01

360

First-principles studies of Al-Ni intermetallic compounds  

SciTech Connect

The structural properties, heats of formation, elastic properties, and electronic structures of Al-Ni intermetallic compounds are analyzed here in detail by using density functional theory. Higher calculated absolute values of heats of formation indicate a very strong chemical interaction between Al and Ni for all Al-Ni intermetallic compounds. According to the computational single crystal elastic constants, all the Al-Ni intermetallic compounds considered here are mechanically stable. The polycrystalline elastic modulus and Poisson's ratio have been deduced by using Voigt, Reuss, and Hill (VRH) approximations, and the calculated ratio of shear modulus to bulk modulus indicated that AlNi, Al{sub 3}Ni, AlNi{sub 3} and Al{sub 3}Ni{sub 5} compounds are ductile materials, but Al{sub 4}Ni{sub 3} and Al{sub 3}Ni{sub 2} are brittle materials. With increasing Ni concentration, the bulk modulus of Al-Ni intermetallic compounds increases in a linear manner. The electronic energy band structures confirm that all Al-Ni intermetallic compounds are conductors. - Graphical abstract: Calculated bulk modulus compared to experimental and other theoretical values for the Al-Ni intermetallic compounds.

Shi Dongmin [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Wen Bin, E-mail: wenbin@dlut.edu.c [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China); Melnik, Roderick [M2NeT Lab, Wilfrid Laurier University, Waterloo, 75 University Ave. West, Ontario, N2L 3C5 (Canada); Yao Shan; Li Tingju [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116023 (China)

2009-10-15

361

Thermodynamics of Al-substitution in Fe-oxyhydroxides  

NASA Astrophysics Data System (ADS)

Ab initio simulation results are presented for dilute Al-substitution in the common Fe-(oxyhydr)oxide materials hematite, goethite, lepidocrocite and ferrihydrite. Experimental evidence from the literature suggests that Al-substitution in these materials may influence particle stability and phase transformation behavior, typically stabilizing the oxyhydroxide phases relative to the oxide, hematite. We find that all the alloyed phases studied are unstable with respect to phase separation into their unalloyed Fe/Al-(oxyhydr)oxide end members. Among the phases studied, ferrihydrite is predicted to allow Al-substitution with the lowest energy cost, while hematite appears to have the strongest tendency for phase separation. Considering the effect on thermodynamic stability relative to the stable Fe-oxide hematite, the three Fe-oxyhydroxide materials (goethite, lepidocrocite, ferrihydrite) are shown to be stabilized relative to doped Al-hematite as Al content is increased. Interactions between Al dopant atoms on neighboring Fe sites are simulated and are shown to have minimal influence on Fe-Al alloying thermodynamics in each of the materials simulated within the range of Al-dopant concentrations calculated. Simulations of Al-substitutions at the goethite (1 0 1) surface indicate that surface segregation of Al dopants is energetically favored for low Al concentrations, however this tendency diminishes when Al dopants form a full monolayer at the mineral surface.

Pinney, Nathan; Morgan, Dane

2013-11-01

362

Tribological Properties of Ti(Al,O)/Al2O3 Composite Coating by Thermal Spraying  

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 air fuel (HVAF) thermally sprayed wear resistant Ti(Al,O)/Al2O3 coating on tool steel (H13) which is used for making dies for aluminium high pressure die casting and dummy blocks aluminium extrusion. A feedstock of Ti(Al,O)/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 air-fuel (HVAF) 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 wear resistance of the coating was investigated by a tribometer using a spherical ended alumina pin as a counter body under dry and lubricating conditions. The results showed that composite coating has lower wear rate at high temperature than at room temperature without using lubricant. 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, Asma; Gabbitas, Brian; Cao, Peng; Zhang, Deliang

363

THE THERMAL EXPANSION OF THE DIRECTIONALLY SOLIDIFIED Al-CuAl{sub 2} EUTECTIC  

SciTech Connect

Alloys of Al- CuAl{sub 2} eutectic composition were prepared from 99.999% pure materials and directionally solidified in a temperature gradient of about 45°C/cm at different growth rates R. The {lambda}{sup 2}R = constant relation was verified and lamellar spacings of 7.5, 3.5, 2.6, 1.8 and 1.4 ~m were obtained. Dilatometer specimens were machined with axes aligned in the principal lamellae coordinate directions. Thermal expansion was measured by standard dilatometry (Cu standard) using a set point program cycling between room temperature and 500°C . Thermal expansion of the directionally solidified Al-CuAl{sub 2} eutectic is greatest in the growth direction (in the plane of the lamellae), least in the transverse direction (orthogonal to the growth direction in the plane of the lamellae) and intermediate in the vertical direction (normal to the lamellae) . The most significant finding of the study is that the thermal expansion increases with decreasing lamellar spacing between limits defined approximately by the thermal expansion of the CuAl{sub 2} phase alone and the predicted thermal expansion of an isotropic elastic model of the composite.

Baker, Dennis F.; Bragg, Robert H.

1980-03-01

364

Quasiparticle diffusion in Al film and transmission with an Al/W interface  

NASA Astrophysics Data System (ADS)

The Cryogenic Dark Matter Search (CDMS) experiment uses both high-purity Si and Ge crystals to directly search for Weakly Interacting Massive Particles (WIMPs). These detectors simultaneously measure the ionization and phonon energy produced by particle interactions. This talk will focus on experiments performed with a separate set of test devices fabricated to study the fundamental physics of the CDMS phonon sensors. In our test experiments, an ^55Fe source was used to excite a NaCl reflector, producing 2.6 keV x-rays that hit our test devices after passing through a collimator. The devices under study consisted of a 250 ? m wide x 350 ? m long Al absorber film (300 nm thick) coupled to two 250 ? m x 250 ? m (40 nm thick) W transition edge sensors (TESs), one at each end of the Al film. The impinging x-rays break Cooper pairs in the Al film, producing quasiparticles that we detect as they propagate into the W TESs. We studied the diffusion of these quasiparticles, trapping in the Al film, and their transmission probability at the Al/W interfaces. Results from our precision experiments will be presented in this talk. These results are also being used to further optimize the design of SuperCDMS detectors for a proposed 100 kg scale dark matter search.

Yen, Jeffrey; Brink, Paul; Cabrera, Blas; Cherry, Matt; Pyle, Matt; Redl, Peter; Tomada, Astrid; Young, Betty

2013-03-01

365

Zirconium adsorption and incorporation on a reconstructed Al-T4 AlN(0001) surface  

NASA Astrophysics Data System (ADS)

We discuss the energetic stability and electronic structure of zirconium adsorption and incorporation on a 2×2 reconstructed AlN(0001) surface. We employ density-functional theory within the generalized-gradient approximation to study such effects. First-principles total energy calculations reveal that the most stable positions of a Zr adatom on the reconstructed 2×2-T4 AlN(0001) surface are at the S1 and Sp substitutional sites. In addition, calculating the relative surface energy of several configurations, we constructed a phase diagram showing the energetically most stable surfaces as a function of the aluminium chemical potential. Based on these results, we find that incorporation at Al-substitutional sites is energetically favorable compared to adsorption on the top layers. In particular, we find that Zr-S1 and Zr-Sp structures are stable over the entire chemical potential range. This effect can lead to the formation of a non-reactive interfacial ZrN(111) layer on the AlN(0001) surface, which can offer a good interfacial combination between AlN substrate and other metal contacts, i.e. zirconium.

López-Pérez, William; González-Hernández, Rafael; Rodríguez M, Jairo Arbey

2013-10-01

366

Hf dopants in ?'-Ni3Al alloy  

NASA Astrophysics Data System (ADS)

The Time Differential Perturbed Angular (TDPAC) measurements of nuclear quadrupole interactions (NQIs) at 181Ta ion probe in the polycrystalline intermetallic alloy ?'-Ni3Al doped with 0.2 at. % Hf were performed in the temperature range 78-1230 K, in order to determine the lattice location of Hf atoms in the ordered ?'-Ni3Al structure. The two NQIs obtained are discussed within the present L12 cubic structure and a tetragonal distortion of L12 to another two DO22 and L60 type structures. The first low frequency NQI at the site of the 181Ta ion-probe after substitution of aluminum for hafnium in DO22 at ambient temperature, is vQ1(300 K) = 39(1) MHz with ?1 = 0. The corresponding high frequency value on the second crystallographic site in L60, is vQ2(300 K) = 204(14) MHz with ?2 = 0.47(11). These two NQI's have different temperature behavior. The presence of both DO22 and L60 tetragonal distortions of the parent cubic L12 lattice, detected after adding 0.2 at. % Hf, are with modulations to the lattice constant (a) with a ratio (c/a), 2.04 and 0.87, respectively. Ab initio calculations of electronic and structural properties and hyperfine parameters at the 181Ta ion probe of the ?'-Ni3Al-0.2 at. % Hf alloy were performed using the full potential augmented plane wave plus local-orbital (APW+lo) method as implemented in the WIEN2k code. The accuracy of the calculations and comparison with the experimental results enabled us to identify the observed hyperfine interactions and to infer the EFG sign that cannot be measured in conventional TDPAC measurements.

Ivanovski, V. N.; Ceki?, B.; Umi?evi?, A.; Beloševi?-?avor, J.; Schumacher, G.; Koteski, V.; Barudzija, T.

2013-08-01

367

Rising crack-growth-resistance behavior of Al 2O 3 based composites toughened with Fe 3Al intermetallic  

Microsoft Academic Search

Al2O3 based composites containing 5–20vol.% of Fe3Al intermetallic second-phase particles were prepared by hot-pressing sintering. Significantly improved fracture toughness (8.1MPam1\\/2) and bend strength (860MPa) were achieved in Al2O3\\/20vol.% Fe3Al composite. The R-curve behavior for Al2O3\\/5–20vol.% Fe3Al composites was estimated by the indentation-strength method. The quantitative analysis of toughness increment indicates that the improvement was attributed to the crack bridging and

Jia Li; Hong-Yu Gong; Rui-Xia Shi; Yan-Sheng Yin

2007-01-01

368

Optimization of LiAl\\/NaAl-Cl sub 4\\/CuCl sub 2 thermal cells  

Microsoft Academic Search

The optimization of LiAl\\/NaAlCl4\\/CuCl2 single thermal cells is presented. Energy densities were obtained over the temperature range 175-275 degrees C and current density range 15-150 mA\\/square centimeters. The results were compared to similar data for LiAl\\/NaAlCl4\\/MoCl5 and LiAl\\/NaAlCl4\\/FeCl3 cells. Although the CuCl2 type cell had a lower voltage than the other types, its energy density was higher due to the

R. L. Vaughn

1979-01-01

369

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

370

The strengthening effect of Al{sub 3}Ti in high temperature deformation of Al-Al{sub 3}Ti composites  

SciTech Connect

A series of Al-Al{sub 3}Ti composites with systematic variation of Al{sub 3}Ti content were prepared by mechanical alloying. Microstructural observations have indicated that among these composites, the only distinct variable is the Al{sub 3}Ti content, while the other microstructural variables are essentially the same. The high temperature (623--773 K) deformation behavior of these composites was found to be similar to that of dispersion-hardened aluminum. By considering the presence of a threshold stress, the plastic flow in these composites can be described by lattice-diffusion controlled dislocation creep in the aluminum matrix with a constant structure. The presence of Al{sub 3}Ti particles can increase the creep strength of these alloys significantly. By considering the load-sharing effect of Al{sub 3}Ti, an analysis based on continuum mechanics approach has been conducted, which can successfully account for the creep rate of these Al-Al{sub 3}Ti composites. The threshold stress for creep in these composites was found to increase with increasing Al{sub 3}Ti content, which could be attributed to the load-shearing effect of Al{sub 3}Ti particles.

