Science.gov

Sample records for aplicados al analisis

  1. Estadistica I Tema 3: Analisis de datos bivariantes

    E-print Network

    Gil, Ana Arribas

    Estad´istica I Tema 3: An´alisis de datos bivariantes Tema 3: An´alisis de datos bivariantes recomendadas Pe~na, D. y Romo, J., Introducci´on a la Estad´istica para las Ciencias Sociales. Cap´itulos 7, 8 y 9. Newbold, P. Estad´istica para los Negocios y la Econom´ia. Secciones 2.5 y 12.1­12.4. #12;Datos

  2. Calcolo 2B -Analisi III maggio 2005

    E-print Network

    Catenacci, Roberto

    cartesiane, essendo div~v = 4y; si ha: Z Z Z V div~v dV = Z sinh 1 0 Z Z D(y) 4ydxdz dy dove D(y) e il disco corrispondente al campo vettoriale sul disco in y = sinh 1 (il disco e parametrizzato da: x = cos ; z = sin ; 0 p cosh4 1 Si osserva poi che il campo vettoriale e nullo sul disco situato in y = 0 quindi il usso

  3. Notas de Analisis Real (en construccion-version 0.3.4.5)

    E-print Network

    De Nápoli, Pablo Luis

    Notas de An´alisis Real (en construcci´on- versi´on 0.3.4.5) c 2007-2009 Pablo L. De N´apoli 7 de Integrables . . . . . . . . . . . . . . . . . . . . . . . . . 52 3. Construcci´on de medidas 56 3.1. Medidas

  4. Compito di Analisi Matematica I: Calcolo differenziale, Corso di Laurea in Informatica, Mercoledi, 26 aprile 2000

    E-print Network

    Magnanini, Rolando

    ´i, 26 aprile 2000 1) Studiare la funzione f(x) = x - 3 ln 1 + x2 + arctan x completa di eventuali Analisi Matematica I: Calcolo differenziale, Corso di Laurea in Informatica, Mercoled´i, 26 aprile 2000 1 estremi relativi, flessi ed asintoti. Disegnarne il grafico. 2) Studiare il carattere della serie: + n=1 1

  5. Doc. de trabajo Fondef D05I-10211. Prohibida su reproduccion ANALISIS NUMERICO

    E-print Network

    Osses, Axel

    Doc. de trabajo Fondef D05I-10211. Prohibida su reproducci´on ANALISIS NUMERICO Axel Osses A, Universidad de Chile, Pro- yecto FONDEF D05I-10211 E-mail address: axosses@dim.uchile.cl #12;Doc. de trabajo estudiantes de pedagog´ia en matem´aticas. Est´a prohibida su reproducci´on parcial o total. #12;Doc. de

  6. I numeri reali Note per il corso di Analisi Matematica 1

    E-print Network

    Mauceri, Giancarlo

    I numeri reali Note per il corso di Analisi Matematica 1 G. Mauceri a.a. 2003-04 #12;2 I numeri reali Contents 1 Introduzione 3 2 Gli assiomi di campo 3 3 Gli assiomi dell'ordine 4 4 Valore assoluto 5 12 8 L'assioma di completezza 12 9 Conseguenze della completezza 14 10 Archimedeit`a dei reali 16 11

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

    NASA Astrophysics Data System (ADS)

    Rivera Pacheco, Andres

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

  8. Darlington AL O'Reillys AL

    E-print Network

    Greenslade, Diana

    AL Miami Nicolls Br AL Oyster Ck AL Coplicks Br AL Burleigh Waters AL NEW SOUTH WALES Coolangatta AWS Steiglitz Wharf AL Loder Ck AL SURFERS PARADISE Air Sea Rescue AL Gold Coast Seaway TM Gold Coast Seaway AWS

  9. 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) ...

  10. ALS Association

    MedlinePLUS

    ... and nationwide advocacy while also empowering people with Lou Gehrig's Disease and their families to live fuller lives by ... in the search to treat and cure this disease. Join Us ... are owned and copyrighted by The ALS Association . ©2015 Lou Gehrig® used with permission of the Rip Van Winkle ...

  11. Profiling, analisi delle prestazioni e proposte per l'ottimizzazione del RDBMS MySQL utilizzato dal progetto DIRAC/LHCbDIRAC

    E-print Network

    Mesin, Alberto

    Il lavoro presentato in questa tesi riguarda lo studio, l'analisi e la formula- zione di proposte per il miglioramento del database di back-end del progetto DIRAC/LHCbDIRAC. LHCbDIRAC, basato su DIRAC, e il sistema di sot- tomissione per l'accesso all'infrastruttura distribuita Grid per l'esperimento LHCb del CERN. Ad esso e adata la gestione dei job di Produzione, Mer- ge, Ricostruzione degli Eventi e Analisi per i dati sperimentali e simulati. Il sistema utilizza un RDBMS MySQL per la gestione di numerosi databa- se. La volonta di passare ad un motore relazionale e transazionale per la denizione schemi e la possibilita che, in un recente futuro, il DBMS possa rappresentare un serio limite alle prestazioni del sistema stesso hanno reso necessario questo studio. Il lavoro svolto si e concentrato sul proling di un singolo schema relazionale per il quale sono stati utilizzati metodi di analisi e fornite soluzioni ai problemi riscontrati il quanto piu possibile generali e per tanto validi per l'intero sistema. L...

  12. [AL amyloidosis].

    PubMed

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

    2015-02-01

    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

  13. Amyotrophic Lateral Sclerosis (ALS)

    MedlinePLUS

    ... Awards Enhancing Diversity Find People About NINDS NINDS Amyotrophic Lateral Sclerosis (ALS) Information Page Clinical Trials Natural History and ... en Español Additional resources from MedlinePlus What is Amyotrophic Lateral Sclerosis (ALS)? Amyotrophic lateral sclerosis (ALS), sometimes called Lou ...

  14. 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)

    Davila Montanez, Melissa

    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.

  15. Initial Symptoms of ALS

    MedlinePLUS

    ... Start a Fund Start your own fundraising event & help create a world without ALS Start an Event Join this nationwide movement by walking for those affected by ALS Sign Up Now Site Map | Press Room | FAQ | Privacy Policy | ...

  16. Who Gets ALS?

    MedlinePLUS

    ... Start a Fund Start your own fundraising event & help create a world without ALS Start an Event Join this nationwide movement by walking for those affected by ALS Sign Up Now Site Map | Press Room | FAQ | Privacy Policy | ...

  17. ALS longitudinal kickers

    SciTech Connect

    Voelker, F.

    1992-10-01

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

  18. Ventilatory Control in ALS

    PubMed Central

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

    2015-01-01

    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

  19. ALS2 mutations

    PubMed Central

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

    2014-01-01

    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

  20. What Is ALS?

    MedlinePLUS

    ... the gene mutation and may develop the disease. French neurologist Jean-Martin Charcot discovered the disease in ... reverses ALS, scientists have made significant progress in learning more about this disease . In addition, people with ...

  1. All About ALS

    MedlinePLUS

    ... External link, please review our exit disclaimer . Subscribe All About ALS Understanding a Devastating Disorder In the ... a coffee pot, or button a shirt. Eventually, all muscles under voluntary control are affected, and people ...

  2. ALS (Amyotrophic Lateral Sclerosis)

    MedlinePLUS

    ... occupational factors. For example, studies of populations of military personnel who were deployed to the Gulf region during ... were more likely to develop ALS compared to military personnel who were not in the region. Future research ...

  3. Genetic Testing for ALS

    MedlinePLUS

    ... Involved Donate 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 ...

  4. Frequently Asked Questions about ALS and the ALS Registry

    MedlinePLUS

    ... please visit this page: About CDC.gov . National Amyotrophic Lateral Sclerosis (ALS) Registry Email Print ATSDR Join the Registry | ... to Top ALS Registry Home Registry Resources About Amyotrophic Lateral Sclerosis ALS Registry Agency for Toxic Substances and Disease ...

  5. 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)

    Isidro Villamizar, Gloria Maria

    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.

  6. ALS superbend magnet system

    SciTech Connect

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

    2000-09-15

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

  7. Modulus measurements in ordered Co-Al, Fe-Al, and Ni-Al alloys

    NASA Technical Reports Server (NTRS)

    Harmouche, M. R.; Wolfenden, A.

    1985-01-01

    The composition and/or temperature dependence of the dynamic Young's modulus for the ordered B2 Co-Al, Fe-Al, and Ni-Al aluminides has been investigated using the piezoelectric ultrasonic composite oscillator technique (PUCOT). The modulus has been measured in the composition interval 48.49 to 52.58 at. pct Co, 50.87 to 60.2 at. pct Fe, and 49.22 to 55.95 at. pct Ni for Co-Al, Fe-Al, and Ni-Al, respectively. The measured values for Co-Al are in the temperature interval 300 to 1300 K, while those for the other systems are for ambient temperature only. The data points show that Co-Al is stiffer than Fe-Al, which is stiffer than Ni-Al. The data points for Fe-Al and Ni-Al are slightly higher than those reported in the literature.

  8. Fosetyl-al

    Integrated Risk Information System (IRIS)

    Fosetyl - al ; CASRN 39148 - 24 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  9. Brambilla, et al. Reply

    E-print Network

    Giovanni Brambilla; Djamel El Masri; Matteo Pierno; Ludovic Berthier; Luca Cipelletti; George Petekidis; Andrew B. Schofield

    2010-08-27

    Brambilla, et al. Reply: van Megen and Williams (vMW) question our recent claim that dense colloidal hard spheres enter at large volume fraction \\phi a dynamical regime not observed in earlier work and not described by the mode-coupling theory (MCT) of the glass transition.

  10. ALS insertion devices

    SciTech Connect

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

    1990-11-01

    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.

  11. Jasechko et al. reply.

    PubMed

    Jasechko, Scott; Sharp, Zachary D; Gibson, John J; Birks, S Jean; Yi, Yi; Fawcett, Peter J

    2014-02-13

    replying to A. M. J. Coenders-Gerrits et al. 506, http://dx.doi.org/10.1038/nature12925 (2014)In their Comment, Coenders-Gerrits et al. suggest that our conclusion that transpiration dominates the terrestrial water cycle is biased by unrepresentative input data and optimistic uncertainty ranges related to runoff, interception and the isotopic compositions of transpired and evaporated moisture. We clearly presented the uncertainties applied in our Monte-Carlo sensitivity analysis, we reported percentile ranges of results rather than standard deviations to best communicate the nonlinear nature of the isotopic evaporation model, and we highlighted that the uncertainty in our calculation remains large, particularly in humid catchments (for example, figure 2 in our paper). PMID:24522604

  12. Al Jazirah, Sudan

    NASA Technical Reports Server (NTRS)

    2008-01-01

    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.

  13. O mtodo WKB exposto no ltimo captulo no pode ser aplicado diretamente a sistemas genricos com mais de um grau de liberdade. A razo para isso ficar mais clara no captulo 6, onde trataremos de

    E-print Network

    de Aguiar, Marcus A. M.

    ¢¡ £¢¤¦¥§¡©¨ ¢¢ ¢¡ ©¨©§¢¢¢ ¢©¨ O método WKB exposto no último capítulo não pode ser aplicado) quanto sobre as funções de onda (os resíduos). Como discutimos no capítulo 1, G± pode ser obtida da intervalo de tempo finito pode ser expresso em termos de propagadores infinitesimais. O intervalo t é

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

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

    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.

  16. Medical application of 26Al

    NASA Astrophysics Data System (ADS)

    Hohl, Ch.; Gerisch, P.; Korschinek, G.; Nolte, E.; Ittel, T. H.

    1994-06-01

    After oral application of 100 ng of 26Al in 100 ?g, of Al as AlCl 3 to two volunteers, 26Al concentrations in blood serum and in urine were measured with accelerator mass spectrometry. Altogether 44 samples were measured in a time period of 23 days after application of 26Al. The measured data were described by an open four-compartment model. Aluminum resorption factors and rate constants for resorption, elimination and exchange between the compartments were obtained. The deduced resorption factors are in the range of 10 -3.

  17. Electron emission characteristics of Al AlN granular films

    NASA Astrophysics Data System (ADS)

    Liang, H. F.; Liu, C. L.; Liang, Z. H.; Meng, L. G.

    2008-08-01

    An electron conduction emitter of Al-AlN granular films was proposed for surface conduction electron emission device in this paper. The Al-AlN granular films with thickness of 30 nm were prepared between two co-planar electrodes with gap of 10 ?m by magnetron sputtering. After electroforming the Al-AlN granular films, the films' structure could be recovered by applying the periodic device voltage ( Vf). Stable and uniform electron emission was observed with turn-on voltage of 5.3 V and threshold voltage of 9 V. The emitter emission current ( Ie) of 4.84 ?A for 36 cells was obtained with the anode voltage of 2.5 kV and the device voltage of 12 V. In addition, Fowler-Nordheim plots for Ie- Vf properties showed that the electron emission mechanism should be field emission.

  18. Theoretical studies of AlF, AlCl, and AlBr

    NASA Technical Reports Server (NTRS)

    Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Taylor, Peter R.

    1988-01-01

    Spectroscopic constants have been obtained for the lowest six singlet and lowest five triplet states of AlF and AlCl. The results suggest that the correct ordering of the triplet manifold in these molecules is: a 3Pi, b 3Sigma(+), c 3Sigma(+), d 3Pi, and e 3Delta. Radiative lifetimes have been determined for the excited states, and the A 1Pi to X 1Sigma(+) transition in AlF, AlCl, and AlBr has been examined in detail. A-X transition moment functions, Einstein coefficients, and A 1Pi vibrational lifetimes have been obtained for AlF and AlCl.

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

    NASA Astrophysics Data System (ADS)

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

    2011-02-01

    The uniform and dense Al2O3 and Al2O3/Al coatings were deposited on an orthorhombic Ti2AlNb alloy by filtered arc ion plating. The interfacial reactions of the Al2O3/Ti2AlNb and Al2O3/Al/Ti2AlNb specimens after vacuum annealing at 750 °C were studied. In the Al2O3/Ti2AlNb specimens, the Al2O3 coating decomposed significantly due to reaction between the Al2O3 coating and the O-Ti2AlNb substrate. In the Al2O3/Al/Ti2AlNb specimens, a ?-TiAl layer and an Nb-rich zone came into being by interdiffusion between the Al layer and the O-Ti2AlNb substrate. The ?-TiAl layer is chemically compatible with Al2O3, with no decomposition of Al2O3 being detected. No internal oxidation or oxygen and nitrogen dissolution zone was observed in the O-Ti2AlNb alloy. The Al2O3/Al/Ti2AlNb specimens exhibited excellent oxidation resistance at 750 °C.

  20. Alexandria (Al Iskandariya), Egypt

    NASA Technical Reports Server (NTRS)

    2002-01-01

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

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

    SciTech Connect

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

    2009-03-03

    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.

  2. Medical application of 26Al

    NASA Astrophysics Data System (ADS)

    Steinhausen, C.; Gerisch, P.; Heisinger, B.; Hohl, Ch.; Kislinger, G.; Korschinek, G.; Niedermayer, M.; Nolte, E.; Dumitru, M.; Alvarez-Brückmann, M.; Schneider, M.; Ittel, T. H.

    1996-06-01

    Accelerator mass spectrometry (AMS) measurements with 26Al as tracer were performed in order to study the aluminium metabolism and anomalies in the human body and in rats. In particular, the differences between healthy volunteers and patients with renal failure were investigated. The obtained data points of 26Al in blood and urine were described by an open compartment model with three peripheral compartments. It was found that the minimum of peripheral compartments needed to describe 26Al concentrations in blood and urine over a time period of three years is at least three.

  3. Analisi del Lotka-Volterra

    E-print Network

    De Marchi, Stefano

    = c x(t)y(t) - d y(t) (2) a, b, c, d sono costanti reali positive. a x(t) indica fattore di crescita(t) dt = a x(t) - b x(t) y(t) (1) dy(t) dt = c x(t)y(t) - d y(t) (2) a, b, c, d sono costanti reali) a, b, c, d sono costanti reali positive. a x(t) indica fattore di crescita, mentre l'effetto delle

  4. Reply to Gopalswamy et al.

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Richardson, I. G.

    2003-01-01

    The comment of Gopalswamy et al. (thereafter GMY) relates to a letter discussing coronal mass ejections (CMEs), interplanetary ejecta and geomagnetic storms. GMY contend that Cane et al. incorrectly identified ejecta (interplanetary CMEs) and hypothesize that this is because Cane et al. fail to understand how to separate ejecta from "shock sheaths" when interpreting solar wind and energetic particle data sets. They (GMY) are wrong be cause the relevant section of the paper was concerned with the propagation time to 1 AU of any potentially geoeffective structures caused by CMEs, i.e. upstream compression regions with or without shocks, or ejecta. In other words, the travel times used by Cane et al. were purposefully and deliberately distinct from ejecta travel times (except for those slow ejecta, approx. 30% of their events, which generated no upstream features), and no error in identification was involved. The confusion of GMY stems from the description did not characterize the observations sufficiently clearly.

  5. Reply to Fischer et al.

    PubMed

    Watson, Stuart K; Townsend, Simon W; Schel, Anne M; Wilke, Claudia; Wallace, Emma K; Cheng, Leveda; West, Victoria; Slocombe, Katie E

    2015-11-01

    We welcome the correspondence from Fischer and colleagues regarding our recent paper on vocal learning in chimpanzee food grunts [1]. Fischer et al. make two challenges to our paper's conclusions, which we address here. PMID:26528741

  6. Developmental Cell Abbott et al.

    E-print Network

    Bartel, David

    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

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

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2004-01-01

    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.

  8. Descenso al Infierno de Venus Manuel Alfonseca

    E-print Network

    Alfonseca, Manuel

    Descenso 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 ........................................131 #12;Descenso al infierno de Venus 5 Tres días antes de la partida teve MacDunn no se sorprendió al

  9. Modeling of the ALS linac

    SciTech Connect

    Kim, C.H.

    1996-08-01

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

  10. Attack on Kang et al.'s Identity-Based Strong Designated Verifier Signature Scheme

    E-print Network

    International Association for Cryptologic Research (IACR)

    Attack on Kang et al.'s Identity-Based Strong Designated Verifier Signature Scheme Hongzhen Du1-mail: duhongzhen@gmail.com Abstract: In this paper, we present a universal forgery attack on Kang et al.'s identity. Moreover, we point out that Kang et al.'s scheme does not satisfy the properties of strongness and non

  11. 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

  12. Rodger et al. Data Repository

    E-print Network

    Watts, A. B. "Tony"

    , heavy grey shade = BP (P. Bentham, pers. comm., June 2004), light grey shade = Kumar et al. (1979- squared Water 1 6413 0.016 1.147 Sediment 2 270 0.015 0.968 Sediment 3 516 0.013 0.726 Sediment 4 140 0

  13. Lynch et al. Proceedings 109

    E-print Network

    Moorcroft, Paul R.

    Lynch et al. Proceedings 109 Insect­Fire Interactions in Yellowstone National Park: The Influence winds were responsible for the overall scale of the event, we concluded that mountain pine beetle insect outbreaks and forest fires constitute important disturbance processes in the Greater Yel- lowstone

  14. Als lebendige Mumie nach Berlin

    E-print Network

    Waldmann, Uwe

    Als lebendige Mumie nach Berlin Am 25. November 1915 hielt Albert Einstein vor der Preußischen Realität. Diese Erkennt- nis ist Albert Einsteins größte Leistung." Fast so erstaunlich wie das Ergebnis MaxPlanckForschung 3 | 15 Vor 100 Jahren vollendete Albert Einstein die allgemeine Relativitätstheorie

  15. Comment on Yuan et al

    E-print Network

    Fan Wang; T. Goldman

    2000-01-10

    The work of Yuan et al. (Phys. Rev. C 60 (1999) 045203) is being represented as definitive regarding the non-existence of a particular nonstrange, isoscalar, spin three dibaryon which has been proposed. We comment on this paper and its relation to our work and that of others.

  16. Dynamic Modeling of ALS Systems

    NASA Technical Reports Server (NTRS)

    Jones, Harry

    2002-01-01

    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.

  17. Response to Pagano et al.

    PubMed

    Rezende, Flávia; Löwe, Oliver; Helfinger, Valeska; Prior, Kim-Kristin; Walter, Maria; Zukunft, Sven; Fleming, Ingrid; Weissmann, Norbert; Brandes, Ralf P; Schröder, Katrin

    2015-11-20

    In their letter, Pagano et al. appreciate the development of the Nox1, Nox2, and Nox4 triple (3N(-/-)) knockout mouse. They also agree on the view that chemiluminescence assays in general have severe limitations. However, they criticize the fact that the membrane assays in the particular study were restricted to chemiluminescence techniques. Moreover, Pagano et al. got the impression that statements concerning membrane assays of Nox activity in general were made. In addition to a lack of some technical details, Pagano et al. also found the characterization of the 3N(-/-) incomplete and some of the results to be incomprehensible. Although we are grateful for the interest of Pagano et al. in our work, we realized that basically each observation of our study was questioned. This is certainly an excessive rejection of the study in total and fails to appreciate the clear chain of evidences presented. Our work focused on chemiluminescence, and thus, any conclusions are restricted to this technique. Moreover, the 3N(-/-) mice were never developed to study the physiology of Nox enzymes, but rather to validate Nox specificity of NADPH-stimulated chemiluminescence assays. We are convinced that our findings are a valid demonstration that chemiluminescence-based assays in membrane preparations stimulated with NADPH do not measure Nox activity. This conclusion is based on both overexpression studies as well as genetic deficient mouse models. The criticisms of Pagano et al. thus might be justified in some aspects; they, however, cannot disprove the conclusions of our work. Antioxid. Redox Signal. 23, 1247-1249. PMID:26173053

  18. Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions.

    PubMed

    Zhang, Kun; Li, Huan-Huan; Grünberg, Peter; Li, Qiang; Ye, Sheng-Tao; Tian, Yu-Feng; Yan, Shi-Shen; Lin, Zhao-Jun; Kang, Shi-Shou; Chen, Yan-Xue; Liu, Guo-Lei; Mei, Liang-Mo

    2015-01-01

    Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%. The findings of rectification magnetoresistance open the way to the new nonmagnetic Ge-based spintronics devices of large rectification magnetoresistance at ambient temperature under the alternating-current due to the simultaneous implementation of the rectification and magnetoresistance in the same devices. PMID:26387967

  19. Large rectification magnetoresistance in nonmagnetic Al/Ge/Al heterojunctions

    PubMed Central

    Zhang, Kun; Li, Huan-huan; Grünberg, Peter; Li, Qiang; Ye, Sheng-tao; Tian, Yu-feng; Yan, Shi-shen; Lin, Zhao-jun; Kang, Shi-shou; Chen, Yan-xue; Liu, Guo-lei; Mei, Liang-mo

    2015-01-01

    Magnetoresistance and rectification are two fundamental physical properties of heterojunctions and respectively have wide applications in spintronics devices. Being different from the well known various magnetoresistance effects, here we report a brand new large magnetoresistance that can be regarded as rectification magnetoresistance: the application of a pure small sinusoidal alternating-current to the nonmagnetic Al/Ge Schottky heterojunctions can generate a significant direct-current voltage, and this rectification voltage strongly varies with the external magnetic field. We find that the rectification magnetoresistance in Al/Ge Schottky heterojunctions is as large as 250% at room temperature, which is greatly enhanced as compared with the conventional magnetoresistance of 70%. The findings of rectification magnetoresistance open the way to the new nonmagnetic Ge-based spintronics devices of large rectification magnetoresistance at ambient temperature under the alternating-current due to the simultaneous implementation of the rectification and magnetoresistance in the same devices. PMID:26387967

  20. 76 FR 38700 - United States, et al.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-01

    ... published in the Federal Register on October 13, 2010 (75 FR 62858); and (3) published summaries of the... Antitrust Division United States, et al. v. American Express Company, et al.; Public Comments and Response... Final Judgment in United States, et al. v. American Express Company, et al., Civil Action No....

  1. (12) United States Patent Vertes et al.

    E-print Network

    Vertes, Akos

    (12) United States Patent Vertes et al. (54) LASER DESORPTION IONIZATION AND PEPTIDE SEQUENCING 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 al. 6,881,950 B2 4/2005 Schlaf et aI. 111111

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

    E-print Network

    Chi, Ji

    2009-05-15

    by specific heat measurements in Fe2Al5. Both Fe4 Al13 and Fe2Al5 are non-magnetic systems with dilute magnetic defects, while FeAl2 is a concentrated local magnetic moment system. In Al20V2Eu, a crossover was observed in NMR, magnetization and transport...

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

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

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

    SciTech Connect

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

    2011-07-15

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

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  6. United States Patent [19] Church et al.

    E-print Network

    Church, George M.

    United States Patent [19] Church et al. [54] CHARACTERIZATION OF INDIVIDUAL POLYMER MOLECULES BASED 1111111111111111111111111111111111111111111111111111111111111 US005795782A [11] Patent Number: [45] Date of Patent: 5,795,782 Aug. 18, 1998 Boulanger et al

  7. Schler et al 2001 Mycol Arbuscular mycorrhiza

    E-print Network

    California at Berkeley, University of

    ;Photo from Ann Pringle #12;From Redecker et al 2000 From Benny et al. 2001 #12;Root of Phaseolus vulgaris colonized by arbuscular mycorrhizal fungi vesicle arbuscules (c) D. Redecker 10µm #12;Auxilary

  8. New synthetic route to Al4O4C reinforced Al-Al2O3 composite materials

    NASA Astrophysics Data System (ADS)

    Jiang, Peng; Sun, Jialin; Xue, Wendong; Chen, Junhong; Vasant Kumar, R.; Li, Yong

    2015-08-01

    Carbon free Al-Al2O3 composite sliding gate materials were successfully prepared by adding excess amount of Al powders through carbon burial sintering at 1450 °C for 6 h. Physical properties including apparent porosity, bulk density, ambient temperature crushing strength and hot rupture modulus were characterized for all the samples and addition of 9 at% aluminum powder was proved to exhibit optimal properties. The XRD and SEM results reveal that Al4O4C and AlN phases shown in the product samples are serving as reinforcement phase, contributing to better physical performances.

  9. Photoelectrical, photophysical and photocatalytic properties of Al based MOFs: MIL-53(Al) and MIL-53-NH2(Al)

    NASA Astrophysics Data System (ADS)

    An, Yang; Li, Huiliang; Liu, Yuanyuan; Huang, Baibiao; Sun, Qilong; Dai, Ying; Qin, Xiaoyan; Zhang, Xiaoyang

    2016-01-01

    Two Al based MOFs (MIL-53(Al) and MIL-53-NH2 (Al)) were synthesized, and their photoelectrical, photophysical and photocatalytic properties towards oxygen evolution from water were investigated. Different from the ligand to metal charge transfer process previously reported, we proposes a new photocatalytic mechanism based on electron tunneling according to the results of theoretical calculation, steady state and time resolved fluorescence spectra. The organic linkers absorb photons, giving rise to electrons and holes. Then, the photogenerated electrons tunnel through the AlO6-octahedra, which not only inhibit the recombination of photogenerated charge carriers, but also is a key factor to the photocatalytic activity of Al based MOFs.

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

    SciTech Connect

    Ruiz-Salvador, A. Rabdel; Grau-Crespo, Ricardo; Gray, Aileen E.; Lewis, Dewi W.

    2013-02-15

    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.

  11. Nonstoichiometry of Al-Zr intermetallic phases

    SciTech Connect

    Radmilovic, V.; Thomas, G.

    1994-06-01

    Nonstoichiometry of metastable cubic {beta}{prime} and equilibrium tetragonal {beta} Al-Zr intermetallic phases of the nominal composition Al{sub 3}Zr in Al-rich alloys has been extensively studied. It is proposed that the ``dark contrast`` of {beta}{prime} core in {beta}{prime}/{sigma}{prime} complex precipitates, in Al-Li-Zr based alloys, is caused by incorporation of Al and Li atoms into the {beta}{prime} phase on Zr sublattice sites, forming nonstoichiometric Al-Zr intermetallic phases, rather than by Li partitioning only. {beta}{prime} particles contain very small amounts of Zr, approximately 5 at.%, much less than the stoichiometric 25 at.% in the Al{sub 3}Zr metastable phase. These particles are, according to simulation of high resolution images, of the Al{sub 3}(Al{sub 0.4}Li{sub 0.4}Zr{sub 0.2}) type. Nonstoichiometric particles of average composition Al{sub 4}Zr and Al{sub 6}Zr are observed also in the binary Al-Zr alloy, even after annealing for several hours at 600{degree}C.

  12. (12) United States Patent Vertes et al.

    E-print Network

    Vertes, Akos

    (12) United States Patent Vertes et al. (54) NANOPHOTONIC PRODUCTION, MODULATION AND SWITCHING to any disclaimer, the term ofthis patent is extended or adjusted under 35 U.S.c. 154(b) by 194 days. (21) References Cited U.S. PATENT DOCUMENTS 200910236512 Al * 912009 Naya et al. .................... 250/281 2009

  13. Framework Al zoning in zeolite ECR-1.

    PubMed

    Shin, Jiho; Ahn, Nak Ho; Cho, Sung June; Ren, Limin; Xiao, Feng-Shou; Hong, Suk Bong

    2014-02-25

    Rietveld analyses of the synchrotron X-ray diffraction data for various cation forms of zeolite ECR-1 have demonstrated framework Al zoning, which parallels the alternation of Al-rich maz and Al-poor mor layers. This can be further supported by notable differences in the average bond valence of its 10 crystallographically distinct tetrahedral sites. PMID:24409461

  14. Convocatoria al I Certamen de Emprendedores Cloud

    E-print Network

    Cardeñosa, Jesús

    Convocatoria al I Certamen de Emprendedores Cloud Convocante EUROCLOUD España Colaboran Madrid los Emprendedores Cloud Pedro Prestel ­ Presidente de EuroCloud España Agenda de la Convocatoria al I Certamen de Emprendedores Cloud 15.40 ­ 16.00 Recursos y Medios al Servicio del Emprendedor Fernando

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

    SciTech Connect

    Watanabe, Yoshimi; Yamanaka, Noboru; Fukui, Yasuyoshi

    1999-12-01

    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.

  16. Systems Engineering Techniques for ALS Decision Making

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

  17. Instandhaltungsmanagement als Gestaltungsfeld Ganzheitlicher Produktionssysteme

    NASA Astrophysics Data System (ADS)

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

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

  18. Supra-Canonical 26Al/27Al and the Residence Time of CAIs in the

    E-print Network

    Harrison, Mark

    initial 26Al/27Al cannot mark the beginning of solar system formation. Using rates of Mg diffusion initial 26Al/27Al ratio of 4.5 Â 10­5 has been a fiducial marker for the beginning of the solar system of heat in the early solar system (1). It is also a high-resolution chronometer for early solar system

  19. Reactive Plasma Spraying of Fine Al2O3/AlN Feedstock Powder

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  20. Reply to Vance et al.

    SciTech Connect

    Woon-Chee Yee; Elliott, J.L; Kwon, J.M.; Goodfellow, P.

    1996-07-01

    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.

  1. Toxicity of Al to Desulfovibrio desulfuricans

    SciTech Connect

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

    2003-07-02

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

  2. Growth and Stress-induced Transformation of Zinc blende AlN Layers in Al-AlN-TiN Multilayers.

    PubMed

    Li, Nan; Yadav, Satyesh K; Wang, Jian; Liu, Xiang-Yang; Misra, Amit

    2015-01-01

    AlN nanolayers in sputter deposited {111}Al/AlN/TiN multilayers exhibit the metastable zinc-blende-structure (z-AlN). Based on density function theory calculations, the growth of the z-AlN is ascribed to the kinetically and energetically favored nitridation of the deposited aluminium layer. In situ nanoindentation of the as-deposited {111}Al/AlN/TiN multilayers in a high-resolution transmission electron microscope revealed the z-AlN to wurzite AlN phase transformation through collective glide of Shockley partial dislocations on every two {111} planes of the z-AlN. PMID:26681109

  3. Growth and Stress-induced Transformation of Zinc blende AlN Layers in Al-AlN-TiN Multilayers

    PubMed Central

    Li, Nan; Yadav, Satyesh K.; Wang, Jian; Liu, Xiang-Yang; Misra, Amit

    2015-01-01

    AlN nanolayers in sputter deposited {111}Al/AlN/TiN multilayers exhibit the metastable zinc-blende-structure (z-AlN). Based on density function theory calculations, the growth of the z-AlN is ascribed to the kinetically and energetically favored nitridation of the deposited aluminium layer. In situ nanoindentation of the as-deposited {111}Al/AlN/TiN multilayers in a high-resolution transmission electron microscope revealed the z-AlN to wurzite AlN phase transformation through collective glide of Shockley partial dislocations on every two {111} planes of the z-AlN. PMID:26681109

  4. Effects of Al Contents on Carburization Behavior and Corrosion Resistance of TiAl Alloys

    NASA Astrophysics Data System (ADS)

    Liao, Cui Jiao; He, Yue Hui; Ming, Xing Zu

    2015-10-01

    TiAl alloys with Al contents of 30.7, 37, 46.5, and 54.2 at.% were carburized. Corrosion resistance of the untreated and the carburized TiAl alloys was comparatively analyzed. The phase and microstructure of the carburized TiAl alloys were studied by x-ray diffraction and scanning electron microscopy, respectively. Electrochemical corrosion behavior of the untreated and the carburized TiAl alloys was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. Experimental results indicate that different Al contents bring about distinct microstructure of the carburized layers. The lower Al content leads to the formation of the thicker binary carbides and the thinner Ti2AlC phase. Additionally, the lower Al content leads to higher corrosion resistance in the untreated and the carburized states.

  5. Chemical mixing at "Al on Fe" and "Fe on Al" interfaces

    NASA Astrophysics Data System (ADS)

    Süle, P.; Kaptás, D.; Bujdosó, L.; Horváth, Z. E.; Nakanishi, A.; Balogh, J.

    2015-10-01

    The chemical mixing at the "Al on Fe" and "Fe on Al" interfaces was studied by molecular dynamics simulations of the layer growth and by 57Fe Mössbauer spectroscopy. The concentration distribution along the layer growth direction was calculated for different crystallographic orientations, and atomically sharp "Al on Fe" interfaces were found when Al grows over (001) and (110) oriented Fe layers. The Al/Fe(111) interface is also narrow as compared to the intermixing found at the "Fe on Al" interfaces for any orientation. Conversion electron Mössbauer measurements of trilayers—Al/57Fe/Al and Al/57Fe/Ag grown simultaneously over Si(111) substrate by vacuum evaporation—support the results of the molecular dynamics calculations.

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

  7. (12) United States Patent Likourezos et al.

    E-print Network

    Shamos, Michael I.

    /1998 Mandler et al. 5,778,178 A 7/1998 Arunachalam 5,794,207 A 8/1998 Walker et al. 5,794,219 A 8/1998 Brown 5,138,106 A 1012000 Walker et al. 6,138,107 A 1012000 Elgamal 6,202,051 Bl 3/2001 Woolston 6,212,556 Bl 4,340,429 B2 3/2008 Maltzman 7,343,335 Bl 3/2008 Olliphant 7,343,339 B2 3/2008 Harrison, Jr. et al. 7

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

    NASA Astrophysics Data System (ADS)

    Pstru?, Janusz; Gancarz, Tomasz

    2014-05-01

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

  9. Growth and characterization of AlGaN/AlN/GaN/AlGaN double heterojunction structures with AlGaN as buffer layers

    NASA Astrophysics Data System (ADS)

    Peng, Enchao; Wang, Xiaoliang; Xiao, Hongling; Wang, Cuimei; Yin, Haibo; Chen, Hong; Feng, Chun; Jiang, Lijuan; Hou, Xun; Wang, Zhanguo

    2013-11-01

    High electron mobility transistors (HEMTs) structures with GaN, Al0.025Ga0.975N and Al0.04Ga0.96N high resistivity (HR) buffers were grown on sapphire by metal organic chemical vapor deposition (MOCVD). The structural and electrical properties of these three samples were investigated and compared. By increasing Al composition of AlGaN buffer, full width at half maximum (FWHM) values of (0002) and (10-12) x-ray rocking curves for buffer increase, indicating higher threading dislocation density. Room temperature noncontact Hall measurements were performed, and the measured 2DEG mobility was 1828 cm2/V s for GaN buffer, 1728 cm2/V s for Al0.025Ga0.975N buffer, and 1649 cm2/V s for Al0.04Ga0.96N buffer, respectively. Combining the theoretical calculation with the experiments, it was demonstrated that the decrease of mobility was attributed to higher dislocation density in sample with higher Al composition of AlGaN buffer. Devices were fabricated and it was found that the double heterojunction (DH) HEMT with Al0.025Ga0.975N buffer could effectively reduce the buffer leakage current.

  10. Hepatocyte growth factor measurement in AL amyloidosis.

    PubMed

    Abraham, Julie; Desport, Estelle; Rigaud, Charlotte; Marin, Benoit; Bender, Sébastien; Lacombe, Corinne; Moreau, Stéphane; Yagoubi, Fatima; Bordessoule, Dominique; Lavergne, David; Bridoux, Frank; Jaccard, Arnaud

    2015-01-01

    Hepatocyte growth factor (HGF) is a pro-angiogenic cytokine activated by tissue-type plasminogen activator (tPA) that might play a role in the progression of multiple myeloma (MM). Preliminary studies indicated that serum HGF levels were higher in patients with AL amyloidosis (AL) compared to those with MM. The aim of the present study was to determine whether HGF is a relevant marker of diagnosis and prognosis in AL. HGF serum levels were measured at diagnosis in patients with monoclonal gammopathy (MG) without AL (76 controls), or with biopsy-proven systemic AL (69 patients). HGF serum levels were significantly higher in patients with AL compared to controls, respectively, 11.2?ng/mL [min: 0.95-max: 200.4] versus 1.4?ng/mL [min: 0.82-max: 6.2] (p?AL and monoclonal gammopathy of undetermined significance (MGUS) patients. Serum HGF concentrations were correlated positively with the severity of cardiac involvement and the serum level of monoclonal light chains. These data suggest that HGF measurement could be used in patients with MG to detect AL or to reinforce a clinical suspicion of AL and to guide indications for diagnostic tissue biopsies. PMID:26053104

  11. Processing and Mechanical Properties of Directionally Solidified NiAl/NiAlTa Alloys

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    Promising creep strengths were found for a directionally solidified NiAl-NiAlTa alloy when compared to other NiAl based intermetallics. The directionally solidified alloy had an off-eutectic composition that resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of the two phase alloy was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Alloying additions that may improve the room temperature toughness by producing multiphase alloys are discussed.

  12. Preparation and Thermoelectric Properties of YbAl3 Thermoelectric Materials with Excessive Al

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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.

  13. Al-Juwayni? & Al-G?h?aza?li? as theologians : with special reference to (Al-irsha?d) & (Al-itiqa?d) 

    E-print Network

    Bisar, M. A. R.

    1953-01-01

    The aim of this thesis is to expound and compare the theological aspect of the thought of al-Juwayni? and al-G?h?aza?li?; we shall seek to discover similarities and differences between them in their methods and in their ...

  14. Durability Assessment of TiAl Alloys

    NASA Technical Reports Server (NTRS)

    Draper, Susan L.; Lerch, Bradley A.

    2008-01-01

    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.

  15. Quantitatively Probing the Al Distribution in Zeolites

    SciTech Connect

    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

    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.

