WorldWideScience

Sample records for vantaggi che si

  1. Tempi che cambiano, luoghi che si trasformano: i mutamenti nei nuraghi fra l’età del Bronzo ed il Primo Ferro

    Directory of Open Access Journals (Sweden)

    Mauro Perra

    2017-01-01

    Full Text Available Riassunto: Il lungo percorso della Civiltà Nuragica, compreso fra XVII e X-IX secolo a.C., si caratterizza come un’epoca di grandi trasformazioni che si susseguono nel tempo e lasciano visibili tracce in un paesaggio mutevole, come in un succedersi di macroscopiche unità stratigrafiche. Si trasformano profondamente così non solo i monumenti ed il paesaggio, ma anche le stesse strutture sociali e politiche delle comunità nuragiche fino alla trasfigurazione del ricordo in mito nei centri cerimoniali o santuari. Abstract: The long trajectory of the Nuragic civilisation (17th - 10th/9th centuries B.C. is characterised by a succession of dramatic changes leaving visible traces in a varying landscape, like stratigraphy on a regional scale. These changes affect not only the Nuragic monuments and landscape but also the social and political institutions of Nuragic communities, culminating in a transfiguration of memory and a new mythology apparent in ceremonial centres and sanctuaries.

  2. La chiesa che si fa presepe: visita al Presepe della Chiesa del Rosario di Mottola

    Directory of Open Access Journals (Sweden)

    Susy Bigontina

    2012-01-01

    Full Text Available Abstract – IT In occasione del Natale, la vie della città di Mottola (Ta, Italia fioriscono di presepi, che i visitatori possono liberamente ammirare. Quella del presepe è una tradizione molto sentita dagli abitanti della cittadina pugliese, nella quale viene allestito un grande presepe che occupa e cela l’intera navata della Chiesa del Ss. Sacramento e Rosario. Gli allestitori, appartenenti ad una storica Confraternita locale dedicano settimane a costruire un presepe plastico della Betlemme nella notte di Natale, che mescola icone della tradizione italiana della Natività – alcuni pezzi, ad esempio, sono preziosi manufatti di scuola napoletana – ed elementi naturali tipici della terra delle gravine. Il presepe del Rosario, inoltre, mostra un’interessante ricerca dell’effetto prospettico e forse un ancor più interessante cornice di ciclicità, ottenuta tramite l’alternanza del giorno e della notte, musica ed effetti sonori, che proietta la scena verso un orizzonte atemporale. Questo articolo nasce dalla visita degli autori a Mottola, in occasione della presentazione del libro La Settimana Santa a Mottola, di cui essi sono stati co-autori, e quindi rappresenta il frutto di un nuovo capitolo di lavoro con la viva comunità mottolese ed i suoi riti. Abstract – FR Pour l'occasion de Noël, les rues de la villes de Mottola (Ta, Italie sont embellies de crèches que les visiteurs peuvent admirer en toute liberté. La tradition de la crèche est une tradition très ressentie par les habitants de la petite ville pugliaise, dans laquelle on prépare une grande crèche qui occupe et cache tout le nef de l'église du très Ss. Sacramento e Rosario. Les préparateurs qui appartiennent à une Confrérie historique locale dédient plusieurs semaines pour la construction d'une crèche comme celle de Betleemme de la nuit de Noël - certaines pièces, par exemple, sont de précieux produits manufacturés provenant de l'école napolitaine - et

  3. Che Guevara

    DEFF Research Database (Denmark)

    Cristoffanini, Pablo Rolando

    2014-01-01

    made Che Guevara a political, religious and cultural icon and an object of consumption, despite his total political and military failure in Bolivia and his violent death. Finally the article contrasts the meanings of his image in the original context with new research that calls into question...... with the achievements and connotations of the Cuban Revolution in the context of the Cold War. The current meanings of the image must be read in the context of the global consumer culture. The article analyzes and explains how a conjunction of factors such as communication strategies and the connotations of his image...

  4. El humanismo del Che Che's Humanism

    OpenAIRE

    Avelino Fernández Espert; Cristina Fernández Rivero

    2004-01-01

    Los autores, estudiosos de la raigal influencia del pensamiento y la obra del Comandante Dr. Ernesto Guevara de la Serna (Che) en Cuba y América, proyectan la estampa humanista de este revolucionario médico, con el empleo de las más trascendentes pinceladas históricas de un amplia hoja de vida en distintas latitudes del mundo. El Che, joven estudiante, médico graduado con prometedoras dotes que sabe ubicar al ser humano y sus valores por encima de un promisorio futuro como científico y profes...

  5. Sostenere le produzioni cinematografiche: vantaggi fiscali e di immagine per gli investitori / Sustaining cinematographic productions: fiscal and image opportunities for investors

    Directory of Open Access Journals (Sweden)

    Katia Giusepponi

    2016-05-01

    Full Text Available Questo contributo è focalizzato su organizzazioni non appartenenti al settore cinematografico, osservate nel loro ruolo di investitori esterni. L’importanza del valore collettivo di sostenere le produzioni cineaudiovisive è alla base del presente lavoro. Tuttavia la nostra attenzione è qui rivolta, da un lato, a studiare i vantaggi dell’investimento per l’azienda esterna, dall’altro, ad analizzarne i rischi nella prospettiva di una sempre più chiara consapevolezza di scelta. Dall’analisi di strumenti, dinamiche e dati emergono opportunità rilevanti per l’azienda, insieme a condizioni importanti per utilizzarle con successo. È essenziale che l’organizzazione proceda senza improvvisare, curando, da un lato, un approccio alla pianificazione e alla dettagliata valutazione del progetto, dall’altro, flessibilità e apertura nelle interazioni con gli altri interlocutori, interazioni che devono essere orientate al raggiungimento dell’equilibrio migliore a livello collettivo e individuale. Soprattutto, è necessario che l’azienda proceda nel contesto di un percorso strategico solido e coerente, perché un progetto di film può valorizzare l’identità aziendale ma non risolvere incertezze a questo riguardo.   This contribution focuses on organisations that are not in the cinema industry, studied in their role as external investors. The importance of the collective value of sustaining cine audio visual productions is at the basis of this work. Nonetheless, our attention is oriented, on one hand, to study the investment advantages for the external organization, on the other, to analyse the risks of this investment in the perspective of an increasingly clear choice. From the analysis of tools, dynamics and data, relevant opportunities for the organisation emerge, together with important conditions for their successful implementation. It is essential that the organization proceed without improvising, following, on one side, an

  6. El humanismo del Che Che's Humanism

    Directory of Open Access Journals (Sweden)

    Avelino Fernández Espert

    2004-08-01

    Full Text Available Los autores, estudiosos de la raigal influencia del pensamiento y la obra del Comandante Dr. Ernesto Guevara de la Serna (Che en Cuba y América, proyectan la estampa humanista de este revolucionario médico, con el empleo de las más trascendentes pinceladas históricas de un amplia hoja de vida en distintas latitudes del mundo. El Che, joven estudiante, médico graduado con prometedoras dotes que sabe ubicar al ser humano y sus valores por encima de un promisorio futuro como científico y profesional de la medicina. El artículo dedica atención especial a sus conceptos sobre el hombre, su vida e historia y a su proverbial apego a una ética revolucionaria de elevado calibre. El artículo contribuye al enriquecimiento de los conocimientos sobre el desarrollo histórico del humanismo médico cubano, al proyectarlo en la figura de uno de sus más míticos modelosThe authors, studious of the extraordinary influence of Commandant and Dr. Ernesto Guevara de la Serna 's thought in Cuba and America, unveil the humanist perspective of this revolutionary doctor, through the most transcendental historical events in this man's life in different latitudes of the world. Che, young student, medicine doctor with promising gifts that knew how to place the human being and his values above his promissory future as scientific and medicine professional. The article dedicates special attention to his concepts about men, as well as his life and history and to his proverbial attachment to valuable revolutionary ethics. The article contributes to the enrichment of knowledge on the historical development of Cuban medical humanism, by reflecting this in the figure of one of its most mythical models

  7. Notas sobre el che

    Directory of Open Access Journals (Sweden)

    Virginia Bertolotti

    2010-06-01

    Full Text Available In the present work, I review, in the first place, the bibliography that summarizes the discussion surrounding the etymology of the word che. Then, I analyze the uses of this term in the diachrony as in the synchrony of the Río de la Plata Spanish, which allows me to propose a classification of the uses of the word che in this region. In the third part of the article, I discuss the categorial adscrption of the word che. Finally, the categorial analysis of the diachronic and synchronic empirical evidence allows me to conclude that the vocative uses of the term are a loan from the nominal determinant of the guaraní language, and not a phonic change in the Spanish interjection, thus resolving the etymological issues.

  8. Che cos’è l’antiziganismo?

    Directory of Open Access Journals (Sweden)

    Leonardo Piasere

    2012-01-01

    Full Text Available Abstract – IT Chi è zingaro? Colui che chiamo zingaro, che assegno a questa identità e che costituisco come "altro" dal resto della società. In questo senso, la storia degli zingari si confonde con quella dell'"antiziganismo", un neologismo che denota una pratica antica. Ma si può dire che la comparsa della nuova parola è legata agliodierni intrecci tra politiche multiculturali da un lato e politiche neoliberiste dall’altro?Abstract – FRQui est Tsigane? Celui que je nomme Tsigane, que j'assigne à cette identité et que je constitue en "autre" du reste de la société. Dans ce sens, l'histoire des Tsiganes se confond avec celle de l'"antitsiganisme", un néologisme qui recouvre une pratique ancienne. Mais peut-on dire que l'apparition de ce nouveau mot estliée aux croisements actuels entre les politiques multiculturelles d'une part, et les politiques néolibéralesde l'autre? Abstract – EN Who is Gypsy? The person I call Gypsy, to whom I assign this identity, is that I establish as "other" than the rest of society. In this sense, the history of Gypsies merges with that of "antigypsism", a neologism that denotes an ancient practice. But can it be said that the appearance ofthis new word is linked to the current entanglement between multi-cultural politics on one side and neo-liberalist politics on the other?

  9. Il piu grande centro europeo di ricerca oggi festeggia l'anniversario del Nobel di Rubbia e Van der Meer. Cern, vent'anni guardando al futuro Ora la sfida si gioca sull'acceleratore di particelle pronto per il 2007, che provera a svelare i segreti della materia

    CERN Multimedia

    Durante, E

    2003-01-01

    "CERN, vent'anni guardando al futuro Ora la sfida si gioca sull'acceleratore di particelle pronto per il 2007, che provera a svelare i segreti della materia" [CERN, twenty years of looking towards the future. The present challenge is the particle accelerator that will be ready in 2007, which will try to reveal the secrets of matter] (2 pages)

  10. Perché io credo in colui che ha fatto il mondo

    CERN Document Server

    Zichichi, Antonino

    1999-01-01

    Fin troppo spesso si sente dire che il mondo della scienza e quello della religione sono in completa opposizione e che non condividono alcuna esperienza o caratteristica in comune. Nulla potrebbe essere più falso di queste affermazioni secondo Antonino Zichichi, che in quest'opera afferma come la ricerca scientifica e l'esperienza religiosa abbiano in comune molto più di quanto si possa pensare.

  11. Altruisti, cooperativi e morali: Perché è più facile esserlo domani che oggi

    NARCIS (Netherlands)

    Giacomantonio, M.; de Dreu, C.K.W.

    2013-01-01

    Un portafogli smarrito e ritrovato. Una donazione ad un ente che si occupa di ricerca sulle malattie degenerative. Una tangente non accettata. Un divorzio che si conclude senza il ricorso al tribunale. Alla base di tutti questi eventi vi è la tendenza umana a cooperare, ad essere altruisti e ad

  12. Che-1 gene silencing induces osteosarcoma cell apoptosis by inhibiting mutant p53 expression

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ming; Wang, Dan, E-mail: danwangwdd@163.com; Li, Ning

    2016-04-22

    The transcriptional cofactor Che-1 is an RNA polymerase II (Pol II) which is involved in tumorigenesis, such as breast cancer and multiple myeloma. Che-1 can also regulate mutant p53 expression, which plays roles in many types of cancer. In this study, we aimed to investigate the effects and specific mechanism of Che-1 in the regulation of osteosarcoma (OS) cell growth. We found that Che-1 is highly expressed in several kinds of OS cells compared with osteoblast hFOB1.19 cells. MTT and flow cytometry assays showed that Che-1 depletion by siRNA markedly suppressed MG-63 and U2OS cell proliferation and promoted apoptosis. The chromatin immunoprecipitation (ChIP) assay verified the presence of Che-1 on the p53 promoter in MG-63 and U2OS cells carrying mutant p53. Further studies showed that Che-1 depletion inhibited mutant p53 expression. Notably, our study showed that the loss of Che-1 inhibits proliferation and promotes apoptosis in MG-63 cells by decreasing the level of mutant p53. Therefore, these findings open the possibility that silencing of Che-1 will have therapeutic benefit in OS. - Highlights: • Che-1 is highly expressed in several kinds of OS cells. • Che-1 depletion suppressed MG-63 and U2OS cell growth. • Che-1 is existed in the p53 promoter in MG-63 and U2OS cells. • Che-1 depletion inhibited mutant p53 expression. • Che-1 depletion inhibits cell growth by decreasing the level of mutant p53.

  13. Che: His Own Worst Enemy

    Science.gov (United States)

    2015-04-01

    comprised of Green Berets, to go to Bolivia and train a Ranger battalion 40 in counter-insurgency operations. Leading this 16-man team was Maj...York: Routledge & Kegan Ltd., 1987. Sinclair, Andrew. Che Guevara. New York: The Viking Press, 1970. Study of the “Diary of ‘Che’ Guevara in

  14. La Pubblica Amministrazione in uno scenario che cambia

    Directory of Open Access Journals (Sweden)

    Renzo Carlucci

    2009-03-01

    Full Text Available Questo numero, mirato alle implicazioni dell'utilizzo del dato territoriale nel contesto delle PA, le Pubbliche Amministrazioni, si arricchisce di un contenuto ulteriore, particolarmente spaziale; GEOmedia esce infatti in coincidenza con una manifestazione che possiamo considerare la vetrina mediterranea privilegiata per la promozione culturale, scientifica e commerciale delle istituzioni e del segmento dell’industria aerospaziale europea ed italiana.

  15. Cholinesterase (ChE) response and related mortality among birds fed ChE inhibitors

    Science.gov (United States)

    Ludke, J.L.; Hill, E.F.; Dieter, M.P.

    1975-01-01

    Patterns of mortality and inhibition of brain and plasma ChE in birds treated with ChE inhibitors were studied in an attempt to determine the validity of using ChE activity as a monitoring and diagnostic technique. Analysis of brain ChE activity proved to be reliable for diagnosing and monitoring effects of selected ChE inhibitors in birds. Brain ChE inhibition exceeding 20% indicated exposure, and inhibition greater than 50% was sufficient for diagnosing cause of death. Individuals that died from dietary exposure to parathion or carbofuran had brain ChE activities below 55% of normal; although individuals could survive with brain ChE activity lower than 50%. Problems associated with collection, storage, and analysis of tissues for ChE activity are discussed.

  16. Introduzione. Donne che portano la parrucca

    Directory of Open Access Journals (Sweden)

    Claudia Mattalucci-Yılmaz

    2013-07-01

    Full Text Available Peruk takan kadınlar è l’opera che nel 1999 l’artista e cineasta turco Kutlug Ataman ha presentato alla Biennale di Venezia curata da Harald Szeemann. Quattro schermi giustapposti proiettano le testimonianze di donne che, per un periodo della loro vita, hanno portato una parrucca: un’attivista politica di sinistra che nel 1971, dopo il colpo di stato militare, utilizzava un nome in codice, una divisa delle Turkish Airlines e una parrucca per sfuggire al controllo della polizia; una giornalista, colpita da un tumore al seno, che ha portato una parrucca per mascherare gli effetti della chemioterapia; una studentessa musulmana che indossa una parrucca per frequentare l’università, in un contesto – quello turco – che in nome della laicità dello Stato, interdice l’uso nel foulard nelle scuole, nelle università e nella pubblica amministrazione; e infine un transessuale.

  17. I sei numeri dell'universo le forze profonde che spiegano il cosmo

    CERN Document Server

    Rees, Martin

    2002-01-01

    È possibile che sei semplici numeri, sei costanti universali, diano conto dell'infinita varietà e della stupefacente complessità del cosmo? L'astrofisico Martin Rees ci mostra che non soltano ciò è possibile, ma in quei sei numeri sono scritti la storia, la struttura e il futuro dell'universo, e che perfino la comparsa della vita sulla terra, e dunque la nostra stessa esistenza, non sarebbe concepibile se uno solo di quei valori numerici, definiti nell'istante che segnò la nascita del mondo, fosse differente. I sei numeri dell'universo ci introducono così ad alcune delle questioni più profonde su cui si interroga oggi la scienza.

  18. Il fantasma dell'universo che cos'è il neutrino

    CERN Document Server

    Votano, Lucia

    2015-01-01

    Ben prima della luce, a un decimillesimo di secondo dal Big Bang, i neutrini sono apparsi nell'universo. Dopo un secondo il brodo primordiale si era raffreddato abbastanza da consentire loro di muoversi liberi e ancora oggi, dopo quasi quattordici miliardi di anni, sono numerosissimi. Ma che cosa sono i neutrini? Elusivi come fantasmi, camaleontici, viaggiano indenni attraverso la materia arrivando dritti sino a noi dagli angoli più remoti e nascosti dell'universo. Per saperne di più seguiremo i fisici che li studiano in laboratori sotterranei o in luoghi estremi come i ghiacciai polari o le profondità marine.

  19. Dicty_cDB: CHE636 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available CH (Link to library) CHE636 (Link to dictyBase) - - - Contig-U11696-1 CHE636P (Link... to Original site) CHE636F 174 CHE636Z 123 CHE636P 277 - - Show CHE636 Library CH (Link to library) Clone ID CHE636 (Link to dict...yBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U11696-1 Original site URL http://dict...ne RP11-15H22, WORKING DRAFT SEQUENCE, 23 unordered pieces. 40 0.19 3 AC149612 |AC149612.1 Ictalurus punctat... %: cytoskeletal 4.0 %: mitochondrial >> prediction for CHE636 is nuc 5' end seq. ID CHE636F 5' end seq. >CH

  20. Structural Insight inot the low Affinity Between Thermotoga maritima CheA and CheB Compared to their Escherichia coli/Salmonella typhimurium Counterparts

    Energy Technology Data Exchange (ETDEWEB)

    S Park; B Crane

    2011-12-31

    CheA-mediated CheB phosphorylation and the subsequent CheB-mediated demethylation of the chemoreceptors are important steps required for the bacterial chemotactic adaptation response. Although Escherichia coli CheB has been reported to interact with CheA competitively against CheY, we have observed that Thermotoga maritima CheB has no detectable CheA-binding. By determining the CheY-like domain crystal structure of T. maritima CheB, and comparing against the T. maritima CheY and Salmonella typhimurium CheB structures, we propose that the two consecutive glutamates in the {beta}4/{alpha}4 loop of T. maritima CheB that is absent in T. maritima CheY and in E. coli/S. typhimurium CheB may be one factor contributing to the low CheA affinity.

  1. Crèche and School

    CERN Multimedia

    EVE et École

    2018-01-01

    IMPORTANT DATES Enrolments 2018-2019 Enrolments to the Crèche and School for the school year 2018-2019 will take place on 5, 6 and 7 March 2018 from 10 am to 1 pm at the Crèche and School of the CERN Staff Association. Registration forms will be available from Thursday 1st March 2018. For more information, please visit the website: http://nurseryschool.web.cern.ch/. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Saturday 3 March 2018 Open Day at Crèche and School of the CERN Staff Association Are you considering enrolling your child to the Crèche and School of the CERN Staff Association? If you work at CERN, then this event is for you: come visit the school and meet the Management on Saturday 3 March 2018 from 10 to 12 am It will be our pleasure to present to you our structure, its projects and premises, and answer any questions you may have. Please sign up for one of the two sessions via Doodle before Wednesd...

  2. Il museo che non c’è. Note sulla dispersione del patrimonio in Gran Bretagna

    Directory of Open Access Journals (Sweden)

    Caroline Patey

    2011-03-01

    Full Text Available Indifferente alla loro recente moltiplicazione come al sodalizio che vi si celebra con l’architettura di grido, un fantasma si aggira per i musei. Sordo al nome di Jean Nouvel (Reina Sofia, Louvre quanto a quelli di Herzog & De Meuron (Tate Modern, impermeabile ai fasti del British Museum (Norman Foster come ai restauri della Tate Britain (James Stirling, disinteressato alle fortune del ‘nuovo’ Victoria and Albert Museum e malinconico come si addice alla sua natura, il fantasma invita a interrogare tanta luccicante spettacolarità e forse a non dimenticare che, per quanto custode di memoria e guardiano di culture, il museo è anche il luogo dove vengono consumate, direttamente o meno, amnesie e damnatio memoriae e in nome del quale continuano a perpetrarsi non poche violazioni e disseminazioni.

  3. Dicty_cDB: CHE687 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available CH (Link to library) CHE687 (Link to dictyBase) - - - Contig-U16336-1 - (Link to Or...iginal site) CHE687F 622 - - - - - - Show CHE687 Library CH (Link to library) Clone ID CHE687 (Link to dicty...Base) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U16336-1 Original site URL http://dictycdb.b...KFINQCINEIKEELKGDMQKKTVAVQKLTYIQ MLGFDISWASFKIVEVMSCNKFSSKRIGYLAASQSFNEGTDVIVLATHQIRKDFLSSNQS EAYLALNCLSNICT...LGFDISWASFKIVEVMSCNKFSSKRIGYLAASQSFNEGTDVIVLATHQIRKDFLSSNQS EAYLALNCLSNICTTDLARELANDILTLLSTQKTHILKRAITVLYKIF

  4. Che legend elab ka 40 aastat hiljem / Evelyn Kaldoja

    Index Scriptorium Estoniae

    Kaldoja, Evelyn, 1980-

    2007-01-01

    Ilmunud ka: Postimees : na russkom jazõke 9. okt. lk. 10. Argentinas sündinud ja 1967. aastal hukatud revolutsionääri Ernesto Che Guevara poliitikukarjäärist, tema panusest Kuuba revolutsiooni ja poliitikasse. Ernesto Che Guevara mälestamisest Ladina-Ameeerika riikides. Lisa: Kuuba revolutsioon; Che Guevara elu

  5. Una presenza che si fa ombra in Oriente

    OpenAIRE

    Giovanni Azzaroni

    2017-01-01

    In the contest of Asian culture the “shadow structure” is discussed connected to its native world and then it has to be interpreted starting to the culture of its original world. This essay investigates three different geographic situation, that is Japan (nōtheatre), China (shadow theatre) and Indonesia (shadow theatre), to connect as well as possible the vision and “shadow philosophy” to accurate and cultural perspectives, which can relate it to real cultural images.

  6. Una presenza che si fa ombra in Oriente

    Directory of Open Access Journals (Sweden)

    Giovanni Azzaroni

    2017-03-01

    Full Text Available In the contest of Asian culture the “shadow structure” is discussed connected to its native world and then it has to be interpreted starting to the culture of its original world. This essay investigates three different geographic situation, that is Japan (nōtheatre, China (shadow theatre and Indonesia (shadow theatre, to connect as well as possible the vision and “shadow philosophy” to accurate and cultural perspectives, which can relate it to real cultural images.

  7. La macchina che cerca Dio. Nasce LHC forse scoprira' Higgs elusiva particella della creazione

    CERN Multimedia

    Bianucci, P

    2003-01-01

    "LEON Lederman, premio Nobel per la fisica, l'ha misticamente definita la particella di Dio perche' sarebbe il pilastro sul quale si appoggia tutta la materia dell'universo che conosciamo. Piu' tecnicamente, e' la "particella di Higgs", un bosone previsto dal Modello Standard del microcosmo la cui esistenza sarebbe necessaria per giustificare, anche quantitativamente, la massa di tutte le particelle" (1/2 page).

  8. Inwentarz fary chełmińskiej i jej biblioteki z XV wieku

    Directory of Open Access Journals (Sweden)

    Mateusz Superczyński

    2017-07-01

    Full Text Available Artykuł niniejszy prezentuje edycję nieznanego szerzej dotychczas inwentarza fary chełmińskiej i wykazu księgozbioru biblioteki farnej z XV w., które znajdują się w księdze miejskiej Chełmna – kopiariuszu przywilejów i dokumentów, założonej przez pisarza Konrada Bitschina w 1431 r. Przekaz źródłowy daje obraz biblioteki fary chełmińskiej jako ośrodka kultury w XV-wiecznym Chełmnie. Pozwala także na porównanie trzech zachowanych spisów księgozbiorów średniowiecznego Chełmna, a więc z klasztoru Franciszkanów z XIII wieku, biblioteki farnej i zrekonstruowanego spisu biblioteki Braci Wspólnego Życia z końca XV stulecia, które pochodzą z różnych okresów i odzwierciedlają przemiany w duchowości, teologii i zainteresowaniach naukowych ówczesnych elit intelektualnych miasta. Podczas gdy księgozbiory biblioteki franciszkanów czy farnej oddają ducha średniowiecznej scholastyki czy nominalizmu, to wydania, które posiadali Bracia Wspólnego Życia, zwiastują nadejście humanizmu. Odnotowane przez pisarza miejskiego tytuły, mimo zniekształceń,pozwalają także na identyfikację i odnalezienie wśród nich fundamentalnych dla średniowiecznej teologii, liturgii, historii i filozofii dzieł.

  9. La nascita imperfetta delle cose la grande corsa alla particella di Dio e la nuova fisica che cambierà il mondo

    CERN Document Server

    AUTHOR|(CDS)2068901

    2016-01-01

    In quel preciso momento, un centesimo di miliardesimo di secondo dopo il Big Bang, si è deciso il nostro destino. In un universo in cui materia e antimateria si equivalevano, e che quindi avrebbe potuto, in ogni istante, tornare a essere pura energia, può essere bastata una leggerissima preferenza del bosone di Higgs per la materia anziché per l'antimateria ed ecco che si è prodotto il mondo che abbiamo sotto gli occhi. "Ecco qua il minuscolo difetto, la sottile imperfezione da cui è nato tutto. Un'anomalia che dà origine a un universo che può evolvere per miliardi di anni." Se tutto nasce da lì, dobbiamo capire in ogni dettaglio quel momento cruciale, ricostruirlo fotogramma per fotogramma, al rallentatore e da diverse angolature. Per questo al Cern di Ginevra è stato realizzato Lhc, l'acceleratore di particelle più potente del mondo, il posto più simile al primo istante di vita dell'universo che l'uomo sia stato in grado di costruire. Per questo da anni i migliori fisici del mondo lavorano giorno...

  10. Sulle ipotesi che stanno alla base della geometria e altri scritti scientifici e filosofici

    CERN Document Server

    Riemann, Bernhard

    1994-01-01

    Il volume raccoglie, oltre al testo della lezione del 1854 che dà il titolo all'opera, alcuni scritti di carattere scientifico e filosofico di Riemann. A saggi di argomento scientifico si affiancano scritti di argomento più direttamente metodologico. La concezione della scienza che ci viene offerta da questi scritti è assai significativa del personaggio e della sua epoca. Per Riemann la matematica non è un mero strumento esteriore da applicare, appunto dall'esterno, ai fenomeni. Al contrario, essa consente di spingersi con il rigore necessario oltre alla superficie dei fenomeni e di penetrare sempre più a fondo nella realtà, nell'ottica di un sistema unitario e quasi metafisico del sapere scientifico.

  11. Fractional derivatives. An introduction; Derivate frazionarie. Che cosa sono, a cosa servono

    Energy Technology Data Exchange (ETDEWEB)

    Dattoli, G. [ENEA, Div. Fisica Applicata, Centro Ricerche Frascati, Rome (Italy)

    2001-07-01

    In this item is presented a brief survey of fractional calculus and of the relevant applications. In the work are discussed different points of view of the operation of fractional derivative and present a unifying definition. The role played by fractional derivatives and integrals within the framework of integral transform is analyzed. [Italian] In questo articolo si traccia un profilo del cosidetto calcolo frazionario e delle relative applicazioni a problemi di matematica pura ed applicata. Si discutono varie definizioni dell'operazione di derivata frazionaria, non tutte coincidenti fra loro, e si mostra come sia possibile proporre una definizione univoca che inglobi tutte le altre. Si analizza infine il ruolo giocato dalle derivate e dagli integrali frazionari e, piu' in generale, quello degli operatori differenziali ad esponente frazionario, nell'ambito della teoria delle rappresentazioni integrali.

  12. l'italiano che cambia: apocalisse o palingenesi? alcune riflessioni ...

    African Journals Online (AJOL)

    User

    idea that a real linguistic apocalypse is to be found on one hand, in what. Calvino ... nell'italiano contemporaneo da una prospettiva che, audacemente, definiamo ...... 'terrore semantico', cioè la fuga di fronte a ogni vocabolo che abbia di.