Wang, S.H.; Kao, P.W. [National Sun Yat-Sen Univ., Kaohsiung (Taiwan, Province of China). Inst. of Materials Science and Engineering

1998-05-01

371

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

372

Cavitation erosion of NiAl  

Microsoft Academic Search

Vibratory cavitation erosion tests were carried out on as-cast NiAl intermetallic compounds containing 46.5 to 62.1 at pct\\u000a Ni. The erosion rate decreased with increasing nickel content by over two orders of magnitude, from a high of 16.4 to 0.11\\u000a mgh?1. These low erosion rates exhibited by the nickel-rich alloys containing 58 and 62.1 at. pct Ni, the interruptions in

A. Akhtar; R. Salvi; V. K. Sikka

1999-01-01

373

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

374

Electron-impact ionization of Al2+  

NASA Astrophysics Data System (ADS)

We report on a nonperturbative R-matrix with PseudoStates (RMPS) calculation for the electron-impact ionization cross section of the ground state of Al2+. We include both the direct ionization of the 3s and 2p subshells and the indirect ionization from the 2p subshell. This calculation, thus, includes extra decay channels for the indirect-ionization process not included in previous RMPS calculations. This lowers the total-ionization cross section, resulting in closer agreement with the most recent experimental measurements. This calculation also shows better agreement with the position and height of the resonant-excitation double autoionization features seen in the experiment.

Wu, Di; Loch, S. D.; Pindzola, M. S.; Ballance, C. P.

2012-01-01

375

Experimental Phase Diagram of the Al-Er-Zr Ternary System  

Microsoft Academic Search

The phase diagram of the Al-Er-Zr ternary system at 773 K has been experimentally investigated by means of x-ray powder diffraction\\u000a (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM) with energy dispersive analysis (EDX). The\\u000a existence of 13 binary compounds, i.e. Al3Zr, Al2Zr, Al3Zr2, AlZr, Al3Zr4, Al2Zr3, AlZr2, AlZr3, Al3Er, Al2Er, AlEr, Al2Er3 and AlEr2 was confirmed. It is

Jing Hu; Yongzhong Zhan; Mingjun Pang; Chunliu Li; Wenchao Yang; Yong Du

376

78 FR 21428 - Royce Focus Trust, Inc., et al.;  

Federal Register 2010, 2011, 2012, 2013

...30447; File No. 812-14034] Royce Focus Trust, Inc., et al.; Notice of Application April 4, 2013. AGENCY: Securities...1\\ Royce Global Trust, Inc., et al., Investment Company Act Release Nos. 22665 (May 16,...

2013-04-10

377

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), DOT. ACTION...that establishes Class E airspace at Jackson Muni, Jackson, AL. DATES: Effective Date: 0901 UTC, April 21, 2010. FOR...

2010-04-21

378

75 FR 4270 - Modification of Class E Airspace; Anniston, AL  

Federal Register 2010, 2011, 2012, 2013

...09-ASO-22] Modification of Class E Airspace; Anniston, AL AGENCY: Federal Aviation Administration (FAA), DOT. ACTION...Class E airspace at Anniston Metropolitan Airport, Anniston, AL. DATES: Effective Date: 0901 UTC, January 27, 2010....

2010-01-27

379

75 FR 13670 - Amendment of Class E Airspace; Gadsden, AL  

Federal Register 2010, 2011, 2012, 2013

...No. 09-ASO-28] Amendment of Class E Airspace; Gadsden, AL AGENCY: Federal Aviation Administration (FAA), DOT. ACTION...amends Class E airspace at Northeast Alabama Regional, Gadsden, AL. DATES: Effective Date: 0901 UTC, March 23, 2010. FOR...

2010-03-23

380

Fabrication of Al{sub 2}O{sub 3}-Al composites by reactive melt infiltration  

SciTech Connect

An interpenetrating phase composite (IPC) is a multiphase material in which each phase is topologically interconnected throughout the microstructure. This unique structure provides several mechanical and electrical property advantages to the IPC material against traditional composites with isolated phases. In the present study, near-net-shape Al{sub 2}O{sub 3}-Al composites containing a small amount of silicon metal were fabricated by infiltrating aluminum into Al{sub 2}O{sub 3} particle preforms with the aid of borosilicate glass. This process was conducted under oxygen atmosphere at ambient pressure (1 atm) using a conventional furnace. The growth rate and the mechanical properties of the composites were investigated by changing the processing factors.

Tai, W.P.; Watari, Takanori; Torikai, Toshio

1997-04-01

381

Al atomic Auger electron emission from low-keV-ion-bombarded Al surfaces  

SciTech Connect

Al atomic {ital LMM} Auger electron emission from clean and oxygen- or argon-covered Al surfaces has been studied for low-keV Ar{sup +}-ion bombardment along normal and off-normal incidence directions. We show that, for a clean Al surface, many transitions are suppressed by the surface-neutralization process and that the quenching of such a neutralization mechanism and the activation of a surface-ionization mechanism by oxygen chemisorption or argon physisorption can unveil these hidden peaks. Our results provide some insights into the peculiarities of ion-solid interactions and offer an interesting explanation to the observed large difference in the relative transition ratios in experiments with solid and gas targets.

Xu, F.; Mandarino, N.; Zoccali, P.; Bonanno, A. (Dipartimento di Fisica, Universita della Calabria, 87036 Arcavacata di Rende, Cosenza (Italy))

1992-09-01

382

Optimization of the separation and purification of Al 13  

Microsoft Academic Search

The optimum process for the separation and purification of Al13 was investigated in detail in this paper. The various influencing factors were discussed. The experimental results show that the concentration and basicity (B, OH\\/Al ratio) of polyaluminum chloride (PACl), Al\\/SO4 ratio, Ba\\/SO4 ratio and ultrasonic reaction have different roles in the separation and purification of Al13. Moderate concentration of PACl

Yi Xu; Dongsheng Wang; Hong Liu; Lu Yiqiang; Hongxiao Tang

2003-01-01

383

Aluminum and silicon diffusion in Fe-Cr-Al alloys  

Microsoft Academic Search

Foils of Fe-Cr-Al alloys containing about 20 wt% Cr, 5 wt% Al and additions of Si and reactive elements like Ce, La, Y, Hf, Zr or Ti are widely used as a substrate in metal-supported automotive catalytic converters. In the present paper the authors report on measurements of Al and Si diffusion in Fe-Cr-Al alloys. Due to a lack of

A. Heesemann; E. Schmidtke; F. Faupel; A. Kolb-Telieps; J. Kloewer

1999-01-01

384

ALS2\\/Alsin Knockout Mice and Motor Neuron Diseases  

Microsoft Academic Search

Autosomal recessive mutations in the ALS2 gene have been linked to juvenile-onset amyotrophic lateral sclerosis (ALS2), primary lateral sclerosis and juvenile-onset ascending hereditary spastic paraplegia. Except for two recently identified missense mutations, all other mutations in the ALS2 gene lead to a premature stop codon and likely abrogate all the potential functions of alsin, the protein encoded by the ALS2

Huaibin Cai; Hoon Shim; Chen Lai; Chengsong Xie; Xian Lin; Wan Jou Yang; Jayanth Chandran

2008-01-01

385

Scaleup of powder metallurgy processed Nb-Al multifilamentary wire  

Microsoft Academic Search

Power metallurgy processed Nb-Al superconducting wires were fabricated from billets up to 45 mm o.d. with nominal areal reduction ratios, R, up to 2 X 10⁵, Nb powder sizes from 40 to 300 ..mu..m from various sources, Al powder sizes from 9 to 75 ..mu..m, Al concentrations from 3 to 25 wt % Al and with a wide range of

C. Thieme; H. Zhang; J. Otubo; S. Pourrahimi; B. Schwartz; S. Foner

1983-01-01

386

Development of Nb tube processed Nb 3 Al multifilamentary superconductor  

Microsoft Academic Search

The Nb tube process has recently been developed at NRIM (Japan) for fabricating Nb3Al multifilamentary superconductors containing more than one million continuous ultrafine filaments of less than 0.1 µm diameter. The adjustment of hardness of Al cores relative to Nb matrix by alloying Al cores with additives of Mg, Ag(-Ge), Cu(-Ge), Zn, etc. improved remarkably the cold workability of Nb\\/Al

T. Takeuchi; T. Kuroda; K. Itoh; M. Kosuge; Y. Iijima; T. Kiyoshi; F. Matsumoto; K. Inoue

1992-01-01

387

U–Mo\\/Al–Si interaction: Influence of Si concentration  

Microsoft Academic Search

Within the framework of the development of low enriched nuclear fuels for research reactors, U–Mo\\/Al is the most promising option that has however to be optimised. Indeed at the U–Mo\\/Al interfaces between U–Mo particles and the Al matrix, an interaction layer grows under irradiation inducing an unacceptable fuel swelling.Adding silicon in limited content into the Al matrix has clearly improved

J. Allenou; H. Palancher; X. Iltis; M. Cornen; O. Tougait; R. Tucoulou; E. Welcomme; Ph. Martin; C. Valot; F. Charollais; M. C. Anselmet; P. Lemoine

2010-01-01

388

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

389

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

390

Thermodynamic analysis of AlGaN HVPE growth  

Microsoft Academic Search

A thermodynamic analysis of the hydride vapor phase epitaxy (HVPE) of AlGaN using AlCl3 and GaCl as group III precursors is described. For a range of values on the input ratio, temperature, and the partial pressure of hydrogen in the carrier gas, we calculated the equilibrium partial pressures and the driving force for AlN and GaN deposition in AlGaN. As

Akinori Koukitu; Jun Kikuchi; Yoshihiro Kangawa; Yoshinao Kumagai

2005-01-01

391

The activity of Ni\\/AlPO 4 , Ni\\/AlPO 4 ?Al 2 O 3 and Ni\\/AlPO 4 ?SiO 2 catalysts in the hydrogenation of e-cinnamaldehyde  

Microsoft Academic Search

Liquid-phase catalytic hydrogenatio of E-cinnamaldehyde was carried out by using new supported nickel catalysts (Ni\\/AlPO4, Ni\\/AlPO4?Al2O3 and Ni\\/AlPO4?SiO2) in methanol as solvent under low hydrogen pressure (4.1 bar) and 298 K. The kinetic orders are zero in H2 and aldehyde. The selectivity to the hydrogenaton of the C=C double bond is very high (>99%)

J. M. Campelo; A. Garcia; D. Luna; J. M. Marinas

1981-01-01

392

Solar-blind ultraviolet photodetectors based on superlattices of AlN\\/AlGa(In)N  

Microsoft Academic Search

We describe solar-blind photodetectors based on superlattices of AlN\\/AlGa(In)N. The superlattices have a period of 1.4 nm, determined by x-ray diffraction, and an effective band gap of 260 nm measured by optical reflectivity. Using simple mesa diodes, without surface passivation, we obtain low dark leakage currents of 0.2-0.3 pA, corresponding to the leakage current density of ~0.3 nA\\/cm2, and high

V. Kuryatkov; A. Chandolu; B. Borisov; G. Kipshidze; K. Zhu; S. Nikishin; H. Temkin; M. Holtz

2003-01-01

393

Analysis of Al25 energy levels observed in the Si28(p,?)Al25 reaction  

NASA Astrophysics Data System (ADS)

The level structure of Al25 has been studied at the ORNL Holifield Radioactive Ion Beam Facility by measuring the angular and energy distributions of ? particles from the Si28(p,?)Al25 reaction. Proton beams (~10nA) at laboratory energies of 40 and 42 MeV were generated by the 25 MV tandem accelerator and bombarded a natural silicon target (50?g/cm2). Seventeen levels were observed and spins for several were constrained through a distorted-wave Born approximation analysis of the angular distributions.

Pittman, S. T.; Bardayan, D. W.; Blackmon, J. C.; Kozub, R. L.; Smith, M. S.