  16. Diana Al-Hadid: Identity and Heritage

    ERIC Educational Resources Information Center

    Jungerberg, Tom; Smith, Anna; Borsh, Colleen

    2012-01-01

    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…

  17. Bachelorarbeit Integration von PDF-Formularen als

    E-print Network

    Bachelorarbeit Integration von PDF-Formularen als Benutzerschnittstelle von computergenerierten Aufgaben in LON-CAPA Vorgelegt von: Thomas Onken Emden, Juli 2008 Betreut von : Prof. Dr. Gerd von Cölln/Ostfriesland/Wilhemshaven Fachbereich Technik Studiengang Medientechnik Thema : Integration von PDF-Formularen als Benutzerschnittstelle

  18. (12) United States Patent Happer et al.

    E-print Network

    Romalis, Mike

    (12) United States Patent Happer et al. US006318092B1 (10) Patent N0.: (45) Date of Patent: US 6 (US) ( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35) References Cited U.S. PATENT DOCUMENTS 4,450,407 5/1984 Kwon et al. ......................... 324/304 4

  19. Al-26 in the interstellar medium

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1984-01-01

    The amount of dispersed interstellar Al-26 detected by the HEAO 3 gamma-ray spectrometer cannot have been synthesized by supernova explosions if current calculations of the production ratio p(26)/p(27) approximately equal to 0.001 are correct. Simple models of chemical evolution of the Galaxy are presented to explain this point. The observed Al-26 is more likely due to about 100 million dispersed novae, or to a single old (10,000-1,000,000 yr) supernova remnant that today surrounds the solar system. If the Al-26 is dispersed, the high interstellar ratio today Al-26/Al-27 about equal to 0.00002 calls into question the requirement that a supernova trigger for formation of the solar system was the cause of a concentration 3-times larger. Also discussed is p-process production in novae with application to the question of live Sm-146 in the solar system.

  20. NiAl alloys for structural uses

    NASA Technical Reports Server (NTRS)

    Koss, D. A.

    1991-01-01

    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.

  1. Opportunities for improving therapy development in ALS.

    PubMed

    Bruijn, Lucie; Cudkowicz, Merit

    2014-06-01

    In May 2013, The ALS Association and The Northeast ALS Consortium (NEALS) convened a meeting of stakeholders for a round-table discussion of ways to improve therapy development in ALS. The following overview summarizes issues raised and potential new directions discussed at the meeting. We recommend that future phase II clinical trials in ALS proceed when the proposed treatment is directed at targets that are likely to be involved in ALS pathogenesis in a defined subgroup of patients, and be accompanied by one or more biomarkers to track both clinical progression and pharmacodynamic engagement of the target. Innovations in trial structure and design, and greater involvement of patient advocates, may also improve trials. PMID:24472060

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    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.

  4. 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

    2012-12-11

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

  5. Boston University AccelerAted MedicAl And dentAl ProgrAMs

    E-print Network

    or a foreign language. Please photocopy this form and distribute it to those teachers. Please check the subject area of the teacher completing this form: English History Foreign Language Laboratory Science NameBoston University AccelerAted MedicAl And dentAl ProgrAMs teAcher evAlUAtion To the applicant

  6. Phase periodic conductance oscillations at subgap Andreev resonances in Nb-Al-AlOx-Al-Nb tunnel junctions

    NASA Astrophysics Data System (ADS)

    Senapati, Kartik; Blamire, Mark G.; Barber, Zoe H.

    2010-10-01

    We show evidence of a magnetic field dependent oscillation of subgap dynamic conductivity in a series of Nb-Al-AlOx-Al-Nb Josephson tunnel junctions in the voltage biased state. Our measurements show that the amplitude of conductance oscillations was maximum close to the subharmonic conductance peaks of the junctions, which are collective resonances of multiple Andreev reflected quasiparticles via pinholes in the tunnel barrier. The period of oscillations was commensurate with the macroscopic phase evolution of the junction. This observation suggests that under certain conditions practical Josephson tunnel junctions are analogous to Andreev interferometers, where the junction itself acts as the flux quantizer.

  7. Lo sviluppo della teoria perturbativa nella Meccanica contemporanea

    E-print Network

    Roma "La Sapienza", Università di

    ad un #12;sico quale l' autore di questa nota). Il sistema con " = 0 #18;e semplicemente descritto da a lungo, di problemi assai interessanti per l' Analisi, l' Analisi armonica, il Calcolo delle Probabilit; =! _ B = : : : (1:2) e appunto si vede che al tempo t l' angolo #12; #18;e #12;(t) = #12;(0)+!t, dando

  8. Effects of hydrogen absorption in TbNiAl and UNiAl

    SciTech Connect

    Bordallo, H.N.; Nakotte, H.; Schultz, A.; Kolomiets, A.V.; Havela, L.; Andreev, A.V.

    1998-12-31

    Although hydrides of intermetallic compounds are used extensively as hydrogen-storage media, little is known about the exact nature of metal-hydrogen interactions. However, this knowledge is of essential importance for the understanding of thermodynamics and other properties. Hydrides (deuterides) of TbNiAl and UNiAl have been widely studied because of drastic increase of magnetic ordering temperature under hydrogenation. Here the authors report neutron-diffraction results of the three deuterides, TbNiAlD{sub 1.28}, TbNiAlD{sub 0.8}a nd UNiAlD{sub 2.23}.

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

    SciTech Connect

    Choquette, K.D.; Geib, K.M.; Hou, H.Q.; Lear, K.L.; Chui, H.C.; Hammons, B.E.; Nevers, J.A.; Hull, R. |

    1996-12-01

    Buried oxides formed from the wet oxidation of AlGaAs alloys, rather than AlAs, are found to be superior in terms of oxidation isotropy, mechanical stability, and strain. It is not surprising that vertical-cavity surface-emitting lasers (VCSELs) using AlGaAs oxide layers as current apertures have shown promising reliability as compared to VCSELs using AlAs layers. Comparisons of lifetime data for VCSELs with differing oxide layers is presented. The beneficial properties of oxides converted from AlGaAs alloys are found to provide robust device processing of reliable VCSELs and may play an important role in other advanced optoelectronic devices.

  10. Atomistic Modeling of RuAl and (RuNi) Al Alloys

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  11. Reaction of Ti and Ti-Al alloys with alumina

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1991-01-01

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

  12. Suspected variables among Al Sufi stars.

    NASA Astrophysics Data System (ADS)

    Hoffleit, D.

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

  13. [A strategy to develop effective ALS therapy].

    PubMed

    Mitsumoto, Hiroshi

    2007-04-01

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

  14. Effect of AL on Electric Conductivity and Superconductivity of NB-Si-AL-O Ceramic

    NASA Astrophysics Data System (ADS)

    Koba, S.; Higo, S.; Hakuraku, Y.; Kawano, I.; Ogushi, T.; Nakao, A.

    Metal-insulator transition and superconductivity with changing Al composition were observed in the Nb-Si-Al-O system. Semiconductor-like characteristic and normal conductive characteristic were observed for Al<40% and Al>50% respectively. Super-conductive compositions are distributed around the boundary between those two types of conductivity, such as NbxSiAl(?-x)Oz((?, x)=(1.5, 0.7), (2.0,0.8), (3.0, 0.7~1.4)). The superconductivity was confirmed by resistive transitions and diamagnetic transitions. The superconductors in this study have Tc=10.0~11.5 K with resistive transitions, and the amplitudes of the diamagnetism reach 30~58% of that of pure Nb powder. X-ray diffraction patterns of any other superconducting Nb-systems such as Nb, Nb3Al, Nb3Si, NbN, and NbC, have not been observed in Nb-Si-Al-O.

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

    SciTech Connect

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

    2009-11-01

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

  16. Electroforming and Ohmic contacts in Al-Al2O3-Ag diodes

    NASA Astrophysics Data System (ADS)

    Hickmott, T. W.

    2012-03-01

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

  17. Gaudreault et al. (2012) critical movements subset

    E-print Network

    Najmanovich, Rafael

    2012-01-01

    Gaudreault et al. (2012) critical movements subset Holo and apo structures in PDB format Addition) Input for rDock (FLRP/FLFP) Extraction of the ligands from the holo structures Conversion to MOL2 format

  18. Thermal Conductivity of Al-Salt Composites

    NASA Astrophysics Data System (ADS)

    Li, Peng; Zhang, Mei; Wang, Lijun; Seetharaman, Seshadri

    2015-08-01

    With a view to examine the possibility of estimating the content of entrapped metallic aluminium in the salt cake from aluminium remelting, the thermal diffusivity of reference composites of KCl-NaCl-Al was measured as a function of aluminium metal content at room temperature. The thermal conductivity of the reference composites was found to increase with the metallic Al content. The lumped parameter model approach was carried out to discuss the influence of different geometry arrangements of each phase, viz. air, salts and metallic aluminium on the thermal conductivity. Application of the present results to industrial samples indicates that factors such as the interfacial condition of metallic Al particles have to be considered in order to estimate the amount of entrapped Al in the salt cake.

  19. ALS and Oxidative Stress: The Neurovascular Scenario

    PubMed Central

    Thakur, Keshav; Gupta, Pawan Kumar

    2013-01-01

    Oxidative stress and angiogenic factors have been placed as the prime focus of scientific investigations after an establishment of link between vascular endothelial growth factor promoter (VEGF), hypoxia, and amyotrophic lateral sclerosis (ALS) pathogenesis. Deletion of the hypoxia-response element in the vascular endothelial growth factor promoter and mutant superoxide dismutase 1 (SOD1) which are characterised by atrophy and muscle weakness resulted in phenotype resembling human ALS in mice. This results in lower motor neurodegeneration thus establishing an important link between motor neuron degeneration, vasculature, and angiogenic molecules. In this review, we have presented human, animal, and in vitro studies which suggest that molecules like VEGF have a therapeutic, diagnostic, and prognostic potential in ALS. Involvement of vascular growth factors and hypoxia response elements also highlights the converging role of oxidative stress and neurovascular network for understanding and treatment of various neurodegenerative disorders like ALS. PMID:24367722

  20. AL Amyloidosis Complicated by Persistent Oral Bleeding

    PubMed Central

    Marconcini, Luiz Antonio Liarte; Stewart, Forrest Marc; Sonntag, Lisa; Stevens, Emily; Burwick, Nicholas

    2015-01-01

    A case of amyloid light chain (AL) amyloidosis is presented here with uncontrolled bleeding after a nonsurgical dental procedure, most likely multifactorial in nature, and consequently treated with a multidisciplinary approach. PMID:26064714

  1. Everyday Life with ALS: A Practical Guide

    MedlinePLUS

    ... the entire guidebook Introduction Receiving a diagnosis of amyotrophic lateral sclerosis (ALS) will unquestionably alter your life in almost ... resources on a wide range of topics. Books Amyotrophic Lateral Sclerosis: A Guide for Patients and Families, 3rd edition , ...

  2. Glial cells in ALS: the missing link?

    PubMed

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

    2008-08-01

    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

  3. Al Direttore Generale Sapienza Universit di Roma

    E-print Network

    Di Pillo, Gianni

    di lavoro da tempo pieno a tempo parziale. Il sottoscritto a tempo parziale con prestazione lavorativa pari al .....................% a decorrere dal giorno ..................... In particolare opta per* (barrare una sola casella): TEMPO PARZIALE ORIZZONTALE Tabella 1 ­ Tipologia n

  4. Building Reconstruction from ALS: Integrating Shape knowledge

    E-print Network

    Building Reconstruction from ALS: Integrating Shape knowledge and Manual Operation Biao Xiong George Vosselman #12;Introduction Primitive Buildings Constraint Least Square Fit Manual Operation Future work 2 #12;Introduction Primitive Buildings Building Knowledge Constraint Least Square Fit Manual

  5. Fabrication studies of Nb3Al superconductors.

    NASA Technical Reports Server (NTRS)

    Worzala, F. J.; Yang, W. J.; Boom, R. W.; Strauss, B. P.; Laurence, J.

    1972-01-01

    Study aimed at developing fabrication techniques for the production of stabilized conductors containing both binary and ternary intermetallics of the Nb-Al system. Processes are described that offer a foundation for practical fabricating techniques suitable for the production of long lengths of stabilized Nb3Al superconductor. Once the parameters are optimized, it is conceivable that multistrand twisted composites of both binary and ternary intermetallics should become feasible.

  6. Modeling of precipitation in Al alloys

    SciTech Connect

    Asta, M.; Foiles, S.M.; Wolfer, W.G.

    1996-10-01

    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.

  7. Excitotoxicity in ALS: Overstimulation, or overreaction?

    PubMed

    King, Anna E; Woodhouse, Adele; Kirkcaldie, Matthew T K; Vickers, James C

    2016-01-01

    Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disease that results in motor dysfunction and death, generally from respiratory failure. 90% of ALS cases are sporadic with no known cause. Familial cases have been linked with mutations in several disparate classes of genes, including those involved in DNA/RNA metabolism, protein misfolding, oxidative stress and the cytoskeleton, leading to the proposition that ALS could be a multi-factorial disease. However, alterations in excitability have been reported in all types of ALS cases, and may be a common disease mechanism predisposing neurons to degeneration. Excitotoxicity has long been suspected as a mediator in the disease process, and may arise from changes in synaptic inputs, or alterations in the excitability of the neurons being stimulated. Although the glutamatergic system is widely recognised as a therapeutic avenue with the potential to extend lifespan and delay disease onset, the causes of altered excitability in ALS are currently unclear and warrant further investigation. This article reviews current evidence of alterations to excitatory and inhibitory signalling in the cortex and spinal cord, and in the intrinsic excitability of motor neurons, in ALS. PMID:26584004

  8. Metastability in the MgAl2O4-Al2O3 System

    SciTech Connect

    Wilkerson, Dr. Kelley R.; Smith, Jeffrey D; Hemrick, James Gordon

    2014-01-01

    Aluminum oxide must take a spinel form ( -Al2O3) at elevated temperatures in order for extensive solid solution to form between MgAl2O4 and -Al2O3. The solvus line between MgAl2O4 and Al2O3 has been dened at 79.6 wt% Al2O3 at 1500C, 83.0 wt% Al2O3 at 1600C, and 86.5 wt% Al2O3 at 1700C. A metastable region has been dened at temperatures up to 1700C which could have signicant implications for material processing and properties. Additionally, initial processing could have major implications on nal chemistry. The spinel solid solution region has been extended to form an innite solid solution with Al2O3 at elevated temperatures. A minimum in melting at 1975C and a chemistry of 96 wt% Al2O3 rather than a eutectic is present, resulting in no eutectic crystal formation during solidication.

  9. Thermal Properties in the MgAl2O4-Al2O3 System

    SciTech Connect

    Wilkerson, Dr. Kelley R.; Smith, Jeffrey D; Hemrick, James Gordon

    2013-01-01

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

  10. Lowest ionization potentials of Al2

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    Potential curves for the lowest two electronic states, X 2Sigma(+)g and A 2Pi(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 2Sigma(+)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 2Pi(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 3Sigma(-)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 3Pi(u).

  11. The lowest ionization potentials of Al2

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    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)

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

    SciTech Connect

    S.H.Zhou; R.E. Napolitano

    2007-06-01

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

  14. Al3AuIr: A New Compound in the Al-Au-Ir System.

    PubMed

    Kadok, Joris; de Weerd, Marie-Cécile; Boulet, Pascal; Gaudry, Émilie; Grin, Yuri; Fournée, Vincent; Ledieu, Julian

    2015-08-17

    A new ternary phase with a composition of Al3AuIr has been found in the Al-rich area of the Al-Au-Ir system. Differential thermal analysis indicates a melting point of 990 °C, and single-crystal X-ray diffraction measurements reveal that this ternary phase adopts a Ni2Al3 structure type (space group P3?m1) with a = 4.2584(5) Å and c = 5.1991(7) Å. This compound is isostructural to the Al3Cu1.5Co0.5 phase also found in the Al-rich part of the Al-Cu-Co ternary diagram. Experimental evidence combined with ab initio calculations point toward an Al3AuIr phase stabilized by a Hume-Rothery mechanism. Quantum chemical calculations indicate two-center and multicenter interactions in the Al3AuIr phase. Layered distribution of two-center interactions separated by regions with four- and five-center bonds suggests a preferential cleavage of the material at puckered planes perpendicular to the [001] direction. PMID:26241194

  15. The Dissociation Energies of AlH2 and AlAr

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Partridge, Harry; Bauschlicher, Charles W., Jr.; Visscher, Luuk; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    The D(sub 0) values for AlH2 and AlAr are computed using the coupled cluster approach in conjunction with large basis sets. Basis set superposition and spin-orbit effects are accounted for as they are sizeable due to the small binding energy. The computed dissociation energy for AlAr is 101 /cm , which is 83% of the experimental value (122.4/ cm). Our best estimate for the H2 binding energy in AlH2 is 40 +/- 28 /cm.

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

    SciTech Connect

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

    1995-04-14

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

  17. Fabrication of SiC-Particles-Shielded Al Spheres upon Recycling Al/SiC Composites

    NASA Astrophysics Data System (ADS)

    Madarasz, D.; Budai, I.; Kaptay, G.

    2011-06-01

    Wettability of liquid A359 alloy on SiC particles under molten salt NaCl-KCl-NaF is found at 180 deg, meaning that SiC particles prefer the molten salt phase against the Al phase or the Al/molten salt interface. Thus, this molten salt can be used for recycling, i.e., to separate the phases in the SiC reinforced Al matrix composites. If the separation process is interrupted, Al droplets (submillimeter solidified powder) can be produced, stabilized/surrounded by a monolayer of shielding SiC particles.

  18. Some reactive processing aspects of high-temperature aluminides Nb3Al and RuAl

    NASA Astrophysics Data System (ADS)

    Mohamed, K. E.; Stover, D.; Buchkremer, H. P.

    1997-12-01

    In the present investigation elemental powder mixtures with nominal composition of Nb-25at. % Al and Ru-50at.% Al corresponding to Nb3Al and RuAl intermetallic phases were prepared. Green compacts from these mixtures were reactive sintered in vacuum or hot isostatically pressed after being encapsulated and reacted in quartz capsules. In the absence of pressure, reactive sintering at temperatures up to 1800 °C did not lead to densification, and swelling effects were observed. Reactions of formation of Nb3Al and RuAl were found to take place at different temperature regions characteristic for each aluminide system, with clear dependence of the reaction temperature on the heating rate of the powder mixtures. Dilatometry studies showed that swelling occurred instantaneously at temperatures corresponding to the reaction temperature and led to a volume increase of about 25% and 42% for Nb3Al and RuAl, respectively. The activation energy for the reactions was estimated from the differential thermal analysis. Similar data for the NiAl intermetallic phase were also obtained for comparison. The densification behavior and the phase composition of the reaction products were investigated and correlated with the heating rate, the mutual solubility of the reactants, and the amount of liquid phase available during the reaction.

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

    SciTech Connect

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

    1999-07-01

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

  20. High temperature deformation of NiAl and CoAl

    NASA Technical Reports Server (NTRS)

    Nix, W. D.

    1982-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Mubarak, A. A. Karim; Alelaimi, Mahmoud

    2014-04-01

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

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

    E-print Network

    Neumark, Daniel M.

    with size within a cluster series, with the exception of Al5O5 . 1. Introduction Amorphous aluminum oxide present additional studies of this type, covering AlxOy À clusters with as many as seven aluminum atoms Laboratory, Berkeley, CA 94720, USA Received 17th July 2003, Accepted 27th August 2003 First published

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

    SciTech Connect

    Kim, S.M.; Morris, D.G.

    1998-05-01

    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.

  4. Heteroepitaxy of AlGaN on bulk AlN substrates for deep ultraviolet light emitting diodes

    E-print Network

    Davitt, Kristina

    Heteroepitaxy of AlGaN on bulk AlN substrates for deep ultraviolet light emitting diodes Z. Ren, Q report the growth of AlGaN epilayers and deep ultraviolet UV light emitting diodes LEDs on bulk Al optoelectronics. © 2007 American Institute of Physics. DOI: 10.1063/1.2766841 Most of AlGaN deep ultraviolet 300

  5. In their commentary, Hare et al. (2003, this issue; here-after Hare et al.) critique two recent publications reporting

    E-print Network

    Mateo, Jill M.

    In their commentary, Hare et al. (2003, this issue; here- after Hare et al.) critique two recent-discrimination abilities of these fostered animals as adults. Hare et al. comment on selected portions of issues we raised in our "Discus- sion," and we take the opportunity to respond to those comments here. Hare et al.'s main

  6. The new structure type Gd3Ni7Al14.

    PubMed

    Pukas, Svitlana; Gladyshevskii, Roman

    2015-11-01

    The crystal structure of Gd3Ni7Al14 (trigadolinium heptanickel tetradecaaluminide) belongs to a family of two-layer structures and can be described as an assembly of interpenetrating centred straight prisms. For the Ni atoms, trigonal prisms (Al4Gd2 and Al6) are observed, the Al atoms are inside tetragonal (Ni2Al2Gd4, Ni2Al4Gd2, Al4Gd4, Ni4Al4 and Al8) and pentagonal (Ni4Al6 and Al10) prisms, while the Gd atoms are at the centres of pentagonal (Ni4Al6) and hexagonal (Ni4Al8) prisms. In each case, the true coordination polyhedron is a capped prism, also including atoms from the same layer. The structural features of Gd3Ni7Al14 are similar to those of the intermetallides PrNi2Al3 and ZrNiAl. In all these structures, Ni-centred trigonal prisms form infinite columns via common triangular faces. The columns share prism edges and form a three-dimensional framework with six-membered rings in the (001) plane in the case of the PrNi2Al3 and ZrNiAl types. In the case of Gd3Ni7Al14, six-membered rings are also observed, but only two-thirds of the rings are interconnected via prism edges. PMID:26524174

  7. Combustion synthesis of TiAl-matrix composites in the Ti-Al-BN system

    SciTech Connect

    Mabuchi, H.; Tsuda, H.; Nakayama, Y. . Dept. of Metallurgy and Materials Science)

    1995-01-15

    The intermetallic compound TiAl has attracted much attention for its potential use as a structural high-temperature material. However, its use has been limited because of its negligible low-temperature ductility and fracture toughness and low high-temperature strength and creep. To improve these properties, recently this compound has been made as a composite material containing a secondary phase such as boride, carbide, nitride, or oxide. Recently, combustion synthesis or self-propagating, high-temperature synthesis (SHS) using powder compacts has been developed to produce intermetallics or ceramics. It is also possible to form intermetallic-intermetallic, intermetallic-ceramic, or ceramic-ceramic composites from combustion reactions between corresponding elemental constituents. It has the advantage of an in-situ forming technique compared with conventional artificial composite production approaches. In the previous studies using elemental powders, combustion reaction was carried out to form intermetallic-ceramic composites in the Ti-Al-C, or Ti-Al-N system. The compacts of Ti and Al powders with carbon powder or in gaseous nitrogen reacted exothermically, and formed a mixture product which had a fine distribution of the Ti[sub 2]AlC or Ti[sub 2]AlN particles in the matrix TiAl with a small amount of Ti[sub 3]Al. The processing technique, therefore, is of interest as a combustion reaction synthesis to make in-situ intermetallic-based composite materials. In the present work, to investigate the effect of BN addition on the reaction of Ti And Al powder mixtures, combustion synthesis of TiAl-matrix composites has been performed for the Ti-Al-BN system.

  8. Stress granules as crucibles of ALS pathogenesis

    PubMed Central

    King, Oliver D.

    2013-01-01

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

  9. ANALISI MATEMATICA 1 LETTURE DI ARGOMENTO MATEMATICO

    E-print Network

    Serapioni, Raul

    ) Donald O'Shea: La congettura di Poincar´e, Rizzoli, Milano 2007 (12) Simon Singh: L'ultimo Teorema di. Storia della Matematica - UTET, Torino 2006 (2) Keith Devlin: La lettera di Pascal. Storia dell

  10. Analisis fotometrico del cumulo abierto NGC 6611

    NASA Astrophysics Data System (ADS)

    Suarez Nunez, Johanna

    Matlab programs were designed to apply differential aperture photometry. Two images were taken with a charge-couple device ( CCD ) in the visible V and blue filters, to calculate physical parameters (the flux( f ), the apparent magnitude ( m V ) and its reddening corrected value ( V 0 ), color index ( B- V ) and ( B-V ) 0 , the log of effective temperature (log T eff ), the absolute magnitude ( M V ), the bolometric magnitude ( M B ) & log(L [low *] /[Special characters omitted.] )) of each studied star pertaining to the open cluster NGC 6611. Upon obtaining the parameters, the color-magnitude diagram was graphed and by fitting to the main sequence, the distance modulus and thus the distance to the cluster was found. The stars were assumed to be at the same distance and born at approximately the same moment.

  11. Analisis evolutivo del cumulo abierto NGC2527

    NASA Astrophysics Data System (ADS)

    Lovos, F.; Gonzalez, J. F.; Veramendi, M. E.

    We present a spectroscopic analysis of 13 (V ) stars in the open cluster NGC2527. We carried out a study of radial velocity variability and kinematic membership. We detected three double-lined spectroscopic binaries; two of which are cluster members. One of the binaries is a blue straggler; for which we discuss possible formation scenarios. We conclude that this system would have been formed dynamically through a binary-binary or binary-single encounter; being the blue straggler the result of the merger of the companions of the original binary. FULL TEXT IN SPANISH

  12. [Al-Biruni--a universal scientist].

    PubMed

    Kujundzi?, E; Masi?, I

    1999-01-01

    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

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

    E-print Network

    Hebard, Arthur F.

    capacitors Guneeta Singh-Bhalla, Xu Du, and Arthur F. Hebarda) Department of Physics, University of Florida-film capacitor structures. For sufficiently thin dielectrics, we find that a significant portion of the measured,7,8 characteriza- tion of metal­AlOx ­silicon capacitors,9 and for field-effect gating of conducting oxides5

  14. Experimental Neurology -Rapid Communication Panuccio et al. Rapid communication

    E-print Network

    Pineau, Joelle

    Experimental Neurology - Rapid Communication Panuccio et al. 1 Rapid communication ADAPTIVE CONTROL. #12;Experimental Neurology - Rapid Communication Panuccio et al. 2 Introduction Epilepsy is a highly

  15. Nb3Al Development for HEP Applications

    NASA Astrophysics Data System (ADS)

    Sumption, M. D.; Wu, X.; Buta, F.; Tomsic, M.; Phillips, J.; McFadden, K.; Collings, E. W.

    2004-06-01

    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.

  16. Low Temperature Studies of Fe-Al and Ni-Al Mixed Oxide Nanoparticles

    E-print Network

    Jackson, Sophie

    a resin-gel method. It was expected that Fe/Al and Ni/Al would form a defect spinel dispersive X-ray spectroscopy (EDS). Figure 1. The spinel structure1 , viewed down % Fe contained peaks corresponding to the spinel structure. Samples with over 80% Fe

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

    NASA Astrophysics Data System (ADS)

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

    2009-08-01

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

  18. Cryptanalysis of Sood et al.'s Authentication Scheme using Smart Cards

    E-print Network

    International Association for Cryptologic Research (IACR)

    Cryptanalysis of Sood et al.'s Authentication Scheme using Smart Cards Rafael Martínez-Peláez a, stolen smart card attack, off-line ID guessing attack, impersonation attack, and server spoofing attack-based; Cryptanalysis; Network Security; Smart Cards 1. Introduction The most popular mechanism to carry out the user

  19. The semi-experimental equilibrium structures of AlCCH and AlNC

    NASA Astrophysics Data System (ADS)

    Mück, Leonie Anna; Thorwirth, Sven; Gauss, Jürgen

    2015-05-01

    Based on experimental rotational constants available in the literature (Walker and Gerry, Chem. Phys. Lett. 278, 9 (1997); Walker et al., J. Mol. Spectrosc. 209, 178 (2001); Sun et al., Chem. Phys. Lett. 553, 11 (2012)) [14,17,19] for five isotopologues of AlCCH and three isotopologues of AlNC as well as quantum-chemical computations for the vibrational corrections to rotational constants, the semi-experimental structures of these two aluminum compounds are determined. These empirical equilibrium structures (AlCCH: re (Alsbnd C) = 1.957 Å, re (Csbnd C) = 1.222 Å, re (Csbnd H) = 1.065 Å; AlNC: re (Alsbnd N) = 1.850 Å, re (Nsbnd C) = 1.181 Å) compare favorably with theoretical best-estimate structures obtained using highly accurate coupled-cluster calculations in combination with sophisticated extrapolation and additivity schemes, i.e., the deviations are smaller than 0.002 Å, but significant deviations are noted in comparison with previously determined experimental structures. Good agreement is also reached between calculations and experimental values for the relevant spectroscopic parameters of AlCCH and AlNC, indicating the predictive power of state-of-the-art high-level quantum-chemical calculations.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  1. Electronic states and spin-forbidden cooling transitions of AlH and AlF.

    PubMed

    Wells, Nathan; Lane, Ian C

    2011-11-14

    The feasibility of laser cooling AlH and AlF is investigated using ab initio quantum chemistry. All the electronic states corresponding to the ground and lowest two excited states of the Al atom are calculated using multi-reference configuration interaction (MRCI) and the large AV6Z basis set for AlH. The smaller AVQZ basis set is used to calculate the valence electronic states of AlF. Theoretical Franck-Condon factors are determined for the A(1)?? X(1)?(+) transitions in both radicals and found to agree with the highly diagonal factors found experimentally, suggesting computational chemistry is an effective method for screening suitable laser cooling candidates. AlH does not appear to have a transition quite as diagonal as that in SrF (which has been laser cooled) but the A(1)?? X(1)?(+) transition transition of AlF is a strong candidate for cooling with just a single laser, though the cooling frequency is deep in the UV. Furthermore, the a(3)?? X(1)?(+) transitions are also strongly diagonal and in AlF is a practical method for obtaining very low final temperatures around 3 ?K. PMID:21842049

  2. I have never touched her: the body in Al-Ghazal Al-‘Udhri 

    E-print Network

    Alharthi, Jokha Mohammed

    2011-02-09

    Al-ghazal al-‘udhri emerged as a remarkable literary genre in Arabic literature during the Umayyad period (7th-8th centuries CE). The leaders of this genre are famous poet-lovers who were known for their dramatic love ...

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

    SciTech Connect

    Rounaghi, S.A.; Eshghi, H.; Kiani Rashid, A.R.; Vahdati Khaki, J.; Samadi Khoshkhoo, M.; Scudino, S.; Eckert, J.; TU Dresden, Institut fuer Werkstoffwissenschaft, Dresden D-01062

    2013-02-15

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

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

    ERIC Educational Resources Information Center

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

    2008-01-01

    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…

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

    DOEpatents

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

    1999-01-01

    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.

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

    ERIC Educational Resources Information Center

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

    2005-01-01

    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…

  7. Directional Solidification and Mechanical Properties of NiAl-NiAlTa Alloys

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

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

    SciTech Connect

    Kingsley, L.M.

    1980-04-01

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

  9. Superconducting properties of nanocrystalline Nb3Al in Nb-Al matrix

    NASA Astrophysics Data System (ADS)

    Mondal, Puspen; Manekar, Meghmalhar; Kumar, Ravi; Ganguli, Tapas; Roy, S. B.

    2008-02-01

    We present the results of x-ray diffraction and magnetization measurements on the nanocrystalline as-cast compound Nb3Al. X-ray diffraction shows the presence of the A15 Nb3Al phase embedded in a matrix of a bcc Nb-Al solid solution. The average grain size of Nb3Al estimated from the line broadening is about 35nm. Magnetization measurements give a lower limit of the superconducting transition temperature to be about 16.8K, which is amongst the highest known TC for the as-cast sample of Nb3Al. In the superconducting state, the sample shows anomalous thermomagnetic history effects in the temperature and field variation of magnetization.

  10. CVD Fiber Coatings for Al2O3/NiAl Composites

    NASA Technical Reports Server (NTRS)

    Boss, Daniel E.

    1995-01-01

    While sapphire-fiber-reinforced nickel aluminide (Al2O3/NiAl) composites are an attractive candidate for high-temperature structures, the significant difference in the coefficient of thermal expansion between the NiAl matrix and the sapphire fiber creates substantial residual stresses in the composite. This study seeks to produce two fiber-coating systems with the potential to reduce the residual stresses in the sapphire/NiAl composite system. Chemical vapor deposition (CVD) was used to produce both the compensating and compliant-fiber coatings for use in sapphire/NiAl composites. A special reactor was designed and built to produce the FGM and to handle the toxic nickel precursors. This process was successfully used to produce 500-foot lengths of fiber with coating thicknesses of approximately 3 microns, 5 microns, and 10 microns.

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

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

  12. 26Al+ p elastic and inelastic scattering reactions and galactic abundances of 26Al

    SciTech Connect

    Pittman, S. T.; Bardayan, Daniel W; Chae, K. Y.; Chipps, K.; Jones, K. L.; Kozub, R. L.; Matei, Catalin; Matos, M.; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Pain, Steven D; Parker, P.D.; Peters, W. A.; ShrinerJr., J. F.; Smith, Michael Scott

    2012-01-01

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

  13. Alloy inhomogeneity and carrier localization in AlGaN sections and AlGaN/AlN nanodisks in nanowires with 240–350?nm emission

    SciTech Connect

    Himwas, C.; Hertog, M. den; Dang, Le Si; Songmuang, R.; Monroy, E.

    2014-12-15

    We present structural and optical studies of AlGaN sections and AlGaN/AlN nanodisks (NDs) in nanowires grown by plasma-assisted molecular beam epitaxy. The Al-Ga intermixing at Al(Ga)N/GaN interfaces and the chemical inhomogeneity in AlGaN NDs evidenced by scanning transmission electron microscopy are attributed to the strain relaxation process. This interpretation is supported by the three-dimensional strain distribution calculated by minimizing the elastic energy in the structure. The alloy inhomogeneity increases with the Al content, leading to enhanced carrier localization signatures in the luminescence characteristics, i.e., red shift of the emission, s-shaped temperature dependence, and linewidth broadening. Despite these effects, the emission energy of AlGaN/AlN NDs can be tuned in the 240–350?nm range with internal quantum efficiencies around 30%.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2008-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Copeland, Evan

    2008-01-01

    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.

  17. 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

  18. (12) United States Patent Bauer et al.

    E-print Network

    Shamos, Michael I.

    (12) United States Patent Bauer et al. (54) APPARATUS FOR INTERNET ON-LINE INSURANCE POLICY SERVICE) Assignee: Progressive Casualty Insurance Company, Mayfield Village, OH (US) Notice: Subject to any disclaimer, the tenn of this patent is extended or adjusted under 35 U.S.c. 154(b) by 0 days. Appl. No.: 09

  19. Conetta et al Audio Engineering Society

    E-print Network

    Jackson, Philip JB

    the reference and impaired items' in an audio system [ITU-R BS.1534, 2001], `spatial quality' is defined hereConetta et al Audio Engineering Society Convention Paper Presented at the 125th Convention 2008. Additional papers may be obtained by sending request and remittance to Audio Engineering Society, 60 East 42

  20. Hughes et al.: Science or Promotion?

    ERIC Educational Resources Information Center

    Loman, L. Anthony; Siegel, Gary L.

    2013-01-01

    The Hughes et al. paper is critiqued generally and in specific areas. The weak nature of the authors' empirical work is discussed along with their enigmatic writing and vague and incorrect use of references, and their simultaneous use of sweeping statements of opinion and narrow analytical focus. This review examines the authors' errors…

  1. Joint SSRTNet/ALS-MES Workshop report

    SciTech Connect

    Shuh, David; Van Hove, Michel

    2001-11-30

    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.

  2. Masucci et al. Optimal Blockwise Subcarrier Allocation

    E-print Network

    Fijalkow, Inbar

    offset (CFO), we observe the robustness of the proposed blockwise allocation policy to the CFO effects], [7]. CFO is responsible for the loss of orthogonality among #12;Masucci et al. Page 2 of 23). In this work, we show that the SC-FDMA uplink systems without CFO and with imposed independent subcarriers

  3. Bierman {ital et al.}Reply:

    SciTech Connect

    Bierman, J.D.; Chan, P.; Liang, J.F.; Kelly, M.P.; Sonzogni, A.A.; Vandenbosch, R.

    1997-05-01

    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}

  4. Low cost, reliable ALS turbopump concept

    SciTech Connect

    Csomor, A.

    1989-01-01

    An empirical perspective is presented on the cost structure of past and current turbomachinery for liquid rocket engine turbopumps. The issues which must be addressed in the development of turbopumps for the Advanced Launch System (ALS) at an order of magnitude lower recurring cost than for present hardware are discussed. An approach proposed to attain reliability and cost objectives is outlined.

  5. (12) United States Patent Glaser et al.

    E-print Network

    Glaser, Rainer

    (12) United States Patent Glaser et al. US006229047B1 US 6,229,047 B1 May 8,2001 (10) Patent N0.: (45) Date of Patent: (54) DIPOLE ALIGNED NLO CHROMOPHORES (75) Inventors: Ranier E. Glaser; Grace S: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 USC 154(b) by 0 days

  6. (12) United States Patent Gentile et al.

    E-print Network

    Biewer, Theodore

    (12) United States Patent Gentile et al. US007711661B2 US 7,711,661 B2 May 4, 2010 (10) Patent N0.: (45) Date of Patent: (54) (75) (73) (*) (21) (22) (65) (63) (60) (51) (52) (58) SYSTEM AND METHOD, Princeton, N] (US) Notice: Subject to any disclaimer, the term ofthis patent is extended or adjusted under

  7. (12) United States Patent Vertes et al.

    E-print Network

    Vertes, Akos

    (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

  8. (12) United States Patent Vertes et al.

    E-print Network

    Vertes, Akos

    (12) United States Patent Vertes et al. (54) THREE-DIMENSIONAL MOLECULAR IMAGING BY INFRARED LASER) ( *) Notice: Subject to any disclaimer, the term ofthis patent is extended or adjusted under 35 U.S.c. 154(b/282,287,288; 4361173 See application file for complete search history. (56) References Cited U.S. PATENT DOCUMENTS 6

  9. (12) United States Patent Black et al.

    E-print Network

    Shamos, Michael I.

    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

  10. (12) United States Patent King et al.

    E-print Network

    Wolfe, Patrick J.

    (12) United States Patent King et al. USOO8914373B2 US 8,914,373 B2 Dec. 16, 2014 (10) Patent N0.: (45) Date of Patent: (54) (75) (73) (*) (21) (22) (65) (60) (51) (52) (58) PARTICIPANT GROUPING) Notice: Subject to any disclaimer, the term ofthis patent is extended or adjusted under 35 U.S.C. 154(b

  11. (12) United States Patent Grier et al.

    E-print Network

    Grier, David

    (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

  12. Al/Cl2 molten salt battery

    NASA Technical Reports Server (NTRS)

    Giner, J.

    1972-01-01

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

  13. 76 FR 62481 - Incapital LLC, et al.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-07

    ... From the Federal Register Online via the Government Printing Office SECURITIES AND EXCHANGE COMMISSION Incapital LLC, et al.; Notice of Application September 30, 2011. AGENCY: Securities and Exchange Commission (``Commission''). ACTION: Notice of application for an order under section 12(d)(1)(J) of...

  14. (12) United States Patent Hendricks et al.

    E-print Network

    Shamos, Michael I.