  13. LA LINGUA FILMATA: "L'UOMO CHE VERRÀ" DI GIORGIO DIRITTI

    Directory of Open Access Journals (Sweden)

    Marta Idini

    2016-02-01

    Full Text Available La lingua filmata appare oggi uno dei campi linguistici in cui il dialetto torna ad essere scelta registica e veicolo di nuove istanze comunicative, in stretta relazione con un nuovo modo di intendere e praticare il cinema. Il presente articolo introduce il lettore alla consuetudine cinematografica del dialetto, analizzandone la presenza e le funzioni che gli sono state attribuite nei decenni trascorsi e presenti, e guarda a L’Uomo che verrà quale espressione attuale di una nuova risorgenza dialettale all’interno delle pellicole nostrane. Attraverso un’analisi attenta dei fenomeni vernacolari in esso presenti, l’indagine si sofferma sulle motivazioni e l’efficacia comunicativa cui perviene l’uso del dialetto e si interroga su quale grado di realismo o mimesi linguistica Diritti abbia raggiunto. Language of film: "L’uomo che verrà" by Giorgio DirittiLanguage in films is one of the fields where dialect becomes a choice and a vehicle for new communicative demands, closely related the new way of understanding and practicing the cinema. This article introduces the reader to the use of dialect in films, analyzing the presence and functions that have been attributed to it in the past and present decades, and looks at L’Uomo che verrà as an expression of the new resurgence of dialect in Italian films. Through careful analysis of the vernacular, the paper focuses on the motivations and the communicative effectiveness of the use of dialect and questions the degree of realism or linguistic mimesis that Diritti was able to reach.

  14. Natural gas prices in Italy. Tariffs geographical distribution; Metano. Paese che vai, prezzo che trovi

    Energy Technology Data Exchange (ETDEWEB)

    Marrocchelli, A. [ENEA, Rome (Italy). Centro Ricerche Casaccia

    2000-11-01

    The annual report on services and activity carries at some evaluations of data concerned the natural gas market: total consumption, costs and prices in Italy and comparative evaluations with other european countries. [Italian] La relazione annuale sullo stato dei servizi e sull'attivita' svolta, presentata dal Presidente dell'Autorita' per l'energia elettrica e il gas, porta ad alcune considerazioni sui dati che riguardano il mercato del gas naturale: i consumi totali, i costi e i prezzi in Italia, il confronto con i costi e i prezzi praticati negli altri paesi europei.

  15. CheMentor Software System by H. A. Peoples

    Science.gov (United States)

    Reid, Brian P.

    1997-09-01

    CheMentor Software System H. A. Peoples. Computerized Learning Enhancements: http://www.ecis.com/~clehap; email: clehap@ecis.com; 1996 - 1997. CheMentor is a series of software packages for introductory-level chemistry, which includes Practice Items (I), Stoichiometry (I), Calculating Chemical Formulae, and the CheMentor Toolkit. The first three packages provide practice problems for students and various types of help to solve them; the Toolkit includes "calculators" for determining chemical quantities as well as the Practice Items (I) set of problems. The set of software packages is designed so that each individual product acts as a module of a common CheMentor program. As the name CheMentor implies, the software is designed as a "mentor" for students learning introductory chemistry concepts and problems. The typical use of the software would be by individual students (or perhaps small groups) as an adjunct to lectures. CheMentor is a HyperCard application and the modules are HyperCard stacks. The requirements to run the packages include a Macintosh computer with at least 1 MB of RAM, a hard drive with several MB of available space depending upon the packages selected (10 MB were required for all the packages reviewed here), and the Mac operating system 6.0.5 or later.

  16. L'evoluzione del WEB GIS la filiera postgis-mapserver-geoext- openlayers per sviluppare piattaforme GIS complete, agili ed economiche

    Directory of Open Access Journals (Sweden)

    Francesco Mariucci

    2012-04-01

    Full Text Available Spesso, nel nostro ambito, ci si sente dire che il GIS è un bene di lusso, dal quale, soprattutto in epoca di crisi economica, le piccole entità (sia in ambito pubblico che privato possono facilmente prescindere. Questo articolo vuole segnalare la presenzadi tecnologie non nuove ma consolidate che unite insieme possono costituire una base informatica flessibile e di costi ridotti per l'implementazione di piattaforme GIS dedicate che siano di supporto anche per le piccole realtà nella gestione di dati ed attività territoriali, con notevoli vantaggi sulla produttività e sull'immagine

  17. Zur chemie der marsoberfläche

    Science.gov (United States)

    Keil, Klaus; Clark, Benton C.; Baird, A.K.; Toulmin, Priestley; Rose, Harry J.

    1978-01-01

    Analyses of 13 samples of Martian surface materials with the Viking X-ray fluorescence spectrometers show SiO2 similar to that of terrestrial mafic rocks, whereas Fe2O3, Cl, and S are higher and Al2O3, K2O, Rb, Sr, Y, and Zr are lower. Low totals suggest presence of CO2, H2O, and Na2O. Duricrust fragments are higher in S than fines, but samples from both landing sites are surprisingly similar. We suggest that Martian surface materials are aeolian deposits of complex mixtures of weathering products of maficultramafic rocks, possibly consisting of iron-rich clays, sulfates, iron oxides, carbonates, and chlorides.

  18. A crèche on the Meyrin CERN site

    CERN Multimedia

    Association du personnel

    2013-01-01

    A few months ago (see Echo 175) we announced the opening, at the end of August, of a crèche at the CERN Staff Association’s nursery school. After a very active summer, where a new floor was added to the canteen building, the new school year started in excellent conditions and, as expected, the new crèche opened on Tuesday 27 August. This crèche, with 13 full-time equivalent places, can accept 18 children aged between three months and two years in a space fully refitted to care for the little ones. A specially designed space for breastfeeding helps mothers working on the site to respect their baby's rhythm. In compliance with the standards of supervision in the canton of Geneva six educators take care of the children in shifts. This new space is fully integrated in the nursery school so that now the crèche, Kindergarten and school of the CERN Staff Association can welcome children aged from three months to six years, from Monday to Friday, and...

  19. à l'encoche sèche

    African Journals Online (AJOL)

    Chez Hevea brasiliensis, la production de latex est affectée par l'encoche sèche qui se manifeste par l'arrêt de l'écoulement de ... coagulation pour donner le caoutchouc naturel. ..... relationship between latex sugar content, the metabolic ...

  20. Crèche and School - Important dates

    CERN Multimedia

    Staff Association

    2018-01-01

    Enrolments 2018-2019 Enrolments to the Crèche and School for the school year 2018-2019 will take place on 5, 6 and 7 March 2018 from 10 am to 1 pm at the Crèche and School of the CERN Staff Association. Registration forms will be available from Thursday 1st March 2018. For more information, please visit the website: http://nurseryschool.web.cern.ch/. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Saturday 3 March 2018 Open Day at Crèche and School of the CERN Staff Association Are you considering enrolling your child to the Crèche and School of the CERN Staff Association? If you work at CERN, then this event is for you: come visit the school and meet the Management on Saturday 3 March 2018 from 10 to 12 am It will be our pleasure to present to you our structure, its projects and premises, and answer any questions you may have. Please sign up for one of the two sessions via Doodle before Friday 2 March 2018: htt...

  1. Che cos'è la vita ?, Scienza e umanesimo

    CERN Document Server

    Schrödinger, Erwin

    1988-01-01

    A cento anni dalla nascita di Erwin Schrödinger (Viena 1887), il suo pensiero e il suo lavoro mantengono inalterati la loro attualità, come dimostra la nuova pubblicazione di molti dei suoi testi e i numerosi convegni che gli vengono dedicati.

  2. Care and education in the Danish Créche

    DEFF Research Database (Denmark)

    Broström, Stig; Hansen, Ole Henrik

    2010-01-01

    This article seeks to identify the relation between policy and lived life, for the small child in the Danish crèche. To accomplish this, the article integrates demography, traditions, national curriculum and psychological, educational, and recent developments in research. It is an attempt to reveal...... research articles. It is used in the exploration of meanings of political, social, and cultural phenomena as experienced by the involved individuals themselves, in their natural context. It is a presumption that the child’s development is a consequence of emotional and cognitive stimulation. To outline...... that, it is vital to emphasize the influence that policy causes on educational practice in the crèche, e.g., the conceptualization of education and care....

  3. Ragioni e vantaggi del classificare la musica

    Directory of Open Access Journals (Sweden)

    Filippo Focosi

    2012-05-01

    Full Text Available The contemporary music scene, imbued with stylistic contaminations, is dominated by the idea that the differentiation between musical genres no longer makes sense: the only legitimate distinction should be between good and bad music. Yet, the so mistreated labels that separate classical music from jazz and pop are still in use, both in critical discourse and in the organization of musical life, individual and collective. In the attempt to solve this apparent paradox, which closely resembles the paradox of taste that animated the philosophical debate in Britain in the eighteenth century, the essay points out the advantages (as well as the limitations inherent to the genre conventions, also relating them to postmodern musical culture.

  4. Crystallization and preliminary X-ray crystallographic analysis of Thermotoga maritima CheA P3-P4-P5 domains in complex with CheW

    International Nuclear Information System (INIS)

    Park, SangYoun; Kim, Keon Young; Kim, Sunmin; Crane, Brian R.

    2012-01-01

    T. maritima CheA P3-P4-P5 domains were crystallized in complex with CheW. Low-resolution diffraction data were collected to ∼8 Å using synchrotron X-ray radiation. The CheA–CheW complex plays a key role in bacterial chemotaxis signal transduction by initiating phosphotransfer to response regulators via coupling to the chemoreceptors. CheA (P3-P4-P5 domains) and CheW from Thermotoga maritima were overexpressed in Escherichia coli and crystallized as a complex at 298 K using ammonium dihydrogen phosphate as a precipitant. X-ray diffraction data were collected to ∼8 Å resolution at 100 K using synchrotron radiation. The crystal belonged to space group I222 or I2 1 2 1 2 1 , with unit-cell parameters a = 184.2, b = 286.4, c = 327.7 Å. The asymmetric unit may contain six to ten CheA–CheW molecules

  5. Crystallization and preliminary X-ray crystallographic analysis of CheW from Thermotoga maritima: a coupling protein of CheA and the chemotaxis receptor

    International Nuclear Information System (INIS)

    Park, SangYoun; Crane, Brian R.

    2011-01-01

    CheW from T. maritima has been crystallized (space group P6 3 , unit-cell parameters a = b = 61.265, c = 361.045 Å). Diffraction data have been collected to 3.1 Å resolution using synchrotron X-ray radiation. The CheW protein plays a key role in bacterial chemotaxis signal transduction by coupling CheA to chemotaxis receptors. CheW from Thermotoga maritima has been overexpressed in Escherichia coli and crystallized at 298 K using ammonium sulfate as a salt precipitant. X-ray diffraction data have been collected to 3.10 Å resolution at 100 K using synchrotron radiation. The crystal belonged to space group P6 3 , with unit-cell parameters a = b = 61.265, c = 361.045 Å. The asymmetric unit may contain four to six CheW molecules

  6. Data from the Mars Science Laboratory CheMin XRD/XRF Instrument

    Science.gov (United States)

    Vaniman, David; Blake, David; Bristow, Tom; DesMarais, David; Achilles, Cherie; Anderson, Robert; Crips, Joy; Morookian, John Michael; Spanovich, Nicole; Vasavada, Ashwin; hide

    2013-01-01

    The CheMin instrument on the Mars Science Laboratory (MSL) rover Curiosity uses a Co tube source and a CCD detector to acquire mineralogy from diffracted primary X-rays and chemical information from fluoresced X-rays. CheMin has been operating at the MSL Gale Crater field site since August 5, 2012 and has provided the first X-ray diffraction (XRD) analyses in situ on a body beyond Earth. Data from the first sample collected, the Rocknest eolian soil, identify a basaltic mineral suite, predominantly plagioclase (approx.An50), forsteritic olivine (approx.Fo58), augite and pigeonite, consistent with expectation that detrital grains on Mars would reflect widespread basaltic sources. Minor phases (each XRD. This amorphous component is attested to by a broad rise in background centered at approx.27deg 2(theta) (Co K(alpha)) and may include volcanic glass, impact glass, and poorly crystalline phases including iron oxyhydroxides; a rise at lower 2(theta) may indicate allophane or hisingerite. Constraints from phase chemistry of the crystalline components, compared with a Rocknest bulk composition from the APXS instrument on Curiosity, indicate that in sum the amorphous or poorly crystalline components are relatively Si, Al, Mg-poor and enriched in Ti, Cr, Fe, K, P, S, and Cl. All of the identified crystalline phases are volatile-free; H2O, SO2 and CO2 volatile releases from a split of this sample analyzed by the SAM instrument on Curiosity are associated with the amorphous or poorly ordered materials. The Rocknest eolian soil may be a mixture of local detritus, mostly crystalline, with a regional or global set of dominantly amorphous or poorly ordered components. The Rocknest sample was targeted by MSL for "first time analysis" to demonstrate that a loose deposit could be scooped, sieved to <150 microns, and delivered to instruments in the body of the rover. A drilled sample of sediment in outcrop is anticipated. At the time of writing this abstract, promising outcrops are

  7. Il mondo secondo la fisica quantistica segreti e meraviglie della scienza che sta cambiando la nostra vita

    CERN Document Server

    Fracas, Fabio

    2017-01-01

    Questo libro è un'avventura esclusiva e affascinante. Un viaggio, anche nel tempo, alla scoperta di qualcosa di nuovo e di straordinario: la Fisica Quantistica, nelle sue logiche, nelle sue potenzialità, nelle sue applicazioni e nei suoi possibili sviluppi. All'interno del volume vengono ricostruiti passo dopo passo i momenti fondamentali del pensiero quantistico, le questioni su cui si sono interrogati i più grandi scienziati degli ultimi decenni, e i diversi contesti nei quali si sono evoluti i principali modelli della Meccanica Quantistica. Sullo sfondo delle ricerche più attuali - come per esempio quella sulle onde gravitazionali che ha portato al Nobel per la Fisica 2017 -, vengono indagati anche i rapporti esistenti fra Fisica Quantistica, Relatività Einsteiniana e Teoria delle Stringhe. Inoltre, fra i tanti temi trattati nelle sue pagine, trovano spazio persino le incredibili ricadute che gli studi sulla Fisica Quantistica stanno avendo negli ambiti della medicina e delle ricerche sul cervello e s...

  8. Finally, a crèche at CERN!

    CERN Multimedia

    Anaïs Schaeffer

    2013-01-01

    After many years of discussion, the CERN Staff Association’s first crèche will open its doors in September to welcome up to 20 babies and toddlers.   A delicate operation: the installation of 11 modules above the Nursery's School canteen. Image: Sigrid Knoops. The CERN Staff Association’s Nursery School, which will soon turn 50, is pleased to announce the establishment of CERN’s first crèche. This project, which has come to fruition over the past academic year with the support of the CERN Management, meets an established and growing need among the Laboratory’s personnel and users. As a modular construction, the Nursery School’s new second floor was assembled above the existing canteen in a matter of days. Its 11 modules are ultra-modern – they’re even equipped with underfloor heating. “Thanks to this extension, we will be able to accept around twenty babies at the start of the academ...

  9. Heterozygous Che-1 KO mice show deficiencies in object recognition memory persistence.

    Science.gov (United States)

    Zalcman, Gisela; Corbi, Nicoletta; Di Certo, Maria Grazia; Mattei, Elisabetta; Federman, Noel; Romano, Arturo

    2016-10-06

    Transcriptional regulation is a key process in the formation of long-term memories. Che-1 is a protein involved in the regulation of gene transcription that has recently been proved to bind the transcription factor NF-κB, which is known to be involved in many memory-related molecular events. This evidence prompted us to investigate the putative role of Che-1 in memory processes. For this study we newly generated a line of Che-1(+/-) heterozygous mice. Che-1 homozygous KO mouse is lethal during development, but Che-1(+/-) heterozygous mouse is normal in its general anatomical and physiological characteristics. We analyzed the behavioral characteristic and memory performance of Che-1(+/-) mice in two NF-κB dependent types of memory. We found that Che-1(+/-) mice show similar locomotor activity and thigmotactic behavior than wild type (WT) mice in an open field. In a similar way, no differences were found in anxiety-like behavior between Che-1(+/-) and WT mice in an elevated plus maze as well as in fear response in a contextual fear conditioning (CFC) and object exploration in a novel object recognition (NOR) task. No differences were found between WT and Che-1(+/-) mice performance in CFC training and when tested at 24h or 7days after training. Similar performance was found between groups in NOR task, both in training and 24h testing performance. However, we found that object recognition memory persistence at 7days was impaired in Che-1(+/-) heterozygous mice. This is the first evidence showing that Che-1 is involved in memory processes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  10. Rachunek dochodów i wydatków budżetu jednostki samorządu terytorialnego na przykładzie gminy Chełmiec w latach 2011-2013

    OpenAIRE

    Rodak, Anna

    2015-01-01

    Przedłożona praca ma na celu wskazanie źródeł i struktury dochodów budżetowych oraz charakteru wydatkowania środków budżetowych gminy Chełmiec, a także dokonanie rzetelnej oceny sytuacji finansowej wymienionej powyżej jednostki. Analiza budżetu obejmuje zakres czasowy od 2011 do 2013 roku. Szczegółowe pytania, na które starano się w niniejszej pracy odpowiedzieć są następujące: Czy gmina Chełmiec jest gospodarna w wykorzystywaniu środków budżetowych? oraz jak gmina Chełmiec mając do dyspozycj...

  11. Discovering Che-1/AATF: a new attractive target for cancer therapy

    Directory of Open Access Journals (Sweden)

    Simona eIezzi

    2015-04-01

    Full Text Available The transcriptional cofactor Che-1/AATF is currently emerging as an important component of the DNA damage response machinery, the complex signaling network that maintains genome integrity and prevents tumorigenesis. Moreover this protein is involved in a wide range of cellular pathways, regulating proliferation and survival in both physiological and pathological conditions. Notably, some evidence indicates that dysregulation of Che-1/AATF levels are associated with the transformation process and elevated levels of Che-1/AATF are required for tumor cell survival. It is for these reasons that Che-1/AATF has been regarded as an attractive, still theoretical, therapeutic target for cancer treatments. In this review, we will provide an updated overview of Che-1/AATF activities, from transcriptional regulation to DNA damage response.

  12. His Excellency Professor Dr Che-Ho Wei, Chairman, National Science Council Executive Yuan, Republic of China

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    Photo 01: Professor Dr. Che-Ho Wei signing the Guest Book with CERN Director-General, L. Maiani. Photo 02: Professor Dr. Che-Ho Wei. Photo 03::Professor Dr. Che-Ho Wei shaking hands with CERN Director-General, L. Maiani.

  13. Il mito della precarietà: quando la precarietà è un valore che decostruisce l’immaginario della precarietà

    Directory of Open Access Journals (Sweden)

    Antonio Casillo

    2011-07-01

    Full Text Available Oggi la ricerca del posto “fisso” sembra essere il sogno irraggiungibile di molti giovani precari e la “flessibilità”, una parola d’ordine con cui si aspirava a riformare il mondo del lavoro e che tanto in voga sembrava essere negli anni ’90, è diventata sinonimo di incertezza, precarietà, se non addirittura sfruttamento. Ma c’era chi proprio nel lavoro che oggi definiremo precario, vedeva l’unica possibilità per restare libero dalle leggi di mercato e dai potenti poteri editoriali Newyorkesi. In questo articolo proviamo a gettare uno sguardo al mito letterario con cui, il rifiutare un posto fisso, significava rivendicare la propria libertà, un mito romantico certo, e sicuramente distante dalla realtà, ma che ha affascinato un’intera generazione di scrittori, poeti, musicisti. Da Jack London, passando attraverso la San Francisco Renaissance e la Beat Generation, fino ad arrivare al fenomeno della così detta generazione Hippy, il sogno americano sembrava essere quello di una frontiera mobile in cui, la strada, sembrava non avere mai fine.

  14. Los marcadores che y boludo: ¿un caso de rivalidad conversacional?

    Directory of Open Access Journals (Sweden)

    Markéta Šmídová

    2016-11-01

    Full Text Available It has been recently suggested that the Argentinian conversational marker che is being replaced by another typical expression, boludo. The purpose of the present paper is to provide a pilot comparative study of these two Argentinian markers in order to examine their free interchangeability and to refute it eventually. A commutation test has been used as a basic tool to compare the behavior and functions of che and boludo and the results have helped to reveal contexts in which it would be inadmissible or inappropriate to employ boludo instead of che due to the possible violation of politeness norms. In the article, che and boludo are considered mainly from the sociolinguistic and pragmatic approaches although some important cultural phenomena are discussed as well.

  15. Award ceremony for the "Crèche and School" competition

    CERN Multimedia

    Staff Association

    2018-01-01

    Whenever there is a competition, there are obviously participants – and especially winners! The awards ceremony for the competition to find a new name for the CERN Staff Association's Crèche and School took place on 15 May. During the ceremony, jointly led by Céline Grobon (President of the Crèche and School Steering Committee), Carole Dargagnon (Headmistress of the Crèche and School) and Jean-Baptiste Zenner (Staff Association delegate), the proposals selected by the jury were rewarded. The first place went to Marie-Luz Cavagna for her proposal "Le jardin des petits chercheurs", and the second place to Sarah Palluel for her proposal "Le Jardin des Zélectrons". Finally, Aude Mourey and Sandra Fleury tied for third place with their respective proposals "Les petits atomes" and "La crèche des particules". Can we find the winning name of the competition among...

  16. MSL Chemistry and Mineralogy X-Ray Diffraction X-Ray Fluorescence (CheMin) Instrument

    Science.gov (United States)

    Zimmerman, Wayne; Blake, Dave; Harris, William; Morookian, John Michael; Randall, Dave; Reder, Leonard J.; Sarrazin, Phillipe

    2013-01-01

    This paper provides an overview of the Mars Science Laboratory (MSL) Chemistry and Mineralogy Xray Diffraction (XRD), X-ray Fluorescence (XRF) (CheMin) Instrument, an element of the landed Curiosity rover payload, which landed on Mars in August of 2012. The scientific goal of the MSL mission is to explore and quantitatively assess regions in Gale Crater as a potential habitat for life - past or present. The CheMin instrument will receive Martian rock and soil samples from the MSL Sample Acquisition/Sample Processing and Handling (SA/SPaH) system, and process it utilizing X-Ray spectroscopy methods to determine mineral composition. The Chemin instrument will analyze Martian soil and rocks to enable scientists to investigate geophysical processes occurring on Mars. The CheMin science objectives and proposed surface operations are described along with the CheMin hardware with an emphasis on the system engineering challenges associated with developing such a complex instrument.

  17. Che cos'è la conoscenza? un universo in espansione

    CERN Document Server

    Franceschini, Guiliano

    2017-01-01

    Il testo propone un viaggio nell'universo della conoscenza, tra le galassie di conoscenza (religione, scienza, arte), nel cervello (percezione, apprendimento, memoria) e nell'etica (dalla conoscenza all'educazione). Le argomentazioni si espandono attraverso un registro comunicativo intuitivo, tra divulgazione e speculazione, attraverso esempi e riferimenti concreti, rivolgendosi in alcuni casi direttamente al lettore.

  18. Che a 1: recombinant expression, purification and correspondence to the natural form.

    Science.gov (United States)

    Barderas, Rodrigo; Villalba, Mayte; Rodríguez, Rosalía

    2004-12-01

    Pollinosis to chenopods is one of the main causes of allergy in desertic regions and it is increasing in the South of Europe and Western USA. Che a 1 is a major allergen for chenopod-allergic subjects and belongs to the Ole-e-1-like family of proteins. Pichia pastoris yeast has been used as expression system to produce the recombinant form of Che a 1 (rChe a 1). The allergen was isolated using a gel permeation column and reverse-phase/high-performance liquid chromatography. Molecular characterization was performed using Edman degradation, mass spectrometry and concanavalin A staining. Sera from patients allergic to chenopod pollen, as well as polyclonal and monoclonal antibodies raised against Ole e 1, were used in immunoblotting, ELISA and inhibition assays for immunological characterization of rChe a 1. The allergen was purified to homogeneity with a final yield of 15 mg/l of cell culture and showed a glycosylated character. N-terminal amino acid sequence of rChe a 1 and molecular mass were according to those of the protein isolated from chenopod pollen. The recombinant allergen maintained the IgG and IgE epitopes of the natural allergen deduced from the immunological assays. Structural and in vitro immunological properties of rChe a 1 produced in P. pastoris were equivalent to those of the natural form of the allergen and, thus, it could be used in testing patients allergic to chenopods. 2004 S. Karger AG, Basel.

  19. Overexpression, purification, crystallization and preliminary X-ray analysis of CheY4 from Vibrio cholerae O395

    International Nuclear Information System (INIS)

    Biswas, Maitree; Khamrui, Susmita; Sen, Udayaditya; Dasgupta, Jhimli

    2011-01-01

    The chemotaxis response regulator CheY4 from V. cholerae has been cloned, overexpressed, purified and crystallized in monoclinic and hexagonal space groups; the crystals diffracted to 1.67 and 1.9 Å resolution, respectively. Chemotaxis and motility greatly influence the infectivity of Vibrio cholerae, although the role of chemotaxis genes in V. cholerae pathogenesis is poorly understood. In contrast to the single copy of CheY found in Escherichia coli and Salmonella typhimurium, four CheYs (CheY1–CheY4) are present in V. cholerae. While insertional disruption of the cheY4 gene results in decreased motility, insertional duplication of this gene increases motility and causes enhanced expression of the two major virulence genes. Additionally, cheY3/cheY4 influences the activation of the transcription factor NF-κB, which triggers the generation of acute inflammatory responses. V. cholerae CheY4 was cloned, overexpressed and purified by Ni–NTA affinity chromatography followed by gel filtration. Crystals of CheY4 grown in space group C2 diffracted to 1.67 Å resolution, with unit-cell parameters a = 94.4, b = 31.9, c = 32.6 Å, β = 96.5°, whereas crystals grown in space group P3 2 21 diffracted to 1.9 Å resolution, with unit-cell parameters a = b = 56.104, c = 72.283 Å, γ = 120°

  20. CHE COSA RESTA DI CHERUBINI OGGI? DUE CASI DI STUDIO

    Directory of Open Access Journals (Sweden)

    Emanuele Miola

    2016-09-01

    Full Text Available A partire dagli anni Duemila, il fenomeno delle cosiddette risorgenze dialettali si è manifestato, nel panorama linguistico italiano, anche attraverso l’emergenza dei dialetti negli ambiti propri della Comunicazione Mediata dal Computer e, specialmente, sui siti internet creati ‘dal basso’, come l’enciclopedia libera e multilingue online Wikipedia. In questo articolo, si esaminerà il lascito di Cherubini e del suo Vocabolario milanese-italiano sull’edizione regionale lombarda della Wikipedia: gli articoli di quest’ultima saranno passati in rassegna, sia dal punto di vista ortografico, comparando le scelte del lessicografo milanese con quelle più in voga online, sia dal punto di vista morfo-sintattico, discutendo in questo secondo caso la presenza e la produttività di alcuni verbi sintagmatici. What remains of Cherubini today? Two case studies Since the beginning of the twenty-first century, the phenomenon of dialect resurgence has manifested in Italy through the emergence of dialects in Computer Mediated Communication, especially, on bottom-up created Web sites, like the free, multilingual, online encyclopedia Wikipedia. In this article, we will examine the legacy of Cherubini and his Milanese-Italian dictionary on the regional Lombard version of Wikipedia. We will review the articles both in terms of spelling, comparing the choices of Milanese lexicographer with those most utilized currently online, and from a morpho-syntactic point of view, discussing the presence and the productivity of some phrasal verbs.

  1. Nascita e destino della soggettività. Dai ruoli professionali ai processi di cura, attraverso una lettura di "Quel che resta del giorno" di Kazuo Ishiguro

    Directory of Open Access Journals (Sweden)

    Gabriele Profita

    2017-07-01

    Full Text Available Questa riflessione affronta un tema assai rilevante per le professioni di cura, con uno sguardo particolare alla psicoterapia. Per chiarire il ruolo della soggettività e della nascita e maturazione di un ruolo professionale riporterò un’analisi di un testo letterario attraverso il quale sarà più agevole scoprire come si forma l’identità di un ruolo professionale e come si avvia alla sua maturazione e alla sua codificazione. In particolare quali sono i rischi legati ad una sua rigida codificazione rivolta alla sua normatività tecnica? Mi propongo di tracciare un confronto con alcune forme di costruzione della soggettività che nel corso dei secoli hanno fondato il modello dell’uomo occidentale nelle sue articolazioni professionali.

  2. The Azospirillum brasilense Che1 chemotaxis pathway controls swimming velocity, which affects transient cell-to-cell clumping.

    Science.gov (United States)

    Bible, Amber; Russell, Matthew H; Alexandre, Gladys

    2012-07-01

    The Che1 chemotaxis-like pathway of Azospirillum brasilense contributes to chemotaxis and aerotaxis, and it has also been found to contribute to regulating changes in cell surface adhesive properties that affect the propensity of cells to clump and to flocculate. The exact contribution of Che1 to the control of chemotaxis and flocculation in A. brasilense remains poorly understood. Here, we show that Che1 affects reversible cell-to-cell clumping, a cellular behavior in which motile cells transiently interact by adhering to one another at their nonflagellated poles before swimming apart. Clumping precedes and is required for flocculation, and both processes appear to be independently regulated. The phenotypes of a ΔaerC receptor mutant and of mutant strains lacking cheA1, cheY1, cheB1, or cheR1 (alone or in combination) or with che1 deleted show that Che1 directly mediates changes in the flagellar swimming velocity and that this behavior directly modulates the transient nature of clumping. Our results also suggest that an additional receptor(s) and signaling pathway(s) are implicated in mediating other Che1-independent changes in clumping identified in the present study. Transient clumping precedes the transition to stable clump formation, which involves the production of specific extracellular polysaccharides (EPS); however, production of these clumping-specific EPS is not directly controlled by Che1 activity. Che1-dependent clumping may antagonize motility and prevent chemotaxis, thereby maintaining cells in a metabolically favorable niche.