2009-09-01

394

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

395

Fabrication of Al/AlOx/Al Josephson junctions and superconducting quantum circuits by shadow evaporation and a dynamic oxidation process  

NASA Astrophysics Data System (ADS)

Besides serving as promising candidates for realizing quantum computing, superconducting quantum circuits are one of a few macroscopic physical systems in which fundamental quantum phenomena can be directly demonstrated and tested, giving rise to a vast field of intensive research work both theoretically and experimentally. In this paper we report our work on the fabrication of superconducting quantum circuits, starting from its building blocks: Al/AlOx/Al Josephson junctions. By using electron beam lithography patterning and shadow evaporation, we have fabricated aluminum Josephson junctions with a controllable critical current density (jc) and wide range of junction sizes from 0.01 ?m2 up to 1 ?m2. We have carried out systematical studies on the oxidation process in fabricating Al/AlOx/Al Josephson junctions suitable for superconducting flux qubits. Furthermore, we have also fabricated superconducting quantum circuits such as superconducting flux qubits and charge-flux qubits.

Wu, Yu-Lin; Deng, Hui; Yu, Hai-Feng; Xue, Guang-Ming; Tian, Ye; Li, Jie; Chen, Ying-Fei; Zhao, Shi-Ping; Zheng, Dong-Ning

2013-06-01

396

Electric Quadrupole Moments of Neutron Rich Al Isotope  

SciTech Connect

The electric quadrupole moment Q for the ground state of neutron-rich 31,32Al has been measured using {beta}-NMR method applied to spin-polarized projectile fragments. The obtained quadrupole moments are smaller than those of 27,28Al, which suggests spherical shapes of 31,32Al.

Yoshimi, A.; Ueno, H.; Kameda, D.; Sugimoto, T. [Nishina Center for Accelerator-based Science, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Asahi, K.; Nagae, D.; Takemura, M.; Shimada, K.; Takase, K.; Uchida, M.; Arai, T.; Inoue, T. [Department of Physics, Tokyo Institute of Technology, Oh-okayama 2-12-1, Meguro, Tokyo 152-8551 (Japan); Murata, J.; Kawamura, H. [Department of Physics, Rikkyo University, 3-34-1, Nishi-Ikebukuro, Toshima, Tokyo 171-8501 (Japan)

2007-05-22

397

The Global Expansion of the Al Qaeda Franchise  

Microsoft Academic Search

This thesis examines how the international terrorist group known as Al Qaeda has expanded its operations globally since 9\\/11. Case studies of Al Qaeda’s operations in the Arabian Peninsula, the United Kingdom, and the United States illustrate how the organization has exploited diverse environmental conditions to achieve either a limited or fully integrated local presence. This thesis argues that Al

Benjamin S Forster

2011-01-01

398

MG diffusion in anorthite - Survival of the Al-26 chronometer  

NASA Astrophysics Data System (ADS)

The presence of excess Mg-26 (from the decay of short-lived Al-26) provides key constraints on the time interval between Al-26 production in the interstellar medium and the formation of early solar system objects. Insofar as Al-26/Al-27 was initially uniform throughout the solar system, the Al-26-Mg-26 system can serve as a chronometer for events in the early solar system. If Al-26/Al-27 was initially uniform throughout the solar system, the large range in (Al-26/Al-27)o indicates that CAI and chondrule formation spanned over 5 Ma. A potential complication with this interpretation, however, is postcrystallization redistribution of Mg such as might occur during thermal metamorphism on protoplanets. In this case the Al-26-Mg-26 systematics would give no time information. Excess Mg-26 can thus far only be resolved in phases with Al/Mg above about 10, such as plagioclase. No data for Mg diffusion in plagioclase exist, however, and previous estimates of Mg diffusivity have been based on data for Sr. Here we present the first measurements of Mg self diffusion in anorthite. We then use these data to calculate the conditions under which Mg will isotopically exchange with surrounding phases and thus establish bounds on the thermal conditions required to preserve or destroy the Al-26 chronometer in anorthite.

Latourrette, T.; Wasserburg, G. J.

1997-03-01

399

Thermally induced structural modification in the Al/Zr multilayers  

NASA Astrophysics Data System (ADS)

The effect of increasing temperature on the structural stability and interactions of two kinds of Al/Zr (Al(1%wtSi)/Zr and Al(Pure)/Zr) multilayer mirrors are investigated. All Al/Zr multilayers annealed from 200 °C to 500 °C were deposited on Si wafers by using direct-current magnetron sputtering technology. A detailed and consistent picture of the thermally induced changes in the microstructure is obtained using an array of complementary measurements including grazing incidence X-ray reflectometry, atomic force microscopy, X-ray diffraction and high-resolution transmission electron microscopy. The first significant structural changes of two systems are observed at 250 °C, characterized by asymmetrical interlayers appearing at interface. At 290 °C, the interface consisting of amorphous Al-Zr alloy is transformed to amorphous Al-Zr alloy and cubic ZrAl3 in both systems. At 298 °C for Al(1%wtSi)/Zr and 295 °C for Al(Pure)/Zr multilayers, the interfacial phases of Al-Zr alloy transform into polycrystalline mixtures of hcp-ZrAl2 and cubic-ZrAl3, which smooth the interface boundary and lower the surface roughness in the multilayers. Up to 500 °C, the multilayer structure still exists in both systems, and the differences between the asymmetrical interlayers are much larger in the multilayers. Finally, we discuss the transformation from symmetrical to asymmetrical in the annealing process for other multilayer systems.

Zhong, Qi; Zhang, Zhong; Ma, Shuang; Qi, Runze; Li, Jia; Wang, Zhanshan; Jonnard, Philippe; Le Guen, Karine; André, Jean-Michel

2013-08-01

400

Ayman Al-Zawahiri: The Ideologue of Modern Islamic Militancy.  

National Technical Information Service (NTIS)

Egyptian physician Ayman Al-Zawahiri is considered by many to be the brains behind Al-Qaeda organization. Understanding Al-Zawahiri is to understand the most violent form of Islamic radicalism, one where there is no negotiation and an uncompromising attit...

Y. H. Aboul-Enein

2004-01-01

401

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

402

Hammam Al Alil Regional Training Center. Mosul, Iraq.  

National Technical Information Service (NTIS)

On 8 July 2009, SIGIR performed an on-site assessment of the Hammam Al Alil Regional Training Center. The Hammam Al Alil Regional Training Center is located at Forward Operating Base Scorpion in Hammam Al Alil, Iraq. The project site is approximately 15 m...

A. Johnston K. O'Connor S. Sassaman Y. Rawal

2010-01-01

403

Anisotropic Etching of Al by a Directed Cl2 Flux.  

National Technical Information Service (NTIS)

A new Al etching technique is described that uses an ion beam from a Kaufaman ion source and a directed Cl2 flux. The ion beam is used primarily to remove the native oxide to allow the Cl2 to spontaneously react with the Al film forming volatile Al2Cl6. B...

N. N. Efremow M. W. Geis R. W. Mountain G. A. Lincoln J. N. Randall

1986-01-01

404

Oxidation Behavior of FeAl+Hf,Zr,B.  

National Technical Information Service (NTIS)

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 gr...

J. L. Smialek J. Doychak

1988-01-01

405

78 FR 36411 - Amendment of Class E Airspace; Tuskegee, AL  

Federal Register 2010, 2011, 2012, 2013

...Amendment of Class E Airspace; Tuskegee, AL AGENCY: Federal Aviation Administration...action amends Class E Airspace at Tuskegee, AL, as the Tuskegee VOR/DME has been decommissioned...Moton Field Municipal Airport, Tuskegee, AL (78 FR 18928). Interested parties...

2013-06-18

406

76 FR 67054 - Amendment of Class E Airspace; Fayette, AL  

Federal Register 2010, 2011, 2012, 2013

...Amendment of Class E Airspace; Fayette, AL AGENCY: Federal Aviation Administration...action amends Class E Airspace at Fayette, AL, as the Fayette Non-Directional Beacon...rulemaking to amend Class E airspace at Fayette, AL (76 FR 44285) Docket No....

2011-10-31

407

77 FR 45238 - Amendment of Class E Airspace; Montgomery, AL  

Federal Register 2010, 2011, 2012, 2013

...Amendment of Class E Airspace; Montgomery, AL AGENCY: Federal Aviation Administration...amends Class E Airspace in the Montgomery, AL area, by recognizing the name change of...amends Class E airspace for the Montgomery, AL, area at the request of FAAs...

2012-07-31

408

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

409

Synthesis of Ti3Al and TiAl based surface alloys by pulsed electron-beam melting of Al(film)/Ti(substrate) system  

NASA Astrophysics Data System (ADS)

Phase formation and surface hardening in the 100-nm-thick Al(film)/Ti(substrate) system under conditions of pulsed electron-beam melting (˜15 keV, ˜3 ?s, 3-4 J/cm2) have been studied depending on the number of film deposition-melting cycles. Using this method, submicrocrystalline and nanocrystalline surface alloys with thicknesses ?3 ?m based on Ti3Al and TiAl intermetallics have been obtained on the titanium substrate.

Rotshtein, V. P.; Ivanov, Yu. F.; Kolubaeva, Yu. A.; Mei, X.; Markov, A. B.; Naiden, E. P.; Ozur, G. E.; Oskomov, K. V.; Popov, S. A.; Pryadko, E. L.; Teresov, A. D.; Shulov, V. A.

2011-03-01

410

The dependence of the ?-AlFeSi to ?-Al(FeMn)Si transformation kinetics in Al–Mg–Si alloys on the alloying elements  

Microsoft Academic Search

An homogenisation process is applied to as cast billets Al–Mg–Si alloys in order to improve the extrudability. During this homogenisation, plate-like ?-AlFeSi phase transforms to a more rounded ?-Al(FeMn)Si phase which are more favourable for the extrusion process. In this paper, the influence of the alloying elements on the rate of the intermetallic ?-to-? transformation is studied. A Finite Element

N. C. W. Kuijpers; F. J. Vermolen; C. Vuik; P. T. G. Koenis; K. E. Nilsen; S. van der Zwaag

2005-01-01

411

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

412

Site preferences of indium impurity atoms in intermetallics having Al3Ti or Al3Zr crystal structures  

NASA Astrophysics Data System (ADS)

Site-fractions of indium impurity probe atoms occupying up to three inequivalent Al-sites in Al3Ti, Al3V and Al3Zr phases were measured using perturbed angular correlation of gamma rays (PAC). Sites were identified via characteristic nuclear quadrupole interactions. Ratios of site-fractions were measured in thermal equilibrium in the range 600 to 1,210 K. Arrhenius plots of the ratios were fitted with thermally activated expressions, yielding differences in vibrational entropies and siteenthalpies. Enthalpy differences were greatest for Al3Zr, ˜0.22 eV, and smaller for Al3Ti and Al3V, which is correlated with the excess volume of the transition-metal atom over the Al-atom, Vibrational entropy differences were small, in the range 0 to -0.25 kB.

Bevington, John P.; Sellm, Farida; Collins, Gary S.

413

Site preferences of indium impurity atoms in intermetallics having Al3Ti or Al3Zr crystal structures  

NASA Astrophysics Data System (ADS)

Site-fractions of indium impurity probe atoms occupying up to three inequivalent Al-sites in Al3Ti, Al3V and Al3Zr phases were measured using perturbed angular correlation of gamma rays (PAC). Sites were identified via characteristic nuclear quadrupole interactions. Ratios of site-fractions were measured in thermal equilibrium in the range 600 to 1,210 K. Arrhenius plots of the ratios were fitted with thermally activated expressions, yielding differences in vibrational entropies and site-enthalpies. Enthalpy differences were greatest for Al3Zr, ~0.22 eV, and smaller for Al3Ti and Al3V, which is correlated with the excess volume of the transition-metal atom over the Al-atom. Vibrational entropy differences were small, in the range 0 to -0.25 kB.

Bevington, John P.; Selim, Farida; Collins, Gary S.

