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1

SISSIS Indirizzo Fisico-Matematico Laboratorio di Didattica dell'Analisi Matematica  

E-print Network

1 SISSIS ­ Indirizzo Fisico-Matematico Laboratorio di Didattica dell'Analisi Matematica Filippo Spagnolo 1. Introduzione al laboratorio.(1h) Una introduzione sul ruolo dell'analisi oggi, i problemi per poter poi confrontarla dopo il laboratorio. Criteri di valutazione Tesina Frequenza Esposizione

Spagnolo, Filippo

2

Analisi termica per la valutazione del danno negli acciai  

Microsoft Academic Search

RIASSUNTO. Sulla base di una metodologia consolidata, proposta in (26), per la definizione dell'intera curva di fatica di acciai mediante analisi termografica viene indicata una procedura per la valutazione del danno. Partendo dall'osservazione di base che ogni componente caricato dinamicamente, al di sopra del proprio limite di fatica, mostra un aumento di temperatura tanto più alto quanto più alto è

Antonino Risitano; Giacomo Risitano

2010-01-01

3

Analisi chimiche e microstrutturali dei materiali Analisi chimiche mediante ICP  

E-print Network

.penati@unitn.it. · Analisi di cristallizzazione in materiali amorfi Dipartimento di Fisica, Laboratorio Raggi X, prof. Dalba Dipartimento di Fisica, Laboratorio Chimica bioOrganica, prof. Guerriero. Tel. 0461 282013, e- mail: antonio maggiore accuratezza anche su quantità limitate di sostanza) Dipartimento di Fisica, Laboratorio Chimica

4

Analisi e caratterizzazioni nel settore biomedicale Analisi chimiche mediante ICP  

E-print Network

.penati@unitn.it. · Analisi di cristallizzazione in materiali amorfi Dipartimento di Fisica, Laboratorio Raggi X, prof. Dalba Dipartimento di Fisica, Laboratorio Chimica bioOrganica, prof. Guerriero. Tel. 0461 282013, e- mail: antonio maggiore accuratezza anche su quantità limitate di sostanza) Dipartimento di Fisica, Laboratorio Chimica

5

COMUNICATO STAMPA Analisi Applicata del Comportamento (ABA) ed Autismo  

E-print Network

COMUNICATO STAMPA Analisi Applicata del Comportamento (ABA) ed Autismo Data Scadenza: 10 giugno 2014 ANALISI APPLICATA DEL COMPORTAMENTO (ABA) ED AUTISMO L'Università di Salerno ha pubblicati i bandi trattamento dei bambini con autismo secondo i criteri del metodo ABA (Analisi Applicata del Comportamento). I

Costagliola, Gennaro

6

ANALISI SPERIMENTALE DELLE PRESTAZIONI OTTENIBILI CON TUBI DI LUCE E CONFRONTO CON SISTEMI TRADIZIONALI DI CAPTAZIONE DELLA LUCE NATURALE 1  

Microsoft Academic Search

Il presente articolo illustra i primi risultati di un'analisi di carattere sperimentale condotta presso il Laboratorio di Fisica Tecnica della Facoltà di Architettura di Pescara al fine di caratterizzare il comportamento di sistemi di captazione e trasporto della luce naturale, \\

C. Baroncini; B. Calcagni; F. Chella; P. Zazzini

7

IMPLEMENTACIÓN DE UNA FORMULACIÓN RAPIDA DE MULTIPOLOS APLICADOS AL MÉTODO DE LOS ELEMENTOS DE CONTORNO  

Microsoft Academic Search

Resumen. Se presenta en este trabajo una descripción completa del algoritmo de Multipolos Rápidos combinado con el Método de los Elementos de Contorno (FMBEM, en inglés) y su implementación para un problema de potencial estacionario. Se usa la alternativa de una formulación usando variable compleja. El algoritmo implementado es luego validado y calibrado para resolver problemas que consisten en el

Marco Dondero; Adrián P. Cisilino; Georgios Stavroulakis

8

Scatter Search aplicado aplicada al problema de la minimizacion del profile de matrices y grafos  

E-print Network

la estrategia Path Relinking como m´etodo base para la genera- ci´on de nuevas soluciones mediante los 70 pero en el estado del arte no se encuentra ning´un m´etodo eficiente para la resoluci´on del obtener en tiempo polin´omico. Por ejemplo, en [19] se proponen varios algoritmos que encuentran la soluci

Duarte, Abraham

9

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

10

COMPORTAMENTO A FATICA DI COMPONENTI MECCANICI SOGGETTI A SOLLECITAZIONI RANDOM: ANALISI CRITICA DEI METODI IN FREQUENZA  

Microsoft Academic Search

SOMMARIO Nell'ambito della progettazione meccanica, grazie alle enormi potenzialità degli odierni strumenti di calcolo per la modellazione FEM e multibody, è ormai realisticamente utilizzabile una procedura di analisi a fatica di componenti meccanici sollecitati in maniera random i cui diversi passi vengono risolti tutti completamente nel dominio della frequenza. La fase più debole di questa metodologia rimane la valutazione diretta

G. Lori; D. Pioli

11

Algoritmos Genéticos Aplicados a la Categorización Automática de Documentos  

Microsoft Academic Search

Resumen - La categorización automática de documentos ha estado recibiendo creciente atención debido al incremento en la cantidad de información disponible en forma electrónica y a la necesidad cada vez mayor de encontrar la información buscada en un tiempo mínimo. Si bien existen numerosos algoritmos para categorizar documentos, todos ellos evaluan un subconjunto pequeño del espacio de posibles soluciones. Este

E. Yolis; P. Britos; G. Perichisky; R. García-Martínez; Paseo Colón

12

Mineria de datos sobre grafos: un enfoque multiobjetivo aplicado a bioremediacion  

E-print Network

Miner´ia de datos sobre grafos: un enfoque multiobjetivo aplicado a bioremediaci´on J. Zaiat1 and R subdividirlo en varias submol´eculas inocuas. La miner´ia de datos resulta entonces una herramienta muy ´util para resolver este problema, sin embargo existen pocos trabajos sobre miner´ia de datos aplicada

Granada, Universidad de

13

PROCEDIMIENTO PARA EL DIAGNÓSTICO DE LA LOGÍSTICA INTERNA APLICADO EN UNA EMPRESA DE SERVICIOS EXTRAHOTELEROS  

Microsoft Academic Search

En este trabajo se presenta un procedimiento para realizar el diagnóstico de la logística interna, el cual fue aplicado en una empresa de servicios extrahoteleros. A partir de su aplicación se determinó un banco de problemas teniendo en cuenta las principales dificultades encontradas, así como un conjunto de acciones que le permitieron a la entidad mejorar los niveles de eficiencia

Damaris Valdés Ferrer

2012-01-01

14

Fattori che promuovono il processo di crescita post-traumatica: una meta-analisi  

Microsoft Academic Search

Riassunto La crescita post-traumatica indica la tendenza a riferire cambiamenti positivi a livello personale e so- ciale dopo aver vissuto un trauma. Recenti rassegne sull'argomento hanno ipotizzato che risorse per- sonali e sociali e specifiche strategie di coping possano favorire la crescita post-traumatica anche se le evidenze in letteratura sono contrastanti. La presente meta-analisi ha indagato il ruolo dell'ottimismo e

Gabriele Prati

2007-01-01

15

1.1 Analisis y Dise~no 1 1.1. Analisis y Dise~no  

E-print Network

tiroliros. Ha logrado fama mundial gracias al estricto control de la calidad y al minucioso proceso de para automatizar el proceso de control de calidad y categorizaci´on. Ya tienen bien definida la soluci determinar la calidad de la fruta. Los distintos atributos de cada pieza son medidos. Comparando estos

Castillo, Luis

16

Analisi Matematica 1 per Matematica Esercizi decima settimana  

E-print Network

metro al secondo. Ai piedi della scala c'`e un uomo eretto alto 2 m che si sposta con la scala. All'estremo superiore della scala `e attaccata una lampadina che si muove con la scala strisciando lungo la parete. Con

Marconi, Umberto

17

ALS Association  

MedlinePLUS

... help fight ALS. Read More » Walk to Defeat ALS® Season Starts Now is the time to put ... Therapy Month Read More » The Leader in Global ALS Research The ALS Association has committed $99 million ...

18

The Dirichlet Problem for the Total Variation Flow Dept. de An'alisis Matem'atico, Universitat de Valencia, 46100 Burjassot (Valencia), Spain  

E-print Network

'atico, Universitat de Valencia, 46100 Burjassot (Valencia), Spain C. Ballester Department of Tecnologia, University of Pompeu­Fabra, La Rambla 30­32, 08002 Barcelona, Spain V. Caselles Department of Tecnologia, University of Pompeu­Fabra, La Rambla 30­32, 08002 Barcelona, Spain J. M. Maz'on Dept. de An'alisis Matem

Caselles, Vicent

19

Análisis Comparativo de Algoritmos Genéticos Aplicados a Calendarización de Trabajos en un Grid Computacional  

Microsoft Academic Search

Resumen. Este artículo aborda la calendarización de trabajos paralelos en un Grid jerárquico con dos etapas. En esta configuración uno de los grandes retos es asignar las tareas de manera que permita un uso eficiente de los recursos, al mismo tiempo que satisface otros criterios. En general, los criterios de optimi- zación a menudo están en conflicto. Para resolver este

Victor Hugo Yaurima Basaldúa; Andrei Tchernykh; Moisés Torres Martínez

2013-01-01

20

ALS - resources  

MedlinePLUS

Resources - ALS ... The following organizations are good resources for information on amyotrophic lateral sclerosis : Muscular Dystrophy Association - http://mda.org/disease/amyotrophic-lateral-sclerosis National Amyotrophic Lateral Sclerosis (ALS) ...

21

Initial Symptoms of ALS  

MedlinePLUS

Home About ALS About Us Our Research In Your Community Advocate Help fight ALS Donate About ALS What is ALS? Facts You Should Know Who does ALS affect? Diagnosing ALS Symptoms Forms of ALS Genetic ...

22

Al Composites  

NASA Astrophysics Data System (ADS)

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

Chandanayaka, Tharaka; Azarmi, Fardad

2014-05-01

23

E' professore associato di Analisi Numerica presso Universita' di Roma "Tor Vergata" dal 2007. E' stato ricercatore di ruolo dal 2000 presso l'Universita' di Roma "La Sapienza. Ha conseguito il dottorato di Ricerca  

E-print Network

E' professore associato di Analisi Numerica presso Universita' di Roma "Tor Vergata" dal 2007. E' stato ricercatore di ruolo dal 2000 presso l'Universita' di Roma "La Sapienza. Ha conseguito il di Matematica Universita' di Roma "Tor Vergata" di un progetto Ricerca Finalizzata sicurezza sui

Bertaccini, Daniele

24

[AL amyloidosis].  

PubMed

AL amyloidosis belongs to the group of conformational diseases. It is the most common type of amyloidosis with an estimated 500 new cases per year in France. It is due to a small and usually indolent plasma cell clone which synthesizes an unstable, misfolded monoclonal immunoglobulin light chain that is prone to aggregate and form amyloid fibrils. Non-invasive biopsy such as abdominal fat aspiration or minor salivary gland biopsy should be performed to confirm the diagnosis and if negative, involved tissues have to be examined. Clinical presentation is very diverse, as AL amyloidosis can affect almost any organ or tissue in the body, other than the brain. The kidney is the most frequent organ involved, whereas heart disease characterized by restrictive cardiomyopathy is the most severe. Early diagnosis, before advanced cardiomyopathy, is essential for improving outcome. The association of alkylating agent and high-dose dexamethasone is effective in almost two-thirds of patients. Combinations of proteasome inhibitors, dexamethasone, and alkylating agents achieve high response rates. Close monitoring of clonal and organ response is mandatory to guide therapy changes and duration. New treatments designed to eliminate amyloid deposits are under development. PMID:25194219

Jaccard, A; Desport, E; Mohty, D; Bridoux, F

2015-02-01

25

Analisis del contenido curricular de los Documentos Normativos del Programa de Ciencias en el area de biologia para la escuela superior del sistema de educacion publica de Puerto Rico: 1993-2012  

NASA Astrophysics Data System (ADS)

Esta investigacion de naturaleza cualitativa se ocupo de realizar un analisis de contenido documental de los Documentos Normativos del Programa de Ciencias en el area de biologia de la escuela superior del sistema de educacion publica de Puerto Rico del periodo 1993-2012. Los documentos analizados fueron: Guia Curricular, 1995; Marco Curricular, 2003; Estandares de Excelencia, 1996, 2000 y Estandares de Contenido y Expectativas de Grado, 2007. Se indago si hubo cambios en significados en los Componentes Estructurales: Naturaleza de la ciencia, Paradigmas para la ensenanza de la ciencia, Funcion del curriculo formal, Mision de la ensenanza de la ciencia; Contenidos, destrezas y competencias, Estrategias de ensenanza y Evaluacion/Assessment del aprendizaje. El analisis sugiere que no hubo cambios sustanciales en los significados de los Componentes Estructurales. Los documentos estudiados muestran mayormente caracteristicas similares, aunque los documentos mas recientes eran mas descriptivos, explicativos y especificos.

Davila Montanez, Melissa

26

Analisis de Alteraciones EN la Imagen Debidas a Descolimacion de un Telescopio  

NASA Astrophysics Data System (ADS)

Podemos considerar, en términos generales, que los espejos de un telescopio tienen una calidad óptica intrínseca, entendiendo por ésta la que se ha obtenido como resultado, fundamentalmente, de la destreza del personal del Taller Optico, que considerará terminadas las superficies ópticas cuando éstas satisfagan los requisitos de diseño y las pruebas de evaluación pertinentes. Debemos esperar que, una vez instalados los espejos en el telescopio, no se altere esta calidad de la óptica por un funcionamiento inadecuado de partes mecánicas del mismo. En los últimos años, en la medida que los problemas de infraestructuratura de nuestros Observatorios se han ido resolviendo, se ha hecho más patente la necesidad de llevar a la instrumentación existente al máximo de su potencial y parte esencial de ésta la conforman los mismos te lescopios. Mejorar la calidad óptica de las imágenes obtenidas con ellos ha hecho que sea prioritario el realizar una investigación más sistemática de sus características. Este trabajo ha tenido como objetivo primordial el usar un programa de diseño óptico, en el caso particular del telescopio UNAM212, con el fin de calcular y obtener gráficamente los diagramas de manchas de imagenes en foco y extrafocales, tanto con la óptica perfectamente alineada como descolimándola (mediante pequenos giros y descentramientos de los espejos). De esta manera, se hizo una evaluación de los efectos que estas alteraciones simuladas producirían en las imágenes focales y extra focales para así poder compararlas con las que realmente se han observado. Asimismo, se ha buscado información bibliográfica, en particular sobre los efectos de giros y descentramientos en las imágenes extrafocales, en lo que se ref iere a la falta de concentricidad de los círculos que forman la "dona" y a la distribución de intensidad luminosa en la misma. De ésta, l futuro un proceso que, haciendo uso de los detectores bidimensionales, nos permita Ilevar a cabo una alineación más rigurosa de la óptica del telescopio y evaluar con precisión Si variaciones en el posicionado del misesperamos desarrollar en emo producen efectos de descolimación.

Cobos, F. J.; Galan, M. J.

1987-05-01

27

Schwartz et al., Tella et al., Foltin et al., Trippenbach et al., Regalado et al., Magnano et al., Levin et al., Hale et al., Cocaine day  

E-print Network

., Levin et al., Hale et al., Cocaine day 7 day dry-out period Session I: Baseline Session II: Fixed 8mg, and 32 mg\\70kg respectively with a 100kg cap. All cocaine self-administration sessions take place at the Yale Center for Clinical Investigations Hospital Research Unit. Detecting Signatures of Cocaine Using

Massachusetts at Amherst, University of

28

Primary AL Amyloidosis  

MedlinePLUS

... be administered in combination with other treatments. REVLIMID (lenalidomide) (CC-5013) is a immunomodulatory drug; a derivative ... AL amyloidosis. Findings from initial trials indicate that lenalidomide can be effective in treating AL amyloidosis. There ...

29

About ALS: FAQ  

MedlinePLUS

... disease deterioration in these mice. Clinical trials are of the utmost importance to investigate if the effects seen in the mouse model are seen in humans with ALS. Another question is whether this exciting result found in a model of familial ALS is applicable to sporadic ALS that ...

30

Al Dimer Dynamics on Al(111)  

NASA Astrophysics Data System (ADS)

Al dimer dynamics on Al(111) at equilibrium and under compression is studied using first-principles density-functional theory calculations. A smooth potential energy surface provides a long-range attraction between the dimer atoms and leads to a substantial temperature window in which dissociation is frozen and exotic dimer dynamics is observed. Surface relaxations play a prominent role in the uncovering of an unexpected ground state and a new diffusion path. A way of affecting growth by compression is illustrated. The possibility of a metal quantum rotor is addressed and further examined using effective-medium theory calculations.

Bogicevic, Alexander; Hyldgaard, Per; Wahnström, Göran; Lundqvist, Bengt I.

1998-07-01

31

Modelo de accesibilidad de conceptos matematicos aplicados en el curso de Astronomia Descriptiva para estudiantes con impedimentos visuales en la UPR  

NASA Astrophysics Data System (ADS)

Este estudio utiliza metodologia de investigacion cualitativa, con el proposito de describir, analizar y evaluar los procesos de diseno y desarrollo de un modelo de accesibilidad que consiste en estrategias de ensenanza de las matematicas para estudiantes con impedimentos visuales matriculados en el curso de Astronomia Descriptiva en la UPR. Se utilizaron las siguientes estrategias para recopilar la informacion, 1) reflexiones de la investigadora en el proceso de diseno y desarrollo de las lecciones adaptadas, que se registraron en un diario reflexivo. 2) entrevista semiestructurada luego de haber trabajado las lecciones de aprendizaje adaptadas con los participantes. 3) observaciones y notas de la investigadora del trabajo de los participantes. Para obtener la informacion de los participantes se obtuvo los permisos institucionales necesarios; se seleccionaron los participantes y se validaron los instrumentos; se realizo el desarrollo de las lecciones adaptadas con los participantes; y finalmente, se analizo la informacion obtenida. El diseno de las lecciones de aprendizaje adaptadas se hizo siguiendo las recomendaciones curriculares de los temas de matematicas aplicados en el curso de Astronomia Descriptiva realizado por la investigadora durante su semestre de internado. El testimonio de las voces de los participantes se obtuvo del proceso de desarrollo de las lecciones de aprendizaje adaptadas de temas seleccionados de conceptos matematicos requeridos en el curso de Astronomia Descriptiva y de la entrevista semiestructurada con los participantes, luego de haber trabajado las lecciones de aprendizaje. Para el desarrollo de las lecciones de aprendizaje, se utilizaron materiales tactiles adaptados, materiales tactiles disenados y materiales disponibles comercialmente. Los textos de las lecciones se imprimieron en tinta y en Braille. Se exhorta a disenar y desarrollar estrategias de ensenanza accesibles, considerando como recursos para evaluar su efectividad a personas con impedimentos visuales. El utilizar estrategias de aprendizaje accesibles de acuerdo a las necesidades individuales de los estudiantes, contribuye para que los estudiantes con impedimentos visuales descubran, exploren, investiguen y formulen sus propias conclusiones durante su proceso de aprendizaje.

Isidro Villamizar, Gloria Maria

32

Bodybuilding als Sinnsystem  

Microsoft Academic Search

\\u000a Bodybuilder sind körperlich stigmatisierte Normabweichler. Sie werden nicht nur als unintelligent, sondern auch gern als exhibitionistisch,\\u000a narzisstisch, monströs, ekelhaft, abscheulich, widerwärtig, abstoßend – und was der emphatischen Belegungen mehr sind – betrachtet.\\u000a Sie gelten als aufgeblasene, angeberische, eitle „Popanze“, die mit ihren Muskeln „überhaupt nichts“ anzufangen wüssten, denen\\u000a bei jeder Dauerbelastung die Luft wegbleibe und die zu allem Überfluss (wegen

Anne Honer

33

Beamte, die sich als \\  

Microsoft Academic Search

7 Sicherheitspolitik ist also keineswegs wertneutral. Dies betrifft sowohl das Ziel dieser Politik, als auch die Mittel, deren man sich zum Erreichen dieses Ziels bedient. Werden etwa territoriale Integrität und Souveränitäts- wahrung als Kernwerte nationaler Sicherheit angenommen, ent- spricht dies einer normativen politischen Ausrichtung. Im Vorder- grund steht damit die Bewahrung des bestehenden National- staats und nicht beispielsweise die Bildung

Walter Lippmann

34

Ventilatory Control in ALS  

PubMed Central

Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease. ALS selectively causes degeneration in upper and lower (spinal) motor neurons, leading to muscle weakness, paralysis and death by ventilatory failure. Although ventilatory failure is generally the cause of death in ALS, little is known concerning the impact of this disorder on respiratory motor neurons, the consequences of respiratory motor neuron cell death, or the ability of the respiratory control system to “fight back” via mechanisms of compensatory respiratory plasticity. Here we review known effects of ALS on breathing, including possible effects on rhythm generation, respiratory motor neurons, and their target organs: the respiratory muscles. We consider evidence for spontaneous compensatory plasticity, preserving breathing well into disease progression despite dramatic loss of spinal respiratory motor neurons. Finally, we review current and potential therapeutic approaches directed toward preserving the capacity to breathe in ALS patients. PMID:23692930

Nichols, Nicole L.; Van Dyke, J.; Nashold, L.; Satriotomo, I.; Suzuki, M.; Mitchell, G.S.

2015-01-01

35

ALS2 mutations  

PubMed Central

Objective: To determine the genetic etiology in 2 consanguineous families who presented a novel phenotype of autosomal recessive juvenile amyotrophic lateral sclerosis associated with generalized dystonia. Methods: A combination of homozygosity mapping and whole-exome sequencing in the first family and Sanger sequencing of candidate genes in the second family were used. Results: Both families were found to have homozygous loss-of-function mutations in the amyotrophic lateral sclerosis 2 (juvenile) (ALS2) gene. Conclusions: We report generalized dystonia and cerebellar signs in association with ALS2-related disease. We suggest that the ALS2 gene should be screened for mutations in patients who present with a similar phenotype. PMID:24562058

Schneider, Susanne A.; Carr, Lucinda; Deuschl, Guenther; Hopfner, Franziska; Stamelou, Maria; Wood, Nicholas W.; Bhatia, Kailash P.

2014-01-01

36

Amyotrophic Lateral Sclerosis (ALS)  

MedlinePLUS

... with ALS may eventually consider forms of mechanical ventilation (respirators). What is the prognosis? Regardless of the ... the muscles of the respiratory system weaken. Although ventilation support can ease problems with breathing and prolong ...

37

What Is ALS?  

MedlinePLUS

... cells in the brain and the spinal cord. Motor neurons reach from the brain to the spinal cord ... throughout the body. The progressive degeneration of the motor neurons in ALS eventually leads to their death. When ...

38

Genetic Testing for ALS  

MedlinePLUS

... Share Print Familial Amyotrophic Lateral Sclerosis (FALS) and Genetic Testing By Deborah Hartzfeld, MS, CGC, Certified Genetic ... guarantee a person will develop symptoms of ALS. Genetic Counseling If there is more than one person ...

39

Leakage current behaviors of Al/ZrO2/Al and Al/YSZ/Al devices  

NASA Astrophysics Data System (ADS)

The leakage current behaviors of Al/ZrO2/Al and Al/yttria stabilized zirconia (YSZ)/Al devices are investigated for resistive random access memory (RRAM) applications. A silicon oxide layer (450 nm) is first formed on a Si wafer by thermal oxidation. Onto it an Al bottom electrode (270 nm), a ZrO2 or YSZ nano-film (75 nm), and an Al top electrode (270 nm) are sequentially deposited by sputtering. These RRAM devices exhibit ohmic behaviors in the low-field region, while Schottky and Poole–Frenkel emissions take over in the high-field regions. Both the Schottky and trap barrier levels are decreased when monoclinic ZrO2 is replaced by cubic YSZ in the metal/oxide/metal structure. This is attributed not only to the higher symmetry crystal structure and lower binding energy of YSZ, but also to the formation of more oxygen vacancies and their re-distribution associated with yttria doping.

Yeh, Tsung-Her; Lin, Ruei-De; Cherng, Bo-Ruei; Cherng, Jyh-Shiarn

2015-01-01

40

Rapidly solidified NiAl and FeAl  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

41

Rapidly solidified NiAl and FeAl  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

42

Negative ion photodetachment spectroscopy of the Al3O2 , Al3O3 , Al4Ox , Al5Ox (x = 35), Al6O5 , and Al7O5 clusters  

E-print Network

Negative ion photodetachment spectroscopy of the Al3O2 , Al3O3 , Al4Ox , Al5Ox (x = 3­5), Al6O5 , and Al7O5 clusters Giovanni Meloni, Michael J. Ferguson and Daniel M. Neumark Department of Chemistry as an Advance Article on the web 9th September 2003 The Al3O2 , Al3O3 , Al4Ox , Al5Ox (x ¼ 3­5), Al6O5 , and Al7

Neumark, Daniel M.

43

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

44

MDA ALS Caregiver's Guide  

MedlinePLUS

... cure.” And it’s really hard work. It involves learning about new tasks and equipment, while going through the emotions that arise when a loved one has a progressive, debilitating illness. These pages contain practical and emotional strategies for being an effective caregiver. The MDA ALS ...

45

Ausbildung als zentrale Aufgabe  

NASA Astrophysics Data System (ADS)

Anders als Lesen und Schreiben zählen Grundkenntnisse in Statistik heute noch nicht zu den Voraussetzungen einer sinnvollen Teilhabe am Sozialgeschehen. Und auch in der akademischen Statistik-Ausbildung gibt es noch einiges zu tun. Das vorliegende Kapitel zeichnet die Geschichte dieser akademischen Ausbildung an deutschen Universitäten nach dem zweiten Weltkrieg nach, stellt aktuelle Defizite vor und weist auf mögliche Verbesserungen hin.

Krämer, Walter; Schmerbach, Sibylle

46

Smith et al Supporting Information  

E-print Network

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

Jarvis, Erich D.

47

Extensión del Formalismo de Orbitales de Defecto Cuántico al tratamiento del efecto Stark (SQDO).  

NASA Astrophysics Data System (ADS)

El estudio experimental de las interacciones de átomos Rydberg altamente excitados con campos eléctricos ha experimentado un creciente interés durante las dos últimas décadas debido, en gran medida, al desarrollo de nuevas técnicas para crear y estudiar átomos Rydberg en el laboratorio. Acompañando a estas nuevas técnicas experimentales, es necesario el desarrollo de modelos teóricos que nos permitan contrastar sus medidas y conocer mejor los fundamentos de los mismos. Desde el punto de vista teórico el conocimiento del desdoblamiento de los niveles energéticos de un átomo en función de la magnitud del campo eléctrico aplicado (lo que se conoce como mapa Stark) es el mejor punto de partida para la descripción del sistema y un prerrequisito fundamental para el cálculo de distintas propiedades atómicas en presencia del campo eléctrico tales como intensidades de transición, umbrales de ionización de campo eléctrico, tiempos de vida, posición y anchura de cruces evitados, etc. En este trabajo presentamos la adaptación del método de orbitales de defecto cuántico [1,2,3] al tratamiento del efecto Stark (SQDO) [4] y su aplicación al cálculo de los desdoblamientos energéticos y fuerzas de oscilador de estados Rydberg en los átomos de Li, Na y K. El propósito de este estudio es, por un lado, desarrollar métodos fiables para la determinación de propiedades atómicas en presencia de campos eléctricos y, por otro, mostrar la fiabilidad de las funciones de onda QDO en la descripción del efecto Stark en sistemas atómicos.

Menéndez, J. M.; Martín, I.; Velasco, A. M.

48

/Al-Si Composite  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

49

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.

50

ALS insertion devices  

SciTech Connect

The Advanced Light Source (ALS), the first US third generation synchrotron radiation source, is currently under construction at the Lawrence Berkeley Laboratory. The low-emittance, 1.5 GeV electron storage ring and the insertion devices are specifically designed to produce high brightness beams in the UV to soft X-Ray range. The planned initial complement of insertion devices includes four 4.6 m long undulators, with period lengths of 3.9 cm, 5.0 cm (2) and 8.0 cm, and a 2.9 m long wiggler of 16 cm period length. Undulator design is well advanced and fabrication has begun on the 5.0 cm and 8.0 cm period length undulators. This paper discusses ALS insertion device requirements; general design philosophy; and design of the magnetic structure, support structure/drive systems, control system and vacuum system. 18 refs., 9 figs., 5 tabs.

Hoyer, E.; Chin, J.; Halbach, K.; Hassenzahl, W.V.; Humphries, D.; Kincaid, B.; Lancaster, H.; Plate, D.

1990-11-01

51

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

52

26Al measurements with VERA  

NASA Astrophysics Data System (ADS)

The Vienna Environmental Research Accelerator (VERA) is a 3-MV Pelletron tandem mass spectrometer system. Since July 1996, extensive tests with 26Al detection were performed. Systematic investigations of reproducibility, transmission, overall efficiency etc. are necessary for a new facility such as VERA in order to come up with reliable results. To this end several different 26Al standards with an 26Al/ 27Al isotopic ratio between 5 × 10 -10 and 1 × 10 -12 were used. The results of these investigations revealed no systematic deviation beyond counting statistics. In order to determine the cross section for the 27Al(n,2n) 26Al reaction Al-metal samples with 26Al produced from neutron irradiation were measured and compared with 26Al standards.

Wallner, A.; Golser, R.; Kutschera, W.; Priller, A.; Steier, P.; Vonach, H.; Wild, E.

1998-04-01

53

Frequently Asked Questions about ALS and the ALS Registry  

MedlinePLUS

... Can a researcher access National ALS Registry data? How will you be sure that you have as many persons ... National ALS Registry web site. Back to Top How will you be sure that you have as many persons ...

54

Amyotrophic Lateral Sclerosis (ALS)  

NSDL National Science Digital Library

This patient education program explains amyotrophic lateral sclerosis (ALS or Lou Gehrig's Disease) including the causes, symptoms, diagnosis and treatment options. This resource is a MedlinePlus Interactive Health Tutorial from the National Library of Medicine, designed and developed by the Patient Education Institute. NOTE: This tutorial requires a special Flash plug-in, version 4 or above. If you do not have Flash, you will be prompted to obtain a free download of the software before you start the tutorial. You will also need an Acrobat Reader, available as a free download, in order to view the Reference Summary.

Patient Education Institute

55

Al Jazirah, Sudan  

NASA Technical Reports Server (NTRS)

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

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

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

2008-01-01

56

Al(+)-ligand binding energies  

NASA Technical Reports Server (NTRS)

Ab initio calculations are used to optimize the structure and determine the binding energies of Al(+) to a series of ligands. For Al(+)-CN, the bonding was found to have a large covalent component. For the remaining ligands, the bonding is shown to be electrostatic in origin. The results obtained for Al(+) are compared with those previously reported for Mg(+).

Sodupe, M.; Bauschlicher, Charles W., Jr.

1991-01-01

57

Studies of 27Al NMR in EuAl4  

NASA Astrophysics Data System (ADS)

EuAl4 orders antiferromagnetically at TN ? 16 K with an effective magnetic moment of 8.02 ?B. In the paramagnetic phase, the magnetic susceptibility of EuAl4 follows the Curie-Weiss law with a positive Curie-Weiss temperature ?P = +14 K. The antiferromagnetic state is changed into the field induced ferromagnetic state at a critical field Hc of approximately 2 T. In order to microscopically investigate the magnetic and electronic properties in EuAl4, the NMR measurements of EuAl4 have been carried out at temperatures between 2 and 300 K, applying an external magnetic field of approximately 6.5 T. The 27Al NMR spectra corresponding to Al(I) and Al(II) sites are obtained. From the 27Al NMR spectra, the isotropic part Kiso and anisotropic part Kaniso of Knight shift, and nuclear quadrupole frequncy ?Q are obtained. The Kiso and Kaniso shift to negative side with decreasing temperature due to the RKKY interaction. These temperature dependences follow the Curie-Weiss law with ?P = +14 K, which is consistent with that of the magnetic susceptibility. From the K – ? plot, the values of the hyperfine fields Hhf_iso and Hhf_aniso are -3.231 and -0.162 kOe/?B for Al(I) site, and -1.823 and -0.264 kOe/?B for Al(II) site, respectively. The values of ?Q of 27Al nucleus for Al(I) and Al(II) sites are approximately 0.865 and 0.409 MHz, respectively. The nuclear relaxation time T1 of 27Al NMR for both sites is almost constant in the paramagnetic phase, while the value of 1/T1 is abruptly decreased in the ordered ferromagnetic state.

Niki, H.; Nakamura, S.; Higa, N.; Kuroshima, H.; Toji, T.; Yogi, M.; Nakamura, A.; Hedo, M.; Nakama, T.; ?nuki, Y.; Harima, H.

2015-03-01

58

Al Mashriq: Lebanon  

NSDL National Science Digital Library

Part of the Al-Mashriq online Web resource for countries located in the Levant, this site is devoted to providing a host of materials, thematically organized, about the country of Lebanon. Persons seeking to read a bit about Lebanon's early history will want to read the first chapter of Kamal Salibi's "A House of Many Mansions-The History of Lebanon," which is provided here. For those looking for a geographic orientation to the landscape of Lebanon, an interactive map provides a number of photographs and brief remarks on various important cities and cultural sites, such as Beirut and the Roman temples at Baalbak. Along with these sections, the site also offers thematic sections devoted to education, food, maps, money, politics, and religion that will be useful to those students looking for background information on Lebanon.

59

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

E-print Network

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

Alfonseca, Manuel

60

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

61

Characteristics of CeCoIn5/Al/AlOx/Nb and CeCoIn5/Al/AlOx/Al Tunnel Junctions  

SciTech Connect

We report characteristics of CeCoIn{sub 5}/Al/AlO{sub x}/Nb and CeCoIn{sub 5}/Al/AlO{sub x}/Al tunnel junctions fabricated on the (0 0 1) surface of CeCoIn{sub 5} crystal platelets. The main result of this work is the observation of a low Josephson current (as compared with that expected from the Ambegaokar-Baratoff formula), which is consistent with idea that the order parameter in the heavy-fermion superconductor CeCoIn{sub 5} has unconventional pairing symmetry.

Petrovic, C.; Nevirkovets, I.P.; Chernyashevskyy, O.; Hu, R.; Ketterson, J.B.; Sarma, B.K.

2009-03-03

62

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

E-print Network

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

Sandini, Giulio

63

(12) United States Patent Harvey et al.  

E-print Network

(12) United States Patent Harvey et al. (54) ANALYZING RETURN ON INVESTMENT OF ADVERTISING US 2009/0259518 Al Oct. 15,2009 Int. Cl. G06F 17/30 (2006.01) G07G 1/00 (2006.01) U.S. Cl et al. 911980 Block et al. 511982 Eskin et al. 1111982 Barber et al. 711985 Block et al. 111996

Shamos, Michael I.

64

Anno accademico 2013/2014 Modulo di adesione al piano di studio di completamento del percorso formativo  

E-print Network

Laboratorio di fisica computazionale I 6 INF/01 Elettromagnetismo 12 FIS/01 Laboratorio di elettromagnetismo e di calcolo 6 INF/01 Meccanica 12 FIS/01 Chimica 6 CHIM/03 Laboratorio di meccanica 12 FIS/01 Analisi Meccanica statistica 6 FIS/02 Laboratorio di segnali e sistemi 9 FIS/01 Ottica e laboratorio 9 FIS/01

Roma "La Sapienza", Università di

65

ALS ACT (Accelerated Therapeutics), The ALS Association, Northeast ALS Consortium, and the ALS Finding A Cure Foundation  

E-print Network

pharmaceutical, biotherapeutic/biotechnology companies, academic members of the NEALS Consortium, and ALS through NEALS: Project Management Grants & Contracts Management Data Management Study Monitoring Document Review, and Ongoing Site Management Site Trainings: Good Clinical Practice, Regulatory Compliance

MacMillan, Andrew

66

In Memory of Al Cameron  

E-print Network

Al Cameron, who died recently (October 3, 2005) at 80, was one of the giants in astrophysics. His insights were profound and his interests were wide-ranging. Originally trained as a nuclear physicist, he made major contributions in a number of fields, including nuclear reactions in stars, nucleosynthesis, the abundances of the elements in the Solar System, and the origin of the Solar System and the Moon. In 1957, Cameron and, independently, Burbidge, Burbidge, Fowler and Hoyle, wrote seminal papers on nuclear astrophysics. Most of our current ideas concerning element formation in stars have followed from those two pioneering and historical works. Al also made many contributions in the field of Solar System physics. Particularly noteworthy in this regard was Cameron's work on the formation of the Moon. Al was also a good friend and mentor of young people. Al Cameron will be missed by many in the community both for his scientific contributions and for his friendship.

John J. Cowan; James W. Truran

2006-11-27

67

Developmental Cell Abbott et al.  

E-print Network

seam cell nuclei. #12;#12;Developmental Cell September Abbott et al. Supplemental Experimental Procedures Detection expression is observed at the L1 stage in multiple cell types, including seam cells and neurons (n). (B, D

Bartel, David

68

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

NASA Technical Reports Server (NTRS)

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 directly by Knudsen effusion-cell mass spectrometry with an instrument configured for a multiple effusion-cell vapor source (multi-cell KEMS). Second law enthalpies of vaporization of Al(g) and Al2O(g) together with activity measurements show that Al(l)+ZrO2(s) is thermodynamically equivalent to Al(l)+Al2O3(s), indicating Al(l) remained pure and Al2O3(s) was present in the ZrO2-cell. Subsequent observation of the Al(l)/ZrO2 and vapor/ZrO2 interfaces revealed a thin Al2O3-layer had formed, separating the ZrO2-cell from Al(l) and Al(g)+Al2O(g), effectively transforming it into an Al2O3 effusion-cell. This behavior agrees with recent observations made for Beta-NiAl(Pt) alloys measured in ZrO2 effusion-cell.