  3. A CheR/CheB fusion protein is involved in cyst cell development and chemotaxis in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Wu, Lixian; Cui, Yanhua; Hong, Yuanyuan; Chen, Sanfeng

    2011-12-20

    We here report the sequence and functional analysis of cstB of Azospirillum brasilense Sp7. The predicted cstB contains C-terminal two PAS domains and N-terminal part which has similarity with CheB-CheR fusion protein. cstB mutants had reduced swarming ability compared to that of A. brasilense wild-type strain, implying that cstB was involved in chemotaxis in A. brasilense. A microscopic analysis revealed that cstB mutants developed mature cyst cells more quickly than wild type, indicating that cstB is involved in cyst formation. cstB mutants were affected in colony morphology and the production of exopolysaccharides (EPS) which are essential for A. brasilense cells to differentiate into cyst-like forms. These observations suggested that cstB was a multi-effector involved in cyst development and chemotaxis in A. brasilense. Copyright © 2010 Elsevier GmbH. All rights reserved.

  4. Il lungo freddo storia di Bruno Pontecorvo, lo scienziato che scelse l'URSS

    CERN Document Server

    Mafai, Miriam

    2012-01-01

    Nelle parole della grande giornalista recentemente scomparsa, la documentata narrazione della storia di Bruno Pontecorvo, fisico nucleare di fama mondiale che, nel pieno della Guerra fredda, scelse di abbandonare l'Occidente e di lavorare e vivere nell'Unione Sovietica. Grazie alla capacità della Mafai nel ricostruire gli eventi cruciali della vita di Pontecorvo in un nuovo quadro rivelatore, "Il lungo freddo" non offre solo un'inedita prospettiva sulla drammatica corsa alla bomba atomica - dalle decisive scoperte del Progetto Manhattan alla tragica esplosione di Hiroshima, dalla prima atomica sovietica alla bomba all'idrogeno - ma rappresenta soprattutto la memoria collettiva di una generazione che ha posto la politica al centro delle proprie scelte di vita. E svela i drammi umani di un conflitto che per più di quarant'anni ha diviso il mondo.

  5. The new Meyrin crèche takes its first steps

    CERN Multimedia

    2008-01-01

    The new Meyrin crèche was inaugurated on 10 October and already caters for 16 children of CERN personnel. Copyright: Laurent Barlier. Copyright: Robert Tillmann. At the end of August, the new Meyrin crèche in Champs-Fréchets, the Espace de Vie Enfantine (EVE), welcomed its first intake of infants. They included 16 children of members of the CERN personnel who are benefiting from the agreement signed in 2007 with the commune of Meyrin (see Bulletin n°43&44/2007). The crèche was officially inaugurated on 10 October with several CERN representatives in attendance, including HR Department Head, Enrico Chiaveri, and Head of the Relations with the Host States Service, Friedmann Eder. The following day, EVE held an open day for the inhabitants of Meyrin and interested members of the CERN personnel. The new 1516 m2 building ‘s spaces have very clean and ...

  6. Storie ‘vere’ ed eroine dei romanzi. Rappresentare la Somalia in 'Ilaria Alpi. La ragazza che voleva raccontare l’inferno' e 'Non dirmi che hai paura'

    Directory of Open Access Journals (Sweden)

    Simone Brioni

    2016-09-01

    Full Text Available ‘True’ Stories and Heroines in Novels: The Representation of Somalia in Ilaria Alpi: The Young Woman Who Wanted to Narrate Hell and Don’t Tell Me You Are AfraidThis article analyses Gigliola Alvisi’s Ilaria Alpi: La ragazza che voleva raccontare l’inferno [Ilaria Alpi: The Young Woman Who Wanted to Narrate the Hell] (2014 and Giuseppe Catozzella’s Non dirmi che hai paura [Don’t Tell Me You Are Afraid] (2014, two novels that deal with two recent events in Somali and Italian history, the killing of the journalist Ilaria Alpi in Mogadishu in 1994 and the death of Samia Yosuf Omar while she was trying to reach the Italian shores from Libya by boat. Alvisi’s text is analysed in comparison with other fictional and journalistic representations of Ilaria Alpi, while Non dirmi che hai paura is examined through what Catozzella considers the two constitutive dimensions of the novel: documentation and identification. Drawing on Stefano Jossa’s reflections on the construction of literary heroes, the article challenges Alvisi’s and Catozzella’s claims that they represent ‘true stories’. The article also argues that the main characters of these literary works are portrayed as heroines and role models for the emancipation of Muslim women.

  7. Crèche and School: Open Day on Saturday, 3 March

    CERN Multimedia

    EVE et École

    2018-01-01

    Open Day at Crèche and School of the CERN Staff Association Are you considering enrolling your child to the Crèche and School of the CERN Staff Association? If you work at CERN, then this event is for you: come visit the school and meet the Management on Saturday 3 March 2018 from 10 to 12 am It will be our pleasure to present to you our structure, its projects and premises, and answer any questions you may have. Please sign up for one of the two sessions via Doodle before Wednesday 28 February 2018: https://doodle.com/poll/3qvrb6m73pktqbft

  8. A crèche for CERN staff The Staff Association project

    CERN Multimedia

    Association du personnel

    2006-01-01

    For many years, the Staff Association has supported the demand for the creation of a crèche for the children of CERN staff. Several studies have been carried out without leading to a concrete plan. The fact that the CERN population is getting younger and the shortage of local facilities have led to a more urgent demand for this type of social service over the past few years. Furthermore, the Equal Opportunities Panel had already recommended that crèche places be made available.

  9. Demonstrating the Open Data Repository's Data Publisher: The CheMin Database

    Science.gov (United States)

    Stone, N.; Lafuente, B.; Bristow, T.; Pires, A.; Keller, R. M.; Downs, R. T.; Blake, D.; Dateo, C. E.; Fonda, M.

    2018-04-01

    The Open Data Repository's Data Publisher aims to provide an easy-to-use software tool that will allow researchers to create and publish database templates and related data. The CheMin Database developed using this framework is shown as an example.

  10. Trent'anni che sconvolsero la fisica la storia della teoria dei quanti

    CERN Document Server

    Gamow, George

    1993-01-01

    Gli anni dal 1900 al 1930 hanno portato un profondo mutamento nella visione che l'uomo aveva dell'universo: tra la prima idea di Max Planck dei quanti di luce nel 1900, e la previsione dell'esistenza delle antiparticelle formulata da P. A. M. Dirac nel 1929, corre un periodo di emozionanti progressi nel campo della fisica teorica.

  11. Reading Strategies: Issues in the Computerization of Machiavelli's "Il demonio che prese moglie".

    Science.gov (United States)

    Morgan, Leslie Zarker

    1994-01-01

    The ideal computer-based foreign language reading program must include cognitive background, a learning taxonomy, sound computer design, and knowledge of what is needed for the specific language. Machiavelli's "Il demonia che prese moglie" is chosen for study due to its historical interest. (63 references) (CK)

  12. The Emotional Communication in Hearing Questionnaire (EMO-CHeQ): Development and Evaluation.

    Science.gov (United States)

    Singh, Gurjit; Liskovoi, Lisa; Launer, Stefan; Russo, Frank

    2018-06-11

    The objectives of this research were to develop and evaluate a self-report questionnaire (the Emotional Communication in Hearing Questionnaire or EMO-CHeQ) designed to assess experiences of hearing and handicap when listening to signals that contain vocal emotion information. Study 1 involved internet-based administration of a 42-item version of the EMO-CHeQ to 586 adult participants (243 with self-reported normal hearing [NH], 193 with self-reported hearing impairment but no reported use of hearing aids [HI], and 150 with self-reported hearing impairment and use of hearing aids [HA]). To better understand the factor structure of the EMO-CHeQ and eliminate redundant items, an exploratory factor analysis was conducted. Study 2 involved laboratory-based administration of a 16-item version of the EMO-CHeQ to 32 adult participants (12 normal hearing/near normal hearing (NH/nNH), 10 HI, and 10 HA). In addition, participants completed an emotion-identification task under audio and audiovisual conditions. In study 1, the exploratory factor analysis yielded an interpretable solution with four factors emerging that explained a total of 66.3% of the variance in performance the EMO-CHeQ. Item deletion resulted in construction of the 16-item EMO-CHeQ. In study 1, both the HI and HA group reported greater vocal emotion communication handicap on the EMO-CHeQ than on the NH group, but differences in handicap were not observed between the HI and HA group. In study 2, the same pattern of reported handicap was observed in individuals with audiometrically verified hearing as was found in study 1. On the emotion-identification task, no group differences in performance were observed in the audiovisual condition, but group differences were observed in the audio alone condition. Although the HI and HA group exhibited similar emotion-identification performance, both groups performed worse than the NH/nNH group, thus suggesting the presence of behavioral deficits that parallel self

  13. A cheZ-Like Gene in Azorhizobium caulinodans Is a Key Gene in the Control of Chemotaxis and Colonization of the Host Plant.

    Science.gov (United States)

    Liu, Xiaolin; Liu, Wei; Sun, Yu; Xia, Chunlei; Elmerich, Claudine; Xie, Zhihong

    2018-02-01

    Chemotaxis can provide bacteria with competitive advantages for survival in complex environments. The CheZ chemotaxis protein is a phosphatase, affecting the flagellar motor in Escherichia coli by dephosphorylating the response regulator phosphorylated CheY protein (CheY∼P) responsible for clockwise rotation. A cheZ gene has been found in Azorhizobium caulinodans ORS571, in contrast to other rhizobial species studied so far. The CheZ protein in strain ORS571 has a conserved motif similar to that corresponding to the phosphatase active site in E. coli The construction of a cheZ deletion mutant strain and of cheZ mutant strains carrying a mutation in residues of the putative phosphatase active site showed that strain ORS571 participates in chemotaxis and motility, causing a hyperreversal behavior. In addition, the properties of the cheZ deletion mutant revealed that ORS571 CheZ is involved in other physiological processes, since it displayed increased flocculation, biofilm formation, exopolysaccharide (EPS) production, and host root colonization. In particular, it was observed that the expression of several exp genes, involved in EPS synthesis, was upregulated in the cheZ mutant compared to that in the wild type, suggesting that CheZ negatively controls exp gene expression through an unknown mechanism. It is proposed that CheZ influences the Azorhizobium -plant association by negatively regulating early colonization via the regulation of EPS production. This report established that CheZ in A. caulinodans plays roles in chemotaxis and the symbiotic association with the host plant. IMPORTANCE Chemotaxis allows bacteria to swim toward plant roots and is beneficial to the establishment of various plant-microbe associations. The level of CheY phosphorylation (CheY∼P) is central to the chemotaxis signal transduction. The mechanism of the signal termination of CheY∼P remains poorly characterized among Alphaproteobacteria , except for Sinorhizobium meliloti , which

  14. Noi siamo quello che ricordiamo - Le frazze di Crucoli: il teatro, il rito, il riscatto sociale

    Directory of Open Access Journals (Sweden)

    Tonia Mingrone

    2012-01-01

    Full Text Available Abstract - IT Questo lavoro nasce da una ricerca di campo sulle frazze, termine dialettale che indica le farse di Carnevale che si rappresentavano fino a cinquant’anni fa in molti paesi calabresi, tra cui il mio, Crucoli, in provincia di Crotone. Lo scopo di questo lavoro non è fare un resoconto esaustivo di tutto ciò che accadeva a Crucoli durante la celebrazione del Carnevale, impresa assai difficile dal momento che non ci sono documenti scritti e quindi bisogna affidarsi ai racconti orali delle persone intervistate, spesso non fedeli alla realtà, perché modificati dal tempo e dalla memoria. L’approccio con cui ho intrapreso questa ricerca è sicuramente legato all’aspetto teatrale e performativo dell’evento, senza trascurarne la rilevanza antropologica. Il materiale raccolto è frutto di interviste e colloqui con la gente del posto unito ad un grande lavoro di ricerca bibliografica di autori che avevano trattato di questo argomento in relazione ai loro paesi di origine.Lo scopo è quello di delineare l’organizzazione e lo svolgimento delle frazze, cercando di ricostruire la sua durata e le ripercussioni sulla comunità, nonché dimostrare ancora una volta come il teatro, messo a disposizione di alcuni eventi, diventi un mezzo forte di liberazione e di contestazione. Abstract - FR Cet article prend sa naissance par une recherche sur champ concernant les frazze, terme dialectal qui dénote les farces du Carnaval mises en scène jusqu'à il y a cinquante ans dans plusieurs villages en Calabria, entre eux le mien, Crucoli, dans la province de Crotone. La raison de ce travail n'est pas d'accomplir un compte rendu exhaustif de tout ce qui avait lieu à Crucoli pendant la célébration du Carnaval, l'exploit étant très difficile, du moment qu'aucun document écrit a été parvenu et par conséquence il est nécessaire de se remettre aux contes des témoins interviewés, souvent pas fidèles au réel, parce-que détournés par les

  15. Open Day at Crèche and School of the CERN Staff Association

    CERN Multimedia

    Staff Association

    2018-01-01

    In the morning of Saturday, 3 March 2018, the Crèche and School of the CERN Staff Association opened its doors for parents who wished to visit the establishment. Once again, the Open Day was a great success and brought together more than 50 families for two information sessions, which included: a general presentation of the establishment by the Headmistress, and a visit of the facilities led by the Headmistress and her deputy. At the end of the visit, parents were invited for a drink. This was an opportunity for both parents and professionals to have interesting discussions regarding the general conditions of the establishment and the pedagogical approach applied in the crèche and the school. The management team was delighted to offer the parents the opportunity to participate in this event, where everyone could express their views, ask questions and find answers in a friendly and relaxed atmosphere.

  16. Site-specific and synergistic stimulation of methylation on the bacterial chemotaxis receptor Tsr by serine and CheW

    Directory of Open Access Journals (Sweden)

    Weis Robert M

    2005-03-01

    Full Text Available Abstract Background Specific glutamates in the methyl-accepting chemotaxis proteins (MCPs of Escherichia coli are modified during sensory adaptation. Attractants that bind to MCPs are known to increase the rate of receptor modification, as with serine and the serine receptor (Tsr, which contributes to an increase in the steady-state (adapted methylation level. However, MCPs form ternary complexes with two cytoplasmic signaling proteins, the kinase (CheA and an adaptor protein (CheW, but their influences on receptor methylation are unknown. Here, the influence of CheW on the rate of Tsr methylation has been studied to identify contributions to the process of adaptation. Results Methyl group incorporation was measured in a series of membrane samples in which the Tsr molecules were engineered to have one available methyl-accepting glutamate residue (297, 304, 311 or 493. The relative rates at these sites (0.14, 0.05, 0.05 and 1, respectively differed from those found previously for the aspartate receptor (Tar, which was in part due to sequence differences between Tar and Tsr near site four. The addition of CheW generated unexpectedly large and site-specific rate increases, equal to or larger than the increases produced by serine. The increases produced by serine and CheW (added separately were the largest at site one, ~3 and 6-fold, respectively, and the least at site four, no change and ~2-fold, respectively. The rate increases were even larger when serine and CheW were added together, larger than the sums of the increases produced by serine and CheW added separately (except site four. This resulted in substantially larger serine-stimulated increases when CheW was present. Also, CheW enhanced methylation rates when either two or all four sites were available. Conclusion The increase in the rate of receptor methylation upon CheW binding contributes significantly to the ligand specificity and kinetics of sensory adaptation. The synergistic effect of

  17. CheShift-2 resolves a local inconsistency between two X-ray crystal structures

    International Nuclear Information System (INIS)

    Vila, Jorge A.; Sue, Shih-Che; Fraser, James S.; Scheraga, Harold A.; Dyson, H. Jane

    2012-01-01

    Since chemical shifts provide important and relatively accessible information about protein structure in solution, a Web server, CheShift-2, was developed for structure interrogation, based on a quantum mechanics database of 13 C α chemical shifts. We report the application of CheShift-2 to a local inconsistency between two X-ray crystal structures (PDB IDs 1IKN and 1NFI) of the complex between the p65/p50 heterodimer of NFκB and its inhibitor IκBα. The availability of NMR resonance assignments that included the region of the inconsistency provided an opportunity for independent validation of the CheShift-2 server. Application of the server showed that the 13 C α chemical shifts measured for the Gly270-Pro281 sequence close to the C-terminus of IκBα were unequivocally consistent with the backbone structure modeled in the 1IKN structure, and were inconsistent with the 1NFI structure. Previous NOE measurements had demonstrated that the position of a tryptophan ring in the region immediately N-terminal in this region was not consistent with either structure. Subsequent recalculation of the local structure in this region, based on the electron density of the deposited structure factors for 1IKN, confirmed that the local backbone structure was best modeled by 1IKN, but that the rotamer of Trp258 is consistent with the 1NFI structure, including the presence of a hydrogen bond between the ring NεH of Trp258 and the backbone carbonyl group of Gln278. The consensus between all of these measures suggests that the CheShift-2 server operates well under circumstances in which backbone chemical shifts are available but where local plasticity may render X-ray structural data ambiguous.

  18. Report to EuCheMS Division of Analytical Chemistry on CITAC Activity

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Wegsheider, Wolfhard

    Although the CITAC organisation [1] was founded on traceability, it embraces a variety of concepts allocated specifically to quality assurance. Collaboration with other organisations that promote practices and procedures of quality assurance is essential, and appointed liaison persons...... are encouraged to support this effort. In continuation of this aim a close contact to EuCheMS is desired together with contacts to IUPAC, ISO/REMCO, BIPM/CCQM, ILAC, EA, APLAC, EUROMET, SIM, APMP, AOACI, IAEA, IFCC and SADCMET....

  19. Il rischio tecnologico vantaggi e svantaggi del progresso scientifico

    CERN Document Server

    Lewis, H W

    1995-01-01

    I rischi della vita ; misurare il rischio ; la percezione del rischio ; la politica del rischio ; la valutazione del rischio ; la gestione del rischio ; il valore della vita ; qual è il livello "sufficiente" di sicurezza? ; incertezza, causalità, rilevabilità ; le delusioni della cautela ; sostanze chimiche tossiche ; sostanze chimiche cancerogene ; sicurezza sulle autostrade ; trasporto aereo ; radiazioni ionizzanti ; conbustibili fossili ; l'inverno nucleare ; radiazioni non ionizzanti ; quanto basta di statistica e di teoria delle probabilità ; epilogo : cosa significa tutto questo?.

  20. The Pseudomonas aeruginosa chemotaxis methyltransferase CheR1 impacts on bacterial surface sampling.

    Directory of Open Access Journals (Sweden)

    Juliane Schmidt

    Full Text Available The characterization of factors contributing to the formation and development of surface-associated bacterial communities known as biofilms has become an area of intense interest since biofilms have a major impact on human health, the environment and industry. Various studies have demonstrated that motility, including swimming, swarming and twitching, seems to play an important role in the surface colonization and establishment of structured biofilms. Thereby, the impact of chemotaxis on biofilm formation has been less intensively studied. Pseudomonas aeruginosa has a very complex chemosensory system with two Che systems implicated in flagella-mediated motility. In this study, we demonstrate that the chemotaxis protein CheR1 is a methyltransferase that binds S-adenosylmethionine and transfers a methyl group from this methyl donor to the chemoreceptor PctA, an activity which can be stimulated by the attractant serine but not by glutamine. We furthermore demonstrate that CheR1 does not only play a role in flagella-mediated chemotaxis but that its activity is essential for the formation and maintenance of bacterial biofilm structures. We propose a model in which motility and chemotaxis impact on initial attachment processes, dispersion and reattachment and increase the efficiency and frequency of surface sampling in P. aeruginosa.

  1. X-Ray Diffraction on Mars: Scientific Discoveries Made by the CheMin Instrument

    Science.gov (United States)

    Rampe, E. B.; Blake, D. F.; Ming, D. W.; Bristow, T. F.

    2017-01-01

    The Mars Science Laboratory Curiosity landed in Gale crater in August 2012 with the goal to identify and characterize habitable environments on Mars. Curiosity has been studying a series of sedimentary rocks primarily deposited in fluviolacustrine environments approximately 3.5 Ga. Minerals in the rocks and soils on Mars can help place further constraints on these ancient aqueous environments, including pH, salinity, and relative duration of liquid water. The Chemistry and Mineralogy (CheMin) X-ray diffraction and X-ray fluorescence instrument on Curiosity uses a Co X-ray source and charge-coupled device detector in transmission geometry to collect 2D Debye-Scherrer ring patterns of the less than 150 micron size fraction of drilled rock powders or scooped sediments. With an angular range of approximately 2.52deg 20 and a 20 resolution of approximately 0.3deg, mineral abundances can be quantified with a detection limit of approximately 1-2 wt. %. CheMin has returned quantitative mineral abundances from 16 mudstone, sandstone, and aeolian sand samples so far. The mineralogy of these samples is incredibly diverse, suggesting a variety of depositional and diagenetic environments and different source regions for the sediments. Results from CheMin have been essential for reconstructing the geologic history of Gale crater and addressing the question of habitability on ancient Mars.

  2. Pretreatment with P-Nitrophenyl Phosphoramides: Spontaneous Reactivation of Blood ChE after Oral Administration to Guinea Pigs

    National Research Council Canada - National Science Library

    Polhuijs, M

    1997-01-01

    ... and of the reference compounds pyridostigmine and physostigmine has been studied in the guinea pig, as determined by measuring spontaneous reactivation of blood ChE inhibited by these pretreatment compounds...

  3. Distinct Domains of CheA Confer Unique Functions in Chemotaxis and Cell Length in Azospirillum brasilense Sp7.

    Science.gov (United States)

    Gullett, Jessica M; Bible, Amber; Alexandre, Gladys

    2017-07-01

    Chemotaxis is the movement of cells in response to gradients of diverse chemical cues. Motile bacteria utilize a conserved chemotaxis signal transduction system to bias their motility and navigate through a gradient. A central regulator of chemotaxis is the histidine kinase CheA. This cytoplasmic protein interacts with membrane-bound receptors, which assemble into large polar arrays, to propagate the signal. In the alphaproteobacterium Azospirillum brasilense , Che1 controls transient increases in swimming speed during chemotaxis, but it also biases the cell length at division. However, the exact underlying molecular mechanisms for Che1-dependent control of multiple cellular behaviors are not known. Here, we identify specific domains of the CheA1 histidine kinase implicated in modulating each of these functions. We show that CheA1 is produced in two isoforms: a membrane-anchored isoform produced as a fusion with a conserved seven-transmembrane domain of unknown function (TMX) at the N terminus and a soluble isoform similar to prototypical CheA. Site-directed and deletion mutagenesis combined with behavioral assays confirm the role of CheA1 in chemotaxis and implicate the TMX domain in mediating changes in cell length. Fluorescence microscopy further reveals that the membrane-anchored isoform is distributed around the cell surface while the soluble isoform localizes at the cell poles. Together, the data provide a mechanism for the role of Che1 in controlling multiple unrelated cellular behaviors via acquisition of a new domain in CheA1 and production of distinct functional isoforms. IMPORTANCE Chemotaxis provides a significant competitive advantage to bacteria in the environment, and this function has been transferred laterally multiple times, with evidence of functional divergence in different genomic contexts. The molecular principles that underlie functional diversification of chemotaxis in various genomic contexts are unknown. Here, we provide a molecular

  4. L’immaginazione al lavoro. Che cosa e come conosciamo dal romanzo

    Directory of Open Access Journals (Sweden)

    Gianluca Consoli

    2011-12-01

    Full Text Available L’articolo delinea i fondamenti di un’epistemologia del romanzo, rispondendo alle domande di base: che cosa e come possiamo conoscere attraverso il romanzo. A partire dalla definizione del romanzo come racconto di finzione, viene sviluppata  una posizione di cognitivismo radicale, per la quale il romanzo (a produce conoscenza modale; (b giustifica questa conoscenza in base al principio della verosimiglianza; (c favorisce l’apprendimento per esperienza in virtù dell’esemplificazione immaginativa. Le tesi proposte vengono corroborate in riferimento ai recenti dati sperimentali ottenuti dalle scienze cognitive, in particolare dalla psicologia cognitiva, sull’immaginazione, la finzione, la simulazione.

  5. Crew Health Care System (CHeCS) Design Research, Documentations, and Evaluations

    Science.gov (United States)

    CLement, Bethany M.

    2011-01-01

    The Crew Health Care System (CHeCS) is a group within the Space Life Science Directorate (SLSD) that focuses on the overall health of astronauts by reinforcing the three divisions - the Environmental Maintenance System (EMS), the Countermeasures System (CMS), and the Health Maintenance System (HMS). This internship provided opportunity to gain knowledge, experience, and skills in CHeCS engineering and operations tasks. Various and differing tasks allowed for occasions to work independently, network to get things done, and show leadership abilities. Specific exercises included reviewing hardware certification, operations, and documentation within the ongoing Med Kit Redesign (MKR) project, and learning, writing, and working various common pieces of paperwork used in the engineering and design process. Another project focused on the distribution of various pieces of hardware to off-site research facilities with an interest in space flight health care. The main focus of this internship, though, was on a broad and encompassing understanding of the engineering process as time was spent looking at each individual step in a variety of settings and tasks.

  6. Finally a crèche at CERN, thanks to the Staff Association

    CERN Multimedia

    Staff Association

    2013-01-01

    Setting up at CERN a collective structure to mind children younger than two years, a so-called “crèche”, has been discussed at least since the early 1990s. Then, in February 2001, the Equal Opportunities Advisory Panel produced a memo to the Director of Administration in which it “invites the CERN Management to re-consider the possibility of creating a crèche at CERN”. As a result an ad hoc task force (“Bethléem”) was set up, which based its work on an informal questionnaire sent to CERN families with small children. Its study came up with some relevant parameters for “should CERN Management intend to undertake a minimal effort toward solving the crèche problem for its staff members”. Nothing was undertaken at that time. In the framework of the 2005 five yearly review “Working Group 6: Crèche” made another study of public and private  cr&a...

  7. Serum cholinesterase polymorphism (CHE1 and CHE2 loci) among several Indian groups from Amazon region of Brazil, and segregation of the C5 variant in families.

    Science.gov (United States)

    Guerreiro, J F; Santos, S E; Aguiar, G F

    1989-04-01

    Eight Indian tribes from the Amazon region of Brazil (Araweté, Arara, Yamamadi, Kararaô, Karitiana, Waiampi, Surui and Cinta Larga) were studied for the distribution of the atypical and C5 variants of serum cholinesterase. None of them presented the CHE1*A allele, but the C5 variant was found in the Araweté (20.4%), Kararaô (15.6%), Karitiana (50.5%), Surui (12.3%) and Cinta Larga (19.6%) tribes. The frequency of the C5+ phenotype in the Karitiana is the highest reported thus far in human populations. Segregation studies considering the C5 variant were made among the Karitiana, and also among the Urubu-Kaapor and Munduruku tribes previously studied by Guerreiro et al [1987a, 1987b]. Most of the data were in agreement with the genetic hypothesis, but they also revealed a significant lack of the C5+ phenotype in offspring from C5+ X C5+ matings, as well as the occurrence of two C5+ children from C5- X C5- unions, in the Urubu-Kaapor tribe.

  8. The new "Jardin de Capucine" crèche brings a breath of fresh air for young CERN parents

    CERN Multimedia

    HR Department

    2011-01-01

    On 19 January 2011, CERN's Director-General, Rolf Heuer, signed an agreement with the company "Le Jardin de Zébulon" for the provision of 40 places at the "Jardin de Capucine", a new private crèche due to open this autumn.   In 2008, the "Jardin de Zébulon", a private bilingual crèche for children aged 1 to 4, was opened by Ariane Boucheron at the Technoparc industrial estate in Saint-Genis Pouilly (France). The following year, the number of places was increased from 20 to 37 to meet demand. The "Jardin de Zébulon" has taken in a number of children of CERN personnel ever since it was created. With no let-up in the demand for new crèche places, Ariane Boucher is currently engaged in the construction of a new centre, the "Jardin de Capucine", next-door to the existing crèche. Forty places at the new crèche will...

  9. Astrobiological Significance of Definitive Mineralogical Analysis of Martian Surface Samples Using the CheMin XRD/XRF Instrument

    Science.gov (United States)

    Feldman, S. M.; Blake, D. F.; Sarrazin, P.; Bish, D. L.; Chipera, S. J.; Vaniman, D. T.; Collins, S.

    2004-01-01

    The search for evidence of habitability, or of extant or extinct life on Mars, will initially be a search for evidence of past or present conditions supportive of life. The three key requirements for the emergence of life are thought to be liquid water; a suitable energy source; and chemical building blocks. CheMin is a miniaturized XRD/XRF (X-Ray diffraction / X-ray fluorescence) instrument which has been developed for definitive mineralogic analysis of soils and rocks on the Martian surface. The CheMin instrument can provide information that is highly relevant to each of these habitability requirements as summarized below.

  10. CheD: chemical database compilation tool, Internet server, and client for SQL servers.

    Science.gov (United States)

    Trepalin, S V; Yarkov, A V

    2001-01-01

    An efficient program, which runs on a personal computer, for the storage, retrieval, and processing of chemical information, is presented, The program can work both as a stand-alone application or in conjunction with a specifically written Web server application or with some standard SQL servers, e.g., Oracle, Interbase, and MS SQL. New types of data fields are introduced, e.g., arrays for spectral information storage, HTML and database links, and user-defined functions. CheD has an open architecture; thus, custom data types, controls, and services may be added. A WWW server application for chemical data retrieval features an easy and user-friendly installation on Windows NT or 95 platforms.

  11. Lessons Learned from the Crew Health Care System (CHeCS) Rack 1 Environmental Control and Life Support (ECLS) Design

    Science.gov (United States)

    Williams, David E.