    (12) United States Patent Hendricks et al. (54) ELECTRONIC BOOK ELECTRONIC LINKS (75) Inventors-Arent Fox LLP (57) ABSTRACT An electronic book selection and delivery system distributes text to subscribers between specific electronic books and other electronic files. The links may be used or accessed by a menu

  15. (12) United States Patent Harvey et al.

    E-print Network

    Shamos, Michael I.

    CAMPAIGNS BY MATCHING MULTIPLE DATA SOURCES (75) Inventors: William Morris Harvey, Gardiner, NY (US); Gerald(12) United States Patent Harvey et al. (54) ANALYZING RETURN ON INVESTMENT OF ADVERTISING PUBLICATIONS Harvey, Better Television Audience Measurement Through the Research Integration of Set-Top Box

  16. Kinematics of Disease Progression in Bulbar ALS

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  17. (12) United States Patent Geohegan et al.

    E-print Network

    Geohegan, David B.

    (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

  18. Ternary Dy-Er-Al magnetic refrigerants

    DOEpatents

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

    1995-07-25

    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.

  19. Ternary Dy-Er-Al magnetic refrigerants

    DOEpatents

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

    1995-07-25

    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.

  20. U-ALS: A Ubiquitous Learning Environment

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  1. The Rail Gun Muad Al Khaldi

    E-print Network

    Masoudi, Husain M.

    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

  2. (12) United States Patent Grier et al.

    E-print Network

    Grier, David

    (12) United States Patent Grier et al. US008922857B2 US 8,922,857 B2 Dec. 30, 2014 (10) Patent N0.: (45) Date of Patent: (54) OPTICAL SOLENOID BEAMS (75) Inventors: David G. Grier, New York, NY (US, New York, NY (Us) ( * ) Notice: Subject to any disclaimer, the term ofthis patent is extended

  3. (12) United States Patent Grier et al.

    E-print Network

    Grier, David

    (12) United States Patent Grier et al. US008791985B2 US 8,791,985 B2 Jul. 29, 2014 (10) Patent N0.: (45) Date of Patent: (54) (75) (73) (21) (22) (86) (87) (65) (60) (51) (52) TRACKING to any disclaimer, the term ofthis patent is extended or adjusted under 35 U.S.C. 154(b) by 744 days. 12

  4. 76 FR 18783 - United States et al.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-05

    ... From the Federal Register Online via the Government Printing Office DEPARTMENT OF JUSTICE Antitrust Division United States et al. v. Dean Foods Company; Proposed Final Judgment, Stipulation and Competitive Impact Statement Notice is hereby given pursuant to the Antitrust Procedures and Penalties Act, 15 U.S.C. 16(b)-(h), that a proposed...

  5. Some TEM observations of Al2O3 scales formed on NiCrAl alloys

    NASA Technical Reports Server (NTRS)

    Smialek, J.; Gibala, R.

    1979-01-01

    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.

  6. Thermoelectric Powers of Cells With NaF-AlF3-Al2O3 Melts

    NASA Astrophysics Data System (ADS)

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

    2001-07-01

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

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

    SciTech Connect

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

    2009-02-01

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

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

    PubMed

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

    2006-12-28

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

  9. Oxalate Exudation by Taro in Response to Al1

    PubMed Central

    Ma, Zhong; Miyasaka, Susan C.

    1998-01-01

    Roots of taro (Colocasia esculenta [L.] Schott cvs Bun-long and Lehua maoli) exuded increasing concentrations of oxalate with increasing Al stress. This exudation was a specific response to excess Al and not to P deficiency. Addition of oxalate to Al-containing solutions ameliorated the toxic effect of Al. PMID:9808730

  10. Revisiting Deng et al.'s Multiparty Quantum Secret Sharing Protocol

    NASA Astrophysics Data System (ADS)

    Hwang, Tzonelih; Hwang, Cheng-Chieh; Yang, Chun-Wei; Li, Chuan-Ming

    2011-09-01

    The multiparty quantum secret sharing protocol [Deng et al. in Chin. Phys. Lett. 23: 1084-1087, 2006] is revisited in this study. It is found that the performance of Deng et al.'s protocol can be much improved by using the techniques of block-transmission and decoy single photons. As a result, the qubit efficiency is improved 2.4 times and only one classical communication, a public discussion, and two quantum communications between each agent and the secret holder are needed rather than n classical communications, n public discussions, and 3n/2 quantum communications required in the original scheme.

  11. Superconductivity of Al/Al2O3 interface formed by shock-wave pressure

    NASA Astrophysics Data System (ADS)

    Palnichenko, A. V.; Shakhrai, D. V.; Avdonin, V. V.; Vyaselev, O. M.; Khasanov, S. S.

    2015-05-01

    A mixture of Al and ? -Al2O3 has been subjected to a shock-wave pressure of ? 170 kbar, followed by vacuum-encapsulating and quenching of the product to liquid nitrogen. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc ? 37 K, characterized by glassy dynamics of the shielding currents below Tc . Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the interfacial granular layer formed between metallic Al and its oxide due to the shock-wave treatment.

  12. Ferromagnetic ordering in NpAl2: Magnetic susceptibility and 27Al nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Martel, L.; Griveau, J.-C.; Eloirdi, R.; Selfslag, C.; Colineau, E.; Caciuffo, R.

    2015-08-01

    We report on the magnetic properties of the neptunium based ferromagnetic compound NpAl2. We used magnetization measurements and 27Al NMR spectroscopy to access magnetic features related to the paramagnetic and ordered states (TC=56 K). While very precise DC SQUID magnetization measurements confirm ferromagnetic ordering, they show a relatively small hysteresis loop at 5 K reduced with a coercive field HCo~3000 Oe. The variable offset cumulative spectra (VOCS) acquired in the paramagnetic state show a high sensitivity of the 27Al nuclei spectral parameters (Knight shifts and line broadening) to the ferromagnetic ordering, even at room temperature.

  13. Superconductivity of Al/Al2O3 interface formed under shock-wave conditions

    NASA Astrophysics Data System (ADS)

    Shakhray, D. V.; Avdonin, V. V.; Palnichenko, A. V.; Vyaselev, O. M.

    2015-11-01

    A mixture of powdered Al and Al2O3 has been subjected to a shock-wave pressure of ? 170 kbar, followed by vacuum-encapsulating and quenching of the product to liquid nitrogen. The ac magnetic susceptibility measurements of the samples have revealed metastable superconductivity with Tc ? 37 K, characterized by glassy dynamics of the shielding currents below Tc. Comparison of the ac susceptibility and the dc magnetization measurements infers that the superconductivity arises within the interfacial granular layer formed between metallic Al and its oxide due to the shock-wave treatment.

  14. Solidification processing of intermetallic Nb-Al alloys

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  16. Core-excitonic lines at the Al 2p surface optical-absorption threshold of AlAs and AlP

    NASA Astrophysics Data System (ADS)

    Kelly, M. K.; Niles, D. W.; Perfetti, P.; Colavita, E.; Savoia, A.; Margaritondo, G.; Henzler, M.

    1985-10-01

    The optical-absorption spectra of AlAs and AlP exhibit unusual features-strong Al 2p core-excitonic lines. The data were obtained with synchrotron-radiation photoemission in the partial-yield mode. The analysis was based on the approach proposed by Johnson, Fock, Ley, and Cardona for AlSb and on Onodera and Toyozawa's exciton theory.

  17. Franklin et al., The Role of Consciousness in Memory 2005 Franklin et al. http//:www.brains-minds-media.org

    E-print Network

    Ramamurthy, Uma

    Franklin et al., The Role of Consciousness in Memory © 2005 Franklin et al. http//:www.brains-minds et al., The Role of Consciousness in Memory © 2005 Franklin et al. http//:www.brains-minds-media.org 1 The Role of Consciousness in Memory Stan Franklin1* , Bernard J. Baars2 , Uma Ramamurthy1

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

    E-print Network

    Widom, Michael

    in References 11, 18, 21, and 22. The Al2RE (cF24) is a Laves phase (C15, prototype Cu2Mg); in order to be compatible with the Laves phase description in other systems, Cacciamani et al.[18,20] modeled The present study reinvestigates the Al-Ce and Al-Nd phase diagrams and reoptimizes their thermody- namics

  19. LISTA PROVISIONAL DE ADMITIDOS AL CURSO DE ADAPTACIN AL GRADO DE INGENIERA CIVIL. CURSO 2015-16

    E-print Network

    Escolano, Francisco

    LISTA PROVISIONAL DE ADMITIDOS AL CURSO DE ADAPTACIÓN AL GRADO DE INGENIERÍA CIVIL. CURSO 2015 FRANCISCO JAVIER GARCÍA ESQUIVA TSU JOSE LUIS CORTES LOPEZ CC LISTA PROVISIONAL DE EXCLUIDOS AL CURSO DE ADAPTACIÓN AL GRADO DE INGENIERÍA CIVIL. CURSO 2015-16 NOMBRE APELLIDOS MOTIVO EXCLUSION PEDRO DÍAZ PUCHE

  20. LISTA DEFINITIVA DE ADMITIDOS AL CURSO DE ADAPTACIN AL GRADO DE INGENIERA CIVIL. CURSO 2015-16

    E-print Network

    Escolano, Francisco

    LISTA DEFINITIVA DE ADMITIDOS AL CURSO DE ADAPTACIÓN AL GRADO DE INGENIERÍA CIVIL. CURSO 2015 BALESTA CC MANUEL GOMIS ROMERO CC LISTA DEFINITIVA DE EXCLUIDOS AL CURSO DE ADAPTACIÓN AL GRADO DE INGENIERÍA CIVIL. CURSO 2015-16 NOMBRE APELLIDOS MOTIVO EXCLUSION CINTIA MARTINEZ SANCHEZ NO TITULADO PEDRO

  1. Elliott et al. Reply: Zhang et al. [1] have carried out classical molecular dynamics (MD) simulations using a

    E-print Network

    Elliott, James

    Elliott et al. Reply: Zhang et al. [1] have carried out classical molecular dynamics (MD of collapse pressure as a function of the tube diameter. Nevertheless, Zhang et al. demonstrate [1 in the enthalpy per atom reported by Zhang et al. (see Ref. [1], Table I) for the parallel and herringbone

  2. Non-statistical fluctuations for deep inelastic processes in 27Al + 27Al

    E-print Network

    I. Berceanu; M. Duma; D. Moisa; M. Petrovici; A. Pop; V. Simion; A. Del Zoppo; G. d'Erasmo; G. Imme; G. Lanzano; A. Pagano; A. Pantaleo; G. Raciti

    2005-01-06

    The excitation functions for different fragments produced in the 27Al + 27Al dissipative collisions have been measured in steps of 250 keV in the energy range 122 - 132 MeV. Deep inelastic processes have been selected by integrating events over a total kinetic energy loss window of 12 MeV between 20 and 32 MeV. Large fluctuations have been observed in all the studied excitation functions. Non-satistical origin of these fluctuations is confirmed by large channel cross correlations coefficients. Energy autocorrelation function of cross section excitation function presents damped oscillation structure as predicted for the case when a di-nuclear system with a lifetime similar with its revolution period is formed. The periodicity of the energy autocorrelation function is used to obtain information on the deformation of the 27Al + 27 Al di-nucleus.

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

    E-print Network

    Elkatsha, Markus Fawzy Fahmy

    2000-01-01

    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 ...

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

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    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.

  5. Fabrication and properties of functionally graded NiAl/Al2O3 composites

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

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

    SciTech Connect

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

    2014-07-28

    The lateral oxidation of thick AlGaAs layers (>500?nm) is studied. An uncommon shape of the oxide tip is evidenced and attributed to the embedded stress distribution, inherent to the oxidation reaction. Experimental and numerical studies of the internal strain in oxidized Al{sub x}Ga{sub 1?x}As/GaAs structures were carried out by dark-field electron holography and finite element methods. A mapping of the strain distribution around the AlGaAs/oxide interface demonstrates the main role of internal stress on the shaping of the oxide front. These results demonstrate the high relevance of strain in oxide-confined III-V devices, in particular, with over-500-nm thick AlOx confinement layers.

  7. Fusion cross sections for the 6,7Li+27Al, 9Be+27Al systems

    SciTech Connect

    Barbara, E. de; Marti, G. V.; Arazi, A.; Capurro, O. A.; Fernandez Niello, J. O.; Figueira, J. M.; Pacheco, A. J.; Ramirez, M.; Rodriguez, M. D.; Testoni, J. E.; Verruno, M.; Padron, I.; Gomes, P. R. S.

    2007-02-12

    We present the results of total fusion cross sections measurements for the 6,7Li + 27Al, 9Be + 27Al, systems at energies above and below the Coulomb barrier (0.8Vb {<=} E {<=} 2.0Vb). The experimental evidence at the measured energy regime show that the total fusion cross sections of 6Li and 9Be with a light mass target are not affected by the break-up process. The elastic break up cross sections for the 6Li + 27Al system were also measured and the results are being presented in this issue. The data for the 7Li + 27Al system are still being analyzed and therefore these results should be considered preliminary.

  8. Al-26 imaging details from COMPTEL

    NASA Astrophysics Data System (ADS)

    Diehl, R.; Knodlseder, J.; Bennett, K.; Bloemen, H.; Dupraz, C.; Hermsen, W.; Lichti, G. G.; Morris, D.; Oberlack, U.; Ryan, J.

    1995-05-01

    The Compton Telescope (COMPTEL) map of 1.809 MeV emission from Galactic Al-26 is now based on 2 1/2 years of data. Different imaging analysis approaches are discussed: Likelihood maps from point source scans are utilized for searches of emission regions; astrophysical source models are fitted to the measurement with the maximum likelihood method; deconvolved images are produced with the maximum entropy algorithm. Simulations and statistical analysis with the bootstrap method demonstrate that the intensity irregularity and asymmetry along the Galactic plane is significant, although weaker individual features are insignificant by themselves. The comparison of classical Al-26 source tracer distributions shows that none of these models represents the COMPTEL data well. The measured 1.809 MeV feature from the Vela region, positionally consistent with the Vela supernova remnant, shows an indication for extended emission.

  9. Observable Proxies For 26 Al Enhancement

    SciTech Connect

    Fryer, Christopher L; Young, Patrick A; Ellinger, Carola I; Arnett, William D

    2008-01-01

    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.

  10. Development of SiAlON materials

    NASA Technical Reports Server (NTRS)

    Layden, G. K.

    1979-01-01

    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.

  11. Status of the AlCap experiment

    E-print Network

    Litchfield, R Phillip

    2015-01-01

    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.

  12. The mechanical properties of FeAl

    SciTech Connect

    Baker, I.; George, E.P.

    1999-07-01

    In the last few years, considerable progress has been made in obtaining reproducible mechanical properties data for binary FeAl alloys. Two sets of observations are the foundation of this progress. The first is that the large equilibrium vacancy concentrations that exist in FeAl at high temperature are easily retained during cooling, and that these strongly affect the low-temperature mechanical properties. The second is that room-temperature ductility is adversely affected by water vapor. The purpose of this paper is to highlight their understanding of key phenomena and to show how an understanding of the factors which control the yield strength and fracture behavior has followed from the discovery of the above two effects. 94 refs., 8 figs.

  13. Berkeley Lab's ALS generates Femtosecond Synchrotron Radiation

    SciTech Connect

    Robinson, Arthur L.

    2000-05-23

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

  14. Status of the AlCap experiment

    E-print Network

    R. Phillip Litchfield

    2015-01-20

    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.

  15. Psychosocial adjustment to ALS: a longitudinal study

    PubMed Central

    Matuz, Tamara; Birbaumer, Niels; Hautzinger, Martin; Kübler, Andrea

    2015-01-01

    For the current study the Lazarian stress-coping theory and the appendant model of psychosocial adjustment to chronic illness and disabilities (Pakenham, 1999) has shaped the foundation for identifying determinants of adjustment to ALS. We aimed to investigate the evolution of psychosocial adjustment to ALS and to determine its long-term predictors. A longitudinal study design with four measurement time points was therefore, used to assess patients' quality of life, depression, and stress-coping model related aspects, such as illness characteristics, social support, cognitive appraisals, and coping strategies during a period of 2 years. Regression analyses revealed that 55% of the variance of severity of depressive symptoms and 47% of the variance in quality of life at T2 was accounted for by all the T1 predictor variables taken together. On the level of individual contributions, protective buffering, and appraisal of own coping potential accounted for a significant percentage in the variance in severity of depressive symptoms, whereas problem management coping strategies explained variance in quality of life scores. Illness characteristics at T2 did not explain any variance of both adjustment outcomes. Overall, the pattern of the longitudinal results indicated stable depressive symptoms and quality of life indices reflecting a successful adjustment to the disease across four measurement time points during a period of about two years. Empirical evidence is provided for the predictive value of social support, cognitive appraisals, and coping strategies, but not illness parameters such as severity and duration for adaptation to ALS. The current study contributes to a better conceptualization of adjustment, allowing us to provide evidence-based support beyond medical and physical intervention for people with ALS. PMID:26441696

  16. (12) United States Patent Gentile et al.

    E-print Network

    Biewer, Theodore

    (12) United States Patent Gentile et al. US006994831B1 (10) Patent N0.: (45) Date of Patent: US 6 of this patent is extended or adjusted under 35 U.S.C. 154(b) by 412 days. Appl. No.: 10/279,121 Filed: Oct. 23 history. References Cited U.S. PATENT DOCUMENTS 6,212,792 B1 * 4/2001 Bier

  17. (12) United States Patent Glazer et al.

    E-print Network

    Shamos, Michael I.

    , Glendale, AZ (US) 85310; David Armes, 4035 W. Banff La., Phoenix, AZ (US) 85033; Fred Alan Bishop, 2811 W. Dynamite Blvd., Phoenix, AZ (US) 85085; Michael Barrett, 9182 E. Carribean La., Scottsdale, AZ (US) 85260"'TU-;;OS~ER"'IDIP""A"'SS;;;WO"'R"'D"1--j207 NO #12;US 7,631,191 B2 Page 2 u.s. PATENT DOCUMENTS 6,735,694 Bl 5/2004 Berstis et al. 6

  18. (12) United States Patent Grier et al.

    E-print Network

    Grier, David

    (12) United States Patent Grier et al. US008921763B2 US 8,921,763 B2 Dec. 30, 2014 (10) Patent N0.: (45) Date of Patent: (54) (75) (73) (*) (21) (22) (65) (60) (51) (52) (58) EXTENDED AND KNOTTED disclaimer, the term ofthis patent is extended or adjusted under 35 U.S.C. 154(b) by 124 days. App1.No.: 13

  19. Thin film interactions of Al and Al(Cu) on TiW

    NASA Astrophysics Data System (ADS)

    Palmstrøm, C. J.; Mayer, J. W.; Cunningham, B.; Campbell, D. R.; Totta, P. A.

    1985-11-01

    Thin-film reactions of Al/Ti22W78 (˜10 wt. % Ti) with and without ˜2 at. % Cu in the Al were investigated by transmission electron microscopy for vacuum annealing in the temperature range 300-600 °C. The reactions are nonuniform and the presence of Cu has little effect on the reaction kinetics. Reactions are grain boundary dominated and start at 400 °C with the formation of WAl12.

  20. Diet and dietetics in al-Andalus.

    PubMed

    Salas-Salvadó, Jordi; Huetos-Solano, Maria D; García-Lorda, Pilar; Bulló, Mònica

    2006-08-01

    Al-Andalus society (711-1492) based its idea of health on the wisdom of Classical Greece, the Hippocratic-Galenic theories, as well as the Persian and Hindu cultures. The twelfth century in al-Andalus is considered to be the most prolific period for works of a scientific and technical nature. At the time, the main treatises on dietetics were written and this science reached its widest expression with such leading figures as Ibn W?f?d, Avenzoar, Averroes and Maimonides, whose works revealed the first scientific knowledge on the nutritional processes of the human body. Diet was regarded as being essential for health and the prevention of disease. Dietary guidelines were written for different age groups, different body types and different seasons of the year. The amount of food to be ingested, the number of meals recommended and the order in which the food should be consumed were all issues that were discussed. A variety of foods were thought to have medicinal properties, some of which are known today. The diet in al-Andalus was varied and very probably made a substantial contribution to the origin of the present-day Mediterranean diet, rich in olive oil, wholemeal cereals, fruit and vegetables, fish, lamb, poultry, nuts and spices. We also find that many of the terms in current use in diet and agriculture are a living testimony to the Arabic influence, as are many of the dishes of our varied Mediterranean gastronomy. PMID:16923240

  1. Room Temperature Radiolytic Synthesized Cu@CuAlO2-Al2O3 Nanoparticles

    PubMed Central

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

    2012-01-01

    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

  2. Heterogeneous reactivity of carbonyl sulfide on ?-Al 2O 3 and ?-Al 2O 3

    NASA Astrophysics Data System (ADS)

    Liu, Yongchun; He, Hong; Mu, Yujing

    The heterogeneous reactions of trace gases in the atmosphere on atmospheric particles could greatly affect the nitrogen, sulfur, ozone, and photochemical oxidant cycles. The uptake coefficient is an important kinetic parameter for atmospheric models to assess the role of heterogeneous reaction in the global cycles of trace gases. In this study, the heterogeneous uptake coefficients of carbonyl sulfide (OCS) on Al 2O 3 have been measured using a Knudsen cell reactor at 300 K. Hydrogen sulfide (H 2S) and carbon dioxide (CO 2) were found to be the gaseous products. The reaction mechanism of OCS on Al 2O 3 was confirmed based on previous work and this study. The true initial uptake coefficient and steady-state uptake coefficient of OCS on ?-Al 2O 3 were (3.8±0.8)×10 -7 and (6.5±2.49)×10 -8, and the corresponding uptake coefficients on ?-Al 2O 3 were (7.0±0.7)×10 -8 and (1.8±0.4)×10 -8, respectively. The annual flux of OCS due to heterogeneous reaction on ?-Al 2O 3 was calculated to be 0.11-0.63 Tg yr -1 based on the initial uptake coefficient and the steady-state uptake coefficient. When the fraction of Al 2O 3 in authentic atmospheric particles is taken into account, the annual flux of OCS due to heterogeneous reaction on atmospheric particles in the troposphere should be 0.02-0.10 Tg yr -1.

  3. TEM and HRTEM characterization of TiAl diffusion bonds using Ni/Al nanolayers.

    PubMed

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

    2015-02-01

    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

  4. Internal photoemission in Ag-Al2O3-Al junctions

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

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

    SciTech Connect

    Okumus, S. Cem Karslioglu, Ramazan Akbulut, Hatem

    2013-12-16

    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.

  6. Redistribution of Ti and Al in deuterium charged TiAl

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  7. The atomic details of the interfacial interaction between the bottom electrode of Al/AlOx/Al Josephson junctions and HF-treated Si substrates

    NASA Astrophysics Data System (ADS)

    Zeng, L. J.; Krantz, P.; Nik, S.; Delsing, P.; Olsson, E.

    2015-04-01

    The interface between the Al bottom contact layer and Si substrates in Al based Josephson junctions is believed to have a significant effect on the noise observed in Al based superconducting devices. We have studied the atomic structure of it by transmission electron microscopy. An amorphous layer with a thickness of ˜5 nm was found between the bottom Al electrode and HF-treated Si substrate. It results from intermixing between Al, Si, and O. We also studied the chemical bonding states among the different species using energy loss near edge structure. The observations are of importance for the understanding of the origin of decoherence mechanisms in qubits based on these junctions.

  8. 222-282 nm AlGaN and InAlGaN based deep-UV LEDs fabricated on high-quality AlN template

    NASA Astrophysics Data System (ADS)

    Hirayama, Hideki; Noguchi, Norimichi; Fujikawa, Sachie; Norimatsu, Jun; Kamata, Norihiko; Takano, Takayoshi; Tsubaki, Kenji

    2009-02-01

    We demonstrate 222-282 nm AlGaN and InAlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) fabricated on low threading dislocation density (TDD) AlN template. Low TDD AlN templates were realized by using ammonia (NH3) pulse-flow multilayer (ML) growth technique. The edge- and screw-type dislocation densities of AlN layer were reduced to 7.5×108 and 3.8×107, respectively. We obtained significant increase of an AlGaN quantum well (QW) emission (by more than 50 times) by fabricating them on a low TDD ML-AlN template. We fabricated AlGaN multi (M)QW DUV-LEDs with emission range of 222-273 nm on ML-AlN templates. Single-peaked electroluminescence (EL) was obtained for AlGaN DUV-LEDs. We obtained the maximum output power of 1.1, 2.4 and 3.3 mW for the AlGaN LEDs with wavelengths of 241, 253 and 273 nm, respectively, under RT CW operation. The maximum output power of 227 and 222 nm AlGaN-QW were 0.15mW and 0.014mW, respectively, under RT pulsed operation. The maximum external quantum efficiency (EQE) of the 227 and 250 nm AlGaN LEDs were 0.2% and 0.43 %, respectively. We also fabricated 280 nm-band quaternary InAlGaN-MQW DUV-LEDs with p-type InAlGaN layers on low TDD ML-AlN templates. We obtained significant increase of photoluminescence (PL) intensity by introducing Si-doped InAlGaN buffer and barrier layers and undoped InAlGaN interlayer. We then demonstrated high internal quantum efficiency (IQE) of 284 nm InAlGaN-QW emission, which was confirmed by the fact that the ratio of the integrated intensity of the RT-PL against the 77K-PL was 86%. The maximum output power and EQE of the 282 nm InAlGaN LED were 10.6 mW and 1.2%, respectively, under RT CW operation.

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

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2007-01-01

    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.

  10. Creep and Toughness of Cryomilled NiAl Containing Cr

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  11. Conformers of Al13, Al12M, and Al13M (M=Cu, Ag, and Au) clusters and their energetics

    NASA Astrophysics Data System (ADS)

    Zope, Rajendra R.; Baruah, Tunna

    2001-11-01

    The candidate structures for the ground-state geometry of the Al13, Al12M, and Al13M (M=Cu, Ag, and Au) clusters are obtained within the spin-polarized density-functional theory with a three-parameter hybrid functional to describe the exchange-correlation effects. Binding energy, vertical ionization potential, vertical electron affinity, and the energy gap between the highest-occupied molecular-orbital level and the lowest-unoccupied molecular-orbital level have been calculated to investigate the stability of these clusters. These results are compared with those of the alkali doped Al12 and Al13 clusters. The adatom energies (defined as the energy gained upon adding the atom to the host Al13 clusters) are found to be substantially larger for the coinage metal atom than those for alkali and Al atoms. The natural population analysis was carried out to get a qualitative picture of the bonding in these clusters.

  12. Short-period superlattices of AlN/Al{sub 0.08}Ga{sub 0.92}N grown on AlN substrates

    SciTech Connect

    Nikishin, S.A.; Borisov, B.A.; Chandolu, A.; Kuryatkov, V.V.; Temkin, H.; Holtz, M.; Mokhov, E.N.; Makarov, Yu.; Helava, H.

    2004-11-08

    High-quality short-period superlattices of AlN/Al{sub 0.08}Ga{sub 0.92}N have been grown by gas-source molecular-beam epitaxy with ammonia on Al face of AlN (0001) substrates. A significant reduction was achieved in the dislocation density, down to 3x10{sup 8} cm{sup -2}. Complete removal of residual Al{sub 2}O{sub 3} surface oxide is needed in order to obtain low dislocation density in homoepitaxy on AlN. We show that the presence of Al{sub 2}O{sub 3} islands with the surface coverage as low as 0.2% results in increased dislocation density.

  13. 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)

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

    2015-03-01

    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.

  14. Electronic properties of AlGaAs and AlGaAs/GaAs heterostructures

    SciTech Connect

    Leybovich, I.S.

    1986-01-01

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

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

    SciTech Connect

    Kim, Hyong June

    2011-12-01

    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.

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

    SciTech Connect

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

    2008-07-28

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2000-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  20. ALS 2883: Analysis of spectroscopic features

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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}.

  1. Properties of an AlGaN/AlN distributed-Bragg-reflector structure

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Li; Liu, Zhan-Hui; Huang, Xiao-Gu; Li, Qing-Fang; Zhang, Rong; Xie, Zi-Li; Xiu, Xiang-Qian

    2014-10-01

    An AlGaN/AlN distributed-Bragg-reflector (DBR) structure with a high Al content was grown by using plasma-assisted molecular beam epitaxy (PA-MBE). The properties of the sample were characterized by using the transmission electron microscopy, high-resolution X-ray diffraction, atomic force microscopy, and reflectivity spectrum measurements. The reciprocal space mapping analysis indicated that the strain in the AlGaN layers was partially relaxed. The morphology of the DBR exhibited a surface covered by grains (average size of about 130 nm), and the surface roughness was about 2 nm. The spectral measurements showed that the DBR structure presented a peak reflectivity of 68.8% at the center wavelength of 247 nm, which indicated that this DBR structure could work in the deep solar-blind UV region with acceptable reflectivity. However, the optical properties of the DBR structure were deteriorated by the fluctuation of the Al composition, non-uniformity of the layer thickness, the blurry, rough interface in the DBR structure, and so on.

  2. Deep SiO2 etching with Al and AlN masks for MEMS devices

    NASA Astrophysics Data System (ADS)

    Bliznetsov, Vladimir; Mao Lin, Hua; Zhang, Yue Jia; Johnson, David

    2015-08-01

    Silicon oxide-based materials such as quartz and silica are widely used in microelectromechanical systems (MEMS). One way to enhance the capability of their deep plasma etching is to increase selectivity by the use of hard masks. Although this approach was studied previously, information on the use of hard masks for the etching of silicon-oxide based materials on 200?mm substrates is scarce. We present the results of etching process development for amorphous silicon oxide using Al and AlN masks with a view of the application of the results for the etching of silica and quartz. Three gas chemistries (C4F8/O2, CF4 and SF6) and their mixtures were compared in an industrial reactive ion etch (RIE) chamber with two plasma sources. It was established that pure SF6 is the best etchant and AlN is a better mask than Al for providing higher selectivity and a sidewall angle close to vertical. A range of etching parameters for micromasking-free etching was established and etched structures of up to a 4?:?1 aspect ratio were created in 21??m-thick oxide using the process with an etch rate of 0.32-0.36??m?min-1 and a selectivity to AlN mask of (38-49) : 1.

  3. Simulations of nanoscale Ni/Al multilayer foils with intermediate Ni2Al3 growth

    NASA Astrophysics Data System (ADS)

    Gunduz, I. E.; Onel, S.; Doumanidis, C. C.; Rebholz, C.; Son, S. F.

    2015-06-01

    Nanoscale multilayers of binary metallic systems, such as nickel/aluminum, exhibit self-propagating exothermic reactions due to the high formation enthalpy of the intermetallic compounds. Most of the previous modeling approaches on the reactions of this system rely on the use of mass diffusion with a phenomenological derived diffusion coefficient representing single-phase (NiAl) growth, coupled with heat transport. We show that the reaction kinetics, temperatures, and thermal front width can be reproduced more satisfactorily with the sequential growth of Ni2Al3 followed by NiAl, utilizing independently obtained interdiffusivities. The computational domain was meshed with a dynamically generated bi-modal grid consisting of fine and coarse zones corresponding to rapid and slower reacting regions to improve computational efficiency. The PDEPE function in MATLAB was used as a basis for an alternating direction scheme. A modified parabolic growth law was employed to model intermetallic growth in the thickness direction. A multiphase enthalpy function was formulated to solve for temperatures after discrete phase growth and transformations at each time step. The results show that the Ni2Al3 formation yields a preheating zone to facilitate the slower growth of NiAl. At bilayer thicknesses lower than 12 nm, the intermixing layer induces oscillating thermal fronts, sharply reducing the average velocities.

  4. Orbit stability of the ALS storage ring

    SciTech Connect

    Keller, R.; Nishimura, H.; Biocca, A.

    1997-05-01

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

  5. Lympholyte (Obokata et al., Nature, 2014, retracted)

    E-print Network

    Fukai, Tomoki

    STAP : 2014827 1 #12;STAP STAP Cre-loxP 2 #12; HCl C57BL/6 Oct3/4GFP GOF 5 8 10 12 µl/500 µl of HBSS HCl10l35%HCl590lHBSS pH 4 #12;17 Oct3/4 GFP GOF DNA Oct3/4GFP (GOF) 5 #12;STAP Oct3/4GFP (GOF)GFP (Obokata et al., Nature, 2014, retracted) 6 #12;HCl 7 HClµl/500 µl

  6. ALS insertion device block measurement and inspection

    SciTech Connect

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

    1991-05-01

    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.

  7. Development of SiAlON materials

    NASA Technical Reports Server (NTRS)

    Layden, G. K.

    1977-01-01

    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.

  8. First-principles studies of Al-Ni intermetallic compounds

    SciTech Connect

    Shi Dongmin; Wen Bin; Melnik, Roderick; Yao Shan; Li Tingju

    2009-10-15

    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.

  9. Investigation of etching techniques for superconductive Nb/Al-Al2O3/Nb fabrication processes

    NASA Technical Reports Server (NTRS)

    Lichtenberger, A. W.; Lea, D. M.; Lloyd, F. L.

    1993-01-01

    Wet etching, CF4 and SF6 reactive ion etching (RIE), RIE/wet hybrid etching, Cl-based RIE, ion milling, and liftoff techniques have been investigated for use in superconductive Nb/Al-Al2O3/Nb fabrication processes. High-quality superconductor-insulator-superconductor (SIS) junctions have been fabricated using a variety of these etching methods; however, each technique offers distinct tradeoffs for a given process an wafer design. In particular, it was shown that SF6 provides an excellent RIE chemistry for low-voltage anisotropic etching of Nb with high selectivity to Al. The SF6 tool has greatly improved the trilevel resist junction insulation process. Excellent repeatability, selectivity with respect to quartz, and submicron resolution make Cl2 + BCl3 + CHCl3 RIE a very attractive process for trilayer patterning.

  10. Energy localization on the Al sublattice of Pt3Al with L12 order

    SciTech Connect

    Medvedev, Nikolay N; Starostenkov, Mikhail D; Manley, Michael E

    2013-01-01

    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.

  11. FORMING Al-Al2O3 NANOCOMPOSITE SURFACES USING FRICTION STIR PROCESSING

    SciTech Connect

    Qu, Jun; Xu, Hanbing; Feng, Zhili; An, Ke; Battiste, Rick; An, Linan; Heinrich, Helge

    2009-01-01

    This study presents a solid state surface engineering process to form a nanocomposite layer on aluminum surface. Friction stir processing (FSP) was used to stir and mix nano-sized Al2O3 particles into a commercially pure aluminum surface to form an Al-Al2O3 nanocomposite layer of up to several millimeters thick. Compared with a non-processed aluminum surface, a nanocomposite surface with 15 vol% nano-particles has demonstrated increased hardness (by 3X) and yield strength (by 10X), and reduced friction coefficient (by 55%) and wear rate (by 100X). Transmission electron microscopy (TEM) has revealed high matrix dislocation density in the nanocomposite surface that is believed to be largely responsible to such significant property improvements. Neutron diffraction measurements suggested tensile residual stress in the aluminum matrix. The stress was mainly induced by thermal-expansion-mismatch between aluminum and alumina.

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

    SciTech Connect

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

    1999-07-01

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

  13. Reaction diffusion in the NiCrAl and CoCrAl systems

    NASA Technical Reports Server (NTRS)

    Levine, S. R.

    1978-01-01

    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.

  14. Abrupt Schottky Junctions in Al/Ge Nanowire Heterostructures

    PubMed Central

    2015-01-01

    In this Letter we report on the exploration of axial metal/semiconductor (Al/Ge) nanowire heterostructures with abrupt interfaces. The formation process is enabled by a thermal induced exchange reaction between the vapor–liquid–solid grown Ge nanowire and Al contact pads due to the substantially different diffusion behavior of Ge in Al and vice versa. Temperature-dependent I–V measurements revealed the metallic properties of the crystalline Al nanowire segments with a maximum current carrying capacity of about 0.8 MA/cm2. Transmission electron microscopy (TEM) characterization has confirmed both the composition and crystalline nature of the pure Al nanowire segments. A very sharp interface between the ?111? oriented Ge nanowire and the reacted Al part was observed with a Schottky barrier height of 361 meV. To demonstrate the potential of this approach, a monolithic Al/Ge/Al heterostructure was used to fabricate a novel impact ionization device. PMID:26052733

  15. Effect of Al Content in Al/TiO2 Powder Mixture on Formation of Phases in ?-TiAl/Al2O3 Nano Composite Prepared by Mechanical Alloying

    NASA Astrophysics Data System (ADS)

    Heshmati-Manesh, S.; Alamolhoda, S.; Ataie, A.

    2009-06-01

    Mechanochemical synthesis of a nano composite comprising a nano structured ?-TiAl alloy matrix and nano crystalline Al2O3 particles, was studied in this research. The precursors consisted of TiO2 powder mixed together with various amounts of Al powder. The mixtures were subjected to intense mechanical activation in a high energy ball mill. Milled powders were cold pressed and heated to form the final nano composite phases and to sinter them together. Thermal behavior of milled powders was studied by DTA technique. DTA results of samples show that by increasing the Al content of samples, the intensity of aluminothermic reaction increases and the temperature of TiAl formation decreases. Also, the effect of Al content on structure of sintered samples was studied by XRD and SEM techniques. XRD results indicate that by increasing of the Al content, less Ti3Al phase is formed.

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

    SciTech Connect

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

    1998-11-01

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

  17. Hydrogenic donor in asymmetric AlGaAs/GaAs/AlGaAs quantum wells

    NASA Astrophysics Data System (ADS)

    Akbas, H.; Dane, C.; Erdogan, I.; Akankan, O.

    2014-06-01

    In this work we study the effects of barrier height ratio VL/VR on asymmetric AlGaAs/GaAs/AlGaAs quantum wells in absence of external influences. We use a variational method within the effective mass approximation to observe the effects of the barrier height ratio. It has been observed that the binding energy of the impurity, the expectation value of the electron-impurity distance along the z-direction, density of impurity states, and edge binding energy difference depend strongly on the barrier height ratio. Furthermore we present new curves that analyze the binding energy of asymmetric quantum wells as functions of barrier height ratio.

  18. InAlGaAs/AlGaAs Superlattices for Polarized Electron Photocathodes

    SciTech Connect

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

    2005-08-15

    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.

  19. Inferred Initial 26Al/27Al Ratios in Presolar Stardust Grains from Supernovae are Higher than Previously Estimated

    NASA Astrophysics Data System (ADS)

    Groopman, Evan; Zinner, Ernst; Amari, Sachiko; Gyngard, Frank; Hoppe, Peter; Jadhav, Manavi; Lin, Yangting; Xu, Yuchen; Marhas, Kuljeet; Nittler, Larry R.

    2015-08-01

    We performed an in-depth exploration of the Al-Mg system for presolar graphite, SiC, and Si3N4 grains found to contain large excesses of 26Mg, indicative of the initial presence of live 26Al. Ninety of the more than 450 presolar grains processed in this study contain well-correlated {? }26{Mg}{/}24{Mg} and 27Al/24Mg ratios, derived from Nano-scale Secondary Ion Mass Spectrometer depth profiles, whose isochron-like regression lines yield inferred initial {}26{Al}{/}27{Al} ratios that, on average, are ˜1.5-2 times larger than the ratios previously reported for the grains. The majority of presolar graphite and SiC grains are heavily affected by Al contamination, resulting in large negative {? }26{Mg}{/}24{Mg} intercepts of the isochron lines. Al contamination is potentially due to etching of the grains’ surfaces and subsequent capture of dissolved Al during the acid dissolution of their meteorite host rocks. From the isochron fits, the magnitude of Al contamination was quantified for each grain. The amount of Al contamination on each grain was found to be random and independent of grain size, following a uniform distribution with an upper bound at 59% contamination. The Al contamination causes conventional whole-grain estimates to underpredict the initial {}26{Al}{/}27{Al} ratios. The presolar grains with the highest {}26{Al}{/}27{Al} ratios are from Type II supernovae whose isochron-derived initial {}26{Al}{/}27{Al} ratios greatly exceed those predicted in the He/C and He/N zones of SN models.