Copland, Evan

2004-01-01

69

Corrosion Behavior of Al-Al3Ni and Al-Al2Cu Functionally Graded Materials Fabricated by a Centrifugal Method  

NASA Astrophysics Data System (ADS)

Intermetallic compounds, such as Al3Ni and Al2Cu, are effective for enhancing the mechanical properties of an alloy. Al-Al3Ni and Al-Al2Cu functionally graded materials (FGMs) might be attractive materials for advanced materials. Al-Al3Ni and Al-Al2Cu FGMs were fabricated by a centrifugal method; the centrifugal method is an extremely effective method for fabricating FGMs. Al-Al3Ni and Al-Al2Cu FGMs that had a graded distribution of intermetallic compounds could be produced by this in-situ centrifugal method. Particle size, particle shape and the distribution of intermetallic compounds were controlled by varying the content of the alloy element (Ni, Cu) in the master alloy, the cooling rate in casting and the gravity number. The casting mechanism is explained in terms of the microstructures of the Al-Al3Ni and Al-Al2Cu FGMs fabricated by this method. The corrosion behavior of the FGMs was investigated by electrochemical analysis. Polarization curves of the FGMs in a borate solution were measured by a potentiodynamic method. The presence of Al2Cu exerted a larger effect on the corrosion behavior of the FGMs than Al3Ni. Analysis of the polarization curve parameters was effective for evaluating the corrosion resistance of the FGMs.

Noda, Kazuhiko; Miyahara, Keita; Watanabe, Yoshimi

2008-02-01

70

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, 2014

...Front, Jabhat al- Nusrah, Jabhet al-Nusra, The Victory Front, Al Nusrah Front...aka Jabhat al-Nusrah, aka Jabhet al-Nusra, aka The Victory Front, aka Al...Front, Jabhat al-Nusrah, Jabhet al-Nusra, The Victory Front, Al Nusrah...

2012-12-11

71

ALS Association's Patient Bill of Rights for People Living with ALS  

MedlinePLUS

... Caregivers Newly Diagnosed ALS Registry Military Veterans Augmentative Communication Caregivers Resources ALS Insight Newsletter Living with ALS Manuals ALS Association Brochures Webinars Our Videos Factsheets Library Order Form Products to Aid in ...

72

Uranium cobalt tetraaluminide, UCoAl4.  

PubMed

The structure of UCoAl(4) can be viewed as a succession of atomic layers, with the compositions UCoAl and Al(3), that alternate along the c axis. The packing within the pure Al layer at z = 1/2 results from edge-sharing of triangles, squares and pentagons of Al atoms. Two successive Al(3) layers thus define pentagonal, square-based and trigonal prisms which are centred at z = 0 by the U, Co and remaining Al atoms. UCoAl(4) is a high-temperature phase that is only observed in as-cast samples. PMID:14712016

Stêpien-Damm, J; Tougait, O; Zaremba, V I; Noël, H; Troc, R

2004-01-01

73

AlN/Fe/AlN nanostructures for magnetooptic magnetometry  

SciTech Connect

AlN/Fe/AlN/Cu nanostructures with ultrathin Fe grown by sputtering on Si substrates are evaluated as probes for magnetooptical (MO) mapping of weak currents. They are considered for a laser wavelength of ??=?410?nm (3.02?eV) and operate at oblique light incidence angles, ?{sup (0)}, to enable detection of both in-plane and out-of-plane magnetization. Their performance is evaluated in terms of MO reflected wave electric field amplitudes. The maximal MO amplitudes in AlN/Fe/AlN/Cu are achieved by a proper choice of layer thicknesses. The nanostructures were characterized by MO polar Kerr effect at ?{sup (0)}???5° and longitudinal Kerr effect spectra (?{sup (0)}?=?45°) at photon energies between 1 and 5?eV. The nominal profiles were refined using a model-based analysis of the spectra. Closed form analytical expressions are provided, which are useful in the search for maximal MO amplitudes.

Lišková-Jakubisová, E., E-mail: liskova@karlov.mff.cuni.cz; Viš?ovský, Š. [Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, 12116 Prague 2 (Czech Republic); Široký, P.; Hrabovský, D.; Pištora, J. [Nanotechnology Center, Technical University of Ostrava, 17. listopadu 15/2172, 70833 Ostrava Poruba (Czech Republic); Harward, I.; Celinski, Z. [Center for Magnetism and Magnetic Nanostructures, University of Colorado at Colorado Springs, 1420 Austin Bluffs Pkwy., Colorado Springs, Colorado 80918 (United States)

2014-05-07

74

Dopant-Free GaN/AlN/AlGaN Radial Nanowire Heterostructures as High  

E-print Network

Dopant-Free GaN/AlN/AlGaN Radial Nanowire Heterostructures as High Electron Mobility Transistors, 2006 ABSTRACT We report the rational synthesis of dopant-free GaN/AlN/AlGaN radial nanowire-organic chemical vapor deposition (MOCVD). Transmission electron microscopy (TEM) studies reveal that the GaN/ AlN/AlGaN

Li, Yat

75

Modulation-doped (Al,Ga)As/AlAs superlattice: Electron transfer into AlAs  

SciTech Connect

A modulation-doped superlattice of n-(Al,Ga)As and undoped AlAs has been grown by molecular beam epitaxy. At cryogenic temperatures, electrons transfer into the undoped AlAs layers and enhanced mobilities as high as 1000 cm/sup 2//Vs are observed for the first time. It is shown that by properly accounting for the depth of the donor level in modulation-doped heterostructures reasonably good limits can be set on the gamma point conduction-band discontinuity at the heterojunction. It is found that this discontinuity is approximately 60--65% of the band-gap difference between the two alloys, in good agreement with other recent determinations.

Drummond, T.J.; Fritz, I.J.

1985-08-01

76

Microstructure Evolution and Mechanical Properties of Al/Al-Mg/Al composite sheet metals  

NASA Astrophysics Data System (ADS)

Two different types of aluminum alloys of AA1050 and AA5182 were used to manufacture Al/Al-Mg/Al composite sheet metals by roll bonding technology at room temperature. The composite sheet metals were annealed at 400 °C and carried out uniaxial tension tests to investigate mechanical properties. Macroscopic mechanical properties are strongly dependent on the volume (or thickness) fraction of two component layers. Microstructure and texture evolution were also investigated during roll bonding process. The AA1050 sheets located in the outer layer mainly consist of shear texture components and the AA5182 sheet located in the center layer consists of plane strain texture components. With differential speeds of the top and bottom rolls, roll bonding was also carried out. Elongation along the RD and TD was improved at a speed difference of approximately 10%-20%.

Cho, Jaehyung; Kim, Su-Hyeon; Kim, Hyoung-Wook; Lim, Cha-Yong; Kim, Eun-Young; Choi, Shi-Hoon

2011-08-01

77

Lynch et al. Proceedings 109  

E-print Network

Lynch et al. Proceedings 109 Insect­Fire Interactions in Yellowstone National Park: The Influence@fas.harvard.edu) Roy A. Renkin Yellowstone Center for Resources, P.O. Box 168, Yellowstone National Park, WY 82190 (307 of mountain pine beetle (Dendroctonus ponderosae Hopkins) activity within Yellowstone National Park, Wyoming

Moorcroft, Paul R.

78

AnnuAl report JAhresbericht  

E-print Network

AnnuAl report JAhresbericht rApport d'Activités 2010 #12;#12;1LE MOT DU RECTEUR LE MOT DU RECTEUR of laboratory space. This will change in the year 2011 with the inauguration of the LCSB building in Belval GOUVERNANCE RAPPORT ANNUEL 2010 LE CONSEIL DE GOUVERNANCE P. 05 L'�QUIPE RECTORALE P. 11 LES ORGANES

van der Torre, Leon

79

Transformer Abdullah Al-Otaibi  

E-print Network

Transformer Abdullah Al-Otaibi ID#242374 Section#2 Abstract- this is a brief description for transformer and how it works. I. DEFINITION A transformer is a device that transfers electrical energy from of the transformer in 1831. The transformer is used by Faraday only to demonstrate the principle of electromagnetic

Masoudi, Husain M.

80

Dynamic Modeling of ALS Systems  

NASA Technical Reports Server (NTRS)

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

Jones, Harry

2002-01-01

81

Sobrevivir al cáncer: comer bien  

Cancer.gov

Sobrevivir al cáncer: comer bien Por el Instituto Nacional del Cáncer Bethesda, MD. - Más de 13 millones de personas que viven en Estados Unidos han recibido un diagnóstico de cáncer. Muchas de las personas que han tenido cáncer quieren seguir una

82

(12) United States Patent Reardan et al.  

E-print Network

(12) United States Patent Reardan et al. (54) SENSITIVE DRUG DISTRIBUTION SYSTEM AND METHOD (75 2004/0117205 Al Jun. 17,2004 (51) Int. Cl. G06Q 10/00 (2006.01) (52) U.S. Cl/231 4,976,351 A 1211990 Mangini et al. 5,737,539 A * 411998 Edelson et al. ................. 705/3 5

Shamos, Michael I.

83

(12) United States Patent Likourezos et al.  

E-print Network

(12) United States Patent Likourezos et al. (54) SYSTEM AND METHOD FOR AUTOMATICALLY EFFECTING Publication Data US 2002/0095376 Al Jul. 18, 2002 Related U.S. Application Data Continuation Altman et al. ................ 705/36 5,715,314 A 211998 Payne et al. 5,794,219 A 811998 Brown 5

Shamos, Michael I.

84

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. PMID:9765564

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

1998-01-01

85

AnnuAl report JAhresbericht  

E-print Network

AnnuAl report JAhresbericht rApport d'Activités 2011 #12;1LE MOT DU RECTEUR Le mot du RecteuR Le'Université puisqu'il y existe une diversité de perspectives par rapport aux personnes ou aux structures devant for Systems Biomedicine moved into its new building in Belval. Belval is slowly becoming the fourth campus

van der Torre, Leon

86

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

NASA Astrophysics Data System (ADS)

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

Liang, Song-Mao; Schmid-Fetzer, Rainer

2014-11-01

87

The Collections - Dar al-Athar al-Islamiyyah  

NSDL National Science Digital Library

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

88

Thermal expansion of gehlenite, Ca 2 Al[AlSiO 7 ], and the related aluminates Ln CaAl[Al 2 O 7 ] with Ln =Tb, Sm  

Microsoft Academic Search

The thermal expansion of gehlenite, Ca2Al[AlSiO7], (up to T=830 K), TbCaAl[Al2O7] (up to T=1,100 K) and SmCaAl[Al2O7] (up to T=1,024 K) has been determined. All compounds are of the melilite structure type with space group\\u000a $$P\\\\bar {4}2_1\\\\,m.$$ Thermal expansion data was obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg (Germany). The

L. Peters; K. Knorr; M. Knapp; W. Depmeier

2005-01-01

89

Thermal expansion of gehlenite, Ca2Al[AlSiO7], and the related aluminates LnCaAl[Al2O7] with Ln = Tb, Sm  

Microsoft Academic Search

The thermal expansion of gehlenite, Ca2Al[AlSiO7], (up to T=830 K), TbCaAl[Al2O7] (up to T=1100 K) and SmCaAl[Al2O7] (up to T=1024 K) has been determined. All compounds are of the melilite structure type with space group P{bar{4}}21m. Thermal expansion data were obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg

L. Peters; K. Knorr; M. Knapp; W. Depmeier

2005-01-01

90

Thermal expansion of gehlenite, Ca 2 Al[AlSiO 7 ], and the related aluminates Ln CaAl[Al 2 O 7 ] with Ln = Tb, Sm  

Microsoft Academic Search

The thermal expansion of gehlenite, Ca2Al[AlSiO7], (up to T=830 K), TbCaAl[Al2O7] (up to T=1100 K) and SmCaAl[Al2O7] (up to T=1024 K) has been determined. All compounds are of the melilite structure type with space group\\u000a $$P{\\\\bar{4}}2_{1}m.$$ Thermal expansion data were obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches\\u000a Elektronen Synchrotron (DESY) in Hamburg (Germany). The thermal

L. Peters; K. Knorr; M. Knapp; W. Depmeier

2005-01-01

91

NiAl-base composite containing high volume fraction of AlN for advanced engines  

NASA Technical Reports Server (NTRS)

A particulate reinforced NiAl-AlN composite alloy has a NiAl matrix and greater than about 13 volume percent fine particles of AlN within the matrix. The particles preferably have a diameter from about 15 nanometers to about 50 nanometers. The particulate reinforced NiAl-AlN composite alloy may be prepared by cryomilling prealloyed NiAl in liquid nitrogen using grinding media having a diameter of from about 2 to 6 mm at an impeller speed of from about 450 RPM to about 800 RPM. The cryomilling may be done for a duration of from about 4 hours to about 20 hours to obtain a cryomilled powder. The cryomilled powder may be consolidated to form the particulate reinforced NiAl-AlN composite alloy. The particulate reinforced alloy can further include a toughening alloy. The toughening alloy may include NiCrAlY, FeCrAlY, and FeAl.

Hebsur, Mohan (inventor); Whittenbeger, John D. (inventor); Lowell, Carl F. (inventor)

1994-01-01

92

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

E-print Network

) of the true breakdown electric field Eb across the dielectric. By modeling this interface contribution the dielectric, this cor- responds to a surface charge density on the aluminum elec- trodes at breakdown givenContribution of interface capacitance to the electric-field breakdown in thin-film Al­AlOx ­Al

Hebard, Arthur F.

93

Isolde Lasoen ALS ontsnapt aan uitsluiting  

E-print Network

gezet kooitje kan gepord worden tot vermaak van het volk. Een Guantanamo Bay voor huisdieren, zeg maar, al hoef je voor een verblijf in Guantanamo geen 6 of 8 euro te beta- len, gewoon hoesten als een

94

(12) United States Patent Vertes et al.  

E-print Network

(12) United States Patent Vertes et al. (54) LASER DESORPTION IONIZATION AND PEPTIDE SEQUENCING. (21) Appl. No.: 11/674,671 (22) Filed: Feb. 14,2007 (65) Prior Publication Data US 2009/0321626 Al Dec Suizdak et al. 6,589,485 B2 7/2003 Koster 6,794,196 B2 912004 Fonash et al. 6,846,681 B2 112005 Buriak et

Vertes, Akos

95

(12) United States Patent Vertes et al.  

E-print Network

(12) United States Patent Vertes et al. (54) THREE-DIMENSIONAL MOLECULAR IMAGING BY INFRARED LASER/0012831 Al Jan. 21, 2010 Related U.S. Application Data (63) Continuation-in-part of application No. 121176,656,690 B2 6,744,046 B2 6,991,903 B2 7,084,396 B2 12/2003 Crooke et al. 612004 Valaskovic et al. 112006 Fu

Vertes, Akos

96

(12) United States Patent Fallon et al.  

E-print Network

(12) United States Patent Fallon et al. (54) SYSTEM AND METHOD FOR DATA FEED ACCELERATION/131,631 (22) Filed: Jun. 2,2008 (65) Prior Publication Data US 200910287839 Al Nov. 19,2009 Related U References Cited U.S. PATENT DOCUMENTS 3,394,352 A 7/1968 Wernikoff et al. 3,490,690 A 111970 Apple et al. 4

Shamos, Michael I.

97

(12) United States Patent Reardan et al.  

E-print Network

(12) United States Patent Reardan et al. (54) SENSITIVE DRUG DISTRIBUTION SYSTEM AND METHOD (75 US 2005/0090425 Al Apr. 28, 2005 Related U.S. Application Data Division of application No.1 0,847,764 A 711989 Halvorson 4,976,351 A 1211990 Mangini et al. 5,737,539 A 411998 Edelson et al. 5,845,255 A 1211998

Shamos, Michael I.

98

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

SciTech Connect

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

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

2013-02-15

99

Effect of Al-Si-Al and Al-Si-Si-Al Pairs in the ZSM-5 Zeolite Framework on the 27 NMR Spectra. A Combined High-Resolution 27  

E-print Network

Effect of Al-Si-Al and Al-Si-Si-Al Pairs in the ZSM-5 Zeolite Framework on the 27 Al NMR Spectra. A Combined High-Resolution 27 Al NMR and DFT/MM Study Jiri´ Dedecek, Stepan Sklenak,*, Chengbin Li, Blanka of the presence of Al-O-Si-O-Al and Al-O-Si-O-Si-O-Al sequences in the ZSM-5 zeolite framework on the local

Sklenak, Stepan

100

United States Patent [19] Church et al.  

E-print Network

United States Patent [19] Church et al. [54] CHARACTERIZATION OF INDIVIDUAL POLYMER MOLECULES BASED al.. "ANeutral Amino Acid Change in Segment TIS4 Dramatically Alters the Gating Properties of the Volt- age-Dependent Sodium Channel". 1990, Proc. Natl. Acad. Sci. USA, 87:323-27. Bensirnon. A.. et al

Church, George M.

101

(12) United States Patent Likourezos et al.  

E-print Network

(12) United States Patent Likourezos et al. (54) SYSTEM AND METHOD FOR EFFECTING A REAL: Nov. 14, 2001 (65) Prior Publication Data US 2002/0095377 Al Jul. 18, 2002 Related U.S. Application Cited U.S. PATENT DOCUMENTS 4,799,156 A 4,876,648 A 111989 Shavit et al. 1011989 Lloyd 102 102 111111

Shamos, Michael I.

102

Klimes et al. 1997 Dioscorea japonica  

E-print Network

and Silvertown 2004 Charpentier et al. 2000 Eckert 2000 Maynard Smith 1980 Utricularia australis f. tenuicaulis U. macrorhiza U. australis F1 Kameyama et al. 2005 Kameyama and Ohara 2006 3 genet #12;262 Barrett et al. 1993, Ohara M (2005) Hybrid origins and F1 dominance in the free-floating, sterile bladderwort, Utricularia

Tomimatsu,, Hiroshi

103

Wear behavior of Al-Al{sub 3}Ti composite manufactured by a centrifugal method  

SciTech Connect

The purpose of the present study was to develop a wear-resistant, light Al-Al{sub 3}Ti composite material. An Al-Al{sub 3}Ti composite specimen was machined from a thick-walled tube of Al-Al{sub 3}Ti functionally graded material (FGM) manufactured by the centrifugal method from a commercial ingot of Al-5 mass% Ti master alloy. The alloy was heated to a temperature where solid Al{sub 3}Ti particles resided in a liquid Al matrix, and then the centrifugal method was carried out. Al{sub 3}Ti particles in a commercial alloy ingot exist as platelets, and this shape was maintained through the casting. Three kinds of wear specimens were prepared, taking into account the morphology of the Al{sub 3}Ti particles in the thick-walled FGM tube; the Al{sub 3}Ti particles were arranged with their platelet planes nearly normal to the radial direction as a result of the applied centrifugal force. The wear resistance of the Al-Al{sub 3}Ti composite was significantly higher than that of pure Al. Wear-resistance anisotropy and dissolution of the Al{sub 3}Ti into the Al matrix at the near-surface region, around 100 {micro}m in depth, were also observed. The mechanism of the supersaturated-layer formation and the origin of the anisotropic wear resistance are discussed.

Watanabe, Yoshimi; Yamanaka, Noboru; Fukui, Yasuyoshi

1999-12-01

104

Systems Engineering Techniques for ALS Decision Making  

NASA Technical Reports Server (NTRS)

The Advanced Life Support (ALS) Metric is the predominant tool for predicting the cost of ALS systems. Metric goals for the ALS Program are daunting, requiring a threefold increase in the ALS Metric by 2010. Confounding the problem, the rate new ALS technologies reach the maturity required for consideration in the ALS Metric and the rate at which new configurations are developed is slow, limiting the search space and potentially giving the perspective of a ALS technology, the ALS Metric may remain elusive. This paper is a sequel to a paper published in the proceedings of the 2003 ICES conference entitled, "Managing to the metric: an approach to optimizing life support costs." The conclusions of that paper state that the largest contributors to the ALS Metric should be targeted by ALS researchers and management for maximum metric reductions. Certainly, these areas potentially offer large potential benefits to future ALS missions; however, the ALS Metric is not the only decision-making tool available to the community. To facilitate decision-making within the ALS community a combination of metrics should be utilized, such as the Equivalent System Mass (ESM)-based ALS metric, but also those available through techniques such as life cycle costing and faithful consideration of the sensitivity of the assumed models and data. Often a lack of data is cited as the reason why these techniques are not considered for utilization. An existing database development effort within the ALS community, known as OPIS, may provide the opportunity to collect the necessary information to enable the proposed systems analyses. A review of these additional analysis techniques is provided, focusing on the data necessary to enable these. The discussion is concluded by proposing how the data may be utilized by analysts in the future.

Rodriquez, Luis F.; Drysdale, Alan E.; Jones, Harry; Levri, Julie A.

2004-01-01

105

Opportunity's 'Rub al Khali' Panorama  

NASA Technical Reports Server (NTRS)

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

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

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

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

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

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

2005-01-01

106

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

E-print Network

. To study the variety of magnetic properties, we use NMR, magnetic susceptibility, specific heat and other methods in this work. The microscopic electronic and magnetic properties of the Al-rich Fe-Al system and Al20V2Eu have been studied via 27Al NMR...

Chi, Ji

2009-05-15

107

Reactive Plasma Spraying of Fine Al2O3/AlN Feedstock Powder  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

108

Comparative Genomic Discovery of miRNAs Grad et al.  

E-print Network

Comparative Genomic Discovery of miRNAs Grad et al. Computational and Experimental Identification throughout the adult life cycle (Feinbaum and Ambros, 1999; Lee et al., 1993; Reinhart et al., 2000 al., 1993; Wightman et al., 1993; Reinhart et al., 2000; Slack et al., 2000). Both lin-4 and let-7

Church, George M.

109

Single crystal growth and characterization of binary stoichiometric and Al-rich Ni 3Al  

Microsoft Academic Search

Binary stoichiometric Ni3Al (Ni–25at% Al) single crystals and Al-rich single-crystal-like (Ni–26at% Al, Ni–27at% Al) alloys that do not contain any ternary additions have been successfully grown for the first time, by using the floating zone method. The quality of the crystals was examined by the Laue X-ray back-reflection method and optical microscopy. The stoichiometric single crystals had good crystallinity. The

D. Golberg; M Demura; T Hirano

1998-01-01

110

Oxidation resistance of intermetallic compounds Al 3 Ti and TiAl  

Microsoft Academic Search

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

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

1989-01-01

111

Cohesive, electronic and magnetic properties of the transition metal aluminides FeAl CoAl and NiAl  

Microsoft Academic Search

Electronic structure calculations using the tight-binding linear muffin tin orbital (TB-LMTO) method have been performed for three transition metal aluminides, viz. FeAl, CoAl and NiAl. The band structures and density of states (DOS), valence electron charge density contours and Fermi surfaces have been obtained and compared with the available experimental results as well as with existing theoretical calculations. The lattice

V. Sundararajan; B. R. Sahu; D. G. Kanhere; P. V. Panat; G. P. Das

1995-01-01

112

First-principles studies of typical long-period superstructures Al 5Ti 3, hAl 2Ti and r-Al 2Ti in Al-rich TiAl alloys  

Microsoft Academic Search

First-principles calculations are performed to study the structural stabilities, electronic and elastic properties of typical long-period superstructures Al5Ti3, h-Al2Ti and r-Al2Ti in Al-rich TiAl alloys together with ?-TiAl. The obtained lattice parameters by relaxation of crystalline cells are in good agreement with the experimental data. The calculated formation enthalpies show that r-Al2Ti has the highest structure stability from energetic point

Ping-Ying Tang; Bi-Yu Tang; Xu-Ping Su

2011-01-01

113

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

114

Crack-Free AlN/GaN Distributed Bragg Reflectors on AlN Templates  

NASA Astrophysics Data System (ADS)

We have demonstrated crack-free 30-pair-AlN/GaN distributed Bragg reflectors (DBRs) grown on AlN templates for the first time. A reasonably high reflectivity of 97.5% was obtained. X-ray diffraction measurements revealed that the AlN templates cause compressive stress in DBRs. At the same time, the AlN/GaN DBRs were found to relax to average AlGaN alloys with AlN mole fractions determined by the thickness ratio of the AlN layer to one pair of AlN and GaN in DBRs regardless of the underlying template, AlN or GaN.

Yagi, Kouta; Kaga, Mitsuru; Yamashita, Kouji; Takeda, Kenichirou; Iwaya, Motoaki; Takeuchi, Tetsuya; Kamiyama, Satoshi; Amano, Hiroshi; Akasaki, Isamu

2012-05-01

115

Charging effect of Al{sub 2}O{sub 3} thin films containing Al nanocrystals  

SciTech Connect

In this work, Al{sub 2}O{sub 3} thin film containing Al nanocrystals (nc-Al) is deposited on Si substrate by radio frequency sputtering to form a metal-insulator-semiconductor structure. Both electron and hole trapping in nc-Al are observed. The charge storage ability of the nc-Al/Al{sub 2}O{sub 3} thin films provides the possibility of memory applications. Charging in the nc-Al also leads to a change in the dc resistance of the thin films, namely, the electron trapping in the nc-Al leads to an increase in the resistance, whereas the resistance is reduced if there is hole trapping in the nc-Al.

Liu, Y. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054 (China); Chen, T. P.; Zhu, W.; Yang, M.; Cen, Z. H.; Wong, J. I. [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Li, Y. B. [Center for Composite Materials, School of Astronautics, Harbin Institute of Technology, P.O. Box 3010, Harbin 150080 (China); Zhang, S. [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Chen, X. B. [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610054 (China); Fung, S. [Department of Physics, University of Hong Kong (Hong Kong)

2008-10-06

116

Tensile Behavior of Al2o3/feal + B and Al2o3/fecraly Composites  

NASA Technical Reports Server (NTRS)

The feasibility of Al2O3/FeAl + B and Al2O3/FeCrAlY composites for high-temperature applications was assessed. The major emphasis was on tensile behavior of both the monolithics and composites from 298 to 1100 K. However, the study also included determining the chemical compatibility of the composites, measuring the interfacial shear strengths, and investigating the effect of processing on the strength of the single-crystal Al2O3 fibers. The interfacial shear strengths were low for Al203/FeAl + B and moderate to high for Al203/FeCrAlY. The difference in interfacial bond strengths between the two systems affected the tensile behavior of the composites. The strength of the Al203 fiber was significantly degraded after composite processing for both composite systems and resulted in poor composite tensile properties. The ultimate tensile strength (UTS) values of the composites could generally be predicted with either rule of mixtures (ROM) calculations or existing models when using the strength of the etched-out fiber. The Al2O3/FeAl + B composite system was determined to be unfeasible due to poor interfacial shear strengths and a large mismatch in coefficient of thermal expansion (CTE). Development of the Al2O3/FeCrAlY system would require an effective diffusion barrier to minimize the fiber strength degradation during processing and elevated temperature service.

Draper, S. L.; Eldridge, J. I.; Aiken, B. J. M.

1995-01-01

117

Teatro al Sur y la escena Argentina  

E-print Network

140 LATIN AMERICAN THEATRE REVIEW Teatro al Sur y la escena Argentina Acaba de aparecer un nuevo número de Teatro al Sur, Revista Latinoamericana. Su título de tapa - Teatro Argentino a varias voces - resume la intención de esta nueva entrega... publicación: nos pareció oportuno apelar al testimonio directo de algunos de nuestros creadores y a través de sus voces - con particulares texturas y coloraturas - ir configurando un fragmento significativo del presente de nuestra escena. Hemos preferido...

2000-04-01

118

Mangan-Nickel-und Cobaltverbindungen als Konversionselektrodenmaterialien  

E-print Network

Mangan- Nickel- und Cobaltverbindungen als Konversionselektrodenmaterialien für Lithium ____________________________________________________63 5.1 SYNTHESE UND CHARAKTERISIERUNG VON NANOSKALIGEM LIF ______________________________63 5

Hoffmann, Rolf

119

Superbend era begins swiftly at the ALS  

SciTech Connect

The successful installation and commissioning of high-field superconducting bend magnets (superbends) in three curved sectors of ALS storage ring was the first time the magnet lattice of an operating synchrotron light source has been retrofitted in this fundamental way. As a result, the ALS now offers an expanded spectral range well into the hard x-ray region without compromising either the number of undulators or their high brightness in the soft x-ray region for which the ALS design was originally optimized. In sum, when the superbend-enhanced ALS started up for user operations in October 2001, it marked the beginning of a new era in its history.

Robinson, Art; Tamura, Lori

2001-11-29

120

Microstructures and wear resistances of hybrid Al–(Al 3Ti+Al 3Ni) FGMs fabricated by a centrifugal method  

Microsoft Academic Search

The Al based functionally graded materials (FGMs), reinforced by a hybrid of Al3Ti platelets and Al3Ni granular particles, were fabricated by the centrifugal method with both ingots of commercial Al–5mass%Ti and Al–20mass%Ni master alloys. The ratios of Al–Ti and Al–Ni alloys were 3:1, 1:1 and 1:3 (in mass), and the applied G numbers are 30, 50 and 80. The microstructures

Yoshimi Watanabe; Tatsuru Nakamura

2001-01-01

121

Toxicity of Al to Desulfovibrio desulfuricans  

PubMed Central

The toxicity of Al to Desulfovibrio desulfuricans G20 was assessed over a period of 8 weeks in a modified lactate C medium buffered at four initial pHs (5.0, 6.5, 7.2, and 8.3) and treated with five levels of added Al (0, 0.01, 0.1, 1.0, and 10 mM). At pH 5, cell population densities decreased significantly and any effect of Al was negligible compared to that of the pH. At pHs 6.5 and 7.2, the cell population densities increased by 30-fold during the first few days and then remained stable for soluble-Al concentrations of <5 × 10?5 M. In treatments having total-Al concentrations of ?1 mM, soluble-Al concentrations exceeded 5 × 10?5 M and limited cell population growth substantially and proportionally. At pH 8.3, soluble-Al concentrations were below the 5 × 10?5 M toxicity threshold and cell population density increases of 20- to 40-fold were observed. An apparent cell population response to added Al at pH 8.3 was attributed to the presence of large, spirilloidal bacteria (accounting for as much as 80% of the cells at the 10 mM added Al level). Calculations of soluble-Al speciation for the pH 6.5 and 7.2 treatments that showed Al toxicity suggested the possible presence of the Al13O4(OH)24(H2O)127+ “tridecamer” cation and an inverse correlation of the tridecamer concentration and the cell population density. Analysis by 27Al nuclear magnetic resonance spectroscopy, however, yielded no evidence of this species in freshly prepared samples or those taken 800 days after inoculation. Exclusion of the tridecamer species from the aqueous speciation calculations at pHs 6.5 and 7.2 yielded inverse correlations of the neutral Al(OH)3 and anionic Al(OH)4? monomeric species with cell population density, suggesting that one or both of these ions bear primary responsibility for the toxicity observed. PMID:12839782

Amonette, J. E.; Russell, C. K.; Carosino, K. A.; Robinson, N. L.; Ho, J. T.

2003-01-01

122

Thermal expansion of gehlenite, Ca2Al[AlSiO7], and the related aluminates LnCaAl[Al2O7] with Ln = Tb, Sm  

NASA Astrophysics Data System (ADS)

The thermal expansion of gehlenite, Ca2Al[AlSiO7], (up to T=830 K), TbCaAl[Al2O7] (up to T=1100 K) and SmCaAl[Al2O7] (up to T=1024 K) has been determined. All compounds are of the melilite structure type with space group P{bar{4}}21m. Thermal expansion data were obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg (Germany). The thermal expansion coefficients for gehlenite were found to be: ?1=7.2(4)×10-6×K-1+3.6(7)×10-9? T×K-2 and ?3=15.0(1)×10-6×K-1. For TbCaAl[Al2O7] the respective values are: ?1=7.0(2)×10-6×K-1+2.0(2)×10-9? T×K-2 and ?3=8.5(2)×10-6×K-1+2.0(3)×10-9? T×K-2, and the thermal expansion coefficients for SmCaAl[Al2O7] are: ?1=6.9(2)×10-6×K-1+1.7(2)×10-9? T×K-2 and ?3=9.344(5)×10-6×K-1. The expansion mechanisms of the three compounds are explained in terms of structural trends obtained from Rietveld refinements of the crystal structures of the compounds against the powder diffraction patterns. No structural phase transitions have been observed. While gehlenite behaves like a ‘proper’ layer structure, the aluminates show increased framework structure behavior. This is most probably explained by stronger coulombic interactions between the tetrahedral conformation and the layer-bridging cations due to the coupled substitution (Ca2++Si4+) ( Ln 3++Al3+) in the melilite-type structure.

Peters, L.; Knorr, K.; Knapp, M.; Depmeier, W.

2005-12-01

123

Preparation and Thermoelectric Properties of YbAl3 Thermoelectric Materials with Excessive Al  

NASA Astrophysics Data System (ADS)

A method to prepare YbAl3 sample with an accurate stoichiometric ratio has been developed by a melting, quenching, annealing and spark plasma sintering (SPS) method. A series of YbAl3 thermoelectric materials with nominal compositions YbAl3+x (x = 0-0.3, ?x = 0.1) have been prepared using the method. We have explored the effects of the excessive Al on phase compositions, microstructure and transport properties. The quenched samples are composed of YbAl3, YbAl2, Yb, and Al. All the annealed samples are composed of main phase YbAl3 and a trace of Al; some annealed samples with x = 0 and x = 0.1 still contain a trace of YbAl2. The SPSed samples with x ? 0.1 are composed of single-phase YbAl3, though a trace of YbAl2 still occured in the SPSed sample with x = 0. The electrical conductivity, Seebeck coefficient, power factor, thermal conductivity and ZT values are first increased with increasing x in the range of 0-0.2 and then decreased when x > 0.2. These thermoelectric properties evolutions originate from the change of densities and chemical composition induced by the excessive Al. The highest ZT value reaches 0.28 at 300 K for the SPSed sample with x = 0.2.

He, Dan-qi; Zhao, Wen-Yu; Mu, Xin; Zhou, Hong-yu; Zhang, Qing-jie

2015-01-01

124

SCIENCE CAREER Al nanoclusters in coagulants and granulates: application  

E-print Network

aluminum hydroxide complexes with 1 nm diameter and 1­2 nm length. Al13 is a cluster of four Al trimers suitable for arsenic removal. The aluminum nanocl- usters Al13 (AlO4Al12(OH)24H2O12 7? ) and Al30 (Al2O8Al properties of aluminum nanoclusters and their efficiency for water treatment, particularly for arsenic

Wehrli, Bernhard

125

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

126

Freund et al. Mechanisms underlying differential expression  

E-print Network

Freund et al. - 1 - Mechanisms underlying differential expression of interleukin-8 in breast cancer cells Ariane Freund, Valérie Jolivel, Sébastien Durand, Nathalie Kersual, Dany Chalbos, Carine Chavey #12;Freund et al. - 2 - ABSTRACT We have recently reported that Interleukin-8 (IL-8) expression

Boyer, Edmond

127

Quantitatively Probing the Al Distribution in Zeolites  

SciTech Connect

The degree of substitution of Si4+ by Al3+ in the oxygen-terminated tetrahedra (Al T-sites) of zeolites determines the concentration of ion-exchange and Brønsted acid sites. As the location of the tetrahedra and the associated subtle variations in bond angles influence the acid strength, quantitative information about Al T-sites in the framework is critical to rationalize catalytic properties and to design new catalysts. A quantitative analysis is reported that uses a combination of extended X-ray absorption fine structure (EXAFS) analysis and 27Al MAS NMR spectroscopy supported by DFT-based molecular dynamics simulations. To discriminate individual Al atoms, sets of ab initio EXAFS spectra for various T-sites are generated from DFT-based molecular dynamics simulations allowing quantitative treatment of the EXAFS single- and multiple-photoelectron scattering processes out to 3-4 atom shells surrounding the Al absorption center. It is observed that identical zeolite types show dramatically different Al-distributions. A preference of Al for T-sites that are part of one or more 4-member rings in the framework over those T-sites that are part of only 5- and 6-member rings in the HBEA150 sample has been determined from a combination of these methods. This work was supported by the U. S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences.

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

2014-06-11

128

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, 2014

...Known as Uthman Ahmad Uthman al-Ghamdi, Also Known as Othman Ahmed Othman al-Omirah as a Specially Designated Global Terrorist Pursuant to Section 1(b) of Executive Order 13224, as Amended Acting under the authority of and in accordance with...

2011-06-20

129

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 and…

Jungerberg, Tom; Smith, Anna; Borsh, Colleen

2012-01-01

130

PROVE DI IMPATTO SU PANNELLI AL - NOMEX  

Microsoft Academic Search

Sommario Il presente lavoro descrive prove preliminari di impatto a bassa velocità effettuate su un pannello sandwich (Al-Nomex) utilizzato estesamente su fusoliere di elicottero. Non essendoci una normativa vigente sull'intero processo di prova, è stato eseguito un ampio studio preliminare al fine di valutare le possibili soluzioni utilizzabili. E' stata quindi realizzata una struttura di prova dedicata composta da una

M. Giglio; A. Manes

131

Durability Assessment of TiAl Alloys  

NASA Technical Reports Server (NTRS)

The durability of TiAl is a prime concern for the implementation of TiAl into aerospace engines. Two durability issues, the effect of high temperature exposure on mechanical properties and impact resistance, have been investigated and the results are summarized in this paper. Exposure to elevated temperatures has been shown to be detrimental to the room temperature ductility of gamma alloys with the most likely mechanisms being the ingress of interstitials from the surface. Fluorine ion implantation has been shown to improve the oxidation resistance of gamma alloys, and ideally it could also improve the environmental embrittlement of high Nb content TiAl alloys. The effect of F ion implantation on the surface oxidation and embrittlement of a third generation, high Nb content TiAl alloy (Ti-45Al-5Nb-B-C) were investigated. Additionally, the ballistic impact resistance of a variety of gamma alloys, including Ti-48Al-2Cr- 2Nb, Ti-47Al-2Cr-2Nb, ABB-2, ABB-23, NCG359E, 95A and Ti-45Al-5Nb-B-C was accessed. Differences in the ballistic impact properties of the various alloys will be discussed, particularly with respect to their manufacturing process, microstructure, and tensile properties.