2007-06-01

414

Microstructure Analysis of AlGaN on AlN Underlying Layers with Different Threading Dislocation Densities  

NASA Astrophysics Data System (ADS)

Using the epitaxial lateral growth technique, we compared the crystallinity and relaxation ratio of 3-?m- and 200-nm-thick Al0.5Ga0.5N on an AlN template and AlN grown by epitaxial lateral overgrowth (ELO-AlN), both of which were grown on a sapphire substrate. Although the relaxation ratios of 3-?m-thick Al0.5Ga0.5N were almost the same, the misfit dislocation density at the interface and the density of threading dislocations reaching the surface of Al0.5Ga0.5N were significantly different. Also, the increase in the density of newly generated misfit dislocations was found to be highly dependent on the quality of the AlN underlying layer. We also discuss the difference in the initial growth mode of each Al0.5Ga0.5N sample.

Ide, Kimiyasu; Matsubara, Yuko; Iwaya, Motoaki; Kamiyama, Satoshi; Takeuchi, Tetsuya; Akasaki, Isamu; Amano, Hiroshi

2013-08-01

415

Thermodynamic and physical properties of FeAl and Fe3Al: an atomistic study by EAM simulation  

NASA Astrophysics Data System (ADS)

With this work we present a newly developed potential for the Fe-Al system, which is based on the analytical embedded atom method (EAM) with long range atomic interactions. The potential yields for the two most relevant phases B2-FeAl and D03-Fe3Al lattice constants, elastic constants, as well as bulk and point defect formation enthalpies, which are in good agreement with experimental and other theoretical data. In addition, the phonon dispersions for B2-FeAl and D03-Fe3Al show a good agreement with available experiments. The calculated lattice constants and formation enthalpy for disordered Fe-Al alloys are in good agreement with experimental data or other theoretical calculations. This indicates that the present EAM potentials of Fe-Al system is suitable for atomistic simulations of structural and kinetic properties for the Fe-Al system.

Ouyang, Yifang; Tong, Xiaofeng; Li, Chang; Chen, Hongmei; Tao, Xiaoma; Hickel, Tilmann; Du, Yong

2012-12-01

416

Unifying cluster-based structure models of decagonal Al-Co-Ni, Al-Co-Cu and Al-Fe-Ni.  

PubMed

The geometrical building principles of Al-based decagonal quasicrystals and their approximants are discussed from a cluster-based approach. Our investigations cover 11 modifications with two- or four-layer periodicity in the systems Al-Co-Ni, Al-Co-Cu and Al-Fe-Ni. We identified a cluster that leads to a unifying view of all these phases. This unit cluster has ~20 Å diameter, four-layer periodicity along its tenfold axis and rod symmetry group p102m. The models obtained are in agreement with all the electron-density maps and electron-microscopy images available. PMID:21245537

Deloudi, Sofia; Fleischer, Frank; Steurer, Walter

2011-01-15

417

Adhesive wear behaviour of B 4C and SiC reinforced 4147 Al matrix composites (Al\\/B 4C–Al\\/SiC)  

Microsoft Academic Search

Adhesive wear characteristics of 4147Al\\/B4C, 10, 15 and 20wt.% B4C particle and Al\\/SiC metal matrix composites 20wt.% SiC contain produced by liquid metallurgy have been investigated under the dry sliding conditions and their wear behaviours are compared with 4147 Al\\/SiC-reinforced 20wt.% SiC. The results showed that the wear resistance of Al\\/B4C matrix increases considerably with increasing wt.% B4C particle content

R. Ipek

2005-01-01

418

Measurement of the ^26gAl(d,p)^27Al Reaction to Constrain the ^26gAl Destruction Reaction Rate  

NASA Astrophysics Data System (ADS)

Detailed observations of the 1809-keV ? ray from the beta decay of ^26Al within the galaxy has provided an insight into ongoing nucleosynthesis. Understanding the abundance of ^26Al requires knowledge of the production and destruction rates for ^26Al. For temperatures where the ground-state and metastable state of ^26Al are decoupled, the ^26Al(p,?)^27Si reaction, which is determined by states near the proton threshold in ^27Si, contributes to the destruction rate. Though the strengths of many of these resonances have been measured directly, there remain uncertainties for the lowest resonances, which are relevant for giant star temperatures. We have measured mirror states in ^27Al to inform the ^27Si structure, via the ^26Al(d,p)^27Al reaction in inverse kinematics at the HRIBF. A beam of ˜5 million ^26Al per second impinged on a ˜150 ?g/cm^2 CD2 target. Proton ejectiles were detected in the SIDAR and ORRUBA silicon detector arrays. Details of the experimental setup and results will be presented. This work was supported in part by the US Department of Energy Office of Science and the National Science Foundation.

Pain, Steven

2012-10-01

419

Reaction between amorphous Si and crystalline Al in Al/Si and Si/Al bilayers: microstructural and thermodynamic analysis of layer exchange  

NASA Astrophysics Data System (ADS)

Aluminium-induced crystallization of amorphous silicon (a-Si) in Al/Si and Si/Al bilayers was studied upon annealing at 250 °C by X-ray diffraction and Auger electron spectroscopy. The Al/a-Si bilayers and a-Si/Al bilayers were prepared by sputter deposition on single-crystal silicon wafers with a silicon-oxide film on top. During the isothermal annealing a layer-exchange process occurred in both types of bilayers. A continuous polycrystalline silicon (poly-Si) film was formed within, and thereby gradually replacing, the initial Al metal layer. The sublayer sequence in the original bilayer influenced the speed of the poly-Si formation and the layer-exchange process. After annealing, the Al fiber texture in the as-deposited bilayers had become stronger, the Al crystallites had grown laterally, and the macrostress in the Al layer had been released. The amorphous Si layer had crystallized into an aggregate of nanocrystals with {111} planes parallel to the surface, with a crystallite size of about 15 25 nm. An extensive analysis of the Gibbs energy change due to annealing showed that the layer exchange may be promoted by the release of elastic energy and grain growth for the Al phase.

He, D.; Wang, J. Y.; Mittemeijer, E. J.

2005-02-01

420

Low-Temperature Fabrication of Polycrystalline Si Thin Film Using Al-Induced Crystallization without Native Al Oxide at Amorphous Si/Al Interface  

NASA Astrophysics Data System (ADS)

Low-temperature fabrication of polycrystalline silicon (poly-Si) thin film has been performed by Al-induced crystallization (AIC), and the structural properties have been investigated. In our experiments, to prevent native oxidation of Al film, an amorphous silicon (a-Si)/Al bilayer was formed on the SiO2/Si substrate by electron beam evaporation without breaking the vacuum. The a-Si/Al/SiO2/Si structure was then heated at a low temperature of 400°C to induce AIC. It was confirmed that layer exchange of the a-Si/Al bilayer is induced even though there is no native oxidation of Al film, which was demonstrated by scanning transmission electron microscopy and energy dispersive X-ray analysis. The mechanism for layer exchange of the a-Si/Al bilayer has been discussed. Furthermore, it was verified by scanning electron microscopy and spectroscopic ellipsometry that the a-Si/Al thickness ratio of roughly 1:1 is suitable to achieve a flat surface morphology of poly-Si. In addition, it was found, by X-ray diffraction and orientation imaging microscopy, that the Si(111)-oriented grain becomes dominant with decreasing thickness of the a-Si/Al bilayer.

Sugimoto, Youhei; Takata, Naoki; Hirota, Takeshi; Ikeda, Ken-ichi; Yoshida, Fuyuki; Nakashima, Hideharu; Nakashima, Hiroshi

2005-07-01

421

The ^16O(^16O,^26Al) and ^14N(^16O,^26Al) Reaction Rates and the Production of ^26Al in the Early Solar System  

NASA Astrophysics Data System (ADS)

The COMPTEL observation of 4.4 and 6.1 MeV gamma rays from the direction of the Orion Nebula led Clayton and Jin(D.D. Clayton and L. Jin, Ap.J., 451 (1995) 681) to propose that the production of the extinct ^26Al observed in meteorites was via the ^12C(^16O,^26Al) and ^16O(^16O,^26Al) reactions in the protosolar cloud by oxygen-rich cosmic rays with energies up to 10 MeV/amu. Results from the ^12C(^16O,^26Al) measurements of Bateman(N.P.T. Bateman, et al., Ap.J. 472 (1996) L119) indicate that this reaction could not have produced significant amounts of ^26Al in the solar nebula, unless almost all of the solar system ^16O had entered the nebula as high energy cosmic rays. Following up on this result, we have measured the yield of the ^16O(^16O,^26Al) and ^16O(^14N,^26Al) reactions. We have bombarded BeO samples with 85, 110, 135 MeV, and 155 MeV ^16O ions, and with 115 MeV ^14N ions. The ^26Al yield is measured by counting the beta-delayed gamma rays. The results will be presented.

Yildiz, K. O.; Bateman, N. P. T.; Butt, Y. M.; Chen, A. A.; Parker, P. D.

1997-04-01

422

Tracer diffusion behavior of Ga as an Al-substituting element in Ti 3Al and TiAl intermetallic compounds  

Microsoft Academic Search

Tracer diffusion of 69Ga was measured in pure ?-Ti, ?2-Ti3Al (33 at% Al), and ?-TiAl (54 at% Al) over wide temperature intervals up to the upper limits of stability of the corresponding phases. The concentration profiles were determined by secondary ion mass spectroscopy (SIMS). The diffusion coefficients revealed a good Arrhenius behavior with the frequency factors D0=2.1+0.7?0.5×10?3;6.3+9.7?3.8×10?5;and4.4+1.9?1.3×10?5m2s?1 and the activation

Chr. Herzig; M. Friesel; D. Derdau; S. V. Divinski

1999-01-01

423

Preparation and thermal decomposition studies of l-tyrosine intercalated MgAl, NiAl and ZnAl layered double hydroxides  

Microsoft Academic Search

l-Tyrosine (represented as l-Tyr) intercalated MgAl, NiAl and ZnAl layered double hydroxides (LDHs) have been obtained by the method of coprecipitation. In situ FT-IR, in situ HT-XRD and TG-DTA measurements allow a detailed understanding of the thermal decomposition process for the three intercalated composites. In situ HT-XRD reveals that the layered structure of l-Tyr\\/MgAl-LDH collapses completely at 450°C with the

Min Wei; Xiangyu Xu; Jing He; Qi Yuan; Guoying Rao; David G. Evans; Min Pu; Lan Yang

2006-01-01

424

Properties of NiAl and Ni-Al-N thin films deposited by closed field unbalanced magnetron sputter ion plating using elemental Ni and Al targets.  

PubMed

Approximately 1 microm thick NiAl and Ni-Al-N thin films have been deposited from individual elemental Ni (99.5% pure) and Al (99.5% pure) targets onto glass and stainless steel 316 substrates using closed field unbalanced magnetron sputter ion platting (CFUBMSIP) process. The films have been characterized using stylus profilometry, energy dispersive spectroscopy (EDAX), X-ray diffractometry (XRD) and atomic force microscopy (AFM). The X-ray diffraction patterns of both types of thin films produced confirmed the formation of beta-NiAl phase. The EDAX results revealed that all of the NiAl thin films produced exhibited the near equiatomic NiAl phase with the best results given by the one deposited using 300 Watts DC power for Ni and 400 Watts DC power for Al targets respectively. However, the Ni-Al-N thin films showed a Ni-rich NiAl phase. AFM results of both types of films produced carried out on glass samples exhibited that the coatings have quite a smooth surface with surface roughness in nanometres range. PMID:19916405

Baig, M N; Ahmed, W; Khalid, F A; Said, R M; McLaughlin, J

2009-07-01

425

Oxidation of RuAl and NiAl Thin Films: Evolution of Surface Morphology and Electrical Resistance  

Microsoft Academic Search

RuAl and NiAl thin films on SiO2\\/Si were oxi- dized, and the results were compared to those from aluminum, ruthenium, and nickel films. Both aluminides are more oxida- tion resistant than nickel, aluminum, and ruthenium, and they form an outer layer of alumina after oxidation to 850 ? C. The depth profiles differ for NiAl and RuAl, with alternating layers

Jane A. Howell; Christopher L. Muhlstein; B. Z. Liu; Q. Zhang; Suzanne E. Mohney

2011-01-01

426

Ternary site preference energies, size misfits and solid solution hardening in NiAl and FeAl  

Microsoft Academic Search

The electronic structure of NiAl and FeAl doped with Ti, V, Cr, Mn, Fe, Co, Y, La and Zr additions in both sublattices has been investigated with the local density linear muffin-tin orbital (LMTO) method. The peculiarities of chemical bonding for both undoped and with some ternary additions in NiAl and FeAl were analyzed using the LMTO-Green function method. The

N. I. Medvedeva; Yu. N. Gornostyrev; D. L. Novikov; O. N. Mryasov; A. J. Freeman

1998-01-01

427

Mutations in UBQLN2 cause dominant X-linked juvenile and adult-onset ALS and ALS/dementia.  