  20. Effect of Al on the Wetting Behavior Between TiC x and Molten Ti-Al Alloys

    NASA Astrophysics Data System (ADS)

    Liu, Xuyang; Lv, Xuewei; Dong, Hongbiao; Li, Chunxin; Bai, Chenguang

    2015-10-01

    The wetting behavior and the interfacial reactions between TiC x substrate and molten Ti-Al alloys with different Al contents were studied using the Sessile Drop method at 1758 K (1485 °C) in argon atmosphere. It is found that the wettability and interface reaction products depend on Al content in the molten alloy. The initial contact angles between the molten Ti-Al alloy and TiC0.78 surface reduces from 110 to 80 deg when Al content in the alloy changes from 40 to 80 wt pct. The reduction in the initial contact angle is due to the decrease of surface tension of the molten Ti-Al alloys with increasing Al contents. The segregation of Al atoms to the surface occurred at all bulk concentrations of Ti-Al alloys. Al with lower surface tension tends to segregate on the surface of liquid Ti-Al alloy. In the spreading stage, the interfacial reaction led to the decrease in the contact angle. The adhesion in Ti-Al/TiC x system can be interpreted in terms of strong chemical interactions, which is greatly affected by the diffusion of C. The equilibrium contact angle was measured less than 10 deg. Finally, the reaction sequence at the Ti-Al melt and TiC x substrate interface is proposed.

  1. Simulation Study of Al-1Mn/Al-10Si Circular Clad Ingots Prepared by Direct Chill Casting

    NASA Astrophysics Data System (ADS)

    Wu, Li; Kang, Huijun; Chen, Zongning; Fu, Ying; Wang, Tongmin

    2015-10-01

    A modified direct chill casting process based on Novelis FusionTM Technology co-casting process was used recently to prepare Al-1Mn/Al-10Si circular clad ingots. In the current study, a comprehensive simulation model was developed to investigate the direct chill casting process for preparing the Al-1Mn/Al-10Si circular clad ingots, and a parametric study and experimental research of the direct chill casting process was conducted to explore potential success and failure casting conditions. The simulation results revealed the bonding mechanism of the Al-1Mn/Al-10Si interface in the direct chill casting process and identified the effect of certain parameters on casting performance. The results indicated that the effect of casting speed and Al-1Mn casting temperature on the variations of the minimum solid fraction of Al-1Mn at the interface is stronger than that of cooling water flow rate in inner mold, while Al-10Si casting temperature is the weakest of the four casting parameters. The corresponding experimental results verified that Al-1Mn/Al-10Si circular clad ingot with acceptable metallurgical bonding can be successfully prepared by direct chill casting process under the proper casting parameters. The thickness of diffusion zone is about 40 ?m, and the fractured position in tensile test was located in the Al-1Mn alloy side which indicated the strength of the interfacial region is higher than that of Al-1Mn alloy.

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    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.

  3. Comparison on the interaction of Al3+/nano-Al13 with calf thymus DNA /salmon sperm DNA

    NASA Astrophysics Data System (ADS)

    Ma, Fei; Ma, Yue; Du, Changwen; Yang, Xiaodi; Shen, Renfang

    2015-11-01

    The conformation change, binding mode and binding site between Al3+/nano-Al13 and calf thymus DNA/salmon sperm DNA were investigated by UV-vis absorption, FTIR spectra, Raman spectroscopy and CD spectra, as well as melting curves measurement. The UV-vis spectra and circular dichroism spectra results suggested that the phosphate group structure was changed when Al3+ interacted with DNA, while the double-helix was distorted when nano-Al13 interacted with DNA. The FTIR and Raman spectroscopy revealed that the binding sites were Al3+ … PO2, Al3+ … N7/guanine PO2 … Al13 … N7-C8/guanine with calf thymus DNA, and Al3+ … N3-O2/cytosine, Al3+ … N7-C8/guanine, PO2 … Al13 … N7-C8/guanine, PO2 … Al13 … N1/adenine with salmon sperm DNA, respectively. The electrostatic binding was existed between Al3+ and DNA, and the electrostatic binding and complexing were found between nano-Al13 and DNA.

  4. Through Thickness Microstructural and Texture Inhomogeneity Within Al Layers in ARB-Produced Al-Al(Sc) Layered Composite Sheets

    NASA Astrophysics Data System (ADS)

    Najafzadeh, Niloofar; Quadir, M. Z.; Munroe, Paul

    2015-10-01

    Alternatively layered composite sheets of commercially pure (99.8 pct purity) aluminum and an Al-0.3wtpctSc alloy (either in the supersaturated solid solution or age-hardened conditions) were generated through accumulative roll bonding for up to 5 cycles. The transverse sections of the sheets were examined to investigate the microstructure and texture inhomogeneities developed during the rolling process. Electron backscatter diffraction and transmission electron microscopy was used for this investigation. It was found that an inhomogeneous microstructure and texture was developed through the aluminum layers of the sheet thickness. The nature of inhomogeneities changes as the ARB bonding progresses to higher cycles. Microstructural inhomogeneities remain prominent in the first ARB cycle and diminish during the subsequent cycles. Texture inhomogeneities appear in different forms as rolling progresses. High frictional shear forces in the surface and in-plane shear forces across bonding interfaces derive these inhomogeneities.

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

  6. SEAL --A Framework for Developing SEmantic Web PortALs

    E-print Network

    Staab, Steffen

    SEAL -- A Framework for Developing SEmantic Web PortALs ½ ¿ Alexander Maedche, ½ ¾ Steffen Staab portals, viz. SEAL (SEmantic portAL), that exploits semantics for providing and accessing information the foundation of our SEAL (SEmantic portAL) ap- proach. The origins of SEAL lie in Ontobroker [5], which

  7. SEAL --A Framework for Developing SEmantic PortALs

    E-print Network

    Staab, Steffen

    SEAL -- A Framework for Developing SEmantic PortALs 1HQDG 6WRMDQRYLF Institute AIFB University for developing semantic portals, YL] SEAL (SE- mantic portAL), that exploits semantics for providing-based portal applications, namely SEAL (SEmantic PortAL) and its semantic mechanism for acquiring, struc

  8. MCrAlY bond coat with enhanced Yttrium layer

    DOEpatents

    Jablonski, Paul D; Hawk, Jeffrey A

    2015-04-21

    One or more embodiments relates to an MCrAlY bond coat comprising an MCrAlY layer in contact with a Y--Al.sub.2O.sub.3 layer. The MCrAlY layer is comprised of a .gamma.-M solid solution, a .beta.-MAl intermetallic phase, and Y-type intermetallics. The Y--Al.sub.2O.sub.3 layer is comprised of Yttrium atoms coordinated with oxygen atoms comprising the Al.sub.2O.sub.3 lattice. Both the MCrAlY layer and the Y--Al.sub.2O.sub.3 layer have a substantial absence of Y--Al oxides, providing advantage in the maintainability of the Yttrium reservoir within the MCrAlY bulk. The MCrAlY bond coat may be fabricated through application of a Y.sub.2O.sub.3 paste to an MCrAlY material, followed by heating in a non-oxidizing environment.

  9. Comparative Genomic Discovery of miRNAs Grad et al.

    E-print Network

    Church, George M.

    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 sites in the 3 untranslated region (UTR) of their target mRNAs and repressing their translation (Lee et

  10. 77 FR 67689 - Fidelity Aberdeen Street Trust, et al.;

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-13

    ... COMMISSION Fidelity Aberdeen Street Trust, et al.; Notice of Application November 6, 2012. AGENCY: Securities... certain joint arrangements (``Prior Order'').\\1\\ \\1\\ Colchester Street Trust, et al., Investment Company..., Colchester Street Trust, et al., Investment Company Act Release Nos. 23787 (Apr. 15, 1999) (notice) and...

  11. Diagnostic timelines and delays in diagnosing amyotrophic lateral sclerosis (ALS).

    PubMed

    Paganoni, Sabrina; Macklin, Eric A; Lee, Alexandra; Murphy, Alyssa; Chang, Judith; Zipf, Amanda; Cudkowicz, Merit; Atassi, Nazem

    2014-09-01

    The objective of this study was to characterize the diagnostic timelines and their predictors in people with amyotrophic lateral sclerosis (ALS). Patients were identified through ALS billing codes. Time from presenting symptom to first doctor visit, first doctor visit to suspected ALS diagnosis, suspected to confirmed ALS diagnosis, and presenting symptom to confirmed ALS diagnosis (total diagnostic time) were collected. Regression models were used to analyze the predictors of diagnostic delay. Three hundred and four ALS patients were included in the analysis. Median total diagnostic time was 11.5 months. Diagnostic timelines were longer in patients with age > 60 years (p < 0.001), sporadic ALS (p = 0.043), and limb onset (p = 0.010). The presence of fasciculations, slurred speech, and lower extremity weakness when symptoms were first noted were independent predictors of shorter time to ALS diagnosis (p = 0.04, p = 0.02, and p = 0.04, respectively). About half of the patients (52%) received an alternative diagnosis and each patient saw an average of three different physicians before ALS diagnosis was confirmed. In conclusion, diagnostic timelines in ALS are long, and patients see many physicians and receive multiple alternative diagnoses before the diagnosis of ALS is confirmed. Older age, sporadic disease, and limb onset can delay ALS diagnosis. PMID:24981792

  12. Screw dislocation-induced growth spirals as emissive exciton localization centers in Al-rich AlGaN/AlN quantum wells

    NASA Astrophysics Data System (ADS)

    Funato, Mitsuru; Banal, Ryan G.; Kawakami, Yoichi

    2015-11-01

    Screw dislocations in Al-rich AlGaN/AlN quantum wells cause growth spirals with an enhanced Ga incorporation, which create potential minima. Although screw dislocations and their surrounding potential minima suggest non-radiative recombination processes within growth spirals, in reality, screw dislocations are not major non-radiative sinks for carriers. Consequently, carriers localized within growth spirals recombine radiatively without being captured by non-radiative recombination centers, resulting in intense emissions from growth spirals.

  13. Electronic structure and bonding properties of layered machinable Ti2AlC and Ti2AlN ceramics

    NASA Astrophysics Data System (ADS)

    Zhou, Yanchun; Sun, Zhimei

    2000-05-01

    The electronic structure and chemical bonding of the layered ternary compounds Ti2AlC and Ti2AlN have been calculated by the ab initio pseudopotential total-energy method. The results show that Ti2AlC and Ti2AlN exhibit metallic electrical conductivity with an anisotropic character and Ti2AlC should be more conductive than Ti2AlN. The chemical bonding in Ti2AlC and Ti2AlN is also anisotropic and is metallic-covalent-ionic in nature. On the basis of total-energy estimation we conclude that the replacement of C by N will result in a stabilization of the hexagonal structure and decrease in metallic properties.

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

    SciTech Connect

    Music, Denis; Nahif, Farwah; Friederichsen, Niklas; Schneider, Jochen M.; Sarakinos, Kostas

    2011-03-14

    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.

  15. 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

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

    2009-07-01

    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

  16. Co-existence of a few and sub micron inhomogeneities in Al-rich AlGaN/AlN quantum wells

    NASA Astrophysics Data System (ADS)

    Iwata, Yoshiya; Oto, Takao; Gachet, David; Banal, Ryan G.; Funato, Mitsuru; Kawakami, Yoichi

    2015-03-01

    Inhomogeneity in Al-rich AlGaN/AlN quantum wells is directly observed using our custom-built confocal microscopy photoluminescence (?-PL) apparatus with a reflective system. The ?-PL system can reach the AlN bandgap in the deep ultra-violet spectral range with a spatial resolution of 1.8 ?m. In addition, cathodoluminescence (CL) measurements with a higher spatial resolution of about 100 nm are performed. A comparison of the ?-PL and CL measurements reveals that inhomogeneities, which have different spatial distributions of a few- and sub-micron scales that are superimposed, play key roles in determining the optical properties.

  17. Cyclic Oxidation of FeCrAlY/Al2O3 Composites

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.; Draper, Susan L.; Barrett, Charles A.

    1999-01-01

    Three-ply FeCrAlY/Al2O3 composites and FeCrAlY matrix-only samples were cyclically oxidized at 1000 C and 1100 C for up to 1000 1-hr cycles. Fiber ends were exposed at the ends of the composite samples. Following cyclic oxidation, cracks running parallel to and perpendicular to the fibers were observed on the large surface of the composite. In addition, there was evidence of increased scale damage and spallation around the exposed fiber ends, particularly around the middle ply fibers. This damage was more pronounced at the higher temperature. The exposed fiber ends showed cracking between fibers in the outer plies, occasionally with Fe and Cr-rich oxides growing out of the cracks. Large gaps developed at the fiber/matrix interface around many of the fibers, especially those in the outer plies. Oxygen penetrated many of these gaps resulting in significant oxide formation at the fiber/matrix interface far within the composite sample. Around several fibers, the matrix was also internally oxidized showing Al2O3 precipitates in a radial band around the fibers. The results show that these composites have poor cyclic oxidation resistance due to the CTE mismatch and inadequate fiber/matrix bond strength at temperatures of 1000 C and above.

  18. 1: Introduction Bedau et al [Bedau et al, 1997, Smith and Bedau, 1999

    E-print Network

    Nehaniv, Chrystopher

    the accumulation of adaptive changes in the genotypes of several Artificial Life (AL) "organisms into the quantification of adaptive behaviour as shown in various models of artificial evolution. They compare in the fossil record with a similarly derived neutral fossil record. In the artificial models the results show

  19. Magnetization anomaly of Nb3Al strands and instability of Nb3Al Rutherford cables

    SciTech Connect

    Yamada, Ryuji; Kikuchi, Akihiro; Wake, Masayoshi; /KEK, Tsukuba

    2006-08-01

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

  20. Aspects Analytiques Dans la Mathematique De Sharaf Al-D\\^in Al-T\\^US\\^I

    E-print Network

    Fares, Nicolas

    2009-01-01

    The analytical aspects of the "Trait\\'e des \\'equations" of Sharaf al-D\\^in al-T\\^us\\^i (2nd half of the XIIth century) have been underlined by R. Rashed (1974, 1986). In the present paper, we consider again some of those aspects, when studying the "second part" of the "Trait\\'e". We find out that al-T\\^us\\^i introduces certain notions, develops reasonings and uses calculating procedures that may allow his work to be an important reference in the history of the mathematical analysis. As such, one is led to examine the foundations of a J.P. Hogendijk conjecture (1989), which situates the advanced mathematics of this "2nd Part" in the only domain of Euclidian geometry. Simultaneously, we shall try to shed some light on a passage of the "Trait\\'e", made unclear by al-T\\^us\\^i style and expression. Our study is essentially based on the texts to confirm the originality and the importance of these XIIth century mathematics. I would like to express my thanks to Prof. C. Houzel (Univ. Paris VII) and B. El-Mabsout (Un...

  1. High Temperature Mechanical Characterization and Analysis of Al2O3 /Al2O3 Composition

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John Z.; Jaskowiak, Martha H.

    1999-01-01

    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.

  2. Guided lamb wave electroacoustic devices on micromachined AlN/Al plates.

    PubMed

    Di Pietrantonio, Fabio; Benetti, Massimiliano; Cannatà, Domenico; Beccherelli, Romeo; Verona, Enrico

    2010-05-01

    An electroacoustic micro-device based on the propagation of guided acoustic Lamb waves in AlN/Al plate is described. The AlN thin film is deposited by sputtering technique, optimized to achieve a high degree of orientation (rocking curve full-width at half-maximum /sp lap/ 3.5 degrees ) of the c-axis perpendicular to the plate surface. The AlN plate is micromachined using anisotropic reactive ion etching (RIE), followed by isotropic RIE to remove the silicon underlayer. Simulation results for the dispersion phase velocity curves and the electromechanical coupling coefficient (K(2)) are obtained by the matrix method and by the finite element method and compared with experimental data. A delay line is implemented on the structure and tested for the propagation of the first symmetrical Lamb mode (s(0)) at the frequency of 1.22 GHz. Measurements have shown that the structure is suitable for implementation of arrays of electroacoustic devices on a single chip for application to both sensing devices and signal processing systems. PMID:20442029

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  4. Constitutive Model Constants for Al7075-T651 and Al7075-T6

    NASA Astrophysics Data System (ADS)

    Brar, Nachhatter; Joshi, Vasant; Harris, Bryan

    2009-06-01

    Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these material. J-C strength model constants (A, B, n, C, and m) for the two alloys are determined from tension stress-strain data at room and high temperature to 250^oC. J-C strength model constants for Al7075-T651 are: A=527 MPa, B=676 MPa, n=0.71, C=0.017, and m=1.61 and for Al7075-T6: A = 546 MPa, B = 674 MPa, n = 0.72, C = 0.059, and m =1.56. J-C fracture model constants are determined form quasi-static and high strain rate/high temperature tests on notched and smooth tension specimens. J-C fracture model constants for the two alloys are: Al7075-T651; D1 = 0.110, D2 = 0.573, D3= -3.4446, D4 = 0.016, and D 5= 1.099 and Al7075-T6; D1= 0.451 D2= -0.952 D3= -.068, D4 =0.036, and D5 = 0.697.

  5. NiAl powder alloys: II. Compacting of NiAl powders produced by various methods

    NASA Astrophysics Data System (ADS)

    Skachkov, O. A.; Povarova, K. B.; Drozdov, A. A.; Morozov, A. E.

    2012-05-01

    The technological properties of granulated NiAl powders produced by gas spraying of melts and NiAl powders produced by calcium hydride reduction (CHR) of mixtures of nickel and aluminum oxides are compared. The possibilities of production of compact workpieces from these powders using hydrostatic pressing, hot pressing, hot isostatic pressing, and hot extrusion are estimated. To improve compressibility, preliminary milling and/or mechanical activation of the powders are proposed. The strength properties of NiAl rods with a diameter of 20 mm extruded from a temperature of 1100°C and made from the granulated powders are slightly higher than those made from the CHR powders. At temperatures higher than 800°C the properties becomes similar. Transition point t d.b from the ductile to brittle state of samples made from powders sprayed in nitrogen and argon is 100-150°C higher than those made from the CHR powders. The difference in the mechanical properties is caused by the structural and chemical microheterogeneity of granules (microingots), which is inherited in the rods after hot deformation and annealing at 1200-1400°C and is (0.67-0.88) T m NiAl ( T m is the melting point, K).

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

    NASA Astrophysics Data System (ADS)

    Kumar, Rajender; Chand, Subhash

    2015-01-01

    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.

  7. Single-crystal AlN nanonecklaces

    NASA Astrophysics Data System (ADS)

    Wang, Huatao; Xie, Zhipeng; Wang, Yiguang; Yang, Weiyou; Zeng, Qingfeng; Xing, Feng; An, Linan

    2009-01-01

    Distinct single-crystal aluminum nitride nanonecklaces with uniform \\{10\\bar {1}1\\} faceted beads are synthesized via catalyst-assisted nitriding of Al. The detailed morphology and structure of the nanonecklaces have been characterized. The growth process has been investigated by comparing the products obtained at different synthesis times. The results reveal that the formation of the nanonecklaces is via a process consisting of facet formation and bead unification. The formation of the \\{10\\bar {1}1\\} facets is due to the presence of a liquid phase that lowers the surface tension of otherwise high-energy \\{10\\bar {1}1\\} planes. The bead unification is driven by minimizing the energy contributed by surface energy and electrostatic energy. The unique morphology of the nanonecklaces could be useful for studying fundamental physical phenomena and fabricating nanodevices.

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

    E-print Network

    International Association for Cryptologic Research (IACR)

    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

  9. Creep in Directionally Solidified NiAl-Mo Eutectics

    SciTech Connect

    Dudova, Marie; Kucharova, Kveta; Bartak, Tomas; Bei, Hongbin; George, Easo P; Somsen, Ch.; Dlouhy, A.

    2011-01-01

    A directionally solidified NiAl-Mo eutectic and an NiAl intermetallic, having respective nominal compositions Ni-45.5Al-9Mo and Ni-45.2Al (at.%), were loaded in compression at 1073 and 1173 K. Formidable strengthening by regularly distributed Mo fibres (average diameter 600 nm, volume fraction 14%) was observed. The fibres can support compression stresses transferred from the plastically deforming matrix up to a critical stress of the order of 2.5 GPa, at which point they yield. Microstructural evidence is provided for the dislocation-mediated stress transfer from the NiAl to the Mo phase.

  10. Excimer laser synthesis of thin AlN coatings

    NASA Astrophysics Data System (ADS)

    Boulmer-Leborgne, C.; Thomann, A. L.; Andreazza, P.; Andreazza-Vignolle, C.; Hermann, J.; Craciun, V.; Echegut, P.; Craciun, D.

    1998-02-01

    A new technique for the production of thin AlN films on Al samples by direct laser synthesis is reported. This has the advantages of good adhesion, low temperature deposition and localisation. A metallic, pure Al sample is irradiated by an excimer laser under a nitrogen containing atmosphere at high intensity levels such that a plasma is formed above the sample. The active nitrogen atoms and ions contained in this plasma react with the hot melted Al surface resulting in the synthesis of an AlN layer. The influence of the incident laser fluence, nature and pressure of the ambient atmosphere and of the number of laser pulses on the chemical composition and crystalline structure of the synthesised layers is reported. Under optimised conditions a few ?m thick polycrystalline AlN layer, containing only a few percent oxygen and exhibiting high hardness and very good adhesion, has been prepared on Al.

  11. 26Al uptake and accumulation in the rat brain

    NASA Astrophysics Data System (ADS)

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

    1997-03-01

    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.

  12. Influence of overaging treatment on localized corrosion of Al 6056

    SciTech Connect

    Gullaumin, V.; Mankowski, G.

    2000-01-01

    The influence of T78 overaging treatment on the corrosion behavior of AL 6056 (UNS A96056) in 1 M sodium chloride (NaCl) solution was investigated. The overaged alloy presented the same localized corrosion mechanisms as Al 6056-T6. However, Al 6056-T78 coarse intermetallic Al-Mg-Si-containing particles were found to be more reactive than those in the Al 6056-T6 alloy and were nucleation sites for pits. Pitting and intergranular corrosion were dependent upon each other; intergranular corrosion nucleated on pit walls. A quantitative study showed that T78 overaging of Al 6056 offered a better resistance to intergranular corrosion compared to T6 peak-aging treatment. The overaged alloy will be able to replace the traditional Al 2024 because of the efficiency of this overaging treatment.

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

    SciTech Connect

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

    2008-06-26

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

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

    SciTech Connect

    Bartholomeusz, M.F.; Wert, J.A. ); Qibin Yang )

    1993-08-01

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

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

    PubMed

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

    2015-04-01

    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 Al3+, 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 Al3+ 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

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

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

    Low-frequency noise in AlGaN/GaN high electron mobility transistor (HEMT) heterostructures with additional AlN thin barrier layer is investigated. Transmission line model structures with different lengths of the conducting channel formed by polarization effects at the heterointerface of undoped AlGaN/AlN/GaN layers are studied. The measured noise demonstrates an unusual broadening of the generation-recombination components of the spectra. To explain the noise behaviour of the structure we consider a model taking into account peculiarities of the band structure of the interface with inserted AlN high molar fraction barrier layer.

  17. Influence of Content of Al2O3 on Structure and Properties of Nanocomposite Nb-B-Al-O films.

    PubMed

    Liu, Na; Dong, Lei; Dong, Lei; Yu, Jiangang; Pan, Yupeng; Wan, Rongxin; Gu, Hanqing; Li, Dejun

    2015-12-01

    Nb-B-Al-O nanocomposite films with different power of Al2O3 were successfully deposited on the Si substrate via multi-target magnetron co-sputtering method. The influences of Al2O3's content on structure and properties of obtained nanocomposite films through controlling Al2O3's power were investigated. Increasing the power of Al2O3 can influence the bombarding energy and cause the momentum transfer of NbB2. This can lead to the decreasing content of Al2O3. Furthermore, the whole films showed monocrystalline NbB2's (100) phase, and Al2O3 shaded from amorphous to weak cubic-crystalline when decreasing content of Al2O3. This structure and content changes were proof by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). When NbB2 grains were far from each other in lower power of Al2O3, the whole films showed a typical nanocomposite microstructure with crystalline NbB2 grains embedded in a matrix of an amorphous Al2O3 phase. Continuing increasing the power of Al2O3, the less content of Al2O3 tended to cause crystalline of cubic-Al2O3 between the close distances of different crystalline NbB2 grains. The appearance of cubic-crystallization Al2O3 can help to raise the nanocomposite films' mechanical properties to some extent. The maximum hardness and elastic modulus were up to 21.60 and 332.78 GPa, which were higher than the NbB2 and amorphous Al2O3 monolithic films. Furthermore, this structure change made the chemistry bond of O atom change from the existence of O-Nb, O-B, and O-Al bonds to single O-Al bond and increased the specific value of Al and O. It also influenced the hardness in higher temperature, which made the hardness variation of different Al2O3 content reduced. These results revealed that it can enhance the films' oxidation resistance properties and keep the mechanical properties at high temperature. The study highlighted the importance of controlling the Al2O3's content to prepare well-defined films with high mechanical properties and thermal stability. PMID:26597298

  18. An evaluation of the Qut Al-Qulub of Al-Makki with an annotated translation of his Kitab Al-Tawba 

    E-print Network

    Amin, W. Mohammed Azam ibn Mohammed

    1991-01-01

    This thesis seeks to study in depth the contribution to Sufism made by the little-known 4th/10th century figure Abu Talib al-Makki. The first chapter deals with an analysis of the life and works of al-Makki against the ...

  19. Evaluation of the Qu?t al-qulu?b of Al-Makki? with an annotated translation of his Kita?b Al-Tawba 

    E-print Network

    Amin, W. Mohammed Azam ibn Mohammed

    1991-01-01

    This thesis seeks to study in depth the contribution to Sufism made by the little-known 4th/10th century figure Abu? T?a?lib al-Makki?. The first chapter deals with an analysis of the life and works of al-Makki? against the background...

  20. Thermodynamic study of the gaseous molecules Al2N, AlN, and Al2N2 by Knudsen cell mass spectrometry

    NASA Astrophysics Data System (ADS)

    Meloni, G.; Gingerich, K. A.

    2000-12-01

    The Knudsen effusion mass spectrometric method has been employed to measure the equilibrium partial pressures of the Al2N molecule over the AlN-Au-graphite system. Theoretical computations were carried out to determine the structure, molecular parameters, and thermodynamic properties of Al2N. The partial pressures have been combined with the calculated thermal functions to determine the atomization enthalpy, ?aH0o, and enthalpy of formation, ?fH298.15o, in kJ mol-1, of 783.2±15 and 342.7±15 for Al2N, respectively. Upper values for the dissociation energy of AlN, D0o(AlN,g)?368±15 kJ mol-1, and for the atomization enthalpy of Al2N2, ?aH0o(Al2N2,g)?1402 kJ mol-1 have been obtained. These results are discussed and compared with recent theoretical literature values.

  1. 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

    2012-12-11

    ...: November 20, 2012. Hillary Rodham Clinton, Secretary of State. BILLING CODE 4710-10-P ..., the Secretary of State concludes that there is a sufficient factual basis to find that al-Qa'ida in... Secretary of State hereby amends the 2004 designation of al-Qa'ida in Iraq as a foreign...

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

    SciTech Connect

    Kaun, Stephen W.; Burke, Peter G.; Kyle, Erin C. H.; Speck, James S.; Wong, Man Hoi; Mishra, Umesh K.

    2012-12-24

    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.

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

    NASA Astrophysics Data System (ADS)

    Sugiura, Yohei; Honda, Tohru; Higashiwaki, Masataka

    2014-11-01

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

  4. In situ (?-Al2O3+ZrB2)/Al composites with network distribution fabricated by reaction hot pressing

    NASA Astrophysics Data System (ADS)

    Mokhnache, El Oualid; Wang, Gui-song; Geng, Lin; Balasubramaniam, Kaveendran; Henniche, Abdelkhalek; Ramdani, Noureddine

    2015-10-01

    In situ (?-Al2O3+ZrB2)/Al composites with network distribution were fabricated using low-energy ball milling and reaction hot pressing. Differential thermal analysis (DTA) was used to study the reaction mechanisms in the Al-ZrO2-B system. X-ray diffraction (XRD) and scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy (EDX) were used to investigate the composite phases, morphology, and microstructure of the composites. The effect of matrix network size on the microstructure and mechanical properties was investigated. The results show that the optimum sintering parameters to complete reactions in the Al-ZrO2-B system are 850°C and 60 min. In situ-synthesized ?-Al2O3 and ZrB2 particles are dispersed uniformly around Al particles, forming a network microstructure; the diameters of the ?-Al2O3 and ZrB2 particles are approximately 1-3 ?m. When the size of Al powder increases from 60-110 ?m to 150-300 ?m, the overall surface contact between Al powders and reactants decreases, thereby increasing the local volume fraction of reinforcements from 12% to 21%. This increase of the local volume leads to a significant increase in microhardness of the in situ (?-Al2O3-ZrB2)/Al composites from Hv 163 to Hv 251.

  5. Structure and magnetic properties of Ce?(Ni/Al/Ga)??—A new phase with the La?Al?? structure type

    DOE PAGESBeta

    Janka, Oliver; Shang, Tian; Baumbach, Ryan E.; Bauer, Eric D.; Thompson, Joe D.; Kauzlarich, Susan M.

    2015-03-01

    Single crystals of Ce?(Ni/Al/Ga)?? were obtained from an Al flux reaction. Single crystals of the title compound crystallizing in the orthorhombic space group Immm (No. 71, Z = 2) with a = 436.38(14), b = 1004.5(3) and c = 1293.4(4) pm. This is a standardized unit cell of the previously published La?Al?? structure type. Wavelength dispersive microprobe provides the composition of Ce?.?????Ni?.?????Al?.?????Ga?.?????. Single crystal refinement provides the composition Ce?Ni?.??Al?.??Ga?.?? with substitution of the Ni and Ga on the Al1 and Al4 sites with the Al2 and Al3 solely occupied by Al. Magnetic susceptibility measurements reveal antiferromagnetic ordering with TN =more »4.8 K and there is no evidence for a ferromagnetic ordering that has been reported for Ce?Al??. The effective magnetic moment was found to be ?eff = 1.9?B/Ce, which is lower than the expected value for trivalent Ce (2.54?B/Ce).« less

  6. Structure and magnetic properties of Ce?(Ni/Al/Ga)??—A new phase with the La?Al?? structure type

    SciTech Connect

    Janka, Oliver; Shang, Tian; Baumbach, Ryan E.; Bauer, Eric D.; Thompson, Joe D.; Kauzlarich, Susan M.

    2015-03-01

    Single crystals of Ce?(Ni/Al/Ga)?? were obtained from an Al flux reaction. Single crystals of the title compound crystallizing in the orthorhombic space group Immm (No. 71, Z = 2) with a = 436.38(14), b = 1004.5(3) and c = 1293.4(4) pm. This is a standardized unit cell of the previously published La?Al?? structure type. Wavelength dispersive microprobe provides the composition of Ce?.?????Ni?.?????Al?.?????Ga?.?????. Single crystal refinement provides the composition Ce?Ni?.??Al?.??Ga?.?? with substitution of the Ni and Ga on the Al1 and Al4 sites with the Al2 and Al3 solely occupied by Al. Magnetic susceptibility measurements reveal antiferromagnetic ordering with TN = 4.8 K and there is no evidence for a ferromagnetic ordering that has been reported for Ce?Al??. The effective magnetic moment was found to be ?eff = 1.9?B/Ce, which is lower than the expected value for trivalent Ce (2.54?B/Ce).

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

    SciTech Connect

    Ichikawa, S. Iwata, Y.; Funato, M.; Kawakami, Y.; Nagata, S.

    2014-06-23

    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.

  8. X-ray high-pressure study of Ti2AlN and Ti2AlC

    NASA Astrophysics Data System (ADS)

    Manoun, Bouchaib; Zhang, F. X.; Saxena, S. K.; El-Raghy, T.; Barsoum, M. W.

    2006-09-01

    The lattice parameters of Ti2AlN and Ti2AlC powders were measured as a function of pressure up to ?50 GPa, using a synchrotron radiation source and a diamond anvil cell. No phase transformations were observed. As for most related layered carbides and nitrides, such as Ti4AlN3 and Ti3SiC2, the compressibilities of Ti2AlN and Ti2AlC along the c-axes are larger than those along the a-axes. The bulk modulus of Ti2AlC at 186±2 GPa, is ?10% higher than that of Ti2AlN at 169±3 GPa.

  9. Formation of thin AlN films on NiAl(001) upon thermal decomposition of ammonia

    NASA Astrophysics Data System (ADS)

    Gassmann, P.; Bartolucci, F.; Franchy, R.

    1995-06-01

    The formation of thin AlN films on NiAl(001) has been studied by means of high resolution electron energy loss spectroscopy (HREELS), low-energy electron diffraction (LEED), and Auger electron spectroscopy. The AlN films were grown by the adsorption of NH3 on NiAl(001) at T=80 K and subsequent thermal decomposition at elevated temperatures. After annealing to T=1250 K, a distinct LEED pattern appears which exhibits pseudo-twelvefold symmetry. This indicates the formation of two hexagonal domains of AlN which are rotated by 90° with respect to each other. HREEL spectra of the ordered AlN film show a Fuchs-Kliewer phonon mode at 865 cm-1 in good agreement with theoretical spectra calculated on the base of the dielectric theory. The electronic energy gap of the thin AlN films is determined to be Eg?6.1 eV.

  10. Mechanical behaviour of an Al-matrix composite reinforced with nanocrystalline Al-coated B4C particulates

    NASA Astrophysics Data System (ADS)

    Ye, J.; Han, B. Q.; Schoenung, J. M.

    2006-11-01

    In metal-matrix composites (MMCs), interfacial bonding between the metal matrix and the ceramic reinforcement plays a crucial role in their mechanical performance. In the present study, B4C particles were cryomilled with an Al alloy to produce a composite powder, in which the B4C was uniformly distributed in nanocrystalline Al. The cryomilling developed a strong bond between the B4C and the Al, allowing the nanocrystalline Al to act as a coating with a strong ceramic-metal interface. This cryomilled composite powder was then introduced, as a reinforcement, into a conventional Al alloy to strengthen the material. After consolidation, the result was a bulk Al-matrix composite reinforced with B4C particles encapsulated in nanocrystalline Al. This composite exhibits greatly improved strength and stiffness.

  11. In Situ Al Based Composites Fabricated in Al-SiO2-C System by Reaction Sintering

    NASA Astrophysics Data System (ADS)

    Mokhnache, El Oualid; Wang, Guisong; Geng, Lin; Kaveendran, Balasubramaniam; Henniche, Abdelkhalek; Ramdani, Noureddine

    2015-07-01

    In situ Al-based composites with different SiO2/C/Al molar ratios were fabricated by reaction hot pressing. Differential scanning calorimetry (DSC) was used to investigate the reaction mechanisms in the Al-SiO2-C system. X-ray diffraction results revealed that no new resultant phase was observed below the melting temperature of aluminum except the SiO2, C and Al phases. Heating at different synthesis temperatures showed that, up to 1000°C with a holding time of 1 h, the reactions in the Al-SiO2-C system took place completely, where the final products were Al2O3, SiC, Al4C3 and Si. Microstructural observation showed that the in situ synthesized Al2O3, SiC, Al4C3, and Si were dispersed uniformly and had fine sizes less than 2 µm. The formed interfaces between the reinforcements and Al matrix are clean and free from any interfacial phase. During cooling, the synthesized Si formed a multilayer growth in the (111) direction. When the SiO2/C/Al molar ratio was (6/3/9), more Al2O3 and Si were produced along with the complete prevention of Al4C3 in the Al-SiO2-C system. The yield strength, ultimate tensile strength and Brinell hardness of the in situ fabricated composites are significantly higher than those of pure aluminum matrix, with a decrease of ductility. Mechanisms governing the tensile fracture process are also discussed.

  12. Sulfidation-Oxidation Behavior of FeCrAl and TiCrAl and the Third-Element Effect

    SciTech Connect

    Brady, Michael P; Tortorelli, Peter F; More, Karren Leslie; Walker, Larry R

    2010-01-01

    Short-term sulfidation-oxidation exposures were conducted under high pS2 and low pO2 conditions for TiCrAl and FeCrAl alloys at 600 and 800 C. Low mass gains and submicron Al-rich oxide scales were formed on the TiCrAl, while high mass gains and FeS-based scale formation were observed for FeCrAl. Based on the good behavior of the TiCrAl, third-element effect additions of Cr are not inherently detrimental under sulfidation-oxidation conditions. Rather, differences in the mechanistic action of the third-element addition of Cr between FeCrAl and TiCrAl alloys and its relevance to low oxygen potential sulfidation-oxidation environments were the key factors in determining whether or not a protective alumina scale was established. For FeCrAl, no internal oxidation of Al was observed, which suggested that effects related to secondary gettering were not sufficient to yield protective Al2O3 formation in these environments. Rather, it was proposed that additional third-element effect benefits of Cr based on the existence of solid solutions among Al, Cr, and Fe oxides to mitigate rapid transient Fe-oxide formation were rendered ineffective because FeS formation was thermodynamically favored over Fe-oxide in the environment. In the case of TiCrAl, the stability of Ti-oxide in the sulfidation-oxidation environment and the non-classical third-element effects of Cr on promoting protective Al2O3 scale led to good corrosion resistance.

  13. Unintentional gallium incorporation in AlN and its impact on the electrical properties of GaN/AlN and GaN/AlN/AlGaN heterostructures

    NASA Astrophysics Data System (ADS)

    Li, Haoran; Keller, Stacia; Chan, Silvia H.; Lu, Jing; DenBaars, Steven P.; Mishra, Umesh K.

    2015-05-01

    Thin AlN interlayers are widely used in (In,Al,Ga)N based high-electron-mobility transistors to improve the mobility of the two-dimensional electron gas forming at the GaN/(In,Al,Ga)N interface. AlN layers grown by metal-organic chemical vapor deposition, however, were recently shown to contain high amounts of gallium caused by carry over reactions, resulting in AlxGa1-xN layers with x ˜ 0.5 under typical deposition conditions. By modifying the AlN growth conditions in this study, layers with an Al mole fraction up to 0.78 were obtained. The unintentional Ga incorporation had a negligible effect on the electronic properties of GaN/AlN/AlGaN structures with nominally 0.7 nm thick AlN interlayer and sheet carrier densities in the order of 1 × 1013 cm-3. It resulted, however, in low electron mobility values for samples with thicker nominal AlN layers and/or higher sheet carrier densities.

  14. Texture development of ARB processed Mg/Al multilayers

    NASA Astrophysics Data System (ADS)

    Brokmeier, H.-G.; Chang, H.; Gan, W. M.; Zheng, M. Y.; Wu, K.