Draper, Susan L.; Lerch, Bradley A.

2008-01-01

132

Energetics of Al13 Keggin cluster compounds  

PubMed Central

The ?-Al13 Keggin aluminum hydroxide clusters are essential models in establishing molecular pathways for geochemical reactions. Enthalpies of formation are reported for two salts of aluminum centered ?-Keggin clusters, Al13 selenate, (Na(AlO4)Al12(OH)24(SeO4)4•12H2O) and Al13 sulfate, (NaAlO4Al12(OH)24(SO4)4•12H2O). The measured enthalpies of solution, ?Hsol, at 28?°C in 5 N HCl for the ?-Al13 selenate and sulfate are ?924.57 (± 3.83) and ?944.30 ( ± 5.66) kJ·mol-1, respectively. The enthalpies of formation from the elements, ?Hf,el, for Al13 selenate and sulfate are ?19,656.35 ( ± 67.30) kJ·mol-1, and ?20,892.39 ( ± 70.01) kJ·mol-1, respectively. In addition, ?Hf,el for sodium selenate decahydrate was calculated using data from high temperature oxide melt solution calorimetry measurements: ?4,006.39 ( ± 11.91) kJ·mol-1. The formation of both ?-Al13 Keggin cluster compounds is exothermic from oxide-based components but energetically unfavorable with respect to a gibbsite-based assemblage. To understand the relative affinity of the ?-Keggin clusters for selenate and sulfate, the enthalpy associated with two S-Se exchange reactions was calculated. In the solid state, selenium is favored in the Al13 compound relative to the binary chalcogenate, while in 5 N HCl, sulfur is energetically favored in the cluster compound compared to the aqueous solution. This contribution represents the first thermodynamic study of ?-Al13 cluster compounds and establishes a method for other such molecules, including the substituted versions that have been created for kinetic studies. Underscoring the importance of ?-Al13 clusters in natural and anthropogenic systems, these data provide conclusive thermodynamic evidence that the Al13 Keggin cluster is a crucial intermediate species in the formation pathway from aqueous aluminum monomers to aluminum hydroxide precipitates. PMID:21852572

Armstrong, Christopher R.; Casey, William H.; Navrotsky, Alexandra

2011-01-01

133

NiAl alloys for structural uses  

NASA Technical Reports Server (NTRS)

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

Koss, D. A.

1991-01-01

134

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

135

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

136

Dry sliding wear of Al alloy 2024Al 20 3 particle metal matrix composites  

Microsoft Academic Search

In the present investigation, Al 2024-15vol.%Al203 particulate (average size, 18 ?m) composites were fabricated using the liquid metallurgy route. The wear and friction characteristics of AI alloy 2024 and Al 2024-15vol.%Al203p composite in the as-extruded and peak-aged conditions were studied using a pin-on-disc machine (with a steel disc as the counterface material). The worn surfaces, subsurfaces and the debris were

Manish Narayan; M. K. Surappa; B. N. Pramila Bai

1995-01-01

137

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

E-print Network

Site preferences of indium impurity atoms in intermetallics having Al3Ti and Al3Zr crystal · Indium was doped in samples of Al3V and Al3Ti (Al3Ti structure) and Al3Zr (Al3Zr structure) by arc-melting; doping at 10 ppb level. · Inequivalent Al-sites occupied by indium solutes were identified by measuring

Collins, Gary S.

138

IDENTIFIKASI PENGENDALIAN APLIKASI DALAM ANALISIS PROSES BISNIS  

Microsoft Academic Search

usiness process analysis has been found in many literatures as a mean of a well developed accounting information system. Application control exists as one of its core component. This paper investigates the business process analysis to understand application control better by embracing combination of COSO and COBIT control frameworks. Case study was conducted in a Singapore-based small furniture trading company.

Hamzah Ritchi

139

Caratterizzazioni per il territorio Analisi dendrocronologiche  

E-print Network

.armanini@unitn.it. · Modellazione ciclo idrologico Dipartimento di Ingegneria Civile e Ambientale, Laboratorio Idraulica, prof.frattari@unitn.it. · Rilevamenti in campo Dipartimento di Ingegneria Civile e Ambientale, Laboratorio Dendrocronologia Forestale Dipartimento di Ingegneria Civile e Ambientale, Laboratorio GIS, prof. Benciolini. Tel. 0461 282632, e

140

ANALISI DINAMICA NUMERICA COMPARATA DI MOTOCICLI  

Microsoft Academic Search

This study is aimed to define the dynamic behaviour in the symmetry plane of motorcycles having different kind of suspensions. The four models involved in the virtual dynamic tests were chosen according to the following specifications: a model called RY Griffon was realised with a deformable quadrilateral device, for the front suspension and a controlled deflection cantilever rear suspension. The

C. Bruschi; S. Papalini; A. Ranalli

141

Reassessment of Al-Ce and Al-Nd Binary Systems Supported by Critical Experiments and First-Principles  

E-print Network

Reassessment of Al-Ce and Al-Nd Binary Systems Supported by Critical Experiments and First The present study reinvestigates the Al-Ce and Al-Nd phase diagrams and reoptimizes their thermody- namics results and theoretical calculations show that Al2Nd (or Al2Ce) should be treated as a stoichiometric

Widom, Michael

142

Atomistic Modeling of RuAl and (RuNi) Al Alloys  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

143

High Al-content AlGaN\\/GaN MODFETs for ultrahigh performance  

Microsoft Academic Search

The use of an AlGaN layer with high Al mole-fraction is proposed to increase the equivalent figures of merit of the AlGaN\\/GaN MODFET structure. It is shown that the room temperature mobility has little degradation with increasing Al mole-fraction up to 50%. 0.7-?m gate-length Al0.5Ga0.5N\\/GaN MODFETs by optical lithography exhibit a current density of 1 A\\/mm and three-terminal breakdown voltages

Y.-F. Wu; B. P. Keller; P. Fini; S. Keller; T. J. Jenkins; L. T. Kehias; S. P. Denbaars; U. K. Mishra

1998-01-01

144

AlGaN/GaN/AlN quantum-well field-effect transistors with highly resistive AlN epilayers  

E-print Network

of the AlGaN/GaN/AlN QW-FET structure used in this study. A Si -doping level of 4.5 10AlGaN/GaN/AlN quantum-well field-effect transistors with highly resistive AlN epilayers Z. Y. Fana 66506-2601 Received 23 November 2005; accepted 5 January 2006; published online 16 February 2006 AlGaN/GaN

Jiang, Hongxing

145

Single-phase interdiffusion in the B2 type intermetallic compounds NiAl, CoAl and FeAl  

Microsoft Academic Search

Interdiffusion coefficients, D, in the B2 type NiAl, CoAl and FeAl phases have been determined by single phase diffusion couples over a wide temperature range from 1073 to 1773 K. The value of D in the NiAl and CoAl phases shows a minimum at about 47 at.% Al deviating slightly from the stoichiometric composition, while the value of D in

Ryusuke Nakamura; Koichi Takasawa; Yoshihiro Yamazaki; Yoshiaki Iijima

2002-01-01

146

Solar-blind ultraviolet AlInN/AlGaN distributed Bragg reflectors  

NASA Astrophysics Data System (ADS)

A 13.5-pair Al0.98In0.02N/Al0.77Ga0.23N distributed Bragg reflector (DBR) was grown by molecular beam epitaxy on an AlN template substrate. The DBR exhibited a peak reflectivity of 83.9% at 246 nm within the deep solar-blind ultraviolet region and a stopband width of 18 nm. The average refractive index contrast for the DBR was 9.25% at 246 nm, which is relatively high compared with that of a traditional Al(Ga)N/(Al)GaN DBR. Simulated results indicated that a 25.5-pair Al0.98In0.02N/Al0.77Ga0.23N DBR will provide a reflectivity higher than 99% and a 19 nm wide stopband with a center wavelength of 246 nm.

Zhang, Lili; Dong, Kexiu; Chen, Dunjun; Liu, Yanli; Xue, Junjun; Lu, Hai; Zhang, Rong; Zheng, Youdou

2013-06-01

147

Optical characterization of Al- and N-polar AlN waveguides for integrated optics  

NASA Astrophysics Data System (ADS)

Dispersion of the extraordinary and ordinary refractive indices of Al- and N-polar AlN waveguides is measured by multiple angle-of-incidence and spectroscopic ellipsometry techniques. The polarity-controlled AlN layers are grown by metal–organic chemical vapor deposition on (0001)-sapphire substrates. Taking into consideration the different surface morphologies of the Al- and N-polar AlN waveguides, we propose two optical models to describe the measured ellipsometry data. The results indicate that there is no difference between the refractive indices of the AlN grown in opposite directions, which confirms the potential of the AlN lateral polar structures for use in nonlinear optical applications based on quasi phase matching.

Rigler, Martin; Buh, Jože; Hoffmann, Marc P.; Kirste, Ronny; Bobea, Milena; Mita, Seiji; Gerhold, Michael D.; Collazo, Ramon; Sitar, Zlatko; Zgonik, Marko

2015-04-01

148

High quality AlGaN grown on ELO AlN/sapphire templates  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

149

Spin reorientation in Al/Metglas 2605S2/Al trilayers induced by magnetoelastic effect  

NASA Astrophysics Data System (ADS)

Mössbauer spectroscopy, in a broad temperature interval of 12-425 K, has been applied to investigate the spin reorientation dynamics caused by the temperature induced magnetoelastic effect on Al(x ?m)/Metglas 2605S2 (20 ?m)/Al(x ?m) trilayers (x =0; 2.5; 5 and 20). It was found that the angle between the average sample magnetization and gamma ray direction (perpendicular to the sample plane) depends on the Al layer thickness. For temperatures smaller than 260 K, saturation of spin reorientation, which can be controlled by adjusting the Al thickness, was reached for Al thicknesses larger than and equal to 5 ?m. For a 20 ?m Al thickness, changes in the F57e atom spin and charge densities have also been observed. A simple spin model has been proposed to describe qualitatively the spin reorientation effect as well as the influence of the Al thickness on the spin reorientation sensitivity.

Moscon, P. S.; Passamani, E. C.; Larica, C.; Takeuchi, A. Y.; Sánchez, F. H.; Zélis, P. Mendoza; Baggio-Saitovitch, Elisa

2008-09-01

150

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

151

Crack-free thick AlGaN grown on sapphire using AlN/AlGaN superlattices for strain management  

NASA Astrophysics Data System (ADS)

We report on an AlN/AlGaN superlattice approach to grow high-Al-content thick n+-AlGaN layers over c-plane sapphire substrates. Insertion of a set of AlN/AlGaN superlattices is shown to significantly reduce the biaxial tensile strain, thereby resulting in 3-?m-thick, crack-free Al0.2Ga0.8N layers. These high-quality, low-sheet-resistive layers are of key importance to avoid current crowding in quaternary AlInGaN multiple-quantum-well deep-ultraviolet light-emitting diodes over sapphire substrates.

Zhang, J. P.; Wang, H. M.; Gaevski, M. E.; Chen, C. Q.; Fareed, Q.; Yang, J. W.; Simin, G.; Khan, M. Asif

2002-05-01

152

Glial cells in ALS: the missing link?  

PubMed

Amyotrophic lateral sclerosis (ALS) was initially known as Charcot's sclerosis, named after the French neurobiologist and physician Jean-Martin Charcot who first described this type of muscular atrophy in the early nineteenth century. In the United States, ALS became widely known as Lou Gehrig's disease after the famous baseball player who succumbed to the disease in the late 1930s. Currently, ALS is the most common motor neuron disease, with a worldwide incidence of 8 cases per 100,000 population per year. Familial forms constitute approximately 5% to 10% of all cases. Onset increases with age, with a peak in the seventh decade and a slight preponderance (relative risk, 1.3-1.5) among men compared with women. Rapid progression of motor neuron loss leads to death an average of 3 to 5 years after symptom onset. The cause of ALS remains unknown and there is still no curative therapy. PMID:18625409

Raibon, Elsa; Todd, Lisa Marie; Möller, Thomas

2008-08-01

153

US 20080226134Al (19) United States  

E-print Network

Classi?cation CONTROLLER (51) Int- Cl (76) Inventors: George DeWitt STETTEN,Pittsburgh, PA (US); Roberta/0226134 A1 STETTEN et al. (43) Pub. Date: Sep. 18, 2008 (54) FINGERTIP VISUAL HAPTIC SENSOR Publication

Stetten, George

154

Everyday Life with ALS: A Practical Guide  

MedlinePLUS

... years ago. ALS: Maintaining Mobility, A Guide to Physical Therapy and Occupational Therapy proved to be an invaluable ... several approaches to communication in ways other than traditional speech. Weakness can limit your ability to accomplish ...

155

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

156

Half life of /sup 26/Al  

SciTech Connect

The half-life of /sup 26/Al has been redetermined because of suggestions of an error in the accepted value based on its use in calculating /sup 21/Ne production rates from cosmic rays in meteorites. Two solutions of /sup 26/Al were analyzed for the specific radioactivity and mass spectrometric determination of the /sup 26/Al concentration. The half-life obtained for /sup 26/Al was 7.05 x 10/sup 5/ years +- 3.7% at the two sigma level. This is identical to the accepted value of 7.16 x 10/sup 5/ years and indicates that problems with the /sup 21/Ne production rate is not due to an erroneous half-life.

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

1983-01-01

157

Innovative Al Damascene Process for Nanoscale Interconnects  

Microsoft Academic Search

A novel chemical vapor deposition (CVD)-Al technique of ``bottom-up growth'' was developed using methylpyrrolidine alane as a precursor and a (PVD)-TiN\\/CVD-TiN stacked barrier in a damascene structure. Poor step coverage of PVD-TiN caused an absence of PVD-TiN at the bottom of trenches, resulting in selective Al growth. The new method filled a 40-nm-wide trench (aspect ratio = 7.5) completely and

Kyung-In Choi; Sung-Ho Han; Sera Yun; Dae-Yong Kim; Jong Won Hong; Sang Woo Lee; Byung Hee Kim; Sung-Tae Kim; U-In Chung; Joo-Tae Moon; Byung-Il Ryu

2006-01-01

158

Magnetism of Al-Mn quasicrystals  

SciTech Connect

The effect of symmetry and concentration of Mn on the magnetism of Al-Mn quasicrystals has been investigated through self-consistent density-functional calculations using molecular clusters and supercell band-structure schemes. A single Mn atom surrounded by 54 Al atoms in an icosahedral or a cuboctahedral structure is found to be nonmagnetic. However, as the Mn concentration is increased, moments develop on Mn sites whose magnitude and coupling depend on their location.

Liu, F.; Khanna, S.N.; Magaud, L.; Jena, P. (Physics Department, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)); de Coulon, V.; Reuse, F. (Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, PHB-Ecublens, Lausanne (Switzerland)); Jaswal, S.S.; He, X. (Department of Physics and Astronomy, The University of Nebraska-Lincoln, 260 Behlen Laboratory, Lincoln, Nebraska 68588-0111 (United States)); Cyrot-Lackman, F. (Laboratoire d'Etudes des Proprietes Electroniques des Solides, Centre National de la Recherche Scientifique, Boite Postale 166X, 38042 Grenoble, CEDEX France ( ))

1993-07-01

159

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

160

Continuous germanene layer on al(111).  

PubMed

Germanene, a 2D honeycomb structure similar to silicene, has been fabricated on Al(111). The 2D germanene layer covers uniformly the substrate with a large coherence over the Al(111) surface atomic plane. It is characterized by a (3 × 3) superstructure with respect to the substrate lattice, shown by low energy electron diffraction and scanning tunnelling microscopy. First-principles calculations indicate that the Ge atoms accommodate in a very regular atomic configuration with a buckled conformation. PMID:25802988

Derivaz, Mickael; Dentel, Didier; Stephan, Régis; Hanf, Marie-Christine; Mehdaoui, Ahmed; Sonnet, Philippe; Pirri, Carmelo

2015-04-01

161

Structure of decagonal Al-Ni-Rh.  

PubMed

The crystal structure of the decagonal phase in the system Al-Ni-Rh (d-Al-Ni-Rh) was analyzed in the five-dimensional embedding approach based on single-crystal synchrotron X-ray diffraction data. The structure can be described as a quasiperiodic packing of partially overlapping decagonal and pentagonal columnar clusters with ??21?Å diameter and ??4?Å period along the tenfold axis. PMID:25080252

Logvinovich, Dmitry; Simonov, Arkadiy; Steurer, Walter

2014-08-01

162

Effects of Al on nitrogen (NH  

Microsoft Academic Search

After growth for 17 to 36 days on nutrient solutions with NH4NO3 as nitrogen source (pH 4.2) dry matter of sorghum genotype SC0283 was much less affected by Al (1.5 and 3.0 ppm) than that\\u000a of genotype NB9040.\\u000a \\u000a In the absence of Al both cultivars released protons into the nutrient solution as a result of an excess of cationic nutrients

W. G. Keltjens; P. S. R. van Ulden

1987-01-01

163

Interband optical properties of Ni3Al  

Microsoft Academic Search

We present calculations of interband optical conductivity of the compound Ni3Al using the linear-muffin-tin-orbital method. Calculations are performed using constant matrix elements and calculated matrix elements. We find that matrix elements play a significant role in influencing the magnitude of optical conductivity sigma(omega) and the position of peaks. Since Ni3Al is weakly ferromagnetic (magnetic moment equal to 0.31muB per unit

M. A. Khan; Arti Kashyap; A. K. Solanki; T. Nautiyal; S. Auluck

1993-01-01

164

Magnetic Properties of Disordered Fe3Al  

NASA Astrophysics Data System (ADS)

The magnetic properties of Fe3Al powders prepared by filing the ingot in both as-filed and annealed form are studied. Results of Mössbauer, X-ray diffraction and DC magnetization studies show that the magnetic properties are modified due to formation of non-magnetic Fe3AlC0.5 phase due to C intercalated on filing. The hyperfine fields obtained are explained in terms of nearest and next nearest neighbor configurations of 57Fe.

Nehra, J.; Kabra, K.; Jani, S.; Ranjith, P. M.; Lakshmi, N.; Venugopalan, K.

2011-07-01

165

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

166

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

167

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. PMID:21515558

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

168

OVERVIEW NO. 136 DIFFUSION IN THE TiAl SYSTEM  

E-print Network

. Keywords: Intermetallic compounds; Diusion; Radio-tracer method; Theory and modeling 1. INTRODUCTION Intermetallic compounds of the Ti±Al system and alloys based on such compounds are materials of rapidly growing in a-Ti(Al), b-Ti(Al), and intermetallic phases a2-Ti3Al and g-TiAl, are summarized. The results

Mishin, Yuri

169

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

NASA Astrophysics Data System (ADS)

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

Hickmott, T. W.

2013-12-01

170

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

Federal Register 2010, 2011, 2012, 2013, 2014

...Front, Jabhat al-Nusrah, Jabhet al-Nusra, The Victory Front, Al Nusrah Front...aka Jabhat al-Nusrah, aka Jabhet al-Nusra, aka The Victory Front, aka Al...Front, Jabhat al-Nusrah, Jabhet al-Nusra, The Victory Front, Al Nusrah...

2012-12-11

171

Comment on ``A new interpretation of Weimer et al.'s solar wind propagation delay technique'' by Bargatze et al.  

NASA Astrophysics Data System (ADS)

In a recent article, Bargatze et al. (2005) have identified why the implementation of the minimum variance analysis (MVAB) by Weimer et al. (2003), even though based on an erroneous variance matrix, has been successful in estimating the orientation of the "phase fronts" and the resulting propagation delays of the interplanetary magnetic field (IMF). They recommend further testing of the Weimer analysis as a space weather forecasting tool. In this comment we stress that the Weimer et al. implementation of MVAB closely mimics the results of a well-known version of MVAB that is constrained by the condition that the average field along the phase front normals is zero. This version of MVAB starts from the correct variance matrix, whereas the Weimer analysis is based on an unphysical matrix resulting from a programming error. We recommend that the constrained MVAB, originally developed by Sonnerup and Cahill (1968) and later recast into a more convenient form by A.V. Khrabrov be used instead. The Khrabrov method, which we refer to as MVAB-0, has been tested at the Earth's magnetopause by Sonnerup and Scheible (1998) and more recently by Haaland et al. (2004) and Sonnerup et al. (2004).

Haaland, S.; Paschmann, G.; Sonnerup, B. U. Ã.-.

2006-06-01

172

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

173

Analog resistive switching behavior of Al/Nb2O5/Al device  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

174

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

PubMed Central

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

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

2011-01-01

175

Short-period superlattices of AlN/Al0.08Ga0.92N grown on AlN substrates S. A. Nikishin,a)  

E-print Network

energy electron diffraction (RHEED). The Al-face AlN substrates11 were nominally (0001) ori- ented and Nano Tech Center, Texas Tech University, Lubbock, Texas 79409-3102 M. Holtz Nano Tech Center-source molecular-beam epitaxy with ammonia on Al face of AlN (0001) substrates. A significant reduction

Holtz, Mark

176

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

177

Surface Superstructures of Ordered Layers of Al2O3 on Ni3Al(001)  

Microsoft Academic Search

Atomically ordered Al2O3 obtained by thermal oxidation of the Ni3Al(001) surface was studied using scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). LEED analysis has shown that oxidation at 800 and 1100 K forms two different structural phases of Al2O3. Detailed STM studies of both phases also reveal remarkable differences in surface pattern structure and arrangement of the domains.

Oleg Kurnosikov; Cees F. J. Flipse; Henk J. M. Swagten; Bert Koopmans; Wim J. M. de Jonge

2006-01-01

178

Comparing characteristics of serrations in Al–Li and Al–Mg alloys  

Microsoft Academic Search

Characteristics of serrations in the flow stress–strain curves of Al–1Mg and Al–2Li alloys, obtained from tensile tests, are analyzed and compared. The analysis includes stress drop, drop time and reload time at various ageing durations of the alloys. Changes in distributions of the stress drops and the drop time with changing the ageing duration differ markedly in Al–2Li from those

Baohui Tian

2003-01-01

179

Molecular beam epitaxial regrowth on insitu plasma-etched AlAs\\/AlGaAs heterostructures  

Microsoft Academic Search

Epitaxial regrowth by solid-source molecular beam epitaxy (MBE) on dry etched heterostructures possessing exposed AlAs surfaces is accomplished for the first time using a vacuum integrated processing. Samples composed of multilayers of AlAs and AlGaAs are patterned with a SiO2 mask and are anisotropically etched using a low damage electron cyclotron resonance (ECR) SiCl4 plasma process. Etched samples are transferred

Kent D. Choquette; M. Hong; R. S. Freund; S. N. G. Chu; J. P. Mannaerts; R. C. Wetzel; R. E. Leibenguth

1992-01-01

180

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

181

Structure of 26Al studied by one - nucleon transfer reaction 27Al(d,t)  

NASA Astrophysics Data System (ADS)

The excited states of 26Al have been produced and studied using 27Al(d,t) reaction with 25 MeV deuteron as projectile. Optical model potential parameters were extracted from the measured elastic scattering angular distribution. Zero range distorted wave Born approximation analysis for the ground and 0.223 MeV states of 26Al have been done. The spectroscopic factors calculated for these states are found to be in good agreement with the previously reported values.

Srivastava, Vishal; Bhattacharya, C.; Rana, T. K.; Manna, S.; Kundu, S.; Bhattacharya, S.; Banerjee, K.; Roy, P.; Pandey, R.; Mukherjee, G.; Ghosh, T. K.; Meena, J. K.; Roy, T.; Chaudhuri, A.; Sinha, M.; Saha, A.; Dey, A.; Asgar, Md. A.; Roy, Subinit; Shaikh, Md. M.

2015-01-01

182

Remarks on Peinado et al.'s Analysis of J3Gen.  

PubMed

Peinado et al. analyzed the security of the J3Gen pseudorandom number generator proposed by Melià-Seguí et al., and claimed weaknesses regarding its security properties. They also presented a deterministic attack based on the decimation of the J3Gen output sequences. We show that the assumptions made by Peinado et al. are not correct and that the proposed deterministic attack against J3Gen does not hold in practice. PMID:25781510

Garcia-Alfaro, Joaquin; Herrera-Joancomartí, Jordi; Melià-Seguí, Joan

2015-01-01

183

Thermodynamic properties of alloys of the Al-Co and Al-Co-Sc systems  

NASA Astrophysics Data System (ADS)

Enthalpies of mixing for melts of the binary Al-Co system at 1870 K in the range 0 < x Co < 0.25, and at 1620 K, 0 < x Co < 0.12, are investigated by means of isoperibolic calorimetry. Enthalpies of mixing for melts of the ternary Al-Co-Sc system are investigated at 1870 K for sections Al0.75(1 - x)Co0.25(1 - x)Sc x , 0 < x < 0.024, and Al0.88(1 - x)Co0.12(1 - x)Sc x , 0 < x < 0.044. Using the literature data on the enthalpies of mixing for liquid and solid alloys, the activities of melt components, and the phase diagram of the Al-Co system, the thermodynamic properties of liquid and solid alloys of the Al-Co system over a wide range of temperatures and compositions are calculated using a software package of our own design, based on the model of ideal associated solutions (IAS). The enthalpies of mixing and the liquidus surface of the phase diagram of the ternary Al-Co-Sc system over the interval of concentrations are estimated by modeling with data on binary boundary subsystems. All of the components of both the binary Al-Co and ternary Al-Co-Sc systems tend to interact with one another quite strongly: ? H min(Al-Co) = -32.5 kJ/mol at x Co = 0.44; ? H min(Al-Co-Sc) = -46 kJ/mol for Al0.4Co0.3Sc0.3 (estimated).

Shevchenko, M. A.; Berezutskii, V. V.; Ivanov, M. I.; Kudin, V. G.; Sudavtsova, V. S.

2014-05-01

184

The lowest ionization potentials of Al2  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

185

77 FR 40492 - Revocation of Class D Airspace; Andalusia, AL; and Amendment of Class E Airspace; Fort Rucker, AL  

Federal Register 2010, 2011, 2012, 2013, 2014

...also updates the geographic coordinates of the above airport; Cairns AAF, Ft. Rucker, AL; and Florala Municipal, AL, to be...ASO AL E5 Fort Rucker, AL [Amended] Fort Rucker, Cairns AAF, AL (Lat. 31[deg]16'33'' N., long....

2012-07-10

186

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

1998-05-01

187

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

PubMed Central

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

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

1997-01-01

188

High temperature deformation of NiAl and CoAl  

NASA Technical Reports Server (NTRS)

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

Nix, W. D.

1982-01-01

189

Achieving conductive high Al-content AlGaN alloys for deep UV photonics  

NASA Astrophysics Data System (ADS)

Recent progresses in epitaxial growth and fundamental studies on electrical and optical properties of high Al-content AlGaN alloys with Si, Mg, and Zn doping are presented. For Si doped Al xGa1- xN, the Si activation energy was determined for x = 0 up to 1, and the resistivity of n-Al xGa1- xN was found to increases by one order of magnitude when Al content is increased by ~ 8%. From photoluminescence (PL) studies, three groups of deep impurity transitions were observed, related with deep level acceptors involving cation vacancy and its complexes: (VIII) 3-, (VIII-complex)2, and (VIII-complex) 1-, which are electron traps and compensating centers. By optimizing the growth processes to reduce the densities of cation vacancy and its complexes, the n-type conductivity of Al xGa1- xN was significantly improved. A record low room temperature n-type resistivity of 0.0075 ?•cm has been obtained for Al 0.7Ga 0.3N, and n-type conduction in pure AlN has also been achieved. We also review the electrical and optical measurement results of Mgdoped AlGaN and AlN. It was found that the overall material quality and conductivity of Mg-doped AlN are strongly correlated with the PL emission intensity of the nitrogen vacancy (V N 3+) related transition. Improved conductivity was obtained by suppressing the V N 3+ related emission line, which was attributed to the reduced hole compensation by V N 3+. With the identification of the emission peaks associated with V N 3+ hole compensating centers, the p-type conductivity of high Al-content AlGaN alloys was improved by monitoring and suppressing the intensity of the V N 3+ related emission lines. P-type conduction in Al xGa1- xN (x > 0.7) was confirmed at elevated temperatures (> 700 K). The possibility of using Zn as an alternative p-type dopant was also studied. It was found that contrary to the calculation, the energy level of Zn acceptor in AlN was about 0.74 eV, which is 0.23 eV deeper than Mg level in AlN.

Fan, Z. Y.; Lin, J. Y.; Jiang, H. X.

2007-02-01

190

Photoemission from Al Alloys during Tensile Deformation  

NASA Astrophysics Data System (ADS)

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

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

2004-03-01

191

Mg-doped Al-rich AlGaN alloys for deep UV emitters  

NASA Astrophysics Data System (ADS)

Mg doped Al-rich AlGaN epilayers with Al content as high as 0.7 is needed for obtaining deep UV LEDs with wavelengths shorter than 300 nm. This is one of the most crucial layers in deep UV LEDs and plays an important role for electron blocking and affects the hole injection into the active layer. Not only is this layer critical for the efficiency of deep UV LEDs, it could also introduce long wavelength emission components in UV LEDs. However, it is difficult to obtain high quality Mg doped Al-rich AlGaN epilayers and the resistivity of the grown films is usually extremely high. We report here on the growth, optical and electrical properties of Mg doped Al0.7Ga0.3N epilayers. Mg doped Al0.7Ga0.3N epilayers of high crystalline and optical qualities have been achieved after optimizing MOCVD growth conditions. Moreover, we have obtained a resistivity around 12,000 ? cm (near the theoretical limit with Mg doping) at room temperature and confirmed p-type conduction at elevated temperatures for optimized Mg-doped Al0.7Ga0.3N epilayers. The growth conditions of the optimized epilayer have been incorporated into deep UV LEDs with wavelength shorter than 300 nm. A significant enhancement in power output with a reduction in forward voltage, Vf, was obtained by employing this optimized Mg doped Al0.7Ga0.3N epilayer as an electron blocking layer. The long wavelength emission components in deep UV LEDs were also significantly suppressed. The fundamental limit for achieving p-type Al-rich AlGaN alloys is also discussed.

Nakarmi, Mim L.; Kim, Kyoung Hoon; Zhu, Kai; Lin, Jing Yu; Jiang, Hong Xing

2004-10-01

192

ALS and Frontotemporal Dysfunction: A Review  

PubMed Central

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

Achi, Eugene Y.; Rudnicki, Stacy A.

2012-01-01

193

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

194

[Al-Biruni--a universal scientist].  

PubMed

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

Kujundzi?, E; Masi?, I

1999-01-01

195

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

196

An Alternative Perspective on von Winterfeldt et al.'s (1997) Test of Consequence Monotonicity  

ERIC Educational Resources Information Center

D. von Winterfeldt, N.-K. Chung, R. D. Luce, and Y. Cho (see record 1997-03378-008) provided several tests for consequence monotonicity of choice or judgment, using certainty equivalents of gambles. The authors reaxiomatized consequence monotonicity in a probabilistic framework and reanalyzed von Winterfeldt et al.'s main experiment via a…

Ho, Moon-Ho R.; Regenwetter, Michel; Niederee, Reinhard; Heyer, Dieter

2005-01-01

197

A unique description of steady state deformation of Al and Al-Mg alloys  

Microsoft Academic Search

In this work, simple mathematical relations between the plastic strain rate, the flow stress and the temperature for steady state deformation of aluminium alloys are proposed. The expressions are based on the corresponding formula for pure Al considered as a reference material. A ‘master curve’ representing this relation for Al was obtained through a compilation of a large array of

G. Bermig; A. Bartels; H. Mecking; Y. Estrin

1997-01-01

198

Thermal behavior of Al and Al3 at. % Ge thin films on Si wafers  

Microsoft Academic Search

The mechanical stresses of a pure Al film and a low-thermal-expansion Al-3 at. % Ge thin film on (100) Si wafers are measured and compared in the temperature range of room temperature to 400 °C by the vibrating membrane method. The results are discussed including the comparison with those obtained by the popular wafer bending method. It was found that

B. S. Lim; W. C. Pritchet; K. P. Rodbell; K. N. Tu

1993-01-01

199

^27Al-NMR Study of the Spinel Compound CoAl2O4  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

200

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

201

Structures of AlN/VN superlattices with different AlN layer thicknesses  

E-print Network

, is characterized by high ionicity, short bond length, low compressibility, high thermal conductivity, and a wide B1-AlN, suggests that the phase transition is martensitic. II. EXPERIMENTAL PROCEDURES AlN/VN superlattices were grown on MgO(001) sub- strates in an ultrahigh vacuum dc-magnetron sputtering system that has

Marks, Laurence D.

202

Replication and Extension of Little et al.'s (2003) Forms and Functions of Aggression Measure  

ERIC Educational Resources Information Center

The goal of the current study was to replicate the confirmatory factor analysis of Little et al.'s (2003) aggression measure in an American sample of 69 children (mean age = 12.93 years; SD = 1.27). Although an exact replication of the original model could not be estimated given the small sample, a modified model representing a conceptual…

Fite, Paula J.; Stauffacher, Kirstin; Ostrov, Jamie M.; Colder, Craig R.

2008-01-01

203

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

204

University of AlAskA AnchorAge AlAskA Justice Forum  

E-print Network

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

Pantaleone, Jim

205

University of AlAskA AnchorAge AlAskA Justice Forum  

E-print Network

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

Pantaleone, Jim

206

AlAskA Justice Forum University of AlAskA AnchorAge  

E-print Network

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

Pantaleone, Jim

207

Directional Solidification and Mechanical Properties of NiAl-NiAlTa Alloys  

NASA Technical Reports Server (NTRS)

Directional solidification of eutectic alloys is a promising technique for producing in-situ composite materials exhibiting a balance of properties. Consequently, the microstructure, creep strength and fracture toughness of directionally solidified NiAl-NiAlTa alloys were investigated. Directional solidification was performed by containerless processing techniques to minimize alloy contamination. The eutectic composition was found to be NiAl-15.5 at% Ta and well-aligned microstructures were produced at this composition. A near-eutectic alloy of NiAl-14.5Ta was also investigated. Directional solidification of the near-eutectic composition resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The off-eutectic alloy exhibited promising compressive creep strengths compared to other NiAl-based intermetallics, while preliminary testing indicated that the eutectic alloy was competitive with Ni-base single crystal superalloys. The room temperature toughness of these two-phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa.

Johnson, D. R.; Chen, X. F.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

1995-01-01

208

Nucleosynthesis of Al26 in massive stars: New Al27 states above ? and neutron emission thresholds  

NASA Astrophysics Data System (ADS)

The 26Al radioisotope is of great importance for understanding the chemical and dynamical evolution of our galaxy. Among the possible stellar sources, massive stars are believed to be the main producer of this radioisotope. Understanding 26Al nucleosynthesis in massive stars requires estimates of the thermonuclear reaction rates of the Al26(n,p)26Mg, Al26(n,?)23Na, and Na23(?,p)26Mg reactions. These reaction rates depend on the spectroscopic properties of 27Al states above the neutron and alpha thresholds. In this context, the Al27(p,p')27Al* reaction was studied at 18 MeV using a high-resolution Enge Split-Pole spectrometer. States from the ground state up to excitation energies of ?14 MeV were populated. While up to the 23Na + ? threshold no additional states are observed, we report for the first time 30 new levels above the 23Na + ? threshold and more than 30 new states above the 26Al + n threshold for which excitation energies are determined with an uncertainty of 4-5 keV.

Benamara, S.; de Séréville, N.; Laird, A. M.; Hammache, F.; Stefan, I.; Roussel, P.; Ancelin, S.; Assié, M.; Coc, A.; Deloncle, I.; Fox, S. P.; Kiener, J.; Lefebvre, L.; Lefebvre-Schuhl, A.; Mavilla, G.; Morfouace, P.; Sánchez-Benítez, Á. M.; Perrot, L.; Sinha, M.; Tatischeff, V.; Vandebrouck, M.

2014-06-01

209

Electronic structure and bonding at the Alterminated Al(111)/Al2O3(0001) interface: A first principles study  

E-print Network

the mechanical properties of an interface, is the ideal work of adhesion, Ï ,[1] which is defined as the bondElectronic structure and bonding at the Al­terminated Al(111)/«­Al2O3(0001) interface: A first to determine the bonding character of the Al­terminated Al(111)/«­Al2O3(0001) interface. By using an optimized

Adams, James B

210

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

211

Analysis of interface trap states in InAlN/AlN/GaN heterostructures  

NASA Astrophysics Data System (ADS)

Gate-source frequency-dependent capacitance and conductance measurements were performed on the In0.17Al0.83N/AlN/GaN heterostructure field-effect transistor with side-Ohmic contacts to study the characteristics of trap states at the interface between InAlN and GaN. The values of interface trap state density and time constant were determined to be (0.96-3.36) × 1013 cm-2 eV-1 and (0.29-1.61) ?s, respectively. We calculated the strain in the InAlN barrier layer under the gate and found that the InAlN barrier layer was compressively strained with the in-plane strain of 1.31%. This is a possible reason for such a high interface trap state density which is not as low as supposed in the lattice-matched heterostructures.

Zhou, Yang; Lin, Zhaojun; Luan, Chongbiao; Zhao, Jingtao; Yang, Qihao; Yang, Ming; Wang, Yutang; Feng, Zhihong; Lv, Yuanjie

2014-09-01

212

Properties and structure of oxidized coatings deposited onto Al-Cu and Al-Mg alloys  

NASA Astrophysics Data System (ADS)

The results of new studies of creating protective oxide coatings based on Al2O3 (Si, Mn) and deposited onto aluminum alloys using electrolyte-plasma oxidation are presented. An analysis is performed by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction, Rutherford backscattering of 4He+ and protons, nanoindentation, scratching, friction coefficient measurements, and acoustic emission measurements. The results demonstrate that the deposited coatings have a high quality, hardness, and wear resistance and a low thermal diffusivity. Apart from Al2O3, the coatings are found to have Si, Mn, C, and Ca. The stoichiometry of the coatings is determined. The density and hardness of the coatings are close to those of ?-Al2O3 in the coating on an Al-Cu (D-16) substrate, and these values of the coating on an Al-Mg (S006) are lower by a factor of 1.5.