PubMed

Amyotrophic lateral sclerosis (ALS) is a paralytic and usually fatal disorder caused by motor-neuron degeneration in the brain and spinal cord. Most cases of ALS are sporadic but about 5-10% are familial. Mutations in superoxide dismutase 1 (SOD1), TAR DNA-binding protein (TARDBP, also known as TDP43) and fused in sarcoma (FUS, also known as translocated in liposarcoma (TLS)) account for approximately 30% of classic familial ALS. Mutations in several other genes have also been reported as rare causes of ALS or ALS-like syndromes. The causes of the remaining cases of familial ALS and of the vast majority of sporadic ALS are unknown. Despite extensive studies of previously identified ALS-causing genes, the pathogenic mechanism underlying motor-neuron degeneration in ALS remains largely obscure. Dementia, usually of the frontotemporal lobar type, may occur in some ALS cases. It is unclear whether ALS and dementia share common aetiology and pathogenesis in ALS/dementia. Here we show that mutations in UBQLN2, which encodes the ubiquitin-like protein ubiquilin?2, cause dominantly inherited, chromosome-X-linked ALS and ALS/dementia. We describe novel ubiquilin?2 pathology in the spinal cords of ALS cases and in the brains of ALS/dementia cases with or without UBQLN2 mutations. Ubiquilin?2 is a member of the ubiquilin family, which regulates the degradation of ubiquitinated proteins. Functional analysis showed that mutations in UBQLN2 lead to an impairment of protein degradation. Therefore, our findings link abnormalities in ubiquilin?2 to defects in the protein degradation pathway, abnormal protein aggregation and neurodegeneration, indicating a common pathogenic mechanism that can be exploited for therapeutic intervention. PMID:21857683

Deng, Han-Xiang; Chen, Wenjie; Hong, Seong-Tshool; Boycott, Kym M; Gorrie, George H; Siddique, Nailah; Yang, Yi; Fecto, Faisal; Shi, Yong; Zhai, Hong; Jiang, Hujun; Hirano, Makito; Rampersaud, Evadnie; Jansen, Gerard H; Donkervoort, Sandra; Bigio, Eileen H; Brooks, Benjamin R; Ajroud, Kaouther; Sufit, Robert L; Haines, Jonathan L; Mugnaini, Enrico; Pericak-Vance, Margaret A; Siddique, Teepu

2011-08-21

428

Comparative study of forging parameters on microstructures and properties between Aluminum alloys Al6063 and Al7075  

Microsoft Academic Search

This research were designed and created hot forging moulds of Aluminum alloys to investigate the effect of heating influence on machine qualifications of Aluminum alloys and know the suitable conditions of hot forging. The experimental variable was forging temperature and analyzed the experiment results for determined the suitable condition in hot forging on two types Aluminum alloysAlSi1Mg:Al6063 and AlZn5.5MgCuAl7075. The

S. SOPHA; S. NANSAARNG

2007-01-01

429

Preparation of Al 2O 3 coatings by pyrolysis of Al-acetylacetonate in Ar-atmosphere  

Microsoft Academic Search

Al2O3 coatings were deposited by pyrolysis of Al-acetylacetonate (? Al-acac) in Ar-atmosphere on graphite substrates with different surface roughnesses and on TiC-coated cemented carbide substrates. Compact and uniform Al2O3 coatings were obtained at temperatures up to 900 °C on the cemented carbides as well as on the graphite substrates with high surface roughness. At temperatures above 900 °C branched ‘cauliflower-like’

M. Danzinger; R. Haubner; B. Lux

1996-01-01

430

Investigation of the Al-Rich Part of the Al-Zr-Hf Phase Diagram for Solid State  

Microsoft Academic Search

Using electrical resistivity measurements, optical microscopy and scanning electron microscopy (SEM) with energy dispersive\\u000a x-ray analysis (EDX), the Al-rich corner of the Al-Zr-Hf phase diagram was studied. In the investigation the combined solubility\\u000a of Zr and Hf in solid Al at 600, 500, and 400 °C was determined. Zr and Hf significantly decrease the solubility of each other\\u000a in solid Al

L. L. Rokhlin; N. R. Bochvar; J. Boselli; T. V. Dobatkina

2010-01-01

431

Martensitic transformation of the Ni[sub 2]Al phase in 63. 1 at. % NiAl  

SciTech Connect

Electron diffraction and high resolution electron microscopy of 63.1 at.% NiAl have shown that the metastable hexagonal Ni[sub 2]Al precipitate, coherent in the B2 matrix phase, transforms concurrently with the martensitic transformation of the B2 NiAl matrix to the L1[sub 0] phase. The Ni[sub 2]Al precipitate that is coherent with the L1[sub 0] phase in monoclinic.

Murthy, A.S.; Goo, E. (Univ. of Southern California, Los Angeles, CA (United States). Dept. of Materials Science and Engineering)

1993-07-01

432

Low-frequency noise in AlGaN\\/GaN HEMT structures with AlN thin film layer  

Microsoft Academic Search

Low-frequency noise in AlGaN\\/GaN high electron mobility transistor (HEMT) heterostructures with additional AlN thin barrier layer is investigated. Transmission line model structures with different lengths of the conducting channel formed by polarization effects at the heterointerface of undoped AlGaN\\/AlN\\/GaN layers are studied. The measured noise demonstrates an unusual broadening of the generation-recombination components of the spectra. To explain the noise

S. A. Vitusevich; O. A. Antoniuk; M. V. Petrychuk; S. V. Danylyuk; A. M. Kurakin; A. E. Belyaev; N. Klein

2006-01-01

433

Remark on Yu et al.'s Online\\/Offline Signature Scheme in CT-RSA 2008  

Microsoft Academic Search

In CT-RSA 2008, Yu et al. proposed a family of three efficient Online\\/Offline signature schemes, which are especially suitable for the devices with limited computing capabilities. In this paper, we propose a new security model of Online\\/Offline signature. We find that Yu et al.' basic scheme is insecure under our model. We repair Yu et al.'s loophole by proposing a

Xiao-long Ma; Zhi-wei Wang; Li-ze Gu; Yi-xian Yang

2009-01-01

434

Oxidation of Al doped Au clusters: A first principles study  

SciTech Connect

Using first principles method we report the oxidation of Al doped Au clusters. This work is divided into two parts: (i) the equilibrium structures and stability of Al doped Au{sub n-1} clusters (n=2-7,21) and (ii) the interaction of O{sub 2} with stable clusters. The calculations are performed using the plane wave pseudopotential approach under the density functional theory and generalized gradient approximation for the exchange and correlation functional. The optimized geometries of Au{sub n-1}Al clusters indicate that the substitution of Au by Al results an early onset of three-dimensional structures from tetramer onwards. This is different from the results of transition metal doped Au clusters, where the planar conformation of Au clusters retains up to heptamer. The stability of Au{sub n-1}Al clusters has been analyzed based on the binding energy, second difference in energy, and the energy gaps between the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels. Based on the energetics, the Au{sub 3}Al and Au{sub 5}Al clusters are found to have extraordinary stability. The oxidation mechanism of Al doped Au clusters have been studied by the interaction of O{sub 2} with Al, Au, AuAl, Au{sub 3}Al, and Au{sub 20}Al clusters. It is found that the oxidation of Au{sub n-1}Al clusters undergoes via dissociative mechanism, albeit significant charge transfer from Al to Au. Moreover, the O{sub 2} molecule prefers to attach at the Al site rather than at the Au site.

Rajesh, Chinagandham [RMC, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Majumder, Chiranjib [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2009-06-21

435

Investigation of locally favored structures in Al-La-Ni metallic glasses using ^27Al NMR Spectroscopy  

NASA Astrophysics Data System (ADS)

Al-TM-RE (TM= transition metal, RE = rare earth) bulk metallic glasses (BMGs) with high Al content have gained much research interest due to their high potential as structural and functional materials. The first recent fabrication of La85-xAlxNi15 (15 <= x <= 70) BMGs have inspired an NMR systematic study of their locally favored structures (LFSs). These BMGs are reported to show characteristics of high thermal stability, fragility, and considerable mechanical strength. ^27Al NMR spectroscopy and nutation experiments are performed to unveil the sensitive structural dependence on line width and quadrupolar frequency with Al composition. It is observed that maximum glass forming ability (GFA) for this system prefers a decrease of symmetry at Al sites. Minimal GFA corresponding to instances of high symmetry occur in Al-rich and Al-poor regimes. These results, in addition to previous work, suggest that Ni and La atoms have unique local chemical and topological environments at different Al compositions. The monotonic decrease of relatively small ^27Al Knight shifts with increasing Al concentration demonstrates the evolution of local electronic structure at Al sites. This study is valuable in correlating the unique role that TM and RE elements play in local compositional and geometrical order of high glass-forming Al-based BMGs.

Sandor, Magdalena; Xi, Xuekui; Wu, Yue

2008-10-01

436

Probing Galactic 26Al with Exotic Ion Beams  

NASA Astrophysics Data System (ADS)

The goal of understanding the production of galactic 26Al brings together progress in nuclear astrophysics from observations, theory, meteoritics, and laboratory experiments. In the case of experimental work, nuclear reactions involving unstable isotopes are being studied to elucidate the production of 26Al in stellar explosive nucleosynthesis. We discuss a direct measurement of the 26Al(p,?)27Si reaction with the DRAGON collaboration at TRIUMF, and a measurement of 25Al+p elastic scattering with the CRIB (CNS-U.Tokyo) collaboration, toward constraining the 25Al(p,?)26Si reaction.

Chen, Alan A.

2006-07-01

437

Investigation of magnetic properties in 57Fe/Al multilayers  

NASA Astrophysics Data System (ADS)

Fe/Al multilayer thin films prepared by ion beam sputtering, with an overall atomic concentration ratio of Fe/Al = 1:2 have been studied by x-ray diffraction spectroscopy (XRD), X-ray reflectivity (XRR) and D.C. Magnetization. These studies show the formation of Fe Al intermetallic layers. Two magnetic regions and transition temperatures of 473 and 533 K are evident from magnetization studies. Conversion Electron Mössbauer Spectroscopy (CEMS) shows formation of off-stoichiometric Fe3Al like phase and phases consisting of pure Fe and Fe-rich extended Fe Al solutions.

Jani, Snehal; Sebastian, Varkey; Lakshmi, N.; Reddy, V. R.; Venugopalan, K.; Gupta, Ajay

2008-07-01

438

MnAl and MnAlC permanent magnets produced by mechanical alloying  

SciTech Connect

The ferromagnetic {tau} phase in the MnAl system, first reported by Kono and Koch et al., has the potential to replace anisotropic ferrites as a permanent magnet material. The {tau} phase is metastable and is usually produced by a rapid quench of the high temperature {var_epsilon} phase followed by isothermal annealing at temperatures between 400 and 700 C. Prolonged annealing results in decomposition of the {tau} phase to the equilibrium {gamma} and {beta}-Mn phases. The addition of carbon to the alloy stabilizes the {tau} phase against decomposition and improves both the magnetic properties and ductility. Mechanical alloying has been used successfully to synthesize a number of rare earth permanent magnet alloys, including Nd{sub 2}Fe{sub 14}B and SmCo{sub 5}. This processing technique can be used to produce a nanocrystalline microstructure, with a grain size below 10 nm, similar to some rapidly quenched structures. This small grain size can have beneficial effects upon the magnetic properties. The mechanical alloying of manganese and aluminum with compositions near 34 wt% Mn has been previously reported, however, no work appears to have been carried out in the region of the {tau} phase near 70 wt% Mn. In this paper the authors report the results of a study of the structure and magnetic properties of MnAl and MnAlC prepared by mechanical alloying and heat treatment.