    2006-01-01

    This paper will provide an overview of the International Space Station (ISS) Environmental Control and Life Support (ECLS) design of the Crew Health Care System (CHeCS) Rack 1 and it will document some of the lessons that have been learned to date for the ECLS equipment in this rack.

  12. Efficient Computation of Sparse Matrix Functions for Large-Scale Electronic Structure Calculations: The CheSS Library.

    Science.gov (United States)

    Mohr, Stephan; Dawson, William; Wagner, Michael; Caliste, Damien; Nakajima, Takahito; Genovese, Luigi

    2017-10-10

    We present CheSS, the "Chebyshev Sparse Solvers" library, which has been designed to solve typical problems arising in large-scale electronic structure calculations using localized basis sets. The library is based on a flexible and efficient expansion in terms of Chebyshev polynomials and presently features the calculation of the density matrix, the calculation of matrix powers for arbitrary powers, and the extraction of eigenvalues in a selected interval. CheSS is able to exploit the sparsity of the matrices and scales linearly with respect to the number of nonzero entries, making it well-suited for large-scale calculations. The approach is particularly adapted for setups leading to small spectral widths of the involved matrices and outperforms alternative methods in this regime. By coupling CheSS to the DFT code BigDFT, we show that such a favorable setup is indeed possible in practice. In addition, the approach based on Chebyshev polynomials can be massively parallelized, and CheSS exhibits excellent scaling up to thousands of cores even for relatively small matrix sizes.

  13. Molecular Interaction and Cellular Location of RecA and CheW Proteins in Salmonella enterica during SOS Response and Their Implication in Swarming.

    Science.gov (United States)

    Irazoki, Oihane; Aranda, Jesús; Zimmermann, Timo; Campoy, Susana; Barbé, Jordi

    2016-01-01

    In addition to its role in DNA damage repair and recombination, the RecA protein, through its interaction with CheW, is involved in swarming motility, a form of flagella-dependent movement across surfaces. In order to better understand how SOS response modulates swarming, in this work the location of RecA and CheW proteins within the swarming cells has been studied by using super-resolution microscopy. Further, and after in silico docking studies, the specific RecA and CheW regions associated with the RecA-CheW interaction have also been confirmed by site-directed mutagenesis and immunoprecipitation techniques. Our results point out that the CheW distribution changes, from the cell poles to foci distributed in a helical pattern along the cell axis when SOS response is activated or RecA protein is overexpressed. In this situation, the CheW presents the same subcellular location as that of RecA, pointing out that the previously described RecA storage structures may be modulators of swarming motility. Data reported herein not only confirmed that the RecA-CheW pair is essential for swarming motility but it is directly involved in the CheW distribution change associated to SOS response activation. A model explaining not only the mechanism by which DNA damage modulates swarming but also how both the lack and the excess of RecA protein impair this motility is proposed.

  14. Molecular interaction and cellular location of RecA and CheW proteins in Salmonella enterica during SOS response and their implication in swarming

    Directory of Open Access Journals (Sweden)

    Oihane Irazoki

    2016-10-01

    Full Text Available In addition to its role in DNA damage repair and recombination, the RecA protein, through its interaction with CheW, is involved in swarming motility, a form of flagella-dependent movement across surfaces. In order to better understand how SOS response modulates swarming, in this work the location of RecA and CheW proteins within the swarming cells has been studied by using super-resolution microscopy. Further, and after in silico docking studies, the specific RecA and CheW regions associated with the RecA-CheW interaction have also been confirmed by site-directed mutagenesis and immunoprecipitation techniques. Our results point out that the CheW distribution changes, from the cell poles to foci distributed in a helical pattern along the cell axis when SOS response is activated or RecA protein is overexpressed. In this situation, the CheW presents the same subcellular location as that of RecA, pointing out that the previously described RecA storage structures may be modulators of swarming motility. Data reported herein not only confirmed that the RecA-CheW pair is essential for swarming motility but it is directly involved in the CheW distribution change associated to SOS response activation. A model explaining not only the mechanism by which DNA damage modulates swarming but also how both the lack and the excess of RecA protein impair this motility is proposed.

  15. European analytical column No. 36 from the Division of Analytical Chemistry (DAC) of the European Association for Chemical and Molecular Sciences (EuCheMS)

    DEFF Research Database (Denmark)

    Karlberg, Bo; Emons, Hendrik; Andersen, Jens Enevold Thaulov

    2008-01-01

    European analytical column no. 36 from the division of analytical chemistry (DAC) of the European association for chemical and molecular sciences (EuCheMS)......European analytical column no. 36 from the division of analytical chemistry (DAC) of the European association for chemical and molecular sciences (EuCheMS)...

  16. Il Salento che abbiamo attraversato: Rina Durante e Bruno Brancher, il racconto di due vite diverse sulle strade di terra d'Otranto

    Directory of Open Access Journals (Sweden)

    Massimo Melillo

    2015-07-01

    Full Text Available Rina Durante ha rappresentato il meglio della cultura meridionale, ne ha raccolto l’eredità e ne è stata tra le interpreti più acute. Abbiamo avuto l’onore della sua amicizia fraterna e solidale, conosciuto l’azzardo e la radicalità delle sue scelte di vita, la sua dolce timidezza e l’ardita padronanza e consapevolezza del suo ruolo: anni di discussioni, di confronto, di legame cementato da infuocati innamoramenti intellettuali per uno scrittore, un poeta, un regista, di accese ironie sui nostri caratteri, di scontri politici e furibondi litigi finiti in un abbraccio. Anche per Bruno Brancher, milanese di tutti e di nessuno, il ricordo si fa memoria per le sue mille improvvise e imprevedibili incursioni in terra salentina. Non era un uomo facile, anche se aveva dalla sua parte il puntiglio dell’innocenza tipica del ladro gentiluomo. Portava leggero il fardello di due vite in una: la prima segnata da una marginalità, fattasi a volte precariamente lussuosa con i proventi di furti e disarmanti rapine; l’altra con la faccia del redento, che con la scoperta della scrittura diventa cosciente di sé.

  17. El Che - más que médico

    Directory of Open Access Journals (Sweden)

    Natalia I. Osorio Curbelo

    2015-12-01

    Full Text Available Revolucionario, dirigente político, comandante guerrillero, intelectual y médico.  Uno de los íconos del siglo XX.  Nació en Rosario, Argentina, el 14 de junio de 1928. En 1938, con apenas 10 años, el padre le enseñó a jugar Ajedrez en el transcurso del año, deporte que no dejaría de practicar nunca más y lo estudiaría por siempre. En 1939 supo de la existencia de Cuba, pues teniendo 11 años, cuando vivía en Alta Gracia, en Buenos Aires se desarrollaba la VII Olimpiada de Ajedrez y el más conocido de los ajedrecistas cubanos José Raúl Capablanca, obtuvo la medalla de Oro en el primer tablero, convirtiéndose en noticia mundial. La gran pasión por el juego ciencia  se puso de manifiesto durante toda su vida, jugó Ajedrez cuando estaba viajando en un avión, cuando  estuvo detenido en alguna estación policial o, simplemente, a las tres de la madrugada recibía una delegación mexicana para jugar una partida después de conversar sobre los temas generales comunes. Ernesto Guevara, eternamente Che, revolucionario integral y multifacético, sintió gran afición por los deportes y aunque por lo general se le cita como amante del ajedrez y el fútbol, también, desde niño, practicó con derroche de coraje y voluntad otros no tan divulgados. A sus prácticas deportivas también se entregó con la voluntad, coraje y pasión que lo caracterizaron a lo largo de su vida. Luego del triunfo de la Revolución cubana, en la que ganó  los grados de Comandante, hubo  un deporte priorizado  en la vida del Che: el Ajedrez.  Dos veces ganó en los campeonatos patrocinados por el Ministerio de Industria, que él presidía,  y participó, además, en los Torneos del INDER donde ascendió, por los resultados alcanzados, a la primera categoría. Se enfrentó en partidas simultáneas a varios de los mejores jugadores de esos días, entre ellos los grandes maestros soviéticos Victor Korchnoi y Mijail Tal y el argentino Miguel Najdorf, d

  18. RELÉ ELECTRÓNICO PARA LA DETECCIÓN DEL MOVIMIENTO EN LOS TANQUES DE SEDIMENTACIÓN DE LA EMPRESA COMANDANTE ¨ERNESTO CHE GUEVARA¨

    Directory of Open Access Journals (Sweden)

    Orlys Ernesto Torres Breffe

    2011-02-01

    Full Text Available En este trabajo se muestran los resultados del diseño de un dispositivo electrónico para detectar el movimiento del tanquede sedimentación de la planta de lixiviación de la Empresa Ernesto Che Guevara.Estos tanque actualmente se encuentran sin esta protección y su parada por avería solo es detectada de forma visual por eloperario o cuando la densidad de la pulpa aumente a valores tan altos que sea reflejado en el sistema de monitoreo instalado(EROS. La parada inadvertida de estos tanque casi siempre sucede por razones fácilmente corregibles, pero si no se detectaa tiempo la sedimentación del minerales es casi inevitable y las pérdidas de recursos y materiales son cuantiosas.La propuesta electrónica en sustitución a las desechas electromagnéticas, es muy barata y su reproducción es fácilmenterealizable en la propia empresa, dado que los elementos que se utiliza son clásicos, sin exigencias de fabricación, tolerancias,etc.  The main goal of this research paper is to show the electronic device design results while dealing with the location of thesedimentation tank on the leaching plant located on Ernesto Che Guevara factory.Nowadays there is no protection for this tank, thus, if it stops working it can only be noticed by the engine sunner on avisual way or when the extremely high figures of the pulp density are reflected on the available monitor system (EROS.The unnoticed misfunctioning of this device is caused mainly to easily solved reasons. Nevertheless, when not detected ontime, the mineral sedimentation is almost unavoidable which results on the losses of resources.The electronic proposal to substitute the electromagnetic scraps is very cheap and easily to reproduce on the factory itself forthe needed elements are classic with no resistance and manufacture demands.

  19. Cherenkov and scintillation light separation on the CheSS experiment

    Science.gov (United States)

    Caravaca, Javier; Land, Benjamin; Descamps, Freija; Orebi Gann, Gabriel D.

    2016-09-01

    Separation of the scintillation and Cherenkov light produced in liquid scintillators enables outstanding capabilities for future particle detectors, the most relevant being: particle directionality information in a low energy threshold detector and improved particle identification. The CheSS experiment uses an array of small, fast photomultipliers (PMTs) and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in liquid scintillator using two techniques: based on the photon density and using the photon hit time information. A charged particle ionizing a scintillation medium produces a prompt Cherenkov cone and late isotropic scintillation light, typically delayed by several ns. The fast response of our PMTs and DAQ provides a precision well below the ns level, making possible the time separation. Furthermore, the usage of the new developed water-based liquid scintillators (WbLS) enhances the separation since it allows tuning of the Cherenkov/Scintillation ratio. Latest results on the separation for pure liquid scintillators and WbLS will be presented.

  20. Start of enrolment for the Champs-Fréchets crèche (EVE)

    CERN Multimedia

    HR Department

    2008-01-01

    As announced in Bulletin 43/2007, CERN signed an agreement with the commune of Meyrin on 17 October 2007 under which 20 places will be reserved for the children of CERN personnel in the Champs-Fréchets day care centre (EVE), which will open on Monday, 25 August, and CERN will contribute to the funding. This agreement allows members of the CERN personnel (employees and associates) access to the crèche, for children aged between 4 months and 4 years, irrespective of where they are living. Applications for the school year starting autumn 2008 will be accepted from Monday 17 March until Monday 30 June 2008. Members of the personnel must complete the enrolment formalities with the Meyrin infant education service themselves: Mairie de Meyrin Service de la Petite Enfance 2 rue des Boudines Case postale 367 - 1217 Meyrin 1 - Tel. + 41 (0)22 782 21 21 mailto:meyrin@meyrin.ch http://www.meyrin.ch/petiteenfance Application forms (in PDF) can be downloaded from the website of the com...

  1. SI Notes.

    Science.gov (United States)

    Nelson, Robert A.

    1983-01-01

    Discusses legislation related to SI (International Systems of Units) in the United States. Indicates that although SI metric units have been officially recognized by law in the United States, U.S. Customary Units have never received a statutory basis. (JN)

  2. LE SOLUTRÉEN ANCIEN EN ARDÈCHE (FRANCE: UNE RÉVISION CRITIQUE DES INDUSTRIES LITHIQUES

    Directory of Open Access Journals (Sweden)

    Sophie Guegan

    2013-11-01

    Full Text Available S’inscrivant dans un travail de Doctorat sur les peuplements des deux rives de la vallée du Rhône au Maximum Glaciaire, cet article propose un état des connaissances sur la phase ancienne du Solutréen en Ardèche (rive droite du Rhône, donnant lieu à une révision critique des industries lithiques s’y rapportant. En effet, depuis les travaux de P.E.L. Smith et J. Combier, et plus récemment le travail d’A. Barbiero consacré aux pointes à face plance et pointes à cran d’une collection ancienne à la Baume d’Oullins (Gard-Ardèche, France, aucun réexamen global n’avait été entrepris. Trois gisements de référence pour cette phase ancienne, ont ainsi été sélectionnés: les grottes d’Oullins (Gard-Ardèche, France, de Chabot (Gard, France et de Granouly (Ardèche, France. Nous présentons ici les réslutats préliminaires à cette étude. En premier lieu, une approche typologique a été menée principalement autour de la pointe à face plane, objet emblématique de cette phase, permettant d’en préciser les principaux caractères. Dans un deuxième temps, une approche technologique a permis de confirmer l’homogénéité dans les choix techniques des Solutréens entre l’Ardèche et les régions du Sud-Ouest et du Bassin Parisien. Enfin, une étude des matières premières, a révélé pour l’heure des choix économiques étonnants pour le contexte paléo-climatique, avec des déplacements vers le nords et un franchissement du Rhône.In the frame of a doctoral dissertation on the Late Glacial Maximum occupations of both sides of the Rhône valley, this paper presents a state of the art and a critical reappraisal of the lithic assemblages from the early phases of the Solutrean in Ardeche (right bank of the Rhône river. Indeed, since the works of P.E.L. Smith and J. Combier, except the work of A. Barbiero, on the unifacial leaf-points and shouldered points from Baume d'Oullins, no complete study of these

  3. Méthodes de levée de dormance de la noix de cola fraîche ( Cola ...

    African Journals Online (AJOL)

    Cette étude avait pour objectif de proposer une méthode efficace de germination de la noix de cola fraîche, en vue d'une réduction significative du délai de germination à travers un test comparatif de traitement de la noix par blessure, humidification et chaleur. Méthodologie et résultats: L'étude a été mise en place selon un ...

  4. “Nell’occhio che riscopre la luce”: tempo, Storia e memoria nella poesia di Salvatore Quasimodo

    OpenAIRE

    Alessandro Martini

    2015-01-01

    La riflessione sul rapporto dell’uomo con il tempo e con la storia percorre senza soluzione di continuità l’opera poetica di Salvatore Quasimodo. Spesso a disagio in una dimensione temporale fissa e definita, schiacciato tra dolore dell’esilio, insensatezza della guerra e crisi del dopoguerra, il poeta interroga gli evi passati e le ere future in cerca di un’armonia che appare il più delle volte sfuggente.

  5. The chemotaxis-like Che1 pathway has an indirect role in adhesive cell properties of Azospirillum brasilense.

    Science.gov (United States)

    Siuti, Piro; Green, Calvin; Edwards, Amanda Nicole; Doktycz, Mitchel J; Alexandre, Gladys

    2011-10-01

    The Azospirillum brasilense chemotaxis-like Che1 signal transduction pathway was recently shown to modulate changes in adhesive cell surface properties that, in turn, affect cell-to-cell aggregation and flocculation behaviors rather than flagellar-mediated chemotaxis. Attachment to surfaces and root colonization may be functions related to flocculation. Here, the conditions under which A. brasilense wild-type Sp7 and che1 mutant strains attach to abiotic and biotic surfaces were examined using in vitro attachment and biofilm assays combined with atomic force microscopy and confocal microscopy. The nitrogen source available for growth is found to be a major modulator of surface attachment by A. brasilense and could be promoted in vitro by lectins, suggesting that it depends on interaction with surface-exposed residues within the extracellular matrix of cells. However, Che1-dependent signaling is shown to contribute indirectly to surface attachment, indicating that distinct mechanisms are likely underlying flocculation and attachment to surfaces in A. brasilense. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  6. Reconocimiento Mapu-Che de Chile: Tratado ante Constitución, Historia frente a Derecho

    Directory of Open Access Journals (Sweden)

    Bartolomé CLAVERO SALVADOR

    2011-04-01

    Full Text Available Desde el año 1991, el compromiso adquirido por los sucesivos gobiernos chilenos para reconocer a nivel constitucional la presencia indígena en el ordenamiento del Estado ha puesto de manifiesto el desconocimiento académico y jurídico mutuo por parte de Chile con respecto a las evidencias para una reposición de Mapu-Che. El presente trabajo hace un recorrido histórico y jurídico por las formas de relación entre el Estado chileno y el Estado Mapu, que hasta la conquista chilena de Mapu en la década de los ochenta del siglo XIX se manifestaron a través de Tratados y Parlamentos que implicaban un reconocimiento mutuo de ambas entidades en una esfera internacional. Las comisiones de estudios, informes oficiales e invocaciones de verdad para un nuevo trato, primero de las Naciones Unidas, y después de la República de Chile, han observado estas evidencias de la significación constitucional e internacional de los Tratados, pero Chile ha convertido su peculiar forma de reconocimiento constitucional de la presencia indígena en un alarde de unidad e indivisibilidad nacional. Este encubrimiento nace del deseo de mantener una Constitución exclusiva, al que se une la certeza de que otra forma de reconocimiento obligaría a un replanteamiento de las propias raíces de los fundamentos constitucionales de la República de Chile.

  7. SYM1, l’ortologo di lievito del gene umano MPV17, codifica per una proteina indotta da stress che modula lo stato bioenergetico e morfogenetico del mitocondrio

    OpenAIRE

    Dallabona, Cristina

    2010-01-01

    Mutazioni nel gene MPV17 causano l’insorgenza di una forma epatocerebrale della sindrome da deplezione del DNA mitocondriale. MPV17 codifica per una piccola proteina idrofobica localizzata nella membrana mitocondriale interna con funzione sconosciuta. Per cercare di chiarire le basi molecolari che causano la patologia, abbiamo utilizzato il lievito S. cerevisiae come organismo modello grazie alla presenza di un ortologo di MPV17: SYM1. Abbiamo dimostrato che la proteina Sym1 è essenziale per ...

  8. Quality of the Fosso della Casaccia: analysis of the macroinvertebrates colonizing artificial substrates; Stato di qualita` del fosso della Casaccia: analisi dei macroinvertebrati che colonizzano substrati artificiali

    Energy Technology Data Exchange (ETDEWEB)

    Prato, S.; Morgana, J.G.; Antonelli, D.; Folletto, A. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente

    1999-01-01

    Aim of this work is to analyse the environmental quality of a small stream, the Fosso della Casaccia, flowing near Research Centre of ENEA (Rome, Central Italy). The study was carried out comparing zoo benthic communities of two sampling sites, chosen upstream and downstream the sewage of the Research Centre. Macro invertebrates were sampled using artificial substrates and standard hand net. Taxa number and distribution along along the watercourse were compared. Moreover, biotic index values (I.B.E.=Indice Biotico Esteso) were calculated using data on macro invertebrates collected with both sampling methodologies. Artificial substrates were also useful in establishing colonization patterns at each sampling site, and bio masses of individuals belonging to different trophic groups. The results show the greater sampling effectiveness of artificial substrates, confirming their usefulness for establishing the environmental quality. [Italiano] Il presente lavoro prende in considerazione la qualita` ambientale del Fosso della Casaccia, un piccolo corso d`acqua che scorre in prossimita` del Centro di Ricerche ENEA Casaccia (Italia Centrale). Lo studio e` stato realizzato in base al confronto fra le comunita` zoobentoniche di due stazioni sperimentali situate a monte e a valle dello scarico di acque reflue del centro. Il campionamento dei macroinvertebrati e` stato effettuato utilizzando due diversi metodi di raccolta: i substrati artificiali e il retino immanicato standard. Gli organismi sono stati classificati in unita` sistematiche, e si e` analizzata la loro distribuzione lungo il corso d`acqua. Inoltre sono stati calcolati i valori degli indici biotici I.B.E. (Indice Biotico Esteso) utilizzando i dati ottenuti con le due metodologie di campionamento. L`uso di substrati artificiali in ogni stazione di campionamento e` stato utile anche per stabilire il tipo di colonizzazione, l`abbondanza e le biomasse degli individui appartenenti ai vari gruppi trofici. I nostri

  9. The structure and dynamic properties of the complete histidine phosphotransfer domain of the chemotaxis specific histidine autokinase CheA from Thermotoga maritima

    International Nuclear Information System (INIS)

    Vu, Anh; Hamel, Damon J.; Zhou Hongjun; Dahlquist, Frederick W.

    2011-01-01

    The bacterial histidine autokinase CheA contains a histidine phosphotransfer (Hpt) domain that accepts a phosphate from the catalytic domain and donates the phosphate to either target response regulator protein, CheY or CheB. The Hpt domain forms a helix-bundle structure with a conserved four-helix bundle motif and a variable fifth helix. Observation of two nearly equally populated conformations in the crystal structure of a Hpt domain fragment of CheA from Thermotoga maritima containing only the first four helices suggests more mobility in a tightly packed helix bundle structure than previously thought. In order to examine how the structures of Hpt domain homologs may differ from each other particularly in the conformation of the last helix, and whether an alternative conformation exists in the intact Hpt domain in solution, we have solved a high-resolution, solution structure of the CheA Hpt from T. maritima and characterized the backbone dynamics of this protein. The structure contains a four-helix bundle characteristic of histidine phosphotransfer domains. The position and orientation of the fifth helix resembles those in known Hpt domain crystal and solution structures in other histidine kinases. The alternative conformation that was reported in the crystal structure of the CheA Hpt from T. maritima missing the fifth helix is not detected in the solution structure, suggesting a role for the fifth helix in providing stabilizing forces to the overall structure.

  10. The Crèche and School structure of the CERN Staff Association is looking for a new name

    CERN Multimedia

    Staff Association

    2018-01-01

    The CERN Staff Association is launching a competition to find a new name to replace the current acronym EVEE (Espace de Vie Enfantine et École). The competition is open to everyone from Thursday, 1 February 2018 to Thursday, 15 March. All participants can send their name suggestions via the form available on the websites of the Staff Association and the Crèche and School. Good luck to all – may the best one win! P.S. The Rules of the Competition are available on both websites

  11. Determination of the Index of Consumption of Petroleum of the Calcining Kiln of the Ernesto Che Guevara Commander Undertaking

    Directory of Open Access Journals (Sweden)

    Yarilys Gaínza-Delgado

    2016-07-01

    Full Text Available This work presents the results obtained in carrying out the mass and energy balances in the calcining kiln of the company commander Ernesto Che Guevara, for determining the consumption index of petroleum used for obtaining nickel oxide through thermal decomposition of the basic nickel carbonate. It was shown that for a production of basic nickel carbonate of              12 t / h with 69% moisture, it is necessary to feed about 1100 kg / h of fuel, for an consumption index of 91.67 kg of fuel per ton of load.

  12. Crèche and School of the Staff Association: a programme for children from 2 to 4 year old

    CERN Multimedia

    Staff Association

    2018-01-01

    Find out how children between the ages of two to four and their families can benefit from the Staff Association Crèche and School programme. Classes for children aged between two and four years have been set-up to ensure the initial transition from home to school is as smooth as possible. Children attend mornings only and are welcomed by the same group of teaching staff throughout the week, allowing the children to establish a link between their home life and the crèche/school. The challenge of these classes is to offer the children a happy environment where they can feel emotionally secure, and the teaching staff can create a harmonious atmosphere allowing them to learn by moving, manipulating, exchanging, making mistakes… playing. Creativity takes a central role as it enables the child to express him or herself and increase their ability to handle their emotions constructively. According to Albert Einstein ‘Play is the highest form of research’. &nbs...

  13. The Drosophila gene CheB42a is a novel modifier of Deg/ENaC channel function.

    Directory of Open Access Journals (Sweden)

    Yehuda Ben-Shahar

    2010-02-01

    Full Text Available Degenerin/epithelial Na(+ channels (DEG/ENaC represent a diverse family of voltage-insensitive cation channels whose functions include Na(+ transport across epithelia, mechanosensation, nociception, salt sensing, modification of neurotransmission, and detecting the neurotransmitter FMRFamide. We previously showed that the Drosophila melanogaster Deg/ENaC gene lounge lizard (llz is co-transcribed in an operon-like locus with another gene of unknown function, CheB42a. Because operons often encode proteins in the same biochemical or physiological pathway, we hypothesized that CHEB42A and LLZ might function together. Consistent with this hypothesis, we found both genes expressed in cells previously implicated in sensory functions during male courtship. Furthermore, when coexpressed, LLZ coprecipitated with CHEB42A, suggesting that the two proteins form a complex. Although LLZ expressed either alone or with CHEB42A did not generate ion channel currents, CHEB42A increased current amplitude of another DEG/ENaC protein whose ligand (protons is known, acid-sensing ion channel 1a (ASIC1a. We also found that CHEB42A was cleaved to generate a secreted protein, suggesting that CHEB42A may play an important role in the extracellular space. These data suggest that CHEB42A is a modulatory subunit for sensory-related Deg/ENaC signaling. These results are consistent with operon-like transcription of CheB42a and llz and explain the similar contributions of these genes to courtship behavior.

  14. Animals′ Role in Proper Behaviour: Cheŵa Women′s Instructions in South-Central Africa

    Directory of Open Access Journals (Sweden)

    Leslie F Zubieta

    2016-01-01

    Full Text Available The most common role of animals in the Cheŵa culture of south-central Africa is twofold: they are regarded as an important source of food, and they also provide raw materials for the creation of traditional medicines. Animals, however, also have a nuanced symbolic role that impacts the way people behave with each other by embodying cultural protocols of proper — and not so proper — behaviour. They appear repeatedly in storytelling and proverbs to reference qualities that people need to avoid or pursue and learn from the moral of the story in which animals interplay with each other, just as humans do. For example, someone who wants to prevent the consequences of greed is often advised to heed hyena stories and proverbs. My contribution elaborates on Brian Morris's instrumental work in south-central Africa, which has permitted us to elucidate the symbolism of certain animals and the perception of landscape for Indigenous populations in this region. I discuss some of the ways in which animals have been employed to teach and learn proper behaviour in a particular sacred ceremony of the Cheŵa people which takes place in celebration of womanhood: Chinamwali.

  15. Cloning, overexpression, purification, crystallization and preliminary X-ray analysis of CheY3, a response regulator that directly interacts with the flagellar ‘switch complex’ in Vibrio cholerae

    International Nuclear Information System (INIS)

    Khamrui, Susmita; Biswas, Maitree; Sen, Udayaditya; Dasgupta, Jhimli

    2010-01-01

    A chemotaxis response regulator CheY3 from V. cholerae has been cloned, overexpressed, purified and crystallized. The crystals of CheY3 diffracted to 1.86 Å resolution. Vibrio cholerae is the aetiological agent of the severe diarrhoeal disease cholera. This highly motile organism uses the processes of motility and chemotaxis to travel and colonize the intestinal epithelium. Chemotaxis in V. cholerae is far more complex than that in Escherichia coli or Salmonella typhimurium, with multiple paralogues of various chemotaxis genes. In contrast to the single copy of the chemotaxis response-regulator protein CheY in E. coli, V. cholerae contains four CheYs (CheY1–CheY4), of which CheY3 is primarily responsible for interacting with the flagellar motor protein FliM, which is one of the major constituents of the ‘switch complex’ in the flagellar motor. This interaction is the key step that controls flagellar rotation in response to environmental stimuli. CheY3 has been cloned, overexpressed and purified by Ni–NTA affinity chromatography followed by gel filtration. Crystals of CheY3 were grown in space group R3, with a calculated Matthews coefficient of 2.33 Å 3 Da −1 (47% solvent content) assuming the presence of one molecule per asymmetric unit

  16. A technician monitors the CHeX, a USMP-4 experiment which will be flown on STS-87, in the SSPF

    Science.gov (United States)

    1997-01-01

    United States Microgravity Payload-4 (USMP-4) experiments are prepared to be flown on Space Shuttle mission STS-87 in the Space Station Processing Facility at Kennedy Space Center (KSC). Here, a technician is monitoring the Confined Helium Experiment, or CHeX, that will use microgravity to study one of the basic influences on the behavior and properties of materials by using liquid helium confined between silicon disks. CHeX and several other experiments are scheduled for launch aboard STS-87 on Nov. 19 from KSC.

  17. La competitività delle imprse manufatturiere statunitensi. (The competitive position of U.S. manufacturing firms

    Directory of Open Access Journals (Sweden)

    R.E. LIPSEY

    2013-12-01

    Full Text Available Con l'alto valore costante del dollaro recentemente siè verificata la  preoccupazione per l' impatto a lungo termine sulla competitività dei produttori statunitensi. Questo studio distingue tra la competitività delle imprese statunitensi ed i vantaggi degli Stati Uniti come una base di produzione . Si è constatato che , anche se la quota statunitense del commercio mondiale è diminuita a partire dai primi anni 1970, la quota detenuta da imprese americane, al contrario di imprese che producono negli Stati Uniti, è aumentato. Si sostiene che le multinazionali statunitensi hanno superato il calo del vantaggio comparativo degli Stati Uniti come base di produzione spostando all'estero.With the continuing high value of the dollar there has recently been concern over the long-term impact on the competitiveness of US manufacturers. This study distinguishes between the competitiveness of US firms and the advantages of the United States as a production base. It is found that, although the US share of world trade has declined since the early 1970s, the share held by US firms, as opposed to firms producing in the United States, has increased. It is argued that US multinationals have overcome the decline in the comparative advantage of the United States as a production base by moving abroad.JEL: F23, L60

  18. Novel activation domain derived from Che-1 cofactor coupled with the artificial protein Jazz drives utrophin upregulation.