    2010-07-01

    Our work deals with accumulative roll bonding (ARB) of pure Mg sheet (0.9mm thickness) and of Al5052 sheet (0.5mm). A stacking of Al-Mg-Al was firstly rolled to 50% reduction at 400°C and secondly ARB has been processed up to 3 cycles. In such multilayers as well as highly mixed composites of two-phased system texture development, phase reactions and strain accumulation are of basic interest, which needs a combination of different experimental methods for characterization. The present paper deals with the global texture evolution measured by thermal neutrons to average always over the whole sample thickness, SEM and optical microscopy indicates the macroscopic development of Mg and Al layers. The initial materials show typical and strong basal plane texture of hexagonal Mg (17.9mrd) and a recrystallization texture of cubic Al (8.5mrd). Co-deformation of Al/Mg/Al leads to strong decrease of both textures, whereas Mg has always a much stronger texture than Al5052. ARB processing produces only weak Al-textures. After sandwich-rolling and 1 cycle ARB rotated cube is observed in Al5052, which does not exist after 2 and 3 cycles of ARB.

  15. Gate-Tunable Electron Transport Phenomena in Al-Ge?111?-Al Nanowire Heterostructures.

    PubMed

    Brunbauer, Florian M; Bertagnolli, Emmerich; Lugstein, Alois

    2015-11-11

    Electrostatically tunable negative differential resistance (NDR) is demonstrated in monolithic metal-semiconductor-metal (Al-Ge-Al) nanowire (NW) heterostructures integrated in back-gated field-effect transistors (FETs). Unambiguous signatures of NDR even at room temperature are attributed to intervalley electron transfer. At yet higher electric fields, impact ionization leads to an exponential increase of the current in the ?111? oriented Ge NW segments. Modulation of the transfer rates, manifested as a large tunability of the peak-to-valley ratio (PVR) and the onset of impact ionization is achieved by the combined influences of electrostatic gating, geometric confinement, and heterojunction shape on hot electron transfer and by electron-electron scattering rates that can be altered by varying the charge carrier concentration in the NW FETs. PMID:26426433

  16. Synthesis of Al/Al sub 3 Ti two-phase alloys by mechanical alloying

    SciTech Connect

    Srinivasan, S.; Chen, S.R.; Schwarz, R.B.

    1991-01-01

    We have mechanically alloyed mixtures of elemental powders to prepare fine-grain two-phase A1/A1{sub 3}Ti powders at the compositions A1-20at% Ti and Al-10at% Ti. Hexane was used to prevent agglomeration of the powder during MA. Carbon from the decomposition of the hexane was incorporated in the powder. It reacted with Ti to form a fine dispersion of carbides in the final hot-pressed compact. We consolidated the mechanically alloyed powders by hot-pressing. Yield strength and ductility were measured in compression. At 25{degree}C, the compressive yield strengths were 1.25 and 0.6 GPa for the A1-20at% Ti and Al-10at% Ti alloys, respectively. The ductility of the A1-10at% Ti alloy exceeded 20% for 25 < T < 500{degree}C. 25 refs., 6 figs.

  17. Missing superconductivity in BaAlSi with the AlB 2 type structure

    NASA Astrophysics Data System (ADS)

    Yamanaka, Shoji; Otsuki, Teruyoshi; Ide, Takayuki; Fukuoka, Hiroshi; Kumashiro, Ryotaro; Rachi, Takeshi; Tanigaki, Katsumi; Guo, FangZhun; Kobayashi, Keisuke

    2007-01-01

    The solid solutions BaAl 1- xSi 1+ x (0 ? x ? 0.5) were prepared. The compound with the stoichiometric composition ( x = 0) did not show superconductivity as reported by other investigators, but the solid solutions with x > 0 became superconductors with a transition temperature Tc = 2.8 K. The comparison of the lattice parameters with those of the other isotypic ternary superconductors MAlSi (M = Ca, Sr) suggested that the superconductivity could be related to the lattice parameter within the (AlSi) plane rather than the interlayer spacing. The band structures near the Fermi level of MAlSi (M = Ca, Sr, Ba) were measured using soft X-ray photoelectron spectroscopy, which were in good agreement with the calculated ones, confirming that the contribution of the d orbitals of the alkaline-earth metals were predominant in the conduction bands.

  18. Gate-Tunable Electron Transport Phenomena in Al–Ge?111?–Al Nanowire Heterostructures

    PubMed Central

    2015-01-01

    Electrostatically tunable negative differential resistance (NDR) is demonstrated in monolithic metal–semiconductor–metal (Al–Ge–Al) nanowire (NW) heterostructures integrated in back-gated field-effect transistors (FETs). Unambiguous signatures of NDR even at room temperature are attributed to intervalley electron transfer. At yet higher electric fields, impact ionization leads to an exponential increase of the current in the ?111? oriented Ge NW segments. Modulation of the transfer rates, manifested as a large tunability of the peak-to-valley ratio (PVR) and the onset of impact ionization is achieved by the combined influences of electrostatic gating, geometric confinement, and heterojunction shape on hot electron transfer and by electron–electron scattering rates that can be altered by varying the charge carrier concentration in the NW FETs. PMID:26426433

  19. High Performance Polarized Electron Photocathodes Based on InGaAlAs/AlGaAs Superlattices

    SciTech Connect

    Mamaev, Yu.

    2004-12-10

    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.

  20. Strange meson production in Al+Al collisions at 1.9A GeV

    E-print Network

    P. Gasik; K. Piasecki; N. Herrmann; Y. Leifels; T. Matulewicz; A. Andronic; R. Averbeck; V. Barret; Z. Basrak; N. Bastid; M. L. Benabderrahmane; M. Berger; P. Buehler; M. Cargnelli; R. ?aplar; P. Crochet; O. Czerwiakowa; I. Deppner; P. Dupieux; M. Dželalija; L. Fabbietti; Z. Fodor; I. Gašpari?; Y. Grishkin; O. N. Hartmann; K. D. Hildenbrand; B. Hong; T. I. Kang; J. Kecskemeti; Y. J. Kim; M. Kirejczyk; M. Kiš; P. Koczon; R. Kotte; A. Lebedev; A. Le Fèvre; J. L. Liu; X. Lopez; V. Manko; J. Marton; R. Münzer; M. Petrovici; F. Rami; A. Reischl; W. Reisdorf; M. S. Ryu; P. Schmidt; A. Schüttauf; Z. Seres; B. Sikora; K. S. Sim; V. Simion; K. Siwek-Wilczy?ska; V. Smolyankin; K. Suzuki; Z. Tymi?ski; P. Wagner; I. Weber; E. Widmann; K. Wi?niewski; Z. G. Xiao; I. Yushmanov; Y. Zhang; A. Zhilin; V. Zinyuk; J. Zmeskal

    2015-12-22

    The production of K$^+$, K$^-$ and $\\varphi$(1020) mesons is studied in Al+Al collisions at beam energy of 1.9A GeV which is close or below the production threshold in NN reactions. Inverse slopes, anisotropy parameters, and total emission yields of K$^{\\pm}$ mesons are obtained. A comparison of the ratio of kinetic energy distributions of K$^-$ and K$^+$ mesons to the HSD transport model calculations suggests that the inclusion of in-medium modifications of kaon properties is necessary to reproduce the ratio. The inverse slope and total yield of $\\phi$ mesons are deduced. The contribution to K$^-$ production from $\\phi$ meson decays is found to be [17 $\\pm$ 3 (stat) $^{+2}_{-7}$ (syst)] %. The results are in line with previous K$^{\\pm}$ and $\\phi$ data obtained for different colliding systems at similar incident beam energies.

  1. Strange meson production in Al+Al collisions at 1.9A GeV

    E-print Network

    Gasik, P; Herrmann, N; Leifels, Y; Matulewicz, T; Andronic, A; Averbeck, R; Barret, V; Basrak, Z; Bastid, N; Benabderrahmane, M L; Berger, M; Buehler, P; Cargnelli, M; ?aplar, R; Crochet, P; Czerwiakowa, O; Deppner, I; Dupieux, P; Dželalija, M; Fabbietti, L; Fodor, Z; Gašpari?, I; Grishkin, Y; Hartmann, O N; Hildenbrand, K D; Hong, B; Kang, T I; Kecskemeti, J; Kim, Y J; Kirejczyk, M; Kiš, M; Koczon, P; Kotte, R; Lebedev, A; Fèvre, A Le; Liu, J L; Lopez, X; Manko, V; Marton, J; Münzer, R; Petrovici, M; Rami, F; Reischl, A; Reisdorf, W; Ryu, M S; Schmidt, P; Schüttauf, A; Seres, Z; Sikora, B; Sim, K S; Simion, V; Siwek-Wilczy?ska, K; Smolyankin, V; Suzuki, K; Tymi?ski, Z; Wagner, P; Weber, I; Widmann, E; Wi?niewski, K; Xiao, Z G; Yushmanov, I; Zhang, Y; Zhilin, A; Zinyuk, V; Zmeskal, J

    2015-01-01

    The production of K$^+$, K$^-$ and $\\varphi$(1020) mesons is studied in Al+Al collisions at beam energy of 1.9A GeV which is close or below the production threshold in NN reactions. Inverse slopes, anisotropy parameters, and total emission yields of K$^{\\pm}$ mesons are obtained. A comparison of the ratio of kinetic energy distributions of K$^-$ and K$^+$ mesons to the HSD transport model calculations suggests that the inclusion of in-medium modifications of kaon properties is necessary to reproduce the ratio. The inverse slope and total yield of $\\phi$ mesons are deduced. The contribution to K$^-$ production from $\\phi$ meson decays is found to be [17 $\\pm$ 3 (stat) $^{+2}_{-7}$ (syst)] %. The results are in line with previous K$^{\\pm}$ and $\\phi$ data obtained for different colliding systems at similar incident beam energies.

  2. Frictional sliding at a compressed polycrystalline 50 nm grain size Al-Al interface

    NASA Astrophysics Data System (ADS)

    Hammerberg, J. E.; Ravelo, R. J.; Germann, T. C.

    2015-03-01

    We present the results of large-scale NEMD simulations for a polycrystalline Al-Al interface sliding at a relative velocity of 60 m/s and a pressure of 15 GPa with a boundary temperature of 300K. The sample consisted of annealed grains, 125 grains on either side of the initial sliding interface, with dimensions of 2x(236) nm in the normal direction and 236 nm in the periodic sliding and transverse directions. Simulation times were of order 20 ns and the sample had 1.8B atoms interacting with an Al-EAM potential. The initial grain structure evolves to a complex dynamic steady state grain morphology that is very different from the initial grain structure and is characterized by large plastic strains and strain rates in a deformation region of thickness 150 nm at the interface in the normal direction. The steady state shows a sequence of grain growth and refinement and a highly strained graded microstructure. This behavior is similar to that seen in simulations for 13 and 20 nm grains and a mesoscale model that takes into account the large plastic strains and strain rates, and the size of the deformation region is able to reproduce the values of the frictional force per unit area. This work was performed under the auspices of the U.S. Dept. of Energy under Contract DE-AC52-06NA25396. The support of the LANL ASC-PEM program is gratefully acknowledged.

  3. Impact of SiO2 on Al-Al thermocompression wafer bonding

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  4. Modulated magnetism in PrPtAl

    NASA Astrophysics Data System (ADS)

    Abdul-Jabbar, Gino; Sokolov, Dmitry A.; O'Neill, Christopher D.; Stock, Christopher; Wermeille, Didier; Demmel, Franz; Krüger, Frank; Green, Andrew G.; Lévy-Bertrand, Florence; Grenier, Béatrice; Huxley, Andrew D.

    2015-04-01

    The transition between paramagnetism and ferromagnetism is the paradigm for a continuous phase transition at finite temperature. When such a transition is tuned to zero temperature in clean materials, the growth of low-energy zero-point fluctuations potentially drives an array of phenomena, including the formation of novel states such as non-conventional superconductivity. Experimentally, the growth of the fluctuations, however, is curtailed and the transition becomes discontinuous as its temperature is reduced. This is understood to arise from non-analytic corrections to the free energy that always occur. In a recent theory, changes of the excitation spectrum are self-consistently considered alongside the ground state. This analysis reveals that a transition to a new state may be an alternative outcome. As the excitation spectrum (the `disorder’) is pivotal to promoting the new `order’ this mechanism is referred to as `order by disorder’. Here, we report the discovery of modulated order in PrPtAl, consistent with complex spirals, at the boundary between paramagnetism and ferromagnetism, giving the first clear experimental realization of such a state.

  5. Mechanical spectroscopy of Al-Mg alloys

    NASA Astrophysics Data System (ADS)

    Golovin, I. S.; Bychkov, A. S.; Medvedeva, S. V.; Hu, X. S.; Zheng, M. Y.

    2013-04-01

    The internal friction of deformed, annealed, and quenched Al-Mg alloys with Mg contents of 0-12 wt % has been studied as a function of temperature. The measurements have been performed in the range of 25-580°C at 0.3-30 Hz using a DMA Q800 TA Instruments dynamic mechanical analyzer at the maximum amplitude of deformation ?0 = 5 × 10-5. In annealed alloys with Mg contents up to 5 %, a relaxation IF peak with activation parameters (activation energy H ? 1.7-2.1 eV) has been detected. In alloys with 8-12% Mg, this relaxation peak is absent and, at a lower temperature, another IF peak appears (with an activation energy H of about 1 eV), which is interpreted as the Zener peak in terms of the combination of activation parameters. The article discusses the nature of these peaks and the influence of alloying on the relaxation mechanisms. In cold-worked alloys, an IF pseudo-peak takes place, which is related to the recrystallization of samples, and its temperature position in the alloys that contain more than 5% Mg depends not only on the degree of deformation, but also on the dissolution temperature of the ? phase.

  6. 3DGRAPE/AL User's Manual

    NASA Technical Reports Server (NTRS)

    Sorenson, Reese L.; Alter, Stephen J.

    1995-01-01

    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.

  7. Charging effect of aluminum nitride thin films containing Al nanocrystals.

    PubMed

    Liu, Y; Chen, T P; Ding, L; Wong, J I; Yang, M; Liu, Z; Li, Y B; Zhang, S

    2010-01-01

    In this work, the Al-rich AIN thin film is deposited on Si substrate by radio frequency (RF) sputtering to form a metal-insulator-semiconductor (MIS) structure. Al nanocrystals (nc-Al) are formed and embedded in the AIN thin film. Charge trapping/detrapping in the nc-Al leads to a shift in the flat-band voltage (VFB) of the MIS structure. The charge storage ability of the AIN thin films containing Al nanocrystals provides the possibility of memory applications. On the other hand, charge trapping in nc-Al reduces the current conduction because of the breaking of some tunneling paths due to Coulomb blockade effect and the current conduction evolves with a trend towards one-dimensional transport. PMID:20352898

  8. Diffusion markers in Al/metal thin-film reactions

    NASA Astrophysics Data System (ADS)

    Colgan, E. G.; Mayer, J. W.

    1986-10-01

    A method was developed to measure the diffusing species in aluminide formation in cases where the reacted layer is laterally nonuniform. Rutherford backscattering spectrometry was used to determine the amount of each metal (atoms/cm 2) over the marker at different stages of the annealing sequence. This overlayer measurement gave equivalent results when compared with conventional energy width and marker displacement analysis in suicide formation. By using a tungsten marker diluted with Al, instead of a pure tungsten film, we minimized barrier problems. The marker was sandwiched between coevaporated layers of the compound being studied to reduce interface drag. We found for the growth of TiAl 3 and NiAl 3 that Al is the dominant moving species in agreement with previous results in thin-film (TiAl 3) and bulk (NiAl 3) measurements.

  9. A fruitful endeavor: modeling ALS in the fruit fly.

    PubMed

    Casci, Ian; Pandey, Udai Bhan

    2015-05-14

    For over a century Drosophila melanogaster, commonly known as the fruit fly, has been instrumental in genetics research and disease modeling. In more recent years, it has been a powerful tool for modeling and studying neurodegenerative diseases, including the devastating and fatal amyotrophic lateral sclerosis (ALS). The success of this model organism in ALS research comes from the availability of tools to manipulate gene/protein expression in a number of desired cell-types, and the subsequent recapitulation of cellular and molecular phenotypic features of the disease. Several Drosophila models have now been developed for studying the roles of ALS-associated genes in disease pathogenesis that allowed us to understand the molecular pathways that lead to motor neuron degeneration in ALS patients. Our primary goal in this review is to highlight the lessons we have learned using Drosophila models pertaining to ALS research. This article is part of a Special Issue entitled ALS complex pathogenesis. PMID:25289585

  10. Reactive codoping of GaAlInP compound semiconductors

    DOEpatents

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

    2008-02-12

    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.

  11. Cost-Effective TiAl based Materials

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  12. Hydrodeoxygenation of Guaiacol Over Pt/Al-SBA-15 Catalysts.

    PubMed

    Yu, Mi Jin; Park, Sung Hoon; Jeon, Jong-Ki; Ryu, Changkook; Sohn, Jung Min; Kim, Sang Chai; Park, Young-Kwon

    2015-01-01

    Upgrading of bio-oil through catalytic hydrodeoxygenation (HDO) reaction was investigated for guaiacol as a model compound. A batch reactor was used for the reaction condition of 40 bar and 250 degrees C. The target product was cyclohexane. Pt/Al-SBA-15 with the Si/Al ratios of 20, 40, and 80 and Pt/HZSM-5 were used as the catalyst. The SBA-15 catalysts were characterized by N2 adsorption-desorption, X-ray diffraction analysis, and temperature programmed desorption of ammonia. The order of cyclohexane yield was Pt/Al-SBA-15 (Si/Al = 20) > Pt/Al-SBA-15(40) > Pt/Al-SBA-15 (80), indicating that the quantity of acid sites plays an important role in the HDO reaction. On the other hand, Pt/HZSM-5 led to a very low cyclohexane yield, in spite of its abundant strong acid sites, due to its small pore size. PMID:26328395

  13. Direct dynamic nuclear polarization targeting catalytically active (27)Al sites.

    PubMed

    Lund, Alicia; Hsieh, Ming-Feng; Siaw, Ting-Ann; Han, Song-I

    2015-09-23

    Here we present a systematic study of direct (27)Al Dynamic Nuclear Polarization (DNP) as induced by three different mono-radical probes with side groups of varying charge states. By employing 4-amino TEMPO that adsorbs to negatively charged surface sites of Al-SBA-15, we achieve a (27)Al signal enhancement factor of ?13 compared to a signal enhancement factor of ?3-4 from mono-radicals that do not adsorb as strongly to the surfaces of Al-SBA-15, here 4-carboxy- and 4-hydroxy-TEMPO. By performing Electron Spin Echo Envelope Modulation (ESEEM) experiments and continuous wave (cw) Electron Paramagnetic Resonance (EPR) lineshape analysis using various nitroxide probes imbibed in Al-SBA-15, we find that direct (27)Al DNP enhancements achieved with different spin probes can be attributed to proximity and local concentration of the spin probes to aluminum on the surface of mesoporous alumina-silica. PMID:26365719

  14. Origin of ordering in B2-type transition-metal aluminides: Comparative study of the defect properties of PdAl, NiAl, and FeAl

    NASA Astrophysics Data System (ADS)

    Fu, C. L.

    1995-08-01

    The physical mechanism for ordering and the properties of lattice defects in B2-type transition-metal (TM) aluminides are presented. It is shown that the size effect is inadequate in explaining the defect structure (and ordering) in these intermetallics. Such is the case evident in the prototypical example of PdAl, which is found to exhibit all the physical characteristics of strongly ordered alloys even though the difference in atomic radii between constituent Pd and Al atoms is very small. We obtain a high heat of formation, high antiphase boundary energies associated with the partial 1/2<111> slip, and the existence of triple defect (for the point defect structure) in PdAl. Comparative analyses are presented for PdAl, NiAl, and FeAl, and results reveal that the electronic structure at the TM sites plays a decisive role in the energetics (and types) of defects. The strong ordering in late TM aluminides of the B2 type is due to the lack of electronic screening from the TM d band to compensate the energetically unfavorable nearest-neighbor interaction between Al atoms when ordering is disrupted.

  15. Interfacial and electrical characterization of HfO2/Al2O3/InAlAs structures

    NASA Astrophysics Data System (ADS)

    Wu, Li-fan; Zhang, Yu-ming; Lu, Hong-liang; Zhang, Yi-men

    2015-11-01

    The HfO2/Al2O3 double layer has been deposited by the atomic layer deposition (ALD) technique to a InAlAs epitaxial layer. The chemical composition at the interface was revealed by angle-resolved X-ray photoelectron spectroscopy (XPS). The electrical properties of the ALD-HfO2/Al2O3/InAlAs metal–oxide–semiconductor (MOS) capacitor have been investigated and compared with those of the ALD-HfO2/InAlAs capacitor. It is demonstrated that the insertion of the Al2O3 layer can decrease interfacial oxidation and trap charge formation. Compared with the HfO2/InAlAs capacitor, the HfO2/Al2O3/InAlAs capacitor exhibits better electrical properties with reduced hysteresis and decreasing stretch-out of the capacitance–voltage (C–V) characteristics, and the oxide trapped charge (Qot) value is significantly decreased after inserting the Al2O3 interlayer.

  16. 93Nb- and 27Al-NMR/NQR studies of the praseodymium based PrNb2Al20

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  18. TEM and HREM study of Al3Zr precipitates in an Al-Mg-Si-Zr alloy.

    PubMed

    Lityñska, L; Abou-Ras, D; Kostorz, G; Dutkiewicz, J

    2006-09-01

    The structure of Al(3)Zr precipitates in Al-1.0Mg-0.6Si-0.5Zr (in wt.%) alloy was investigated using conventional transmission electron microscopy (TEM) and high-resolution TEM (HREM). After annealing of the alloy in the temperature range 450-540 degrees C, spherical precipitates of metastable L1(2)-Al(3)Zr phase appeared nearly homogeneously within the matrix, and elongated particles were found at grain boundaries. L1(2)-structured Al(3)Zr were about 20-30 nm in diameter and coherent with the matrix. Inside some of them, planar faults parallel to {100} planes were revealed by use of HREM. Most probably, these faults are an indication of the transition stage of transformation to the stable D0(23)-type Al(3)Zr phase. The elongated precipitates (about 100 nm) were identified as D0(22)-type Al(3)Zr. Energy-dispersive X-ray analysis showed that they contain, apart from Al, mainly Zr with small amounts of Si. The substitution of Al by Si increased the stability of the D0(22)-Al(3)Zr as compared with D0(23)-Al(3)Zr. PMID:17059525

  19. 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

    Burge, Stephen Russell

    2010-01-01

    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 ...

  20. Banded structures in directionally solidified Ti-52Al alloys

    SciTech Connect

    Ramanujan, R.V. ); Bi, Y.; Xu, Q.; Abell, J.S. . School of Metallurgy and Materials)

    1994-03-15

    The authors report their results on the structure and chemistry of ingots and directionally solidified Ti-48Al and Ti-52Al alloys. Through the banding behavior, quantitative analysis of parts of the high temperature phase field in near-equiatomic Ti-Al alloys is obtained. A possible explanation for certain puzzling and unexplained observations by Oliver is presented. Optical microscopy, electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used in this investigation.

  1. News: Teatro al Sur y la escena Argentina

    E-print Network

    2000-04-01

    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. En ella diversos creadores... 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 esta actitud minimalista a la...

  2. Radiation Hard AlGaN Detectors and Imager

    SciTech Connect

    2012-05-01

    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.

  3. Spectra of surface plasmon polariton enhanced electroluminescence from electroformed Al-Al{sub 2}O{sub 3}-Ag diodes

    SciTech Connect

    Hickmott, T. W.

    2015-03-07

    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-Al{sub 2}O{sub 3}-Ag diodes with anodic Al{sub 2}O{sub 3} 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-Al{sub 2}O{sub 3}-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-Al{sub 2}O{sub 3} interface with radiative defect centers in Al{sub 2}O{sub 3}. 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 Al{sub 2}O{sub 3} thickness for Al-Al{sub 2}O{sub 3}-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 Al{sub 2}O{sub 3} when EL photons interact with electrons in Ag or Al to form surface plasmon polaritons at the Al{sub 2}O{sub 3}-Ag or Al{sub 2}O{sub 3}-Al interface. El intensity is a maximum at 2.0–2.2?eV for Al-Al{sub 2}O{sub 3}-Ag diodes with Al{sub 2}O{sub 3} thicknesses between 12?nm and 18?nm. EL in diodes with 12?nm or 14?nm of Al{sub 2}O{sub 3} is enhanced by factors of 8–10 over EL from a diode with 18?nm of Al{sub 2}O{sub 3}. 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-Al{sub 2}O{sub 3}-Ag diode with 12?nm of Al{sub 2}O{sub 3}; it had EL intensity 100 times greater at 2.15?eV than the diode with 18?nm of Al{sub 2}O{sub 3}. EL intensity for photons with energies greater than 2.6?eV is nearly the same for all diodes.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    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.

  5. Suvorova et al., 2009 Cytoprotective Nrf2 pathway is induced

    E-print Network

    Capecchi, Mario R.

    et al., 2008) and cytoplasmic Txnrd1/Txn1-dependent Prxs actively detoxify hydrogen peroxide thioredoxin reductases (Txnrd), glutathione reductase (GSR), superoxide dismutase, catalase, peroxiredoxins

  6. al-Qaida Strategy, Ideology, Doctrine, and Media

    SciTech Connect

    Dr. Jarret Brachman

    2010-06-29

    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.

  7. Compatibility of Fe-40Al with various fibers

    NASA Technical Reports Server (NTRS)

    Draper, S. L.; Gaydosh, D. J.; Nathal, M. V.; Misra, A. K.

    1990-01-01

    Chemical reaction can occur at the fiber/matrix interface of intermetallic matrix composites, leading to a degradation of mechanical properties. Fe-40Al matrix composites were fabricated using SiC, B, W, Mo-base, and Al2O3 fibers. Composite samples were heat treated up to 1500 K to study the reaction kinetics, and reaction rates were determined from reaction zone thickness measurements. The Al2O3 and W fibers were found to be compatible with the Fe-40Al matrix, while the Mo-based fibers reacted moderately and the B and SiC fibers reacted severely. Experimental results are compared to theoretical thermodynamic predictions.

  8. Thermal conductivity modeling of U-Mo/Al dispersion fuel

    NASA Astrophysics Data System (ADS)

    Kim, Yeon Soo; Cho, Byoung Jin; Sohn, Dong-Seong; Park, Jong Man

    2015-11-01

    A dataset for the thermal conductivity of U-Mo/Al dispersion fuel made available by KAERI was reanalyzed. Using this dataset, an analytical model was obtained by expanding the Bruggeman model. The newly developed model incorporates thermal resistances at the interface between the U-Mo particles and the Al matrix and the defects within the Al matrix (grain boundaries, cracks, and dislocations). The interfacial resistances are expressed as functions of U-Mo particle size and Al grain size obtained empirically by fitting to measured data from KAERI. The model was then validated against an independently measured dataset from ANL.

  9. Interdiffusion and Intrinsic Diffusion in the Mg-Al System

    SciTech Connect

    Brennan, Sarah; Bermudez, Katrina; Sohn, Yong Ho; Kulkarni, Nagraj S

    2012-01-01

    Solid-to-solid diffusion couples were assembled and annealed to examine the diffusion between pure Mg (99.96%) and Al (99.999%). Diffusion anneals were carried out at 300 , 350 , and 400 C for 720, 360, and 240 hours, respectively. Optical and scanning electron microscopes were utilized to identify the formation of the intermetallic phases, -Al12Mg17 and -Al3Mg2 and absence of the -phase in the diffusion couples. Thicknesses of the -Al12Mg17 and -Al3Mg2 phases were measured and the parabolic growth constants were calculated to determine the activation energies for the growth, 165 and 86 KJ/mole, respectively. Concentration profiles were determined with electron microprobe analysis using pure elemental standards. Composition-dependent interdiffusion coefficients in Mg-solid solution, -Al12Mg17 and - Al3Mg2 and Al-solid solutions were calculated based on the Boltzmann-Matano analysis. Average effective interdiffusion coefficients for each phase were also calculated, and the magnitude was the highest for the -Al3Mg2 phase, followed by -Al12Mg17, Al-solid solution and Mg-solid solution. Intrinsic diffusion coefficients based on Huemann s analysis (e.g., marker plane) were determined for the ~38 at.% Mg in the -Al3Mg2 phase. Activation energies and the pre-exponential factors for the inter- and intrinsic diffusion coefficients were calculated for the temperature range examined. The -Al3Mg2 phase was found to have the lowest activation energies for growth and interdiffusion among all four phases studied. At the marker location in the -Al3Mg2 phase, the intrinsic diffusion of Al was found to be faster than that of Mg. Extrapolations of the impurity diffusion coefficients in the terminal solid solutions were made and compared to the available self- and impurity diffusion data from literature. Thermodynamic factor, tracer diffusion coefficients and atomic mobilities at the marker plane composition were approximated using available literature values of Mg activity in the -Al3Mg2 phase.

  10. The role of boron in ductilizing Ni3Al

    NASA Technical Reports Server (NTRS)

    Vedula, K.; Shabel, B. S.; Khadkikar, P. S.

    1987-01-01

    Ductilization of Ni3Al at room temperature by microalloying with boron has been primarily attributed to the increased grain boundary cohesion in the presence of boron. However, another aspect of the role played by boron in ductilizing Ni3Al is revealed when the Hall-Petch relationships for Ni3Al and B-doped Ni3Al are compared. A shallower slope for the B-doped Ni3Al compared to that for Ni3Al indicates a reduced resistance to slip propagation across grain boundaries, and therefore reduced stress concentration at boundaries, in the presence of boron. This comparison of Hall-Petch relationships was carried out by generating data for powder processed B-doped Ni3Al at various grain sizes and by compiling data for Ni3Al from the literature. In addition, the room temperature fracture of B-doped Ni3Al has been shown to initiate along certain grain boundaries. The fracture eventually occurs by transgranular ductile tearing.

  11. Diamond/AlN Thin Films for Optical Applications

    SciTech Connect

    Knoebber, F.; Bludau, O.; Williams, O. A.; Sah, R. E.; Kirste, L.; Baeumler, M.; Nebel, C. E.; Ambacher, O.; Cimalla, V.; Lebedev, V.; Leopold, S.; Paetz, D.

    2010-11-01

    In this work we report on membranes made of nanocrystalline diamond (NCD) and AlN for the use in tunable micro-optics. For the growth of the AlN and NCD thin films, magnetron sputtering and chemical vapor deposition techniques have been used, respectively. A chemical-mechanical polishing process of NCD layers has been introduced, which is crucial for the growth of c-oriented, fiber textured AlN films. AlN layers deposited on as grown and polished nanocrystalline diamond along with free standing membranes have been compared by studying microstructure, surface morphology, piezoelectrical response as well as optical properties.

  12. Mathematik AG Wie verschickt man als Agent geheime

    E-print Network

    Steidl, Gabriele

    Mathematik AG Wie verschickt man als Agent geheime Botschaften? (Teil 2) #12;Kryptographie Krypto (=geheim) +graphein (=schreiben) Kryptographie (verschlüsseln) #12;Caesars geheime Botschaften Bereits

  13. Structure determination of Fe-Al-Ge alloys

    NASA Astrophysics Data System (ADS)

    Gargicevich, D.; Galván Josa, V. M.; Blanco, C.; Lambri, A.; Cuello, G. J.

    2015-11-01

    We studied the crystalline structure of Fe - 8at.%Al - 4at.%Ge alloy between 300 and 1300 K and its relation to the mechanical response by means of neutron diffraction and mechanical spectroscopy. At room temperature we observe a Fe3Al-type ordered structure with a deficiency of Al in the 8c sites. The Ge atoms are distributed in the 4a and Al atoms in 8c sites. At high temperature we observe an order-disorder transformation when the crystal structure becomes Fe-? type. This loss of order gives rise to the hysteresis behavior of damping between the heating and cooling runs.

  14. New Nb3Al conductor made by DRHQ process

    NASA Astrophysics Data System (ADS)

    Kikuchi, Akihiro; Iijima, Yasuo; Inoue, Kiyoshi; Kosuge, Michio

    2002-05-01

    Drastic improvements of superconducting properties, Tc, Hc2 and Jc have been obtained on the jelly roll Nb3Al multifilamentary wires through the DRHQ (double rapidly-heating/quenching) process. Tc and Hc2 (4.2 K) increased up to about 18.4 K and 30 T, values which are comparable with those of arc-melted stoichiometric Nb3Al. The DRHQ process can improve the superconducting performance of the Nb3Al wire without any 3rd element additions, and be applied directly to the jelly-roll Nb/Al precursor wires. Those impressive enhancements are caused by the phase transformation from Nb-Al supersaturated solid solutions into near-stoichiometric A15-Nb3Al at very high temperature about 1,900 °C. The TEM observations indicated that the DRHQ operation prevents the formation of stacking faults having Al-rich composition in the A15 superconducting grains. The winding process in the DRHQ operation may cause the wire breaking when including a lot of brittle A15 phase. However, the DRHQ process can be successfully applied by reducing bending strain on the Nb3Al wire with the Nb matrix/A15 ratio of 0.45, and resulting overall (non Cu) Jc (4.2 K) of DRHQ processed Nb3Al wire reaches 135 A/mm2 at 25 T.

  15. Electrical resistivity of Al-Cu liquid binary alloy

    NASA Astrophysics Data System (ADS)

    Thakor, P. P.; Patel, J. J.; Sonvane, Y. A.; Jani, A. R.

    2013-06-01

    Present paper deals with the electrical resistivity (?) of liquid Al-Cu binary alloy. To describe electron-ion interaction we have used our parameter free model potential along with Faber-Ziman formulation combined with Ashcroft-Langreth (AL) partial structure factor. To see the influence of exchange and correlation effect, Hartree, Taylor and Sarkar et al local field correlation functions are used. From present results, it is seen that good agreements between present results and experimental data have been achieved. Lastly we conclude that our model potential successfully produces the data of electrical resistivity (?) of liquid Al-Cu binary alloy.

  16. A screening assessment of cognitive impairment in patients with ALS.

    PubMed

    Gordon, Paul H; Wang, Yuanjia; Doorish, Carolyn; Lewis, Melissa; Battista, Vanessa; Mitsumoto, Hiroshi; Marder, Karen

    2007-12-01

    We wished to determine whether a screening test battery for cognitive impairment can be given practicably in a busy multidisciplinary ALS clinic, and to assess initial test performance in a sequentially drawn ALS population. We administered a word generation task (letter fluency), the Frontal Behavioral Inventory (FBI), and the Beck Depression Inventory (BDI) to 49 ALS patients and their caregivers during a visit to our ALS clinic. We also computed Clinical Dementia Rating (CDR) scale and ALS Functional Rating Scale (ALSFRS-R) scores for patients. Pearson correlation coefficients and regression analyses assessed associations between outcome measures. The test battery took 30 min to administer. Word generation was associated with the FBI score (r = -0.36, p = 0.01), and time to ALS diagnosis (p = 0.01). Caregiver depressive symptoms (BDI) correlated with the FBI (r = 0.40, p = 0.005) and motor severity (r = -0.47, p<0.01) in patients. CDR scores were associated with behavioral abnormalities and lower ALSFRS-R scores. We concluded that a screen of cognition could be administered during multidisciplinary ALS clinics. Frontostriatal cognitive impairment may be associated with behavioral syndromes and more rapid forms of ALS. Behavioral and motor impairment is associated with depressive symptoms in caregivers. Studies with formal neuropsychological tests are needed to determine the sensitivity and specificity of the screen in ALS. PMID:17852014

  17. Rapidly solidified Al-Ti alloys via advanced melt spinning

    SciTech Connect

    Jha, S.C.; Mozhi, T.A.; Ray, R. )

    1989-05-01

    Rapidly solidified Al-Ti based binary and ternary alloys containing 3 to 12 wt pct titanium and additions of cerium or vanadium have been produced by melt spinning continuous ribbons, pulverization into powders, and consolidation by hot-extrusion into round bars. The mechanical property data show that significantly improved elevated-temperature strengths can be obtained by suitable alloy design and processing. The rapidly solidified Al-Ti base alloys have improved general corrosion and pitting corrosion resistance in comparison to ingot metallurgy Al 7075-T73 alloys, and higher resistance to pitting corrosion than rapidly solidified Al-8Fe-2Mo. 10 refs.

  18. al-Qaida Strategy, Ideology, Doctrine, and Media

    ScienceCinema

    Dr. Jarret Brachman

    2010-09-01

    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.

  19. Isotopically exchangeable Al in coastal lowland acid sulfate soils.

    PubMed

    Yvanes-Giuliani, Yliane A M; Fink, D; Rose, J; Waite, T David; Collins, Richard N

    2016-01-15

    Periodic discharges of high concentrations of aluminium (Al) causing fish kills and other adverse effects occur worldwide in waterways affected by coastal lowland acid sulfate soils (CLASS). The exchangeability - a metal's ability to readily transfer between the soil solid- and solution-phases - of Al in these soils is therefore of particular importance as it has implications for metal transport, plant availability and toxicity to living organisms. In the present study, the concentrations of isotopically exchangeable Al (E values) were measured in 27 CLASS and compared with common salt extractions (i.e. KCl and CuCl2) used to estimate exchangeable soil pools of Al. E values of Al were high in the soils, ranging from 357 to 3040mg·kg(-1). Exchangeable concentrations estimated using 1M KCl were consistently lower than measured E values, although a reasonable correlation was obtained between the two values (E=1.68×AlKCl, r(2)=0.66, n=25). The addition of a 0.2M CuCl2 extraction step improved the 1:1 agreement between extractable and isotopically exchangeable Al concentrations, but lead to significant mobilisation of non-isotopically exchangeable Al in surficial 'organic-rich' CLASS having E values<1000mg·kg(-1). It was concluded that currently used (i.e. 1M KCl) methodology severely underestimates exchangeable Al and total actual acidity values in CLASS and should be corrected by a factor similar to the one determined here. PMID:26519574

  20. Ground-state electric quadrupole moment of 31Al

    E-print Network

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

    2008-10-16

    Ground-state electric quadrupole moment of 31Al (I =5/2+, T_1/2 = 644(25) ms) has been measured by means of the beta-NMR spectroscopy using a spin-polarized 31Al beam produced in the projectile fragmentation reaction. The obtained Q moment, |Q_exp(31Al)| = 112(32)emb, are in agreement with conventional shell model calculations within the sd valence space. Previous result on the magnetic moment also supports the validity of the sd model in this isotope, and thus it is concluded that 31Al is located outside of the island of inversion.

  1. Effect of calcination time on NiAl-Al2O3 using gel combustion synthesis method

    NASA Astrophysics Data System (ADS)

    Afandi, N. F.; Manap, A.; Yusof, S. N. A.; Salim, M. A.; Azim, M. Al.; Othman, S. Z.; Pauzi, N. I. M.; Omar, Nooririnah; Misran, H.

    2015-07-01

    This study was conducted in order to investigate the effect of calcination time on phase and microstructural characteristics of intermetallic matric composite (IMC), NiAl-Al2O3 powder. This powder was synthesized using gel combustion method with octyl alcohol as fuel. Upon completion of the combustion process, the loose powder was calcined at 1050°C for 1, 2 and 4 hours and characterized using XRD, FESEM and TEM. The crystallite size was calculated to be in the range of 29-30 nm. It was found that NiAl-Al2O3 exhibits high crystalline structure after calcination for 4 hours. Furthermore, longer calcination time also cause growth of the particle size. Findings indicate that high crystalline nanostructured NiAl-Al2O3 powder consisting of submicron particles can be successfully produced using gel combustion synthesis with longer calcination time.