Pogrebnyak, A. D.; Kylyshkanov, M. K.; Tyurin, Yu. N.; Kaverina, A. Sh.; Yakushchenko, I. V.; Borisenko, A. A.; Postol'ny, B. A.; Kulik, I. A.

2012-06-01

213

1300 K compressive properties of a reaction milled NiAl-AlN composites  

NASA Technical Reports Server (NTRS)

When B2 crystal-structure nickel aluminide is subjected to high-intensity mechanical ball milling in a liquid nitrogen bath, or 'cryomilling', an NiAl composite is obtained which contains about 10 vol pct AlN particles. This composition arises from the incorporation of N during cryomilling; during subsequent thermomechanical processing, the N reacts with Al. While compressive testing of extruded or isostatically pressed specimens at 1300 K indicated that strength at relatively fast strain rates is slightly dependent on consolidation method, slower strain rates indicate no clear dependency on densification technique: four different consolidation methods were found to yield similar creep strengths. The creep properties of NiAl-AlN are similar to those of the single-crystal Ni-base superalloy NASAIR 100.

Whittenberger, J. Daniel; Arzt, Eduard; Luton, Michael J.

1990-01-01

214

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

NASA Technical Reports Server (NTRS)

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

Copeland, Evan

2008-01-01

215

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

NASA Technical Reports Server (NTRS)

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

Copland, Evan

2008-01-01

216

Influence of reaction with XeF2 on surface adhesion of Al and Al2O3 surfaces  

Microsoft Academic Search

The change in surface adhesion after fluorination of Al and Al2O3 surfaces using XeF2 was investigated with atomic force microscopy. The chemical interaction between XeF2 and Al and Al2O3 surfaces was studied by in situ x-ray photoelectron spectroscopy. Fresh Al and Al2O3 surfaces were obtained by etching top silicon layers of Si?Al and Si?Al2O3 with XeF2. The surface adhesion and

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

2008-01-01

217

Influence of reaction with XeF2 on surface adhesion of Al and Al2O3 surfaces  

Microsoft Academic Search

The change in surface adhesion after fluorination of Al and Al2O3 surfaces using XeF2 was investigated with atomic force microscopy. The chemical interaction between XeF2 and Al and Al2O3 surfaces was studied by in situ x-ray photoelectron spectroscopy. Fresh Al and Al2O3 surfaces were obtained by etching top silicon layers of Si\\/Al and Si\\/Al2O3 with XeF2. The surface adhesion and

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

2008-01-01

218

Wear characteristics of Al-AlN composites produced in-situ by nitrogenation  

NASA Astrophysics Data System (ADS)

In the present scenario most of the parts used in automobile and aerospace industries are made of composites. Aluminium metal has a very high strength to weight ratio. Al-AlN metal matrix composites have excellent mechanical properties like good wear resistance, high hardness and high strength to weight ratio which are obtained from low density of aluminium and high hardness and wear resistance of AlN. Therefore, use of Al-AlN MMC leads to advantages in automobile industries as it reduces fuel consumption and gives better structural strength. The composites can be produced ex-situ by introducing AlN as reinforcement into the metal matrix and in- situ by nitrogenation process. In the present process Al-AlN composites were fabricated by treating molten aluminium with a mixture of CaO and NH4Cl and held at temperature range at 750-930°C and then cast into a metal mould. Addition of CaO to NH4Cl is found to have a more pronounced effect as a nitrogenation agent in comparison with NH4Cl in the molten aluminium in the temperature range of 700- 1000°C. Castings of aluminium and Al-AlN composites were prepared by mixing different ratios of aluminium and NH4Cl, at different casting temperatures and holding time. Wear resistance and hardness of the samples were determined, and microstructure studies were carried out. The composite formed using higher amount of NH4Cl had higher hardness and wear resistance.

Pradhan, S.; Jena, S. K.; Patnaik, S. C.; Swain, P. K.; Majhi, J.

2015-02-01

219

AL ASK A SALMON alaska Salmon  

E-print Network

189 AL ASK A SALMON UNIT 13 alaska Salmon INTRODUCTION Pacific salmon have played an important and pivotal role in the history of Alaska. Salmon, along with mining, timber, and furs, were the keystone now, the abundant salmon resources of this region continue to shape much of the con- temporary lives

220

U-ALS: A Ubiquitous Learning Environment  

ERIC Educational Resources Information Center

The diffusion of the use of the learning virtual environments presents a great potential for the development of an application which meet the necessities in the education area. In view of the importance of a more dynamic application and that can adapt itself continuously to the students' necessities, the "U-ALS" (Ubiquitous Adapted Learning…

Piovesan, Sandra Dutra; Passerino, Liliana Maria; Medina, Roseclea Duarte

2012-01-01

221

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

222

Bierman {ital et al.}Reply:  

SciTech Connect

reply to the Comment by C.H.Dasso et al., Phys. Rev. Lett. 78,XXX(1997). A Reply to the Comment by C.H. Dasso and J. Fern{acute a}ndez-Niello. {copyright} {ital 1997} {ital The American Physical Society}

Bierman, J.D.; Chan, P.; Liang, J.F.; Kelly, M.P.; Sonzogni, A.A.; Vandenbosch, R. [Nuclear Physics Laboratory University of Washington Seattle, Washington 98195 (United States)] [Nuclear Physics Laboratory University of Washington Seattle, Washington 98195 (United States)

1997-05-01

223

(12) United States Patent Grier et al.  

E-print Network

(12) United States Patent Grier et al. US008502132B2 US 8,502,132 B2 Aug. 6, 2013 (10) Patent N0.: (45) Date of Patent: (54) (75) (73) (*) (21) (22) (65) (62) (60) (51) (52) MANIPULATION OF OBJECTS) Assignee: New York University, NeW York, NY (Us) Notice: Subject to any disclaimer, the term ofthis patent

Grier, David

224

(12) United States Patent Vertes et al.  

E-print Network

(12) United States Patent Vertes et al. (54) LASERABLATION ELECTROSPRAY IONIZATION (LAESI) ( *) Notice: Subject to any disclaimer, the term ofthis patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days. lbis patent is subject to a terminal dis- claimer. (21) Appl. No.: 131271,435 Oct. 12, 2011

Vertes, Akos

225

(12) United States Patent Geohegan et al.  

E-print Network

(12) United States Patent Geohegan et al. US008540542B2 US 8,540,542 B2 Sep. 24, 2013 (10) Patent N0.: (45) Date of Patent: (54) TRANSPARENT CONDUCTIVE NANO-COMPOSITES (75) Inventors: David Bruce Research Foundation, Knoxville, TN (US) Notice: Subject to any disclaimer, the term ofthis patent

Geohegan, David B.

226

COMUNICATO STAMPA Tiroide, visite gratuite al Ruggi  

E-print Network

effettuando visite gratuite con ecografia della tiroide presso il Day Service di Patologia Tiroidea, diretto:00 presso il Day Service di Patologia Tiroidea al 4° piano del corpo C-D dell'AOU S. Giovanni di Dio e Ruggi

Costagliola, Gennaro

227

Luminescence in Li? Al ? (PO?)? :Eu(2+).  

PubMed

A series of efficient Li? Al ? (PO?)? :Eu(2+) novel phosphors were synthesized by the facile combustion method. The effects of dopant on the luminescence behavior of Li? Al ? (PO?)? phosphor were also investigated. The phosphors were characterized by X-ray diffraction, field emission scanning electron microscope and photoluminescence techniques. The result shows that all samples can be excited efficiently by near-ultraviolet excitation under 310?nm. The emission was observed for Li? Al ? (PO?)? :Eu(2+) phosphor at 425?nm, which corresponded to the d ? f transition. The concentration quenching of Eu(2+) was observed in Li? Al ? (PO?)? :Eu(2+) when the Eu concentration was at 0.5?mol%. The prepared powders exhibited intense blue emission at the 425?nm owing to the Eu(2+) ion by Hg-free excitation at 310?nm (i.e., solid-state lighting excitation). Consequently, the availability of such a phosphor will significantly help in the development of blue-emitting solid-state lighting applications. PMID:23019178

Shinde, K N; Park, K

2013-01-01

228

AgriculturAl 2013 Annual Report  

E-print Network

Dean of Agriculture and Natural Resources Rutgers, The State University of New Jersey ExecutiveNew Jersey AgriculturAl experimeNt stAtioN 2013 Annual Report #12;To enhance the vitality, health, sustainability, and overall quality of life in New Jersey by developing and delivering practical, effective

Goodman, Robert M.

229

Correction to Rothermund et al. (2005)  

ERIC Educational Resources Information Center

This article reports an error in the article "Retrieval of Incidental Stimulus-Response Associations as a Source of Negative Priming" by Rothermund et al. ("Journal of Experimental Psychology: Learning, Memory, and Cognition," Vol 31(3) May 2005, 482-495). Table 1 (p. 484) was incorrectly typeset. The correct layout is provided. (The following…

Rothermund, Klaus; Wentura, Dirk; De Houwer, Jan

2005-01-01

230

(12) United States Patent Colace et al.  

E-print Network

(12) United States Patent Colace et al. (54) (75) (73) SYSTEM AND METHOD ALLOWING ADVERTISERS, Toluca Lake, CA (US); Scott W. Snell, Hollywood, CA (US); Jeremy Daw, Alta Lorna, CA (US); Dominic Dough-Ming Cheung, South Pasadena, CA (US); Benjamin James Watkins, Torrance, CA (US); Thomas A. Soulanille

Shamos, Michael I.

231

4, 309333, 2008 T. Arsouze et al.  

E-print Network

CPD 4, 309­333, 2008 Neodymium modelling T. Arsouze et al. Title Page Abstract Introduction of the Atlantic thermohaline circulation on neodymium isotopic composition at the Last Glacial Maximum Publications on behalf of the European Geosciences Union. 309 #12;CPD 4, 309­333, 2008 Neodymium modelling T

Paris-Sud XI, Université de

232

Das Faktorisierungsrepr asentationsproblem als Basis kryptographischer Protokolle  

E-print Network

Wolfgang Goethe-Universit at in Frankfurt am Main | von Roger Fischlin aus O#11;enbach am Main | Frankfurt am Main 2002 D F 1 #12; ii Vom Fachbereich Mathematik der Johann Wolfgang Goethe-Universit at als Mitarbeit von 1998 bis 2001 in der Gruppe von Prof. Dr.Schnorr am Fachbereich Ma- thematik der J.W.Goethe

233

Ternary Dy-Er-Al magnetic refrigerants  

DOEpatents

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

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

1995-07-25

234

(12) United States Patent Vertes et al.  

E-print Network

) PCTFiled: Jan. 26, 2006 (86) PCTNo.: PCT/US2006/002483 § 371 (c)(1), (2), (4) Date: Jul. 20, 2007 (87) PCT Pub. No.: W02006/081240 PCT Pub. Date: Aug. 3, 2006 (65) Prior Publication Data US 2008/0149822 Al lun

Vertes, Akos

235

The Rail Gun Muad Al Khaldi  

E-print Network

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

Masoudi, Husain M.

236

(12) United States Patent Bauer et al.  

E-print Network

Intuit's Quicken InsureMarket Offering Online Auto Policies in 6 States, Dec. 1998, Business Wire(12) United States Patent Bauer et al. (54) APPARATUS FOR INTERNET ON-LINE INSURANCE POLICY SERVICE * 912000 OTHER PUBLICATIONS Pasher, Auto Web site takes off, Mar. 1998, National Underwriter (Propert

Shamos, Michael I.

237

(12) United States Patent Black et al.  

E-print Network

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

Shamos, Michael I.

238

Eigennutz als Triebfeder des Wohlstands: Die \\  

Microsoft Academic Search

Die empirische Prüfung theoretischer Forschungsergebnisse wirft in der Ökonomie - wie bei jeder Sozialwissenschaft - Probleme auf. Anders als in den Naturwissenschaften können volkswirtschaftliche Problemstellungen kaum in Labors nachgestellt werden. Seit einigen Jahren nutzen Ökonomen allerdings die Erfahrungen der Psychologie mit stilisierten Experimenten, um zumindest ihre grundlegenden Verhaltenshypothesen testen zu können. Dieser Beitrag stellt ein einfaches Hörsaal-Experiment vor, das Adam

Roland Kirstein; Dieter Schmidtchen

2002-01-01

239

Clinical trials in ALS: an overview.  

PubMed

Clinical trials in amyotrophic lateral sclerosis (ALS) have been conducted for over half a century now and have incorporated a wide variety of drugs. Most of these trials have had negative results and a cure remains elusive. The explosion in our understanding of molecular biology and parallel developments in clinical epidemiology have opened up a vast number of novel therapeutic strategies. However, advances in statistical analysis, computing, and global communications have also put greater pressure on scientific investigators to improve the design and implementation of clinical trials so that they permit rigorous testing of hypotheses within a solid ethical framework. This article documents the first published trial for all drugs tried clinically in the treatment of ALS, focusing in more detail on the large, multicenter trials of recent years, namely those involving riluzole, ciliary neurotrophic factor, insulin-like growth factor-I, brain-derived neurotrophic factor, and SR57746A. The problems in the design of trials in ALS are discussed, including the selection of end points and surrogate markers of disease progression, and the major parameters in ALS assessment are reviewed. PMID:11442325

Turner, M R; Parton, M J; Leigh, P N

2001-06-01

240

(12) United States Patent Vertes et al.  

E-print Network

(12) United States Patent Vertes et al. (54) NANOPHOTONIC PRODUCTION, MODULATION AND SWITCHING a quasi-periodic antenna array with ion yields that show pro- found dependence on the plane oflaser light polarization and the angle of incidence. By providing photonic ion sources, this enables enhanced control

Vertes, Akos

241

Schler et al 2001 Mycol Arbuscular mycorrhiza  

E-print Network

vulgaris colonized by arbuscular mycorrhizal fungi vesicle arbuscules (c) D. Redecker 10µm #12;Auxilary. Redecker, K. Wex10µm #12;SEM of arbuscles From Mycorrhizal Symbiosis #12;Devonian Fossil Modern Glomales Remy, Taylor et al. 1994 #12;From Gallaud 1905Arum type Paris type #12;AM Hyphae From Mycorrhizal

California at Berkeley, University of

242

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

243

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

244

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

245

Qiu & al. Basal angiosperm phylogeny55 (4) November 2006: 837856 INTRODUCTION  

E-print Network

, 1999; P. Soltis & al., 1999; Barkman & al., 2000; Graham & Olmstead, 2000; Savolainen & al., 2000., 1999; Barkman & al., 2000; Graham & Olmstead, 2000; D. Soltis & al., 2000; Zanis & al., 2002; Borsch

246

Electrochemical formation of Al-Tm intermetallics in eutectic LiCl-KCl melt containing Tm and Al ions  

NASA Astrophysics Data System (ADS)

This work focuses on investigating the electrochemical formation of Al-Tm and Al-Li-Tm alloys in LiCl-KCl-AlCl3-Tm2O3 melt on both W and Al electrodes. Thermodynamic calculation and electrochemical behavior of LiCl-KCl melt containing both AlCl3 and Tm2O3 showed that AlCl3 can chlorinate Tm2O3 to release Tm(III) ions. Three kinds of Al-Tm intermetallics at about -1.26, -1.32 and -1.43 V were detected by means of various electrochemical measurement techniques, i.e. cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry. Potentiostatic and galvanostatic electrolysis were carried out on Al and W electrodes to prepare Al-Tm and Al-Li-Tm alloys, respectively. The composition of Al-Li-Tm alloys was analyzed by inductive coupled plasma atomic emission spectrometer (ICP-AES).

Li, Xing; Yan, Yong-De; Zhang, Mi-Lin; Tang, Hao; Ji, De-Bin; Han, Wei; Xue, Yun; Zhang, Zhi-Jian

2014-09-01

247

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

248

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

NASA Astrophysics Data System (ADS)

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 factor ? at aluminum site III is related to the shifting of atoms from positions on the (001) lattice planes, which has been proposed to enhance stability in Al_3Zr and Al_3Hf. From site-dependent spin-lattice relaxation times (T_1's) and the Korringa relation we have obtained site-dependent information about the conduction electrons in these materials. T_1's for site III are particularly long, indicating a possible stability mechanism due to hybridization-bap formation. However, the hybridization-gap behavior is not as strong as in the corresponding DO_22 materials such as Al_3V. We compare to measurements for several related Al-rich V and Fe aluminides, and describe NMR results for these materials.

Lue Ross, Chin Shan, Jr.

2001-03-01

249

Some TEM observations of Al2O3 scales formed on NiCrAl alloys  

NASA Technical Reports Server (NTRS)

The microstructural development of Al2O3 scales on NiCrAl alloys has been examined by transmission electron microscopy. Voids were observed within grains in scales formed on a pure NiCrAl alloy. Both voids and oxide grains grew measurably with oxidation time at 1100 C. The size and amount of porosity decreased towards the oxide-metal growth interface. The voids resulted from an excess number of oxygen vacancies near the oxidemetal interface. Short-circuit diffusion paths were discussed in reference to current growth stress models for oxide scales. Transient oxidation of pure, Y-doped, and Zr-doped NiCrAl was also examined. Oriented alpha-(Al, Cr)2O3 and Ni(Al, Cr)2O4 scales often coexisted in layered structures on all three alloys. Close-packed oxygen planes and directions in the corundum and spinel layers were parallel. The close relationship between oxide layers provided a gradual transition from initial transient scales to steady state Al2O3 growth.

Smialek, J.; Gibala, R.

1979-01-01

250

Photoemission Characterization of Al/Alq3 and Al/LiF/Alq3 Interfaces  

NASA Astrophysics Data System (ADS)

The interfaces formation of Al on tris-(8-hydroxyquinoline) aluminium Alq3 and Al on LiF/Alq3 is investigated by using X-ray and ultraviolet photoemission spectrascopy (XPS and UPS). We observed significant modification of O1s, N1s and Al2p core level spectra as Al was directly deposited on the Alq3 surface. The Alq3 molecular orbital features in the UPS spectra were also quikly destroyed. In contract, a dramatically different behavior was observed for Al on the LiF/Alq3 interface. With only about 5Åor less of LiF deposited on the Alq3 as a buffer layer, the reaction between Al and Alq3 is significantly suppressed. A well-defined gap state is formed in UPS spectra. The Alq3 molecular orbital features in UPS shift to higher binding energies but remain easily recognizable. Both the core level spectra and the gap state suggest that the Alq3 anion is formed in the presence of Al and LiF.

Yan, Li; Le, Q. T.; Gao, Yongli; Mason, M. G.; Tang, C. W.

2000-03-01

251

Ion irradiation induced Al-Ti interaction in nano-scaled Al/Ti multilayers  

NASA Astrophysics Data System (ADS)

Interactions induced in Al/Ti multilayers by implantation of Ar ions at room temperature were investgated. Initial structures consisted of (Al/Ti) × 5 multilayers deposited by d.c. ion sputtering on Si(1 0 0) wafers, to a total thickness of ?250 nm. They were irradiated with 200 keV Ar+ ions, to the fluences from 5 × 1015 to 4 × 1016 ions/cm2. It was found that ion irradiation induced a progressed intermixing of the multilayer constituents and Al-Ti nanoalloying for the highest applied fluence. The resulting nanocrystalline structure had a graded composition with non-reacted or interdiffused Al and Ti, and ?-AlTi and AlTi3 intermetallic phases. Most intense reactivity was observed around mid depth of the multilayers, where most energy was deposited by the impact ions. It is presumed that Al-Ti chemical reaction is triggered by thermal spikes and further enhanced by chemical driving forces. The applied processing can be interesting for fabrication of tightly bond multilayered structures with gradual changes of their composition and properties.

Milosavljevi?, M.; Stojanovi?, N.; Peruško, D.; Timotijevi?, B.; Toprek, D.; Kova?, J.; Draži?, G.; Jeynes, C.

2012-01-01

252

An Al-inducible MATE gene is involved in external detoxification of Al in rice.  

PubMed

A number of plant species, including rice, secretes citrate from roots in response to Al stress. Here we characterized the functions of a gene, OsFRDL4 (Os01g0919100) that belongs to the multidrug and toxic compound extrusion (MATE) family in rice (Oryza sativa). Heterologous expression in Xenopus oocyte showed that the OsFRDL4 protein was able to transport citrate and was activated by Al. The expression level of the OsFRDL4 gene in roots was very low in the absence of Al, but was greatly enhanced by Al after short exposure. Furthermore, the OsFRDL4 expression was regulated by ART1, a C2H2-type zinc finger transcription factor for Al tolerance. Transient expression of OsFRDL4 in onion epidermal cells showed that it localized to the plasma membrane. Immunostaining showed that OsFRDL4 was localized in all cells in the root tip. These expression patterns and cell specificity of localization of OsFRDL4 are different from other MATE members identified previously. Knockout of OsFRDL4 resulted in decreased Al tolerance and decreased citrate secretion compared with the wild-type rice, but did not affect citrate concentration in the xylem sap. Furthermore, there is a positive correlation between OsFRDL4 expression level and the amount of citrate secretion in rice cultivars that are differing in Al tolerance. Taken together, our results show that OsFRDL4 is an Al-induced citrate transporter localized at the plasma membrane of rice root cells and is one of the components of high Al tolerance in rice. PMID:21880027

Yokosho, Kengo; Yamaji, Naoki; Ma, Jian Feng

2011-12-01

253

Solidification processing of intermetallic Nb-Al alloys  

NASA Technical Reports Server (NTRS)

Several Nb-Al alloys, including single-phase NbAl3 and the eutectic of Nb2Al and NbAl3, were prepared either by nonconsumable arc melting in Ar or by zone processing in He following initial induction melting and rod casting, and the effect of the solidification route on the microstructure and room-temperature mechanical properties of these alloys was investigated. Automated control procedures and melt conditions for directional solidification of NbAl3 and the Nb2Al/Nb3Al eutectic were developed; high purity and stoichiometry were obtained. The effects of ternary additions of Ti and Ni are described.

Smith, Preston P.; Oliver, Ben F.; Noebe, Ronald D.

1992-01-01

254

Valence subband coupling effect on polarization of spontaneous emissions from Al-rich AlGaN/AlN quantum wells.  

PubMed

The optical polarization properties of Al-rich AlGaN/AlN quantum wells (QWs) were investigated using the theoretical model based on the k·p method. Numerical results show that there is valence subband coupling which can influence the peak emission wavelength and emission intensity for TE and TM polarization components from Al-rich AlGaN/AlN QWs. Especially the valence subband coupling could be strong enough when CH1 is close to HH1 and LH1 subbands to modulate the critical Al content switching dominant emissions from TE to TM polarization. It is believed that the valence subband coupling may give important influence on polarization properties of spontaneous emissions and should be considered in designing high efficiency AlGaN-based ultraviolet (UV) LEDs. PMID:23262689

Lu, Huimin; Yu, Tongjun; Yuan, Gangcheng; Jia, Chuanyu; Chen, Genxiang; Zhang, Guoyi

2012-12-01

255

Density of Low-Temperature KF-AlF3 Aluminum Baths with Al2O3 and AlPO4 Additives  

NASA Astrophysics Data System (ADS)

The density of the KF-AlF3 melts of various KF and AlF3 ratio with Al2O3 and AlPO4 addition has been measured using the Archimedean method. On the basis of the obtained density data the molar volumes of the melts were calculated. These molar volumes decrease with concentration of Al2O3 or AlPO4. In the system containing AlPO4, the relation between cryolite ratios (CRs) vs slopes of molar volume trend lines was identified with excellent correlation factor of R 2 = 0.9844, while in the system containing Al2O3 a discontinuity at CR = 2.5 can be observed.

Vasková, Zuzana; Kontrík, Martin; Mlynáriková, Jarmila; Bo?a, Miroslav

2015-02-01

256

MATH 22AL Fall 2012 Dr. Dad-del  

E-print Network

MATH 22AL Fall 2012 Dr. Dad-del Important Information about MAT22A and MAT22AL MATH 22AL is an on line computer lab for MATH 22AL. This course uses MATLAB to reinforce the concepts learned in MATH22A. All MAT 22A students are required to take 22AL, unless they have taken Eng 6 or have a good knowledge

Goldwyn, Eli

257

Characterization of Ultrathin Films of -Al2O3 and the Chemistry of 1,3-Butadiene on NiAl(001) and -Al2O3  

E-print Network

Characterization of Ultrathin Films of -Al2O3 and the Chemistry of 1,3-Butadiene on NiAl(001) and -Al2O3 Michelle M. Ivey, Kathryn A. Layman, Armen Avoyan, Heather C. Allen, and John C. HemmingerVine, California 92697 ReceiVed: October 3, 2002; In Final Form: March 27, 2003 Ultrathin films of -Al2O3 grown

258

TRANSCRIPTIONAL ANALYSIS BETWEEN TWO WHEAT NEAR-ISOGENIC LINES CONTRASTING IN ALUMINUM (AL) TOLERANCE UNDER AL STRESS  

Technology Transfer Automated Retrieval System (TEKTRAN)

To understand the mechanisms of aluminum (Al) tolerance and identify genes responsible for Al tolerance in wheat (Triticum aestivum L.), suppression subtractive hybridization (SSH) libraries were constructed from Al-stressed roots for two wheat near- isogenic lines (NILs), Chisholm-T (Al-tolerant) a...

259

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

E-print Network

(5.5) BRAZING OF METALLIC-INTERMETALLIC LAMINATE (MIL) Ti-6Al-4V/Al3Ti COMPOSITES L. Krüger*, F to their excellent specific mechanical properties, metallic-intermetallic laminate (MIL) composites composed of Ti-6Al-4V and Al3Ti intermetallic layers are very attractive candidates in lightweight, high performance

Meyers, Marc A.

260

FTIR and 27 Al MAS NMR analysis of the effect of framework Al-and Si-defects  

E-print Network

Torino, Via P. Giuria 7, 10125 Torino, Italy a r t i c l e i n f o Article history: Received 3 January for analysis of the population of framework Al- and Si-related defective sites. Beside framework Al atoms in regular Td coordination, perturbed Td coordinated Al atoms and partly extra-framework Al species

Sklenak, Stepan

261

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

Microsoft Academic Search

The structures and properties of Al n , Al{\\/n +}, Al{\\/n -} ( n=1,5) clusters have been investigated by using the Linear Combination of Gaussian Type Orbitals (LCGTO) method, considering Local (LSD) and Non Local (NLSD) Spin Density Approximations and employing a Model Core Potential (MCP) that allows the explicit treatment of 3 s 2 3 p 1 valence electrons.

Patrizia Calaminici; Nino Russo; Marirosa Toscano

1995-01-01

262

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

E-print Network

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

Elkatsha, Markus Fawzy Fahmy

2000-01-01

263

Fabrication and properties of functionally graded NiAl/Al2O3 composites  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

264

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

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

265

Communication Support for People with ALS  

PubMed Central

Almost all people with amyotrophic lateral sclerosis (ALS) experience a motor speech disorder, such as dysarthria, as the disease progresses. At some point, 80 to 95% of people with ALS are unable to meet their daily communication needs using natural speech. Unfortunately, once intelligibility begins to decrease, speech performance often deteriorates so rapidly that there is little time to implement an appropriate augmentative and alternative communication (AAC) intervention; therefore, appropriate timing of referral for AAC assessment and intervention continues to be a most important clinical decision-making issue. AAC acceptance and use have increased considerably during the past decade. Many people use AAC until within a few weeks of their deaths. PMID:21603029

Beukelman, David; Fager, Susan; Nordness, Amy

2011-01-01

266

Stress evolution during ultrasonic Al ribbon bonding  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

267

Quasielastic scattering in PrAl3  

NASA Astrophysics Data System (ADS)

Using the long-wavelength polarisation analysis neutron spectrometer (LONGPOL) fitted with time-of-flight energy analysis, the crystal field excitation spectrum of the rare earth trialuminide PrAl3 was measured, and transitions of 4.5 and 3.7 meV were observed to take place between states of the Pr3+ ion. In addition, the neutron polarisation analysis of the elastic scattering resulted in a clearer separation into nuclear elastic and magnetic quasielastic components, the latter resulting from the neutrons' interaction with excited Pr3+ ions. Calculations of transition probabilities were performed, and this led to the conclusion that the quasielastic scattering and crystal field transitions had been successfully observed and distinguished from other scattering events in PrAl3.

Goossens, D. J.; Kennedy, S. J.; Hicks, T. J.

1998-04-01

268

Status of the AlCap experiment  

E-print Network

The AlCap experiment is a joint project between the COMET and Mu2e collaborations. Both experiments intend to look for the lepton-flavour violating conversion $\\mu + A \\rightarrow e + A$, using tertiary muons from high-power pulsed proton beams. In these experiments the products of ordinary muon capture in the muon stopping target are an important concern, both in terms of hit rates in tracking detectors and radiation damage to equipment. The goal of the AlCap experiment is to provide precision measurements of the products of nuclear capture on Aluminium, which is the favoured target material for both COMET and Mu2e. The results will be used for optimising the design of both conversion experiments, and as input to their simulations. Data was taken in December 2013 and is currently being analysed.

Litchfield, R Phillip

2015-01-01

269

Development of SiAlON materials  

NASA Technical Reports Server (NTRS)

Cold pressing and sintering techniques were used to produce ceramic test specimens in which the major phase was either Si3N4 or a solid solution having the beta Si3N4 structure. Additional components were incorporated to promote liquid phase sintering. Glass and/or crystalline phase were consequently retained in boundaries between Si3N4 grains which largely determined the physical properties of the bodies. Systems investigated most extensively included R-Si-Al-O-N (R = rare earth element) Zr-Si-Al-O-N, Y-Si-Be-O-N, and R1-R2-Si-O-N. Room temperature and 1370 C modulus of ruptured, 1370 C creep, and oxidation behavior are discussed in terms of phase relationships in a parent quinery, and relavent oxide systems.

Layden, G. K.

1979-01-01

270

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

271

Diffusion in single crystal of melilite: interdiffusion of Al + Al vs. Mg + Si  

Microsoft Academic Search

Interdiffusion coefficients of Al + Al vs. Mg + Si in the gehlenite–åkermanite system of melilite were determined by coupled\\u000a annealing of synthesized end-member single crystals. The observed diffusion coefficients for a couple-annealed sample vary\\u000a for about 2 orders of magnitude, showing strong dependence on the gehlenite–åkermanite composition: diffusion coefficient\\u000a observed at 1350 °C, for example, is 3 × 10?13

H. Nagasawa; T. Suzuki; M. Ito; M. Morioka

2001-01-01

272

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

273

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

274

GaN on Si Substrate with AlGaN\\/AlN Intermediate Layer  

Microsoft Academic Search

A single crystal GaN thin film was successfully grown on a Si (111) substrate by means of atmospheric pressure metalorganic chemical vapor deposition. Though there is a large difference in thermal expansion coefficients between GaN and Si, an intermediate layer consisting of AlN and AlGaN improved the quality of GaN on Si and reduced meltback etching during growth. Pits and

Hiroyasu Ishikawa; Guang-Yuan Zhao; Naoyuki Nakada; Takashi Egawa; Takashi Jimbo; Masayoshi Umeno

1999-01-01

275

Electronic and magnetic properties of AlFe 3 and AlFe 3N nitride  

Microsoft Academic Search

Self-consistent band structure calculations were performed for the metal aluminide AlFe3 (in the fcc structure) and the nitride AlFe3N (perovskite-like nitride) at several lattice parameters in order to obtain the electronic structure and magnetic properties of these compounds. In this study we have employed the full potential linear augmented plane wave (FPLAPW) and the linear muffin-tin orbital (LMTO-ASA) methods. Our

C. A. Kuhnen; A. V. dos Santos

2004-01-01

276

Drilling of Al—Mg—Cu alloys and Al—Mg—Cu\\/SiC composites  

Microsoft Academic Search

Metal matrix composites are widely used in engineering applications including automotive, aircraft, and military industries. In this study, different Al—4 wt%Mg—Cu alloys, and Al—4 wt%Mg—Cu\\/SiC composites were drilled on a vertical drilling machine using moderate speed and general purpose high-speed steel tools. The machinability parameters studied in this research were drilling forces (torque and thrust force) and surface roughness of

Abdalla Alrashdan; Ahmad T. Mayyas; Adel Mahamood Hassan; Mohammed T. Hayajneh

2011-01-01

277

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

278

DX centers in AlAs and GaAs-AlAs selectively doped superlattices  

NASA Astrophysics Data System (ADS)

DX centers have been investigated using deep level transient spectroscopy (DLTS) in Si doped AlAs and in selectively doped GaAs-AlAs superlattices (SLs) grown by molecular beam epitaxy. The activation energy for thermal emission is E_a = 0.42 eV in both the SLs and AlAs layers. For the first time a study of the capture in a SL reveals a capture activation energy E_cap = 0.36 cV, which locates the DX at E_t? 60 meV below the conduction miniband. Taking into account the measured energies and trap concentrations, we show that the DX observed in the SLs lies in the AlAs layers. Des mesures de spectroscopie capacitives effectuées sur AlAs et sur des super-réseaux (SR) GaAs-AlAs dopés sélectivement et épitaxiés par jets moléculaires montrent que le centre DX a une énergie apparente E_a = 0.42 eV aussi bien dans AlAs que dans les SR. Pour la première fois, une étude de la capture menée sur un SR nous permet de remonter à l'énergie d'activation de la section efficace de capture qui est dans notre cas de 0.36 eV, ce qui positionne le DX à E_t? 60 meV de la minibande de conduction. La nature et la position de DX sont discutées en tenant compte de l'énergie et de la concentration du DX pour chaque structure, et nous montrons que le DX observé est lié au silicium dans les couches AlAs.

Ababou, S.; Marchand, J. J.; Mayet, L.; Guillot, G.; Mollot, F.

1991-07-01

279

Structure and ductility of TiAl  

SciTech Connect

The effect of structural factors (grain size and grain boundary structure) and strain rate on the deformation mechanism and ductility of TiAl in the temperature range of brittle-to-ductile transition and at room temperature was systematically investigated. It has been established that it is possible to substantially affect the deformation mechanism and ductility of this intermetallic by controlling structural factors, particularly the grain size, and varying the strain rate.

Imayev, R.; Salishchev, G.; Imayev, V.; Shagiev, M.; Kuznetzov, A. [Inst. for Metals Superplasticity Problems, Ufa (Russian Federation)

1995-12-31

280

Euklid als Physiker: Die Realgeltung der Geometrie  

NASA Astrophysics Data System (ADS)

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

Genz, Henning

281

INTRODUCCION AL LENGUAJE PROLOG 1. Introduccion 2  

E-print Network

. Prolog y el paradigma de la Programaci´on L´ogica 6 3.1. Sintaxis´on En este documento se realiza una breve introducci´on al lenguaje de programaci´on Prolog, con el objetivo fundamental de mostrar c´omo se da el paso desde el concepto de programaci´on l´ogica "pura

Camacho, David

282

United States Patent [19] Carlson et al.  

E-print Network

United States Patent [19] Carlson et al. [11] Patent Number: 4,523,230 [45] Date of Patent: Jun. 11 ............. 358/160, 163; 166; 167, 358/905, 21 R, 36; 382/49, 54 [56] References Cited U.S. PATENT DOCUMENTS 4 signals. 24 Claims, 8 Drawing Figures #12;U.S. Patent Jun. 11, 1985 Sheet 1 of 4 4,523,230 #12;U.S. Patent

Adelson, Edward

283

United States Patent [19] Burt et al.  

E-print Network

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

Adelson, Edward

284

Al Backlighter Characterization at the Omega Laser  

Microsoft Academic Search

We have characterized He- and H-like Al emission for various laser illuminations at the Omega laser with the goal of optimizing the ability to backlight low-atomic-number (low-Z) materials such as beryllium for fusion ignition studies. The conversion efficiency to Lyman alpha at 1.73 keV has been determined for 1, 2, 4, and 7 laser beams, i.e., as a function of

Jim Cobble

2005-01-01

285

ACCURATE BUILDING OUTLINES FROM ALS DATA  

Microsoft Academic Search

Building detection from airborne laser scanner (ALS) data is a well-studied problem. Most existing building detection techniques rely on the generation of a digital terrain model (DTM) and a digital surface model (DSM) from last-pulse laser scanner data. The two are compared to form a normalised DSM (nDSM), from which the buildings are detected by use of a simple height

286

Semiconducting Al transition-metal quasicrystals  

Microsoft Academic Search

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)

M. Krajcí; J. Hafner

2003-01-01

287

Roll Casting of Al25%Si  

Microsoft Academic Search

Strip casting of Al-25%Si strip was tried using an unequal diameter twin roll caster. The diameter of the lower roll (large roll) was 1000 mm and the diameter of the upper roll (small roll) was 250 mm. Roll material was mild steel. The sound strip could be cast at the speeds ranging from 8 m\\/min to 12 m\\/min. The strip

Toshio Haga; Hideto Harada; Hisaki Watari

2011-01-01

288

Redistribution of Ti and Al in deuterium charged TiAl  

SciTech Connect

The redistribution of titanium and aluminum in a single-phase TiAl alloy that has been exposed to a high pressure of deuterium gas at high temperature is studied. The microstructure in the as-received, uncharged condition consisted of single-phase gamma TiAl grains and a random distribution of precipitates. Precipitates were distributed throughout the matrix and along the grain boundaries. The chemistry of the precipitates varied considerably; some were rich in Al, while other were mostly Ti with some Si and Al. The dislocation density in most grains was low, although in a few grains a high dislocation density was observed. FCC deuterides with a lattice parameter of 0.45 nm form in a Ti-52.1Al-2.1Ta (at. pct) alloy after exposure to 1.38 MPa of deuterium gas at 650 C for 213 hr. The structure and lattice parameter are consistent with the formation of Ti(l)D2. The deuterides that form in this alloy are enriched in Ti and deficient in Al and Ta compared to the deuteride-free matrix. Regions of the matrix contiguous with the deuterides have a correspondingly enhanced aluminum and tantalum concentration. 10 refs.