    Science.gov (United States)

    Desantis, Agata; Onori, Annalisa; Di Certo, Maria Grazia; Mattei, Elisabetta; Fanciulli, Maurizio; Passananti, Claudio; Corbi, Nicoletta

    2009-02-01

    Our aim is to upregulate the expression level of the dystrophin related gene utrophin in Duchenne muscular dystrophy, thus complementing the lack of dystrophin functions. To this end, we have engineered synthetic zinc finger based transcription factors. We have previously shown that the artificial three-zinc finger protein named Jazz fused with the Vp16 activation domain, is able to bind utrophin promoter A and to increase the endogenous level of utrophin in transgenic mice. Here, we report on an innovative artificial protein, named CJ7, that consists of Jazz DNA binding domain fused to a novel activation domain derived from the regulatory multivalent adaptor protein Che-1/AATF. This transcriptional activation domain is 100 amino acids in size and it is very powerful as compared to the Vp16 activation domain. We show that CJ7 protein efficiently promotes transcription and accumulation of the acetylated form of histone H3 on the genomic utrophin promoter locus.

  19. Review: Thomas Bierschenk and Eva Spies (eds, 50 Jahre Unabhängigkeit in Afrika: Kontinuitäten, Brüche, Perspektiven (2012

    Directory of Open Access Journals (Sweden)

    Geert Castryck

    2015-01-01

    Full Text Available Review of the edited volume: Thomas Bierschenk and Eva Spies (eds, 50 Jahre Unabhängigkeit in Afrika: Kontinuitäten, Brüche, Perspektiven, Cologne: Rüdiger Köppe Verlag, 2012, ISBN 9783896458292, 572 pages

  20. Producing Films, Producing Meanings: Some Theoretical Reflections

    Directory of Open Access Journals (Sweden)

    Giorgio Grignaffini

    2015-01-01

    Full Text Available L'articolo si pone l'obiettivo di stimolare una maggiore attenzione da parte della semiotica del cinema alle pratiche produttive e ai materiali preparatori del film, finora poco studiati rispetto alle dinamiche che i testi stessi attivano sulla ricezione. Tale proposta di allargamento del campo di ricerca, viene approfondita nelle sue premesse teoriche in due momenti. Dapprima viene contestualizzata rispetto alla pratica dell'analisi semiotica "tradizionale"; poi, utilizzando gli strumenti della sociosemiotica elaborata da Eric Landowski, in particolare sfruttando il concetto di "aggiustamento" sviluppato nel quadro della riflessione sulle modalità di interazione, vengono evidenziati campi di applicazione (ad es. il lavoro del regista con l’attore e possibili vantaggi euristici.

  1. Louis Blajan, Dottore in Medicina Veterinaria: Il dinamico veterinario che seppe traghettare l’Organizzazione Mondiale per la Sanità Animale (Office International des Épizooties: OIE nel mondo moderno

    Directory of Open Access Journals (Sweden)

    Anon.

    2010-03-01

    Full Text Available Nato il 10 aprile 1924 a Lahage (nell’Alta Garonna, in Francia, Louis Blajan si è spento lo scorso 10 febbraio 2010 a Mont-de-Marsan.Dopo aver frequentato il Lycée Pierre de Fermat di Tolosa, nel 1948 Louis completa gli studi presso la Scuola di Veterinaria di Tolosa. Nel 1949, si diploma all’Institut d’élevage et de médecine vétérinaire des pays tropicaux (IEMVT e dal 1949 al 1952 è nel territorio d’oltremare francese del Mali. Tornato in Francia, dal 1953 al 1968 Louis esercita come veterinario di Stato presso il Ministero dell’Agricoltura, responsabile per l’afta epizootica, la peste suina e la malattia di Newcastle, nonché come Presidente del Comitato consultivo per le malattie infettive. In seguito, viene nominato Ispettore capo veterinario e Responsabile per la politica di controllo delle frontiere.Nel 1952, Louis sposa Janine, moglie affezionata che lo appoggia con ardore in ogni fase della sua carriera e perde la vita in un incidente un mese prima che il marito vada in pensione nel 1990.Dal 1968 al 1977, Louis è Direttore tecnico di Cofranimex (Compagnie Française pour l’importation et l’exportation des animaux reproducteurs et leur semence e dal 1977 al 1978 riveste il ruolo di Direttore dell’Association pour le développement des techniques de l’élevage français (ADETEF.Louis entra a lavorare nell’Office International des Épizooties (oggi noto come Organizzazione Mondiale per la Sanità Animale o ‘OIE’ dove, dal 1978 al 1980, occupa la posizione di Direttore del Dipartimento tecnico. Due anni più tardi, nel 1980, viene eletto Direttore Generale, coronando il sogno di ogni professionista della medicina veterinaria e raggiungendo l’apice della propria carriera. Rieletto nel 1985, si ritira dalla vita lavorativa nel 1990.Durante gli anni in cui fu a capo dell’OIE, Louis seppe trasformare quella che all’epoca era una struttura antiquata in un’organizzazione internazionale moderna ed

  2. RESISTENCIA MICROBIANA EN EL CARDIOCENTRO ERNESTO CHE GUEVARA. ESTUDIO DE 5 AÑOS / Microbial resistance at the “Ernesto Che Guevara” Cardiology Hospital. A five year study

    Directory of Open Access Journals (Sweden)

    Nérida Rodríguez Oliva

    2009-06-01

    Full Text Available Introduction and Objectives: The appearance of nosocomial bacterial resistance represents a problem of growing concern because it largely affects the evolution of patients and the health resources devoted to it. The objective of this work was to determine the most common germs and their microbial resistance. Methods: A descriptive retrospective study was carried out analyzing the result of the isolation of germs from all type of secretions and from the blood cultures of a group ofpatients hospitalized at the Ernesto Che Guevara Cardiology Hospital in a five year period. Results: A total of 397 strains were isolated, 77 Staphylococcus aureus and 320 Enterobacteriaceae. The former presented 100% resistance to penicillin. The Staphylococcus sensitive to methicillin presented 4.9 % resistance to cotrimoxazole and gentamicin. The strains resistant to methicillin or oxacillin had a high resistance to gentamicin (87.5 % and ciprofloxacin (81.2 %, a medium resistance to cefazolin and oxacilline (20.5 %, and just 12.5 percent resistance to cotrimoxazole. Conclusions: the Staphylococcus aureus and the Enterobacteriaceae were the most common germs. The preoperative prophylaxis in these patients must not be done with cefazolin as a routine because the staphylococci resistant to methicillin or oxacillin have influence on other antimicrobials.

  3. Atomistic structural ensemble refinement reveals non-native structure stabilizes a sub-millisecond folding intermediate of CheY

    International Nuclear Information System (INIS)

    Shi, Jade; Schwantes, Christian; Bilsel, Osman

    2017-01-01

    The dynamics of globular proteins can be described in terms of transitions between a folded native state and less-populated intermediates, or excited states, which can play critical roles in both protein folding and function. Excited states are by definition transient species, and therefore are difficult to characterize using current experimental techniques. We report an atomistic model of the excited state ensemble of a stabilized mutant of an extensively studied flavodoxin fold protein CheY. We employed a hybrid simulation and experimental approach in which an aggregate 42 milliseconds of all-atom molecular dynamics were used as an informative prior for the structure of the excited state ensemble. The resulting prior was then refined against small-angle X-ray scattering (SAXS) data employing an established method (EROS). The most striking feature of the resulting excited state ensemble was an unstructured N-terminus stabilized by non-native contacts in a conformation that is topologically simpler than the native state. We then predict incisive single molecule FRET experiments, using these results, as a means of model validation. Our study demonstrates the paradigm of uniting simulation and experiment in a statistical model to study the structure of protein excited states and rationally design validating experiments.

  4. Genesis and classification of the soils developed from the sediments of the former Oleszek mill pond basin (the Chełmińskie Lakeland, N Poland / Geneza i pozycja systematyczna gleb wykształconych z osadów niecki dawnego stawu młyńskiego Oleszek (Pojezierze Chełmińskie

    Directory of Open Access Journals (Sweden)

    Mendyk Łukasz

    2015-03-01

    Full Text Available Budowa i funkcjonowanie młynów wodnych znacznie wpłynęły na przekształcenie środowiska przyrodniczego w ich otoczeniu, przede wszystkim na zmiany rzeźby terenu i warunków wodnych. Obszar badañ obejmuje nieckę dawnego stawu młyńskiego Oleszek w okolicach wsi Borówno, w zachodniej części Pojezierza Chełmińskiego, około 20 km na północny wschód od Torunia. Celem badañ było określenie genezy gleb wykształconych z osadów zakumulowanych w niecce dawnego stawu młyńskiego Oleszek. Pięć profili glebowych w transekcie o długości około 550 m zlokalizowanym wzdłuż Strugi Rychnowskiej stanowiącej oś podłużną niecki. Wszystkie przeanalizowane gleby zbudowane są z osadów wypełniających nieckę dawnego stawu młyńskiego. Gleby w opisywanej niecce powstały w wyniku wielu nakładających się procesów, takich jak: proces mułotwórczy, aluwialny, koluwialny oraz glejowy. Dwa z analizowanych profili glebowych (profile 3 i 4 spełniaj¹ kryteria wydzielania gleb organicznych limnowych typowych (Systematyka gleb Polski 2011. Jako pozycję systematyczną kolejnych dwóch gleb (profile 2 i 5 zaproponowano gleby mułowate. W związku z problemami klasyfikacyjnymi dotyczącymi tego typu gleb, przy opracowaniu aktualizacji Systematyki gleb Polski należałoby wprowadzić w typie gleb glejowych podtyp gleb mułowatych lub mułowato-glejowych, obejmuj¹cy gleby wytworzone z mineralno-organicznych utworów aluwialno-mułowych. Cztery wymienione powyżej profile zostały zaklasyfikowane jako Histosols (3 i 4 i Gleysols (2 i 5 według klasyfikacji WRB (2014. Jednostki glebowe wykształcone z osadów aluwialnych (mady wg SgP 2011 lub Fluvic Phaeozems wg WRB 2014 występują w proksymalnej części stawu (cofce.

  5. Substitution of the burning PRIOR SSB 10 for SSB7 in the Furnace 10 of the Company Major Ernesto Che Guevara

    Directory of Open Access Journals (Sweden)

    Ivett María Ramírez-Pérez

    2017-01-01

    Full Text Available One of the fundamental causes of massive destruction of chambers and vaults in the Furnace of Reduction at the Ernesto Che Guevara Factory is due to operate the combustion chambers with excess of contribution of heat, causing that the flame of very high temperature penetrates into the homes, affecting the throats of the chambers, the vaults, teeth and arms. The burners current are Prior SSB10. In this paper is demonstrated that the burning Prior SSB 10 have double productivity that the SSB 7 with the same quantity of air to the burner. It is evaluated the substitution of the burning Prior SSB 10 by SSB 7 on the operation of the Furnace of Reduction No. 10 at the Ernesto Che Guevara (ECG Factory. Demonstrating that the change not produce variations in the operation.

  6. Effects of Kapton Sample Cell Windows on the Detection Limit of Smectite: Implications for CheMin on the Mars Science Laboratory Mission

    Science.gov (United States)

    Achilles, C. N.; Ming, Douglas W.; Morris, R. V.; Blake, D. F.

    2012-01-01

    The CheMin instrument on the Mars Science Laboratory (MSL) rover Curiosity is an X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument capable of providing the mineralogical and chemical compositions of rocks and soils on the surface of Mars. CheMin uses a microfocus X-ray tube with a Co target, transmission geometry, and an energy-discriminating X-ray sensitive CCD to produce simultaneous 2-D XRD patterns and energy-dispersive X-ray histograms from powdered samples. CheMin has two different window materials used for sample cells -- Mylar and Kapton. Instrument details are provided elsewhere. Fe/Mg-smectite (e.g., nontronite) has been identified in Gale Crater, the MSL future landing site, by CRISM spectra. While large quantities of phyllosilicate minerals will be easily detected by CheMin, it is important to establish detection limits of such phases to understand capabilities and limitations of the instrument. A previous study indicated that the (001) peak of smectite at 15 Ang was detectable in a mixture of 1 wt.% smectite with olivine when Mylar is the window material for the sample cell. Complications arise when Kapton is the window material because Kapton itself also has a diffraction peak near 15 Ang (6.8 deg 2 Theta). This study presents results of mineral mixtures of smectite and olivine to determine smectite detection limits for Kapton sample cells. Because the intensity and position of the smectite (001) peak depends on the hydration state, we also analyzed mixtures with "hydrated" and "dehydrated"h smectite to examine the effects of hydration state on detection limits.

  7. Ordering at Si(111)/o-Si and Si(111)/SiO2 Interfaces

    DEFF Research Database (Denmark)

    Robinson, I. K.; Waskiewicz, W. K.; Tung, R. T.

    1986-01-01

    X-ray diffraction has been used to measure the intensity profile of the two-dimensional rods of scattering from a single interface buried inside a bulk material. In both Si(111)/a-Si and Si(111)/SiO2 examples there are features in the perpendicular-momentum-transfer dependence which are not expec...... are not expected from an ideal sharp interface. The diffraction profiles are explained by models with partially ordered layers extending into the amorphous region. In the Si(111)/a-Si case there is clear evidence of stacking faults which are attributed to residual 7×7 reconstruction....

  8. How to organize a maths e-book for vocational training schools

    Directory of Open Access Journals (Sweden)

    Damiano Trombini

    2016-04-01

    Full Text Available This paper aims to examine the educational planning in order to realize a maths e-book which might be used by teachers in vocational training schools. Along with the analysis of the advantages and the efficiency that a teacher could obtain adopting this type of multimedia technology, this paper will also analyze how to organize and insert into an e-book resources which allow to implement instructional strategies such as flipped classroom, cooperative learning, peer tutoring and all the aspects relating to the learning evaluation. Come organizzare un e-book per l’insegnamento della matematica nelle classi prime di istituti ad indirizzo professionaleLo scopo di questo saggio è quello di esaminare la progettazione didattica per la realizzazione di un e-book per l’insegnamento della matematica nelle classi prime di istituti secondari di secondo grado ad indirizzo professionale. Unitamente all’analisi dei vantaggi e dell’efficacia che un docente potrebbe ottenere nell’avvalersi di questo tipo di tecnologia multimediale, si analizzeranno le modalità di organizzazione e inserimento nell’e-book di risorse che permettano di implementare strategie didattiche come la flipped classroom, cooperative learning e il peer tutoring, nonché gli aspetti che riguardano la valutazione dell’apprendimento.

  9. Un uomo che valuta

    Directory of Open Access Journals (Sweden)

    Massimiliano Nicoli

    2015-12-01

    Full Text Available This article – written as a short story in the second-person narrative mode – focuses on the subjective, everyday experience of an individual concerned by some practices of evaluation. Through the telling of this concrete experience, it aims at giving substance to the idea that the practices of evaluation constitute an «environmental technology of government» typical of neoliberal governmentality as well as a self-disciplined technique of building one’s own «soul» as human capital.

  10. Department of Che

    African Journals Online (AJOL)

    USER

    2015-03-26

    Mar 26, 2015 ... watering, fish culturing and nursery of seedlings. Air is also very ... synthesized organic and inorganic fertilizers are made, synthesized pesticides and herbicides for ..... production and nutritional quality of grains. (Graham and ...

  11. E-learning e Università. Riflessioni tratte dalle interviste a quattro esperti italiani: Antonio Calvani, Luigi Guerra, Roberto Maragliano, Pier Cesare Rivoltella.

    Directory of Open Access Journals (Sweden)

    Laura Corazza

    2006-01-01

    Full Text Available Quattro esperti italiani di e-learning in ambito universitario hanno accettato di rispondere ad alcune domande su vantaggi e svantaggi, caratteristiche attuali e prospettive future di una nuova forma di didattica, l’e-learning, che richiede un ripensamento complessivo del modo di intendere l’apprendimento, lo sviluppo del sapere e la formazione della conoscenza.

  12. Structural studies of conformational changes of proteins upon phosphorylation: Structures of activated CheY, CheY-N16-FliM complex, and AAA + ATPase domain of NtrC1 in both inactive and active states

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seok-Yong [Univ. of California, Berkeley, CA (United States)

    2003-04-10

    Protein phosphorylation is a general mechanism for signal transduction as well as regulation of cellular function. Unlike phosphorylation in eukaryotic systems that uses Ser/Thr for the sites of modification, two-component signal transduction systems, which are prevalent in bacteria, archea, and lower eukaryotes, use an aspartate as the site of phosphorylation. Two-component systems comprise a histidine kinase and a receiver domain. The conformational change of the receiver domain upon phosphorylation leads to signal transfer to the downstream target, a process that had not been understood well at the molecular level. The transient nature of the phospho-Asp bond had made structural studies difficult. The discovery of an excellent analogue for acylphosphate, BeF3-, enabled structural study of activated receiver domains. The structure of activated Chemotaxis protein Y (CheY) was determined both by NMR spectroscopy and X-ray crystallography. These structures revealed the molecular basis of the conformational change that is coupled to phosphorylation. Phosphorylation of the conserved Asp residue in the active site allows hydrogen bonding of the T87 Oγ to phospho-aspartate, which in turn leads to the rotation of Y106 into the ''in'' position (termed Y-T coupling). The structure of activated CheY complexed with the 16 N-terminal residues of FliM (N16-FliM), its target, was also determined by X-ray crystallography and confirmed the proposed mechanism of activation (Y-T coupling). First, N16-FliM binds to the region on CheY that undergoes a significant conformational change. Second, the ''in'' position of Y106 presents a better binding surface for FliM because the sidechain of Y106 in the inactive form of CheY (''out'' position) sterically interferes with binding of N16-FliM. In addition to confirmation of Y-T coupling, the structure of the activated CheY-N16-FliM complex suggested that the

  13. Nouvelles fonctions de l'agriculture et dynamiques des exploitations: une analyse chorématique dans les monts d'Ardèche

    Directory of Open Access Journals (Sweden)

    Muriel Bonin

    2001-06-01

    Full Text Available Les modèles spatiaux sont utilisés pour l'analyse des trajectoires d'exploitations agricoles pour mettre en évidence les liens entre les transformations socio-économiques et les dynamiques de territoires. Les traits de dynamiques spatiales sont identifiés et utilisés pour analyser l'impact de l'introduction de l'agritourisme dans les exploitations dans le Parc naturel régional des monts d'Ardèche.

  14. Automatización del control del cálculo de extracciones en la mina de la empresa niquelera Ernesto Che Guevara

    Directory of Open Access Journals (Sweden)

    Arístides A. Legrá-Lobaina

    2010-03-01

    Full Text Available En el artículo se muestran los elementos fundamentales de un algoritmo cuyo objetivo es establecer el contenido y el orden de los procedimientos necesarios para realizar el control del cálculo de extracciones en la mina de la empresa Ernesto Che Guevara que explota, a cielo abierto, yacimientos lateríticos ferroniquelíferos en la región de Moa, Cuba. Asimismo se presenta el diseño de los diálogos informáticos que han automatizado el algoritmo en la aplicación informática Tierra.

  15. A 36,000-Year-Old Volcanic Eruption Depicted in the Chauvet-Pont d’Arc Cave (Ardèche, France)?

    Science.gov (United States)

    Nomade, Sébastien; Genty, Dominique; Sasco, Romain; Scao, Vincent; Féruglio, Valérie; Baffier, Dominique; Guillou, Hervé; Bourdier, Camille; Valladas, Hélène; Reigner, Edouard; Debard, Evelyne; Pastre, Jean–François; Geneste, Jean-Michel

    2016-01-01

    Among the paintings and engravings found in the Chauvet-Pont d’Arc cave (Ardèche, France), several peculiar spray-shape signs have been previously described in the Megaloceros Gallery. Here we document the occurrence of strombolian volcanic activity located 35 km northwest of the cave, and visible from the hills above the cave entrance. The volcanic eruptions were dated, using 40Ar/39Ar, between 29 ± 10 ka and 35 ± 8 ka (2σ), which overlaps with the 14C AMS and thermoluminescence ages of the first Aurignacian occupations of the cave in the Megaloceros Gallery. Our work provides the first evidence of an intense volcanic activity between 40 and 30 ka in the Bas-Vivarais region, and it is very likely that Humans living in the Ardèche river area witnessed one or several eruptions. We propose that the spray-shape signs found in the Chauvet-Pont d’Arc cave could be the oldest known depiction of a volcanic eruption, predating by more than 34 ka the description by Pliny the Younger of the Vesuvius eruption (AD 79) and by 28 ka the Çatalhöyük mural discovered in central Turkey. PMID:26745626

  16. A 36,000-Year-Old Volcanic Eruption Depicted in the Chauvet-Pont d'Arc Cave (Ardèche, France)?

    Science.gov (United States)

    Nomade, Sébastien; Genty, Dominique; Sasco, Romain; Scao, Vincent; Féruglio, Valérie; Baffier, Dominique; Guillou, Hervé; Bourdier, Camille; Valladas, Hélène; Reigner, Edouard; Debard, Evelyne; Pastre, Jean-François; Geneste, Jean-Michel

    2016-01-01

    Among the paintings and engravings found in the Chauvet-Pont d'Arc cave (Ardèche, France), several peculiar spray-shape signs have been previously described in the Megaloceros Gallery. Here we document the occurrence of strombolian volcanic activity located 35 km northwest of the cave, and visible from the hills above the cave entrance. The volcanic eruptions were dated, using 40Ar/39Ar, between 29 ± 10 ka and 35 ± 8 ka (2σ), which overlaps with the 14C AMS and thermoluminescence ages of the first Aurignacian occupations of the cave in the Megaloceros Gallery. Our work provides the first evidence of an intense volcanic activity between 40 and 30 ka in the Bas-Vivarais region, and it is very likely that Humans living in the Ardèche river area witnessed one or several eruptions. We propose that the spray-shape signs found in the Chauvet-Pont d'Arc cave could be the oldest known depiction of a volcanic eruption, predating by more than 34 ka the description by Pliny the Younger of the Vesuvius eruption (AD 79) and by 28 ka the Çatalhöyük mural discovered in central Turkey.

  17. SI units in radiology

    Energy Technology Data Exchange (ETDEWEB)

    Iyer, P S [Bhabha Atomic Research Centre, Bombay (India). Div. of Radiation Protection

    1978-11-01

    The proposal of the International Commission on Radiation Units and Measurements that the special units of radiation and radioactivity-roentgen, rad, rem and curie-be replaced by the International System (SI) of Units has been accepted by international bodies. This paper reviews the resons for introducing the new units and their features. The relation between the special units and the corresponding SI units is discussed with examples. In spite of anticipated difficulties, the commission recommends a smooth and efficient changeover to the SI units in ten years.

  18. Evita Perón y el Che Guevara: De la historia a la construcción literaria del mito biográfico

    Directory of Open Access Journals (Sweden)

    Cecilia López Badano

    2014-06-01

    Full Text Available Eva Perón y el Che Guevara son dos de las figuras paradigmáticas argentinas, conocidas internacionalmente a través no sólo de sus vidas, que pueden reconstruirse a partir de documentos históricos, sino por el mito nacional - e internacional - que la muerte temprana ha configurado con ambos mediante la ayuda de la literatura y el cine, expandiendo ficcionalmente el matiz revolucionario de su accionar. El presente texto se propone, en consecuencia, dar cuenta de esas "capas" ficcionales que conforman la construcción estética de los dos mitos biográficos e inciden en la evaluación de sus protagonistas reales, modelando la percepción de ambos, particularmente, la considerada por el gran público más que por los especialistas.

  19. Microstructure and Mechanical Property of SiCf/SiC and Cf/SiC Composites

    International Nuclear Information System (INIS)

    Lee, S P; Cho, K S; Lee, H U; Lee, J K; Bae, D S; Byun, J H

    2011-01-01

    The mechanical properties of SiC based composites reinforced with different types of fabrics have been investigated, in conjunction with the detailed analyses of their microstructures. The thermal shock properties of SiC f /SiC composites were also examined. All composites showed a dense morphology in the matrix region. Carbon coated PW-SiC f /SiC composites had a good fracture energy, even if their strength was lower than that of PW-C f /SiC composites. SiC f /SiC composites represented a great reduction of flexural strength at the thermal shock temperature difference of 300 deg. C.

  20. Environmental analysis of natural gas life cycle; Analisi ambientale del ciclo di vita del gas naturale

    Energy Technology Data Exchange (ETDEWEB)

    Riva, A.; D' Angelosante, S.; Trebeschi, C. [Snam SpA, Rome (Italy)

    2000-12-01

    Life Cycle Assessment is a method aimed at identifying the environmental effects connected with a given product, process or activity during its whole life cycle. The evaluation of published studies and the application of the method to electricity production with fossil fuels, by using data from published databases and data collected by the gas industry, demonstrate the importance and difficulties to have reliable and updated data required for a significant life cycle assessment. The results show that the environmental advantages of natural gas over the other fossil fuels in the final use stage increase still further if the whole life cycle of the fuels, from production to final consumption, is taken into account. [Italian] L'analisi del ciclo di vita e' una metodologia che consente di identificare gli effetti ambientali associati ad un prodotto, processo o attivita' lungo il loro ciclo di vita. La valutazione di studi pubblicati e l'applicazione della metodologia alla produzione di energia elettrica da combustibili fossili, utilizzando dati provenienti da banche dati di letteratura e raccolti dall'industria del gas, dimostrano l'importanza e la difficolta' di avere a disposizione dati affidabili ed aggiornati, necessari per un'analisi significativa del ciclo di vita. I risultati mostrano che i vantaggi ambientali del gas naturale rispetto agli altri combustibili fossili nella fase di utilizzo finale, aumentano ulteriormente se si considera l'intero ciclo di vita dei diversi combustibili, dalla produzione al consumo finale.

  1. First-Principles Studies of Functionalized Si(111) in Air and in Water

    Science.gov (United States)

    Li, Yan; Galli, Giulia

    2011-03-01

    We have investigated structural, electronic and vibrational properties of hydrogen and methyl-terminated Si(111) surfaces both in air and in contact with water, by combining density functional theory and many-body perturbation theory within the GW approximations. The computed surface dipole moments for both H-Si(111) and CH3-Si(111) surfaces were found to be consistent with measured electron affinities (EAs), and can be explain by simple electronegative trends. While GW self-energy corrections greatly improve the absolute values of EAs, the EA difference of the two surfaces remains overestimated by about 0.3 eV. The variations in CH3 frequencies, e.g. the umbrella mode and CH stretching mode, for the surface in air and water are also well reproduced by our calculations. The influence exerted by the adsorption of water molecules on the hydrophobic H-Si(111) and CH3-(111) surfaces, in particular, on the EAs and the surface vibrational frequencies will be discussed and compared with recent experiments. This work was funded by NSF under Grant No. CHE-0802907.

  2. Analisi della qualità in biblioteca: la soluzione SiMonLib™@CASPUR

    Directory of Open Access Journals (Sweden)

    Ugo Contino

    2011-12-01

    Full Text Available ItLa raccolta periodica di dati e l’analisi delle performance, in un’ottica di valutazione della Qualità del Servizio, sono sicuramente elementi rilevanti per coloro che s’interessino della gestione di una biblioteca o di un sistema bibliotecario. Modi sempre più efficienti e ottimizzati per gestire specifiche campagne di raccolta dati non possono prescindere dall’uso di strumenti in ambito ICT, soprattutto per far fronte ai non banali problemi logistico organizzativi che simili attività di raccolta dati possono comportare. In quest’ambito merita sicuramente menzione SimonLib™, un software prodotto dalla XSystems di Cagliari e pensato per gestire i processi di raccolta dati e misura della qualità in biblioteca, sia essa singola o appartenente ad un sistema. Conscio delle potenzialità offerte da questa piattaforma, il CASPUR ha sottoscritto recentemente un accordo con XSystems per offrire SimonLib alla comunità delle biblioteche italiane, sia pubbliche che private. Il servizio offerto, SiMonLib@CASPUR, installato all’interno di un’infrastruttura di server virtuali (Service Cloud presso il CED del CASPUR, prevede l’accesso in piattaforma in modalità SaaS (Software as a Service, che garantisce le piene funzionalità del servizio ad un costo notevolmente contenuto.EnLibrarians and managers of a library system have to face with relevant problems when service quality measurement in libraries is concerned. The usage of ICT based solutions for measurement campaign, data assessment and analysis, seems to be an efficient way to cope with those issues. In the past few years a software company from Cagliari (XSystems has introduced a complete, web based software solution for quality measurement in a library or a library system, called SimonLib™, that can easily address the typical technical and logistic obstacles of complex service quality measurement process. In order to offer a reliable service based on SimonLib software for

  3. Changes of serum levels of prealbumin (PAB), cholinesterase (CHE), total bile acid (TBA) and ALT as related to the severity of inflammatory process and hepatic fibrosis in patients with chronic virus B hepatitis

    International Nuclear Information System (INIS)

    Chi Xiaoxia; Chen Jianxiong; Xiong Ying

    2005-01-01

    Objective: To study the correlationship between the serum levels of PAB, CHE, TBA, ALT and the severity of the disease process in patients with chronic virus B hepatitis. Methods: Serum levels of PAB, CHE, ALT (with biochemical methods) and TBA (with RIA) were examined in 93 patients with biopsy proven virus B hepatitis and 46 controls. Results: The 93 patients were of two groups: a less advanced group (n=51) and a more advanced group (n=42). Serum TBA, ALT levels were significnatly higher and serum PAB, CHE levels were significantly lower in the more advanced group than those in the less advanced group (P 0 to s 4 . Changes of levels of ALT were of no regular pattern, but serum levels of TBA regularly increased and levels of PAB, CHE regularly decreased as the fibrosis grading proceeded from s 0 to s 4 and the differences between the levels in s 4 and any other grading were significant (P<0.01). Conclusion: Combined determination of these serum markers might reflect the degree of inflammatory process and hepatic fibrosis in patients with virus B hepatitis, leading to earlier detection of cirrhosis. (authors)

  4. Interfacial characterization of CVI-SiC/SiC composites

    International Nuclear Information System (INIS)

    Yang, W.; Kohyama, A.; Noda, T.; Katoh, Y.; Hinoki, T.; Araki, H.; Yu, J.