Crew, D.C.; McCormick, P.G.; Street, R. [Univ. of Western Australia, Nedlands (Australia). Research Centre for Advanced Mineral and Materials Processing

1995-02-01

439

NiAl powder alloys: II. Compacting of NiAl powders produced by various methods  

NASA Astrophysics Data System (ADS)

The technological properties of granulated NiAl powders produced by gas spraying of melts and NiAl powders produced by calcium hydride reduction (CHR) of mixtures of nickel and aluminum oxides are compared. The possibilities of production of compact workpieces from these powders using hydrostatic pressing, hot pressing, hot isostatic pressing, and hot extrusion are estimated. To improve compressibility, preliminary milling and/or mechanical activation of the powders are proposed. The strength properties of NiAl rods with a diameter of 20 mm extruded from a temperature of 1100°C and made from the granulated powders are slightly higher than those made from the CHR powders. At temperatures higher than 800°C the properties becomes similar. Transition point t d.b from the ductile to brittle state of samples made from powders sprayed in nitrogen and argon is 100-150°C higher than those made from the CHR powders. The difference in the mechanical properties is caused by the structural and chemical microheterogeneity of granules (microingots), which is inherited in the rods after hot deformation and annealing at 1200-1400°C and is (0.67-0.88) T m NiAl ( T m is the melting point, K).

Skachkov, O. A.; Povarova, K. B.; Drozdov, A. A.; Morozov, A. E.

2012-05-01

440

Wetting of Cu and Al by Sn-Zn and Zn-Al Eutectic Alloys  

NASA Astrophysics Data System (ADS)

Wetting properties of Sn-Zn and Zn-Al alloys on Cu and Al substrates were studied. Spreading tests were carried out for 3 min, in air and under protective atmosphere of nitrogen, with the use of fluxes. In the case of Zn-Al eutectic, spreading tests were carried out at 460, 480, 500, and 520 °C, and in the case of Sn-Zn eutectic at 250, 300, 350, 400, 450, and 500 °C, respectively. Solidified solder/substrate couples were cross-sectioned and subjected to microstructure examination. The spreading tests indicated that the wetting properties of eutectic Sn-Zn alloys, on copper pads do not depend on temperature (up to 400 °C), but in the lack of protective atmosphere, the solder does not wet the pads. Wettability studies of Zn-Al eutectic on aluminum and copper substrates have shown a negative effect of the protective nitrogen atmosphere on the wetting properties, especially for the copper pads. Furthermore, it was noted that with increasing temperature the solder wettability is improved. In addition, densities of liquid solders were studied by means of dilatometric technique.

Pstru?, Janusz; Fima, Przemys?aw; Gancarz, Tomasz

2012-05-01

441

Improvement of Tseng et al.'s authenticated encryption scheme with message linkages  

Microsoft Academic Search

An authenticated encryption scheme is a message transmission scheme which sends messages in a secure and authentic way. In large message transmission, traditional authenticated encryption scheme has the disadvantage that the communication and the computation costs are too high. Recently, Tseng et al. proposed an authenticated encryption scheme with message linkages to reduce the computation time and communication costs for

Zhang Zhang; Shunsuke Araki; Guozhen Xiao

2005-01-01

442

Aesthetic Leadership (AL): Development and Implementation of Aesthetic Leadership Scale (ALS) of the School Directors  

ERIC Educational Resources Information Center

|This study aims to develop a scale for measuring the aesthetic leadership (AL) characteristics of the school directors and to show that it can be applicable. The population of the study is composed of the teachers who are on duty in the elementary, secondary and high schools located in Izmit, Kocaeli. Sample of this descriptive study comprises…

Polat, Soner; Oztoprak-Kavak, Zehra

2011-01-01

443

Microstructure and mechanical behaviour of Al–Si–Mg alloys reinforced with Ti–Al intermetallics  

Microsoft Academic Search

MMCs of aluminium alloy matrix reinforced with Ti–Al intermetallics were prepared in the laboratory by following a powder metallurgy route and hot extrusion or forging were used as consolidation processes. Different studies were carried out in the composites developed.In order to evaluate possible reaction products and interphases between the matrix and reinforcement, isothermal heat treatments regarding time were carried out

M. D. Salvador; V. Amigó; N. Martinez; D. J. Busquets

2003-01-01

444

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

445

Computational study of tetrahedral Al-Si and octahedral Al-Mg ordering in phengite  

NASA Astrophysics Data System (ADS)

As part of a wider study of the nature and origins of cation order-disorder in micas, a variety of computational techniques have been used to investigate the nature of tetrahedral and octahedral ordering in phengite, K2[6](Al3Mg)[4](Si7Al)O20(OH)4. Values of the atomic exchange interaction parameters Jn used to model the energies of order-disorder were calculated. Both tetrahedral Al-Si and octahedral Al-Mg ordering were studied and hence three types of interaction parameter were necessary: for T-T, O-O and T-O interactions (where T denotes tetrahedral sites and O denotes octahedral sites). Values for the T-T and O-O interactions were taken from results on other systems, whilst we calculated new values for the T-O interactions. We have demonstrated that modelling the octahedral and tetrahedral sheets alone and independently produces different results from modelling a whole T-O-T layer, hence justifying the inclusion of the T-O interactions. Simulations of a whole T-O-T layer of phengite indicated the presence of short-range order, but no long-range order was observed.

Palin, E. J.; Dove, M. T.; Redfern, S. A. T.; Saniz-Díaz, C. I.; Lee, W. T.

446

Constitutive Model Constants for Al7075-T651 and Al7075-T6  

NASA Astrophysics Data System (ADS)

Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these material. J-C strength model constants (A, B, n, C, and m) for the two alloys are determined from tension stress-strain data at room and high temperature to 250^oC. J-C strength model constants for Al7075-T651 are: A=527 MPa, B=676 MPa, n=0.71, C=0.017, and m=1.61 and for Al7075-T6: A = 546 MPa, B = 674 MPa, n = 0.72, C = 0.059, and m =1.56. J-C fracture model constants are determined form quasi-static and high strain rate/high temperature tests on notched and smooth tension specimens. J-C fracture model constants for the two alloys are: Al7075-T651; D1 = 0.110, D2 = 0.573, D3= -3.4446, D4 = 0.016, and D 5= 1.099 and Al7075-T6; D1= 0.451 D2= -0.952 D3= -.068, D4 =0.036, and D5 = 0.697.

Brar, Nachhatter; Joshi, Vasant; Harris, Bryan

2009-06-01

447

A theoretical study of the adsorption behavior of N2O on single-walled AlN and AlP nanotubes  

NASA Astrophysics Data System (ADS)

N2O molecule is both physically adsorbed on AlN and AlP nanotube.Sensitivity of AlN nanotubes are smaller and larger than those of AlP nanotubes, respectively.The results suggest that the binding energy of N2O on AlNNT is more noticeable in comparison to AlPNT.

Soltani, Alireza; Taghartapeh, Mohammad Ramezani; Tazikeh Lemeski, E.; Abroudi, Mehdi; Mighani, Hossein

2013-06-01

448

NMR study and hardness behavior of nanophase Al/Al-oxide consolidated composite  

NASA Astrophysics Data System (ADS)

Over the past few years, nanostructured materials (grain sizes 1-100 nm) have generated a lot of interest in the scientific community. This interest has mainly stemmed from the reported superior properties of these materials over conventional ones and their potential for commercial applications. A variety of techniques including SEM, TEM, PAS, etc. have been used to study nanophase materials. This work reports the study of a nanophase composite material using the non-destructive NMR spectroscopic technique. The composite studied is a nanophase Al/Al-Oxide system with the Al metal in the grains and the Al-Oxide in the grain boundaries. The production of such a nanoscale Al/Al-Oxide powder is described. Hardness, mass density and electrical conductivity measurements on the pellets formed by the consolidation of this powder at different consolidation pressures is reported. NMR studies of this composite material are reported at room temperature. The design and construction of a high temperature NMR probe is described. Limited high temperature NMR measurements are then described. Hardness measurements conducted on the samples indicate an increase in hardness with decrease in grain size in accordance with the Hall-Petch relationship. Interestingly, some of the samples were electrically conducting and some non-conducting. An increase in hardness with an insignificant change in mass density was observed in some samples. High temperature NMR results indicate the melting of the Al metal within the oxide at or around the melting point of aluminum (660sp°C). X-Ray measurements show no evidence of grain growth with increase in temperature. Both the X-Ray and NMR measurements show a substantial increase in the aluminum-oxide content of the samples after heating. NMR measurements performed on the samples before and after heating show a non-reversible behavior of the samples upon heating with respect to their signal intensity. Hardness tests performed on the samples after heating them indicate an increase in hardness by as much as a factor of five as compared to the hardness of the unheated samples. In conclusion, the experiments have successfully demonstrated the synthesis of a unique nanophase low density, high strength composite material capable of retaining its superior properties even above the melting point of aluminum.

Apte, Palash Prakash

449

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

2011-12-20

450

Kinetics of Al + H2O reaction: theoretical study.  

PubMed

Quantum chemical calculations were carried out to study the reaction of Al atom in the ground electronic state with H(2)O molecule. Examination of the potential energy surface revealed that the Al + H(2)O ? AlO + H(2) reaction must be treated as a complex process involving two steps: Al + H(2)O ? AlOH + H and AlOH + H ? AlO + H(2). Activation barriers for these elementary reaction channels were calculated at B3LYP/6-311+G(3df,2p), CBS-QB3, and G3 levels of theory, and appropriate rate constants were estimated by using a canonical variational theory. Theoretical analysis exhibited that the rate constant for the Al + H(2)O ? products reaction measured by McClean et al. must be associated with the Al + H(2)O ? AlOH + H reaction path only. The process of direct HAlOH formation was found to be negligible at a pressure smaller than 100 atm. PMID:21469719

Sharipov, Alexander; Titova, Nataliya; Starik, Alexander

2011-04-06

451

Is the Frontal Assessment Battery reliable in ALS patients?  

PubMed

The assessment of frontal functions in ALS patients is important because of the overlap with the behavioural variant of frontotemporal dementia (bvFTD). We investigated the applicability and reliability of the Frontal Assessment Battery (FAB) within a cohort of predominantly prevalent ALS patients. The FAB was administered to 85 ALS patients and eight ALS-bvFTD patients. Original scores and the percentage of items that could be performed were recorded. Item-adjusted scores of the FAB were calculated. The ALS Functional Rating Scale-Revised version (ALSFRS-R) was used to assess disease severity. Eighty-seven patients (94%) had ALS symptoms of more than one year. Twenty patients (21.5%) were not able to perform one or more FAB items. The original FAB score correlated with the ALSFRS-R score (r = 0.30; p < 0.01), while the item-adjusted FAB score did not. In contrast to the original FAB scores, the item-adjusted FAB score was lower in ALS-bvFTD patients (66.7, range 33.3-100) compared to ALS patients without bvFTD (94.4, range 38.9-100; p < 0.01). In summary, 20% of prevalent ALS patients could not complete the FAB, which limits its use in ALS and emphasizes the importance of disease specific instruments and adjusting for motor impairment in cognitive and behavioural examinations of ALS patients. PMID:22889176

Raaphorst, Joost; Beeldman, Emma; Jaeger, Bregje; Schmand, Ben; van den Berg, Leonard H; Weikamp, Janneke G; Schelhaas, H Jurgen; de Visser, Marianne; de Haan, Rob J

2012-08-13

452

Screening for cognition and behaviour changes in ALS.  