Legzdina, D.; Robertson, I.M.; Birnbaum, H.K. (Illinois, University, Urbana (United States))

1992-06-01

289

Softening Kinetics in High Al and High Al-Nb-Microalloyed Steels  

NASA Astrophysics Data System (ADS)

Double-hit torsion tests were performed in order to study the effect of high Al levels (up to 2 wt.%) and Nb microalloying (up to 0.07 wt.%) on the static softening kinetics of 0.2%C-2%Mn steels. The addition of 1%Al leads to a delay in the softening kinetics due to solute-drag effect, equivalent to that exerted by 0.027%Nb. For the 2%Al steels, at temperatures below 1000 °C, ? ? ? phase transformation occurs after deformation, resulting in a larger retardation of the softening kinetics. At temperatures higher than 1000 °C, Nb in solid solution also contributes to the retardation of the static softening kinetics, and at lower temperatures NbC strain-induced precipitation leads to incomplete softening for the 1%Al steel, and to a complex interaction between softening, phase transformation, and NbC strain-induced precipitation for the 2%Al-Nb steels. The effect of Al on the static softening kinetics was quantified and introduced in a model developed in previous works for the prediction of the austenite microstructural evolution. In order to validate the results of the model, multipass torsion tests were carried out at conditions representative of hot strip and plate rolling mills. Model predictions show reasonable agreement with the results obtained at different deformation conditions.

Pereda, B.; Aretxabaleta, Z.; López, B.

2015-03-01

290

Influence of Al fraction on photoemission performance of AlGaN photocathode.  

PubMed

To research the photoemission performance of a transmission-mode Al(1-x)Ga(x)N photocathode, Al0.24Ga0.76N and GaN photocathodes with the same structure were activated, their spectral responses were measured using a multi-information measurement system at room temperature, and the photocathode parameters were obtained by fitting quantum efficiency curves. The results showed that both the reflective-mode and transmission-mode spectral responses of the AlGaN photocathode were lower than those of the GaN photocathode. Compared with the GaN photocathode, the short-wavelength spectral response of the Al0.24Ga0.76N photocathode was less seriously affected by lattice defects between the buffer and emission layers. The Al atom at the AlGaN photocathode surface could affect the optimal Cs adsorption position, which mainly affects the surface electron escape probability of the photocathode. PMID:24921126

Hao, Guanghui; Chang, Benkang; Shi, Feng; Zhang, Junju; Zhang, Yijun; Chen, Xinlong; Jin, Muchun

2014-06-10

291

A comparative wear study on Al-Li and Al-Li/SiC composite  

SciTech Connect

Aluminum-lithium based unreinforced (Al-8090) alloy and Al-8090/SiCp/17 vol.% metal matrix composite produced by extrusion after spray co-deposition. A dry ball-on disk wear test was carried out for both alloy and composite. The tests were performed against an Al{sub 2}O{sub 3} ball, 10 mm in diameter, at room temperature and in laboratory air conditions with a relative humidity of 40-60%. Sliding speed was chosen as 1.0 ms{sup ?1} and normal loads of 1.0, 3.0 and 5.0 N were employed at a constant sliding distance of 1000 m. The wear damage on the specimens was evaluated via measurement of wear depth and diameter. Microstructural and wear characterization was carried out via scanning electron microscopy (SEM). The results showed that wear loss of the Al-8090/SiC composite was less than that of the Al-8090 matrix alloy. Plastic deformation observed on the wear surface of the composite and the matrix alloy, and the higher the applied load the greater the plastic deformation. Scanning electron microscopy examinations of wear tracks also reveal that delamination fracture was the dominant wear mechanism during the wear progression. Friction coefficient was maximum at the low applied load in the case of the Al-8090/SiC composite while a gradual increase was observed with applied load for the matrix alloy.

Okumus, S. Cem, E-mail: cokumus@sakarya.edu.tr; Karslioglu, Ramazan, E-mail: cokumus@sakarya.edu.tr; Akbulut, Hatem, E-mail: cokumus@sakarya.edu.tr [Sakarya University Engineering Faculty, Department of Metallurgical and Materials Engineering, Esentepe Campus, 54187, Sakarya (Turkey)

2013-12-16

292

A comparative wear study on Al-Li and Al-Li/SiC composite  

NASA Astrophysics Data System (ADS)

Aluminum-lithium based unreinforced (Al-8090) alloy and Al-8090/SiCp/17 vol.% metal matrix composite produced by extrusion after spray co-deposition. A dry ball-on disk wear test was carried out for both alloy and composite. The tests were performed against an Al2O3 ball, 10 mm in diameter, at room temperature and in laboratory air conditions with a relative humidity of 40-60%. Sliding speed was chosen as 1.0 ms-1 and normal loads of 1.0, 3.0 and 5.0 N were employed at a constant sliding distance of 1000 m. The wear damage on the specimens was evaluated via measurement of wear depth and diameter. Microstructural and wear characterization was carried out via scanning electron microscopy (SEM). The results showed that wear loss of the Al-8090/SiC composite was less than that of the Al-8090 matrix alloy. Plastic deformation observed on the wear surface of the composite and the matrix alloy, and the higher the applied load the greater the plastic deformation. Scanning electron microscopy examinations of wear tracks also reveal that delamination fracture was the dominant wear mechanism during the wear progression. Friction coefficient was maximum at the low applied load in the case of the Al-8090/SiC composite while a gradual increase was observed with applied load for the matrix alloy.

Okumus, S. Cem; Karslioglu, Ramazan; Akbulut, Hatem

2013-12-01

293

Room Temperature Radiolytic Synthesized Cu@CuAlO2-Al2O3 Nanoparticles  

PubMed Central

Colloidal Cu@CuAlO2-Al2O3 bimetallic nanoparticles were prepared by a gamma irradiation method in an aqueous system in the presence of polyvinyl pyrrolidone (PVP) and isopropanol respectively as a colloidal stabilizer and scavenger of hydrogen and hydroxyl radicals. The gamma irradiation was carried out in a 60Co gamma source chamber with different doses up to 120 kGy. The formation of Cu@CuAlO2-Al2O3 nanoparticles was observed initially by the change in color of the colloidal samples from colorless to brown. Fourier transform infrared spectroscopy (FTIR) confirmed the presence of bonds between polymer chains and the metal surface at all radiation doses. Results of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD) showed that Cu@CuAlO2-Al2O3 nanoparticles are in a core-shell structure. By controlling the absorbed dose and precursor concentration, nanoclusters with different particle sizes were obtained. The average particle diameter increased with increased precursor concentration and decreased with increased dose. This is due to the competition between nucleation, growth, and aggregation processes in the formation of nanoclusters during irradiation. PMID:23109893

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

2012-01-01

294

Redistribution of Ti and Al in deuterium charged TiAl  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

295

Reactive HIPIMS with auxiliary Al electrode for ZnO:Al thin film deposition  

NASA Astrophysics Data System (ADS)

In this paper a new technique is proposed for precise doping control of ZnO:Al thin films deposited in reactive High Power Impulse Magnetron Sputtering (HIPIMS). An auxiliary aluminum electrode was added to a reactive Ar/O2 pulsed magnetron with planar Zn target in order to obtain a controlled doping of ZnO films. Al neutral density in gas phase has been controlled by the discharge current and the biasing voltage on the auxiliary electrode (which influence the ion bombardment of the electrode) and measured by laser resonant absorption spectroscopy. The fraction of Al dopant in the deposited films was estimated by X-ray Photoelectron Spectroscopy (XPS) measurements. The goal of this work was to correlate Al density measured in the gas phase with Al concentration in the deposited films. It was also investigated the effect of the aluminum concentration on the structural, electrical and optical properties of ZnO:Al thin films deposited by HIPIMS. The internal microstructure and chemical composition of the deposited films was examined by X-ray difractometry (XRD) and X-ray Photoelectron Spectroscopy (XPS). The optical properties of the deposited films were studied by UV/VIS and photoluminescence spectroscopy.

Tiron, Vasile; Costin, Claudiu; Sirghi, Lucel; Popa, Gheorghe

2012-09-01

296

TEM and HRTEM Characterization of TiAl Diffusion Bonds Using Ni/Al Nanolayers.  

PubMed

Diffusion bonding of TiAl alloys can be enhanced by the use of reactive nanolayer thin films as interlayers. Using these interlayers, it is possible to reduce the conventional bonding conditions (temperature, time, and pressure) and obtain sound and reliable joints. The microstructural characterization of the diffusion bond interfaces is a fundamental step toward understanding and identifying the bonding mechanisms and relating them to the strength of the joints. The interface of TiAl samples joined using Ni/Al nanolayers was characterized by transmission electron microscopy and scanning transmission electron microscopy. Microstructural characterization of the bond revealed that the interfaces consist of several thin layers of different composition and grain size (nanometric and micrometric). The bonding temperature (800, 900, or 1,000°C) determines the grain size and thickness of the layers present at the interface. Phase identification by high-resolution transmission electron microscopy combined with fast Fourier transform and electron energy-loss spectroscopy analyses reveals the presence of several intermetallic compounds: AlTiNi, NiAl, and Al2TiNi. For bonds produced at 800 and 900°C, nanometric grains of Ti were detected at the center of the interface. PMID:25170561

Simões, Sónia; Viana, Filomena; Ramos, Ana S; Vieira, Maria T; Vieira, Manuel F

2015-02-01

297

Fabrication of NiAl Microreactors  

SciTech Connect

Chemical microreactors offer opportunities for portable powder generation, on-site waste remediation, point-of-use chemical synthesis, and heat-transfer. The material requirements for this application include chemical inertness and the ability to be fabricated into structures that contain internal features of complex geometries and small (<250 ?m) dimensions. It has been recognized that materials with limited formability, like ceramics and intermetallics, will be required for high temperature applications. Reactors from these materials have been produced from powder tapes. However, problems associated with binder removal and sintering result in dimensional instability of the internal geometry which degrades the performance of the reactor. In this paper, a method for forming an array of internal microchannels in a NiAl device that avoids the dimensional instability of powder processing is demonstrated. Microchannels are precision machined (via laser ablation) into elemental Ni and Al foils. During bonding, the foils are converted into NiAl. Results show that this is a viable method for producing aluminide-based structures containing complex, internal features.

Alman, D.E.; Wilson, R.D.; Dewey, T. (Oregon State Univ., Corvallis, OR); Paul, B.K. (Oregon State Univ., Corvallis, OR)

2000-07-01

298

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

299

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

NASA Technical Reports Server (NTRS)

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

Copland, Evan

2007-01-01

300

Homoepitaxial growth of AlN layers using by metalorganic vapor phase epitaxy on freestanding AlN substrate  

NASA Astrophysics Data System (ADS)

We fabricated the homoepitaxial AlN layers and AlGaN/AlN multi-quantum wells (MQWs) grown on freestanding AlN (0001) substrates by metalorganic vapor phase epitaxy. Crystallographic and optical characteristics of these AlN layers and AlGaN/AlN MQWs were investigated by X-ray diffraction (XRD), SEM, AFM, PL, and so on. These characteristics of MQWs are strongly dependent on growth condition of homoepitaxial AlN layer. In case that AlN layers are grown with high temperature and low V/III ratio, there are many hillocks on the surface and no PL signal from MQW. In contrast, strong PL emission cannot be obtained from AlGaN/AlN MQW on AlN layer grown with lower temperature and higher V/III ratio, because this MQW has large surface roughness from results of XRD and AFM measurement. We optimized the growth condition of AlN layers and obtained the high quality AlGaN/AlN MQW with smooth surface, strong PL emission.

Morishita, Tomohiro; Iwaya, Motoaki; Takeuchi, Tetsuya; Kamiyama, Satoshi; Akasaki, Isamu

2014-03-01

301

Potentiodynamic Polarization Aspects of the As-cast and Sprayed Al-Si, Al-Sn and Al-Sn-Si Alloys in a Sodium Chloride Solution  

NASA Astrophysics Data System (ADS)

The present study compares the corrosion behavior of Al-Sn, Al-Si and Al-Sn-Si alloys processed by spray forming with that of the conventional chill cast ones in aqueous 0.1 N NaCl solution. Spray forming resulted in finer microstructural features with uniform distribution of second-phase particles. The spray formed Al-Si samples showed improved corrosion resistance as compared to the chill cast ones. The Sn containing alloys showed inferior corrosion resistance in the neutral electrolyte. The addition of 12.5 wt.% Si to Al-Sn alloys improves the corrosion resistance.

Anil, M.; Balaji, S.; Upadhyaya, A.; Ghosh, M. K.; Ojha, S. N.

2010-12-01

302

On the structural development during ultrathin amorphous Al2O3 film growth on Al(111) and Al(100) surfaces by thermal oxidation  

NASA Astrophysics Data System (ADS)

The structural developments during growth of ultrathin amorphous Al2O3 film on bare Al(100) and Al(111) surfaces, by dry thermal oxidation in the oxygen partial pressure range of 1 × 10- 5-1.0 Pa at 300 K, were investigated as function of the oxide-film thickness by (local) chemical state analysis using angle-resolved X-ray photoelectron spectroscopy in combination with low electron energy diffraction and cross-sectional high resolution transmission electron microscopy. The effect of the dielectric discontinuity, at the interfaces of the surficial Al2O3 film has been determined quantitatively and has been subtracted from the observed chemical shifts of the core level photoelectron binding energies as well as from the observed Auger transition kinetic energies. It is revealed that ultrathin amorphous Al2O3 films on the Al(111) and Al(100) surfaces experience remarkably different structural developments upon growth.

Flötotto, D.; Wang, Z. M.; Mittemeijer, E. J.

2015-03-01

303

Thermal expansion of gehlenite, Ca2Al[AlSiO7], and the related aluminates LnCaAl[Al2O7] with Ln=Tb, Sm  

Microsoft Academic Search

The thermal expansion of gehlenite, Ca2Al[AlSiO7], (up to T=830 K), TbCaAl[Al2O7] (up to T=1,100 K) and SmCaAl[Al2O7] (up to T=1,024 K) has been determined. All compounds are of the melilite structure type with space group Pbar {4}2_1 m. Thermal expansion data was obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY)

L. Peters; K. Knorr; M. Knapp; W. Depmeier

2005-01-01

304

Intermediate temperature thermomechanical processing of Al 2090 for superplasticity  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

305

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

306

Study in the interfacial stability of Ti/Al2O3, Ti3Al/Al2O3 and TiAl/Al2O3 composite materials. Final report  

SciTech Connect

This thesis is a study of the interfacial stability of the Ti-Base metal matrix composites Ti/Al2O3, Ti3Al/Al2O3 and TiAl/Al2O3. Interfacial stability is discussed in view of the importance of thermodynamics and kinetics as the primary considerations which govern the type of stability observed. From a thermodynamics approach, the application of phase equilibrium diagrams is essential in the design of composite systems. A classification system, with reference to phase equilibrium, is used to describe the type of interfacial stability observed for the composites studied. In addition, electron-probe microanalysis, atom-probe field ion microscopy and X-ray diffraction results are used to establish Ti-Al-O phase relations for the temperature range 900-to-1250 deg C. The kinetics of interfacial stability is discussed with particular attention given to the kinetic considerations; diffusion path, phase formation sequence, steady-state layer growth and interface morphology. Kinetic results in the form of parabolic growth constants and calculated interdiffusion coefficients are presented.

DeKock, J.A.

1995-12-31

307

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

308

Influence of reaction with XeF2 on surface adhesion of Al and Al2O3 surfaces  

NASA Astrophysics Data System (ADS)

The change in surface adhesion after fluorination of Al and Al2O3 surfaces using XeF2 was investigated with atomic force microscopy. The chemical interaction between XeF2 and Al and Al2O3 surfaces was studied by in situ x-ray photoelectron spectroscopy. Fresh Al and Al2O3 surfaces were obtained by etching top silicon layers of Si /Al and Si /Al2O3 with XeF2. The surface adhesion and chemical composition were measured after the exposure to air or annealing (at 200°C under vacuum). The correlation between the adhesion force increase and presence of AlF3 on the surface was revealed.

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

2008-10-01

309

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

PubMed

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

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

2014-10-01

310

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

311

Fabrication of Al/Al3Ti Functionally Graded Materials by Reaction Centrifugal Mixed-Powder Method  

NASA Astrophysics Data System (ADS)

Formation of compositional gradient in Al/Al3Ti Functionally graded materials (FGMs) fabricated by the centrifugal method (CM) depends mainly on the centrifugal force and the processing temperature. In this study, a novel centrifugal method, reaction centrifugal mixed-powder method (RCMPM), was proposed to fabricate Al/Al3Ti FGMs under fixed centrifugal force (G=80). The effects of RCMPM processing temperature on the formation of Al3Ti intermetallics, its morphology and its distribution in the fabricated Al/Al3Ti FGMs have been investigated. Fine granular Al3Ti were observed at relatively lower processing temperature while the known coarse platelet-like particles of Al3Ti could be achieved at higher casting temperatures. Moreover, Ti3Al intermetallics compound and unreacted Ti phases are also observed along with Al3Ti particles. In addition, distribution of Al3Ti intermetallics size and their volume fraction showed a significant change when the Al/Al3Ti FGMs processed at different temperatures relative to the liquidus temperature of the master alloy.

El-Hadad, Shimaa; Sato, Hisashi; Miura-Fujiwara, Eri; Watanabe, Yoshimi

2011-01-01

312

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

313

Adaboost aplicado a clasificacin de fonemas Elkin Eduardo Garca Daz  

E-print Network

-máquina, siendo un campo importante de investigación por más de seis décadas [1]. Dentro de este campo de - Centro de Microelectrónica Universi- dad de los Andes análisis de los experimentos realizados a partir

Gao, Guang R.

314

Sensor de orvalho/chuva aplicado à operação de telescópios  

NASA Astrophysics Data System (ADS)

Foi desenvolvida uma estação meteorológica para o telescópio robótico Obelix do Observatório Abrahão de Moraes que inclui sensores de temperatura e umidade, além de um inédito sensor de orvalho e chuva que comanda o fechamento automático da cúpula caso haja perigo de condensação. Este sensor é composto de uma malha de segmentos metálicos próximos e detecta o aumento da condutividade do ar que precede a condensação. Esse método é mais confiável que o critério de 100% de umidade, que pode causar falsos alarmes devido a imprecisão dos sensores de umidade em geral e por não considerar a influência dos ventos que dificultam a condensação. O trabalho apresenta o método de construção desse sensor e os testes de avaliação. Sugere-se portanto a inclusão desse sensor nas estações meteorológicas dos telescópios do país.

Raffaelli, J. C.; Neres, N. L.; Strauss, C.

2003-08-01

315

Intereporabilidade Semântica, recuperação e mi- ning aplicado a documentos médicos  

Microsoft Academic Search

Resumo - Muitos são os componentes do histórico médico de um indivíduo. Estes componentes, em linha geral, são registrados das formas mais variadas e, normalmente, não são normalizados e\\/ou adequadamen- te armazenados (1), além de, em muitos casos, parte destes registros (Raio-X, prescrições,...) são extravia- dos ao longo do ciclo de vida do indivíduo. Ao longo da história das ciências

Edson José Pacheco; Percy Nohama

316

Método numérico aplicado a los modelos analógicos cuantificables (para polímeros)  

Microsoft Academic Search

La dynamique moléculaire des polymères peut s'expliquer en utilisant des systèmes construits avec des ressorts et des pistons. L'un des modèles les plus abordables est celiu de Vangheluwe et ses constantes paramétriques sont déterminées par les méthodes suivantes: méthode graphique, méthode itérative Marquardt, méthode de l'hyperplan. De même, un autre modèle important est celiu de Zurek qui détermine ses constantes

Ana María Islas Cortes; Gabriel Guillén Buendía; Manuel Olvera; Laura E. Mercado

1970-01-01

317

Revisiting the Al/Al2O3 Interface: Coherent Interfaces and Misfit Accommodation  

PubMed Central

We study the coherent and semi-coherent Al/?-Al2O3 interfaces using molecular dynamics simulations with a mixed, metallic-ionic atomistic model. For the coherent interfaces, both Al-terminated and O-terminated nonstoichiometric interfaces have been studied and their relative stability has been established. To understand the misfit accommodation at the semi-coherent interface, a 1-dimensional (1D) misfit dislocation model and a 2-dimensional (2D) dislocation network model have been studied. For the latter case, our analysis reveals an interface dislocation structure with a network of three sets of parallel dislocations, each with pure-edge character, giving rise to a pattern of coherent and stacking-fault-like regions at the interface. Structural relaxation at elevated temperatures leads to a further change of the dislocation pattern, which can be understood in terms of a competition between the stacking fault energy and the dislocation interaction energy at the interface. Our results are expected to serve as an input for the subsequent dislocation dynamics models to understand and predict the macroscopic mechanical behavior of Al/?-Al2O3 composite heterostructures. PMID:24670940

Pilania, Ghanshyam; Thijsse, Barend J.; Hoagland, Richard G.; Lazi?, Ivan; Valone, Steven M.; Liu, Xiang-Yang

2014-01-01

318

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

319

ALS 2883: Analysis of spectroscopic features  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

320

?-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. PMID:23762114

Yang, Eun Jin; Choi, Sun-Mi

2013-01-01

321

Transformation to Ni5Al3 in a 63.0 at. pct Ni-Al alloy  

NASA Technical Reports Server (NTRS)

Microstructures of 63 at. pct P/M Ni-Al alloys with a composition close to the stoichiometry of the Ni5Al3 phase were investigated using homogenized and quenched specimens aged at low temperatures for various times. Results of analyses of XRD data and electron microscopy observations were used for quantitative phase analysis, performed to calculate the (NiAl + Ni5Al3)/Ni5Al3 phase boundary locations. The measured lattice parameters of Ni5Al3 phase formed at 823, 873, and 923 K indicated an increase in tetragonality of the phase with increasing nickel content.

Khadkikar, P. S.; Locci, I. E.; Vedula, K.; Michal, G. M.

1993-01-01

322

Electron mobility enhancement in AlN/GaN/AlN heterostructures with InGaN nanogrooves  

E-print Network

in AlN/GaN/AlN heterostructures with the shallow InxGa1-xN channel--nanogroove--in the middle consider a narrow groove made of InxGa1-xN with small In content x inside a wurtzite AlN/GaN/AlN heteroN 3 nm /GaN 8 nm /AlN 3 nm QW and in QW with 2 nm wide nanogroove, i.e., AlN 3 nm /GaN 3 nm /InxGa1-xN

323

Phase equilibria in Al-rich Al-Mg-Sc-Zn alloys at 430 and 300°C  

NASA Astrophysics Data System (ADS)

Optical microscopy and X-ray diffraction and electron microprobe analyses are used to study Al-Mg-Sc-Zn alloys annealed at 430 and 300°C. The Al-based solid solution is found to be in equilibrium only with binary and ternary phases of the corresponding systems; these are Al3Sc, ?(Al3Mg2), ?(MgZn2), and ?(Al2Mg3Zn3). Sections are constructed for the isothermal tetrahedra of the Al-Mg-Sc-Zn phase diagram that correspond to a scandium content of 0.5% and magnesium and zinc contents of up to 20%.

Rokhlin, L. L.; Dobatkina, T. V.; Korol'Kova, I. G.

2008-02-01

324

Development of SiAlON materials  

NASA Technical Reports Server (NTRS)

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

Layden, G. K.

1977-01-01

325

The structure of extruded NiAl  

NASA Technical Reports Server (NTRS)

The deformation structure of Ni-rich NiAl extruded at 550 C has been characterized by transmission electron microscopy and by optical microscopy. Dislocations having a(100) Burgers vectors were found as complex networks, tangles, and prismatic loops. a(110) dislocations, which were rare, were concluded to arise from reactions of a(100) dislocations. Evidence of recovery and recrystallization was obtained. Extrusion was deemed to have been possible by the operation of (hko)(001) slip systems (often in plane strain flow) plus diffusion-assisted processes.

Baker, I.; Schulson, E. M.

1984-01-01

326

ALS insertion device block measurement and inspection  

SciTech Connect

The performance specifications for ALS insertion devices require detailed knowledge and strict control of the Nd-Fe-B permanent magnet blocks incorporated in these devices. This paper describes the measurement and inspection apparatus and the procedures designed to qualify and characterize these blocks. A detailed description of a new, automated Helmholtz coil facility for measurement of the three components of magnetic moment is included. Physical block inspection and magnetic moment measurement procedures are described. Together they provide a basis for qualifying blocks and for specifying placement of blocks within an insertion devices' magnetic structures. 1 ref., 4 figs.

Marks, S.; Carrieri, J.; Cook, C.; Hassenzahl, W.V.; Hoyer, E.; Plate, D.

1991-05-01

327

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2010-04-21

328

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

Federal Register 2010, 2011, 2012, 2013, 2014

...certain repurchase agreements. See Daily Money Fund, et al., Investment...23, 1993) (order), amending, Daily Money Fund, et al., Investment...the Funds in connection with their routine daily cash management activities and...

2012-11-13

329

Epitaxial Zintl aluminide SrAl4 grown on a LaAlO3 substrate  

NASA Astrophysics Data System (ADS)

Zintl phases are a class of intermetallic materials that have simultaneously ionic and covalent bonding resulting from charge transfer between two different atomic species. We present a combined first principles and experimental study of Zintl-phase SrAl4, which is grown in thin film form on the perovskite oxide LaAlO3 using molecular beam epitaxy. The structural properties are investigated using reflection-high-energy electron diffraction, x-ray diffraction, and cross-section transmission electron microscopy, which reveal relaxed epitaxial island growth. Photoelectron spectroscopy measurements verify the Zintl-Klemm nature of the bonding in the material and are utilized to determine the band offset and the work function of SrAl4, while transport measurements confirm its metallic behavior. The experimentally observed properties are confirmed using density functional calculations.

Schlipf, Lukas; Slepko, Alexander; Posadas, Agham B.; Seinige, Heidi; Dhamdhere, Ajit; Tsoi, Maxim; Smith, David J.; Demkov, Alexander A.

2013-07-01

330

Energy localization on the Al sublattice of Pt3Al with L12 order  

SciTech Connect

A three-dimensional molecular-dynamics model of with order was developed and found to support the excitation of discrete breathers (DBs) and energy localization on the Al sublattice. For an initial lattice temperature of 0 K, large-amplitude DBs polarized along [100] are found to be very weakly damped, retaining most of their initial energy for more than 2000 cycles, while DBs polarized along [111] damped out over ~30 cycles. Because the DBs and their dissipation channels are confined to the Al sublattice, long-lived nonequilibrium states with large energy differences between the Al and Pt sublattices occur. Since collisions during irradiation more efficiently generate lattice vibrations in light atoms than heavy atoms, such nonequilibrium states may occur and alter the relaxation processes occurring during radiation damage.

Medvedev, Nikolay N [Altay State Technical University, Russia] [Altay State Technical University, Russia; Starostenkov, Mikhail D [Altay State Technical University, Russia] [Altay State Technical University, Russia; Manley, Michael E [ORNL] [ORNL

2013-01-01

331

Reaction diffusion in the NiCrAl and CoCrAl systems  

NASA Technical Reports Server (NTRS)

The paper assesses the effect of overlay coating and substrate composition on the kinetics of coating depletion by interdiffusion. This is accomplished by examining the constitution, kinetics and activation energies for a series of diffusion couples primarily of the NiCrAl/Ni-10Cr or CoCrAl/Ni-10Cr type annealed at temperatures in the range 1000-1205 C for times up to 500 hr. A general procedure is developed for analyzing diffusion in multicomponent multiphase systems. It is shown that by introducing the concept of beta-source strength, which can be determined from appropriate phase diagrams, the Wagner solution for consumption of a second phase in a semiinfinite couple is successfully applied to the analysis of MCrAl couples. Thus, correlation of beta-recession rate constants with couple composition, total and diffusional activation energies, and interdiffusion coefficients are determined.

Levine, S. R.

1978-01-01

332

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

333

Transformation to Ni5Al3 in a 63.0 At. Pct Ni-Al alloy  

NASA Astrophysics Data System (ADS)

Microstructures in a 63 at. pct Ni-Al alloy, produced by a powder metallurgy process, have been investigated in detail in as-quenched and aged (823 to 923 K) conditions. The parent L10 martensite plus B2 NiAl microstructure in the as-quenched state transformed nearly completely to the orthorhombic Ni5Al3 phase upon aging at 823 K for 720 hours. The volume fraction of Ni5Al3 formed as a function of aging time at 823 K was observed to obey cellular reaction kinetic behavior. The specimens aged at 823 K for short times indicated that nucleation of the Ni5Al3 phase occurred preferentially at grain boundaries. Transmission electron microscopy (TEM) observations of short-time aged specimens revealed a complex microstructure consisting of shortrange ordered domains of Ni2Al in a matrix of 7R martensite, in addition to new variants of 3R martensite and Ni5Al3. Aging at 873 and 923 K for 720 hours produced a stable two-phase microstructure consisting of NiAl and Ni5Al3. A quantitative phase analysis was carried out to calculate the (NiAl + Ni5Al3)/Ni5Al3 phase boundary locations. The measured lattice parameters of Ni5Al3 formed at 823, 873, and 923 K indicated an increase in tetragonality of the phase with increasing nickel content.

Khadkikar, P. S.; Locci, I. E.; Vedula, K.; Michal, G. M.

1993-01-01

334

A Compliant and Creep Resistant SAC-Al(Ni) Alloy  

Microsoft Academic Search

Addition of Al into SAC alloys reduces the number of hard Ag3Sn and Cu6Sn5 IMC particles, and forms larger, softer non-stoichiometric AlAg and AlCu particles. This results in a significant reduction in yield strength, and also causes some moderate increase in creep rate. For high Ag SAC alloys, adding Al 0.1-0.6% to SAC alloys is most effective in softening, and

Benlih Huang; Hong-Sik Hwang; Ning-Cheng Lee

2007-01-01

335

Al-Nayrizi's Influence in the West Jan P. Hogendijk  

E-print Network

Al-Nayr¯iz¯i's Influence in the West Jan P. Hogendijk February 14, 2010 1 Introduction Ab¯u'l-c Abb¯as al-Fad.l ibn H. ¯atim al-Nayr¯iz¯i was a mathematician and as- tronomer who originated from the city of Nayr¯iz in Iran and who worked in Baghd¯ad.1 Since he wrote a treatise for Caliph al-Muc tad.id, who

Hogendijk, Jan P.

336

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

NASA Astrophysics Data System (ADS)

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

Tuck, C. D. S.

1985-08-01

337

Antiferromagnetism and magnetoleasticity of UNiAl  

NASA Astrophysics Data System (ADS)

We report on a thermal-expansion (TE) and magnetostriction (MS) study of the antiferromagnet UNiAl at temperatures 2- 90 K and in magnetic fields up to 16.5 T applied along the c-axis. The TE along the c-axis (in 0 T) exhibits a broad valley centered around 35 K. This anomaly is nearly removed in 16.5 T. For T?7 K a sharp metamagnetic transition (MT) observed in UNiAl at 11.4 T and it is accompanied by abrupt MS effects of +1.3×10 -4 and -1.8×10 -4 along the a- and c-axis, respectively. In fields above the MT a negligible additional negative MS is induced along c-axis whereas the a-axis and consequently the volume expand considerably, which indicates a field-induced enhancement of the U magnetic moment. T>7 K, the MT becomes gradually smeared out but a non-negligible MS is observed even for T> TN. In the light of these results the TE anomaly measured in zero field may be attributed to AF that survives at temperatures far above TN.

Sechovský, V.; Honda, F.; Svoboda, P.; Prokeš, K.; Chernyavsky, O.; Doerr, M.; Rotter, M.; Loewenhaupt, M.

2003-05-01

338

Design and performance of InAlGaAs\\/InAlAs superlattice avalanche photodiodes  

Microsoft Academic Search

InAlGaAs-InAlAs superlattice avalanche photodiodes (SL-APD's) have been designed and experimentally analyzed. The layer structures and the electric field profiles were designed for 10 Gb\\/s applications. The mesa-structure SL-APD's exhibited a gain-bandwidth product of 120-150 GHz, a top bandwidth of 15 GHz, and a multiplied dark current of 15-20 nA for a mesa-diameter of 30 ?m. Other characteristics, such as temperature

Isao Watanabe; Masayoshi Tsuji; Masako Hayashi; Kikuo Makita; Kenko Taguchi

1997-01-01

339

Inhomogeneous elastic deformation of nanofilms and nanowires of NiAl and FeAl alloys  

NASA Astrophysics Data System (ADS)

The molecular dynamics study of the uniaxial tension of nanofilms and nanowires of NiAl and FeAl intermetallide alloys has been performed. It has been shown that such samples are elastically deformed until failure at a strain of ? xx ? 0.35. There is an ? xx interval where the homogeneous deformation is thermodynamically unstable, leading to the formation of domains with different strains. The strain-stress dependence in the thermodynamically unstable region is almost linear, but has different slopes for a nanofilm and a nanowire because of the difference in the dynamics of domain walls.

Bukreeva, K. A.; Babicheva, R. I.; Dmitriev, S. V.; Zhou, K.; Mulyukov, R. R.

2013-09-01

340

Time-resolved photoluminescence studies of Al-rich AlGaN alloys  

NASA Astrophysics Data System (ADS)

Si-doped n-type AlxGa1MINxN alloys with x up to 0.5 and Mg-doped p-type AlxGa1-xN alloys with x up to 0.27 were grown by metal-organic chemical vapor deposition (MOCVD) on sapphire substrates. For the n-type AlxGa1-xN, we achieved highly conductive alloys for x up to 0.5. An electron concentration as high as 1x1018cm-3 was obtained in Si-doped Al0.5Ga0.5N alloys with an electron mobility of 16 cm_2)Vs at room temperature, as confirmed by Hall-effect measurements. Our results also revealed that the conductivity of AlxGa1-xN alloys continuously increases with an increase of Si doping level for a fixed value of Al content (X<0.5), the conductivities of AlxGa1-xN alloys decrease with increasing Al content for a given doping level; the critical Si-doping concentration needed to convert insulating AlxGa1-x)N with high Al contents (X>=0.4) to n- type conductivity is about 1 x 1018cm-3. Time- resolved photoluminescence studies carried out on these materials have shown that Si-doping reduces the effect of carrier localization in AlxGa1-xN alloys and a sharp drop in carrier localization energy occurs when the Si doping concentration increases above 1x1018cm-3, which directly correlates with the observed electrical properties. For the Mg-doped AlxGa1-xN alloys, p-type conduction was achieved for x up to 0.27, as confirmed by variable temperature Hall measurements. Emission lines of band-to-impurity transitions of free electrons with neutral Mg acceptors as well as localized excitons have been observed in the p-type AlxGa1-xN alloys. The Mg acceptor activation energies EA were deduces from photoluminescence spectra and were found to increase with Al content and agreed very well with those obtained by Hall measurements. From the measured activation energy as a function of Al content, EA versus x, the resistivity of Mg-doped AlxGa1-x with high Al contents can be deduced. Our results have also shown that PL measurements provide direct means of obtaining EA especially where this cannot be obtained accurately by electrical methods due to high resistance of p-type AlxGa1-xN with high Al content.

Li, Jing; Nam, Ki-Bum; Oder, Tom N.; Kim, KyoungHoon; Nakarmi, M. L.; Lin, Jing Y.; Jiang, Hongxing

2002-06-01

341

Characterization of Interface Charge in NbAlO/AlGaN/GaN MOSHEMT with Different NbAlO Thicknesses  

NASA Astrophysics Data System (ADS)

We investigate the influence of interface charge on electrical performance of NbAlO/AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs). Through C—V measurements and simulations, we find that the donor-type interface fixed charge density Qit of 2.2 × 1013 cm?2 exists at the NbAlO/AlGaN interface, which induces the shift of the threshold voltage much more negative. Furthermore, a trap density of approximately 0.43 × 1013–1.14 × 1013 cm?2eV?1 is obtained at the NaAlO/AlGaN interface, which is consistent with the frequency-dependent capacitance and conductance measurement results.

Feng, Qian; Du, Kai; Dai, Bo; Dong, Liang; Feng, Qing

2015-01-01

342

To Ponder Ponderal's Length: A Question to Lester et. al.  

ERIC Educational Resources Information Center

Criticizes Lester, Als, and Brazelton's 1982 reanalysis of data presented by Scanlon, Nelson, Grylack, and Smith in 1979. Discusses (1) clinical interpretation of the ponderal index (a weight-for-length ratio); and (2) inaccurate measurement of crown-heel length; (3) Lester et al.'s suggested relationship between the ponderal index, maternal drug,…

Scanlon, John W.