  2. Synthesis and spectral investigation of Al(III) catechin/?-cyclodextrin and Al(III) quercetin/?-cyclodextrin inclusion compounds

    NASA Astrophysics Data System (ADS)

    Dias, Karina; Nikolaou, Sofia; De Giovani, Wagner F.

    2008-06-01

    Al-catechin/?-cyclodextrin and Al-quercetin/?-cyclodextrin (?-CD) inclusion compounds were synthesized and characterized by IR, UV-vis, 1H and 13C NMR and TG and DTA analyses. Because quercetin is sparingly soluble in water, the stability constants of the Al-quercetin/?-CD and Al-catechin/?-CD compounds were determined by phase solubility studies. The A L-type diagrams indicated the formation of 1:1 inclusion compounds and allowed calculation of the stability constants. The thermodynamic parameters were obtained from the dependence of the stability constants on temperature and results indicated that the formation of the inclusion compounds is an enthalpically driven process. The thermal decomposition of the solid Al-quercetin/?-CD and Al-catechin/?-CD inclusion compounds took place at different stages, compared with the respective precursors, proving that an inclusion complexation process really occurred.

  3. Microstructure Evolution of Cold-Sprayed Al-Si Alloy Coatings on ?-TiAl During Heat Treatment

    NASA Astrophysics Data System (ADS)

    Wang, Jiqiang; Kong, Lingyan; Li, Tiefan; Xiong, Tianying

    2015-08-01

    This paper investigated the influence of heat treatment on the microstructure of Al-Si alloy coatings on ?-TiAl alloy. The coatings were prepared by cold spraying with Al-12Si and Al-20Si alloy powders as the feedstock, and then the as-sprayed coatings were subjected to heat treatment. The microstructure, chemical composition, and phase transformation of the coatings were studied by SEM, XRD, and EPMA. The diffusing behavior of Al and Si during heat treatment was investigated. The results showed that a silicon-aluminizing coating was formed through the inward diffusion of Al/Si elements into the substrate. The obtained kinetics curve of the formation of silicon-aluminizing coating at 580 °C similarly followed parabolic law.

  4. Microstructure evolution during annealing of TiAl/NiCoCrAl multilayer composite prepared by EB-PVD

    SciTech Connect

    Zhang, Rubing; Zhang, Deming; Chen, Guiqing; Wang, Yuesheng

    2014-07-01

    TiAl/NiCoCrAl laminate composite sheet with a thickness of 0.4–0.6 mm as well as a dimension of 150 mm × 100 mm was fabricated successfully by using electron beam physical vapor deposition (EB-PVD) method. The annealing treatment was processed at 1123 and 1323 K for 3 h in a high vacuum atmosphere, respectively. The phase composition and microstructure of TiAl/NiCoCrAl microlaminated sheet have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Based on the sheet characterization and results of the microstructure evolution during annealing treatment process, the diffusion mechanism of interfacial reaction in TiAl/NiCoCrAl microlaminate was investigated and discussed.

  5. Tuning of the Land g-factor in Al 1-xAs/AlAs single and double quantum wells

    E-print Network

    Gusev, Guennady

    Tuning of the Landé g-factor in Al xGa 1-xAs/AlAs single and double quantum wells This article has Contact us My IOPscience #12;Tuning of the Land´e g-factor in AlxGa1-xAs/AlAs single and double quantum wells F. G. G. Hernandez1, G. M. Gusev1, and A. K. Bakarov2 1 Instituto de F´isica, Universidade de S

  6. The removal of bisphenol A from aqueous solutions by MIL-53(Al) and mesostructured MIL-53(Al).

    PubMed

    Zhou, Meimei; Wu, Yi-Nan; Qiao, Junlian; Zhang, Jing; McDonald, Amanda; Li, Guangtao; Li, Fengting

    2013-09-01

    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

  7. Increasing of AlGaAs/GaAs quantum well robustness to resonant excitation by lowering Al concentration in barriers

    NASA Astrophysics Data System (ADS)

    Solovev, I. A.; Davydov, V. G.; Kapitonov, Yu V.; Shapochkin, P. Yu; Efimov, Yu P.; Lovcjus, V. A.; Eliseev, S. A.; Petrov, V. V.; Ovsyankin, V. V.

    2015-11-01

    The robustness of AlGaAs/GaAs quantum well to strong resonant excitation is studied. It was found that lowering Al concentration in barriers to 3% does not influence the measured radiative linewidth of exciton resonance in the sample at low intensities. At the same time parasitic broadening of the resonance by an additional resonant illumination is strongly suppressed as compared to the quantum well with 30% of Al in barriers.

  8. Strain dependence on polarization properties of AlGaN and AlGaN-based ultraviolet lasers grown on AlN substrates

    SciTech Connect

    Bryan, Zachary Bryan, Isaac; Sitar, Zlatko; Collazo, Ramón; Mita, Seiji; Tweedie, James

    2015-06-08

    Since the band ordering in AlGaN has a profound effect on the performance of UVC light emitting diodes (LEDs) and even determines the feasibility of surface emitting lasers, the polarization properties of emitted light from c-oriented AlGaN and AlGaN-based laser structures were studied over the whole composition range, as well as various strain states, quantum confinements, and carrier densities. A quantitative relationship between the theoretical valence band separation, determined using k•p theory, and the experimentally measured degree of polarization is presented. Next to composition, strain was found to have the largest influence on the degree of polarization while all other factors were practically insignificant. The lowest crossover point from the transverse electric to transverse magnetic polarized emission of 245?nm was found for structures pseudomorphically grown on AlN substrates. This finding has significant implications toward the efficiency and feasibility of surface emitting devices below this wavelength.

  9. Advantages of deep-UV AlGaN light-emitting diodes with an AlGaN/AlGaN superlattices electron blocking layer

    NASA Astrophysics Data System (ADS)

    Yin, Yi An; Wang, Naiyin; Li, Shuti; Zhang, Yong; Fan, Guanghan

    2015-04-01

    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.

  10. Effect of Al-mole fraction in Al{sub x}Ga{sub 1?x}N grown by MOCVD

    SciTech Connect

    Jayasakthi, M. Ramesh, R. Prabakaran, K. Loganathan, R. Kuppulingam, B. Balaji, M. Arivazhagan, P. Sankaranarayanan, S. Singh, Shubra Baskar, K.

    2014-04-24

    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.

  11. Precipitation in cold-rolled Al–Sc–Zr and Al–Mn–Sc–Zr alloys prepared by powder metallurgy

    SciTech Connect

    Vlach, M.; Stulikova, I.; Smola, B.; Kekule, T.; Kudrnova, H.; Danis, S.; Gemma, R.; Ocenasek, V.; Malek, J.; Tanprayoon, D.; Neubert, V.

    2013-12-15

    The effects of cold-rolling on thermal, mechanical and electrical properties, microstructure and recrystallization behaviour of the AlScZr and AlMnScZr alloys prepared by powder metallurgy were studied. The powder was produced by atomising in argon with 1% oxygen and then consolidated by hot extrusion at 350 °C. The electrical resistometry and microhardness together with differential scanning calorimetry measurements were compared with microstructure development observed by transmission and scanning electron microscopy, X-ray diffraction and electron backscatter diffraction. Fine (sub)grain structure developed and fine coherent Al{sub 3}Sc and/or Al{sub 3}(Sc,Zr) particles precipitated during extrusion at 350 °C in the alloys studied. Additional precipitation of the Al{sub 3}Sc and/or Al{sub 3}(Sc,Zr) particles and/or their coarsening was slightly facilitated by the previous cold rolling. The presence of Sc,Zr-containing particles has a significant antirecrystallization effect that prevents recrystallization at temperatures minimally up to 420 °C. The precipitation of the Al{sub 6}Mn- and/or Al{sub 6}(Mn,Fe) particles of a size ? 1.0 ?m at subgrain boundaries has also an essential antirecrystallization effect and totally suppresses recrystallization during 32 h long annealing at 550 °C. The texture development of the alloys seems to be affected by high solid solution strengthening by Mn. The precipitation of the Mn-containing alloy is highly enhanced by a cold rolling. The apparent activation energy of the Al{sub 3}Sc particles formation and/or coarsening and that of the Al{sub 6}Mn and/or Al{sub 6}(Mn,Fe) particle precipitation in the powder and in the compacted alloys were determined. The cold deformation has no effect on the apparent activation energy values of the Al{sub 3}Sc-phase and the Al{sub 6}Mn-phase precipitation. - Highlights: • The Mn, Sc and Zr additions to Al totally suppresses recrystallization at 550 °C. • The Sc,Zr-containing particle precipitation is slightly facilitated by cold rolling. • The Mn-containing particle precipitation is highly enhanced by cold rolling. • Cold rolling has no effect on activation energy of the Al{sub 3}Sc and Al{sub 6}Mn precipitation. • The texture development is affected by high solid solution strengthening by Mn.

  12. Experimental determination of the top of the valence band in amorphous Al2O3 and ?-Al2O3

    NASA Astrophysics Data System (ADS)

    Konyushenko, M. A.; Filatova, E. O.; Konashuk, A. S.; Nelyubov, A. V.; Shulakov, A. S.

    2015-10-01

    Abstract—Investigation of the energy distribution of occupied states in the valence band and determination of its upper level in films of amorphous Al2O3 and ?-Al2O3, synthesized by atomic layer deposition on a silicon substrate, was performed by X-ray photoelectron spectroscopy. The top of the valence gap in ?-Al2O3 was found to shift by 0.8 eV towards larger electron binding energies with respect to amorphous Al2O3.

  13. Ultrafast Bulk Diffusion of AlHxin High-Entropy Dehydrogenation Intermediates of NaAlH4

    SciTech Connect

    Zhang, Feng; Wood, Brandon C; Wang, Yan; Wang, Cai-Zhuang; Ho, Kai-Ming; Chou, Mei-Yin

    2014-08-14

    Using first-principles molecular dynamics (FPMD) and total-energy calculations, we demonstrate low-barrier bulk diffusion of Al-bearing species in ?-NaAlH4, a recently proposed high-entropy polymorph of NaAlH4. For charged AlH4– and neutral AlH3 vacancies, the computed barriers for diffusion are <0.1 eV, and we directly observe the predicted diffusive pathways in FPMD simulations at picosecond time scales. In contrast, such diffusion in the ? phase is inaccessible to FPMD, consistent with much higher barriers. The transport behavior of ?-NaAlH4, in addition to key dynamical and structural signatures, is consistent with experimental observations of high-mobility species, strongly supporting the idea that an intermediate transition from the ? phase to a high-entropy polymorph facilitates the hydrogen-releasing decomposition of NaAlH4. Our results provide an answer to longstanding questions regarding the responsible agent for the experimentally observed efficient Al transport during dehydrogenation and suggest that mass transport and phase transformation kinetics are coupled. Implications for understanding the (de)hydrogenation of undoped and catalyzed NaAlH4 are discussed.

  14. Characterization of Dendritic Microstructure, Intermetallic Phases, and Hardness of Directionally Solidified Al-Mg and Al-Mg-Si Alloys

    NASA Astrophysics Data System (ADS)

    Brito, Crystopher; Costa, Thiago A.; Vida, Talita A.; Bertelli, Felipe; Cheung, Noé; Spinelli, José Eduardo; Garcia, Amauri

    2015-08-01

    Despite the widespread application of Al-Mg-Si alloys, especially in the automotive industry, interrelations of solidification thermal parameters (cooling rate and growth rate), microstructure, and hardness are not properly established. For instance, the control of the scale of the microstructure on both Al-Mg and Al-Mg-Si alloys by adequate pre-programming of the solidification thermal parameters remains a task to be accomplished. In the present study, the directional solidification (DS) of these alloys under unsteady-state solidification conditions is investigated in an attempt to characterize the evolution of microstructural features, macrosegregation, and hardness as a function of local solidification thermal parameters along the DS castings length. Silicon addition to the Al-Mg alloy was found not to affect the sizes of primary and secondary dendrite arm spacings, but induced the onset of tertiary dendritic branches and affected also the size and distribution of intermetallic particles within the interdendritic regions. The Al-Mg-Si alloy is characterized by a more complex arrangement of phases, including binary ( ?-Al + Mg2Si) and refined ternary ( ?-Al + Mg2Si + AlFe(Si) eutectic mixtures. As a consequence, a higher Vickers hardness profile is shown to be associated with the ternary Al-Mg-Si alloy DS casting. For both alloys examined, hardness is shown to increase with the increase in the microstructural spacing according to Hall-Petch type equations.

  15. Oxidation Resistant Ti-Al-Fe Diffusion Barrier for FeCrAlY Coatings on Titanium Aluminides

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    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.

  16. Laser irradiation of ZnO:Al/Ag/ZnO:Al multilayers for electrical isolation in thin film photovoltaics

    PubMed Central

    2013-01-01

    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

  17. 75 FR 2920 - In the Matter of the Designation of al-Qa'ida in the Arabian Peninsula (AQAP), Also Known as al...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-19

    ...al-Qa'ida in the Arabian Peninsula (AQAP), Also Known as al-Qa'ida of Jihad...Organization in the Arabian Peninsula (AQAP), Also Known as al-Qa'ida in Yemen...al-Qa'ida in the Arabian Peninsula (AQAP), and also known as al-Qa'ida...

  18. 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

    2012-12-11

    ...DEPARTMENT OF STATE [Public Notice 8105] In the Matter of the Amendment of the Designation of al-Qa'ida in Iraq, aka Jam'at al Tawhid wa'al-Jihad, aka The Monotheism and Jihad Group, aka The al-Zarqawi Network, aka al-Tawhid, aka...

  19. 77 FR 4083 - Amendment of the Designation of al-Qa'ida in Iraq, et al. as a Specially Designated Global...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-26

    ...Terrorist Entity Pursuant to Executive Order 13224 In the Matter of the Amendment of the Designation of al-Qa'ida in Iraq, aka Jam'at al Tawhid wa'al-Jihad, aka The Monotheism and Jihad Group, aka The al-Zarqawi Network, aka al-Tawhid, aka...

  20. 77 FR 4082 - Review and Amendment of the Designation of al-Qa'ida in Iraq, et al. as a Foreign Terrorist...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-26

    ...the Immigration and Nationality Act In the Matter of the Review and Amendment of the Designation of al-Qa'ida in Iraq, aka Jam'at al Tawhid wa'al-Jihad, aka The Monotheism and Jihad Group, aka The al-Zarqawi Network, aka al- Tawhid, aka...

  1. 75 FR 76771 - In the Matter of the Designation of Fahd Mohammed Ahmed al-Quso, also known as Fahd al-Quso, also...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-09

    ... Matter of the Designation of Fahd Mohammed Ahmed al-Quso, also known as Fahd al-Quso, also known as Abu...-Bara', also known as Abu Hathayfah al-Adani, also known as Fahd Mohammed Ahmed al-Awlaqi, also known as... January 23, 2003, I hereby determine that the individual known as Fahd Mohammed Ahmed al-Quso, also...

  2. SEmantic portAL --The SEAL approach Alexander Maedche,

    E-print Network

    Staab, Steffen

    SEmantic portAL -- The SEAL approach ½ ¿ Alexander Maedche, ½ ¾ Steffen Staab, ½ Nenad Stojanovic developed a generic approach for developing semantic portals, viz. SEAL (SEmantic portAL), that exploits querying [6] or dynamic hypertext views [29]. Thus, ontologies constitute the foundation of our SEAL

  3. SEAL --a SEmantic portAL with content management functionality

    E-print Network

    Staab, Steffen

    SEAL -- a SEmantic portAL with content management functionality Steffen Staab1,2 , Rudi Studer1Web portal, viz. SEAL (SEmantic portAL). In particular, we describe some of the core challenges that SEAL must meet. Because of the distributed nature of research information, SEAL has been developed

  4. Intermetallic compound formation at Cu-Al wire bond interface

    NASA Astrophysics Data System (ADS)

    Bae, In-Tae; Young Jung, Dae; Chen, William T.; Du, Yong

    2012-12-01

    Intermetallic compound (IMC) formation and evolution at Cu-Al wire bond interface were studied using focused ion beam /scanning electron microscopy, transmission electron microscopy (TEM)/energy dispersive x-ray spectroscopy (EDS), nano beam electron diffraction (NBED) and structure factor (SF) calculation. It was found that discrete IMC patches were formed at the Cu/Al interface in as-packaged state and they grew toward Al pad after high temperature storage (HTS) environment at 150 °C. TEM/EDS and NBED results combined with SF calculation revealed the evidence of metastable ?'-CuAl2 IMC phase (tetragonal, space group: I4¯m2, a = 0.404 nm, c = 0.580 nm) formed at Cu/Al interfaces in both of the as-packaged and the post-HTS samples. Two feasible mechanisms for the formation of the metastable ?'-CuAl2 phase are discussed based on (1) non-equilibrium cooling of wire bond that is attributed to highly short bonding process time and (2) the epitaxial relationships between Cu and ?'-CuAl2, which can minimize lattice mismatch for ?'-CuAl2 to grow on Cu.

  5. The structure of 23Al and astrophysical consequences 

    E-print Network

    Zhai, Yongjun

    2009-05-15

    Motivated by existing nuclear astrophysics problems, the B-decay of the proton rich nucleus 23Al was studied for the first time with pure samples which were obtained by using the 1H(24Mg,23Al)2n reaction and the MARS recoil separator at Texas A&M...

  6. Plagiarism in Linguistic Editing Dr. Ismael Al-Qayam

    E-print Network

    Plagiarism in Linguistic Editing Abstract Dr. Ismael Al-Qayam Philadelphia University This paper deals with the phenomena of plagiarism in linguistic editing in modern times. The paper does not limit Lughawiyya is plagiarized from a number of former linguists, especially Mohammed Al Adnani and Mohammed Dhari

  7. Gaseous modification of MCrAlY coatings

    DOEpatents

    Vance, Steven J. (Orlando, FL); Goedjen, John G. (Oviedo, FL); Sabol, Stephen M. (Orlando, FL); Sloan, Kelly M. (Longwood, FL)

    2000-01-01

    The present invention generally describes methods for modifying MCrAlY coatings by using gaseous carburization, gaseous nitriding or gaseous carbonitriding. The modified MCrAlY coatings are useful in thermal barrier coating systems, which may be used in gas turbine engines.

  8. 78 FR 39023 - ING Investments, LLC, et al.;

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-28

    ... From the Federal Register Online via the Government Printing Office SECURITIES AND EXCHANGE COMMISSION ING Investments, LLC, et al.; Notice of Application June 24, 2013. AGENCY: Securities and Exchange... shareholder approval. \\1\\ Portfolio Partners, Inc., et al., Investment Company Act Release Nos. 25558 (Apr....

  9. Assessing the Incremental Algorithm: A Response to Krahmer et al.

    ERIC Educational Resources Information Center

    van Deemter, Kees; Gatt, Albert; van der Sluis, Ielka; Power, Richard

    2012-01-01

    This response discusses the experiment reported in Krahmer et al.'s Letter to the Editor of "Cognitive Science". We observe that their results do not tell us whether the Incremental Algorithm is better or worse than its competitors, and we speculate about implications for reference in complex domains, and for learning from "normal" (i.e.,…

  10. 77 FR 57026 - Drawbridge Operation Regulation; Black Warrior River, AL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-17

    ... SECURITY Coast Guard 33 CFR Part 117 RIN 1625-AA09 Drawbridge Operation Regulation; Black Warrior River, AL... Black Warrior River, mile 219.0, at Demopolis, AL. The bridge is operated automatically and currently... of Homeland Security FR Federal Register NPRM Notice of Proposed Rulemaking Sec. Section Symbol...

  11. Oxidation behavior of FeAl+Hf,Zr,B

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Doychak, Joseph

    1988-01-01

    The oxidation behavior of Fe-40Al-1Hf, Fe-40Al-1Hf-0.4B, and Fe-40Al-0.1Zr-0.4B (at. percent) alloys was characterized after 900, 1000, and 100 C exposures. Isothermal tests revealed parabolic kinetics after a period of transitional theta-alumina scale growth. The parabolic growth rates for the subsequent alpha-alumina scales were about five times higher than those for NiAl+0.1Zr alloys. The isothermally grown scales showed a propensity toward massive scale spallation due to both extensive rumpling from growth stresses and to an inner layer of HfO2. Cyclic oxidation for 200 1-hr cycles produced little degradation at 900 or 1000 C, but caused significant spallation at 1100 C in the form of small segments of the outer scale. The major difference in the cyclic oxidation of the three FeAl alloys was increased initial spallation for FeAl+Zr,B. Although these FeAl alloys showed many similarities to NiAl alloys, they were generally less oxidation resistant. It is believed that this resulted from nonoptimal levels of dopants and larger thermal expansion mismatch stresses.

  12. Irradiation-enhanced reactivity of multilayer Al/Ni nanomaterials.

    PubMed

    Manukyan, Khachatur V; Tan, Wanpeng; deBoer, Richard J; Stech, Edward J; Aprahamian, Ani; Wiescher, Michael; Rouvimov, Sergei; Overdeep, Kyle R; Shuck, Christopher E; Weihs, Timothy P; Mukasyan, Alexander S

    2015-06-01

    We have investigated the effect of accelerated ion beam irradiation on the structure and reactivity of multilayer sputter deposited Al/Ni nanomaterials. Carbon and aluminum ion beams with different charge states and intensities were used to irradiate the multilayer materials. The conditions for the irradiation-assisted self-ignition of the reactive materials and corresponding ignition thresholds for the beam intensities were determined. We discovered that relatively short (40 min or less) ion irradiations enhance the reactivity of the Al/Ni nanomaterials, that is, significantly decrease the thermal ignition temperatures (Tig) and ignition delay times (?ig). We also show that irradiation leads to atomic mixing at the Al/Ni interfaces with the formation of an amorphous interlayer, in addition to the nucleation of small (2-3 nm) Al3Ni crystals within the amorphous regions. The amorphous interlayer is thought to enhance the reactivity of the multilayer energetic nanomaterial by increasing the heat of the reaction and by speeding the intermixing of the Ni and the Al. The small Al3Ni crystals may also enhance reactivity by facilitating the growth of this Al-Ni intermetallic phase. In contrast, longer irradiations decrease reactivity with higher ignition temperatures and longer ignition delay times. Such changes are also associated with growth of the Al3Ni intermetallic and decreases in the heat of reaction. Drawing on this data set, we suggest that ion irradiation can be used to fine-tune the structure and reactivity of energetic nanomaterials. PMID:25915560

  13. Aluminum sulfate (alum; Al2 O) is used as a

    E-print Network

    Sparks, Donald L.

    477 Aluminum sulfate (alum; Al2 (SO4 )3 ·14H2 O) is used as a chemical treatment of poultry litter, and pelletizing, the use of chemical amendments, primarily aluminum sulfate (alum, Al2 (SO4 )3 ·14H2 O), alter

  14. On Al-26 and other short-lived interstellar radioactivity

    NASA Technical Reports Server (NTRS)

    Clayton, Donald D.; Hartmann, Dieter H.; Leising, Mark D.

    1993-01-01

    Several authors have shown that massive stars exploding at a rate of about three per century can account for a large portion, if not all, of the observed interstellar Al-26. In a separate argument using models of Galactic chemical evolution, Clayton (1984) showed that the Al-26/Al-27 production ratio was not large enough to maintain enough Al-26 in the Galactic disk gas of about 10 exp 10 solar masses having solar composition. We present a resolution of those conflicting arguments. A past history of Galactic infall growing the Galactic disk so dilutes the stable Al-27 concentration that the two approaches can be brought into near agreement. If massive stars dominate the production of Al-26, we suggest that the apparent shortfall of their Al-26/Al-27 yield ratio is to be interpreted as evidence for significant growth of the Galactic disk. We also discuss the implications of these arguments for other extinct radioactivities in meteorites, using I-129 and Sm-146 as examples.

  15. Screening for cognitive impairment in a Chinese ALS population.

    PubMed

    Wei, Qianqian; Chen, Xueping; Zheng, Zhenzhen; Huang, Rui; Guo, Xiaoyan; Cao, Bei; Bak, Thomas H; Shang, Huifang

    2015-03-01

    Despite growing interest in cognitive impairment of ALS patients, there are only limited studies available that characterize cognitive deficits in the Chinese ALS population through highly sensitive and specific screening tools. The Chinese version of the Addenbrooke's Cognitive Examination-revised (ACE-R) and mini-mental state examination (MMSE) were applied to evaluate cognitive function in 145 sporadic ALS patients and 50 healthy controls. The mean onset age was 50.72 ± 12.38 years. Results showed that the prevalence of cognitive deficits was 14.48% and 30.34% based on the MMSE and ACE-R, respectively. Patients had a broad range of cognitive impairment domains, including language (26.21%), orientation/attention (24.13%), visuospatial ability (24.13%), memory (23.45%) and verbal fluency (22.76%). Logistic regression indicated that older age of onset, female gender and lower educational levels were potential determinants of cognitive deficits in ALS. Multiple regression analyses showed that the cognitive deficit during the baseline visit was not associated with the progression rate of ALS. In conclusion, cognitive impairment is common in Chinese ALS patients, but does not necessarily worsen the progression of ALS. ACE-R is superior to MMSE in detecting deficits in patients. Cognitive impairment in ALS patients may relate to age of onset, female gender and lower education level. PMID:25309978

  16. Perrodin et al. Voice cells in the primate temporal lobe

    E-print Network

    Temporal Lobe. Current Biology 21, 1408-1415 (2011)). 1 #12;Perrodin et al. Summary Communication signals selective representations of communication signals. 2 #12;Perrodin et al. Highlights - FMRI, such as voice category. - Voice cells show a sparse coding strategy that has not been seen for face cells

  17. Lanthanide Al-Ni base Ericsson cycle magnetic refrigerants

    DOEpatents

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

    1995-10-31

    A magnetic refrigerant for a magnetic refrigerator using the Ericsson thermodynamic cycle comprises DyAlNi and (Gd.sub.0.54 Er.sub.0.46)AlNi alloys having a relatively constant .DELTA.Tmc over a wide temperature range.

  18. Lanthanide Al-Ni base Ericsson cycle magnetic refrigerants

    DOEpatents

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

    1995-10-31

    A magnetic refrigerant for a magnetic refrigerator using the Ericsson thermodynamic cycle comprises DyAlNi and (Gd{sub 0.54}Er{sub 0.46})AlNi alloys having a relatively constant {Delta}Tmc over a wide temperature range. 16 figs.

  19. Simultaneous incorporation of Mn and Al in the goethite structure

    NASA Astrophysics Data System (ADS)

    Alvarez, Mariana; Rueda, Elsa H.; Sileo, Elsa E.

    2007-02-01

    Two series of (Al,Mn)-substituted goethites were synthesized from ferrihydrite made in alkaline media, with different Al/Mn mole ratios ([Al + Mn]/Fe molar ratio up to 0.12). Powder X-ray diffraction and extended X-ray absorption fine structure (EXAFS) techniques were used to assess the structural characteristics of the simultaneous substitution in goethite. XRD patterns revealed that all the obtained solids remain in a goethite-like structure. Rietveld refinement of X-ray diffraction data indicates that the increasing Mn substitution and consequent decrease of Al substitution causes an increase in the unit cell volume. This change is accompanied by the increment of the various Me-Me distances. XANES spectra at the Al and Mn K-edge confirm the octahedral coordination of Al and the trivalent oxidation state of the Mn ion in all the synthesized samples. EXAFS spectra at the Fe K-edge indicate that the local order around the Fe atom remains practically constant upon (Mn,Al) substitution. Measurements in the Mn K-edge show that distances Mn-Me suffer different changes with the increase in Mn substitution: a marked decrease in E and a slight decrease in E', while DC remains constant. E and E' values correspond to the distance between one Mn and one neighboring Me (Fe, Mn, Al) atom, both situated in two polyhedra linked by an edge. These polyhedra belong to the same double row of the goethite structure. DC value corresponds to the distance between one Mn and one Me (Fe, Mn, Al) atom, situated in two octahedral linked by one corner and belonging to two adjacent double chains. All the intermetallic distances are minor than the corresponding singly substituted goethites, this fact is attributed to the structure contraction due to the presence of Al(III) which restrains the axial distortion of Mn. Dissolution-time curves, resulting from exposure to 6 M HCl at 318 K, show that the dissolution rate slows with increasing Al substitution and consequent decrease of Mn substitution, and the shape of the curve becomes increasingly sigmoidal for mixed goethite with large Al content and Al-goethite. Dissolution kinetics of most samples are well described by the Kabai equation. Al dissolves almost congruently with respect to Fe, implying that it is homogeneously distributed in the structure. However, the convex ?Mn: ?Fe curve indicates that Mn tends to be concentrated in the outer layers of the goethite particles.

  20. Al/SiOx/Al single and multiband metamaterial absorbers for terahertz sensor applications

    NASA Astrophysics Data System (ADS)

    Kearney, Brian; Alves, Fabio; Grbovic, Dragoslav; Karunasiri, Gamani

    2013-01-01

    To increase the sensitivity of uncooled thermal sensors in the terahertz (THz) spectral range (1 to 10 THz), we investigated thin metamaterial layers exhibiting resonant absorption in this region. These metamaterial films are comprised of periodic arrays of aluminum (Al) squares and an Al ground plane separated by a thin silicon-rich silicon oxide (SiOx) dielectric film. These standard MEMS materials are also suitable for fabrication of bi-material and microbolometer thermal sensors. Using SiOx instead of SiO2 reduced the residual stress of the metamaterial film. Finite element simulations were performed to establish the design criteria for very thin films with high absorption and spectral tunability. Single-band structures with varying SiOx thicknesses, square size, and periodicity were fabricated and found to absorb nearly 100% at the designed frequencies between three and eight THz. Multiband absorbing structures were fabricated with two or three distinct peaks or a single-broad absorption band. Experimental results indicate that is possible to design very efficient thin THz absorbing films to match specific applications.

  1. Marinobacter hydrocarbonoclasticus Gauthier et al. 1992 and Marinobacter aquaeolei Nguyen et al. 1999 are heterotypic synonyms.

    PubMed

    Márquez, M C; Ventosa, A

    2005-05-01

    The genus Marinobacter was described with a single species, Marinobacter hydrocarbonoclasticus Gauthier et al. 1992, to place a hydrocarbon-degrading marine bacterium belonging to the gamma-subclass of the Proteobacteria. Marinobacter aquaeolei Nguyen et al. 1999, the second described species of the genus, was proposed for a strain isolated from an oil-producing well on an offshore platform in southern Vietnam, on the basis of differences in the whole-cell protein pattern and lipopolysaccharide composition, although its phenotypic and genotypic characteristics were very similar to those of the type species, M. hydrocarbonoclasticus. In the present paper, literature data concerning the two species were reviewed. Fatty acid composition, G+C content and DNA-DNA hybridization studies were performed in order to clarify the taxonomic positions of these two species. Based on the results obtained in this study and phenotypic and phylogenetic traits available from the literature, it is proposed that the two species should be united under the same name; according to the rules of priority, M. hydrocarbonoclasticus, the first described species, is the earlier synonym and M. aquaeolei is the later synonym. PMID:15879281

  2. Melting Behavior of Al/Pb/Sn/Al Multilayered Thin Films

    NASA Astrophysics Data System (ADS)

    Khan, Patan Yousaf; Devi, M. Manolata; Biswas, Krishanu

    2015-09-01

    Metals or alloy nanoparticles (NPs) have been reported to exhibit superheating on melting when coated with higher melting point material or embedded in a matrix. This is due to the suppression of the heterogeneous nucleation of the melt at the epitaxial interface. For 2D thin films, this necessary condition is not feasible because even if a thin film is sandwiched between higher melting temperature materials with coherent interfaces, the heterogeneous nucleation of melt is possible at various detects. However, it has earlier been reported that 2D thin films of the pure metal sandwiched by other materials can exhibit superheating by suppression of melt growth. In order to probe this effect in case of alloy thin films, the present investigation has been carried out on Pb/Sn multilayers sandwiched between Al layers. The present study shows that such sandwiched thin films prepared by accumulative roll bonding process cause the formation of biphasic NPs in the intermixed region of Pb and Sn. Al layers undergo severe plastic deformation, leading to the generation of dislocations and sub-grain boundaries. DSC (differential canning calorimeter) thermograms of the films indicate superheating of 3 K to 6 K (or 3 °C to 6 °C). Theoretical analysis using currently available literatures has been carried out to justify the finding in the present investigation.

  3. Global transcriptome analysis of Al-induced genes in an Al-accumulating species, common buckwheat (Fagopyrum esculentum Moench).

    PubMed

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

    2014-12-01

    Buckwheat (Fagopyrum esculentum Moench) is a species with high aluminum (Al) tolerance and accumulation. Although the physiological mechanisms for external and internal detoxification of Al have been well studied, the molecular mechanisms responsible are poorly understood. Here, we conducted a genome-wide transcriptome analysis of Al-responsive genes in the roots and leaves using RNA sequencing (RNA-Seq) technology. RNA-Seq generated reads ranging from 56×10(6) to 93×10(6). A total of 148,734 transcript contigs with an average length of 1,014 bp were assembled, generating 84,516 unigenes. Among them, 31,730 and 23,853 unigenes were annotated, respectively, in the NCBI plant database and TAIR database for Arabidopsis. Of the annotated genes, 4,067 genes in the roots and 2,663 genes in the leaves were up-regulated (>2-fold) by Al exposure, while 2,456 genes in the roots and 2,426 genes in the leaves were down-regulated (<2-fold) A few STOP1/ART1 (SENSITIVE TO PROTON RHIZOTOXICITY1/AL RESISTANCE TRANSCRIPTION FACTOR1)-regulated gene homologs including FeSTAR1, FeALS3 (ALUMINUM SENSITIVE3), FeALS1 (ALUMINUM SENSITIVE1), FeMATE1 and FeMATE2 (MULTIDRUG AND TOXIC COMPOUND EXTRUSION1 and 2) were also up-regulated in buckwheat, indicating some common Al tolerance mechanism across the species, although most STOP1/ART1-regulated gene homologs were not changed. Most genes involved in citric and oxalic acid biosynthesis were not significantly altered. Some transporter genes were highly expressed in the roots and leaves and responded to Al stress, implicating their role in Al tolerance and accumulation. Overall, our data provide a platform for further characterizing the functions of genes involved in Al tolerance and accumulation in buckwheat. PMID:25273892

  4. Luminescence properties of wurtzite AlN nanotips

    NASA Astrophysics Data System (ADS)

    Shi, Shih-Chen; Chen, Chia Fu; Chattopadhyay, Surojit; Chen, Kuei-Hsien; Ke, Bo-Wen; Chen, Li-Chyong; Trinkler, Laima; Berzina, Baiba

    2006-10-01

    The optical properties of aluminum nitride nanotips (AlNNTs) synthesized via vapor transport and condensation process have been studied by cathodoluminescence, photoluminescence (PL), thermoluminescence (TL), and UV absorption measurements. Two defect related transitions around 2.1 and 3.4eV and an excitonic feature at 6.2eV were identified. Compared to the AlN macropowders, the AlNNTs showed a blueshift (+0.2eV) of the ˜3.2eV peak. Analysis of both PL and TL excitation measurements indicated the existence of subband gap multiple energy levels in AlNNTs. A significant TL intensity even at 145°C suggests possible ultraviolet detector and dosimetric applications of these AlNNTs.

  5. Stability and electronic structure of AlN nanotubes

    NASA Astrophysics Data System (ADS)

    Zhao, Mingwen; Xia, Yueyuan; Zhang, Dongju; Mei, Liangmo

    2003-12-01

    We predict the stability and electronic structure of aluminum nitride nanotubes based on calculations using density functional theory. The lower strain energy required in order to wrap up an AlN graphitic sheet into a tube and good thermal stability indicate the possibility for the formation of AlN nanotubes. All the AlN nanotubes are semiconductors with band gaps ranging from 2.84 to 3.95 eV. The zigzag nanotube is a semiconductor with a direct band gap, whereas the armchair nanotube has an indirect band gap. Contrary to the cases of carbon nanotubes, the band gap of AlN nanotubes increases with the increasing diameter of the tubes and saturates at a value corresponding to the calculated band gap of an AlN hexagonal sheet.

  6. De novo mutations in ataxin-2 gene and ALS risk.

    PubMed

    Laffita-Mesa, José Miguel; Rodríguez Pupo, Jorge Michel; Moreno Sera, Raciel; Vázquez Mojena, Yaimee; Kourí, Vivian; Laguna-Salvia, Leonides; Martínez-Godales, Michael; Valdevila Figueira, José A; Bauer, Peter O; Rodríguez-Labrada, Roberto; González Zaldívar, Yanetza; Paucar, Martin; Svenningsson, Per; Velázquez Pérez, Luís

    2013-01-01

    Pathogenic CAG repeat expansion in the ataxin-2 gene (ATXN2) is the genetic cause of spinocerebellar ataxia type 2 (SCA2). Recently, it has been associated with Parkinsonism and increased genetic risk for amyotrophic lateral sclerosis (ALS). Here we report the association of de novo mutations in ATXN2 with autosomal dominant ALS. These findings support our previous conjectures based on population studies on the role of large normal ATXN2 alleles as the source for new mutations being involved in neurodegenerative pathologies associated with CAG expansions. The de novo mutations expanded from ALS/SCA2 non-risk alleles as proven by meta-analysis method. The ALS risk was associated with SCA2 alleles as well as with intermediate CAG lengths in the ATXN2. Higher risk for ALS was associated with pathogenic CAG repeat as revealed by meta-analysis. PMID:23936447

  7. High temperature dispersion strengthening of NiAl

    NASA Technical Reports Server (NTRS)

    Sherman, M.; Vedula, K.

    1986-01-01

    A potential high temperature strengthening mechanism for alloys based on the intermetallic compound NiAl was investigated. This study forms part of an overall program at NASA Lewis Research Center for exploring the potential of alloys based on NiAl for high temperature applications. An alloy containing 2.26 at% Nb and produced by hot extrusion of blended powders was examined in detail using optical and electron microscopy. Interdiffusion between the blended Nb and NiAl powders results in the formation of intermediate phases. A fine dispersion of precipitates of a hexagonal, ordered NiAlNb phases in a matrix of NiAl can be produced and this results in strengthening of the alloy by interfering with dislocation motion at high temperature. These precipitates are, however, found to coarsen during the high temperature (1300 K) deformation at slow strain rates and this may impose some limitatioins on the use of this strengthening mechanism.

  8. Physical and mechanical metallurgy of NiAl

    NASA Technical Reports Server (NTRS)

    Noebe, Ronald D.; Bowman, Randy R.; Nathal, Michael V.

    1994-01-01

    Considerable research has been performed on NiAl over the last decade, with an exponential increase in effort occurring over the last few years. This is due to interest in this material for electronic, catalytic, coating and especially high-temperature structural applications. This report uses this wealth of new information to develop a complete description of the properties and processing of NiAl and NiAl-based materials. Emphasis is placed on the controlling fracture and deformation mechanisms of single and polycrystalline NiAl and its alloys over the entire range of temperatures for which data are available. Creep, fatigue, and environmental resistance of this material are discussed. In addition, issues surrounding alloy design, development of NiAl-based composites, and materials processing are addressed.