PubMed

This study presents the Edinburgh Cognitive and Behavioural ALS Screen (ECAS), developed for ALS patients with physical disability for use by health care professionals. The screen is designed to detect the specific profile of cognition and behaviour changes in ALS and to differentiate it from other disorders. Forty-eight ALS patients (none with evident dementia), 40 healthy controls and 20 carers were recruited. The ECAS, a 15-20-min screen, includes an ALS-Specific score (executive functions and social cognition; fluency; language); an ALS Non-specific score (memory; visuospatial functions); and a carer behaviour screen of five domains characteristic of frontotemporal dementia (FTD). Data from healthy controls produced abnormality cut-offs of 77/100 ALS-Specific score; 24/36 ALS Non-specific score; 105/136 ECAS Total. Twenty-nine percent of patients showed abnormal ALS-Specific scores, and 6% also showed abnormal ALS Non-specific scores. The most prevalent deficit occurred in language functions (35%) followed by executive functions and fluency (23% each). Forty percent of carers reported behaviour change in at least one domain, while 15% met criteria for possible FTD. In conclusion, the ECAS is an effective within-clinic assessment for ALS that determines the presence, severity and type of cognitive and/or behavioural changes, an essential first step to managing these symptoms. PMID:23781974

Abrahams, Sharon; Newton, Judith; Niven, Elaine; Foley, Jennifer; Bak, Thomas H

2013-06-19

453

Adsorption of carbon dioxide on Al/Fe oxyhydroxide.  

PubMed

The structure and reactivity of 0-70mol% Al/Fe iron oxyhydroxides (ferrihydrite in the absence and presence of Al) toward gaseous CO2 were investigated with X-ray photoelectron spectroscopy (XPS), atomic absorption (AA), scanning transmission electron microscopy with electron dispersive X-ray spectroscopy (STEM/EDS), X-ray diffraction (XRD), and attenuated total reflectance Fourier transform Infrared spectroscopy (ATR-FTIR) combined with density functional theory (DFT) calculations. Results showed that Al/Fe oxyhydroxide particles containing more than 20 mol% Al consisted at least in part of Fe-oxyhydroxide with incorporated Al and a discrete AlOOH phase. Results from ATR-FTIR experiments and DFT calculations suggested that the bicarbonate complex formed by passing CO2 over the particles was accommodated on at least three distinct binding sites. At the lowest Al concentrations bicarbonate was bound to individual sites with primarily Fe or Al character. At the highest concentrations of Al (>20 mol%) bicarbonate bound to discrete AlOOH phases became apparent. Results also suggested that the amount of CO2 adsorption for a given particle mass increased as the Al concentration was increased from 0 to 30%. This increase was likely due in large part to differences in the morphology of the particle aggregates that formed in the dry state, which would be expected to affect the amount of surface that was available to adsorb CO2. PMID:23561821

Pierre-Louis, Andro-Marc; Hausner, Douglas B; Bhandari, Narayan; Li, Wei; Kim, Jongsik; Kubicki, James D; Strongin, Daniel

2013-02-06

454

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

455

Removal of phosphate from water using six Al-, Fe-, and Al-Fe-modified bentonite adsorbents.  

PubMed

This study was part of a larger effort that involves evaluating alternatives to upgrading secondary treatment systems in the United Arab Emirates for the removal of nutrients. In this study, six modified bentonite (BNT) phosphate adsorbents were prepared using solutions that contained hydroxy-polycations of aluminum (Al-BNT), iron (Fe-BNT), and mixtures of aluminum and iron (Al-Fe-BNT). The adsorption kinetics and capacities of the six adsorbents were evaluated, and the adsorbents were used to remove phosphorus from synthetic phosphate solutions and from treated wastewater. The experimental adsorption kinetics results were well represented by the pseudo-second-order kinetic model, with R(2) values ranging from 0.99 to 1.00. Similarly, the experimental equilibrium adsorption results were well represented by the Freundlich and Langmuir isotherms, with R(2) values ranging from 0.98 to 1.00. The adsorption capacities of the adsorbents were dependent on the BNT preparation conditions; the types, quantities and combination of metals used; BNT particle size; and adsorption pH. The Langmuir maximum adsorption capacities of the six adsorbents ranged from 8.9-14.5 mg P/g-BNT. The results suggested that the BNT preparations containing Fe alone or in combination with Al achieved higher adsorption capacities than the preparations containing only Al. However, the Al-BNT preparations exhibited higher adsorption rates than the Fe-BNT preparation. Three of the six adsorbents were used to remove phosphate from secondarily treated wastewater samples, and the removal results were comparable to those obtained using synthetic phosphate solutions. The BNT adsorbents also exhibited adequate settling characteristics and significant regeneration potential. PMID:23043345

Shanableh, Abdallah M; Elsergany, Moetaz M

2013-01-01

456

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

457

Formation of Nb/sub 3/Al in powder processed Nb-Al superconductors  

SciTech Connect

In high magnetic fields, the critical current density is strongly dependent on the upper critical field, which is determined primarily by the stoichiometry of the Nb/sub 3/Al. The critical temperature (T/sub c/), like the upper critical field, is considered to be a measure of the ''intrinsic'' quality of the superconductor, indicating the stoichiometry, order, and strain. If the A15 phase is stoichiometric and well ordered, a high T/sub c/ (and high H/sub C/sub 2//) is expected, regardless of the volume fraction of superconductor. On the other hand, if sigma phase is present with the A15, the resultant composition gradient across the sigma-A15 interface(s) requires that some of the A15 be off-stoichiometric, and therefore that the T/sub c/ (and H/sub C/sub 2//) be low. Thus the extent of the A15 (Nb/sub 3/Al) reaction and the quality of the A15 formed are interdependent. This work focuses on the factors that control the extent of Nb/sub 3/Al formation in Nb/Al powder wires. The morphology and content of the reacted and unreacted wires are studied in optical, SEM, and TEM micrographs. Critical current density data and its dependence on processing are explained in terms of the unreacted microstructure and its effect on the extent of Nb/sub 3/Al formation. As a method of improving the critical current density, a new variation of the conventional powder process for wire manufacturing is developed and tested.

Johnson, P.E.

1987-05-01

458

Appearance of the bulk motif in Al clusters.  

PubMed

We have performed an unbiased search for the lowest-energy structures of medium-sized aluminum clusters Al(n) (n=19-26) using a genetic algorithm (GA) coupled with a tight-binding interatomic potential. Structural candidates obtained from our GA search were further optimized using density functional theory. It is found that the double icosahedron is not the most stable structure for Al(19) but serves as the core for Al(20) and Al(21). The lowest-energy structures of Al(n) are found to undergo a transition to an aluminum bulk motif above Al(23). In particular, the lowest-energy structure of Al(26) is almost a fragment of the bulk face-centered-cubic crystal except for the stacking fault at the bottom layer. Anion clusters were also studied. PMID:18624496

Sun, Jiao; Lu, Wen-Cai; Li, Ze-Sheng; Wang, C Z; Ho, K M

2008-07-01

459

Appearance of the Bulk Motif in Al Clusters  

SciTech Connect

We have performed an unbiased search for the lowest-energy structures of medium-sized aluminum clusters Al{sub n} (n=19-26) using a genetic algorithm (GA) coupled with a tight-binding interatomic potential. Structural candidates obtained from our GA search were further optimized using density functional theory. It is found that the double icosahedron is not the most stable structure for Al{sub 19} but serves as the core for Al{sub 20} and Al{sub 21}. The lowest-energy structures of Al{sub n} are found to undergo a transition to an aluminum bulk motif above Al{sub 23}. In particular, the lowest-energy structure of Al{sub 26} is almost a fragment of the bulk face-centered-cubic crystal except for the stacking fault at the bottom layer. Anion clusters were also studied.

Jiao Sun; Wen-Cai Lu; Ze-Sheng Li; C.Z. Wang; K.M. Ho

2008-07-07

460

Experimental characterization of ALS undulator radiation  

SciTech Connect

The radiation from the 5 cm period undulator at the Advanced Light Source (ALS) has been characterized using a transmission grating spectrometer. Spectral and angular distributions of radiation were measured for deflection parameter K values between 0.45 and 2.12 at low storage ring current (0.1--0.5 mA). From the calibration of the spectrometer, the absolute flux density of the undulator harmonics has been determined together with the spectral linewidth. The electron the beam emittance was determined by analyzing the angular distribution of the red-shifted fundamental. Comparison has been made with radiation calculations based upon the measured magnetic field data of the undulator. Including field errors, electron beam emittance and energy spread, good agreement is found between theoretically and experimentally determined harmonic widths and peak brightness.

Heimann, P.; Mossessian, D.; Warwick, A.; Gullikson, E.; Wang, C.; Marks, S.; Padmore, H.; Kincaid, B.

1994-07-15

461

Magnetic phase diagram of UCoAl  

NASA Astrophysics Data System (ADS)

We report precision c-axis magnetic measurements on a high-quality single crystal of the heavy fermion metamagnet UCoAl. The metamagnetic transition at H M changes from 1st order at low temperature to a crossover at high temperature. H M is nearly linearly increasing with increasing temperature up to a critical temperature T 0. The critical temperature T 0 is determined from both the field and the temperature dependences of magnetization to be ˜ 11 K. The field dependence of the Sommerfeld coefficient ? is estimated from M( T) by using a Maxwell relation. ?( H) shows a step-like decrease at H M . This behavior is consistent with the previous reports of specific heat and resistivity measurements at low temperatures.

Matsuda, Tatsuma D.; Tateiwa, Naoyuki; Yamamoto, Etsuji; Haga, Yoshinori; ?nuki, Yoshichika; Aoki, Dai; Flouquet, Jacques; Fisk, Zachary

2013-08-01

462

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

463

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

464

Spectral and intensity variations of Galactic 26Al emission  

NASA Astrophysics Data System (ADS)

Aims: Gamma-ray line emission from the radioactive decay of 26Al reflects nucleosynthesis in massive stars and supernovae. We use INTEGRAL 26Al measurements to characterize the distribution and characteristics of 26Al source regions throughout the Galaxy. Methods: The spectrometer SPI aboard INTEGRAL has accumulated over five years of data on 26Al gamma-ray emission from the Galactic plane. We analyzed these data using suitable instrumental-background models and adopted sky distribution models to produce high-resolution 26Al spectra of Galactic emission, spatially resolved along the Galaxy plane. Results: We detect the 26Al line from the inner Galaxy at 28? significance. The line appears narrow, and we constrain broadening in the source regions to <1.3 keV (2?). Different sky distribution models do not significantly affect those large-scale results. The 26Al intensity for the inner Galaxy is derived as (2.9± 0.2) × 10-4 ph cm-2 s^{-1 rad-1}, consistent with earlier results from COMPTEL and SPI data. This can be translated to an 26Al mass of 2.7 ± 0.7 M_? in the Galaxy as a whole. The 26Al intensity is also confirmed to be somewhat brighter in the 4th than in the 1st quadrant (ratio 1.3 ± 0.2). 26Al spectra separately derived for regions along the Galactic plane show clear line centroid shifts, attributed largely to the Galaxy's large-scale rotation. The 26Al line toward the direction of the Aquila region (20° < l < 40°) appears somewhat broadened. Latitudinal variations of 26Al emission towards the inner Galaxy are studied, finding a latitudinal scale height of 130+120-70 pc (1?) for 26Al in the inner Galaxy and a hint (3?) of peculiar 26Al emission towards the region l<0°, b>5°

Wang, W.; Lang, M. G.; Diehl, R.; Halloin, H.; Jean, P.; Knödlseder, J.; Kretschmer, K.; Martin, P.; Roques, J. P.; Strong, A. W.; Winkler, C.; Zhang, X. L.