1984-01-01

343

Hybrid Silicon Integration R. Jones et al. Hybrid Silicon Integration  

E-print Network

Hybrid Silicon Integration R. Jones et al. 1 / 23 Hybrid Silicon Integration R. Jones1 , H. D. Park.jones@intel.com #12;Hybrid Silicon Integration R. Jones et al. 2 / 23 Hybrid Silicon Integration R. Jones1 , H. D.jones@intel.com Abstract: An overview is presented of the hybrid AlGaInAs-silicon platform that enables wafer level

Bowers, John

344

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

345

Constraining oceanic dust deposition using surface ocean dissolved Al  

E-print Network

Constraining oceanic dust deposition using surface ocean dissolved Al Qin Han,1 J. Keith Moore,1; accepted 7 December 2007; published 12 April 2008. [1] We use measurements of ocean surface dissolved Al (DEAD) model to constrain dust deposition to the oceans. Our Al database contains all available

Zender, Charles

346

Modelling Al and Mn in the open ocean  

E-print Network

Modelling Al and Mn in the open ocean Marco van Hulten*, Alessandro Tagliabue, Jean-Claude Dutay van Hulten: Modelling Al and Mn in the open ocean 1 #12;Outline Introduction Model of aluminium Constraining dust flux Model of manganese Conclusions Marco van Hulten: Modelling Al and Mn in the open ocean 2

Haak, Hein

347

782 A. Y. KAPLAN ET AL. SOFIA U. TARASOVA  

E-print Network

brain wave activities in real time and allow humans to use them for controlling any electronically addressable device or software through a local processor. In the late 1980s and early 1990s, the field of BCI deficit hyperactivity disorder in children (Linden et al., 1996; Lubar et al., 1997; Egner et al., 2001

Kaplan, Alexander

348

[Gerber et al (1989), Cancer 64, 2347-2353  

E-print Network

;nisms of this effect remain to be elucidated. [Moon et al (1992) Cancer Detect Prev 16, 73-79; Fontana et al ( I 992) Cancer Res 50, 1977-1982]. In the present study, we exam- ine the effect of all[Gerber et al (1989), Cancer 64, 2347-2353

Paris-Sud XI, Université de

349

Igor Kuznecov MOVPE von AlGaN-Schichten mit  

E-print Network

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

Nabben, Reinhard

350

Al2C monolayer: the planar tetracoordinate carbon global minimum  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

351

Effect of high intensity ultrasound on Al?Ni?, Al?Ni crystallite size in binary AlNi (50 wt% of Ni) alloy.  

PubMed

Crystallite size of the intermetallics is one of the most important parameters that can influence kinetics of catalytic reactions. Analysis of the crystallite sizes of Al?Ni and Al?Ni? intermetallic phases using Scherrer and Williamson-Hall methods reveals that the sonomechanical impact of ultrasound on suspensions of AlNi particles in ethanol results in crystallites growth and microstrain reduction. PMID:25171834

Cherepanov, Pavel V; Melnyk, Inga; Andreeva, Daria V

2015-03-01

352

Interdiffusion and intrinsic diffusion in the NiAl /delta/ phase of the Al-Ni system  

NASA Technical Reports Server (NTRS)

Interdiffusion coefficients at 950 to 1150 C and the ratio of intrinsic diffusion coefficients at 1100 C were measured as functions of composition in the NiAl (delta) phase of the Al-Ni system, using a vapor-solid technique. Diffusivity values were also obtained for the Ni3Al (epsilon) and Ni (Al) solid solution (zeta) phases from 950 to 1150 C. The interdiffusion coefficient in NiAl (delta) varies several orders of magnitude over the delta phase field with a deep minimum in the diffusivity-composition curve at 48 to 49 at% Al. The ratio of intrinsic diffusion coefficients DNi/DAl, in the delta phase also varies with composition from a value of 3 to 3.5 below 50 at% Al to 0.1 or less above 50 at% Al.

Shankar, S.; Seigle, L. L.

1978-01-01

353

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

354

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

355

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

356

AlGaN/GaN MIS-HEMT Gate Structure Improvement Using Al2O3 Deposited by PEALD  

E-print Network

AlGaN/GaN MIS-HEMT Gate Structure Improvement Using Al2O3 Deposited by PEALD R. Meunier1 , A, 38054 Grenoble Cedex 9, France 2 LAAS-CNRS, 7 Avenue du Colonel Roche, 31400 Toulouse, France AlGaN /GaN behavior. Those trapped charges can be associated to the carbon contamination of the AlGaN surface

Boyer, Edmond

357

Formation of nanocrystalline B2 NiAl through cryomilling of Ni50 at.%Al at 87 K  

Microsoft Academic Search

A wear-like mechanism occurs between balls and the entrapped nanocrystalline mixture of elemental Ni and Al powders resulting in the formation of B2 NiAl at the process temperature at 87 K during cryomilling. Nanocrystalline structure of B2 NiAl with average size of 6 nm was synthesized after 45 hours of milling. This B2 NiAl was found to be at nonstoichiometric

B.-L. Huang; J. Vallone; M. J. Luton

1995-01-01

358

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

E-print Network

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

Adams, James B

359

Isolation and characterization of a rice mutant hypersensitive to Al.  

PubMed

Rice (Oryza sativa L.) is a highly Al-resistant species among small grain crops, but the mechanism responsible for the high Al resistance has not been elucidated. In this study, rice mutants sensitive to Al were isolated from M(3) lines derived from an Al-resistant cultivar, Koshihikari, irradiated with gamma-rays. Relative root elongation was used as a parameter for evaluating Al resistance. After initial screening plus two rounds of confirmatory testing, a mutant (als1) was isolated from a total of 560 lines. This mutant showed a phenotype similar to the wild-type plant in the absence of Al. However, in the presence of 10 microM Al, root elongation was inhibited 70% in the mutant, but only 8% in the wild-type plant. The mutant also showed poorer root growth in acid soil. The Al content of root apices (0-1 cm) was much lower in the wild-type plant. The sensitivity to other metals including Cd and La did not differ between the mutant and the wild-type plants. A small amount of citrate was secreted from the roots of the mutant in response to Al stress, but there was no difference from that secreted by the wild-type plant. Genetic analysis of F(2) populations between als1 and wild-type plants showed that the Al-resistant seedlings and Al-sensitive seedlings segregated at a 3 : 1 ratio, indicating that the high sensitivity to Al in als1 is controlled by a single recessive gene. The gene was mapped to the long arm of chromosome 6, flanked by InDel markers MaOs0619 and MaOs0615. PMID:15857838

Ma, Jian Feng; Nagao, Sakiko; Huang, Chao Feng; Nishimura, Minoru

2005-07-01

360

Metallurgical Characteristics of TiAlN/AlCrN Coating Synthesized by the PVD Process on a Cutting Insert  

NASA Astrophysics Data System (ADS)

TiAlN/AlCrN coating was deposited on a tungsten carbide insert, using the plasma-enhanced physical vapor deposition (PEPVD) process. The microstructure of the coating was examined and it was found that the TiAlN/AlCrN coating was uniform, highly dense, and less porous. The different phases formed in the coating were analyzed using the x-ray diffraction. The hardness and scratch resistance were measured using the nanoindentation tester and scratch tester, respectively. TiAlN/AlCrN exhibited higher hardness, higher Young's modulus, and superior scratch resistance when compared to the conventional coatings, such as TiAlN, AlCrN, and TiN. The surface morphology of the coating was characterized using the atomic force microscope (AFM). The surface roughness was found to be lesser in the TiAlN/AlCrN coating. The TiAlN/AlCrN coating has proved to have better corrosion resistance, compared to the uncoated carbide substrate.

Sampath Kumar, T.; Balasivanandha Prabu, S.; Manivasagam, Geetha

2014-08-01

361

Growth of crack-free AlGaN film on thin AlN interlayer by MOCVD  

NASA Astrophysics Data System (ADS)

We have studied the effect of low-temperature-deposited (LT) and high-temperature-deposited (HT) AlN interlayer with various thickness on AlGaN film grown on GaN using c-plane sapphire as substrate. All the Al 0.25Ga 0.75N films thicker than 1 ?m with LT-AlN interlayer or with HT-AlN interlayer were free of cracks, however, their surfaces were different: the Al 0.25Ga 0.75N films with LT-AlN interlayer showed smooth surface, while those with HT-AlN interlayer exhibit rough surface morphology. The results of X-ray double crystal diffraction and Rutherford backscattering showed that all of the AlGaN films were under compressive strain in the parallel direction. The compressive strain resulted from the effect of interlayer-induced stress relieving and the thermal mismatch for the samples with LT-AlN interlayer, and it was due to the thermal mismatch between AlGaN and the underlying layers for those with HT-AlN interlayer.

Jin, R. Q.; Liu, J. P.; Zhang, J. C.; Yang, H.

2004-07-01

362

Oficina de Cooperacin al Desarrollo y Solidaridad (OCDS) La Oficina de Cooperacin al Desarrollo y Solidaridad (OCDS) se consolida, despus  

E-print Network

Oficina de Cooperación al Desarrollo y Solidaridad (OCDS) La Oficina de Cooperación al Desarrollo y Solidaridad (OCDS) se consolida, después de su creación en mayo de 2005 por acuerdo ejecutivo del Consejo de hacia la cooperación universitaria al desarrollo (CUD), la tarea hecha por el equipo de la OCDS y la

Oro, Daniel

363

Cryptanalysis of Cho et al.'s Protocol, A Hash-Based Mutual Authentication Protocol for RFID Systems  

E-print Network

Cryptanalysis of Cho et al.'s Protocol, A Hash-Based Mutual Authentication Protocol for RFID cryptanalysis a hash based RFID mutual authentication protocol which has been recently proposed by Cho et al impersonation attack: the success probability of attack is "1 4 " for two runs of protocol. Keywords: RFID

364

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] [Univ. of Western Australia, Nedlands (Australia). Research Centre for Advanced Mineral and Materials Processing

1995-02-01

365

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 400…

Polat, Soner; Oztoprak-Kavak, Zehra

2011-01-01

366

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

367

High Temperature Mechanical Characterization and Analysis of Al2O3 /Al2O3 Composition  

NASA Technical Reports Server (NTRS)

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

Gyekenyesi, John Z.; Jaskowiak, Martha H.

1999-01-01

368

Magnetic domain structure and anisotropy distribution in Al/Metglas 2605S2/Al trilayers  

NASA Astrophysics Data System (ADS)

Al coatings, with thickness (x) up to 20 µm, were deposited by dc sputtering on both sides of the Metglas 2605S2 precursor melt-spun ribbons. Spin reorientation, induced by the magnetoelastic effect, was clearly observed in the Al/Metglas 2605S2/Al trilayers by monitoring the 2 and 5 line intensities of the Mössbauer spectra obtained at different temperatures. The average spin orientation angles can be controlled by adjusting the Al thickness. A magneto-mechanical coefficient, which measures the rate of spin reorientation with respect to the temperature variation, was obtained and is found to be equal to -0.15° K-1 and -0.28° K-1 for x = 5 µm and 20 µm, respectively. Using a spin structure phenomenological model, in-plane native magnetic anisotropies ranging up to 3 kJ m-3 were estimated for the Metglas 2605S2 ribbons. Energy anisotropy values higher than 20 kJ m-3 are associated with inhomogeneities and defects from the sample preparation method and may correspond to about 10% of the ribbon volume.

Moscon, P. S.; Sánchez, F. H.; Passamani, E. C.; Larica, C.; Mendoza Zélis, P.

2008-11-01

369

High reflectivity ultraviolet distributed Bragg reflector based on AlGaN/AlGaN multilayer  

NASA Astrophysics Data System (ADS)

AlGaN/AlGaN distributed Bragg reflectors (DBRs) designed for the ultraviolet spectral region have been attained. The crack-free structures were grown on c-plane sapphire by plasma assisted molecular beam epitaxy (MBE). To minimize the built-in strain in DBRs, a thin buffer layer was used directly on c-plane sapphire. A peak reflectivity of 95% at 381 nm with a 21 nm stop band width was obtained at room temperature (RT) using a 32.5 pairs Al 0.7Ga 0.3N/Al 0.15Ga 0.85N DBR. With a driving force for DBRs and emitting regions in wide band gap semiconductor microcavities, such as those based on GaN and ZnO, is the quest for cavity polariton which is the coupled mode between the exciton and photon modes. Moreover, the exploitation of cavity polaritons could be expected in the course of the development of extremely low-threshold optoelectronics devices.

Shimada, Ryoko; Xie, Jinqiao; Morkoç, Hadis

2007-02-01

370

ESTUDIO DE LA RESISTENCIA AL DESGASTE DE RECUBRIMIENTOS DEPOSITADOS MEDIANTE PROYECCIÓN TÉRMICA SOBRE ACERO AL CARBONO  

Microsoft Academic Search

Coatings of Ni - Al, Ni - SiC, Ni -WC y Ni - W- Co, were deposited and its capacity to protect of the abrasive wear effects on the steel substrate where they were deposited was studied. Coatings were obtained by thermal spraying using oxygen - acetylene combustion gotten by an Eutalloy torch of the Eutectic Castolin trade mark. Materials

SERGIO ECHEVERRI; Estudiante Ingeniería; JULIANA BEDOYA; Estudiante Ingeniería de Materiales; FABIO VARGAS; Ingeniero Metalúrgico

2007-01-01

371

Structural, Optical, and Electrical Characterization of Al/ n-ZnO/ p-Si/Al Heterostructures  

NASA Astrophysics Data System (ADS)

For heterojunction fabrication, zinc oxide thin films were grown on p-Si by pulsed laser deposition. X-ray diffraction patterns were used to study the grain size and morphology of the films. The optical properties of the films were studied by UV-visible and photoluminescence spectroscopy. Experimental observations confirmed that the deposited films have potential for sharp emission in the visible region. High-purity (99.999%) vacuum evaporated aluminium metal was used to make contacts to the n-ZnO and p-Si. The current-voltage characteristics of the Al/ n-ZnO/ p-Si(100)/Al heterostructure measured over the temperature range 60-300 K were studied on the basis of the thermionic emission diffusion mechanism. The equivalent Schottky barrier height and the diode ideality factor were determined by fitting measured current-voltage data to the thermionic emission diffusion equation. It was observed that the barrier height decreased and the ideality factor increased with decreasing temperature, and that the activation energy plot was non-linear at low temperature. These characteristics are attributed to the Gaussian distribution of barrier heights. The capacitance-voltage characteristics of the Al/ n-ZnO/ p-Si(100)/Al heterostructure diode were studied over a wide temperature range. The impurity concentration in deposited n-type ZnO films was estimated from measured capacitance-voltage data.

Kumar, Rajender; Chand, Subhash

2015-01-01

372

X-Ray Videomicroscopy Studies of Eutectic Al-Si Solidification in Al-Si-Cu  

NASA Astrophysics Data System (ADS)

Al-Si eutectic growth has been studied in-situ for the first time using X-ray video microscopy during directional solidification (DS) in unmodified and Sr-modified Al-Si-Cu alloys. In the unmodified alloys, Si is found to grow predominantly with needle-like tip morphologies, leading a highly irregular progressing eutectic interface with subsequent nucleation and growth of Al from the Si surfaces. In the Sr-modified alloys, the eutectic reaction is strongly suppressed, occurring with low nucleation frequency at undercoolings in the range 10 K to 18 K. In order to transport Cu rejected at the eutectic front back into the melt, the modified eutectic colonies attain meso-scale interface perturbations that eventually evolve into equiaxed composite-structure cells. The eutectic front also attains short-range microscale interface perturbations consistent with the characteristics of a fibrous Si growth. Evidence was found in support of Si nucleation occurring on potent particles suspended in the melt. Yet, both with Sr-modified and unmodified alloys, Si precipitation alone was not sufficient to facilitate the eutectic reaction, which apparently required additional undercooling for Al to form at the Si-particle interfaces.

Mathiesen, R. H.; Arnberg, L.; Li, Y.; Meier, V.; Schaffer, P. L.; Snigireva, I.; Snigirev, A.; Dahle, A. K.

2011-01-01

373

First-principles calculations of Al dimer dynamics on Al(111)  

NASA Astrophysics Data System (ADS)

We study the dynamics of Al dimers on Al(111) using first-principles density-functional (DFT) calculations. The smooth potential energy surface ensures very low activation barriers for dimer rotation (<0.03 eV). This non-diffusive motion is confined by larger activation barriers for migration by concerted sliding (0.13 eV) and so-called inter-cell rotation (0.50 eV). The ground state is unexpectedly mixed, with the dimer atoms in neighboring fcc and hcp sites, and is enabled by a significant surface relaxation. A compressive strain (<= 5 %) effectively eliminates the already low rotation barriers, and establishes a new ground state consisting of a double bridge occupancy. The fcc-fcc and hcp-hcp configurations are rendered unstable, which has implications on the diffusive sliding motion. These effects lead us to discuss the possibility of a metal quantum rotor. The Al_2/Al(111) quantum rotor is in the end ruled out due to a strong coupling to the substrate, dominated by rather large elastic energies associated with the oscillations of certain underlying surface atoms. The many-body dissipation effects at various degrees of compression are studied with the effective-medium theory. Finally, dissociation of the dimer is shown to require as much as a 100% bond stretch.

Bogicevic, Alexander; Hyldgaard, Per; Lundqvist, Bengt I.

1998-03-01

374

Dynamic recrystallization in Al–Mg–Sc alloys  

Microsoft Academic Search

The main research interest was to investigate the mechanisms in the restoration process of Al–3mass% Mg and Al–3mass% Mg–0.2mass% Sc alloy containing second-phase Al3Sc precipitates. The alloy specimen, Al–3% Mg–0.2% Sc, was peak-aged, where it contained stable coherent, spherical Al3Sc precipitates with an average diameter of 0.2?m and a volume fraction of 0.005. The main techniques utilized are compression tests,

Kentaro Ihara; Yasuhiro Miura

2004-01-01

375

A novel hydride phase in hydrogen charged Ti3Al  

NASA Technical Reports Server (NTRS)

The effect of internal hydrogen on the microstructural modification of Ti3Al (alpha-2) compound was studied by large-angle neutron scattering and TEM. Ti-25 at. pct Al (Ti3Al) specimens were exposed to gaseous hydrogen atmosphere at 600 C that resulted in internal hydrogen concentration of 2000 ppm. The hydrogen-charged alloy consisted of a mixture of alpha-2 phase and a novel Ti3AlH phase with the E2(1), (Pm3m) crystal structure. The lattice parameters and atomic arrangement of the Ti3AlH phase were determined.

Schwartz, D. S.; Lederich, R. J.; Sastry, S. M. L.; Yelon, W. B.; Berliner, R. R.

1991-01-01

376

Ultraviolet laser diodes on sapphire and AlN substrates  

NASA Astrophysics Data System (ADS)

The performance characteristics of InAlGaN multiple quantum well (MQW) lasers grown on sapphire and low defect density bulk AlN substrates has been compared. The group III-nitride laser heterostructures were grown on (0001) AlN and c-plane sapphire substrates by metalorganic vapor phase epitaxy (MOVPE). Lasing was observed for optically pumped AlGaInN heterostructures in the wavelength range between 333 nm and 310 nm. A comparison of laser thresholds shows reduced threshold power densities for lasers grown on bulk AlN with threshold densities as low as 175 kW/cm2 for lasers emitting near 330 nm.

Kneissl, Michael; Yang, Zhihong; Teepe, Mark; Johnson, Noble M.

2009-02-01

377

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

PubMed

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

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

2012-02-28

378

Electron-ion recombination rate coefficients and photoionization cross-sections for Al XI, Al XII, Si XII, Si XIII for UV and X-ray modeling  

E-print Network

Electron-ion recombination rate coefficients and photoionization cross-sections for Al XI, Al XII-ion recombination UV and X-rays Al XI, Al XII, Si XII, Si XIII a b s t r a c t Results are presented from detailed study of inverse processes of photoionization and electron-ion recombination of (hm + Al XI Al XII + e

Nahar, Sultana Nurun

379

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

2013-01-01

380

Low alpha experiments at the ALS  

SciTech Connect

The authors present a modified, low alpha lattice for the Advanced Light Source where the quadrupole field strengths have been detuned to allow the momentum compaction factor to be varied smoothly from positive to negative values. With this low alpha lattice the authors decrease the momentum compaction factor by a factor of 5 to 0.0003 over normal operation resulting in a measured bunch length reduction of 2. They also measure the size the second order momentum compaction factor as well as store beam in a negative momentum compaction lattice. Streak camera measurements at positive and negative momentum compaction operation show longitudinal beam profile distributions that are in agreement with simulations by Fang et al.

Robin, D.; Alvis, R.; Jackson, A. [Lawrence Berkeley Lab., CA (United States); Holtzapple, R.; Podobedov, B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

1995-08-01

381

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

382

26Al uptake and accumulation in the rat brain  

NASA Astrophysics Data System (ADS)

To investigate the cause of Alzheimer's disease (senile dementia), 26Al incorporation in the rat brain was studied by accelerator mass spectrometry (AMS). When 26Al was injected into healthy rats, a considerable amount of 26Al entered the brain (cerebrum) through the blood-brain barrier 5 days after a single injection, and the brain 26Al level remained almost constant from 5 to 270 days. On the other hand, the level of 26Al in the blood decreased remarkably 75 days after injection. Approximately 89% of the 26Al taken in by the brain cell nuclei bound to chromatin. This study supports the theory that Alzheimer's disease is caused by irreversible accumulation of aluminium (Al) in the brain, and brain cell nuclei.

Yumoto, S.; Nagai, H.; Imamura, M.; Matsuzaki, H.; Hayashi, K.; Masuda, A.; Kumazawa, H.; Ohashi, H.; Kobayashi, K.

1997-03-01

383

Overview of the development of FeAl intermetallic alloys  

SciTech Connect

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

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

1995-09-01

384

Targeting autophagy in ALS: a complex mission.  

PubMed

Several neurodegenerative diseases share a common neuropathology, primarily featuring the presence of abnormal protein inclusions in the brain containing specific misfolded proteins. Strategies to decrease the load of protein aggregates and oligomers are considered relevant targets for therapeutic intervention. Many studies indicate that macroautophagy is a selective and efficient mechanism for the degradation of misfolded mutant proteins related to neurodegeneration, without affecting the levels of the corresponding wild-type form. In fact, activation of autophagy by rapamycin treatment decreases the accumulation of protein aggregates and alleviates disease features in animal models of Huntington disease and other disorders affecting the nervous system. Recent evidence, however, indicates that the expression of several disease-related genes may actually impair autophagy activity at different levels, including omegasome formation, substrate recognition, lysosomal acidity and autophagosome membrane nucleation. A recent report from Zhang and co-workers indicates that treatment of an amyotrophic lateral sclerosis (ALS) mouse model with rapamycin actually exacerbates neuronal loss and disease progression, associated with enhanced apoptosis. This study reflects the need for a better understanding of the contribution of autophagy to ALS and other neurodegenerative diseases since this pathway may not only operate as a cleaning-up mechanism. Then, autophagy impairment may be part of the pathological mechanisms underlying the disease, whereas augmenting autophagy levels above a certain threshold could lead to detrimental effects in neuronal function and survival. Combinatorial strategies to repair the autophagy deficit and also enhance the activation of the pathway may result in a beneficial impact to decrease the content of protein aggregates and damaged organelles, improving neuronal function and survival. PMID:21252621

Nassif, Melissa; Hetz, Claudio

2011-04-01

385

Comparison of the transport properties of high quality AlGaN/AlN/GaN and AlInN/AlN/GaN two-dimensional electron gas heterostructures  

NASA Astrophysics Data System (ADS)

The transport properties of high mobility AlGaN/AlN/GaN and high sheet electron density AlInN/AlN/GaN two-dimensional electron gas (2DEG) heterostructures were studied. The samples were grown by metal-organic chemical vapor deposition on c-plane sapphire substrates. The room temperature electron mobility was measured as 1700 cm2/V s along with 8.44×1012 cm-2 electron density, which resulted in a two-dimensional sheet resistance of 435 ?/? for the Al0.2Ga0.8N/AlN/GaN heterostructure. The sample designed with an Al0.88In0.12N barrier exhibited very high sheet electron density of 4.23×1013 cm-2 with a corresponding electron mobility of 812 cm2/V s at room temperature. A record two-dimensional sheet resistance of 182 ?/? was obtained in the respective sample. In order to understand the observed transport properties, various scattering mechanisms such as acoustic and optical phonons, interface roughness, and alloy disordering were included in the theoretical model that was applied to the temperature dependent mobility data. It was found that the interface roughness scattering in turn reduces the room temperature mobility of the Al0.88In0.12N/AlN/GaN heterostructure. The observed high 2DEG density was attributed to the larger polarization fields that exist in the sample with an Al0.88In0.12N barrier layer. From these analyses, it can be argued that the AlInN/AlN/GaN high electron mobility transistors (HEMTs), after further optimization of the growth and design parameters, could show better transistor performance compared to AlGaN/AlN/GaN based HEMTs.

Tülek, Remziye; Ilgaz, Aykut; Gökden, Sibel; Teke, Ali; Öztürk, Mustafa K.; Kasap, Mehmet; Özçelik, Süleyman; Arslan, Engin; Özbay, Ekmel

2009-01-01

386

Tropical soils cultivated with tomato: fractionation and speciation of Al.  

PubMed

Soil acidity and the associated problems of aluminum (Al) toxicity and scarce exchangeable bases are typically the most important limiting factors of agricultural yield in wet tropical regions. The goals of this study were to test how soil lime rates affect the forms and distribution of Al in the soil fractions and how different levels of bioavailable Al affect two tomato genotypes grown in wet tropical soils. The tomato genotypes CNPH 0082 and Calabash Rouge were grown in two wet tropical soils in a greenhouse. Soil lime rates of 0, 560, and 2240 mg kg(-1) soil (clay soil) and 0, 280, and 1120 mg kg(-1) soil (sandy soil) were applied to modify Al concentrations. Dry mass production and Al concentrations were determined in shoots and roots. Al was fractionated in the soil, and the soil solution was speciated after cultivation. The Calabash Rouge genotype possesses mechanisms to tolerate Al(3+), absorbed less Al, exhibited smaller reduction in growth, and lower Al concentrations in plant parts than the CNPH 0082. Increased soil pH reduced the exchangeable Al fraction and increased the fraction mainly linked to organic matter. Al in the soil in the form of complexes with organic compounds and Al(SO4)(+) (at the highest lime rate) did not affect plant development. Soil acidity can be easily neutralized by liming the soil, which transforms toxic Al(3+) in the soil into forms that do not harm tomato plants, thereby avoiding oxidative stress in the plants. Al-induced stress in tomatoes varies with genotypes and soil type. PMID:25740686

Nogueirol, Roberta Corrêa; Monteiro, Francisco Antonio; Azevedo, Ricardo Antunes

2015-04-01

387

Electronic Structures of CeNi 2Al 5 and CeNiAl 4 Studied by Photoelectron Spectroscopy  

NASA Astrophysics Data System (ADS)

We have studied the electronic structures of ternary intermetallic compounds CeNi2Al5 and CeNiAl4 on the basis of Ce 3d core level spectra by X-ray photoelectron spectroscopy and high resolution Ce 4d?4f resonant photoemission spectra. In the 4f photoemission spectra, fine structures near the Fermi edge manifest that hybridization strength is considerably larger in CeNiAl4 than in CeNi2Al5. The electronic structures of these compounds are discussed in connection with those of Ce Ni and Ce Al intermetallic compounds.

Kashiwakura, Takayuki; Okane, Tetsuo; Suzuki, Shoji; Sato, Shigeru; Watanabe, Masamitsu; Harasawa, Ayumi; Kinoshita, Toyohiko; Kakizaki, Akito; Ishii, Takehiko; Nakai, Shun-ichi; Isikawa, Yosikazu

2000-09-01

388

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

E-print Network

on their structural and electronic properties. Our results, based on density functional calculations, reveal-coordinated Al sites. I. Introduction Aluminum oxide, Al2O3, traditionally referred to as alumina, is a very+ and O2- ions whose electrostatic interactions are primarily responsible for alumina's cohesive energy

Pandey, Ravi

389

Interface/border trap characterization of Al2O3/AlN/GaN metal-oxide-semiconductor structures with an AlN interfacial layer  

NASA Astrophysics Data System (ADS)

We report the interface characterization of Al2O3/AlN/GaN MOS (metal-oxide-semiconductor) structures with an AlN interfacial layer. A thin monocrystal-like interfacial layer (AlN) is formed at the Al2O3/GaN to effectively block oxygen from the GaN surface and prevent the formation of detrimental Ga-O bonds. The suppression of Ga-O bonds is validated by X-ray photoelectron spectroscopy of the critical interface. Frequency-dispersion in C-V characteristics has been significantly reduced, owing to improved interface quality. Furthermore, using the conventional conductance method suitable for extracting the interface trap density Dit in MOS structures, Dit in the device with AlN was determined to be in the range of 1011-1012 eV-1 cm-2, showing one order of magnitude lower than that without AlN. Border traps near the gate-dielectric/GaN interface were identified and shown to be suppressed by the AlN interfacial layer as well.

Liu, Shenghou; Yang, Shu; Tang, Zhikai; Jiang, Qimeng; Liu, Cheng; Wang, Maojun; Shen, Bo; Chen, Kevin J.

2015-02-01

390

Enhanced spectral response of an AlGaN-based solar-blind ultraviolet photodetector with Al nanoparticles.  

PubMed

An enhanced spectral response was realized in an AlGaN-based solar-blind ultraviolet (SB-UV) detector using aluminum (Al) nanoparticles (NPs) of 20-60 nm. The peak responsivity of the detector (about 288 nm) with 60 nm Al NPs is more than two times greater than that of a detector without Al NPs under a 5-V bias, reaching 0.288 A/W. To confirm the enhancement mechanism of the Al NPs, extinction spectra were simulated using time-domain and frequency-domain finite-element methods. The calculation results show that the dipole surface plasmon resonance wavelength of the Al NPs is localized near the peak responsivity position of AlGaN-based SB-UV detectors. Thus, the improvement in the detectors can be ascribed to the localized surface plasmon resonance effect of the Al NPs. The localized electric field enhancement and related scattering effect result in the generation of more electron-hole pairs and thus a higher responsivity. In addition, the dark current of AlGaN-based SB-UV detectors does not increase after the deposition of Al nanoparticles. The results presented here is promising for applications of AlGaN-based SB-UV detectors. PMID:25322003

Bao, Guanghong; Li, Dabing; Sun, Xiaojuan; Jiang, Mingming; Li, Zhiming; Song, Hang; Jiang, Hong; Chen, Yiren; Miao, Guoqing; Zhang, Zhiwei

2014-10-01

391

Molecular and phenotypic characterization of Als1 and Als2 mutations conferring tolerance to acetolactate synthase herbicides in soybean  

PubMed Central

BACKGROUND Sulfonylurea (SU) herbicides are effective because they inhibit acetolactate synthase (ALS), a key enzyme in branched-chain amino acid synthesis required for plant growth. A soybean line known as W4-4 was developed through rounds of seed mutagenesis and was demonstrated to have a high degree of ALS-based resistance to both post-emergence and pre-emergence applications of a variety of SU herbicides. This report describes the molecular and phenotypic characterization of the Als1 and Als2 mutations that confer herbicide resistance to SUs and other ALS inhibitors. RESULTS The mutations are shown to occur in two different ALS genes that reside on different chromosomes: Als1 (P178S) on chromosome 4 and Als2 (W560L) on chromosome 6 (P197S and W574L in Arabidopsis thaliana). CONCLUSION Although the Als1 and Als2 genes are unlinked, the combination of these two mutations is synergistic for improved tolerance of soybeans to ALS-inhibiting herbicides. © 2014 DuPont Pioneer. Pest Management Science published by JohnWiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:24425499

Walter, Kay L; Strachan, Stephen D; Ferry, Nancy M; Albert, Henrik H; Castle, Linda A; Sebastian, Scott A

2014-01-01

392

Ion-beam mixing and thermal annealing of Al--Nb and Al--Ta thin films  

SciTech Connect

Ion-beam mixing and thermal annealing of thin, alternating layers of Al and Nb, as well as Al and Ta, were investigated by selected area diffraction and Rutherford backscattering. The individual layer thicknesses were adjusted to obtain the overall compositions as Al/sub 3/Nb and Al/sub 3/Ta. The films were ion mixed with 1 MeV Au/sup +/ ions at a dose of 1 x 10/sup 16/ ions cm/sup -2/ . Uniform mixing and amorphization were achieved for both Al--Nb and Al--Ta systems. Equilibrium crystalline Al/sub 3/Nb and Al/sub 3/Ta phases were formed after annealing of ion mixed amorphous films at 400 /sup 0/C for 6 h. Unmixed films, however, remained unreacted at 400 /sup 0/C for 1 h. Partial reaction was observed in the unmixed film of Al--Nb at 400 /sup 0/C for 6 h. After annealing at 500 /sup 0/C for 1 h, a complete reaction and formation of Al/sub 3/Nb and Al/sub 3/Ta phases in the respective films were observed. The influence of thermodynamics on the phase formation by ion mixing and thermal annealing is discussed.

Rai, A.K.; Bhattacharya, R.S.; Mendiratta, M.G.; Subramanian, P.R.; Dimiduk, D.M.

1988-11-01

393

Al-26 and O-16 in the early solar system - Clues from meteoritic Al2O3  

SciTech Connect

The study focuses on 26 Al2O3 grains up to 20 micron in size recovered from the Murchison C2 chrondite. It is observed that Mg-26/Mg-24 ranges up to 56 times the solar system ratio, but the initial Al-26/Al-27 ratios do not exceed the canonical maximum of 0.00005 in other meteoritic samples. It is concluded that this ratio represents the abundance of live Al-26 in the early solar system, not fossil radiogenic Mg-26 surviving from presolar times. The grains are shown to divide into three groups on the basis of Al-26, O-16, Ti, and V content, and distinctive correlations are found for Al-26 and O-16. An origin from at least three discrete components is suggested, two of which contained live Al-26. 24 refs.

Anders, E.; Lewis, R.S.; Virag, A.; Zinner, E. (Chicago, Univ., IL (USA) Washington Univ., Saint Louis, MO (USA))

1991-06-01

394

Al-26 and O-16 in the early solar system - Clues from meteoritic Al2O3  

NASA Technical Reports Server (NTRS)

The study focuses on 26 Al2O3 grains up to 20 micron in size recovered from the Murchison C2 chrondite. It is observed that Mg-26/Mg-24 ranges up to 56 times the solar system ratio, but the initial Al-26/Al-27 ratios do not exceed the canonical maximum of 0.00005 in other meteoritic samples. It is concluded that this ratio represents the abundance of live Al-26 in the early solar system, not fossil radiogenic Mg-26 surviving from presolar times. The grains are shown to divide into three groups on the basis of Al-26, O-16, Ti, and V content, and distinctive correlations are found for Al-26 and O-16. An origin from at least three discrete components is suggested, two of which contained live Al-26.

Anders, Edward; Lewis, Roy S.; Virag, Alois; Zinner, Ernst

1991-01-01

395

High quality semipolar (11{sup ¯}02) AlGaN/AlN quantum wells with remarkably enhanced optical transition probabilities  

SciTech Connect

Adjusting the growth conditions from those for c-plane growth realizes high-quality semipolar (11{sup ¯}02) AlGaN/AlN quantum wells (QWs) with atomically smooth surfaces and abrupt interfaces on AlN substrates. Upon comparing the optical properties to those of c-plane QWs using time-integrated and time-resolved photoluminescence spectroscopy, the estimated internal electric field is much smaller in (11{sup ¯}02) AlGaN/AlN QWs than in c-plane QWs. Thus, (11{sup ¯}02) AlGaN/AlN QWs have narrower emission line widths and remarkably faster radiative recombination lifetimes, realizing highly efficient deep ultraviolet emissions.

Ichikawa, S., E-mail: shuhei.ichikawa@optomater.kuee.kyoto-u.ac.jp; Iwata, Y.; Funato, M.; Kawakami, Y., E-mail: kawakami@kuee.kyoto-u.ac.jp [Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510 (Japan); Nagata, S. [JFE Mineral Co. Ltd., Chiba 260-0826 (Japan)

2014-06-23

396

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

397

Improvement of the Electrochemical Behavior of Steel Surfaces Using a [Ti-Al/Ti-Al-N] n Multilayer System  

NASA Astrophysics Data System (ADS)

The aim of this work is to improve the corrosion resistance of AISI D3 steel surfaces using a [Ti-Al/Ti-Al-N] n multilayer system deposited with different periods (?) and bilayer numbers ( n), via magnetron co-sputtering pulsed d.c. procedure, from a metallic (Ti-Al) binary target. The multilayer coatings were characterized by cross-sectional scanning electron microscopy that showed the modulation and microstructure of the [Ti-Al/Ti-Al-N] n multilayer system. The composition of the single Ti-Al and Ti-Al-N layer films was studied via x-ray photoelectron spectroscopy, where typical signals for Ti2p1/2, Ti2p, N1s, and Al2p3/2 were detected. The electrochemical properties were evaluated by electrochemical impedance spectroscopy and Tafel polarization curves. The optimal electrochemical behavior was obtained for the [Ti-Al/Ti-Al-N] n multilayered period of ? = 25 nm (100 bilayers). At these conditions, the maximum polarization resistance (1719.32 k? cm2) and corrosion rate (0.7 ?my) were 300 and 35 times higher than that of uncoated AISI D3 steel substrate (5.61 k? cm2 and 25 ?my, respectively). Finally, scanning electron microscopy was used to analyze the [Ti-Al/Ti-Al-N] n multilayered surface after the corrosive attack. The improvement effects in the electrochemical behavior of the AISI D3 coated with the [Ti-Al/Ti-Al-N] n multilayered coatings could be attributed to the number of interfaces that act as obstacles for the inward and outward diffusions of Cl- ions, generating an increment in the energy or potential required for translating the corrosive ions across the coating/substrate interface.

Ipaz, L.; Aperador, W.; Caicedo, J. C.; Esteve, J.; Zambrano, G.

2013-05-01

398

Shock induced reaction of Ni/Al nanopowder mixture.  

PubMed

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

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

2012-11-01

399

Inverse Thermal Analysis of Heat-Affected Zone in Al2129 and Al2198 Laser Welds  

NASA Astrophysics Data System (ADS)

Case study analyses of A12139 and Al2198 laser welds are presented. These analyses demonstrate the concept of constructing parameter spaces for prediction of properties within the heat-affected zone (HAZ) of welds using inverse modeling, which are in turn for process control. The construction of these parameter spaces consists of two procedures. One procedure entails calculation of a parameterized set of temperature histories by inverse analysis of the heat deposition occurring during welding. The other procedure entails correlating these temperature histories with a specific physical property of the weld that is measurable. The analyses presented here examines some characteristics of inverse modeling with respect to the prediction of hardness within the HAZ for deep penetration laser welding of the Aluminum alloys A12139 and Al2198. This study further demonstrates the feasibility of constructing a parameter space for the prediction of weld properties using weld cross section measurements that are independent of weld process conditions.