    2002-01-01

    The mechanical properties of the interfaces of two families of chemical vapor infiltration SiC/SiC composites, advanced Tyranno-SA and Hi-Nicalon fibers reinforced SiC/SiC composites with various carbon and SiC/C interlayers, were investigated by single fiber push-out/push-back tests. Interfacial debonding and fibers sliding mainly occurred adjacent to the first carbon layer on the fibers. The interfacial debonding strengths and frictional stresses for both Tyranno-SA/SiC and Hi-Nicalon/SiC composites were correlated with the first carbon layer thickness. Tyranno-SA/SiC composites exhibited much larger interfacial frictional stresses compared to Hi-Nicalon/SiC composites. This was assumed to be mainly contributed by the rather rough surface of the Tyranno-SA fiber

  5. Sub-barrier fusion of Si+Si systems

    Science.gov (United States)

    Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Bourgin, D.; Čolović, P.; Corradi, L.; Courtin, S.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Urbani, M.; Szilner, S.; Zhang, G. L.

    2017-11-01

    The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC) calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3- excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.

  6. Sub-barrier fusion of Si+Si systems

    Directory of Open Access Journals (Sweden)

    Colucci G.

    2017-01-01

    Full Text Available The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3− excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.

  7. Conditions of concentration and composition of suspended load in the Vistula River between Wyszogród and Chełmno

    Science.gov (United States)

    Kaszubski, Michal

    2014-05-01

    The main objective of the study is to explain causes of variations of concentration, particle size distribution and composition of suspended load in the riverbed of the lower Vistula between Wyszogród and Chełmno. The study was conducted in seven bridge cross-sections (three above and four below the Włocławek reservoir). In each cross-section, three water samples were collected in the characteristic parts of the riverbed. Since July 2012 fifteen measurement series were carried out. During each measurement series 22 samples of water were collected. In each sample the overall concentration of suspended load, the proportion of the organic matter and particle size distribution of the mineral fraction were measured. Variation of concentration and characteristics of suspended load were studied both in the cross-sections of the Vistula riverbed and along its longitudinal profile. The study focus primarily on determining the qualitative and quantitative variation in the properties of suspended load in the cross-sections located in different morphological riverbed type, various level of its hydrotechnical management, including the operation on the Włocławek reservoir, and the diversity of the water flow conditions. The author tested the correlation occurring between the size of suspended load concentration as well as the flow rate and flow velocity at the water sampling sites. Moreover, the author determined the effect of morphological variation of the Vistula riverbed (the riverbed depth and the location of points of collecting water samples relative to the riverbed mesoforms) on the concentration size, composition structure and the particle size distribution of suspended load. Measurement sessions were chosen in such a way as to cover the widest possible spectrum of the water flow conditions in the riverbed of the Vistula. In addition to the low and medium flow the variability in concentration during flood flows of various types (ice jam, snowmelt and rainfall) were

  8. Photoluminescence of Er-doped Si-SiO2 and Al-Si-SiO2 sputtered thin films

    International Nuclear Information System (INIS)

    Rozo, C.; Fonseca, L.F.; Jaque, D.; Sole, J.Garcia

    2008-01-01

    Er-doped Si-SiO 2 and Al-Si-SiO 2 films have been deposited by rf-sputtering being annealed afterwards. Annealing behavior of the Er 3+ : 4 I 13/2 → 4 I 15/2 emission of Er-doped Si-SiO 2 yields a maximum intensity for annealing at 700-800 deg. C. 4 I 13/2 → 4 I 15/2 peak emission for Er-doped Al-Si-SiO 2 at 1525 nm is shifted from that for Er-doped Si-SiO 2 at 1530 nm and the bandwidth increases from 29 to 42 nm. 4 I 13/2 → 4 I 15/2 emission decays present a fast decaying component related to Er ions coupled to Si nanoparticles, defects, or other ions, and a slow decaying component related to isolated Er ions. Excitation wavelength dependence and excitation power dependence for the 4 I 13/2 → 4 I 15/2 emission correspond with energy transfer from Si nanoparticles. Populating of the 4 I 11/2 level in Er-doped Si-SiO 2 involves branching and energy transfer upconversion involving two or more Er ions. Addition of Al reduces the populating of this level to an energy transfer upconversion involving two ions

  9. The CheMin XRD on the Mars Science Laboratory Rover Curiosity: Construction, Operation, and Quantitative Mineralogical Results from the Surface of Mars

    Science.gov (United States)

    Blake, David F.

    2015-01-01

    The Mars Science Laboratory mission was launched from Cape Canaveral, Florida on Nov. 26, 2011 and landed in Gale crater, Mars on Aug. 6, 2012. MSL's mission is to identify and characterize ancient "habitable" environments on Mars. MSL's precision landing system placed the Curiosity rover within 2 km of the center of its 20 X 6 km landing ellipse, next to Gale's central mound, a 5,000 meter high pile of laminated sediment which may contain 1 billion years of Mars history. Curiosity carries with it a full suite of analytical instruments, including the CheMin X-ray diffractometer, the first XRD flown in space. CheMin is essentially a transmission X-ray pinhole camera. A fine-focus Co source and collimator transmits a 50µm beam through a powdered sample held between X-ray transparent plastic windows. The sample holder is shaken by a piezoelectric actuator such that the powder flows like a liquid, each grain passing in random orientation through the beam over time. Forward-diffracted and fluoresced X-ray photons from the sample are detected by an X-ray sensitive Charge Coupled Device (CCD) operated in single photon counting mode. When operated in this way, both the x,y position and the energy of each photon are detected. The resulting energy-selected Co Kalpha Debye-Scherrer pattern is used to determine the identities and amounts of minerals present via Rietveld refinement, and a histogram of all X-ray events constitutes an X-ray fluorescence analysis of the sample.The key role that definitive mineralogy plays in understanding the Martian surface is a consequence of the fact that minerals are thermodynamic phases, having known and specific ranges of temperature, pressure and composition within which they are stable. More than simple compositional analysis, definitive mineralogical analysis can provide information about pressure/temperature conditions of formation, past climate, water activity and the like. Definitive mineralogical analyses are necessary to establish

  10. Rock shelter occupation during isotopic stage 5: level D of the site of Payre (Ardèche, France. Territorial organisation and intra-site activities

    Directory of Open Access Journals (Sweden)

    Moncel, Marie-Hélène

    2007-06-01

    Full Text Available This paper presents the results obtained from an interdisciplinary study of the level D archaeological assemblages from Payre (Ardèche, France. This site is dated to the final of OIS 6 and the beginning of OIS 5. The combined analysis of the lithic and faunal assemblages accumulated and their management “into” and “out of” the site gives a better understanding of the behaviour of the Neanderthal groups that inhabited it. This study has allowed us to correlate the territorial exploitation for game hunting and for raw material procurement, within the context of seasonal short term occupations probably during the end of autumn and the beginning of winter.  

    Este artículo presenta los resultados obtenidos a través del estudio multidisciplinar del registro arqueológico del nivel D del yacimiento de Payre (Ardèche, Francia datado entre el final del OIS 6 y el comienzo del OIS 5. El análisis conjunto de la industria lítica y de los restos óseos recuperados en el yacimiento y de la gestión de dichos recursos dentro y fuera de él, ha hecho posible la comprensión de los comportamientos humanos de los grupos neandertales que lo ocuparon. Dicho estudio nos ha permitido poner en relación el tipo de explotación del territorio de caza y de captación de materias primas, dentro del marco de ocupaciones estacionales de corta duración desarrolladas probablemente entre el final del otoño y el principio del invierno.  

  11. SiCloud

    DEFF Research Database (Denmark)

    Jiang, Cathy Y.; Devore, Peter T.S.; Lonappan, Cejo Konuparamban

    2017-01-01

    The silicon photonics industry is projected to be a multibillion dollar industry driven by the growth of data centers. In this work, we present an interactive online tool for silicon photonics. Silicon Photonics Cloud (SiCCloud.org) is an easy to use instructional tool for optical properties...

  12. SI: The Stellar Imager

    Science.gov (United States)

    Carpenter, Kenneth G.; Schrijver, Carolus J.; Karovska, Margarita

    2006-01-01

    The ultra-sharp images of the Stellar Imager (SI) will revolutionize our view of many dynamic astrophysical processes: The 0.1 milliarcsec resolution of this deep-space telescope will transform point sources into extended sources, and simple snapshots into spellbinding evolving views. SI s science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI s prime goal is to enable long-term forecasting of solar activity and the space weather that it drives in support of the Living With a Star program in the Exploration Era by imaging a sample of magnetically active stars with enough resolution to map their evolving dynamo patterns and their internal flows. By exploring the Universe at ultra-high resolution, SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magnetohydrodynamically controlled structures and processes in the Universe.

  13. U-Mo/Al-Si interaction: Influence of Si concentration

    International Nuclear Information System (INIS)

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

    2010-01-01

    Within the framework of the development of low enriched nuclear fuels for research reactors, U-Mo/Al is the most promising option that has however to be optimised. Indeed at the U-Mo/Al interfaces between U-Mo particles and the Al matrix, an interaction layer grows under irradiation inducing an unacceptable fuel swelling. Adding silicon in limited content into the Al matrix has clearly improved the in-pile fuel behaviour. This breakthrough is attributed to an U-Mo/Al-Si protective layer around U-Mo particles appeared during fuel manufacturing. In this work, the evolution of the microstructure and composition of this protective layer with increasing Si concentrations in the Al matrix has been investigated. Conclusions are based on the characterization at the micrometer scale (X-ray diffraction and energy dispersive spectroscopy) of U-Mo7/Al-Si diffusion couples obtained by thermal annealing at 450 deg. C. Two types of interaction layers have been evidenced depending on the Si content in the Al-Si alloy: the threshold value is found at about 5 wt.% but obviously evolves with temperature. It has been shown that for Si concentrations ranging from 2 to 10 wt.%, the U-Mo7/Al-Si interaction is bi-layered and the Si-rich part is located close to the Al-Si for low Si concentrations (below 5 wt.%) and close to the U-Mo for higher Si concentrations. For Si weight fraction in the Al alloy lower than 5 wt.%, the Si-rich sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2 Al 20 , when the other sub-layer (close to U-Mo) is silicon free and made of UAl 3 and U 6 Mo 4 Al 43 . For Si weight concentrations above 5 wt.%, the Si-rich part becomes U 3 (Si, Al) 5 + U(Al, Si) 3 (close to U-Mo) and the other sub-layer (close to Al-Si) consists of U(Al, Si) 3 + UMo 2 Al 20 . On the basis of these results and of a literature survey, a scheme is proposed to explain the formation of different types of ILs between U-Mo and Al-Si alloys (i.e. different protective layers).

  14. Nonvolatile field effect transistors based on protons and Si/SiO2Si structures

    International Nuclear Information System (INIS)

    Warren, W.L.; Vanheusden, K.; Fleetwood, D.M.; Schwank, J.R.; Winokur, P.S.; Knoll, M.G.; Devine, R.A.B.

    1997-01-01

    Recently, the authors have demonstrated that annealing Si/SiO 2 /Si structures in a hydrogen containing ambient introduces mobile H + ions into the buried SiO 2 layer. Changes in the H + spatial distribution within the SiO 2 layer were electrically monitored by current-voltage (I-V) measurements. The ability to directly probe reversible protonic motion in Si/SiO 2 /Si structures makes this an exemplar system to explore the physics and chemistry of hydrogen in the technologically relevant Si/SiO 2 structure. In this work, they illustrate that this effect can be used as the basis for a programmable nonvolatile field effect transistor (NVFET) memory that may compete with other Si-based memory devices. The power of this novel device is its simplicity; it is based upon standard Si/SiO 2 /Si technology and forming gas annealing, a common treatment used in integrated circuit processing. They also briefly discuss the effects of radiation on its retention properties

  15. Gd-Ni-Si system

    International Nuclear Information System (INIS)

    Bodak, O.I.; Shvets, A.F.

    1983-01-01

    By X-ray phase analysis method isothermal cross section of phase diagram of the Gd-Ni-Si system at 870 K is studied. The existence of nine previously known compounds (GdNisub(6.72)Sisub(6.28), GdNi 10 Si 2 , GdNi 5 Si 3 , GdNi 4 Si, GdNi 2 Si 2 , GdNiSi 3 , GdNiSi 2 , Gd 3 Ni 6 Si 2 and GdNiSi) is confirmed and three new compounds (GdNisub(0.2)Sisub(1.8), Gdsub(2)Nisub(1-0.8)Sisub(1-1.2), Gd 5 NiSi 4 ) are found. On the base of Gd 2 Si 3 compound up to 0.15 at. Ni fractions, an interstitial solid solution is formed up to 0.25 at Ni fractions dissolution continues of substitution type. The Gd-Ni-Si system is similar to the Y-Ni-Si system

  16. Si-to-Si wafer bonding using evaporated glass

    DEFF Research Database (Denmark)

    Reus, Roger De; Lindahl, M.

    1997-01-01

    Anodic bonding of Si to Si four inch wafers using evaporated glass was performed in air at temperatures ranging from 300°C to 450°C. Although annealing of Si/glass structures around 340°C for 15 minutes eliminates stress, the bonded wafer pairs exhibit compressive stress. Pull testing revealed...

  17. Oblique roughness replication in strained SiGe/Si multilayers

    NARCIS (Netherlands)

    Holy, V.; Darhuber, A.A.; Stangl, J.; Bauer, G.; Nützel, J.-F.; Abstreiter, G.

    1998-01-01

    The replication of the interface roughness in SiGe/Si multilayers grown on miscut Si(001) substrates has been studied by means of x-ray reflectivity reciprocal space mapping. The interface profiles were found to be highly correlated and the direction of the maximal replication was inclined with

  18. LA DIAGNOSI DELLE COMPETENZE LINGUISTICHE IN UN CONTESTO MULTILINGUE: UN PROCESSO CONTINUO CHE FAVORISCE L’INSEGNAMENTO E L’APPRENDIMENTO INDIVIDUALIZZATO

    Directory of Open Access Journals (Sweden)

    Drorit Lengyel

    2011-07-01

    Full Text Available Il presente studio affronta il problema della valutazione diagnostica delle competenze linguistiche in contesti educativi multilingui, con particolare attenzione ai bisogni dei bambini e degli adolescenti immigrati. Vengono brevemente esposti gli obiettivi, le funzioni e i principi della valutazione diagnostica e della valutazione formativa considerate parte integrante di una educazione linguistica continua che prevede un insegnamento-apprendimento individualizzato. Sul piano teorico le procedure della valutazione diagnostica delle competenze linguistiche in contesti multilingui fanno riferimento all’apprendimento delle lingue inteso come attività socio-culturale.     Language diagnostics in multilingual settings with respect to continuous procedures as accompaniment of individualized learning and teaching   This study provides an introduction to language diagnostics in multilingual educational settings, with particular reference to the needs of children and adolescents from migrant backgrounds. It summarises the objectives and functions of language diagnostics and the principles that govern diagnostics including formative assessment, considered to be an integral part of continuous language education that emphasises individualised teaching and learning. From a theoretical perspective, diagnostic procedures in multilingual settings treat language learning as a socio-cultural activity.  

  19. Evaluation of the Addition liquor with high ammonia and Carbon Dioxide contentin the still 208 of the “Comandante Che Guevara” industry (ECG

    Directory of Open Access Journals (Sweden)

    María Elena Magaña-Haynes

    2015-12-01

    Full Text Available Adding fresh liquor through the 5th ring in still 208 of distilling liquor product (liquor obtained as a result of ammonium carbonate leaching of lateritic ore in the “Comandante Che Guevara” industry, were evaluated with the objective of reducing the dissolved nickel content of the effluent there from, as well as to improve the characteristics of the nickel carbonate which is delivered to the calcinations process. For the development of the survey, the same methodology used in 2001 for the test was applied. The results showed that by adding fresh liquor, it is possible to reduce the dissolved nickel content at the exit of the distillation column, so that the need for precipitation is minimized, thereby reducing the consumption of reagents and the and the cost for their acquisition. It was possible to corroborate the relationship between the content of NH3 at the discharge and the nickel dissolved therein appreciating that to achieve these results it is necessary to maintain the ammonia in the discharge between 1,0-1,8 g/L. The carbonate obtained in the column where liquor is added with high CO2 and NH3 reached high values of this last element in its composition and to the extent that increased sulphur content decreased. It was also seen an increase in the size of the coarse carbonates particles, which will influence in a decrease of energy consumption.

  20. Applications of Si/SiGe heterostructures to CMOS devices

    International Nuclear Information System (INIS)

    Sidek, R.M.

    1999-03-01

    For more than two decades, advances in MOSFETs used in CMOS VLSI applications have been made through scaling to ever smaller dimensions for higher packing density, faster circuit speed and lower power dissipation. As scaling now approaches nanometer regime, the challenge for further scaling becomes greater in terms of technology as well as device reliability. This work presents an alternative approach whereby non-selectively grown Si/SiGe heterostructure system is used to improve device performance or to relax the technological challenge. SiGe is considered to be of great potential because of its promising properties and its compatibility with Si, the present mainstream material in microelectronics. The advantages of introducing strained SiGe in CMOS technology are examined through two types of device structure. A novel structure has been fabricated in which strained SiGe is incorporated in the source/drain of P-MOSFETs. Several advantages of the Si/SiGe source/drain P-MOSFETs over Si devices are experimentally, demonstrated for the first time. These include reduction in off-state leakage and punchthrough susceptibility, degradation of parasitic bipolar transistor (PBT) action, suppression of CMOS latchup and suppression of PBT-induced breakdown. The improvements due to the Si/SiGe heterojunction are supported by numerical simulations. The second device structure makes use of Si/SiGe heterostructure as a buried channel to enhance the hole mobility of P-MOSFETs. The increase in the hole mobility will benefit the circuit speed and device packing density. Novel fabrication processes have been developed to integrate non-selective Si/SiGe MBE layers into self-aligned PMOS and CMOS processes based on Si substrate. Low temperature processes have been employed including the use of low-pressure chemical vapor deposition oxide and plasma anodic oxide. Low field mobilities, μ 0 are extracted from the transfer characteristics, Id-Vg of SiGe channel P-MOSFETs with various Ge

  1. Electronic states at Si-SiO2 interface introduced by implantation of Si in thermal SiO2

    International Nuclear Information System (INIS)

    Kalnitsky, A.; Poindexter, E.H.; Caplan, P.J.

    1990-01-01

    Interface traps due to excess Si introduced into the Si-SiO 2 system by ion implantation are investigated. Implanted oxides are shown to have interface traps at or slightly above the Si conduction band edge with densities proportional to the density of off-stoichiometric Si at the Si-SiO 2 interface. Diluted oxygen annealing is shown to result in physical separation of interface traps and equilibrium substrate electrons, demonstrating that ''interface'' states are located within a 0.5 nm thick layer of SiO 2 . Possible charge trapping mechanisms are discussed and the effect of these traps on MOS transistor characteristics is described using a sheet charge model. (author)

  2. Reliability implications of defects in high temperature annealed Si/SiO2/Si structures

    International Nuclear Information System (INIS)

    Warren, W.L.; Fleetwood, D.M.; Shaneyfelt, M.R.; Winokur, P.S.; Devine, R.A.B.; Mathiot, D.; Wilson, I.H.; Xu, J.B.

    1994-01-01

    High-temperature post-oxidation annealing of poly-Si/SiO 2 /Si structures such as metal-oxide-semiconductor capacitors and metal-oxide-semiconductor field effect transistors is known to result in enhanced radiation sensitivity, increased 1/f noise, and low field breakdown. The authors have studied the origins of these effects from a spectroscopic standpoint using electron paramagnetic resonance (EPR) and atomic force microscopy. One result of high temperature annealing is the generation of three types of paramagnetic defect centers, two of which are associated with the oxide close to the Si/SiO 2 interface (oxygen-vacancy centers) and the third with the bulk Si substrate (oxygen-related donors). In all three cases, the origin of the defects may be attributed to out-diffusion of O from the SiO 2 network into the Si substrate with associated reduction of the oxide. The authors present a straightforward model for the interfacial region which assumes the driving force for O out-diffusion is the chemical potential difference of the O in the two phases (SiO 2 and the Si substrate). Experimental evidence is provided to show that enhanced hole trapping and interface-trap and border-trap generation in irradiated high-temperature annealed Si/SiO 2 /Si systems are all related either directly, or indirectly, to the presence of oxygen vacancies

  3. Strained Si/SiGe MOS transistor model

    Directory of Open Access Journals (Sweden)

    Tatjana Pešić-Brđanin

    2009-06-01

    Full Text Available In this paper we describe a new model of surfacechannel strained-Si/SiGe MOSFET based on the extension of non-quasi-static (NQS circuit model previously derived for bulk-Si devices. Basic equations of the NQS model have been modified to account for the new physical parameters of strained-Si and relaxed-SiGe layers. From the comparisons with measurements, it is shown that a modified NQS MOS including steady-state self heating can accurately predict DC characteristics of Strained Silicon MOSFETs.

  4. Decision making information systems and data base management; Applicazioni dei sistemi di supporto alle decisioni manageriali in un ente fortemente decentrato. Sviluppo di un prototipo per la valutazione di nuovi progetti

    Energy Technology Data Exchange (ETDEWEB)

    Minelle, F [Rome, Univ. ` La Sapienza` (Italy). Fac. di Scienze Matematiche, Fisiche e Naturali; Di Marco, R A [ENEA, Rome (Italy). Funzione Centrale Informatica; Belli, A

    1997-01-01

    con essi; e di rpesentare un prototipo di tali sistemi. Da una fase preliminare di analisi dell`Ente e dei suoi Sistemi Informativi, volta a capire quali problematiche potessero essere piu` efficacemente supportate con sistemi di questo tipo, si afronta una di esse: la valutazione di nuovi progetti, individuando i parametri, o le grandezze chiave, che influenzano e determinano la decisione. Si descrivono, poi, i modelli, ricavati da questi ultimi, che permettono all`utente, tramite una semplice rappresentazione dei risultati, di valutare i vantaggi e gli svantaggi di un nuovo progetto. Dai modelli, dall`analisi dei dati ad essi necessari e dai requisiti di semplicita` e facilita` d`uso dell`interfaccia utente, si e` realizzato un prototipo. A questo scopo si e` seguito il modelllo di Sprague e Carlson che prevede una Base di Dati, una Base di Modelli e un Sistema Software.

  5. Grandi Eventi: indicatori di classificazione e incidenza sui sistemi urbani

    Directory of Open Access Journals (Sweden)

    Giuseppe Mazzeo

    2008-08-01

    Full Text Available I grandi eventi sono ritenuti una opportunità per le città in quanto sono uno straordinario catalizzatore di investimenti mirati alla trasformazione della città. L’azione dei grandi eventi non è confinata solo nel periodo di svolgimento dell’evento stesso ma si estende ad un periodo molto più ampio, prima e, soprattutto, dopo il suo termine. Nell’organizzazione delle manifestazioni più recenti le trasformazioni urbane hanno interessato in modo sempre maggiore parti già in precedenza urbanizzate, al punto che l’evento diviene l’occasione per trasformare la città costruita e per modificarne il profilo. Il paper approfondisce l’argomento della classificazione degli eventi e del loro impatto sul sistema urbano sviluppandosi in tre parti. Nella prima si analizzano due tipologie di grandi eventi (le esposizioni internazionali e i giochi olimpici con l’obiettivo di pervenire ad una definizione condivisa. Nella seconda parte si identificano i più importanti fattori ed indicatori per l’analisi di questa specifica categoria di avvenimenti. Infine, nella terza parte, si approfondiscono i fattori connessi all’impatto sul sistema urbano e all’organizzazione della sua mobilità. In particolare, viene approfondito il concetto di “effetto pulsar”, ossia gli effetti moltiplicativi sulla evoluzione urbana dipendenti dalla organizzazione di eventi multipli in parallelo o in sequenza. Uno degli elementi più negativi connessi alla organizzazione di un grande evento è la dispersione nel tempo dei benefici acquisiti grazie ad esso; per evitare ciò è necessario che l’evento sia seguito da politiche strategiche continue in modo da preservare i vantaggi acquisiti.

  6. High-performance a -Si/c-Si heterojunction photoelectrodes for photoelectrochemical oxygen and hydrogen evolution

    KAUST Repository

    Wang, Hsin Ping; Sun, Ke; Noh, Sun Young; Kargar, Alireza; Tsai, Meng Lin; Huang, Ming Yi; Wang, Deli; He, Jr-Hau

    2015-01-01

    Amorphous Si (a-Si)/crystalline Si (c-Si) heterojunction (SiHJ) can serve as highly efficient and robust photoelectrodes for solar fuel generation. Low carrier recombination in the photoelectrodes leads to high photocurrents and photovoltages

  7. Irradiation effect on Nite-SiC/SiC composites

    International Nuclear Information System (INIS)

    Hinoki, T.; Choi, Y.B.; Kohyama, A.; Ozawa, K.

    2007-01-01

    Full text of publication follows: Silicon carbide (SiC) and SiC composites are significantly attractive materials for nuclear application in particular due to exceptional low radioactivity, excellent high temperature mechanical properties and chemical stability. Despite of the excellent potential of SiC/SiC composites, the prospect of industrialization has not been clear mainly due to the low productivity and the high material cost. Chemical vapor infiltration (CVI) method can produce the excellent SiC/SiC composites with highly crystalline and excellent mechanical properties. It has been reported that the high purity SiC/SiC composites reinforced with highly crystalline fibers and fabricated by CVI method is very stable to neutron irradiation. However the production cost is high and it is difficult to fabricate thick and dense composites by CVI method. The novel processing called Nano-powder Infiltration and Transient Eutectic Phase (NITE) Processing has been developed based on the liquid phase sintering (LPS) process modification. The NITE processing can achieve both the excellent material quality and the low processing cost. The productivity of the processing is also excellent, and various kinds of shape and size of SiC/SiC composites can be produced by the NITE processing. The NITE processing can form highly crystalline matrix, which is requirement for nuclear application. The objective of this work is to understand irradiation effect of the NITESiC/SiC composites. The SiC/SiC composites used were reinforced with high purity SiC fibers, Tyranno TM SA and fabricated by the NITE method. The NITE-SiC/SiC composite bars and reference monolithic SiC bars fabricated by CVI and NITE were irradiated at up to 1.0 dpa and 600-1000 deg. C at JMTR, Japan. Mechanical properties of non-irradiated and irradiated NITESiC/ SiC composites bars were evaluated by tensile tests. Monolithic SiC bars were evaluated by flexural tests. The fracture surface was examined by SEM. Ultimate

  8. Carbon redistribution and precipitation in high temperature ion-implanted strained Si/SiGe/Si multi-layered structures

    DEFF Research Database (Denmark)

    Gaiduk, Peter; Hansen, John Lundsgaard; Nylandsted Larsen, Arne

    2014-01-01

    Graphical abstract Carbon depth profiles after high temperature implantation in strained Si/SiGe/Si multilayered system and induced structural defects.......Graphical abstract Carbon depth profiles after high temperature implantation in strained Si/SiGe/Si multilayered system and induced structural defects....

  9. Tassi di cambio fluttuanti, deprezzamento valutario e domanda effettiva (Floating exchange rates, currency depreciation and actual demand

    Directory of Open Access Journals (Sweden)

    Julio López

    2012-04-01

    Full Text Available Il presente articolo esamina i vantaggi relativi dei tassi di cambio fluttuanti nei confronti di un regime di tassi di cambio a parità rigidamente ancorate (hard peg, ponendo particolare enfasi sulle implicazioni per la domanda effettiva. In particolare, esso valuta se un deprezzamento della valuta abbia un effetto benefico sulla domanda aggregata e dunque sull’occupazione. Si sostiene che tale questione è centrale per il principio della domanda effettiva, e che l’idea che un deprezzamento valutario sia in grado di stabilizzare la domanda effettiva, equivale in larga misura a sostenere che la flessibilità (verso il basso dei salari nominali (e reali possa assicurare la piena occupazione. Coerentemente con ciò, viene analizzata la relazione tra la flessibilità verso il basso dei salari e la domanda effettiva, e viene valutata criticamente (dal punto di vista sia teorico sia empirico l’ipotesi che la flessibilità del tasso di cambio possa avere proprietà stabilizzanti quando si tenga conto di shock esogeni di varia natura. L’articolo si chiude con brevi deduzioni di teoria e di politica economiche.   This paper examines the relative advantages of floating exchange rates against a system of exchange rates for the same rigidly anchored (hard peg, with particular emphasis on the implications for effective demand. In particular, it will assess whether a currency depreciation has a beneficial effect on aggregate demand and hence employment. It is argued that this issue is central to the principle of effective demand, and that the idea that a currency depreciation is able to stabilize the effective demand, is equivalent to a large extent to support that flexibility (down in nominal wages (and real to ensure full employment. Consistent with this, we analyze the relationship between the downward flexibility of wages and effective demand, and is critically evaluated (in terms of both theoretical and empirical hypothesis that the flexibility

  10. Mineralogy, provenance, and diagenesis of a potassic basaltic sandstone on Mars: CheMin X-ray diffraction of the Windjana sample (Kimberley area, Gale Crater)

    International Nuclear Information System (INIS)

    Treiman, Allan H.; Bish, David L.; Chipera, Steve J.; Blake, David F.