2009-03-01

465

Passive film structure of supersaturated Al-Mo alloys  

SciTech Connect

This paper reports that reflection-extended x-ray absorption fine-structure spectroscopy has been used to probe the local atomic structure of the passive film of supersaturated Al-Mo alloys polarized in KCl. These alloys (with 7-11 atom percent Mo) exhibit resistance to localized attack with an increase in the pitting potential of {approximately} 600 mV relative to pure aluminum. Measurements show that the structure of the Al-Mo passive films resembles that of {alpha}-Al{sub 2}O{sub 3}/AlOOH, whereas an oxide film grown on pure Al in tartaric acid, which does not possess enhanced passivity, is more like {gamma}-Al{sub 2}O{sub 3}/AlOOH. Complementary x-ray photoelectron spectroscopy measurements indicate the Al-Mo passive film composition to be near that of AlOOH and the tartaric-acid film to be Al{sub 2}O{sub 3}. Because corundum ({Alpha}-Al{sub 2}O{sub 3}) and diaspore ({Alpha}-AlOOH), which contain only octahedrally coordinated Al atoms, are very stable and inert while {gamma}-Al{sub 2}O{sub 3}, which contains both octahedral and tetrahedral sites, is reactive, the change in structure of the passive film suggest that improved passivity may be correlated with a reduction in the density of tetrahedrally coordinated atoms. This structural change likely results from the incorporation of oxidized Mo into the passive film; only as this Mo is hydrated with a presumed change in local structure does the alloy pit.

Davis, G.D. (Martin Marietta Lab., Baltimore, MD (US)); Moshier, W.C. (Martin Marietta Space Systems, Denver, CO (US)); Long, G.G.; Black, D.R. (National Inst. for Standards and Technology, Gaithersburg, MD (US))

1991-11-01

466

Effects of TiC and Al 4C 3 addition on combustion synthesis of Ti 2AlC  

Microsoft Academic Search

Preparation of the ternary carbide Ti2AlC was conducted by combustion synthesis in the mode of self-propagating high-temperature synthesis (SHS) from the elemental powder compacts of Ti:Al:C=2:1:1, TiC-containing samples with TiC of 6.67–14.3mol%, and Al4C3-containing samples with Al4C3 of 1.96–10mol%. Effects of TiC and Al4C3 addition were studied on combustion characteristics and the degree of phase conversion. Due to the growth

C. L. Yeh; Y. G. Shen

2009-01-01

467

Synthesis of TiAl3Al2O3 Composite Particles by Chemical Reactions in Molten Salts  

Microsoft Academic Search

In this study, mechanically activated Al\\/TiO2 powders were heated in molten (NaCl +KCl) salts to obtain TiAl3-Al2O3 composite powders. The morphology and phase composition of the samples were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. It was shown that the milled powders reacted completely after 15 min at 800°C. Further investigations indicated that synthesized TiAl3-Al2O3 powders have

M. M. Verdian

2010-01-01

468

AlAs etch-stop layers for InGaAlAs\\/InP heterostructure devices and circuits  

Microsoft Academic Search

Wet chemical etching solutions have been developed that allow the selective etching of InP lattice matched InGaAlAs quaternary compounds using thin pseudomorphic AlAs layers as etch stops. The etch rate of In 0.53Ga0.47As in the InGaAlAs etchant is found to be over 70 times the etch rate of AlAs, while the etch rate of In0.52Al0.48As is over 35 times that

T. P. E. Broekaert; C. G. Fonstad

1990-01-01

469

Effects of thin MnAl buffer layer on structural and magnetic properties of MnAl films  

NASA Astrophysics Data System (ADS)

Thin Mn(2 nm)/Al(2 nm) bilayers serving as buffer layers have been prepared prior to the deposition of MnAl films. The ferromagnetic ?-phase forms in the buffer layers at an optimum substrate temperature. As a template it induces the growth of following MnAl film. Compared with the case of film without buffer layer, the growth of non-ferromagnetic phase is suppressed and the structural and magnetic properties of MnAl film are improved. Weak dipolar inter-grain coupling is revealed in the MnAl film, and the magnetic reversal process is dominated by magnetic moment rotation.

Zhang, Xu-Hui; Ma, Bin; Zhang, Zong-Zhi; Jin, Qing-Yuan

2010-10-01

470

Effect of Al 2 O 3 Content on Electrical Breakdown Properties of Al 2 O 3 \\/Cu Composite  

Microsoft Academic Search

Al2O3\\/Cu composites were prepared by external addition of Al2O3, and the effect of Al2O3 content on microstructure, density, hardness, electrical conductivity and vacuum electrical breakdown properties was studied.\\u000a The results show that with increasing Al2O3 addition, the density of Al2O3\\/Cu composite significantly decreases, the hardness sharply increases and then slowly decreases, but the electrical conductivity\\u000a invariably decreases. The vacuum breakdown

Xianhui Wang; Shuhua Liang; Ping Yang; Zikang Fan

2010-01-01

471

Characterization of AlGaN layer with high Al content grown by mixed-source HVPE  

Microsoft Academic Search

Using mixed-source hydride vapor-phase epitaxy (HVPE), an AlGaN layer with high Al content on GaN\\/Al2O3 substrate is obtained. The AlGaN layer grown by mixed-source HVPE is characterized by X-ray diffraction (XRD) measurements and cathodoluminescence (CL) spectra. In the mixed-source HVPE technique, the AlGaN material is compounded from the chemical reaction between NH3 and an aluminum-gallium chloride formed using HCl that

H. S. Ahn; K. H. Kim; M. Yang; J. Y. Yi; H. J. Lee; J. H. Chang; H. S. Kim; S. W. Kim; S. C. Lee; Y. Honda; M. Yamaguchi; N. Sawaki

2005-01-01

472

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

473

The electrochemical behavior of the Al{sub 3}Fe intermetallic compound and localized corrosion of impure 1100 Al  

SciTech Connect

Pitting of 1100 Al(Al-1.0(Fe,Cu,Si)) due to Al{sub 3}Fe constituent particles has been studied by examining a variety of intrinsic, extrinsic, and environmental factors that contribute to localized corrosion. Consistent with results from other studies, Al{sub 3}Fe is noble with respect to its microstructural surroundings and pitting is localized to the particle periphery. Polarization curves indicate that cathodic electron transfer reactions are supported on Al{sub 3}Fe at high rates, however, a anodic electron transfer reactions are not. Interparticle spacing appears to play a strong role in determining where pitting will occur, while Al{sub 3}Fe particle area plays a lesser role. Solution pH, applied potential, and exposure time each have measurable effects on the electrochemical behavior of Al{sub 3}Fe and the {alpha}-Al matrix phase which can impact either the galvanic potential of the Al{sub 3}Fe/{alpha}-Al couple, or charge transfer processes on Al{sub 3}Fe particles.

Buchheit, R.G.; Maestas, L.M.; Sorensen, N.R.

1993-11-01

474

Microstructures and mechanical behavior of NiAl-Mo and NiAl-MoTi two-phase alloys  

SciTech Connect

The phase relationship in the NiAl-Mo system is characterized by a eutectic equilibrium between binary NiAl and the terminal (Mo) solid solution, thereby offering the potential for development of ductile-phase-toughened composites. A study was conducted to evaluate the effect of varying volume fraction of the (Mo) phase on the microstructure, bend strength, and ambient temperature fracture behavior of selected NiAl-Mo two-phase alloys. Above room temperature, the NiAl-Mo alloys showed an increase in bend strength compared to monolithic NiAl, with reasonable strength retention up to [approximately]800 C. A further enhancement in toughness was realized through hot working. Fractography studies showed evidence for substantial decohesion between the (Mo) phase and the NiAl matrix, thereby suggesting the presence of a weak interface. This weak interface between the (Mo) phase and the NiAl matrix, in conjunction with modulus mismatch stresses, causes the crack to deflect from the (Mo) reinforcement and propagate preferentially along the (Mo)/NiAl interface. These attributes limit the potential for significant ductile-phase toughening in the NiAl-Mo system. An addition of 0.2 at. pct Ti resulted in a marked improvement in the room-temperature fracture toughness of NiAl-Mo. Fractography observations show some evidence for (Mo)/NiAl interface strengthening with the Ti addition.

Subramanian, P.R.; Mendiratta, M.G. (UES, Inc., Dayton, OH (United States). Materials Research Division); Miracle, D.B. (Air Force Wright Lab., Wright-Patterson AFB, OH (United States))

1994-12-01

475

Investigation of the role of Al/CoFe interface in proximity effect of Nb/Al/CoFe  

NASA Astrophysics Data System (ADS)

When a few nm-thick Al layer is inserted between Nb and ferromagnetic (F) layers such as CoFe, Ni, or CuNi, the superconducting critical temperature of the trilayers increase rapidly almost to a level of Nb/Al bilayers. In order to understand the role of Al/CoFe interface in the proximity effect of Nb/Al/CoFe, we have added Mg and Au scattering centers and found different behavior. The Mg scattering center did not change the critical temperature behavior of Nb/Al/CoFe, while the Au scattering centers reduced the critical temperature. The results point toward the importance of spin-orbit scattering. In addition, tunneling spectroscopy data on Nb/Al/F vs. on Nb/F will be presented in order to further characterize the role of Al/F interfaces.

Char, K.; Kwon, Junhyung; Lu, Wenjian

2008-03-01

476

Positron lifetime studies of decomposition in 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) alloys  

SciTech Connect

In the current paper, the decomposition behavior of the engineering alloys 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) is studied using positron lifetime measurements. Positrons probe open volume defects such as vacancies and dislocations. However, they may also be used to investigate coherent zones and incoherent precipitates. In order to understand the rather complicated precipitation sequences and the response of positrons to different type of precipitates occurring in 2024 and 7010 alloys, binary and ternary laboratory alloys were also investigated under the same experimental conditions as the engineering alloys. The interpretations of the results are based on experiences of the group from extensive positron studies of laboratory alloys such as Al-Zn, Al-Zn-Mg, Al-Cu, and further Al alloys (see also the review (4)). Their collected results are shown as lifetimes and curve-shape parameters S of the electron-positron momentum distribution curves characteristic for different precipitates in Al alloys.

Dlubek, G. [ITA Inst. fuer Innovative Technologien GmbH, Halle (Germany)]|[Martin-Luther-Univ. Halle-Wittenberg, Halle (Germany). Fachbereich Physik; Lademann, P.; Krause, H.; Krause, S.; Unger, R. [Martin-Luther-Univ. Halle-Wittenberg, Halle (Germany). Fachbereich Physik

1998-09-04

477

Characterisation of Phases and Lattice Parameter Measurement in the Al-Rich Corner of the Al-Si-Ti System  

NASA Astrophysics Data System (ADS)

Phases present in Al-12 wt%Si and Al-17.5 wt%Si alloys, with Ti content up to 4 wt%, prepared by rapid cooling, were characterised. The alloys were investigated by optical microscopy, X-ray fluorescence, X-ray diffractometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. The addition of Ti to Al-12 wt%Si alloy led to the precipitation of the intermetallic compound Al3Ti which dissolves up to 11.59 wt%Si, while its addition to Al-17.5 wt%Si alloy led to the precipitation of the ternary compound AlSi2Ti. Lattice parameters of the Al-rich phase and Si-rich phase were measured from X-ray diffraction data.

Daud, Abdul Razak; Saheb, Nouari

2002-04-01

478

X-ray high-pressure study of Ti2AlN and Ti2AlC  

NASA Astrophysics Data System (ADS)

The lattice parameters of Ti2AlN and Ti2AlC powders were measured as a function of pressure up to ?50 GPa, using a synchrotron radiation source and a diamond anvil cell. No phase transformations were observed. As for most related layered carbides and nitrides, such as Ti4AlN3 and Ti3SiC2, the compressibilities of Ti2AlN and Ti2AlC along the c-axes are larger than those along the a-axes. The bulk modulus of Ti2AlC at 186±2 GPa, is ?10% higher than that of Ti2AlN at 169±3 GPa.

Manoun, Bouchaib; Zhang, F. X.; Saxena, S. K.; El-Raghy, T.; Barsoum, M. W.

2006-09-01

479

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