Zervaki, A. D.; Haidemenopoulos, G. N.; Lambrakos, S. G.

2013-06-01

400

High Performance Polarized Electron Photocathodes Based on InGaAlAs/AlGaAs Superlattices  

NASA Astrophysics Data System (ADS)

Highly efficient emitters of polarized electrons based on the InAlGaAs/AlGaAs superlattice give an optimistic prognosis to explorations of such structures as the sources for accelerators. A new set of these SL structures with minimized conduction band offset was designed and recently tested. A new technology of surface protection in MBE growth leads to a significantly reduced heat-cleaning temperature. At these lowered cleaning temperatures, the thermal degradation of the working structure parameters is avoided. As a result a polarization P of up to 91% at corresponding quantum efficiency (QE) of 0.3% was achieved at room temperature. A 50% increase in the photocathode lifetime has been achieved with Sb coverage.

Mamaev, Y. A.; Subashiev, A. V.; Yashin, Y. P.; Gerchikov, L. G.; Luh, D.; Maruyama, T.; Clendenin, J. E.; Ustinov, V. M.; Zhukov, A. E.

2005-08-01

401

Chemical shielding properties for BN, BP, AlN, and AlP nanocones: DFT studies  

NASA Astrophysics Data System (ADS)

The properties of boron nitride (BN), boron phosphide (BP), aluminum nitride (AlN), and aluminum phosphide (AlP) nanocones were investigated by density functional theory (DFT) calculations. The investigated structures were optimized and chemical shielding (CS) properties including isotropic and anisotropic CS parameters were calculated for the atoms of the optimized structures. The magnitudes of CS parameters were observed to be mainly dependent on the bond lengths of considered atoms. The results indicated that the atoms could be divided into atomic layers due to the similarities of their CS properties for the atoms of each layer. The trend means that the atoms of each layer detect almost similar electronic environments. Moreover, the atoms at the apex and mouth of nanocones exhibit different properties with respect to the other atomic layers.

Mirzaei, Mahmoud; Yousefi, Mohammad; Meskinfam, Masoumeh

2012-06-01

402

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

SciTech Connect

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

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

1992-01-01

403

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

SciTech Connect

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

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

1992-12-01

404

Josephson effect in Al/Bi2Se3/Al coplanar hybrid devices  

NASA Astrophysics Data System (ADS)

The edge states of Topological Insulators (TI) are protected against backscattering, thanks to the topological properties arising from their band structure. Coupling a TI to a superconductor (S) can induce unconventional effects, including the creation of Majorana bound states (MBS). The fabrication of coplanar hybrid devices is a fundamental step to pave the way to the understanding of proximity effects in topologically non-trivial systems, and to a large variety of experiments aimed at the possible detection of MBS. We discuss the feasibility and some relevant properties of Al-Bi2Se3-Al coplanar proximity devices. Special attention is devoted to the design of the junction, aimed at enhancing the coupling between the electrodes and the TI.

Galletti, L.; Charpentier, S.; Lucignano, P.; Massarotti, D.; Arpaia, R.; Tafuri, F.; Bauch, T.; Suzuki, Y.; Tagliacozzo, A.; Kadowaki, K.; Lombardi, F.

2014-08-01

405

Near-infrared OPO in an AlGaAs/AlOx waveguide  

NASA Astrophysics Data System (ADS)

Within the ambitious quest for an electrically pumped version of the optical parametric oscillator (OPO), we demonstrate the first near-infrared integrated OPO in a direct gap semiconductor. This nonlinear device is based on a selectively oxidized GaAs/AlAs heterostructure, the same "AlOx" technology that is at the heart of VCSEL fabrication. The heterostructure and waveguide design allows for type-I form-birefringent phase matching, with a TM00 pump around 1 ?m and TE00 signal and idler around 2 ?m. Relying on the high non-resonant ?(2) of GaAs, relatively weak guided-wave optical losses, and monolithic SiO2/TiO2 dichroic Bragg mirrors, we observe a threshold of 210 mW at degeneracy in the continuous-wave regime, with a single-pass-pump doubly resonant scheme. Further improvement can be achieved by adopting a double-pump-pass scheme and, in a more fundamental way, by further optimizing the waveguide optical losses. The latter are induced by a not entirely mastered AlAs oxidation process and are of two distinct types: Rayleighlike scattering at signal and idler wavelength (? <= 1cm-1), due to the interface roughness between GaAs and AlOx layers; and absorption at pump wavelengths (? ? 3cm-1), due to volume defects in the GaAs layers adjacent to the aluminum oxide. This result marks a milestone for integrated nonlinear photonics and represents a significant step toward the goal of a broadly tunable coherent light source on chip.

Ozanam, C.; Savanier, M.; Lanco, L.; Lafosse, X.; Andronico, A.; Favero, I.; Ducci, S.; Leo, G.

2013-12-01

406

AlGaN/AlN-GaN-SL HEMTs with Multiple 2DEG Channels  

NASA Astrophysics Data System (ADS)

We report on a multichannel approach for AlGaN/GaN high-electron-mobility transistors (HEMTs) to increase the carrier mobility in the low and high sheet carrier concentration regimes. Between the AlGaN barrier and GaN buffer, alternating thin layers of AlN and GaN were inserted to create multiple two-dimensional electron gas (2DEG) channels. All samples were grown by metalorganic vapor-phase epitaxy (MOVPE) on sapphire substrates and compared with conventional single-channel HEMT with the same sheet carrier concentration. For low total 2DEG carrier concentrations (<8 × 1012 cm-2), the mobility for the multichannel HEMT was enhanced due to a reduction of ionized impurity and dislocation scattering, which originates from a backbarrier effect of the underlying AlN layers. In the high total carrier concentration regime (>8 × 1012 cm-2), a mobility improvement is attributed to distribution of the sheet charge into multiple 2DEG channels. This has been found to reduce the carrier concentration per individual channel, which leads to larger distance between 2DEG and heterointerfaces and therefore less impact of interface roughness and alloy scattering. With increasing number of channels, phonon scattering is also reduced due to lowering of the three-dimensional (3D) electron density, which results from the added volume of the multiple 2DEGs. With this approach, the HEMT mobility was increased from 1620 cm2 V-1 s-1 to 1960 cm2 V-1 s-1 for a triple-channel device at sheet carrier concentration of 7.5 × 1012 cm-2.

Wille, Ada; Yacoub, Hady; Debald, Arne; Kalisch, Holger; Vescan, Andrei

2014-11-01

407

Effects of Al ion implantation on the strength of Al 2O 3 particles  

Microsoft Academic Search

Ion implantation into ceramic materials changes their mechanical properties. These changes are also affected by the substrate, however. To examine the effect of ion implantation without the effect of the substrate, in this study ?-Alumina particles (average diameter of 2 ?m) were implanted with 2.6 MeV Al ions at an ion dose of 1×1017 cm?2. The implantation introduced the defect, such as vacancies

Hisato Ogiso; Mikiko Yoshida; Shizuka Nakano; Jun Akedo

2007-01-01

408

Angels in Islam: a commentary with selected translations of Jal?l al-D?n al-Suy???’s Al-?ab?’ik f? akhb?r almal?’ik (The Arrangement of the Traditions about Angels)   

E-print Network

This thesis presents a commentary with selected translations of Jal?l al-D?n cAbd al- Ra?m?n al-Suy???’s Al-?ab?’ik f? akhb?r al-mal?’ik (The Arrangement of the Traditions about Angels). The work is a collection of around ...

Burge, Stephen Russell

2010-01-01

409

Diffusion in single crystal of melilite: interdiffusion of Al + Al vs. Mg + Si  

NASA Astrophysics Data System (ADS)

Interdiffusion coefficients of Al + Al vs. Mg + Si in the gehlenite-åkermanite system of melilite were determined by coupled annealing of synthesized end-member single crystals. The observed diffusion coefficients for a couple-annealed sample vary for about 2 orders of magnitude, showing strong dependence on the gehlenite-åkermanite composition: diffusion coefficient observed at 1350 °C, for example, is 3 × 10-13 cm2 s-1 at 5 mol% åkermanite composition (Ak5), increases to 2 × 10-11 cm2 s-1 at Ak80, and then decreases to 1 × 10-12 cm2 s-1 at Ak95. The diffusion coefficient-temperature relation indicates high activation energy of diffusion of about 420 kJ mol-1 for gehlenite-rich melilite. The observed diffusion coefficient-composition relation may be explained by a combination of (1) the diffusion coefficient-melting temperature relation (Flynn's rule) and (2) the feasibility of local charge compensation, which can possibly be maintained more easily in the intermediate chemical composition. The high activation energy value for gehlenitic melilite appears to correspond to the complex diffusion mechanism. The observed highly variable diffusion coefficients suggest that gehlenite-åkermanite zoning in the melilite crystals in Ca, Al-rich inclusions in the carbonaceous meteorites may provide a sensitive indicator for the thermal history of the inclusions.

Nagasawa, H.; Suzuki, T.; Ito, M.; Morioka, M.

410

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

SciTech Connect

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

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

1997-02-01

411

Impact of SiO2 on Al–Al thermocompression wafer bonding  

NASA Astrophysics Data System (ADS)

Al–Al thermocompression bonding suitable for wafer level sealing of MEMS devices has been investigated. This paper presents a comparison of thermocompression bonding of Al films deposited on Si with and without a thermal oxide (SiO2 film). Laminates of diameter 150?mm containing device sealing frames of width 200?µm were realized. The wafers were bonded by applying a bond force of 36 or 60?kN at bonding temperatures ranging from 300–550?°C for bonding times of 15, 30 or 60?min. The effects of these process variations on the quality of the bonded laminates have been studied. The bond quality was estimated by measurements of dicing yield, tensile strength, amount of cohesive fracture in Si and interfacial characterization. The mean bond strength of the tested structures ranged from 18–61?MPa. The laminates with an SiO2 film had higher dicing yield and bond strength than the laminates without SiO2 for a 400?°C bonding temperature. The bond strength increased with increasing bonding temperature and bond force. The laminates bonded for 30 and 60?min at 400?°C and 60?kN had similar bond strength and amount of cohesive fracture in the bulk silicon, while the laminates bonded for 15?min had significantly lower bond strength and amount of cohesive fracture in the bulk silicon.

Malik, Nishant; Schjølberg-Henriksen, Kari; Poppe, Erik U.; Taklo, Maaike M. V.; Finstad, Terje G.

2015-03-01

412

Ferromagnetism in UCo1-xMnxAl and UCo1-xVxAl  

NASA Astrophysics Data System (ADS)

UCoAl is an itinerant 5 f-electron metamagnet with a tiny critical field of transition B c?0.4 T (at 1.3 K). Critical magnetic parameters of this material are strongly sensitive to chemical environment of U atoms. We present results of a pilot study of formation, crystal structure and magnetism of UCo1-xTxAl compounds for T=Mn and V, x?0.1. All these compounds have been found to be isostructural with the parent compound. Already for x=0.01 in both systems a spontaneous magnetization M s has been observed at low temperatures. Anomalies in the AC susceptibility as a function of temperature point to T c?28 and 25 K respectively for Mn and V doping. The ferromagnetism induced in UCo1-xTxAl compounds due to a substitution of light transition metal for Co is discussed within a model considering effects of varying 5 f-ligand hybridization on the stability of U 5 f-moment and on exchange interactions.

Izmaylov, M.; Rafaja, D.; Sechovský, V.; Andreev, A. V.

2002-01-01

413

3DGRAPE/AL User's Manual  

NASA Technical Reports Server (NTRS)

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

Sorenson, Reese L.; Alter, Stephen J.

1995-01-01

414

[Visiting nurse for a terminal ALS patient].  

PubMed

The authors' hospital is a 585-bed hospital under the direct management of the National Health Insurance System. The hospital has been providing visiting nurses for the past 8 years, who work from local medical centers and the Visiting Nurses Department. Thirty-seven patients have received such home care, among whom 8 had intractable disease. Patient S was a 46-year-old woman who suffered from amyotrophic lateral sclerosis (ALS). The onset of the disease was in April, 1993, when the patient experienced muscular atrophy in both legs and deteriorating muscular strength. The diagnosis was definitive in 1995. On March 1, 1998, the patient received emergency hospitalization for breathing difficulties and aspiration pneumonia, and on March 5 underwent tracheotomy. A cannula had to be inserted for tubal feeding, and the physician in charge explained to her family that her prognosis was 3 months. Both the patient and her family desired home care, and the patient returned home on April 11. Respecting the wishes of the patient, the visiting nurse provided support so that home treatment could be continued. In the end, the patient lived at home while receiving home treatment for 7 months. Through the support provided by the visiting nurse, efforts were made to keep the patient's condition stable, and she was able to continue home treatment and living at home for a higher quality of life. PMID:10630215

Kitamikado, H; Sugihara, S; Enomoto, K; Sueda, M; Tanaka, T; Mori, H; Fukuyama, Y

1999-12-01

415

ALS liquid hydrogen turbopump: Advanced Development Program  

NASA Technical Reports Server (NTRS)

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

Shimp, Nancy R.; Claffy, George J.

1989-01-01

416

A deep atmospheric eclipse of AL Velorum  

NASA Technical Reports Server (NTRS)

I have obtained new International Ultraviolet Explorer (IUE) observations in 1992 to search for an accretion column in and to analyze an atmospheric eclipse of AL Vel, a low luminosity zeta Aurigae binary. Rich shell spectra recorded at three phases of atmospheric eclipse give column densities and excitation temperatures for the chromospheric gas. The chromospheric density falls off exponentially with a scale height of 3 solar radius, an order of magnitude greater than expected for support by thermal motions. Excitation temperatures at 2 - 5 scale heights into the chromosphere are approximately 7000 K, with Doppler widths near 17 km/s. Absorption features that could be formed in an accretion column were detected at phases 0.70 and 0.75 in a series of spectra spanning the range 0.63-0.80 in orbital phase. They imply a very slow acceleration of the wind, consistent with results for other zeta Aur binaries, but the wind speed implied is inconsistent with profiles of wind lines. The terminal velocity of this wind, greater than or approximately = 360 km/s, is higher than that in any of the other zeta Aur binaries. Wind and chromospheric features in 1992 were much more prominent than in 1988, which implies that both the wind and chromosphere were much more massive: we seem to have witnessed in 1992 a burst of activity with a mass-loss rate greater than 10(exp -8) solar mass/yr.

Eaton, Joel A.

1994-01-01

417

Roll Casting of Al-25%Si  

SciTech Connect

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

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

2011-05-04

418

Roll Casting of Al-25%Si  

NASA Astrophysics Data System (ADS)

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

Haga, Toshio; Harada, Hideto; Watari, Hisaki

2011-05-01

419

Reactive codoping of GaAlInP compound semiconductors  

DOEpatents

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

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

2008-02-12

420

Cost-Effective TiAl based Materials  

NASA Technical Reports Server (NTRS)

Because of their inherent low ductility, TiAl-based materials are difficult to fabricate, especially thin gage titanium gamma aluminide (TiAl) sheet and foil. In this paper, an innovative powder metallurgy approach for producing cost-effective thin gage TiAl sheets (with 356 mm long and 235 mm wide, and a thickness of 0.74, 1.09, 1.55, and 2.34 mm, respectively) is presented. The microstructures and tensile properties at room and elevated temperatures of the thin gage TiAl are studied. Results show that these TiAl sheets have a relatively homogenous chemistry, uniform microstructure, and acceptable mechanical properties. This work demonstrates a cost-effective method for producing both flat products (sheet/foil) and complex chunky parts of TiAl for various advanced applications including aerospace and automotive industries.

Moxson, V. S.; Sun, Fusheng; Draper, Susan L.; Froes, F. H.; Duz, V.

2003-01-01

421

Al environment in tectosilicate and peraluminous glasses: A 27Al MQ-MAS NMR, Raman, and XANES investigation  

NASA Astrophysics Data System (ADS)

Tecto-aluminosilicate and peraluminous glasses have been prepared by conventional and laser heating techniques, respectively, in the CaO-Al 2O 3-SiO 2 system. The structure of these glasses were studied using Raman spectroscopy, X-ray absorption at the Al K-edge and 27Al NMR spectroscopy with two different high fields (400 and 750 MHz). Raman spectroscopy and X-ray absorption are techniques sensitive to the network polymerization and, in particular, show different signal as a function of silica content. However, these two techniques are less sensitive than NMR to describe the local aluminium environment. For tectosilicate glasses, aluminium in five-fold coordination, [5]Al, was found and a careful quantification allows the determination of a significant amount of [5]Al (7% in the anorthite glass). The proportion of [5]Al increases for the peraluminous glasses with small amounts (<2%) of six-fold coordination, [6]Al. The presence of [5]Al agrees with previous observations of the existence of nonbridging oxygens (NBOs) in tectosilicate compositions. However, the proportion of [5]Al in the present study indicates that no major proportion of triclusters (oxygen coordinated to three (Si,Al)O 4 tetrahedra) is required to explain these NBOS.

Neuville, Daniel R.; Cormier, Laurent; Massiot, Dominique

2004-12-01

422

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

423

Preparation of Al-Cr-Fe Coatings by Heat Treatment of Electrodeposited Cr/Al Composite Coatings  

NASA Astrophysics Data System (ADS)

Al-Cr-Fe coatings have been widely used in the surface engineering field of materials, due to their excellent corrosion resistance to water vapor and fused salt deposits. In this study, a new two-step approach was developed to prepare Al-Cr-Fe coatings on surfaces of SUS430 stainless steels. First, the Cr/Al composite coatings were prepared by electrodepositing Cr from aqueous solution then electrodepositing Al from AlCl3-1-ethyl-3-methyl-imidazolium chloride (AlCl3-EMIC) ionic liquid on SUS430 stainless steel substrate. In the second, heat treatment of the Cr/Al composite coatings was carried out to acquire Al-Cr-Fe coatings. Effects of the thickness of Cr/Al composite coatings, the time and temperature of heat treatment on composition and phase structure of alloy layers were studied by using scanning electron microscope (SEM), backscattered electron (BSE), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The structure transformation process and formation mechanism of Al-Cr-Fe coatings were discussed.

Zhang, Min; Chen, Chang'an; Zhang, Guikai; Rao, Yongchu; Ling, Guoping

424

Probing the Structure and Bonding in Al6N- and Al6N by Photoelectron Spectroscopy and Ab Initio Calculations  

SciTech Connect

The electronic and geometrical structure of a nitrogen-doped Al6 - cluster (Al6N-) is investigated using photoelectron spectroscopy and ab initio calculations. Photoelectron spectra of Al6N- have been obtained at three photon energies with seven resolved spectral features. The electron affinity of Al6N has been determined to be 2.58 (0.04 eV. Global minimum structure searches for A6N- and its corresponding neutral form are performed using several theoretical methods. Vertical electron detachment energies, calculated using three different methods for the lowest energy structure and a low-lying isomer, are compared with the experimental data. The ground-state structure of Al6N- is established from the joint experimental and theoretical study to consist of an Al2 dimer bonded to the top of a quasi-planar tetracoordinated N unit, Al4N-, or it can be viewed as a distorted trigonal prism structure with the N atom bonded in one of the prism faces. For neutral Al6N, three low-lying isomers are found to compete for the global minimum, two of which are built from the tetracoordinated Al4N unit. The chemical bonding in Al6N- is discussed on the basis of molecular orbital and natural bond analyses.

Averkiev, Boris B.; Boldyrev, Alexander I.; Li, Xi; Wang, Lai S.

2007-01-11

425

Effect of transition metal additives on electronic structure and elastic properties of TiAl and Ti3Al  

NASA Astrophysics Data System (ADS)

We have studied the correlation between the electronic structure and elastic properties of ?-TiAl (space group P4/mmm , prototype AuCu) as well as ?2-Ti3Al (space group P63/mmc , prototype Ni3Sn ) alloyed with VB (V, Nb, Ta), VIB (Cr, Mo, W), and VIIB (Mn) transition metals, using ab initio calculations. Upon alloying, the bulk modulus is increased as compared to unalloyed phases. This can be understood based on the partial density of states analysis. The bonding in ?-TiAl and ?2-Ti3Al is mainly metallic, due to Ti d-Ti d interactions, and there is a weak covalent contribution, due to hybridization between Al p and Ti d orbitals. This increase in the bulk modulus is due to band filling. On the other hand, the values of the elastic constant C44 are comparable with or lower than those of ?-TiAl and ?2-Ti3Al . Upon alloying, the metallic bonding character is enhanced and the covalent bonding character is reduced. The bulk-modulus-to- C44 ratio is hence larger as compared to the unalloyed substances. The largest value is obtained for the Mn substitution, resulting in a 13.5% and 19.6% increase for ?-TiAl and ?2-Ti3Al , respectively. These results are of relevance to the tailoring of the mechanical properties of TiAl alloys.

Music, Denis; Schneider, Jochen M.

2006-11-01

426

93Nb- and 27Al-NMR/NQR studies of the praseodymium based PrNb2Al20  

NASA Astrophysics Data System (ADS)

We report a study of 93Nb- and 27Al-nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) in a praseodymium based compound PrNb2Al20. The observed NMR line at around 3 T and 30 K shows a superposition of typical powder patterns of one Nb signal and at least two Al signals. 93Nb-NMR line could be reproduced by using the previously reported NQR frequency ?Q ? 1.8MHz and asymmetry parameter ? ? 0 [Kubo T et al 2014 JPS Conf. Proc. 3 012031]. From 27Al-NMR/NQR, NQR parameters are obtained to be ?Q,A ? 1.53 MHz, and ?A ? 0.20 for the site A, and ?Q,B ? 2.28 MHz, and ?B ? 0.17 for the site B. By comparing this result with the previous 27Al-NMR study of PrT2Al20 (T = Ti, V) [Tokunaga Y et al 2013 Phys. Rev. B 88 085124], these two Al site are assigned to the two of three crystallographycally inequivalent Al sites.

Kubo, Tetsuro; Kotegawa, Hisashi; Tou, Hideki; Higashinaka, Ryuji; Nakama, Akihiro; Aoki, Yuji; Sato, Hideyuki

2015-03-01

427

Defect analysis in AlGaN layers on AlN templates obtained by epitaxial lateral overgrowth  

NASA Astrophysics Data System (ADS)

The defect distribution in thick AlN layers obtained by epitaxial lateral overgrowth (ELO-AlN) has been analyzed as a function of the miscut direction of the patterned sapphire substrate. A 0.25° miscut toward the sapphire a-plane leads to formation of smooth ELO-AlN layers containing vertical coalescence grain boundaries and exhibiting an almost homogeneous threading dislocation (TD) distribution with a TD density ranging from 5×108 cm-2 to 8×108 cm-2. In contrast, a 0.25° miscut toward the sapphire m-plane results in formation of periodically arranged macrosteps on the surface of the coalesced ELO-AlN layers as well as formation of inclined coalescence grain boundaries leading to an inhomogeneous TD distribution. A subsequent AlxGa1-xN deposition onto ELO-AlN template with surface macrosteps leads to Ga enrichment on the step sidewalls and, for lower Al-contents (e.g. x=0.5), even to additional defect formation. For higher Al contents (e.g. x=0.8) no additional threading dislocations are formed in the AlGaN layers and the observed TD density corresponds to that of the ELO-AlN template: less than 108 cm-2 in the wing regions and from 6×108 cm-2 to 9×108 cm-2 above the ridges. Compressive strain during growth of Al0.8Ga0.2N on ELO-AlN tends to be compensated by threading dislocation inclination. However, due to the low TD densities the inclination angles are more than 3 times larger than those observed in Al0.8Ga0.2N layers on planar AlN/sapphire templates.

Mogilatenko, Anna; Küller, Viola; Knauer, Arne; Jeschke, J.; Zeimer, Ute; Weyers, Markus; Tränkle, Günther

2014-09-01

428

Hard boride coating on iron aluminide (FeAl)  

Microsoft Academic Search

The mechanical properties of borided iron aluminide (FeAl) were investigated. Boronizing was carried out in a solid medium consisting of Ekabor powders at 940 °C for 2, 4 and 8 h. The formation of FeB on the surface of FeAl was confirmed by XRD analysis. Metallographic studies revealed an almost saw-tooth-like and compact boride layer on the FeAl. The thickness of boride

Erdinç Ekmekçiler; Aytekin Polat; Metin Usta

2008-01-01

429

CuAlSe_2 Thin Films Obtained by Chalcogenization  

Microsoft Academic Search

CuAlSe2 thin films have been synthesized by chalcogenization of thin Cu and Al layers sequentially deposited by evaporation under vacuum. It is shown that CuAlSe2 films are obtained with some Cu{2-delta}Se2 and Se phases present at the surface. These surface phases are suppressed by annealing under vacuum and by chemical etching in a KCN solution. At the end of the

S. Marsillac; K. Benchouk; C. El Moctar; J. C. Bernède; J. Pouzet; A. Khellil; M. Jamali

1997-01-01

430

Terahertz detection by GaN=AlGaN transistors  

E-print Network

Terahertz detection by GaN=AlGaN transistors A. El Fatimy, S. Boubanga Tombet, F. Teppe, W. Knap, D mobility GaN=AlGaN transistors in the 0.2­2.5 THz frequency range (much higher than the cutoff frequency of operation remains a challenge to achieve. Since GaN=AlGaN heterostructure FETs (HFETs) have extremely high

Pala, Nezih

431

Evidence for association between Ir and Al in L chondrites.  

NASA Technical Reports Server (NTRS)

The nature of the Al-Ir association was investigated by plotting the whole chondrite abundance of Ir as determined by Mueller et al. (1971), and the Al abundance for the same chondrites. Ten of the 11 L chondrites plotted show a definite positive trend. The results are most consistent with the condensation mechanism of Larimer (1967) and the prediction of Larimer and Anders (1970).

Osborn, T. W.

1972-01-01

432

Radiation Hard AlGaN Detectors and Imager  

SciTech Connect

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

None

2012-05-01

433

Electronic structure and transport properties of Fe–Al alloys  

Microsoft Academic Search

Electronic structure of iron-aluminides (Fe1?xAlx) has been calculated for a range of aluminum concentration (0?x?0.5) by using first principles density functional theory to explain the variation of electrical resistivity with increasing Al content. The Fe–Al intermetallics are modeled by a cluster of 15 atoms confined to their bulk geometry. The location of Al atoms as a function of concentration, x

B. V. Reddy; P. Jena; S. C. Deevi

2000-01-01

434

Optical characterization of AlN\\/GaN heterostructures  

Microsoft Academic Search

AlN\\/GaN\\/sapphire heterostructures with AlN gate film thickness of 3-35 nm are characterized using photoreflectivity (PR) and photoluminescence (PL) spectroscopy. Under a critical AlN film thickness, the luminescence from the GaN channel layer near the interface proves to be excitonic. No luminescence related to the recombination of the two-dimensional electron gas (2DEG) is observed, in spite of high 2DEG parameters indicated

V. V. Ursaki; I. M. Tiginyanu; V. V. Zalamai; S. M. Hubbard; D. Pavlidis

2003-01-01

435

Overview of the development of FeAl intermetallic alloys  

Microsoft Academic Search

B2-phase FeAl ordered intermetallic alloys based on an Fe-36 at.% Al composition are being developed to optimize a combination of properties that includes high-temperature strength, room-temperature ductility, and weldability. Microalloying with boron and proper processing are very important for FeAl properties optimization. These alloys also have the good to outstanding resistance to oxidation, sulfidation, and corrosion in molten salts or

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

1995-01-01

436

Der Heidelberger Kulturhistoriker Richard Benz als Deuter der Romantik  

Microsoft Academic Search

Der Heidelberger Kulturhistoriker Richard Benz (1884–1966) beschäftigte sich zeitlebens jenseits des akademischen Betriebs\\u000a als freier Schriftsteller, Publizist und Vortragsredner mit deutscher Literatur-, Kunst- und Musikgeschichte vor allem der\\u000a Epoche um 1800.1 Er betrachtete sich dabei als Vertreter einer romantischen Geisteshaltung und verband sein Schaffen explizit mit dem genius loci Heidelbergs als Erinnerungsort der Romantik.2 Einer der engsten Freunde von Richard

Julia Scialpi

437

Spectra of surface plasmon polariton enhanced electroluminescence from electroformed Al-Al2O3-Ag diodes  

NASA Astrophysics Data System (ADS)

Narrow band-pass filters have been used to measure the spectral distribution of electroluminescent photons with energies between 1.8 eV and 3.0 eV from electroformed Al-Al2O3-Ag diodes with anodic Al2O3 thicknesses between 12 nm and 18 nm. Electroforming of metal-insulator-metal (MIM) diodes is a non-destructive dielectric breakdown that results in a conducting channel in the insulator and changes the initial high resistance of the MIM diode to a low resistance state. It is a critical step in the development of resistive-switching memories that utilize MIM diodes as the active element. Electroforming of Al-Al2O3-Ag diodes in vacuum results in voltage-controlled negative resistance (VCNR) in the current-voltage (I-V) characteristics. Electroluminescence (EL) and electron emission into vacuum (EM) develop simultaneously with the current increase that results in VCNR in the I-V characteristics. EL is due to recombination of electrons injected at the Al-Al2O3 interface with radiative defect centers in Al2O3. Measurements of EL photons between 1.8 eV and 3.0 eV using a wide band-pass filter showed that EL intensity is exponentially dependent on Al2O3 thickness for Al-Al2O3-Ag diodes between 12 nm and 20 nm thick. Enhanced El intensity in the thinnest diodes is attributed to an increase in the spontaneous emission rate of recombination centers due to high electromagnetic fields generated in Al2O3 when EL photons interact with electrons in Ag or Al to form surface plasmon polaritons at the Al2O3-Ag or Al2O3-Al interface. El intensity is a maximum at 2.0-2.2 eV for Al-Al2O3-Ag diodes with Al2O3 thicknesses between 12 nm and 18 nm. EL in diodes with 12 nm or 14 nm of Al2O3 is enhanced by factors of 8-10 over EL from a diode with 18 nm of Al2O3. The extent of EL enhancement in the thinnest diodes can vary significantly between samples. A narrow band of recombination centers was found in one Al-Al2O3-Ag diode with 12 nm of Al2O3; it had EL intensity 100 times greater at 2.15 eV than the diode with 18 nm of Al2O3. EL intensity for photons with energies greater than 2.6 eV is nearly the same for all diodes.

Hickmott, T. W.

2015-03-01

438

High breakdown voltage in AlGaN/GaN HEMTs using AlGaN/GaN/AlGaN quantum-well electron-blocking layers.  

PubMed

In this paper, we numerically study an enhancement of breakdown voltage in AlGaN/GaN high-electron-mobility transistors (HEMTs) by using the AlGaN/GaN/AlGaN quantum-well (QW) electron-blocking layer (EBL) structure. This concept is based on the superior confinement of two-dimensional electron gases (2-DEGs) provided by the QW EBL, resulting in a significant improvement of breakdown voltage and a remarkable suppression of spilling electrons. The electron mobility of 2-DEG is hence enhanced as well. The dependence of thickness and composition of QW EBL on the device breakdown is also evaluated and discussed. PMID:25206318

Lee, Ya-Ju; Yao, Yung-Chi; Huang, Chun-Ying; Lin, Tai-Yuan; Cheng, Li-Lien; Liu, Ching-Yun; Wang, Mei-Tan; Hwang, Jung-Min

2014-01-01

439

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

NASA Technical Reports Server (NTRS)

The intermetallic compounds Beta-NiAl, FeAl, and CoAl were tested in cyclic oxidation with selected third element alloy additions. Tests in static air for 200 1-hr cycles at 1200 C indicated by specific weight change/time data and x-ray diffraction analysis that the 5 at percent alloy additions did not significantly improve the oxidation resistance over the alumina forming baseline alloys without the additions. Many of the alloy additions were actually deleterious. Ta and Nb were the only alloy additions that actually altered the nature of the oxide(s) formed and still maintained the oxidation resistance of the protective alumina scale.

Barrett, C. A.; Titran, R. H.

1992-01-01

440

Precipitation in Two Al-Mg-Ge Alloys  

Microsoft Academic Search

Two Al-Mg-Ge alloys with compositions Al-0.87Mg-0.43Ge (at. pct) and Al-0.59Mg-0.71Ge (at. pct) were investigated and compared\\u000a using high-resolution transmission electron microscopy, annular dark-field scanning transmission electron microscopy, and\\u000a nano-beam electron diffraction. The alloys contained fine needle- and lath-shaped precipitates after aging at 473 K (200 °C)\\u000a for 16 hours, which produced hardnesses similar to those measured in comparable Al-Mg-Si alloys. The ?? phase was not

R. Bjørge; C. D. Marioara; S. J. Andersen; R. Holmestad

2010-01-01

441

Precipitation in Two Al-Mg-Ge Alloys  

Microsoft Academic Search

Two Al-Mg-Ge alloys with compositions Al-0.87Mg-0.43Ge (at. pct) and Al-0.59Mg-0.71Ge (at. pct) were investigated and compared using high-resolution transmission electron microscopy, annular dark-field scanning transmission electron microscopy, and nano-beam electron diffraction. The alloys contained fine needle- and lath-shaped precipitates after aging at 473 K (200 °C) for 16 hours, which produced hardnesses similar to those measured in comparable Al-Mg-Si alloys.

R. Bjørge; C. D. Marioara; S. J. Andersen; R. Holmestad

2010-01-01

442

Ground-state electric quadrupole moment of Al31  

NASA Astrophysics Data System (ADS)

The ground-state electric quadrupole moment of Al31(I?=5/2+,T1/2=644(25)ms) has been measured by means of ?-ray-detected nuclear magnetic resonance spectroscopy using a spin-polarized Al31 beam produced in the projectile fragmentation reaction. The obtained Q moment, |Qexp(Al31)|=112(32)emb, is in agreement with conventional shell model calculations within the sd valence space. Previous results on the magnetic moment also support the validity of the sd model in this isotope, and thus it is concluded that Al31 is located outside of the island of inversion.

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.; Kawamura, H.; Narita, K.; Murata, J.

2009-02-01

443

Enhanced dehalogenation of halogenated methanes by bimetallic Cu/Al.  

PubMed

A low-cost and high effective copper/aluminum (Cu/Al) bimetal has been developed for treatments of halogenated methanes, including dichloromethane, in near neutral and high pH aqueous systems. Bimetallic Cu/Al was prepared by a simple two-step synthetic method where Cu was deposited onto the Al surface. The presence of Cu on Al significantly enhanced rates of degradation of halogenated methanes and reduced toxic halogenated intermediates. The stability of Cu/Al was preliminarily studied by a multi-spiking batch experiment where complete degradation of carbon tetrachloride was achieved for seven times although the Cu/Al aging was found. Roles of Cu may involve protecting Al against an undesirable oxidation with water, enhancing reaction rates through the galvanic corrosion, and increasing the selectivity to a benign compound (i.e., methane). Kinetic analyses indicated that the activity of bimetallic Cu/Al was comparable to that of iron-based bimetals (e.g., palladized iron) and zero-valent metals. Bimetallic Cu/Al could be a promising reactive reagent for remediation of halogenated solvents-contaminated groundwater associated with high pH problems. PMID:12365834

Lien, Hsing-Lung; Zhang, Weixian

2002-10-01

444

al-Qaida Strategy, Ideology, Doctrine, and Media  

ScienceCinema

Dr. Jarret Brachman, an internationally recognized al-Qaida specialist, author and public lecturer, shares his thoughts on a range of topics, including the differences involved in fighting insurgent groups versus terrorist organizations, the future of the global al-Qaida movement, and assessing America's efforts to combat al-Qaida. In his talk, Brachman focuses specifically on current trends in al-Qaida's military and messaging strategies, both from the perspective of the group's senior leadership and its regional commands. Presented on June 17, 2010.

Dr. Jarret Brachman

2010-09-01

445

Design of quaternary Ir-Nb-Ni-Al refractory superalloys  

Microsoft Academic Search

We propose a method for developing new quaternary Ir-Nb-Ni-Al refractory superalloys for ultra-high-temperature uses, by mixing\\u000a two types of binary alloys, Ir-20 at. pct Nb and Ni-16.8 at. pct Al, which contain fcc\\/L12 two-phase coherent structures. For alloys of various Ir-Nb\\/Ni-Al compositions, we analyzed the microstructure and measured\\u000a the compressive strengths. Phase analysis indicated that three-phase equilibria—fcc, Ir3Nb-L12, and Ni3Al-L12—existed

X. H. Yu; Y. Yamabe-Mitarai; Y. Ro; H. Harada

2000-01-01

446

Al?C monolayer: the planar tetracoordinate carbon global minimum.  

PubMed

Inspired by our theoretical finding that C?Al?(2-) has a planar D?h minimum with two planar tetracoordinate carbons (ptCs), we computationally designed a new two-dimensional (2D) inorganic material, an Al?C monolayer. All carbons in this monolayer are ptC's, stabilized inductively by binding to four electropositive Al atoms in the same plane. The Al?C monolayer is semiconducting with an indirect minimum band gap and a slightly larger direct band gap. Good persistence of the Al?C monolayer is indicated by its moderate cohesive energy, the absence of imaginary modes in its phonon spectrum, and the high melting point predicted by molecular dynamics (MD) simulations. Moreover, a particle-swarm optimization (PSO) global minimum search found the Al?C monolayer to be the lowest-energy 2D structure compared to other Al?C alternatives. Dividing the Al?C monolayer results in one-dimensional (1D) Al?C nanoribbons, which are computed to have quite rich characteristics such as direct or indirect band gaps with various values, depending on the direction of the division and the resulting edge configuration. PMID:25102440

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

2014-09-21

447

NbAl Intelligent Material Through Mechanical Alloying  

NASA Astrophysics Data System (ADS)

An intelligent material of Nb-Al composite, is expected to produce intermetallics phase instantaneously upon collision with hypervelocity space debris to stop the crack propagation. Intermetallics-free MA powder with Nb dispersion in Al matrix is targeted. Nb-Al powders are mechanically alloyed using agate media. Mechanical alloying (MA) with agate media produced fine intermetallics-free powder of Nb dispersion in Al matrix. Intermetallics-free critical MA powder curve for agate media were established. The optimum critical agate MA powder of 200 rpm 132 hours had intelligent properties.