    2015-01-01

    The Windjana drill sample, a sandstone of the Dillinger member (Kimberley formation, Gale Crater, Mars), was analyzed by CheMin X-ray diffraction (XRD) in the MSL Curiosity rover. From Rietveld refinements of its XRD pattern, Windjana contains the following: sanidine (21% weight, ~Or 95 ); augite (20%); magnetite (12%); pigeonite; olivine; plagioclase; amorphous and smectitic material (~25%); and percent levels of others including ilmenite, fluorapatite, and bassanite. From mass balance on the Alpha Proton X-ray Spectrometer (APXS) chemical analysis, the amorphous material is Fe rich with nearly no other cations—like ferrihydrite. The Windjana sample shows little alteration and was likely cemented by its magnetite and ferrihydrite. From ChemCam Laser-Induced Breakdown Spectrometer (LIBS) chemical analyses, Windjana is representative of the Dillinger and Mount Remarkable members of the Kimberley formation. LIBS data suggest that the Kimberley sediments include at least three chemical components. The most K-rich targets have 5.6% K 2 O, ~1.8 times that of Windjana, implying a sediment component with >40% sanidine, e.g., a trachyte. A second component is rich in mafic minerals, with little feldspar (like a shergottite). A third component is richer in plagioclase and in Na 2 O, and is likely to be basaltic. The K-rich sediment component is consistent with APXS and ChemCam observations of K-rich rocks elsewhere in Gale Crater. The source of this sediment component was likely volcanic. Finally, the presence of sediment from many igneous sources, in concert with Curiosity's identifications of other igneous materials (e.g., mugearite), implies that the northern rim of Gale Crater exposes a diverse igneous complex, at least as diverse as that found in similar-age terranes on Earth.

  11. Issues relating to classification of colluvial soils in young morainic areas (Chełmno and Brodnica Lake District, northern Poland

    Directory of Open Access Journals (Sweden)

    Świtoniak Marcin

    2015-06-01

    Full Text Available Colluvial soils (in Polish: gleby deluwialne are an important part of the soil cover in young morainic landscapes of northern Poland. They evolved as a result of the accumulation of eroded material at the foot of the slopes and bottoms of closed depressions. The aim of this study was to determine the systematic position of colluvial soils commonly found in the Chełmno and Brodnica Lake District, northern Poland. Ten soil pits located in different types of landscapes were selected for testing soil properties. The colluvial material is characterized by diversified properties: thickness, particle-size distribution, organic carbon content, color, pH, and base saturation. As a result, the investigated soils represent broad spectrum of typological units according to Polish Soil Classification (2011. Some of them contain epipedons mollic and meet the criteria of colluvial chernozemic soils. They were found mainly on buried black earths in areas with small slope inclinations. Many pedons contain pale colored acidic colluvial material with low base saturation and low organic carbon content and must be classified as other types: arenosols (in Polish: arenosole or rusty soils (in Polish: gleby rdzawe. These soils occur mostly in areas with intensive relief and overlay the different soil types, including rusty soil and organic soils. They are formed as a result of soils lessivés and rusty soils truncation. An introduction of the additional units of “proper colluvial soils” which have epipedon ochric, and “rusty-colluvial soils” with endopedon sideric to the next edition of Polish Soil Classification would enable a more precise expression of the genesis of these soils in the type rank. Moreover, the definition of chernozemic colluvial soils could be extended to colluvial soils with umbric horizon. Classifying soils derived from colluvial material as soils of other types leads to the disappearance of this units on maps and underestimation of the

  12. Defecography of rectal wall prolapse conditions; Defecografia nelle malattie parietali del retto da prolasso

    Energy Technology Data Exchange (ETDEWEB)

    Salzano, A.; Muto, M.; De Rosa, A. [Azienda Sanitaria di Rilievo Nazionale A. Cardarelli, Naples (Italy). Servizio di Neuroradiologia; Ginolfi, F.; Carbone, M.; Amodio, F.; Rossi, E. [Naples Univ. Federico 2. (Italy). Ist. di Scienze Radiologiche; Tuccillo, M. [Azienda Sanitaria di Rilirvo Nazionale A. Cardarelli, Naples (Italy). 2. Servizio di Radiologia

    1999-06-01

    Pelvic floor and rectal prolapse conditions have greatly benefited by new imaging and instrumental diagnostic approaches, and especially defecography, for both pathophysiological interpretation and differential diagnosis. The authors investigated the efficacy of defecography in the assessment of rectal prolapse, and in particular the role of videproctography in diagnosis such dynamic disorders. The dynamic changes of ampulla are well depicted by videoproctography, which showed anorectum normalization and spontaneous reduction of invagination after intussusception. Defecography exhibited good capabilities in showing rectal wall function abnormalities. Finally, some features of videoproctography such as low radiation dose, non-invasiveness and ease of execution, make the examination acceptable to patients with anorectal disorders and for the follow-up of rectal prolapse. [Italian] Le malattie del pavimento pelvico e dei prolassi del retto hanno tratto numerosi vantaggi da nuovi approcci di diagnostica per immagini e strumentali, specialmente dall'esame defecografico, sia nell'interpretazione fisiopatologica che nella diagnostica differenziale dei disordini anorettali. Scopo del lavoro: valutare l'efficacia della metodica defecografica nel riconoscimento delle malattie da prolasso del retto e in particolare il ruolo svolto dalla videoproctografia nella documentazione diagnostica e nel definire i principali elementi semeiologici riscontrabili in tali malattie in modo dinamico. Le fasi dinamiche della valutazione morfologica e posizionale dell'ampolla rettale sono ben evidenti nella viedeoproctografia, che documenta dopo l'intussuscezione la normalizzazione del complesso anorettale e la riduzione spontanea dell'invaginazione parietale. In questo studio si sottolineano le possibilita' diagnostiche della defecografia integrata da videoproctografia nel riconoscimento delle malattie parietali funzionali del retto e alcune peculiarita

  13. Synthesis and characterization of laminated Si/SiC composites

    Science.gov (United States)

    Naga, Salma M.; Kenawy, Sayed H.; Awaad, Mohamed; Abd El-Wahab, Hamada S.; Greil, Peter; Abadir, Magdi F.

    2012-01-01

    Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results. PMID:25685404

  14. Structure of MnSi on SiC(0001)

    Science.gov (United States)

    Meynell, S. A.; Spitzig, A.; Edwards, B.; Robertson, M. D.; Kalliecharan, D.; Kreplak, L.; Monchesky, T. L.

    2016-11-01

    We report on the growth and magnetoresistance of MnSi films grown on SiC(0001) by molecular beam epitaxy. The growth resulted in a textured MnSi(111) film with a predominantly [1 1 ¯0 ] MnSi (111 )∥[11 2 ¯0 ] SiC(0001) epitaxial relationship, as demonstrated by transmission electron microscopy, reflection high energy electron diffraction, and atomic force microscopy. The 500 ∘C temperature required to crystallize the film leads to a dewetting of the MnSi layer. Although the sign of the lattice mismatch suggested the films would be under compressive stress, the films acquire an in-plane tensile strain likely driven by the difference in thermal expansion coefficients between the film and substrate during annealing. As a result, the magnetoresistive response demonstrates that the films possess a hard-axis out-of-plane magnetocrystalline anisotropy.

  15. Synthesis and characterization of laminated Si/SiC composites

    Directory of Open Access Journals (Sweden)

    Salma M. Naga

    2013-01-01

    Full Text Available Laminated Si/SiC ceramics were synthesized from porous preforms of biogenous carbon impregnated with Si slurry at a temperature of 1500 °C for 2 h. Due to the capillarity infiltration with Si, both intrinsic micro- and macrostructure in the carbon preform were retained within the final ceramics. The SEM micrographs indicate that the final material exhibits a distinguished laminar structure with successive Si/SiC layers. The produced composites show weight gain of ≈5% after heat treatment in air at 1300 °C for 50 h. The produced bodies could be used as high temperature gas filters as indicated from the permeability results.

  16. Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiNx/SiNy multilayers

    International Nuclear Information System (INIS)

    Jiang, Xiaofan; Ma, Zhongyuan; Yang, Huafeng; Yu, Jie; Wang, Wen; Zhang, Wenping; Li, Wei; Xu, Jun; Xu, Ling; Chen, Kunji; Huang, Xinfan; Feng, Duan

    2014-01-01

    Adding a resistive switching functionality to a silicon microelectronic chip is a new challenge in materials research. Here, we demonstrate that unipolar and electrode-independent resistive switching effects can be realized in the annealed Si-rich SiN x /SiN y multilayers with high on/off ratio of 10 9 . High resolution transmission electron microscopy reveals that for the high resistance state broken pathways composed of discrete nanocrystalline silicon (nc-Si) exist in the Si nitride multilayers. While for the low resistance state the discrete nc-Si regions is connected, forming continuous nc-Si pathways. Based on the analysis of the temperature dependent I-V characteristics and HRTEM photos, we found that the break-and-bridge evolution of nc-Si pathway is the origin of resistive switching memory behavior. Our findings provide insights into the mechanism of the resistive switching behavior in nc-Si films, opening a way for it to be utilized as a material in Si-based memories.

  17. Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiNx/SiNy multilayers

    Science.gov (United States)

    Jiang, Xiaofan; Ma, Zhongyuan; Yang, Huafeng; Yu, Jie; Wang, Wen; Zhang, Wenping; Li, Wei; Xu, Jun; Xu, Ling; Chen, Kunji; Huang, Xinfan; Feng, Duan

    2014-09-01

    Adding a resistive switching functionality to a silicon microelectronic chip is a new challenge in materials research. Here, we demonstrate that unipolar and electrode-independent resistive switching effects can be realized in the annealed Si-rich SiNx/SiNy multilayers with high on/off ratio of 109. High resolution transmission electron microscopy reveals that for the high resistance state broken pathways composed of discrete nanocrystalline silicon (nc-Si) exist in the Si nitride multilayers. While for the low resistance state the discrete nc-Si regions is connected, forming continuous nc-Si pathways. Based on the analysis of the temperature dependent I-V characteristics and HRTEM photos, we found that the break-and-bridge evolution of nc-Si pathway is the origin of resistive switching memory behavior. Our findings provide insights into the mechanism of the resistive switching behavior in nc-Si films, opening a way for it to be utilized as a material in Si-based memories.

  18. Study of Si/Si, Si/SiO2, and metal-oxide-semiconductor (MOS) using positrons

    International Nuclear Information System (INIS)

    Leung, To Chi.

    1991-01-01

    A variable-energy positron beam is used to study Si/Si, Si/SiO 2 , and metal-oxide-semiconductor (MOS) structures. The capability of depth resolution and the remarkable sensitivity to defects have made the positron annihilation technique a unique tool in detecting open-volume defects in the newly innovated low temperature (300C) molecular-beam-epitaxy (MBE) Si/Si. These two features of the positron beam have further shown its potential role in the study of the Si/SiO 2 . Distinct annihilation characteristics has been observed at the interface and has been studied as a function of the sample growth conditions, annealing (in vacuum), and hydrogen exposure. The MOS structure provides an effective way to study the electrical properties of the Si/SiO 2 interface as a function of applied bias voltage. The annihilation characteristics show a large change as the device condition is changed from accumulation to inversion. The effect of forming gas (FG) anneal is studied using positron annihilation and the result is compared with capacitance-voltage (C-V) measurements. The reduction in the number of interface states is found correlated with the changes in the positron spectra. The present study shows the importance of the positron annihilation technique as a non-contact, non-destructive, and depth-sensitive characterization tool to study the Si-related systems, in particular, the Si/SiO 2 interface which is of crucial importance in semiconductor technology, and fundamental understanding of the defects responsible for degradation of the electrical properties

  19. Positron annihilation at the Si/SiO2 interface

    International Nuclear Information System (INIS)

    Leung, T.C.; Weinberg, Z.A.; Asoka-Kumar, P.; Nielsen, B.; Rubloff, G.W.; Lynn, K.G.

    1992-01-01

    Variable-energy positron annihilation depth-profiling has been applied to the study of the Si/SiO 2 interface in Al-gate metal-oxide-semiconductor (MOS) structures. For both n- and p-type silicon under conditions of negative gate bias, the positron annihilation S-factor characteristic of the interface (S int ) is substantially modified. Temperature and annealing behavior, combined with known MOS physics, suggest strongly that S int depends directly on holes at interface states or traps at the Si/SiO 2 interface

  20. Formation of Si/Ge/Si heterostructures with quantum dots

    International Nuclear Information System (INIS)

    Zinov'ev, V.A.; Dvurechenskij, A.V.; Novikov, P.L.

    2003-01-01

    It is present the Monte Carlo simulation of epitaxial embedding of faceted three-dimensional Ge islands (quantum dots) in a Si matrix. Under a Si flux these islands expand and undergo a shape change (from pyramidal to drop-like shape). The main expansion occurs at initial stage of embedding in Si (deposition of 1-2 monolayers). This change is controlled by surface diffusion. The shape of island can be preserved when one uses the higher Si fluxes. The reason of island conservation lies in blocking of Ge surface diffusion [ru

  1. Origini Concettuali di Errori che si Riscontrano Nel Confrontare Numeri Decimali e Frazioni=Conceptual Sources of Difficulties Concerning the Ordering of Decimal Numbers and the Comparison of Fractions.

    Science.gov (United States)

    Bonotto, C.

    1993-01-01

    Examined fifth-grade students' survey responses to investigate incorrect rules that derive from children's efforts to interpret decimals as integers or as fractions. Regarding fractions, difficulties arise because only the whole-part approach to fractions is presented in elementary school. (Author/MDH)

  2. 32Si dating of sediments

    International Nuclear Information System (INIS)

    Morgenstern, U.

    2006-01-01

    Useful tools for determining absolute ages of sediments deposited within the last c. 100 years include 210 Pb, 137 Cs, and bomb radiocarbon. Cosmogenic 32 Si, with a half life of c. 140 years, can be applied in the age range 30-1000 years and is ideally suited for this time period. Detection of 32 Si is, however, very difficult due to its extremely low natural specific activity, and the vast excess of stable silicon (i.e. low 32 Si/Si ratio). 23 refs

  3. Architecture of buried reverse fault zone in the sedimentary basin: A case study from the Hong-Che Fault Zone of the Junggar Basin

    Science.gov (United States)

    Liu, Yin; Wu, Kongyou; Wang, Xi; Liu, Bo; Guo, Jianxun; Du, Yannan

    2017-12-01

    It is widely accepted that the faults can act as the conduits or the barrier for oil and gas migration. Years of studies suggested that the internal architecture of a fault zone is complicated and composed of distinct components with different physical features, which can highly influence the migration of oil and gas along the fault. The field observation is the most useful methods of observing the fault zone architecture, however, in the petroleum exploration, what should be concerned is the buried faults in the sedimentary basin. Meanwhile, most of the studies put more attention on the strike-slip or normal faults, but the architecture of the reverse faults attracts less attention. In order to solve these questions, the Hong-Che Fault Zone in the northwest margin of the Junggar Basin, Xinjiang Province, is chosen for an example. Combining with the seismic data, well logs and drill core data, we put forward a comprehensive method to recognize the internal architectures of buried faults. High-precision seismic data reflect that the fault zone shows up as a disturbed seismic reflection belt. Four types of well logs, which are sensitive to the fractures, and a comprehensive discriminated parameter, named fault zone index are used in identifying the fault zone architecture. Drill core provides a direct way to identify different components of the fault zone, the fault core is composed of breccia, gouge, and serpentinized or foliated fault rocks and the damage zone develops multiphase of fractures, which are usually cemented. Based on the recognition results, we found that there is an obvious positive relationship between the width of the fault zone and the displacement, and the power-law relationship also exists between the width of the fault core and damage zone. The width of the damage zone in the hanging wall is not apparently larger than that in the footwall in the reverse fault, showing different characteristics with the normal fault. This study provides a

  4. SiC/SiC Cladding Materials Properties Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Snead, Mary A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Katoh, Yutai [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Koyanagi, Takaaki [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Singh, Gyanender P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    When a new class of material is considered for a nuclear core structure, the in-pile performance is usually assessed based on multi-physics modeling in coordination with experiments. This report aims to provide data for the mechanical and physical properties and environmental resistance of silicon carbide (SiC) fiber–reinforced SiC matrix (SiC/SiC) composites for use in modeling for their application as accidenttolerant fuel cladding for light water reactors (LWRs). The properties are specific for tube geometry, although many properties can be predicted from planar specimen data. This report presents various properties, including mechanical properties, thermal properties, chemical stability under normal and offnormal operation conditions, hermeticity, and irradiation resistance. Table S.1 summarizes those properties mainly for nuclear-grade SiC/SiC composites fabricated via chemical vapor infiltration (CVI). While most of the important properties are available, this work found that data for the in-pile hydrothermal corrosion resistance of SiC materials and for thermal properties of tube materials are lacking for evaluation of SiC-based cladding for LWR applications.

  5. Oscillations in the fusion of the Si + Si systems

    International Nuclear Information System (INIS)

    Aguilera R, E.F.; Kolata, J.J.; DeYoung, P.A.; Vega, J.J.

    1986-02-01

    Excitation functions for the yields of all the residual nuclei from the 28 Si + 28,30 and 30 Si + 30 Si reactions have been measured via the γ-ray technique for center of mass energies in the region within one and two times the Coulomb barrier.Thirteen elements were identified for the first reaction and ten for the other two. While no structure is shown by the data for the 28 + 28 Si reaction, we have found evidence for intermediate width structure in the 2α and the αpn channels in 28 Si + 30 Si and for broad structure in the total fusion cross sections for 30 Si + 30 Si. Calculations using a barrier penetration model with one free parameter reproduce the experimental results quite well. Evaporation model calculations indicate that the individual structure of the nuclei involved in the respective decay chains might have an important influence upon the deexcitation process at the energies relevant to our experiments. (Author)

  6. Joining of SiC ceramics and SiC/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Rabin, B.H. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1996-08-01

    This project has successfully developed a practical and reliable method for fabricating SiC ceramic-ceramic joints. This joining method will permit the use of SiC-based ceramics in a variety of elevated temperature fossil energy applications. The technique is based on a reaction bonding approach that provides joint interlayers compatible with SiC, and excellent joint mechanical properties at temperatures exceeding 1000{degrees}C. Recent emphasis has been given to technology transfer activities, and several collaborative research efforts are in progress. Investigations are focusing on applying the joining method to sintered {alpha}-SiC and fiber-reinforced SiC/SiC composites for use in applications such as heat exchangers, radiant burners and gas turbine components.

  7. Tailoring of SiC nanoprecipitates formed in Si

    Energy Technology Data Exchange (ETDEWEB)

    Velisa, G., E-mail: gihan.velisa@cea.fr [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 077125 Magurele (Romania); Trocellier, P. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Thomé, L. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, UMR8609, Bât. 108, 91405 Orsay (France); Vaubaillon, S. [CEA, INSTN, UEPTN, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Miro, S.; Serruys, Y.; Bordas, É. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France); Meslin, E. [CEA, DEN, Service de Recherches de Métallurgie Physique, F-91191 Gif-sur-Yvette (France); Mylonas, S. [Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, UMR8609, Bât. 108, 91405 Orsay (France); Coulon, P.E. [Ecole Polytechnique, Laboratoire des Solides Irradiés, CEA/DSM/IRAMIS-CNRS, 91128 Palaiseau Cedex (France); Leprêtre, F.; Pilz, A.; Beck, L. [CEA, DEN, Service de Recherches de Métallurgie Physique, Laboratoire JANNUS, F-91191 Gif-sur-Yvette (France)

    2013-07-15

    The SiC synthesis through single-beam of C{sup +}, and simultaneous-dual-beam of C{sup +} and Si{sup +} ion implantations into a Si substrate heated at 550 °C has been studied by means of three complementary analytical techniques: nuclear reaction analysis (NRA), Raman, and transmission electron microscopy (TEM). It is shown that a broad distribution of SiC nanoprecipitates is directly formed after simultaneous-dual-beam (520-keV C{sup +} and 890-keV Si{sup +}) and single-beam (520-keV C{sup +}) ion implantations. Their shape appear as spherical (average size ∼4–5 nm) and they are in epitaxial relationship with the silicon matrix.

  8. An investigation into the 2 Si(p,gamma)30P reaction

    International Nuclear Information System (INIS)

    Oberholzer, P.

    1978-01-01

    In the experiment reported here, information was obtained on the energy levels of 30 P by means of the 2 Si(p,gamma) 30 P-reaction. The experimental work was done with two accelerators, the 3 MV Van de Graaff- accelerator of the AEB and the 2,5 MV Van de Graaff-accelerator of the P.U. for C.H.E. A 60 cm 3 - and a 80 cm 3 Ge(Li)-detector were used. The excitation curve of the 2 Si + p-reaction was measured in the 1,3 - 2,0 MeV energy range. In order to calculate proton energies which were more accurate, the Q-value of the reaction was redetermined. The gamma decay of 12 resonances in the energy range l,l - 1,9 MeV was studied. The branching ratios of 25 bound levels in 30 P were determined, as well as the excitation energy and branching ratios of two new bound levels. A different value for the excitation energy of one bound level was found. The mean lifetimes of 12 bound levels were measured by means of the doppler shift attenuation method and the results were compared to those of other groups using different methods of lifetime measurement. Spin and parity assignments based on Weisskopf estimates were made for a number of resonance states, as well as for one new bound state. The experimental results were compared with the results of two models

  9. SI units in radiation protection

    International Nuclear Information System (INIS)

    Jain, V.K.; Soman, S.D.

    1978-01-01

    International System of Units abbreviated as SI units has been adopted by most of the countries of the world. Following this development, the implementation of SI units has become mandatory with a transition period of about ten years. Some of the journals have already adopted the SI units and any material sent for publication to them must use only these. International Commission on Radiation Units and Measurement (ICRU) published letters in several journals including Physics in Medicine and Biology, Health Physics, British Journal of Radiology, etc. outlining the latest recommendations on SI units to elicit the reactions of scientists in the general field of radiological sciences. Reactions to the letters were numerous as can be seen in the correspondence columns of these journals for the last few years and ranged from great misgivings and apprehension to support and appreciation. SI units have also been the subject of editorial comments in several journals. On the basis of a survey of this literature, it may be said that there was general agreement on the long term advantage of SI units inspite of some practical difficulties in their use particularly in the initial stages. This report presents a review of SI units in radiological sciences with a view to familiarize the users with the new units in terms of the old. A time table for the gradual changeover to the SI units is also outlined. (auth.)

  10. Oscillations in the fusion of the Si + Si systems; Oscilaciones en la fusion de sistemas de Si + Si

    Energy Technology Data Exchange (ETDEWEB)

    Aguilera R, E F; Kolata, J J; DeYoung, P A; Vega, J J [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1986-02-15

    Excitation functions for the yields of all the residual nuclei from the {sup 28} Si + {sup 28,30} and {sup 30} Si + {sup 30} Si reactions have been measured via the {gamma}-ray technique for center of mass energies in the region within one and two times the Coulomb barrier.Thirteen elements were identified for the first reaction and ten for the other two. While no structure is shown by the data for the {sup 28} + {sup 28} Si reaction, we have found evidence for intermediate width structure in the 2{alpha} and the {alpha}pn channels in {sup 28} Si + {sup 30} Si and for broad structure in the total fusion cross sections for {sup 30} Si + {sup 30} Si. Calculations using a barrier penetration model with one free parameter reproduce the experimental results quite well. Evaporation model calculations indicate that the individual structure of the nuclei involved in the respective decay chains might have an important influence upon the deexcitation process at the energies relevant to our experiments. (Author)

  11. Synthesis and structural property of Si nanosheets connected to Si nanowires using MnCl{sub 2}/Si powder source

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Erchao [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Ueki, Akiko [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Meng, Xiang [Graduate School of Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Suzuki, Hiroaki [Graduate School of Engineering, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Itahara, Hiroshi [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Tatsuoka, Hirokazu, E-mail: tatsuoka.hirokazu@shizuoka.ac.jp [Graduate School of Integrated Science and Technology, Shizuoka University, 3-5-1 Johuku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan)

    2016-08-15

    Graphical abstract: Si nanosheets connected to Si nanowires synthesized using a MnCl{sub 2}/Si powder source with an Au catalyst avoid the use of air-sensitive SiH{sub 4} or SiCl{sub 4}. It was evident from these structural features of the nanosheets (leaf blade) with nanowires (petiole) that the nanosheets were formed by the twin-plane reentrant-edge mechanism. The feature of the observed lattice fringes of the Si(111) nanosheets was clearly explained by the interference with the extra diffraction spots that arose due to the reciprocal lattice streaking effect. - Highlights: • New Si nanosheets connected to Si nanowires were synthesized using MnCl{sub 2}/Si powders. • The synthesis method has benefits in terms of avoiding air sensitive SiH{sub 4} or SiCl{sub 4}. • Structural property and electron diffraction of the Si nanosheets were clarified. • Odd lattice fringes of the Si nanosheets observed by HRTEM were clearly explained. - Abstract: Si nanosheets connected to Si nanowires were synthesized using a MnCl{sub 2}/Si powder source with an Au catalyst. The synthesis method has benefits in terms of avoiding conventionally used air-sensitive SiH{sub 4} or SiCl{sub 4}. The existence of the Si nanosheets connected to the Si<111> nanowires, like sprouts or leaves with petioles, was observed, and the surface of the nanosheets was Si{111}. The nanosheets were grown in the growth direction of <211> perpendicular to that of the Si nanowires. It was evident from these structural features of the nanosheets that the nanosheets were formed by the twin-plane reentrant-edge mechanism. The feature of the observed lattice fringes, which do not appear for Si bulk crystals, of the Si(111) nanosheets obtained by high resolution transmission electron microscopy was clearly explained due to the extra diffraction spots that arose by the reciprocal lattice streaking effect.

  12. Dose evaluation for workers employed in an industry involving enamel paints containing zirconium silicate; Valutazione di dose per i lavoratori occupati in una industria che utilizza vernici a smalto contenenti silicato di zirconio

    Energy Technology Data Exchange (ETDEWEB)

    Castellani, C.M.; Berico, M.; De Zaiacomo, T.; Formignani, M.; Ianni, A.; Nobili, C.; Sandri, S.; Vasselli, R. [ENEA, Centro Ricerche Ezio Clementel, Bologna (Italy). Dipt. Ambiente

    1999-07-01

    In the frame of the European Recommendations for radiological protection, an evaluation of the annual dose has been made for workers employed in an industry for the production of sanitary equipment involving the use of enamel paints containing zirconium silicate. [Italian] Nella prospettiva dell'applicazione della direttiva europea relativa alla protezione radiologica dei lavoratori, vengono presentati i risultati relativi alla valutazione di dose annuale complessiva per i lavoratori occupati in una industria per la produzione di articoli igienico-sanitari che utilizza vernici a smalto contenenti silicato di zirconio. Il fine e' la valutazione del problema radioprotezionistico per gli addetti a causa delle impurezza radioattive presenti nei materiali utlizzati.

  13. Illustrations to “Gespräche in dem Reiche derer Todten zwischen dem vortreflichen Moscowitischen Czaar Petro Magno und dem grossen Tyrannen Ivan Basilowiz II” (Peter the Great and Ivan the Terrible) by David Fassmann (1725)

    OpenAIRE

    Ekaterina A. Skvortcova

    2017-01-01

    The journal created by David Fassmann (1683–1744), Gespräche in dem Reiche derer Todten, edited in Leipzig, was a huge success. Each of the 240 issues presents a dialogue between two historical figures from the afterworld. In the 83rd–86th Entrevuë, the interlocutors are Peter the Great and Ivan the Terrible. The texts of the four conversations were thoroughly examined by Eckhard Matthes (1987). The present paper explores how the illustrations to the 83rd–86th Entrevuë visualize the texts, w...

  14. Mechanics of patterned helical Si springs on Si substrate.

    Science.gov (United States)

    Liu, D L; Ye, D X; Khan, F; Tang, F; Lim, B K; Picu, R C; Wang, G C; Lu, T M

    2003-12-01

    The elastic response, including the spring constant, of individual Si helical-shape submicron springs, was measured using a tip-cantilever assembly attached to a conventional atomic force microscope. The isolated, four-turn Si springs were fabricated using oblique angle deposition with substrate rotation, also known as the glancing angle deposition, on a templated Si substrate. The response of the structures was modeled using finite elements, and it was shown that the conventional formulae for the spring constant required modifications before they could be used for the loading scheme used in the present experiment.