  9. Structure and properties of nanocomposite Nb-Al-N films

    NASA Astrophysics Data System (ADS)

    Ivashchenko, V. I.; Pogrebnjak, A. D.; Sobol', O. V.; Skrynskii, P. L.; Rogoz, V. N.; Meilekhov, A. A.; Dub, S. N.; Kupchishin, A. I.

    2015-08-01

    Nanocomposite Nb-Al-N films prepared by magnetron sputtering have been studied. It has been found that, in the films, there are two stable crystalline structural states, namely, NbN z and B1-Nb1 - x Al x N y O1 - y , and an amorphous-like component related to aluminum oxynitride upon reactive magnetron sputtering. It has been established that the substructure characteristics are sensitive to the current supplied to an Al target and are related to the Knoop nanohardness and hardness, which change in the ranges of 29-33.5 and 46-48 GPa, respectively. Ab initio calculations for the NbN z and Nb2AlN phases and NbN/AlN heterostructures have been performed to interpret the obtained results for the first time.

  10. Electrical Transport Properties of Liquid Al-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Thakore, B. Y.; Khambholja, S. G.; Suthar, P. H.; Jani, A. R.

    2010-06-01

    Electrical transport properties viz. electrical resistivity, thermoelectric power and thermal conductivity of liquid Al-Cu alloys as a function of Cu concentration have been studied in the present paper. Ashcroft empty core model potential has been used to incorporate the ion-electron interaction. To incorporate the exchange and correlation effects, five different forms of local field correction functions viz. Hartree, Taylor, Ichimaru et al., Farid et al. and Sarkar et al. have been used. The transport properties of binary system have been studied using Faber-Ziman formulation combined with Ashcroft-Langreth (AL) partial structure factor. The computed values of electrical resistivity are compared with experimental data and for low Cu concentration, good agreement has been observed. Further, thermoelectric power and thermal conductivity have also been predicted.

  11. Dynamics of Agglutinin-Like Sequence (ALS) Protein Localization on the Surface of Candida Albicans

    ERIC Educational Resources Information Center

    Coleman, David Andrew

    2009-01-01

    The ALS gene family encodes large cell-surface glycoproteins associated with "C. albicans" pathogenesis. Als proteins are thought to act as adhesin molecules binding to host tissues. Wide variation in expression levels among the ALS genes exists and is related to cell morphology and environmental conditions. "ALS1," "ALS3," and "ALS4" are three of…

  12. Interaction of Al with O2 exposed Mo2BC

    NASA Astrophysics Data System (ADS)

    Bolvardi, Hamid; Music, Denis; Schneider, Jochen M.

    2015-03-01

    A Mo2BC(0 4 0) surface was exposed to O2. The gas interaction was investigated using ab initio molecular dynamics and X-ray photoelectron spectroscopy (XPS) of air exposed surfaces. The calculations suggest that the most dominating physical mechanism is dissociative O2 adsorption whereby Mosbnd O, Osbnd Mosbnd O and Mo2sbnd Csbnd O bond formation is observed. To validate these results, Mo2BC thin films were synthesized utilizing high power pulsed magnetron sputtering and air exposed surfaces were probed by XPS. MoO2 and MoO3 bond formation is observed and is consistent with here obtained ab initio data. Additionally, the interfacial interactions of O2 exposed Mo2BC(0 4 0) surface with an Al nonamer is studied with ab initio molecular dynamics to describe on the atomic scale the interaction between this surface and Al to mimic the interface present during cold forming processes of Al based alloys. The Al nonamer was disrupted and Al forms chemical bonds with oxygen contained in the O2 exposed Mo2BC(0 4 0) surface. Based on the comparison of here calculated adsorption energy with literature data, Alsbnd Al bonds are shown to be significantly weaker than the Alsbnd O bonds formed across the interface. Hence, Alsbnd Al bond rupture is expected for a mechanically loaded interface. Therefore the adhesion of a residual Al on the native oxide layer is predicted. This is consistent with experimental observations. The data presented here may also be relevant for other oxygen containing surfaces in a contact with Al or Al based alloys for example during forming operations.

  13. Smart oxygen diffusion barrier based on IrAl alloy

    SciTech Connect

    Hosoda, Hideki; Watanabe, Sadao; Hanada, Shuji

    1999-07-01

    Ir should be used as an effective oxygen diffusion barrier (ODB) for ultrahigh temperature structural materials since Ir exhibits extremely low oxygen diffusivity. Oxidation resistance of Ir is, however, not good due to formation of gaseous oxide, IrO{sub 3}, over 1,390K. In this study, the improvement of oxidation resistance was aimed through alloy design of alloying with Al. IrAl is expected to form a self-healing multifunctional layered structure composed of Ir layer as ODB and Al{sub 2}O{sub 2} layer as a protective oxide (PO) on the Ir layer. Ar arc-melted IrAl alloy was crushed into powder, followed by hot pressing and heat treatment to remove Ir formed by eutectic reaction. Oxidation behavior was measured using thermogravimetry (TG) and differential thermal analysis (DTA) under the conditions of (1) dynamic heating of 0.167K/s and (2) isotherms at 1,273K to 1,673K in O{sub 2} environment. It was found that oxidation resistance is much improved by alloying with Al and that the designed structure (PO/ODB) is formed on the IrAl substrate. Compressive mechanical properties were investigated from RT to 1873K: both the strength as a function of normalized temperature and specific strength are higher than those of pure Ir, NiAl, TiAl and Ni{sub 3}Al. IrAl is promising as an advanced smart coating material equipping good oxidation resistance as well as high temperature strength.

  14. Microstructural and mechanical characterization of Al–Zn–Si nanocomposites

    SciTech Connect

    García-Villarreal, S.; Chávez-Valdez, A.; Moreno, K.J.; Leyva, C.; Aguilar-Martínez, J.A.; Hurtado, A.; Arizmendi-Morquecho, A.

    2013-09-15

    In this paper the addition of silicon nanoparticles into Al–Zn alloys to form metallic matrix nanocomposites by mechanical alloying process was investigated. The influence of various process parameters such as milling time and Si concentration in the Al–Zn matrix has an interesting effect on the microstructure and mechanical properties of the synthesized nanocomposites. The microstructural characterization of the nanocomposites was evaluated by transmission electron microscopy and energy dispersive X-ray spectroscopy (TEM–EDXS) and the mechanical properties were measured by nanoindentation and micro-hardness tests. The results showed that during mechanical milling Si is added to the Al–Zn matrix achieving a uniform and homogeneous dispersion. After solidification, it forms small particles of AlZnSi with blocky morphology in interdendritic regions. The nanoindentation profiles showed that the elastic modulus and hardness properties increase with increasing milling time. However, a high concentration of Si (> 1.2 wt.%) results in a saturation of Si in the Al–Zn matrix, which adversely affects the mechanical properties. Thus, it is important to tune the milling time and concentration of Si added to the Al–Zn alloys to control the growth of brittle phases that result in reduction of the mechanical properties of the material. - Highlights: • A novel technique for addition of Si nanocomposites into Al–Zn liquid alloy is reported. • Good dispersion and homogeneity of Si in the Al–Zn matrix are obtained. • Increasing Si content above 1.2 wt.% decreases the mechanical properties of Al–Zn alloy. • The saturation point of Si in 1.2 wt.% differs from Galvalume® composition. • The Al–Zn–1.5Si alloy with addition of nanocomposite shows 5.7 GPa of hardness.

  15. Microbial Bioreactor Development in the ALS NSCORT

    NASA Astrophysics Data System (ADS)

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

    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 the development of efficient microbial bioreactors for treatment of human, crop, and food-process wastes while enabling resource recovery. The approach emphasizes optimizing the energy-saving advantages of hydrolytic enzymes for biomass degradation, with focus on treatment of solid wastes including crop residue, paper, food, and human metabolic wastes, treatment of greywater, cabin air, off-gases from other treatment systems, and habitat condensate. This summary includes important findings from those projects, status of technology development, and recommendations for next steps. The Plant-based Anaerobic-Aerobic Bioreactor-Linked Operation (PAABLO) system was developed to reduce crop residue while generating energy and/or food. Plant residues initially were added directly to the bioreactor, and recalcitrant residue was used as a substrate for growing plants or mushrooms. Subsequently, crop residue was first pretreated with fungi to hydrolyze polymers recalcitrant to bacteria, and leachate from the fungal beds was directed to the anaerobic digester. Exoenzymes from the fungi pre-soften fibrous plant materials, improving recovery of materials that are more easily biodegraded to methane that can be used for energy reclamation. An Autothermal Thermophilic Aerobic Digestion (ATAD) system was developed for biodegradable solid wastes. Objectives were to increase water and nutrient recovery, reduce waste volume, and inactivate pathogens. Operational parameters of the reactor were optimized for degradation and resource recovery while minimizing system requirements and footprint. The start-up behavior and recycling of effluent supernatant were evaluated to maximize degradation and minimize water input. The off-gases proceeded to a bioregenerative air-treatment reactor, and the sludge effluent was investigated for multiple downstream uses including dewatering by reed beds, use as a nutrient supplement for fish or mushroom growth, and as a growth medium and nutrient source for various crops. The Bio-Regenerative Environmental Air Treatment for Health (BREATHe I) reactor treated greywater and off-gases from the thermophilic aerobic digestion reactor which contained elevated levels of ammonia (NH3 ) and hydrogen sulfide (H2 S). BREATHe I development focused initially on removing greywater contaminants with clean air supplied to a biotrickling filter. Limited removal of organic carbon (70%) led to studies indicating that biodegradation metabolites of the surfactant disodium cocoamphodiacetate are recalcitrant. Subsequent studies showed that NH3 loaded at 150 mg/min and H2 S at 0.83 mg/min were removed completely, while removal of carbonaceous compounds from greywater remained constant. A BREATHe II reactor emphasized biofilters and biotrickling filters for removal of ersatz multicomponent gaseous waste streams representative of habitat air and atmospheric condensate. The model waste stream contained a mixture of acetone, n-butanol, methane, ethylene, and ammonia. Both biofilters and biotrickling filters packed with different media were able to achieve complete removal of easily soluble compounds such as acetone, n-butanol, and ammonia within a short startup period, whereas methane was not removed because of its extreme aqueous insolubility. Different packing media and bioreactor configurations were subsequently assessed, as well as the effect of influent ammonia concentration. Research sponsored in part by NASA grant NAG5-12686.

  16. Effect of Physical Properties of Al-Si Electrode Films on the Deformation Behaviors and the Strength of Thick Al Wire Bonds during Thermal Cycle Test

    NASA Astrophysics Data System (ADS)

    Shimizu, Yousuke; Tomota, Yo; Onuki, Jin; Khoo, Khyou Pin; Kurosu, Toshiki

    2009-06-01

    The deformation behaviors of Al-Si films and the strength change of Al wire bonds on Al-Si films during heating and cooling cycles have been investigated as a function of substrate temperature of the sputtering process; the purpose was to clarify reliability of both Al wire bonds and Al-Si films for use in insulated gate bipolar transistor (IGBT) modules. The extent of deformation in Al-Si films sputtered at 593 K during heating and cooling cycles was the smallest among films sputtered at room temperature (RT), 473 K, and 593 K. The strength of Al wire bonds on Al-Si films sputtered at the three temperatures was the highest for Al-Si films sputtered at 593 K. The reliability of Al wire bonds on Al-Si films formed at 593 K was about two times higher than the bond reliability on Al-Si films formed at RT and 473 K.

  17. 75 FR 26316 - In the Matter of the Designation of Qasim al-Rimi, Also Known as Qasim Yahya Mahda `abd al-Rimi...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-11

    ...-Remi, Also Known as Qasim al-Rami, Also Known as Abu Harayrah, Also Known as Abu Hurayrah al-San'ai...-Raymi, also known as Qasim al-Rami, also known as Abu Harayrah, also known as Abu Hurayrah...

  18. Unraveling the Origin of Structural Disorder in High Temperature Transition Al2O3: Structure of ?-Al2O3

    SciTech Connect

    Kovarik, Libor; Bowden, Mark E.; Shi, Dachuan; Washton, Nancy M.; Anderson, Amity; Hu, Jian Z.; Lee, Jaekyoung; Szanyi, Janos; Kwak, Ja Hun; Peden, Charles HF

    2015-09-22

    The crystallography of transition Al2O3 has been extensively studied in the past due to the advantageous properties of the oxide in catalytic and a range of other technological applications. However, existing crystallographic models are insufficient to describe the structure of many important Al2O3 polymorphs due to their highly disordered nature. In this work, we investigate structure and disorder in high-temperature treated transition Al2O3, and provide a structural description for ?-Al2O3 by using a suite of complementary imaging, spectroscopy and quantum calculation techniques. Contrary to current understanding, our high-resolution imaging shows that ?-Al2O3 is a disordered composite phase of at least two different end members. By correlating imaging and spectroscopy results with DFT calculations, we propose a model that describes ?-Al2O3 as a disordered intergrowth of two crystallographic variants at the unit cell level. One variant is based on ?-Ga2O3, and the other on a monoclinic phase that is closely-related to ?-Al2O3. The overall findings and interpretations afford new insight into the origin of poor crystallinity in transition Al2O3, and also provide new perspectives on structural complexity that can emerge from intergrowth of closely related structural polymorphs.

  19. Table S1. Biome classification used in this study and its relationship to Reichenbacher et al.'s (1998) classification.

    E-print Network

    Hurlbert, Allen

    1998-01-01

    .'s (1998) classification. Biomesused in thisstudy Reichenbacher et al.'s(1998) biomes Arctic/Taiga Polar (High Arctic) Tundra Arctic/Taiga Alaskan Tundra Arctic/Taiga Canadian (Low Arctic) Tundra Arctic/Taiga Alaskan-Alpine Tundra Arctic/Taiga Alaska-Yukon Subarctic Conifer Conifer Forest Arctic/Taiga Canadian

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

    E-print Network

    Neuhauser, Barbara

    wafer process J. P. Castlea,b, M. F. Cunninghama,b, B. Neuhausera,b, S. Golwalab, F. P. Lipschultza at Storrs We have developed a "full wafer" process for producing Al/Al2O3/Cu superconductor and stable, and junctions produced on the same wafer had very similar tunneling characteristics. However

  1. Cryptanalysis of Cho et al.'s Protocol, A HashBased Mutual Authentication Protocol for RFID Systems

    E-print Network

    International Association for Cryptologic Research (IACR)

    Cryptanalysis of Cho et al.'s Protocol, A Hash­Based Mutual Authentication Protocol for RFID. In this paper we cryptanalysis a hash based RFID mutual authentication protocol which has been recently proposed. Keywords: RFID, Authentication, Desynchronization Attack, Tag Impersonation Attack, Reader Impersonation

  2. Environmental Risk Factors and Amyotrophic Lateral Sclerosis (ALS): A Case-Control Study of ALS in Michigan

    PubMed Central

    Yu, Yu; Su, Feng-Chiao; Callaghan, Brian C.; Goutman, Stephen A.; Batterman, Stuart A.; Feldman, Eva L.

    2014-01-01

    An interim report of a case-control study was conducted to explore the role of environmental factors in the development of amyotrophic lateral sclerosis (ALS). Sixty-six cases and 66 age- and gender-matched controls were recruited. Detailed information regarding residence history, occupational history, smoking, physical activity, and other factors was obtained using questionnaires. The association of ALS with potential risk factors, including smoking, physical activity and chemical exposure, was investigated using conditional logistic regression models. As compared to controls, a greater number of our randomly selected ALS patients reported exposure to fertilizers to treat private yards and gardens and occupational exposure to pesticides in the last 30 years than our randomly selected control cases. Smoking, occupational exposures to metals, dust/fibers/fumes/gas and radiation, and physical activity were not associated with ALS when comparing the randomly selected ALS patients to the control subjects. To further explore and confirm results, exposures over several time frames, including 0–10 and 10–30 years earlier, were considered, and analyses were stratified by age and gender. Pesticide and fertilizer exposure were both significantly associated with ALS in the randomly selected ALS patients. While study results need to be interpreted cautiously given the small sample size and the lack of direct exposure measures, these results suggest that environmental and particularly residential exposure factors warrant close attention in studies examining risk factors of ALS. PMID:24979055

  3. The in vitro biocompatibility and macrophage phagocytosis of Mg17Al12 phase in Mg-Al-Zn alloys.

    PubMed

    Liu, Chen; He, Peng; Wan, Peng; Li, Mei; Wang, Kehong; Tan, Lili; Zhang, Yu; Yang, Ke

    2015-07-01

    Mg alloys are gaining interest for applications as biodegradable medical implant, including Mg-Al-Zn series alloys with good combination of mechanical properties and reasonable corrosion resistance. However, whether the existence of second phase particles in the alloys exerts influence on the biocompatibility is still not clear. A deeper understanding of how the particles regulate specific biological responses is becoming a crucial requirement for their subsequent biomedical application. In this work, the in vitro biocompatibility of Mg17Al12 as a common second phase in biodegradable Mg-Al-Zn alloys was investigated via hemolysis, cytotoxicity, cell proliferation, and cell adhesion tests. Moreover, osteogenic differentiation was evaluated by the extracellular matrix mineralization assay. The Mg17Al12 particles were also prepared to simulate the real situation of second phase in the in vivo environment in order to estimate the cellular response in macrophages to the Mg17Al12 particles. The experimental results indicated that no hemolysis was found and an excellent cytocompatibility was also proved for the Mg17Al12 second phase when co-cultured with L929 cells, MC3T3-E1 cells and BMSCs. Macrophage phagocytosis co-culture test revealed that Mg17Al12 particles exerted no harmful effect on RAW264.7 macrophages and could be phagocytized by the RAW264.7 cells. Furthermore, the possible inflammatory reaction and metabolic way for Mg17Al12 phase were also discussed in detail. PMID:25424541

  4. Influence of impact speed on water droplet erosion of TiAl compared with Ti6Al4V

    PubMed Central

    Mahdipoor, M.S.; Kirols, H.S.; Kevorkov, D.; Jedrzejowski, P.; Medraj, M.

    2015-01-01

    Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER?~?Vn, where the speed exponent is 7–9 for Ti6Al4V and 11–13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603??m. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl. PMID:26391370

  5. Early View (EV): 1-EV et al. 2012, Thibaud et al. 2014). The principle is to simu-

    E-print Network

    regarding new techniques, protocols or evaluation methods (Elith et al. 2006, 2010, Phillips et al. 2009, UMR 7208), Muséum national d'Histoire naturelle, Univ. Pierre et Marie Curie, Univ. de Caen Basse, and Virginia Inst. of Marine Science, College of William and Mary, PO Box 1346, Gloucester Point, VA 23062, USA

  6. Effect of Cu Addition to Zn-12Al Alloy on Thermal Properties and Wettability on Cu and Al Substrates

    NASA Astrophysics Data System (ADS)

    Gancarz, Tomasz; Pstru?, Janusz; Mosi?ska, Sylwia; Pawlak, Sylwia

    2015-11-01

    The thermal properties, electrical resistivity, thermal linear expansion and tensile strength of a new high-temperature lead-free solder based on a eutectic Zn-Al alloy with 0.5, 1.0, or 1.5 at. pct Cu added were studied. Wettability studies on Cu substrate were performed with flux at 773 K (500 °C) for 60, 180, 240, 900, 1800, and 3600 seconds, and for 480 seconds at 733 K, 753 K, 773 K, 793 K, and 823 K (460 °C, 480 °C, 500 °C, 520 °C, and 550 °C, respectively). The experiment was designed to demonstrate the effect of the addition of Cu on the kinetics of the formation and growth of the CuZn, Cu5Zn8, CuZn4, and Al4Cu9 phases, which were identified by X-ray diffraction analysis. Wetting tests were also performed on the Al substrate, for 15 and 30 seconds at 773 K and 793 K (500 °C and 520 °C, respectively). Very low contact angles on Al pads were obtained. The electrical resistivity of Zn-Al-Cu alloys was slightly higher than that of the ZnAl eutectic alloy. The present results are discussed with respect to the available literature on Zn-Al and Zn-Al-Cu alloys.

  7. Formation of a Novel Ordered Ni3Al Surface Structure by Codeposition on NiAl(110)

    E-print Network

    Han, Yong

    The formation of a new type of ordered 2D Ni3Al overlayer by low-temperature codeposition on NiAl(110) is demonstrated by kinetic Monte Carlo simulation of a multisite atomistic lattice-gas model with a precise treatment ...

  8. Influence of impact speed on water droplet erosion of TiAl compared with Ti6Al4V

    NASA Astrophysics Data System (ADS)

    Mahdipoor, M. S.; Kirols, H. S.; Kevorkov, D.; Jedrzejowski, P.; Medraj, M.

    2015-09-01

    Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER?~?Vn, where the speed exponent is 7-9 for Ti6Al4V and 11-13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603??m. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl.

  9. Microstructure of Reaction Zone Formed During Diffusion Bonding of TiAl with Ni/Al Multilayer

    NASA Astrophysics Data System (ADS)

    Simões, Sónia; Viana, Filomena; Koçak, Mustafa; Ramos, A. Sofia; Vieira, M. Teresa; Vieira, Manuel F.

    2012-05-01

    In this article, the characterization of the interfacial structure of diffusion bonding a TiAl alloy is presented. The joining surfaces were modified by Ni/Al reactive multilayer deposition as an alternative approach to conventional diffusion bonding. TiAl substrates were coated with alternated Ni and Al nanolayers. The nanolayers were deposited by dc magnetron sputtering with 14 nm of period (bilayer thickness). Joining experiments were performed at 900 °C for 30 and 60 min with a pressure of 5 MPa. Cross sections of the joints were prepared for characterization of their interfaces by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), high resolution TEM (HRTEM), energy dispersive x-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Several intermetallic compounds form at the interface, assuring the bonding of the TiAl. The interface can be divided into three distinct zones: zone 1 exhibits elongated nanograins, very small equiaxed grains are observed in zone 2, while zone 3 has larger equiaxed grains. EBSD analysis reveals that zone 1 corresponds to the intermetallic Al2NiTi and AlNiTi, and zones 2 and 3 to NiAl.

  10. Influence of impact speed on water droplet erosion of TiAl compared with Ti6Al4V.

    PubMed

    Mahdipoor, M S; Kirols, H S; Kevorkov, D; Jedrzejowski, P; Medraj, M

    2015-01-01

    Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER ~ V(n), where the speed exponent is 7-9 for Ti6Al4V and 11-13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603 ?m. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl. PMID:26391370

  11. 77 FR 51048 - United States et al. v. Verizon Communications Inc. et al.; Proposed Final Judgment and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-23

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF JUSTICE Antitrust Division United States et al. v. Verizon Communications Inc. et al.; Proposed Final Judgment and Competitive Impact Statement Notice is hereby given pursuant to the Antitrust Procedures and Penalties Act, 15 U.S.C. 16(b)-(h), that a...

  12. USC CHEM 322aL Summer 2015 JUNG/MOORE1 CHEMISTRY 322aL ORGANIC CHEMISTRY

    E-print Network

    Rohs, Remo

    USC CHEM 322aL Summer 2015 JUNG/MOORE1 CHEMISTRY 322aL ORGANIC CHEMISTRY COURSE SYLLABUS SUMMER is available at the USC Bookstore or directly from the publisher. LECTURE "Organic Chemistry" M. Loudon, 5th Ed. "Study Guide and Solutions Manual to Accompany Organic Chemistry" Loudon and Stowell, 5th Ed. "Molecular

  13. Stimulated emission and optical gain in AlGaN heterostructures grown on bulk AlN substrates

    SciTech Connect

    Guo, Wei Bryan, Zachary; Kirste, Ronny; Bryan, Isaac; Hussey, Lindsay; Bobea, Milena; Haidet, Brian; Collazo, Ramón; Sitar, Zlatko; Xie, Jinqiao; Mita, Seiji; Gerhold, Michael

    2014-03-14

    Optical gain spectra for ?250?nm stimulated emission were compared in three different AlGaN-based structures grown on single crystalline AlN substrates: a single AlGaN film, a double heterostructure (DH), and a Multiple Quantum Well (MQW) structure; respective threshold pumping power densities of 700, 250, and 150?kW/cm{sup 2} were observed. Above threshold, the emission was transverse-electric polarized and as narrow as 1.8?nm without a cavity. The DH and MQW structures showed gain values of 50–60?cm{sup ?1} when pumped at 1?MW/cm{sup 2}. The results demonstrated the excellent optical quality of the AlGaN-based heterostructures grown on AlN substrates and their potential for realizing electrically pumped sub-280?nm laser diodes.

  14. AlN passivation layer-mediated improvement in tensile failure of flexible ZnO:Al thin films.

    PubMed

    Choi, Hong Rak; Mohanty, Bhaskar Chandra; Kim, Jong Seong; Cho, Yong Soo

    2010-09-01

    AlN passivation layer-mediated improvement in tensile failure of ZnO:Al thin films on polyethersulfone substrates is investigated. ZnO:Al films without any passivation layer were brittle with a crack-initiating bending strain ?c of only about 1.13% with a saturated crack density ?s of 0.10 ?m(-1) and a fracture energy ? of 49.6 J m(-2). On passivation by an AlN overlayer, the fracture energy of the system increased considerably and a corresponding improvement in ?c was observed. AlN layers deposited at higher discharge powers yielded higher fracture energy and exhibited better performance in terms of ?c and ?s. PMID:20718429

  15. Cryptanalysis and improvement of Yan et al.'s biometric-based authentication scheme for telecare medicine information systems.

    PubMed

    Mishra, Dheerendra; Mukhopadhyay, Sourav; Chaturvedi, Ankita; Kumari, Saru; Khan, Muhammad Khurram

    2014-06-01

    Remote user authentication is desirable for a Telecare Medicine Information System (TMIS) for the safety, security and integrity of transmitted data over the public channel. In 2013, Tan presented a biometric based remote user authentication scheme and claimed that his scheme is secure. Recently, Yan et al. demonstrated some drawbacks in Tan's scheme and proposed an improved scheme to erase the drawbacks of Tan's scheme. We analyze Yan et al.'s scheme and identify that their scheme is vulnerable to off-line password guessing attack, and does not protect anonymity. Moreover, in their scheme, login and password change phases are inefficient to identify the correctness of input where inefficiency in password change phase can cause denial of service attack. Further, we design an improved scheme for TMIS with the aim to eliminate the drawbacks of Yan et al.'s scheme. PMID:24880932

  16. Theoretical analysis of compatibility of several reinforcement materials with NiAl and FeAl matrices

    NASA Technical Reports Server (NTRS)

    Misra, Ajay K.

    1989-01-01

    Several potential reinforcement materials were assessed for their chemical, coefficient of thermal expansion (CTE), and mechanical compatibility with the intermetallic matrices based on NiAl and FeAl. Among the ceramic reinforcement materials, Al2O3, TiC, and TiB2, appear to be the optimum choices for NiAl and FeAl matrices. However, the problem of CTE mismatch with the matrix needs to be solved for these three reinforcement materials. Beryllium-rich intermetallic compounds can be considered as potential reinforcement materials provided suitable reaction barrier coatings can be developed for these. Based on preliminary thermodynamic calculations, Sc2O3 and TiC appear to be suitable as reaction barrier coatings for the beryllides. Several reaction barrier coatings are also suggested for the currently available SiC fibers.

  17. Influence of Al grain boundaries segregations and La-doping on embrittlement of intermetallic NiAl

    NASA Astrophysics Data System (ADS)

    Kovalev, Anatoly I.; Wainstein, Dmitry L.; Rashkovskiy, Alexander Yu.

    2015-11-01

    The microscopic nature of intergranular fracture of NiAl was experimentally investigated by the set of electron spectroscopy techniques. The paper demonstrates that embrittlement of NiAl intermetallic compound is caused by ordering of atomic structure that leads to formation of structural aluminum segregations at grain boundaries (GB). Such segregations contain high number of brittle covalent interatomic bonds. The alloying by La increases the ductility of material avoiding Al GB enrichment and disordering GB atomic structure. The influence of La alloying on NiAl mechanical properties was investigated. GB chemical composition, atomic and electronic structure transformations after La doping were investigated by AES, XPS and EELFS techniques. To qualify the interatomic bonds metallicity the Fermi level (EF) position and electrons density (neff) in conduction band were determined in both undoped and doped NiAl. Basing on experimental results the physical model of GB brittleness formation was proposed.

  18. Confinement of surface acoustic waves in AlN /GaN/?-LiAlO2 acoustic wells

    NASA Astrophysics Data System (ADS)

    Takagaki, Y.; Chilla, E.; Ploog, K. H.

    2005-02-01

    We numerically investigate the characteristics of surface acoustic waves (SAWs) in AlN /GaN/?-LiAlO2 heterostructures. The markedly large sound velocity in AlN in comparison to that in GaN leads to an expulsion of SAWs from the top AlN layer and their resultant relocation to the middle GaN layer in the short-wavelength regime. The SAW velocity in the limit of zero wavelength is given by a bulk sound velocity of GaN, owing to the capping by the AlN barrier layer. The extra confinement of the SAW power in the acoustic well is advantageous in manipulating the operation of GaN-based devices by SAWs. The threshold velocity for the appearance of guided Rayleigh-like modes is found to be smaller than the bulk transverse sound velocity in the substrate. The present system exhibits furthermore unusual bowing behavior in the SAW dispersion.

  19. In situ microscopy of rapidly heated nano-Al and nano-Al/WO{sub 3} thermites

    SciTech Connect

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

    2010-09-27

    The initiation and reaction mechanism of nano-Al and nano-Al thermites in rapid heating environments is investigated in this work. A semiconductor-based grid/stage was used, capable of in situ heating of a sample from room temperature to 1473 K, and at a rate of 10{sup 6} K/s, inside an electron microscope. Nano-Al was rapidly heated in a transmission electron microscope, and before and after images indicate that the aluminum migrates through the shell, consistent with a diffusion-based mechanism. A nano-Al/WO{sub 3} composite was then heated in a scanning electron microscope. The results indicate that a reactive sintering mechanism is occurring for the nano-Al/WO{sub 3} thermite, as the products are found to be in surface contact and significantly deformed after the heating pulse.

  20. Dopant-free GaN/AlN/AlGaN radial nanowire heterostructures as high electron mobility transistors.

    PubMed

    Li, Yat; Xiang, Jie; Qian, Fang; Gradecak, Silvija; Wu, Yue; Yan, Hao; Blom, Douglas A; Lieber, Charles M

    2006-07-01

    We report the rational synthesis of dopant-free GaN/AlN/AlGaN radial nanowire heterostructures and their implementation as high electron mobility transistors (HEMTs). The radial nanowire heterostructures were prepared by sequential shell growth immediately following nanowire elongation using metal-organic chemical vapor deposition (MOCVD). Transmission electron microscopy (TEM) studies reveal that the GaN/AlN/AlGaN radial nanowire heterostructures are dislocation-free single crystals. In addition, the thicknesses and compositions of the individual AlN and AlGaN shells were unambiguously identified using cross-sectional high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM). Transport measurements carried out on GaN/AlN/AlGaN and GaN nanowires prepared using similar conditions demonstrate the existence of electron gas in the undoped GaN/AlN/AlGaN nanowire heterostructures and also yield an intrinsic electron mobility of 3100 cm(2)/Vs and 21,000 cm(2)/Vs at room temperature and 5 K, respectively, for the heterostructure. Field-effect transistors fabricated with ZrO(2) dielectrics and metal top gates showed excellent gate coupling with near ideal subthreshold slopes of 68 mV/dec, an on/off current ratio of 10(7), and scaled on-current and transconductance values of 500 mA/mm and 420 mS/mm. The ability to control synthetically the electronic properties of nanowires using band structure design in III-nitride radial nanowire heterostructures opens up new opportunities for nanoelectronics and provides a new platform to study the physics of low-dimensional electron gases. PMID:16834431

  1. Effect of Al{sub 2}Ti phase on plastic behavior in Ti-62.5 at% Al single crystals

    SciTech Connect

    Nakano, Takayoshi; Hayashi, Koutarou; Ashida, Keishi; Umakoshi, Yukichi

    1999-07-01

    The microstructure and plastic deformation behavior in Ti-62.5at.%Al single crystals were investigated focusing on effect of the formation of h- and r-Al{sub 2}Ti precipitates. Crystal structure, morphology and volume fraction of the precipitates depended strongly on the annealing temperature. The r-Al{sub 2}Ti phase precipitated as a plate in the L1{sub 0} matrix containing Al{sub 5}Ti{sub 3} superstructure below 1,200 C, while the h-Al{sub 2}Ti phase appeared at the higher temperature. The r-Al{sub 2}Ti had six-fold periodicity along the c-axis of the L1{sub 0} structure and formed a semi-coherent boundary with the matrix maintaining an orientation relationship with ({l{underscore}brace}101){sub r-Al2Ti}//({l{underscore}brace}101){sub L10}. In contrast, small particles of h-Al{sub 2}Ti with three-fold periodicity along the b-axis were homogeneously distributed in the matrix forming an obscure coherent phase boundary. Yield stress for specimens with a [201] loading axis anomaly increased showing a maximum peak around 800 C and then rapidly decreased. {l{underscore}brace}111{r{underscore}brace}[{l{underscore}angle}110] slip was dominant in the L1{sub 0} matrix and r-Al{sub 2}Ti precipitates at temperatures below the peak, while slip occurred on (001) above the peak temperature. The anomalous strengthening and the change in operative slip system were discussed focusing on the effect of anisotropy of APB energy and formation of Al{sub 2}Ti precipitates.

  2. ?-MnAl with high coercivity and saturation magnetization

    NASA Astrophysics Data System (ADS)

    Wei, J. Z.; Song, Z. G.; Yang, Y. B.; Liu, S. Q.; Du, H. L.; Han, J. Z.; Zhou, D.; Wang, C. S.; Yang, Y. C.; Franz, A.; Többens, D.; Yang, J. B.

    2014-12-01

    In this paper, high purity ?-Mn54Al46 and Mn54-xAl46Cxalloys were successfully prepared using conventional arc-melting, melt-spinning, and heat treatment process. The magnetic and the structural properties were examined using x-ray diffraction (XRD), powder neutron diffraction and magnetic measurements. A room temperature saturation magnetization of 650.5 kAm-1, coercivity of 0.5 T, and a maximum energy product of (BH)max = 24.7 kJm-3 were achieved for the pure Mn54Al46 powders without carbon doping. The carbon substituted Mn54-xAl46Cx, however, reveals a lower Curie temperature but similar saturation magnetization as compared to the carbon-free sample. The electronic structure of MnAl shows that the Mn atom possesses a magnetic moment of 2.454 ?B which results from strong hybridization between Mn-Al and Mn-Mn. We also investigated the volume and c/a ratio dependence of the magnetic moments of Mn and Al. The results indicate that an increase in the intra-atomic exchange splitting due to the cell volume expansion, leads to a large magnetic moment for the Mn atom. The Mn magnetic moment can reach a value of 2.9 ?B at a volume expansion rate of ?V/V ? 20%.

  3. Methotrexate intercalated ZnAl-layered double hydroxide

    SciTech Connect

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-15

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 A in pristine LDH to 21.3 A in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion. - Graphical abstract: ZnAl-layered double hydroxide intercalated with methotrexate ({approx}34% loading) promises the possibility of use of ZnAl-LDH material as drug carrier and in controlled delivery. Highlights: > ZnAl-layered double hydroxide methotrexate nanohybrid has been synthesized. > XRD and TEM studies on nanohybrid revealed successful intercalation of methotrexate. > TG and CHN analyses showed {approx}34 wt% of methotrexate loading into the nanohybrid. > Possibility of use of ZnAl-LDH material as drug carrier and in delivery.

  4. Natural history and therapy of AL cardiac amyloidosis.

    PubMed

    Grogan, Martha; Dispenzieri, Angela

    2015-03-01

    The natural history of immunoglobulin light chain associated amyloidosis (AL) is determined by the extent of cardiac involvement. Patients with cardiac AL and symptomatic heart failure have a median survival of approximately six months without successful treatment of the underlying plasma cell disorder The outcome in cardiac AL is determined by both the severity of cardiac involvement and the response to treatment. Staging systems using cardiac biomarkers, including NT- proBNP and troponin, have been found to be powerful predictors of prognosis and are used to guide treatment. Arrhythmias are common in cardiac AL and may lead to acute hemodynamic compromise. Sudden cardiac death, often due to pulseless electrical activity, is an important cause of early mortality. Supportive therapy for heart failure is usually limited to diuretics. Beta-blockers, ACE-inhibitors, and angiotensin receptor blockers are poorly tolerated in cardiac AL and should be avoided. Cardiac transplantation is controversial and reserved for highly selected patients with limited extracardiac involvement. The primary target of treatment in cardiac AL is obliteration of the plasma cell clone, using chemotherapy alone or combined with autologous stem cell transplantation. Despite the risk of early mortality, overall survival has improved with advances in disease modifying therapy. Earlier diagnosis and treatment of cardiac AL is crucial to improving survival. PMID:25447844

  5. Phase Transformations in Nb-Al-Ti alloys

    NASA Astrophysics Data System (ADS)

    Menon, E. S. K.; Subramanian, P. R.; Dimiduk, D. M.

    1996-06-01

    Phase relationships as well as morphological and crystallographic features in Nb-rich Nb-Al and Nb-Al-Ti alloys have been investigated. The phase boundaries involving the bcc and Nb3Al (A15 structure) were experimentally determined and several isothermal sections of the Nb-rich corner of the Nb-AI-Ti phase diagram established. The present findings show that (a) the solubility of Al in Nb is considerably less than that reported previously, (b) the high-temperature bcc phase undergoes an ordering transformation to the B2 structure, and (c) the ? phase also forms in these alloys. The sequence of decomposition of the high-temperature bcc phase during isothermal decomposition in the bcc + Nb3Al phase field has been systematically studied in these alloys. A wide variety of morphological features were found to be associated with the Nb3Al precipitates that formed in the bcc/B2 matrix during isothermal heat treatments. The lengthening kinetics of the plate-shaped Nb3Al precipitates were also studied.

  6. Radioactive 26Al and massive stars in the Galaxy

    E-print Network

    Roland Diehl; Hubert Halloin; Karsten Kretschmer; Giselher G. Lichti; Volker Schoenfelder; Andrew W. Strong; Andreas von Kienlin; Wei Wang; Pierre Jean; Juergen Knoedlseder; Jean-Pierre Roques; Georg Weidenspointner; Stephane Schanne; Dieter H. Hartmann; Christoph Winkler; Cornelia Wunderer

    2006-01-04

    Gamma-rays from radioactive 26Al (half life ~7.2 10^5 yr) provide a 'snapshot' view of ongoing nucleosynthesis in the Galaxy. The Galaxy is relatively transparent to such gamma-rays, and emission has been found concentrated along the plane of the Galaxy. This led to the conclusion1 that massive stars throughout the Galaxy dominate the production of 26Al. On the other hand, meteoritic data show locally-produced 26Al, perhaps from spallation reactions in the protosolar disk. Furthermore, prominent gamma-ray emission from the Cygnus region suggests that a substantial fraction of Galactic 26Al could originate in localized star-forming regions. Here we report high spectral resolution measurements of 26Al emission at 1808.65 keV, which demonstrate that the 26Al source regions corotate with the Galaxy, supporting its Galaxy-wide origin. We determine a present-day equilibrium mass of 2.8 (+/-0.8) M_sol of 26Al. We use this to estimate that the frequency of core collapse (i.e. type Ib/c and type II) supernovae to be 1.9(+/- 1.1) events per century.