Chinniah, K.; Aikra, K.

2010-03-01

448

Spark plasma sintering of SiAlON nanopowders  

NASA Astrophysics Data System (ADS)

The spark plasma sintering (SPS) method was used for sintering of different SiAlON nanopowders obtained by the method of plasma synthesis. Almost entirely dense samples were obtained at 1450-1500 °C (the range of ?-SiAlONs) and under 1600 °C (the range of ?-/?-SiAlONs). Results of research were compared wit that obtained by the method of pressureless sintering. Samples obtained at 1700 °C have similar characteristics, differing only with the time of processing: by the SPS method the sample was obtained during 23 minutes (100 °C/min 5 min.), but by the pressure-less sintering - during 290 minutes (10 °C/min 120 min.). Material obtained by the pressure-less sintering contains the phase of ?- SiAlON, but samples obtained by the SPS process contain almost only the phase of ?- SiAlON and the reason of this effect is a specific crystallization process of nanopowders: firstly at temperatures over 1400 - 1450 °C ?- SiAlON is formed and only after this the formation of ?- SiAlON occurs over 1500-1550 °C. In the case of SPS process a rapid increase of temperature (100 °C/min) and short dwelling time at high temperatures (5 min.) is the reason, why the transition of ?- SiAlON into ?- SiAlON does not occur.

Zalite, I.; Zilinska, N.; Steins, I.; Krastins, J.

2011-12-01

449

Lenguaje Java Avanzado 1 Introduccin al lenguaje Java.......................................................................................4  

E-print Network

Lenguaje Java Avanzado Índice 1 Introducción al lenguaje Java.......................................................................................4 1.1 Java......................................................................................5 1.3 Componentes de un programa Java

Escolano, Francisco

450

Beryllium acceptor binding energy in AlN.  

NASA Astrophysics Data System (ADS)

The acceptor binding energy of an alternative dopant, Be, in AlN epilayers has been probed by time-resolved photoluminescence (PL) spectroscopy. The binding energy of excitons bound to Be acceptors in AlN is determined to be about 33 meV, which implies that the Be acceptor binding energy in AlN is about 0.33 eV in accordance with Haynes' rule. The measured PL decay lifetimes of the acceptor-bound exciton transitions in Be- and Mg-doped AlN (93 and 119 ps, respectively) also indicate that the binding energy of Be acceptor is smaller than that of the most common acceptor dopant in AlN, namely, Mg. The smaller activation energy of Be in AlN has the potential to partly address the critical p-type doping issue in AlN- and Al-rich AlGaN by increasing the room temperature free hole concentration by ˜10^3 compared to the case of Mg doping.

Sedhain, Ashok; Tahtamouni, T. M. Al; Li, Jing; Lin, Jingyu; Jiang, Hongxing

2009-03-01

451

Beryllium acceptor binding energy in AlN  

NASA Astrophysics Data System (ADS)

The acceptor binding energy of an alternative dopant, Be, in AlN epilayers has been probed by time-resolved photoluminescence (PL) spectroscopy. The binding energy of excitons bound to Be acceptors in AlN is determined to be about 33meV, which implies that the Be acceptor binding energy in AlN is about 0.33eV in accordance with Haynes' rule. The measured PL decay lifetimes of the acceptor-bound exciton transitions in Be- and Mg-doped AlN (93 and 119ps, respectively) also indicate that the binding energy of Be acceptor is smaller than that of the most common acceptor dopant in AlN, namely, Mg. The smaller activation energy of Be in AlN has the potential to partly address the critical p-type doping issue in AlN- and Al-rich AlGaN by increasing the room temperature free hole concentration by ˜103 compared to the case of Mg doping.

Sedhain, A.; Al Tahtamouni, T. M.; Li, J.; Lin, J. Y.; Jiang, H. X.

2008-10-01

452

Ca-Al-rich chondrules and inclusions in ordinary chondrites  

NASA Technical Reports Server (NTRS)

Ca-Al-rich objects, hitherto mostly found in carbonaceous chondrites, are shown to be widespread, albeit rare, constituents of type 3 ordinary chondrites. Widespread occurrence and textural similarities of Ca-Al-rich chondrules to common, Mg-Fe-rich chondrules suggest that they formed by related processes. It is suggested in this article that Ca-Al-rich chondrules were formed by total melting and crystallization of heterogeneous, submillimeter- to submillimeter-sized dustballs made up of mixtures of high-temperature, Ca-Al-rich and lower-temperature, Na-K-rich components.

Bischoff, A.; Keil, K.

1983-01-01

453

Photoelectrochemical hydrogen generation with linear gradient Al composition dodecagon faceted AlGaN/n-GaN electrode.  

PubMed

We demonstrated photoelectrochemical cells (PECs) with dodecagon faceted AlGaN/n-GaN heterostructure electrode for H(2) generation, where the AlGaN/n-GaN heterostructure has a linear gradient Al composition (LGAC). The separation efficiency of the photo-generated electron-hole pairs in the electrode performs a key function in the H(2) generation efficiency of PEC cells. The linear gradient Al composition, AlGaN, could create more internal field and light absorption because of the linear graded band gap. Therefore, the zero-bias photocurrent density of PEC cells with dodecagon facet LGAC AlGaN/n-GaN heterostructure electrode is around 5.9 times larger than that of dodecagon faceted n-GaN electrode. PMID:25607499

Lai, W C; Ma, M H; Lin, B K; Hsieh, B H; Wu, Y R; Sheu, J K

2014-12-15

454

Thermoluminescence study of Al2O3 and Y3Al5O12 single crystals irradiated with reactor neutrons  

NASA Astrophysics Data System (ADS)

Al2O3 and Y3Al5O12 singles crystals were irradiated by reactor neutrons at about 40 °C. After irradiation the generated point defects were investigated by optical absorption, thermoluminescence (TL) and differential scanning calorimetry (DSC) techniques. From the experimental data, it is found that 300 nm absorption band observed in Al2O3 and Y3Al5O12 crystals is attributed to Ali+ ion and O- - hole center localized near the cation vacancy respectively. It acts as hole traps with activation energies of 1.4 and 1.3 eV, respectively. Different annealing steps are observed and discussed in both Y3Al5O12 and Al2O3 crystals.

Izerrouken, M.; Meftah, A.; Berkani, S.

2014-05-01

455

Thermoelectric properties of Al substituted misfit cobaltite Ca3(Co1- x Al x )4O9 at low temperature  

NASA Astrophysics Data System (ADS)

Thermoelectric properties of Al substituted compounds Ca3(Co1- x Al x )4O9 ( x = 0, 0.03, 0.05), prepared by a sol-gel process, have been investigated in the temperature range 305-20 K. The results indicate that after Al substitution for Co in Ca3(Co1- x Al x )4O9, the direct current electrical resistivity and thermopower increase due to the reduction of carrier concentration. Experiments show that Al substitution results in decreased lattice thermal conductivity. The figure of merit of temperature behavior suggests that Ca3(Co0.97Al0.03)4O9 would be a promising candidate thermoelectric material for high-temperature thermoelectric application.

Liu, Yi; Chen, Hong-mei; Hu, Jin-lian; Tang, Xu-bing; Li, Hai-jin; Wang, Wei

2014-07-01

456

Al 3p occupied states in Al-Cu-Fe intermetallics and enhanced stability of the icosahedral quasicrystal  

NASA Astrophysics Data System (ADS)

This paper concentrates on a comparison of Al 3p occupied densities of states in crystalline and quasicrystalline Al-Cu-Fe intermetallics. This comparison is made quantitative by computing the two first moments of this partial distribution, which correspond to the partial contribution of Al atoms to the cohesive energy of the material and to the orbital overlap modulated by the coordination number, respectively. From these data, we conclude that the icosahedral quasicrystal and its approximants represent a region of specifically enhanced stability in the Al-Cu-Fe phase diagram. We assign this effect to the specific role played by Al 3p states in the Hume-Rothery mechanism. We confirm the occurrence of a stronger hybridization between Al 3p and Fe 3d states in the icosahedral structure whereas we point out a weaker interaction with Cu 3d states in the icosahedral compounds as compared to stable approximants.

Belin-Ferré, Esther; Fournée, Vincent; Dubois, Jean Marie

2000-09-01

457

Dry Sliding Wear Behavior of a Novel 6351 Al-Al4SiC4 Composite  

NASA Astrophysics Data System (ADS)

In this research work the dry sliding wear behavior of 6351 Al alloy and 6351 Al based composites possessing varying amount of (2-7 vol.%) in situ Al4SiC4 reinforcement was investigated at low sliding speed (1 m/s) against a hardened EN 31 disk at different loads. In general, the wear mechanism involved adhesion and microcutting abrasion. Under selected loads (9.8 and 24.5 N), the overall wear resistance increased with increasing content of Al4SiC4 particles since particles stood tall against the process of wear. Besides, strain hardening of the matrix played an additional role to provide wear resistance. Therefore, the newly developed 6351Al-Al4SiC4 composite can be used as light weight wear resistance component in industry.

Mondal, Manas Kumar; Biswas, Koushik; Saha, Atanu; Maity, Joydeep

2015-02-01

458

Effect of Al-mole fraction in Al{sub x}Ga{sub 1?x}N grown by MOCVD  

SciTech Connect

AlGaN/AlN layers were grown by metalorganic chemical vapor deposition (MOCVD) on sapphire substrates. The Al{sub x}Ga{sub 1?x}N layer composition was varied from 15% to 25%. The crystalline quality, thickness and aluminum (Al) composition of AlGaN were determined using high resolution X-ray diffraction (HRXRD). The growth rate decreases on increasing Al composition. Reciprocal space mapping (RSM) was used to estimate the strain and relaxation between AlGaN and AlN. The optical properties of AlGaN layers were investigated by room temperature Photoluminescence (PL). The AlGaN peak shifts towards lower wavelength with Al composition. The surface morphology of AlGaN was studied by atomic force microscopy (AFM). Root mean square (RMS) roughness values were found to be increased in AlGaN layers with composition.

Jayasakthi, M., E-mail: drbaskar2009@gmail.com; Ramesh, R., E-mail: drbaskar2009@gmail.com; Prabakaran, K., E-mail: drbaskar2009@gmail.com; Loganathan, R., E-mail: drbaskar2009@gmail.com; Kuppulingam, B., E-mail: drbaskar2009@gmail.com; Balaji, M., E-mail: drbaskar2009@gmail.com; Arivazhagan, P., E-mail: drbaskar2009@gmail.com; Sankaranarayanan, S., E-mail: drbaskar2009@gmail.com; Singh, Shubra, E-mail: drbaskar2009@gmail.com; Baskar, K., E-mail: drbaskar2009@gmail.com [Crystal Growth Centre, Anna University, Chennai - 600025 (India)

2014-04-24

459

[A.L. Lavoisier and the anesthetist].  

PubMed

The activity of the anesthesiologist is centered upon the respiratory organ function; therefore, the question of how the fundamental knowledge of gas exchange was gained seems justified. During the 18th century, the elegant but incorrect phlogiston theory (G.E. Stahl, 1659-1734) dominated all theoretical conceptions about combustion and respiration. Chemistry at that time was a collection of observations without any sound hypothetical background. Our knowledge about oxidation, combustion, and respiration was developed mainly by the work of A.L. Lavoisier (1743-1794). He observed that metals gain weight during their calcination (oxidation) and concluded that air is taken up during this process. In these experiments he also proved that air consists of two elastic fluids (gases), one respirable and the other nonrespirable. After experiments with a sparrow breathing in a closed vessel until it expired, Lavoisier stated that during respiration respirable air (O2) is changed into fixed air (CO2) in the lungs with the mephitic portion of the air (N2) not taking part. These were the first investigations of respiration where accurate and reproduciable methods were applied. Respirable air is also transformed into fixed air by a burning candle. After investigations by which thermochemistry was founded, respiration could be defined as a slow form of combustion. In these and other biologically oriented experiments, Lavoisier developed direct and indirect calorimetry. He named respirable gas oxygen and explained the composition of water. In refuting the phlogiston theory, he established modern chemistry. His fate was sealed during the French revolution: in 1794 he was executed as a consequence of his activities as a farmer.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3063131

Braun, U

1988-11-01

460

Influence of reaction temperature for the manufacturing of Al–3Ti and Al–3B master alloys  

Microsoft Academic Search

In the present work, binary Al–3Ti and Al–3B master alloys were prepared at different reaction temperatures in an induction furnace by the reaction of halide salts like potassium fluoborate and potassium titanium fluoride with liquid molten Al. The reaction temperatures of 800, 900 and 1000°C were selected while the reaction time was kept constant at 60min for the preparation of

V. Auradi; S. A. Kori

2008-01-01

461

Characterization of reinforcement distribution in Al\\/(Al 2O 3) p composites obtained from composite powder  

Microsoft Academic Search

A composite powder Al–(Al2O3)p obtained in a rotary-vibration mill was used as a semifinished component to manufacture particle-reinforced metal matrix composites (PRMMCs) using cast and powder metallurgy technologies. For a quantitative description of the inhomogeneity of Al2O3 particle distributions in the aluminum matrix the following methods were applied: nearest neighbor distance, radial distribution function, influence zone morphology, systematic scanning and

Anita Olszówka-Myalska; Janusz Szala; Jan Cwajna

2001-01-01

462

Influence of Al–Al 2O 3 composite powder on the matrix microstructure in composite casts  

Microsoft Academic Search

The structural characterization is presented of composite casts with an AlMg4 alloy matrix, with the composite powder (Al–Al2O3)cp reinforcement obtained in a rotary-vibration mill. On the cross-sections of ingots, metallographic specimens have been made and, by means of quantitative metallographic methods, the grain size distributions have been determined. Statistical tests of the results obtained from the grain plane section area

Anita Olszówka-Myalska; Janusz Szala; Józef ?leziona; Boles?aw Formanek; Jerzy Myalski

2002-01-01

463

Measurement of Young's modulus and internal friction of an in situ Al-Al3Ni functionally gradient material  

Microsoft Academic Search

An in situ Al-Al3Ni functionally gradient material (FGM) was produced by centrifugally casting an Al-20 mass% Ni alloy into a thick-walled tube. Four specimens, 90 mm long, with rectangular cross-sections (width × thickness) of 6 × 6, 6 × 5, 6 × 4 and 6 × 3 mm2 were machined from the tube such that the thickness direction of the

Y. Fukui; K. Takashima; C. B. Ponton

1994-01-01

464

Hole transport across the (Al,Ga)(As,Sb) barrier in InAs-(Al,Ga)(As,Sb) heterostructures  

Microsoft Academic Search

We investigate the current transport across the (Al,Ga)(As,Sb) barrier in InAs-(Al,Ga)(As,Sb) heterostructures and show that the transport mechanism consists of thermionic emission of holes over the valence band barrier. Temperature-dependent I-V measurements are performed on diodes fabricated from three samples with different compositions of the top (Al,Ga)(As,Sb) barrier. Consistent with picture of thermionic hole transport in the valence band, we

Berinder Brar; Herbert Kroemer

1998-01-01

465

Al26 and O-16 in the early solar system - Clues from meteoritic Al2O3  

Microsoft Academic Search

The study focuses on 26 Al2O3 grains up to 20 micron in size recovered from the Murchison C2 chrondite. It is observed that Mg-26\\/Mg-24 ranges up to 56 times the solar system ratio, but the initial Al-26\\/Al-27 ratios do not exceed the canonical maximum of 0.00005 in other meteoritic samples. It is concluded that this ratio represents the abundance of

Edward Anders; Roy S. Lewis; Alois Virag; Ernst Zinner

1991-01-01

466

Thermal cycling response and oxidation behavior of Al 2O 3\\/NiAl composites with interfacial Mo coating  

Microsoft Academic Search

Thermal cycling response and oxidation behavior of Al2O3\\/NiAl composites with interfacial Mo coating were studied and results compared with that for weakly bonded composites without any interfacial coating. Thermal cycling of composites with interfacial Mo coating from room temperature to 1300 K in an inert atmosphere resulted in interfacial debonding along the Mo-Al2O3 interface, with the extent of debonding increasing

Ajay K Misra; Randy R Bowman

1995-01-01

467

The removal of bisphenol A from aqueous solutions by MIL-53(Al) and mesostructured MIL-53(Al).  

PubMed

In this work, metal-organic framework MIL-53(Al){Al(OH)[O2C-C6H4-CO2]} and MIL-53(Al)-F127{Al(OH)[O2C-C6H4-CO2]} were synthesized and used as sorbents to remove bisphenol A (BPA) from aqueous system. The sorption kinetics data of BPA were found to be in agreement with the pseudo-second-order model. The equilibrium sorption amounts of BPA on MIL-53(Al) and MIL-53(Al)-F127 reached 329.2±16.5 and 472.7±23.6 mg g(-1), respectively, far more than that of commercial activated carbons (ranging from 129.6 to 263.1 mg g(-1)). Both MIL-53(Al) and MIL-53(Al)-F127 could remove BPA fast from aqueous solutions, and the required contact time to reach equilibrium was approximately 90 min for MIL-53(Al) and 30 min for MIL-53(Al)-F127, respectively. The optimum pH levels for the removal of BPA using MIL-53 (Al) and MIL-53(Al)-F127 were 4 and 6 separately. The optimum temperature for the sorption behavior of BPA on the two sorbents was 20 °C. The results performed show that the resulting products, as one kind of MOFs, can be regarded as a new class of sorbents for water treatment and could find great applications in the fields of environmental water pollution control and resources reuse. PMID:23764233

Zhou, Meimei; Wu, Yi-Nan; Qiao, Junlian; Zhang, Jing; McDonald, Amanda; Li, Guangtao; Li, Fengting

2013-09-01

468

LOW CYCLE FATIGUE AND FATIGUE CRACK GROWTH IN Al-Li, Al-Li-Zr AND 8090 ALLOYS  

Microsoft Academic Search

The evolution of the properties in low cycle fatigue and fatigue crack growth of binary Al-Li, ternary Al-Li-Zr and 8090 alloys were compared. The respective influences of the main microscopic features of Al-Li alloys were studied. The shearing of S' precipitates induces the formation of intense and heterogeneous slip bands (PSB) and of intergranular cracking. The A13 Zr precipitates prevent

Y. XIAO; P. Bompard

1987-01-01

469

Advantages of deep-UV AlGaN light-emitting diodes with an AlGaN/AlGaN superlattices electron blocking layer  

NASA Astrophysics Data System (ADS)

In this work, the AlGaN/AlGaN superlattices (SLs) electron blocking layer (EBL) is designed to replace conventional AlGaN EBL in the AlGaN-based deep-UV light-emitting diodes (DUV-LEDs). The simulation results show that the DUV-LEDs with SLs possess higher emission power and internal quantum efficiency as compared to those with conventional EBL, which is attributed to the suppression of electron leakage and the enhancement of hole injection efficiency due to the alleviated strain force and the appropriately modified energy band caused by SLs EBL. The results also demonstrate that the efficiency droop is markedly reduced when the SLs EBL is adopted.

Yin, Yi An; Wang, Naiyin; Li, Shuti; Zhang, Yong; Fan, Guanghan

2015-04-01

470

Advantages of deep-UV AlGaN light-emitting diodes with an AlGaN/AlGaN superlattices electron blocking layer  

NASA Astrophysics Data System (ADS)

In this work, the AlGaN/AlGaN superlattices (SLs) electron blocking layer (EBL) is designed to replace conventional AlGaN EBL in the AlGaN-based deep-UV light-emitting diodes (DUV-LEDs). The simulation results show that the DUV-LEDs with SLs possess higher emission power and internal quantum efficiency as compared to those with conventional EBL, which is attributed to the suppression of electron leakage and the enhancement of hole injection efficiency due to the alleviated strain force and the appropriately modified energy band caused by SLs EBL. The results also demonstrate that the efficiency droop is markedly reduced when the SLs EBL is adopted.

Yin, Yi An; Wang, Naiyin; Li, Shuti; Zhang, Yong; Fan, Guanghan

2015-02-01

471

Thermal expansion of gehlenite, Ca2Al[AlSiO7], and the related aluminates LnCaAl[Al2O7] with Ln=Tb, Sm  

NASA Astrophysics Data System (ADS)

The thermal expansion of gehlenite, Ca2Al[AlSiO7], (up to T=830 K), TbCaAl[Al2O7] (up to T=1,100 K) and SmCaAl[Al2O7] (up to T=1,024 K) has been determined. All compounds are of the melilite structure type with space group Pbar {4}2_1 m. Thermal expansion data was obtained from in situ X-ray powder diffraction experiments in-house and at HASYLAB at the Deutsches Elektronen Synchrotron (DESY) in Hamburg (Germany). The thermal expansion coefficients for gehlenite were found to be: ?1=7.2(4)×10-6 K-1+3.6(7)×10-9? T K-2 and ?3=15.0(1)×10-6 K-1. For TbCaAl[Al2O7] the respective values are: ?1=7.0(2)×10-6 K-1+2.0(2)×10-9? T K-2 and ?3=8.5(2)×10-6 K-1+2.0(3)×10-9? T K-2, and the thermal expansion coefficients for SmCaAl[Al2O7] are: ?1=6.9(2)× 10-6 K-1+1.7(2)×10-9? T K-2 and ?3=9.344(5)×10-6 K-1. The expansion-mechanisms of the three compounds are explained in terms of structural trends obtained from Rietveld refinements of the crystal structures of the compounds against the powder diffraction patterns. No structural phase transitions have been observed. While gehlenite behaves like a ’proper’ layer structure, the aluminates show increased framework structure behaviour. This is most probably explained by stronger coulombic interactions between the tetrahedral conformation and the layer-bridging cations due to the coupled substitution (Ca2++Si4+)-( Ln 3++Al3+) in the melilite-type structure.

Peters, L.; Knorr, K.; Knapp, M.; Depmeier, W.

2005-11-01

472

26Al and 60Fe yields from AGB stars  

NASA Astrophysics Data System (ADS)

We present yields for 26Al and 60Fe from asymptotic giant branch (AGB) stars. For AGB stars of masses lower than ?4 M ? yields are of the order of only 10 -7 M ?, while for AGB stars of higher masses yields are up to 10 -5 M ?. In these massive AGB stars 26Al is produced via 25Mg( p, ?) 26Al reactions when proton captures occur at the base of the convective envelope (hot bottom burning), while 60Fe is produced via the operation of the 59Fe( n, ?) 60Fe reaction when high neutron densities result from the activation of the 22Ne( ?, n) 25Mg neutron source during thermal pulses. Large nuclear and stellar uncertainties are associated with these predictions, ranging from the rate of the 26Al + p reaction to the amount of material carried from the He-rich shell to the convective envelope via the third dredge-up. When compared to the contribution from core-collapse supernovae, the overall contribution of AGB stars to the Galactic inventory of 26Al and 60Fe is insignificant. On the other hand, a massive AGB star may have polluted the early solar system with short lived radioactive nuclei since we obtain a self-consistent match for the abundances of 41Ca, 26Al, 60Fe, and 107Pd using our 6.5 M ? model. Finally, the interpretation of the 26Al/ 27Al ratios in the majority of meteoritic stellar grains from low-mass AGB stars is hindered by the three orders of magnitude error bar of the 26Al( p, ?) 27Si reaction. Grains with very high 26Al/ 27Al ratios may represent evidence for extra-mixing phenomena in AGB stars or for a post-AGB origin.

Lugaro, Maria; Karakas, Amanda I.

2008-10-01

473

Microstructural investigations on as-cast and annealed Al-Sc and Al-Sc-Zr alloys  

SciTech Connect

Al-Sc and Al-Sc-Zr alloys containing 0.05, 0.1 and 0.5 wt.% Sc and 0.15 wt.% Zr were investigated using optical microscopy, electron microscopy and X-ray diffraction. The phase composition of the alloys and the morphology of precipitates that developed during solidification in the sand casting process and subsequent thermal treatment of the samples were studied. XRD analysis shows that the weight percentage of the Al{sub 3}Sc/Al{sub 3}(Sc, Zr) precipitates was significantly below 1% in all alloys except for the virgin Al0.5Sc0.15Zr alloy. In this alloy the precipitates were observed as primary dendritic particles. In the binary Al-Sc alloys, ageing at 470 deg. C for 24 h produced precipitates associated with dislocation networks, whereas the precipitates in the annealed Al-Sc-Zr alloys were free of interfacial dislocations except at the lowest content of Sc. Development of large incoherent precipitates during precipitation heat treatment reduced hardness of all the alloys studied. Growth of the Al{sub 3}Sc/Al{sub 3}(Sc, Zr) precipitates after heat treatment was less at low Sc content and in the presence of Zr. Increase in hardness was observed after heat treatment at 300 deg. C in all alloys. There is a small difference in hardness between binary and ternary alloys slow cooled after sand casting.

Lohar, A.K., E-mail: adityalohar@yahoo.co.in [Centre for Advanced Materials Processing, CMERI, Durgapur 713209 (India); Mondal, B. [Centre for Advanced Materials Processing, CMERI, Durgapur 713209 (India); Rafaja, D.; Klemm, V. [Institute of Materials Science, TU Bergakademie Freiberg (Germany); Panigrahi, S.C. [Dept. of Metallurgical and Materials Engineering, IIT Kharagpur 700 302 (India)

2009-11-15

474

Nonequilibrium synthesis of NbAl3 and Nb-Al-V alloys by laser cladding. II - Oxidation behavior  

NASA Technical Reports Server (NTRS)

Isothermal oxidation behaviors of NbAl3 alloy synthesized by laser cladding were investigated at temperatures between 800 and 1400 C, and the effect of vanadium microalloying on the oxidation of the laser-clad alloy was examined. The oxidation kinetics of the two alloys were monitored using thermal gravimetric weight gain data, and the bulk and surface chemistries were analyzed using XRD and XPS, respectively. It was found that NbAl3 did not form an exclusive layer of protective Al2O3. The oxidation products at 800 C were found to be a mixture of Nb2O5 and Al2O3. At 1200 C, a mixture of NbAlO4, Nb2O5, and Al2O3 formed; and at 1400 C, a mixture of NbAlO4, Al2O3, NbO2, NbO(2.432), and Nb2O5 formed. The addition of V led to a dramatic increase of the oxidation rate, which may be related to the formation of (Nb, V)2O5 and VO2, which grows in preference to protective Al2O3.

Haasch, R. T.; Tewari, S. K.; Sircar, S.; Loxton, C. M.; Mazumder, J.

1992-01-01

475

Measurements of Al concentration in the primary Si crystals from the rheocast Al-15.5 wt% Si alloy  

SciTech Connect

The purpose of the present study is to investigate the distribution of Al in the primary crystal of Si in rheocast hypereutectic Al-Si alloy. Lattice parameters of primary Si crystals were determined using relative positions of the higher order Laue zone (HOLZ) lines recorded from the CBED patterns. The measured lattice parameters were then converted to the Al concentrations to compare with EPMA measurements for the accurate determination of solute concentration profile in the primary Si and to understand the role of solute redistribution on the microstructural change in hypereutectic Al-Si alloy during rheocasting.

Kim, G.H.; Lee, J.C.; Lee, H.I. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of)] [Korea Inst. of Science and Technology, Seoul (Korea, Republic of); Lee, J.I. [Chungju National Univ. (Korea, Republic of). Dept. of Materials Science and Engineering] [Chungju National Univ. (Korea, Republic of). Dept. of Materials Science and Engineering

1997-10-01

476

Trap states in InAlN/AlN/GaN-based double-channel high electron mobility transistors  

NASA Astrophysics Data System (ADS)

We present a detailed analysis of trap states in InAlN/AlN/GaN double-channel high electron mobility transistors grown by pulsed metal organic chemical vapor deposition. By frequency dependent conductance measurements, trap densities and time constants at both InAlN/AlN/GaN interfaces were determined. Two types of traps, with a high density of up to ˜1014 cm-2 eV-1, were observed existing at the higher InAlN/AlN/GaN interface. On the other hand, the density dramatically decreased to ˜1012 cm-2 eV-1 for traps located at lower InAlN/AlN/GaN interface on which a low-temperature grown GaN (LT-GaN) layer was deposited. Additionally, photo-assisted capacitance-voltage measurements were performed to estimate deep-level defects, yielding a low density of 1.79 × 1011 cm-2 acting as negative fixed charges at the LT-GaN and lower InAlN interface.

Zhang, Kai; Xue, JunShuai; Cao, MengYi; Yang, LiYuan; Chen, YongHe; Zhang, JinCheng; Ma, XiaoHua; Hao, Yue

2013-05-01

477

Development of dispersion U(Mo)/Al-Si miniplates fabricated at 500 °C with Al 6061 as cladding  

NASA Astrophysics Data System (ADS)

In the frame of U(Mo) dispersion fuel elements qualification, Si additions to Al matrix arose as a promising solution to the unacceptable failures found when pure Al is used. Analysis of as-fabricated fuel plates made with Al-Si matrices demonstrated that good irradiation behavior is correlated with the formation during fabrication of a Si-containing interaction layer around the U(Mo) particles. Thus, the analysis of the influence of fabrication parameters becomes important. Studies on Al-Si dispersion miniplates fabricated in CNEA, Argentina, have been initiated to determine how to obtain the better interaction layer characteristics with the lesser modifications to the fabrication process and the smaller amount of Si in the matrix. In this work results for miniplates made of atomized U-7 wt%Mo particles dispersed in Al-2 wt%Si and Al-4 wt%Si matrices, obtained by mixing pure Al and Si powders, and Al 6061 as cladding are presented. Interaction layer grown during fabrication process (500 °C) consists of Si-containing phases being U(Al, Si)3 its principal component. Its uniformity is not satisfactory due to the formation of an oxide layer.

Mirandou, M. I.; Aricó, S. F.; Balart, S. N.; Fabro, J. O.

2015-02-01

478

Hybrid aluminum and indium conducting filaments for nonpolar resistive switching of Al/AlOx/indium tin oxide flexible device  

NASA Astrophysics Data System (ADS)

The nonpolar resistive switching characteristics of an Al/AlOx/indium tin oxide (ITO) device on a plastic flexible substrate are investigated. By analyzing the electron diffraction spectroscopy results and thermal coefficient of resistivity, it is discovered that the formation of aluminum and indium conducting filaments in AlOx film strongly depends on the polarity of the applied voltage. The metal ions arising from the Al and ITO electrodes respectively govern the resistive switching in corresponding operation polarity. After 104 times of mechanical bending, the device can perform satisfactorily in terms of resistance distribution, read sequence of high and low resistive states, and thermal retention properties.

Yuan, Fang; Wang, Jer-Chyi; Zhang, Zhigang; Ye, Yu-Ren; Pan, Liyang; Xu, Jun; Lai, Chao-Sung

2014-02-01

479

Which aluminium fractionation method will give true inorganic monomeric Al results in fresh waters (not including colloidal Al)?  

PubMed

Aluminium solubility and toxicity increase with acidification. There is no standardized analytical method for the determination of inorganic monomeric Al (Al(im)), which is the form that causes toxicity to fish. Separation by cation exchange is commonly combined with other analytical methods, such as complexation with pyrochatechol violet (PCV) or 8-hydroxyquinoline (HQ) and total quantification using graphite furnace or inductively-coupled plasma emission. Data from 14 laboratories were obtained for a dilution series of Al(im) samples; the results of the Al(im) analysis were statistically evaluated. The Al(im) levels were altered through pH, which was controlled by the addition of calcium hydroxide. Confounding parameters such as total organic carbon (TOC) or fluoride (F) were controlled. The total determination and HQ methods yielded significantly higher Al(im) concentrations than the PCV method. Pretreatment by passage through a 0.45 microm filter and pH-adjustment of the ion exchange column had no apparent effect on the Al(im) yield. However, ultra filtration (<10 kDa) caused a significant reduction in the Al(im) concentration using the HQ method. The ultra filtrated Al(im) fraction was similar to the PCV results in the interlaboratory comparison. Retention of colloidal bound Al in the cation exchange column may result in overestimation of Al(im) when the total and HQ methods are used. Estimated Al(im) concentrations derived from two equilibrium models were similar to PCV-derived Al(im) concentrations, as well as the HQ method using ultra filtrated water. The fact that the PCV method does not detect colloidal Al, neither before nor after ion exchange, makes this a preferred technique for Al(im) analysis. Because of the variability in the reported Al(im) concentrations that can arise when different analytical procedures are used, the adoption of a single, reliable technique will facilitate inter-study comparisons and provide consistency in the detection of trends in environmental monitoring programs. PMID:19724834

Andrén, Cecilia M; Rydin, Emil

2009-09-01

480

Laser irradiation of ZnO:Al/Ag/ZnO:Al multilayers for electrical isolation in thin film photovoltaics  

PubMed Central

Laser irradiation of ZnO:Al/Ag/ZnO:Al transparent contacts is investigated for segmentation purposes. The quality of the irradiated areas has been experimentally evaluated by separation resistance measurements, and the results are complemented with a thermal model used for numerical simulations of the laser process. The presence of the Ag interlayer plays two key effects on the laser scribing process by increasing the maximum temperature reached in the structure and accelerating the cool down process. These evidences can promote the use of ultra-thin ZnO:Al/Ag/ZnO:Al electrode in large-area products, such as for solar modules. PMID:24053228

2013-01-01

481

UV Raman spectra of AlN and AlInN films grown on various substrates  

NASA Astrophysics Data System (ADS)

We discuss Raman spectra of epitaxial AlN films grown by Plasma Source MBE on sapphire (0001), 6H SiC, Si(111) and Si(001). Film thickness ranged from 100 to 300 nm. The alloys as well as the AlN films on sapphire (0001), 6H SiC, and Si(111) are of the Wurtzite polytype with a strong c-plane texture, whereas those on Si(001) are of the zincblende type with (001) texture. Excitation with 244 nm (5 eV) radiation gives substantial enhancement of the AlN and Al rich AlInN spectra with respect to that of the substrates because of the near resonance of their bandgap with the excitation energy. AlN/sapphire spectra yield A_1(TO), E_2, and A_1(LO) modes at 612, 652 and 884 cm-1, respectively. These are slightly lower than corresponding values reported for bulk AlN, probably because of strain in the films. AlN/SiC shows bands near 666 and 895 cm-1, which might indicate less strained films caused by a better lattice match. In Al_1-xIn_xN the A_1(LO) mode shifts to lower frequency with increasing x. The increased resonance enhancement at x ~ 0.1 leads to strong second- and third-order spectra. Work supported by NSF-IGERT-DGE-9870720

Naik, V. M.; Lukitsch, M. J.; Thompson, M. P.; Rimai, L.; Auner, G. W.; Naik, R.; Weber, W. H.; Uy, D.

2001-03-01

482

High pressure X-ray diffraction study of LaAl 2 and LaAl 3  

NASA Astrophysics Data System (ADS)

LaAl 2 and LaAl 3 exhibit MgCu 2 type (space group Fd3m) and Ni 3Sn type (space group P6 3/mmc) structures, respectively, at NTP. High pressure X-ray diffraction studies on these two systems are carried out up to ?35 and ?30 GPa, respectively, with a diamond anvil cell, mounted on a high precision Guinier diffractometer. The volume compression determined at the highest pressures are about 33% for LaAl 2 and 23% for LaAl 3. Neither compound shows any structural transition.

Sekar, M.; Chandra Shekar, N. V.; Sahu, P. Ch.; Sanjay Kumar, N. R.; Rajan, K. Govinda

2002-11-01

483

TiAlN and TiAlCN deposition in an industrial PaCVD-plant  

Microsoft Academic Search

An industrial PaCVD-plant was equipped with an AlCl3-generator. By using Ar, H2, N2, CH4, TiCl4 and AlCl3, TiAlN- and TiAlCN-films could be deposited on hard metal and steel substrates. The plasma was generated by a DC-pulse power supply with frequencies up to 50 kHz. The reactor size was 350 mm in diameter and 900 mm in height. During one batch

D. Heim; R. Hochreiter

1998-01-01

484

N vacancy, substitutional O, and Al defects in the bandgap of composition-tunable nonstoichiometric AlN powder  

NASA Astrophysics Data System (ADS)

AlN powders are prepared by direct nitridation via Al liquid and vapor phases in mixed atmospheres of N2 and NH3 with different NH3/N2 ratios. The reaction analysis reveals that NH3 acts as catalyst for N2 dissociation and the transportations of N, O, and Al in the liquid phase are different from those in the vapor phase. Accordingly, the products are Al-rich and composition-tunable nonstoichiometric AlN in which N, O, and Al content values change with nitridation atmosphere and temperature, leading to the variation of the relevant defect concentration. Therefore, the AlN powders exhibit prominent absorption bands around 5.30, 3.40, and 1.50 eV, which are tentatively assigned to VN, ON donors, and AlN acceptor respectively. Furthermore, a new donor named [VN—ON] complex is predicted at 4.40 eV within the 5.90 eV bandgap. It is demonstrated that the optical spectra of nonstoichiometric AlN are preferable to the nominal stoichimometric one for the identification of the defects energy level.

Zhang, Dian; Liu, Fa-Min; Cai, Lu-Gang

2014-06-01

485

Oxidation Resistant Ti-Al-Fe Diffusion Barrier for FeCrAlY Coatings on Titanium Aluminides  

NASA Technical Reports Server (NTRS)

A diffusion barrier to help protect titanium aluminide alloys, including the coated alloys of the TiAl gamma + Ti3Al (alpha2) class, from oxidative attack and interstitial embrittlement at temperatures up to at least 1000 C is disclosed. The coating may comprise FeCrAlX alloys. The diffusion barrier comprises titanium, aluminum, and iron in the following approximate atomic percent: Ti-(50-55)Al-(9-20)Fe. This alloy is also suitable as an oxidative or structural coating for such substrates.

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

1996-01-01

486

Raman scattering study of InGaAs\\/AlAsSb and InGaAs\\/AlAs\\/AlAsSb heterostructures  

Microsoft Academic Search

We report here on a detailed Raman scattering study of InGaAs\\/AlAsSb superlattices (SLs) and quantum-wells (QWs)