  7. Creep of fully lamellar near {gamma}-TiAl intermetallics

    SciTech Connect

    Beddoes, J.; Zhao, L.; Chen, W.R.; Du, X.

    1999-07-01

    The influence of the fully lamellar morphology and third phase {beta} on the creep properties of near {gamma}-TiAl intermetallics is presented. Specifically, the effect of improved microstructural control obtainable by a stepped cool, involving furnace cooling and air cooling from the {alpha} single phase, on creep resistance is demonstrated for three near {gamma}-TiAl intermetallics: binary Ti-48Al, ternary Ti-48Al-2W and Ti-47Al-2Nb-1Mn-0.5W-0.5Mo-0.2Si. The results indicate that appropriate stepped cooling can be used to reduce the lamellar interface spacing without the formation of Widmanstaetten, feathery {gamma} or {gamma}{sub M} structures, leading to longer creep life and reduced creep strain rates. A second benefit of stepped cooling is prevention of {beta} formation during cooling from the {alpha} phase, allowing controlled {beta} precipitation during aging at 950 C. Creep tests on variously aged Ti-48Al-2W indicate that {beta} precipitation along lamellar grain boundaries improves creep resistance. Development of a uniform fully lamellar structure in Ti-47Al-2Nb-1Mn-0.5W-0.5Mo-0.2Si significantly improves creep resistance. Applying the stepped cool to this alloy allows the precipitation of {beta} and silicides to be controlled during lower temperature aging.

  8. Mechanism of oxygen adsorption on surfaces of ?-TiAl

    NASA Astrophysics Data System (ADS)

    Song, Y.; Dai, J. H.; Yang, R.

    2012-05-01

    We studied the adsorption behavior of oxygen on low index surfaces of ?-TiAl via first principles to investigate the mechanism that drives the adsorption behavior. The (100) surface is the most stable surface energetically followed by the (111), (110) and (001) surfaces. A study of the adsorption of a single oxygen atom on surfaces of TiAl showed that the O atom prefers the Ti-rich environment that has a high potential of generating TiO2. Competition between O-Al bonding and O-Ti bonding was observed in the O adsorbed surface regions. However, the O-Ti interaction dominates the adsorption behavior in all considered systems except when O is adsorbed on an Al-terminated (001) surface as the O-Al bond is stronger than O-Ti bond. A linear relationship between adsorption energy and integration of orbital overlaps between the O atom and the metals is obtained, which indicates that the electronic structure controls the adsorption behavior of an O atom on a ?-TiAl surface — an opportunity to improve the oxidation resistance of ?-TiAl based alloys.

  9. Radioactive 26Al from massive stars in the Galaxy.

    PubMed

    Diehl, Roland; Halloin, Hubert; Kretschmer, Karsten; Lichti, Giselher G; Schönfelder, Volker; Strong, Andrew W; von Kienlin, Andreas; Wang, Wei; Jean, Pierre; Knödlseder, Jürgen; Roques, Jean-Pierre; Weidenspointner, Georg; Schanne, Stephane; Hartmann, Dieter H; Winkler, Christoph; Wunderer, Cornelia

    2006-01-01

    Gamma-rays from radioactive 26Al (half-life approximately 7.2 x 10(5) years) provide a 'snapshot' view of continuing nucleosynthesis in the Galaxy. The Galaxy is relatively transparent to such gamma-rays, and emission has been found concentrated along its plane. This led to the conclusion that massive stars throughout the Galaxy dominate the production of 26Al. On the other hand, meteoritic data show evidence for locally produced 26Al, perhaps from spallation reactions in the protosolar disk. Furthermore, prominent gamma-ray emission from the Cygnus region suggests that a substantial fraction of Galactic 26Al could originate in localized star-forming regions. Here we report high spectral resolution measurements of 26Al emission at 1808.65 keV, which demonstrate that the 26Al source regions corotate with the Galaxy, supporting its Galaxy-wide origin. We determine a present-day equilibrium mass of 2.8 (+/- 0.8) solar masses of 26Al. We use this to determine that the frequency of core collapse (that is, type Ib/c and type II) supernovae is 1.9 (+/- 1.1) events per century. PMID:16397491

  10. The Cryptanalysis of Yuan et al.'s Multiparty Quantum Secret Sharing Protocol

    NASA Astrophysics Data System (ADS)

    Zhang, Kejia; Qin, Sujuan

    2013-11-01

    Recently, Yuan et al. summarized some previous analysis of quantum secret sharing task and designed a multiparty quantum secret sharing protocol based on the continuous variable operations (CVO) with the ideas of dense coding and ping-pong technique (YMQSS). However, our research shows that the YMQSS protocol is unable to complete the quantum secret sharing task securely if the particular participant, Bob0, is dishonest. In order to show that, we describe the following two attack strategies: one is that Bob0 can get the accurate shared secrets himself and leave the other sharers get his forged ones; the other one is that Bob0 can conspire with another sharer Bob i ( i?0) to get Alice’s secrets without anyone’s help. Finally, our discussions and conclusions are proposed.

  11. Alloy development and processing of FeAl: An overview

    SciTech Connect

    Maziasz, P.J.; Goodwin, G.M.; Alexander, D.J.; Viswanathan, S.

    1997-03-01

    In the last few years, considerable progress has been made in developing B2-phase FeAl alloys with improved weldability, room-temperature ductility, and high-temperature strength. Controlling the processing-induced microstructure is also important, particularly for minimizing trade-offs in various properties. FeAl alloys have outstanding resistance to high-temperature oxidation, sulfidation, and corrosion in various kinds of molten salts due to formation of protective Al{sub 2}O{sub 3} scales. Recent work shows that FeAl alloys are carburization-resistant as well. Alloys with 36 to 40 at. % Al have the best combination of corrosion resistance and mechanical properties. Minor alloying additions of Mo, Zr, and C, together with microalloying additions of B, produce the best combination of weldability and mechanical behavior. Cast FeAl alloys, with 200 to 400 {mu}m grain size and finely dispersed ZrC, have 2 to 5% tensile ductility in air at room-temperature, and a yield strength > 400 MPa up to about 700 to 750{degrees}C. Extruded ingot metallurgy (I/M) and powder metallurgy (P/M) materials with refined grain sizes ranging from 2 to 50 {mu}m, can have 10 to 15% ductility in air and be much stronger, and can even be quite tough, with Charpy impact energies ranging from 25 to 105 J at room-temperature. This paper highlights progress made in refining the alloy composition and exploring processing effects on FeAl for monolithic applications. It also includes recent progress on developing FeAl weld-overlay technology, and new results on welding of FeAl alloys. It summarizes some of the current industrial testing and interest for applications.

  12. Social Processes Explaining the Benefits of Al-Anon Participation

    PubMed Central

    Timko, Christine; Halvorson, Max; Kong, Calvin; Moos, Rudolf H

    2015-01-01

    This study examined social processes of support, goal direction, provision of role models, and involvement in rewarding activities to explain benefits of participating in Al-Anon, a 12-step mutual-help program for people concerned about another person’s substance use. Newcomers to Al-Anon were studied at baseline and 6 months later, when they were identified as having sustained attendance or dropped out. Among newcomers, and among established Al-Anon members (“oldtimers”), we also used number of Al-Anon meetings attended during follow-up to indicate extent of participation. Social processes significantly mediated between newcomers’ attendance status as sustained (versus dropped out) and outcomes of Al-Anon in the domains of life context (e.g., better quality of life, better able to handle problems due to the drinker), improved positive symptoms (more self-esteem, more hopeful), and decreased negative symptoms (e.g., less abuse, less depressed). Social processes also significantly mediated between newcomers’ number of meetings and outcomes. However, among oldtimers, Al-Anon attendance was not associated with outcomes, so the potential mediating role of social processes could not be examined, but social processes were associated with outcomes. Findings add to the growing body of work identifying mechanisms by which 12-step groups are effective, by showing that bonding, goal direction, and access to peers in recovery and rewarding pursuits help to explain associations between sustained Al-Anon participation among newcomers and improvements on key concerns of Al-Anon attendees. Al-Anon is free of charge and widely available, making it a potentially cost-effective public health resource in helping to alleviate negative consequences of concern about another’s addiction. PMID:26727006

  13. Social processes explaining the benefits of Al-Anon participation.

    PubMed

    Timko, Christine; Halvorson, Max; Kong, Calvin; Moos, Rudolf H

    2015-12-01

    This study examined social processes of support, goal direction, provision of role models, and involvement in rewarding activities to explain benefits of participating in Al-Anon, a 12-step mutual-help program for people concerned about another person's substance use. Newcomers to Al-Anon were studied at baseline and 6 months later, at which time they were identified as having either sustained attendance or dropped out. Among both newcomers and established Al-Anon members ("old-timers"), we also used number of Al-Anon meetings attended during follow-up to indicate extent of participation. Social processes significantly mediated newcomers' sustained attendance status versus dropped out and outcomes of Al-Anon in the areas of life context (e.g., better quality of life, better able to handle problems due to the drinker), improved positive symptoms (e.g., higher self-esteem, more hopeful), and decreased negative symptoms (e.g., less abuse, less depressed). Social processes also significantly mediated newcomers' number of meetings attended and outcomes. However, among old-timers, Al-Anon attendance was not associated with outcomes, so the potential mediating role of social processes could not be examined, but social processes were associated with outcomes. Findings add to the growing body of work identifying mechanisms by which 12-step groups are effective, by showing that bonding, goal direction, and access to peers in recovery and rewarding pursuits help to explain associations between sustained Al-Anon participation among newcomers and improvements on key concerns of Al-Anon attendees. Al-Anon is free of charge and widely available, making it a potentially cost-effective public health resource for help alleviating negative consequences of concern about another's addiction. (PsycINFO Database Record PMID:26727006

  14. Evaluation of Ti-48Al-2Nb Under Fretting Conditions

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Lerch, Bradley A.; Draper, Susan L.; Raj, Sai V.

    2001-01-01

    An investigation was conducted to examine the fretting behavior of lambda-TiAl (Ti-48Al-2Cr-2Nb) in contact with a nickel-base superalloy (Inconel 718) in air at temperatures from 23 to 550 C. Fretting wear experiments were conducted with 9.4-mm-diameter hemispherical Inconel (IN) 718 pins in contact with Ti-48Al-2Cr-2Nb flats (and the reverse) at loads from 1 to 40 N and fretting frequencies from 50 to 160 Hz with slip amplitudes from 50 to 200 microns for 1 to 20 million fretting cycles. The results were similar for both combinations of pin and flat. Reference fretting wear experiments were also conducted with 9.4-mm-diameter hemispherical Ti-6Al-4V pins in contact with IN718 flats. The interfacial adhesive bonds between Ti-48Al-2Cr-2Nb and IN718 in contact were generally stronger than the cohesive bonds in the cohesively weaker Ti-48Al-2Cr-2Nb. The failed Ti-48Al-2Cr-2Nb subsequently transferred to the IN718 surface at any fretting condition. The wear scars produced on Ti-48Al-2Cr-2Nb contained metallic and oxide wear debris, scratches, plastically deformed asperities, cracks, and fracture pits. Oxide layers readily formed on the Ti-48Al-2Cr-2Nb surface at 550 C, but cracks easily occurred in the oxide layers. Factors including fretting frequency, temperature, slip amplitude, and load influenced the fretting behavior of Ti-48Al-2Cr-2Nb in contact with IN718. The wear volume loss of Ti-48Al-2Cr-2Nb generally decreased with increasing fretting frequency. The increasing rate of oxidation at elevated temperatures up to 200 C led to a drop in wear volume loss at 200 C. However, the fretting wear increased as the temperature was increased from 200 to 550 C. The highest temperatures of 450 and 550 C resulted in oxide film disruption with generation of cracks, loose wear debris, and pits on the Ti-48Al-2Cr-2Nb wear surface. The wear volume loss generally increased as the slip amplitude increased. The wear volume loss also generally increased as the load increased. Increasing slip amplitude and increasing load both tended to produce more metallic wear debris, causing severe abrasive wear in the contacting metals.

  15. ALS user meeting features 10th anniversary celebration

    SciTech Connect

    Robinson, Art

    2003-12-05

    The Advanced Light Source (ALS) saw first light on October 5, 1993, not quite to the day but close to 10 years before the 2003 ALS Users Association meeting, held October 6-8. Fittingly, the proceedings included retrospectives from two of the key players in the early history of the ALS, David Attwood and Jay Marx, and a display of photographs chronicling its construction and commissioning. Science highlights, highlights from young researchers, and posters constituted the meat of the program on Monday and Tuesday morning, while workshops took over Tuesday afternoon and all day Wednesday.

  16. Mercury embrittlement of Cu-Al alloys under cyclic loading

    NASA Technical Reports Server (NTRS)

    Regan, T. M.; Stoloff, N. S.

    1977-01-01

    The effect of mercury on the room temperature, high cycle fatigue properties of three alloys: Cu-5.5 pct Al, Cu-7.3 pct Al, and Cu-6.3 pct Al-2.5 pct Fe has been determined. Severe embrittlement under cyclic loading in mercury is associated with rapid crack propagation in the presence of the liquid metal. A pronounced grain size effect is noted under mercury, while fatigue properties in air are insensitive to grain size. The fatigue results are discussed in relation to theories of adsorption-induced liquid metal embrittlement.

  17. Inversion domains in AlN grown on (0001) sapphire

    SciTech Connect

    Jasinski, J.; Liliental-Weber, Z.; Paduano, Q.S.; Weyburne, D.W.

    2003-08-25

    Al-polarity inversion domains formed during AlN layer growth on (0001) sapphire were identified using transmission electron microscopy (TEM). They resemble columnar inversion domains reported for GaN films grown on (0001) sapphire. However, for AlN, these columns have a V-like shape with boundaries that deviate by 2 {+-} 0.5{sup o} from the c-axis. TEM identification of these defects agrees with the post-growth surface morphology as well as with the microstructure revealed by etching in hot aqueous KOH.

  18. Pressure-induced structural transition in AlN nanowires

    NASA Astrophysics Data System (ADS)

    Shen, L. H.; Li, X. F.; Ma, Y. M.; Yang, K. F.; Lei, W. W.; Cui, Q. L.; Zou, G. T.

    2006-10-01

    The structural transition of AlN nanowires was investigated under pressures up to 51.1GPa by in situ angle dispersive high-pressure x-ray diffraction using synchrotron radiation source and a diamond anvil cell. A pressure-induced wurtzite to rocksalt phase transition starts at 24.9GPa and completes at 45.4GPa. The high-pressure behaviors of AlN nanowires differing from the bulk and nanocrystal AlN might arise from the intrinsic geometry in nanowires.

  19. Nucleation in Al Alloys Processed By MCDC Casting

    NASA Astrophysics Data System (ADS)

    Prasada Rao, A. K.

    2015-06-01

    Present work confines itself to discuss the mechanism responsible for the grain refinement of the melt conditioned direct-chill cast aluminum alloys. It has been found that the Al alloys processed by this process undergo grain refinement irrespective of their chemical composition. The forced convection caused during this process led to dendrite fragmentation which enhances the heterogeneous nucleation and result in grain refinement. It is suggested that owing to their favorable lattice matching with ?-Al, these fragments serve as potent nuclei for ?-Al grains.

  20. Dislocations in extruded Co-49.3 at. pct Al

    NASA Technical Reports Server (NTRS)

    Yaney, D. L.; Nix, W. D.; Pelton, A. R.

    1986-01-01

    Polycrystalline Co-49.3 at. pct Al, which had been extruded at 1505 K, was examined using transmission electron microscopy. Diffraction contrast analysis showed that b = 100 as well as b = 111 line dislocations contribute to elevated temperature deformation in CoAl. Therefore, it was concluded that sufficient slip systems exist in CoAl to allow for general plasticity in the absence of diffusional mechanisms. Line dislocations of the type b = 001 were observed on both 110 and 100 planes while b = 111 line dislocations were observed on 1 -1 0 planes.

  1. Thermal expansion of rock-salt cubic AlN

    NASA Astrophysics Data System (ADS)

    Bartosik, M.; Todt, M.; Holec, D.; Todt, J.; Zhou, L.; Riedl, H.; Böhm, H. J.; Rammerstorfer, F. G.; Mayrhofer, P. H.

    2015-08-01

    We combine continuum mechanics modeling and wafer curvature experiments to characterize the thermal expansion coefficient of AlN in its metastable cubic rock-salt (B1) structure. The latter was stabilized as nm thin layers by coherency strains in CrN/AlN epitaxial multilayers deposited on Si (100) substrates using reactive magnetron sputtering. The extraction of the B1-AlN thermal expansion coefficient, from experimentally recorded temperature dependent wafer curvature data, is formulated as an inverse problem using continuum mechanics modeling. The results are cross-validated by density functional theory calculations.

  2. Synthesis, characterization and mechanical properties of nanocrystalline NiAl

    SciTech Connect

    Choudry, M. |; Eastman, J.A.; DiMelfi, R.J.; Dollar, M.

    1996-11-01

    Nanocrystalline NiAl was produced from pre-cast alloys using an electron beam inert gas condensation system. In-situ compaction was carried out at 100-300 C under vacuum conditions. Energy dispersive spectroscopy was used to determine chemical composition and homogeneity. Average grain sizes in the range 4-10 nm were found from TEM dark field analyses. A compression-cage fixture was designed to perform disk bend tests. These tests revealed substantial room temperature ductility in nanocrystalline NiAl, while coarse grained NiAl showed no measurable room temperature ductility.

  3. Lattice crossover and phase transitions in NdAlO{sub 3}-GdAlO{sub 3} system

    SciTech Connect

    Vasylechko, L.; Shmanko, H.; Ohon, N.; Prots, Yu.; Hoffmann, S.; Ubizskii, S.

    2013-02-15

    Phase and structural behaviour in the (1-x)NdAlO{sub 3}-xGdAlO{sub 3} system in a whole concentration range has been studied by means of in situ high-resolution X-ray synchrotron powder diffraction technique and differential thermal analysis. Two kinds of solid solutions Nd{sub 1-x}Gd{sub x}AlO{sub 3} have been found at room temperature: one with rhombohedral (x<0.15) and one with orthorhombic (x{>=}0.20) symmetry. A morphotropic phase transition occurs at x Almost-Equal-To 0.15, where the co-existence of both phases was observed. Peculiarity of the orthorhombic solid solution is the lattice parameter crossover at the compositions with x=0.33, 0.49 and 0.62. First-order structural transition Pbnm{r_reversible}R3{sup Macron }c has been detected both from in situ powder diffraction and thermal analysis data. Continuous phase transformation R3{sup Macron }c{r_reversible}Pm3{sup Macron }m above 2140 K has been predicted for Nd-rich sample Nd{sub 0.85}Gd{sub 0.15}AlO{sub 3} from the extrapolation of high-temperature behaviour of the lattice parameter ratio of the rhombohedral phase. Based on the experimental data, the phase diagram of the pseudo-binary system NdAlO{sub 3}-GdAlO{sub 3} has been constructed. - Graphical abstract: Concentration dependencies of normalized lattice parameters of Nd{sub 1-x}Gd{sub x}AlO{sub 3} perovskite solid solutions. Highlights: Black-Right-Pointing-Pointer Two kinds of solid solutions Nd{sub 1-x}Gd{sub x}AlO{sub 3} were found in the NdAlO{sub 3}-GdAlO{sub 3} system. Black-Right-Pointing-Pointer Morphotropic transition between both perovskite phases occurs at x Almost-Equal-To 0.15. Black-Right-Pointing-Pointer Lattice parameter crossover was found in orthorhombic solid solution. Black-Right-Pointing-Pointer Temperature driven first-order phase transition Pbnm{r_reversible}R3{sup Macron }c was found in Nd{sub 1-x}Gd{sub x}AlO{sub 3}. Black-Right-Pointing-Pointer Phase diagram of the pseudo-binary system NdAlO{sub 3}-GdAlO{sub 3} has been constructed.

  4. Role of nanoscale AlN and InN for the microwave characteristics of AlGaN/(Al,In)N/GaN-based HEMT

    SciTech Connect

    Lenka, T. R. Panda, A. K.

    2011-09-15

    A new AlGaN/GaN-based high electron mobility transistor (HEMT) is proposed and its micro-wave characteristics are discussed by introducing a nanoscale AlN or InN layer to study the potential improvement in their high frequency performance. The 2DEG transport mechanism including various sub-band calculations for both (Al,In) N-based HEMTs are also discussed in the paper. Apart from direct current characteristics of the proposed HEMT, various microwave parameters such as transconductance, unit current gain (h{sub 21} = 1) cut-off frequency (f{sub t}), high power-gain frequency (f{sub max}). Masons available/stable gain and masons unilateral gain are also discussed for both devices to understand its suitable deployment in microwave frequency range.

  5. Effects of H2 plasma and annealing on atomic-layer-deposited Al2O3 films and Al/Al2O3/Si structures

    NASA Astrophysics Data System (ADS)

    Choi, Kyeong-Keun; Kee, Jong; Park, Chan-Gyung; Kim, Deok-kee

    2015-04-01

    We evaluated the effects of H2 plasma and thermal treatment on current-voltage (I-V) and capacitance-voltage (C-V) characteristics using Al/Al2O3/Si. H2 plasma treatment reduced the concentration of C and enhanced the diffusion of Si and O atoms and the mean breakdown field strength. The breakdown field increased significantly after rapid thermal annealing (RTA) due to crystallization and the formation of an interface layer between Si and Al2O3, which was confirmed by TEM, secondary ion mass spectroscopy (SIMS), and three-dimensional (3D) atom probe tomography. H2 plasma treatment produced a negative fixed charge due to the outgassing of C and H2, and RTA produced a positive fixed charge.

  6. The effect of mineral paragenesis on Al diffusion in olivine

    NASA Astrophysics Data System (ADS)

    Zhukova, Irina; O'Neill, Hugh; Capbell, Ian

    2014-05-01

    Al is the most abundant trivalent impurity of olivine and is particularly important because its concentration in olivine is temperature dependant, and it therefore has potential as a geothermometer (Wan, et al. 2008). Furthermore recent studies show that the incorporation of water into the olivine lattice is affected by the presents of trivalent cations such as Al3+ (Berry, et al. 2007; Hauri, et al. 2006). The Al distribution in olivines from volcanic rocks is often zoned and mantle olivines may also show an inhomogeneous distribution of Al, whereas the majority of other trace elements homogenized by diffusion (Mallmann, et al. 2009; McKibbin, et al.). However, there are no quantitative experimental data for Al diffusion in olivine, probably because the combination of low concentration rate and low diffusion rate make measurement difficult. We investigated the effect of silica activity on the diffusion rate of Al in forsterite at varying temperatures using solid-state buffer assemblages. Our study aimed to quantify the effect of major cation activities on the diffusion and concentration of Al in forsterite and also provide insights into the mechanism of Al substitution into the olivine lattice. The activities of SiO2, MgO and Al2O3 were buffered in each experiment by four different mineral associations: forsterite + periclase + spinel (fo+per+sp); forsterite + spinel + sapphirine (fo+sp+spr); forsterite + sapphirine + cordierite (fo+spr+cor); forsterite + cordierite + enstatite (fo+cor+en). Iron oxide in proportion of FeO/(FeO+MgO) = 0.1 was added to mixtures for San Carlos olivine experiments. Diffusion experiments were performed at the one-atmosphere vertical tube furnaces modified to control the fO2 by CO-CO2 gas mixing or in a box furnace in air for 10 - 28 days at temperatures from 1100 to 1500oC and logfO2 -0.7 and -5.7. The experiment with the San Carlos olivine was performed at 1300oC and at logfO2 = -5.7. In order to obtain equilibrium concentrations of the point defects we performed some experiments with pre-annealing. Diffusion profiles were measured by LA-ICP-MS in a traverse mode. The Al content of forsterite decreases with temperature dependence, increasing the potential of Al in olivine as a geothermometer. We obtain the activation energy of 379 kJ/mol for the high aSiO2 experiments, which is close within error of the value of 364 kJ/mol for the low aSiO2 experiments implying a common diffusion mechanism. The pre-exponential factor, however, increases by 5 orders of magnitude from low aSiO2 (fo+per+sp buffer) to high aSiO2 (fo+cor+en buffer). The much higher diffusivity at high aSiO2 indicates that Al diffusion occurs through octahedral cation site vacancies.

  7. Two-dimensional electron gases in strained quantum wells for AlN/GaN/AlN double heterostructure field-effect transistors on AlN

    SciTech Connect

    Li, Guowang; Song, Bo; Ganguly, Satyaki; Zhu, Mingda; Wang, Ronghua; Yan, Xiaodong; Verma, Jai; Protasenko, Vladimir; Grace Xing, Huili; Jena, Debdeep

    2014-05-12

    Double heterostructures of strained GaN quantum wells (QWs) sandwiched between relaxed AlN layers provide a platform to investigate the quantum-confined electronic and optical properties of the wells. The growth of AlN/GaN/AlN heterostructures with varying GaN quantum well thicknesses on AlN by plasma molecular beam epitaxy (MBE) is reported. Photoluminescence spectra provide the optical signature of the thin GaN QWs. Reciprocal space mapping in X-ray diffraction shows that a GaN layer as thick as ?28 nm is compressively strained to the AlN layer underneath. The density of the polarization-induced two-dimensional electron gas (2DEG) in the undoped heterostructures increases with the GaN QW thickness, reaching ?2.5?×?10{sup 13}/cm{sup 2}. This provides a way to tune the 2DEG channel density without changing the thickness of the top barrier layer. Electron mobilities less than ?400 cm{sup 2}/Vs are observed, leaving ample room for improvement. Nevertheless, owing to the high 2DEG density, strained GaN QW field-effect transistors with MBE regrown ohmic contacts exhibit an on-current density ?1.4?A/mm, a transconductance ?280 mS/mm, and a cut off frequency f{sub T}?104?GHz for a 100-nm-gate-length device. These observations indicate high potential for high-speed radio frequency and high voltage applications that stand to benefit from the extreme-bandgap and high thermal conductivity of AlN.

  8. High internal quantum efficiency in AlGaN multiple quantum wells grown on bulk AlN substrates

    SciTech Connect

    Bryan, Zachary Bryan, Isaac; Sitar, Zlatko; Collazo, Ramón; Xie, Jinqiao; Mita, Seiji

    2015-04-06

    The internal quantum efficiency (IQE) of Al{sub 0.55}Ga{sub 0.45}N/AlN and Al{sub 0.55}Ga{sub 0.45}N/Al{sub 0.85}Ga{sub 0.15}N UVC MQW structures was analyzed. The use of bulk AlN substrates enabled us to undoubtedly distinguish the effect of growth conditions, such as V/III ratio, on the optical quality of AlGaN based MQWs from the influence of dislocations. At a high V/III ratio, a record high IQE of ?80% at a carrier density of 10{sup 18?}cm{sup ?3} was achieved at ?258?nm. The high IQE was correlated with the decrease of the non-radiative coefficient A and a reduction of midgap defect luminescence, all suggesting that, in addition to dislocations, point defects are another major factor that strongly influences optical quality of AlGaN MQW structures.

  9. Emergent phenomena in LaAlO3 /GdAlO3 superlattices by breaking inversion symmetry

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Tian; Haislmaier, Ryan; Lapano, Jason; Gopalan, Venkatraman; Engel-Herbert, Roman

    2015-03-01

    Recently, tremendous interest has been focused on materials by design, where hybrid improper ferroelectricity was proposed from first principles predictions in perovskite superlattice structures (ABO3)n/(A'BO3)m , which is directly coupled to the oxygen octahedral rotations [1]. Such oxygen octahedron rotations are anticipated stable at high temperatures, thus being a potential materials candidate for high temperature piezoelectric sensor and transducer applications. In this talk we will present the homoepitaxial growth of LaAlO3 and GaAlO3 by hybrid molecular beam epitaxy, where a volatile aluminium alkoxide precursor and elemental La/Gd (flux 2 × 1013 cm-2s-1) were co-supplied in the presence of an oxygen plasma (RF plasma power 250 W). Growth mode, film surface morphology and defect type for films grown under La/Gd-rich and Al-rich growth conditions will be discussed and directly related to structure and properties characterization of the LaAlO3 and GaAlO3. Changes in the octahedral tilts, probed by scanning transmission electron microscopy in the proximity of GdAlO3/LaAlO3 interface are discussed and compared to first principle predictions.

  10. Phase transformations, heat evolution, and atomic diffusion during slow heating of Al-rich Al/Zr multilayered foils

    SciTech Connect

    Fisher, Kaitlynn; Barron, S. C.; Knepper, R.; Weihs, T. P.; Bonds, M. A.; Browning, N. D.; Livi, K. J. T.; Campbell, G. H.

    2013-12-28

    We describe the energy and sequence of phase transformations in multilayered Al/Zr foils with atomic ratios of 3 Al:1 Zr during low temperature (<350?°C) heat treatments in a differential scanning calorimeter. The initial phase formed is an Al-rich amorphous phase that appears to grow by Zr diffusion through the amorphous phase. The subsequent nucleation and growth of tetragonal Al{sub 3}Zr along the Al/amorphous layer interface is mediated by Al diffusion through the crystalline intermetallic phase. Diffusion coefficients associated with these processes are higher than expected from reports of diffusivities measured at higher temperatures. The inferred heat of formation of the tetragonal Al{sub 3}Zr phase is 1240?±?40?J/g (53?±?2?kJ/mol atom). No anomalous variation in the energy or sequence of phase transformations is found with bilayer thickness for samples with bilayer thickness in the range of 17?nm to 90?nm despite anomalies in the bilayer dependence of self-propagating reaction velocities in the same foils.

  11. Oxidation Behavior of Thermal Barrier Coatings with a TiAl3 Bond Coat on ?-TiAl Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Jiqiang; Kong, Lingyan; Li, Tiefan; Xiong, Tianying

    2015-02-01

    The thermal barrier coatings investigated in this paper included a TiAl3 bond coat and a yttria partially stabilized zirconia (YSZ) layer. The TiAl3 bond coat was prepared by deposition of aluminum by cold spray, followed by a heat-treatment. The YSZ layer was prepared by air plasma spray. The isothermal and cyclic oxidation tests were conducted at 900 °C for 1000 h and 500 cycles to test the oxidation resistance of the thermal barrier coatings. The microstructure and composition of the ?-TiAl alloy with and without the thermal barrier coatings after oxidation were investigated. The results showed that a dense TGO layer about 5 ?m had grown between the YSZ layer and the TiAl3 bond coat. The TGO had good adhesion to both the YSZ layer and the bond coat even after the TiAl3 bond coat entirely degraded into the TiAl2 phase, which decreased the inward oxygen diffusion. Thus, the thermal barrier coatings improved the oxidation resistance of ?-TiAl alloy effectively.

  12. Investigation of the site occupation of atoms in pure and doped TiAl/Ti3Al intermetallic.

    PubMed

    Boll, T; Al-Kassab, T; Yuan, Y; Liu, Z G

    2007-09-01

    Dual-phase TiAl/Ti3Al-alloys consisting of a lamellar structure, comprising gamma-phase plus a small amount of alpha2-phase, with addition of 1, 5 and 10at% Nb were prepared. The samples were investigated by means of field ion microscopy (FIM) and atom probe tomography (APT). The influence of doping elements on the variation of field evaporation and microstructural parameters in the gamma-phase as studied by FIM and APT will be reported in this contribution. The intermetallic gamma-Phase of TiAl exhibits a L1(0)-structure, which has alternating Ti- and Al-planes in the [001]-superstructure direction. Because of the significant difference in the evaporation field strengths of Ti and Al, it is usually not possible to directly distinguish Ti- and Al-planes in this direction in the APT data. Therefore, it is not possible to assign Nb to any plane, as well. To solve this problem an algorithm, using statistical methods, was developed, which allows to inherently distinguish the planes. A comparison of the results for [100]- and [001]-directions shows that Nb prefers Ti-sites. The sequence of field evaporation field strengths, which follows the trend E(Nb) > E(Al) > E(Ti), could also be deduced. PMID:17482365

  13. NiAl-based Polyphase in situ Composites in the NiAl-Ta-X (X = Cr, Mo, or V) Systems

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    Polyphase in situ composites were generated by directional solidification of ternary eutectics. This work was performed to discover if a balance of properties could be produced by combining the NiAl-Laves phase and the NiAl-refractory metal phase eutectics. The systems investigated were the Ni-Al-Ta-X (X = Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and the eutectic composition, temperature, and morphology were determined. The ternary eutectic systems examined were the NiAl-NiAlTa-(Mo, Ta), NiAl-(Cr, Al) NiTa-Cr, and the NiAl-NiAlTa-V systems. Each eutectic consists of NiAl, a C14 Laves phase, and a refractory metal phase. Directional solidification was performed by containerless processing techniques in a levitation zone refiner to minimize alloy contamination. Room temperature fracture toughness of these materials was determined by a four-point bend test. Preliminary creep behavior was determined by compression tests at elevated temperatures, 1100-l400 K. Of the ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr, Al)NiTa-Cr eutectic was intermediate between the values of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

  14. Comment on the narrow structure reported by Amaryan et al

    E-print Network

    M. Anghinolfi; J. Ball; N. A. Baltzell; M. Battaglieri; I. Bedlinskiy; M. Bellis; A. S. Biselli; C. Bookwalter; S. Boiarinov; P. Bosted; V. D. Burkert; D. S. Carman; A. Celentano; S. Chandavar; P. L. Cole; V. Crede; R. De Vita; E. De Sanctis; B. Dey; R. Dickson; D. Doughty; M. Dugger; R. Dupre; H. Egiyan; A. El Alaoui; L. El Fassi; L. Elouadrhiri; P. Eugenio; G. Fedotov; M. Y. Gabrielyan; M. Garcon; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; E. Golovatch; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; D. Heddle; K. Hicks; M. Holtrop; D. G. Ireland; B. S. Ishkhanov; E. L. Isupov; H. S. Jo; K. Joo; P. Khetarpal; A. Kim; W. Kim; V. Kubarovsky; S. V. Kuleshov; H. Y. Lu; L. J. D. MacGregor; N. Markov; M. E. McCracken; B. McKinnon; M. D. Mestayer; C. A. Meyer; M. Mirazita; V. Mokeev; K. Moriya; B. Morrison; A. Ni; S. Niccolai; G. Niculescu; I. Niculescu; M. Osipenko; A. I Ostrovidov; K. Park; S. Park; S. Anefalos Pereira; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; G. Ricco; M. Ripani; B. G. Ritchie; P. Rossi; D. Schott; R. A. Schumacher; E. Seder; Y. G. Sharabian; E. S. Smith; D. I Sober; S. S. Stepanyan; P. Stoler; W. Tang; M. Ungaro; B. Vernarsky; M. F. Vineyard; D. P. Weygand; M. H. Wood; N. Zachariou; B. Zhao

    2012-04-05

    The CLAS Collaboration provides a comment on the physics interpretation of the results presented in a paper published by M. Amaryan et al. regarding the possible observation of a narrow structure in the mass spectrum of a photoproduction experiment.

  15. 76 FR 20727 - National Life Insurance Company, et al.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-13

    ... COMMISSION National Life Insurance Company, et al. April 7, 2011. AGENCY: Securities and Exchange Commission... Act of 1940 (the ``1940 Act''). Applicants: National Life Insurance Company (``NLIC''), National Variable Annuity Account II (``Annuity Account''), National Variable Life Insurance Account (``Life...

  16. Large magnetocaloric effect of GdNiAl2 compound

    NASA Astrophysics Data System (ADS)

    Dembele, S. N.; Ma, Z.; Shang, Y. F.; Fu, H.; Balfour, E. A.; Hadimani, R. L.; Jiles, D. C.; Teng, B. H.; Luo, Y.

    2015-10-01

    This paper presents the structure, magnetic properties, and magnetocaloric effect of the polycrystalline compound GdNiAl2. Powder X-ray diffraction (XRD) measurement and Rietveld refinement revealed that GdNiAl2 alloy is CuMgAl2-type phase structure with about 1 wt% GdNi2Al3 secondary phase. Magnetic measurements suggest that the compound is ferromagnetic and undergoes a second-order phase transition near 28 K. The maximum value of magnetic entropy change reaches 16.0 J/kg K for an applied magnetic field change of 0-50 kOe and the relative cooling power was 6.4×102 J/kg. It is a promising candidate as a magnetocaloric material working near liquid hydrogen temperature (~20 K) exhibiting large relative cooling power.

  17. 77 FR 40265 - Drawbridge Operation Regulation; Tennessee River, Decatur, AL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-09

    ... across the Tennessee River, mile 304.4, at Decatur, AL. The deviation is necessary to install new rail... requested a temporary deviation for the Southern Railroad Drawbridge, across the Tennessee River, mile...

  18. Fission induced swelling of U-Mo/Al dispersion fuel

    NASA Astrophysics Data System (ADS)

    Kim, Yeon Soo; Jeong, G. Y.; Park, J. M.; Robinson, A. B.

    2015-10-01

    Fission-induced swelling of U-Mo/Al dispersion fuel meat was measured using microscopy images obtained from post-irradiation examination. The data of reduced-size plate-type test samples and rod-type test samples were employed for this work. A model to predict the meat swelling of U-Mo/Al dispersion fuel was developed. This model is composed of several submodels including a model for interaction layer (IL) growth between U-Mo and Al matrix, a model for IL thickness to IL volume conversion, a correlation for the fission-induced swelling of U-Mo alloy particles, a correlation for the fission-induced swelling of IL, and models of U-Mo and Al consumption by IL growth. The model was validated using full-size plate data that were not included in the model development.

  19. The dual roles of immunity in ALS: injury overrides protection.

    PubMed

    Murdock, Benjamin J; Bender, Diane E; Segal, Benjamin M; Feldman, Eva L

    2015-05-01

    Amyotrophic lateral sclerosis (ALS) is a progressive, fatal neurodegenerative disease affecting motor neurons. Disease progression is accompanied by a multi-phased immune response, and recent studies indicate that the immune system is not simply a bystander during disease, but plays an active role in shaping ALS pathology. The role of the immune system during ALS progression is highly complex, however, as it has been found to have a role in both enhancing neurodegeneration as well as protecting the central nervous system. Previous reports have established that the immune response can therefore be separated into two distinct phases: a protective Type 2 response followed by a neurotoxic Type 1 response. This review will address the two phases of the immune response in ALS and describe their roles during disease progression. More importantly, it will also examine the likely sources of immune polarization that are responsible for shifting immunity from the protective T2 phase to the neurotoxic T1 phase. PMID:25726748

  20. Interface reaction and characterization in B/Al composites

    NASA Technical Reports Server (NTRS)

    Kim, W. H.; Koczak, M. J.; Lawley, A.

    1978-01-01

    Interfacial reactions, strength degradation, and fracture morphology have been characterized in B/Al(1100) and B/Al(6061) composite systems at a volume fraction of 0.55. Reaction was promoted by isothermal exposure at 350 C or 500 C for times up to 860,000 s. Tetragonal AlB12 was identified as the reaction product in the 6061 matrix and hexagonal AlB2 in the 1100 matrix. Interface development is analyzed based on a moving boundary model modified by the addition of ternary elements. While strength decreases in both systems, the time dependence of elevated-temperature exposure is different in the two matrix materials. In the 45 deg fiber orientation, failure occurs primarily by matrix shear, whereas in the 90 deg fiber orientation, fracture morphology is characterized by a mixture of fiber splitting, ductile matrix fracture, and failure at fiber-matrix interfaces.