  15. Biomorphous SiSiC/Al-Si ceramic composites manufactured by squeeze casting: microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Zollfrank, C.; Travitzky, N.; Sieber, H.; Greil, P. [Department of Materials Science, Glass and Ceramics, University of Erlangen-Nuernberg (Germany); Selchert, T. [Advanced Ceramics Group, Technical University of Hamburg-Harburg (Germany)

    2005-08-01

    SiSiC/Al-Si composites were fabricated by pressure-assisted infiltration of an Al-Si alloy into porous biocarbon preforms derived from the rattan palm. Al-Si alloy was found in the pore channels of the biomorphous SiSiC preform, whereas SiC and carbon were present in the struts. The formation of a detrimental Al{sub 4}C{sub 3}-phase was not observed in the composites. A bending strength of 200 MPa was measured. The fractured surfaces showed pull-out of the Al-alloy. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  16. Fabrication and Mechanical Properties of SiCw(p/SiC-Si Composites by Liquid Si Infiltration using Pyrolysed Rice Husks and SiC Powders as Precursors

    Directory of Open Access Journals (Sweden)

    Dan Zhu

    2014-03-01

    Full Text Available Dense silicon carbide (SiC matrix composites with SiC whiskers and particles as reinforcement were prepared by infiltrating molten Si at 1550 °C into porous preforms composed of pyrolysed rice husks (RHs and extra added SiC powder in different ratios. The Vickers hardness of the composites showed an increase from 18.6 to 21.3 GPa when the amount of SiC added in the preforms was 20% (w/w, and then decreased to 17.3 GPa with the increase of SiC added in the preforms up to 80% (w/w. The values of flexural strength of the composites initially decreased when 20% (w/w SiC was added in the preform and then increased to 587 MPa when the SiC concentration reached 80% (w/w. The refinement of SiC particle sizes and the improvement of the microstructure in particle distribution of the composites due to the addition of external SiC played an effective role in improving the mechanical properties of the composites.

  17. Low-temperature magnetotransport in Si/SiGe heterostructures on 300 mm Si wafers

    Science.gov (United States)

    Scappucci, Giordano; Yeoh, L.; Sabbagh, D.; Sammak, A.; Boter, J.; Droulers, G.; Kalhor, N.; Brousse, D.; Veldhorst, M.; Vandersypen, L. M. K.; Thomas, N.; Roberts, J.; Pillarisetty, R.; Amin, P.; George, H. C.; Singh, K. J.; Clarke, J. S.

    Undoped Si/SiGe heterostructures are a promising material stack for the development of spin qubits in silicon. To deploy a qubit into high volume manufacturing in a quantum computer requires stringent control over substrate uniformity and quality. Electron mobility and valley splitting are two key electrical metrics of substrate quality relevant for qubits. Here we present low-temperature magnetotransport measurements of strained Si quantum wells with mobilities in excess of 100000 cm2/Vs fabricated on 300 mm wafers within the framework of advanced semiconductor manufacturing. These results are benchmarked against the results obtained in Si quantum wells deposited on 100 mm Si wafers in an academic research environment. To ensure rapid progress in quantum wells quality we have implemented fast feedback loops from materials growth, to heterostructure FET fabrication, and low temperature characterisation. On this topic we will present recent progress in developing a cryogenic platform for high-throughput magnetotransport measurements.

  18. Effect of hydrogen on passivation quality of SiNx/Si-rich SiNx stacked layers deposited by catalytic chemical vapor deposition on c-Si wafers

    International Nuclear Information System (INIS)

    Thi, Trinh Cham; Koyama, Koichi; Ohdaira, Keisuke; Matsumura, Hideki

    2015-01-01

    We investigate the role of hydrogen content and fixed charges of catalytic chemical vapor deposited (Cat-CVD) SiN x /Si-rich SiN x stacked layers on the quality of crystalline silicon (c-Si) surface passivation. Calculated density of fixed charges is on the order of 10 12 cm −2 , which is high enough for effective field effect passivation. Hydrogen content in the films is also found to contribute significantly to improvement in passivation quality of the stacked layers. Furthermore, Si-rich SiN x films deposited with H 2 dilution show better passivation quality of SiN x /Si-rich SiN x stacked layers than those prepared without H 2 dilution. Effective minority carrier lifetime (τ eff ) in c-Si passivated by SiN x /Si-rich SiN x stacked layers is as high as 5.1 ms when H 2 is added during Si-rich SiN x deposition, which is much higher than the case of using Si-rich SiN x films prepared without H 2 dilution showing τ eff of 3.3 ms. - Highlights: • Passivation mechanism of Si-rich SiN x /SiN x stacked layers is investigated. • H atoms play important role in passivation quality of the stacked layer. • Addition of H 2 gas during Si-rich SiN x film deposition greatly enhances effective minority carrier lifetime (τ eff ). • For a Si-rich SiN x film with refractive index of 2.92, τ eff improves from 3.3 to 5.1 ms by H 2 addition

  19. Low dose irradiation performance of SiC interphase SiC/SiC composites

    International Nuclear Information System (INIS)

    Snead, L.L.; Lowden, R.A.; Strizak, J.; More, K.L.; Eatherly, W.S.; Bailey, J.; Williams, A.M.; Osborne, M.C.; Shinavski, R.J.

    1998-01-01

    Reduced oxygen Hi-Nicalon fiber reinforced composite SiC materials were densified with a chemically vapor infiltrated (CVI) silicon carbide (SiC) matrix and interphases of either 'porous' SiC or multilayer SiC and irradiated to a neutron fluence of 1.1 x 10 25 n m -2 (E>0.1 MeV) in the temperature range of 260 to 1060 C. The unirradiated properties of these composites are superior to previously studied ceramic grade Nicalon fiber reinforced/carbon interphase materials. Negligible reduction in the macroscopic matrix microcracking stress was observed after irradiation for the multilayer SiC interphase material and a slight reduction in matrix microcracking stress was observed for the composite with porous SiC interphase. The reduction in strength for the porous SiC interfacial material is greatest for the highest irradiation temperature. The ultimate fracture stress (in four point bending) following irradiation for the multilayer SiC and porous SiC interphase materials was reduced by 15% and 30%, respectively, which is an improvement over the 40% reduction suffered by irradiated ceramic grade Nicalon fiber materials fabricated in a similar fashion, though with a carbon interphase. The degradation of the mechanical properties of these composites is analyzed by comparison with the irradiation behavior of bare Hi-Nicalon fiber and Morton chemically vapor deposited (CVD) SiC. It is concluded that the degradation of these composites, as with the previous generation ceramic grade Nicalon fiber materials, is dominated by interfacial effects, though the overall degradation of fiber and hence composite is reduced for the newer low-oxygen fiber. (orig.)

  20. Nitric acid oxidation of Si (NAOS) method for low temperature fabrication of SiO{sub 2}/Si and SiO{sub 2}/SiC structures

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, H., E-mail: koba771@ybb.ne.jp [Institute of Scientific and Industrial Research, Osaka University, and CREST, Japan Science and Technology Agency, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Imamura, K.; Kim, W.-B.; Im, S.-S.; Asuha [Institute of Scientific and Industrial Research, Osaka University, and CREST, Japan Science and Technology Agency, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2010-07-15

    We have developed low temperature formation methods of SiO{sub 2}/Si and SiO{sub 2}/SiC structures by use of nitric acid, i.e., nitric acid oxidation of Si (or SiC) (NAOS) methods. By use of the azeotropic NAOS method (i.e., immersion in 68 wt% HNO{sub 3} aqueous solutions at 120 deg. C), an ultrathin (i.e., 1.3-1.4 nm) SiO{sub 2} layer with a low leakage current density can be formed on Si. The leakage current density can be further decreased by post-metallization anneal (PMA) at 200 deg. C in hydrogen atmosphere, and consequently the leakage current density at the gate bias voltage of 1 V becomes 1/4-1/20 of that of an ultrathin (i.e., 1.5 nm) thermal oxide layer usually formed at temperatures between 800 and 900 deg. C. The low leakage current density is attributable to (i) low interface state density, (ii) low SiO{sub 2} gap-state density, and (iii) high band discontinuity energy at the SiO{sub 2}/Si interface arising from the high atomic density of the NAOS SiO{sub 2} layer. For the formation of a relatively thick (i.e., {>=}10 nm) SiO{sub 2} layer, we have developed the two-step NAOS method in which the initial and subsequent oxidation is performed by immersion in {approx}40 wt% HNO{sub 3} and azeotropic HNO{sub 3} aqueous solutions, respectively. In this case, the SiO{sub 2} formation rate does not depend on the Si surface orientation. Using the two-step NAOS method, a uniform thickness SiO{sub 2} layer can be formed even on the rough surface of poly-crystalline Si thin films. The atomic density of the two-step NAOS SiO{sub 2} layer is slightly higher than that for thermal oxide. When PMA at 250 deg. C in hydrogen is performed on the two-step NAOS SiO{sub 2} layer, the current-voltage and capacitance-voltage characteristics become as good as those for thermal oxide formed at 900 deg. C. A relatively thick (i.e., {>=}10 nm) SiO{sub 2} layer can also be formed on SiC at 120 deg. C by use of the two-step NAOS method. With no treatment before the NAOS method

  1. Grafted SiC nanocrystals

    DEFF Research Database (Denmark)

    Saini, Isha; Sharma, Annu; Dhiman, Rajnish

    2017-01-01

    ), raman spectroscopy and X-ray diffraction (XRD) measurements. UV–Visible absorption spectroscopy was used to study optical properties such as optical energy gap (Eg), Urbach's energy (Eu), refractive index (n), real (ε1) and imaginary (ε2) parts of dielectric constant of PVA as well as PVA......Polyvinyl alcohol (PVA) grafted SiC (PVA-g-SiC)/PVA nanocomposite was synthesized by incorporating PVA grafted silicon carbide (SiC) nanocrystals inside PVA matrix. In-depth structural characterization of resulting nanocomposite was carried out using fourier transform infrared spectroscopy (FTIR...

  2. Radiation emission from wrinkled SiGe/SiGe nanostructure

    Czech Academy of Sciences Publication Activity Database

    Fedorchenko, Alexander I.; Cheng, H. H.; Sun, G.; Soref, R. A.

    2010-01-01

    Roč. 96, č. 11 (2010), s. 113104-113107 ISSN 0003-6951 Institutional research plan: CEZ:AV0Z20760514 Keywords : SiGe wrinkled nanostructures * si-based optical emitter * synchrotron radiation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.820, year: 2010 http://apl.aip.org/resource/1/applab/v96/i11/p113104_s1?isAuthorized=no

  3. Electrical properties of Si/Si1-xGex/Si inverted modulation doped structures

    International Nuclear Information System (INIS)

    Sadeghzadeh, M.A.

    1998-12-01

    This thesis is a report of experimental investigations of growth strategy and electrical properties of Si/Si 1-x Ge x /Si inverted Modulation Doped (MD) structures grown by solid source Molecular Beam Epitaxy (MBE). If the grown Si layer is B-doped at some distance (as spacer) before or after the alloy layer, this remote doping induces the formation of a quasi Two Dimensional Hole Gas (2-DHG) near to the inverted (SiGe on Si) or normal (Si on SiGe) heterointerfaces of the Si/Si 1-x Ge x /Si quantum well, respectively. The latter arrangement is the well known 'normal' MD structure but the former one is the so-called 'inverted' MD structure which is of great interest for Field Effect Transistor (FET) applications. A reproducible growth strategy was employed by the use of a thick (400nm) Si cap for inverted MD structures with Ge composition in the range of 16-23%. Boron segregation and cap surface charges are significant in these inverted structures with small ( 20nm) spacer layers, respectively. It was demonstrated by secondary ion mass spectroscopy (SIMS) that boron segregation, which causes a reduction in the effective spacer dimension, can be suppressed by growth interruption after boron doping. The enhancement in hole sheet density with increasing Si cap layer thickness, is attributed to a reduction in the influence of positive surface charges in these structures. Top-gated devices were fabricated using these structures and the hole sheet density could be varied by applying a voltage to the metal-semiconductor gate, and the maximum Hall mobility of 5550 cm 2 V -1 s -1 with 4.2x10 11 cm -2 was measured (at 1.6K) in these structures. Comparison of measured Hall mobility (at 4.2K) as a function of hole sheet density in normal and inverted MD structures implies that both 2-DHG confined at normal and/or inverted structures are subjected to very similar interface charge, roughness, and alloy scattering potentials. Low temperatures magnetotransport measurements (down to

  4. High-Temperature, Perhaps Silicic, Volcanism on Mars Evidenced by Tridymite Detection in High-SiO2 Sedimentary Rock at Gale Crater, Mars

    Science.gov (United States)

    Morris, R. V.; Vaniman, D. T.; Blake, D. F.; Gellert, R.; Chipera, S. J.; Rampe, E. B.; Ming, D. W.; Morrison, S. M.; Downs, R. T.; Treiman, A. H.; hide

    2016-01-01

    The Mars Science Laboratory (MSL) rover, Curiosity, has been exploring sedimentary rocks within Gale crater since landing in August, 2012. On the lower slopes of Aeolis Mons (a.k.a. Mount Sharp), drill powder was collected from a high-silica (74 wt% SiO2) outcrop named Buckskin (BK). It was a surprise to find that the Buckskin sample contained significant amounts of the relatively rare silica polymorph tridymite. We describe the setting of the Buckskin sample, the detection of tridymite by the MSL Chemistry and Mineralogy (CheMin) X-ray diffraction instrument, and detection implications. Geologic setting: The Buckskin outcrop is part of the Murray formation exposed in the Marias Pass area. The formation was previously studied by CheMin in the Pahrump Hills member [1] where three samples of drill fines were analyzed (Confidence Hills (CH), Mojave2 (MJ) and Telegraph Peak (TP) [2]). Assuming approximately horizontal bedding, the Buckskin outcrop is approx.15 m stratigraphically above the bottom of the Pahrump Hills member. Mudstone, generally characterized by fine lamination, is the dominant depositional facies [1]. Buckskin Mineralogical and Chemical Composition: The CheMin instrument and XRD pattern analysis procedures have been previously discussed [3-6]. The diffraction pattern used for quantitative XRD analysis (Fig. 1) is the sum of the first 4 of 45 diffraction images. The remaining images are all characterized by both on-ring and off-ring diffraction spots that we attributed to poor grain motion and particle clumping. Coincident with particle clumping was a significant decrease in the intensity of the tridymite diffraction peaks (Fig. 2a). The derived mineralogical composition of the crystalline component (derived from the first 4 diffraction images) is given in Table 1. The tridymite is well-crystalline and its pattern is refined as monoclinic tridymite (Fig 1). Mineral chemical compositions were derived from XRD unit cell parameters or obtained from

  5. ‘Unkind and cruel, to deceive your Son | In borrow’d Shapes, and his Embrace to shun’: Mother-son love in T. S. Eliot’s ‘La Figlia Che Piange’

    Directory of Open Access Journals (Sweden)

    Matthew Geary

    2015-01-01

    Full Text Available T. S. Eliot's "La Figlia Che Piange" (1916 is a curious anomaly in his early works. It stands out as a love poem of outstanding grace portraying a more positive relationship to the feminine compared to other poems contemporaneous with its writing such as "The Love Song of St. Sebastian" (1914 and "Hysteria" (1915. This essay shows the import of Eliot's chosen epigraph for "La Figlia" taken from Virgil's Aeneid to have been largely neglected or misread by critics. As a consequence, it argues that critical readings have crucially missed the presence of a shrouded maternal aspect within the poem. Through the lens of Lacanian psychoanalysis and the work of adherents to Lacanian theory — such as Bruce Fink, Shoshana Felman and Slavoj Zizek — this paper newly argues that the poem's meditation on the issues of union and separation between two lovers is in fact a screen for deeper unconscious ambivalent feelings between mother and son. That is to say, Eliot's "La Figlia Che Piange" shows a failed attempt to reconstruct, traverse and separate from the "fundamental fantasy" unconsciously orientating the male speaker of the poem and his desire.

  6. Total Ionizing Dose Effects of Si Vertical Diffused MOSFET with SiO2 and Si3N4/SiO2 Gate Dielectrics

    Directory of Open Access Journals (Sweden)

    Jiongjiong Mo

    2017-01-01

    Full Text Available The total ionizing dose irradiation effects are investigated in Si vertical diffused MOSFETs (VDMOSs with different gate dielectrics including single SiO2 layer and double Si3N4/SiO2 layer. Radiation-induced holes trapping is greater for single SiO2 layer than for double Si3N4/SiO2 layer. Dielectric oxidation temperature dependent TID effects are also studied. Holes trapping induced negative threshold voltage shift is smaller for SiO2 at lower oxidation temperature. Gate bias during irradiation leads to different VTH shift for different gate dielectrics. Single SiO2 layer shows the worst negative VTH at VG=0 V, while double Si3N4/SiO2 shows negative VTH shift at VG=-5 V, positive VTH shift at VG=10 V, and negligible VTH shift at VG=0 V.

  7. On the line intensity ratios of prominent Si II, Si III, and Si IV multiplets

    International Nuclear Information System (INIS)

    Djenize, S.; Sreckovic, A.; Bukvic, S.

    2010-01-01

    Line intensities of singly, doubly and triply ionized silicon (Si II, Si III, and Si IV, respectively) belonging to the prominent higher multiplets, are of interest in laboratory and astrophysical plasma diagnostics. We measured these line intensities in the emission spectra of pulsed helium discharge. The Si II line intensity ratios in the 3s3p 22 D-3s 2 4p 2 P o , 3s 2 3d 2 D-3s 2 4f 2 F o , and 3s 2 4p 2 P o -3s 2 4d 2 D transitions, the Si III line intensity ratios in the 3s3d 3 D-3s4p 3 P o , 3s4p 3 P o -3s4d 3 D, 3s4p 3 P o -3s5s 3 S, 3s4s 3 S-3s4p 3 P o , and 3s4f 3 F o -3s5g 3 G transitions, and the Si IV line intensity ratios in the 4p 2 P o -4d 2 D and 4p 2 P o -5s 2 S transitions were obtained in a helium plasma at an electron temperature of about 17,000 ± 2000 K. Line shapes were recorded using a spectrograph and an ICCD camera as a highly-sensitive detection system. The silicon atoms were evaporated from a Pyrex discharge tube designed for the purpose. They represent impurities in the optically thin helium plasma at the silicon ionic wavelengths investigated. The line intensity ratios obtained were compared with those available in the literature, and with values calculated on the basis of available transition probabilities. The experimental data corresponded well with line intensity ratios calculated using the transition probabilities obtained from a Multi Configuration Hartree-Fock approximation for Si III and Si IV spectra. We recommend corrections of some Si II transition probabilities.

  8. SiC Nanoparticles Toughened-SiC/MoSi2-SiC Multilayer Functionally Graded Oxidation Protective Coating for Carbon Materials at High Temperatures

    Science.gov (United States)

    Abdollahi, Alireza; Ehsani, Naser; Valefi, Zia; Khalifesoltani, Ali

    2017-05-01

    A SiC nanoparticle toughened-SiC/MoSi2-SiC functionally graded oxidation protective coating on graphite was prepared by reactive melt infiltration (RMI) at 1773 and 1873 K under argon atmosphere. The phase composition and anti-oxidation behavior of the coatings were investigated. The results show that the coating was composed of MoSi2, α-SiC and β-SiC. By the variations of Gibbs free energy (calculated by HSC Chemistry 6.0 software), it could be suggested that the SiC coating formed at low temperatures by solution-reprecipitation mechanism and at high temperatures by gas-phase reactions and solution-reprecipitation mechanisms simultaneously. SiC nanoparticles could improve the oxidation resistance of SiC/MoSi2-SiC multiphase coating. Addition of SiC nanoparticles increases toughness of the coating and prevents spreading of the oxygen diffusion channels in the coating during the oxidation test. The mass loss and oxidation rate of the SiC nanoparticle toughened-SiC/MoSi2-SiC-coated sample after 10-h oxidation at 1773 K were only 1.76% and 0.32 × 10-2 g/cm3/h, respectively.

  9. Growth of CNTs on Fe-Si catalyst prepared on Si and Al coated Si substrates

    International Nuclear Information System (INIS)

    Teng, F-Y; Ting, J-M; Sharma, Sahendra P; Liao, Kun-Hou

    2008-01-01

    In this paper we report the effect of Al interlayers on the growth characteristics of carbon nanotubes (CNTs) using as-deposited and plasma etched Fe-Si catalyst films as the catalysts. Al interlayers having various thicknesses ranging from 2 to 42 nm were deposited on Si substrates prior to the deposition of Fe-Si catalysts. It was found that the Al interlayer diffuses into the Fe-Si catalyst during the plasma etching prior to the CNT growth, leading to the swelling and amorphization of the catalyst. This allows enhanced carbon diffusion in the catalyst and therefore a faster growth rate of the resulting CNTs. It was also found that use of an Al interlayer having a thickness of ∼3 ± 1 nm is most effective. Due to the effectiveness of this, the normally required catalyst etching is no longer needed for the growth of CNTs

  10. Growth of CNTs on Fe-Si catalyst prepared on Si and Al coated Si substrates.

    Science.gov (United States)

    Teng, F-Y; Ting, Jyh-Ming; Sharma, Sahendra P; Liao, Kun-Hou

    2008-03-05

    In this paper we report the effect of Al interlayers on the growth characteristics of carbon nanotubes (CNTs) using as-deposited and plasma etched Fe-Si catalyst films as the catalysts. Al interlayers having various thicknesses ranging from 2 to 42 nm were deposited on Si substrates prior to the deposition of Fe-Si catalysts. It was found that the Al interlayer diffuses into the Fe-Si catalyst during the plasma etching prior to the CNT growth, leading to the swelling and amorphization of the catalyst. This allows enhanced carbon diffusion in the catalyst and therefore a faster growth rate of the resulting CNTs. It was also found that use of an Al interlayer having a thickness of ∼3 ± 1 nm is most effective. Due to the effectiveness of this, the normally required catalyst etching is no longer needed for the growth of CNTs.

  11. SI units in engineering and technology

    CERN Document Server

    Qasim, S H

    2016-01-01

    SI Units in Engineering and Technology focuses on the use of the International System of Units-Systeme International d'Unités (SI). The publication first elaborates on the SI, derivation of important engineering units, and derived SI units in science and engineering. Discussions focus on applied mechanics in mechanical engineering, electrical and magnetic units, stress and pressure, work and energy, power and force, and magnitude of SI units. The text then examines SI units conversion tables and engineering data in SI units. Tables include details on the sectional properties of metals in SI units, physical properties of important molded plastics, important physical constants expressed in SI units, and temperature, area, volume, and mass conversion. Tables that show the mathematical constants, standard values expressed in SI units, and Tex count conversion are also presented. The publication is a dependable source of data for researchers interested in the use of the International System of Units-Systeme Inter...

  12. Modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy

    International Nuclear Information System (INIS)

    Wu Yuying; Liu Xiangfa; Jiang Binggang; Huang Chuanzhen

    2009-01-01

    Modification effect of Ni-38 wt.%Si on the Al-12 wt.%Si alloy has been studied by differential scanning calorimeter, torsional oscillation viscometer and liquid X-ray diffraction experiments. It is found that there is a modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy, i.e. primary Si can precipitate in the microstructure of Al-12 wt.%Si alloy when Ni and Si added in the form of Ni-38 wt.%Si, but not separately. Ni-38 wt.%Si alloy brings 'genetic materials' into the Al-Si melt, which makes the melt to form more ordering structure, promotes the primary Si precipitated. Moreover, the addition of Ni-38 wt.%Si, which decreases the solidification supercooling degree of Al-12 wt.%Si alloy, is identical to the effect of heterogeneous nuclei.

  13. Modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yuying [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China)], E-mail: wyy532001@163.com; Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China); Shandong Binzhou Bohai Piston Co., Ltd., Binzhou 256602, Shandong (China); Jiang Binggang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China); Huang Chuanzhen [School of Mechanical Engineering, Shandong University, Jinan 250061 (China)

    2009-05-27

    Modification effect of Ni-38 wt.%Si on the Al-12 wt.%Si alloy has been studied by differential scanning calorimeter, torsional oscillation viscometer and liquid X-ray diffraction experiments. It is found that there is a modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy, i.e. primary Si can precipitate in the microstructure of Al-12 wt.%Si alloy when Ni and Si added in the form of Ni-38 wt.%Si, but not separately. Ni-38 wt.%Si alloy brings 'genetic materials' into the Al-Si melt, which makes the melt to form more ordering structure, promotes the primary Si precipitated. Moreover, the addition of Ni-38 wt.%Si, which decreases the solidification supercooling degree of Al-12 wt.%Si alloy, is identical to the effect of heterogeneous nuclei.

  14. Construction and characterization of spherical Si solar cells combined with SiC electric power inverter

    Science.gov (United States)

    Oku, Takeo; Matsumoto, Taisuke; Hiramatsu, Kouichi; Yasuda, Masashi; Shimono, Akio; Takeda, Yoshikazu; Murozono, Mikio

    2015-02-01

    Spherical silicon (Si) photovoltaic solar cell systems combined with an electric power inverter using silicon carbide (SiC) field-effect transistor (FET) were constructed and characterized, which were compared with an ordinary Si-based converter. The SiC-FET devices were introduced in the direct current-alternating current (DC-AC) converter, which was connected with the solar panels. The spherical Si solar cells were used as the power sources, and the spherical Si panels are lighter and more flexible compared with the ordinary flat Si solar panels. Conversion efficiencies of the spherical Si solar cells were improved by using the SiC-FET.

  15. Electrochemical characteristics of nc-Si/SiC composite for anode electrode of lithium ion batteries

    International Nuclear Information System (INIS)

    Jeon, Bup Ju; Lee, Joong Kee

    2014-01-01

    Graphical abstract: Cycling performances and coulombic efficiencies of the nc-Si/SiC composite anodes at different CH 4 /SiH 4 mole ratios. -- Highlights: • Our work has focused on irreversible discharge capacity and capacity retention of nc-Si/SiC composite particles. • Particles comprised a mixed construction of nc-Si/SiC structure with dual phases. • The SiC phase acted as retarding media, leading to enhanced cycle stability. -- Abstract: nc-Si/SiC composite particles were prepared as an anode material for lithium ion batteries using a plasma jet with DC arc discharge. The composition of the nc-Si/SiC composite particles was controlled by setting the mole ratio of CH 4 and SiH 4 precursor gases. X-ray diffraction, TEM images, and Raman shift analyses revealed that the synthesized nc-Si/SiC composite particles comprised a construction of nano-nocaled structure with crystalline phases of active silicon, highly disordered amorphous carbon of graphite and crystalline phases of β-SiC. In the experimental range examined, the nc-Si/SiC composite particles showed good coulombic efficiency in comparison with particles high Si–Si bonding content due to the interplay of particles with a small proportion of carbon and the buffering effect against volume expansion by structural stabilization, and played a role as retarding media for the rapid electrochemical reactions of the SiC crystal against lithium

  16. Electrochemical characteristics of nc-Si/SiC composite for anode electrode of lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Bup Ju [Department of Energy Resources, Shinhan University, 233-1, Sangpae-dong, Dongducheon, Gyeonggi-do, 483-777 (Korea, Republic of); Lee, Joong Kee, E-mail: leejk@kist.re.kr [Advanced Energy Materials Processing Laboratory, Center for Energy Convergence Research, Green City Technology Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)

    2014-03-25

    Graphical abstract: Cycling performances and coulombic efficiencies of the nc-Si/SiC composite anodes at different CH{sub 4}/SiH{sub 4} mole ratios. -- Highlights: • Our work has focused on irreversible discharge capacity and capacity retention of nc-Si/SiC composite particles. • Particles comprised a mixed construction of nc-Si/SiC structure with dual phases. • The SiC phase acted as retarding media, leading to enhanced cycle stability. -- Abstract: nc-Si/SiC composite particles were prepared as an anode material for lithium ion batteries using a plasma jet with DC arc discharge. The composition of the nc-Si/SiC composite particles was controlled by setting the mole ratio of CH{sub 4} and SiH{sub 4} precursor gases. X-ray diffraction, TEM images, and Raman shift analyses revealed that the synthesized nc-Si/SiC composite particles comprised a construction of nano-nocaled structure with crystalline phases of active silicon, highly disordered amorphous carbon of graphite and crystalline phases of β-SiC. In the experimental range examined, the nc-Si/SiC composite particles showed good coulombic efficiency in comparison with particles high Si–Si bonding content due to the interplay of particles with a small proportion of carbon and the buffering effect against volume expansion by structural stabilization, and played a role as retarding media for the rapid electrochemical reactions of the SiC crystal against lithium.

  17. Circumferential tensile test method for mechanical property evaluation of SiC/SiC tube

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Ju-Hyeon, E-mail: 15096018@mmm.muroran-it.ac.jp [Graduate School, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Kishimoto, Hirotatsu [Graduate School, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); OASIS, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Park, Joon-soo [OASIS, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Nakazato, Naofumi [Graduate School, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan); Kohyama, Akira [OASIS, Muroran Institute of Technology, 27-1, Muroran, Hokkaido (Japan)

    2016-11-01

    Highlights: • NITE SiC/SiC cooling channel system to be a candidate of divertor system in future. • Hoop strength is one of the important factors for a tube. • This research studies the relationship between deformation and strain of SiC/SiC tube. - Abstract: SiC fiber reinforced/SiC matrix (SiC/SiC) composite is expected to be a candidate material for the first-wall, components in the blanket and divertor of fusion reactors in future. In such components, SiC/SiC composites need to be formed to be various shapes. SiC/SiC tubes has been expected to be employed for blanket and divertor after DEMO reactor, but there is not established mechanical investigation technique. Recent progress of SiC/SiC processing techniques is likely to realize strong, having gas tightness SiC/SiC tubes which will contribute for the development of fusion reactors. This research studies the relationship between deformation and strain of SiC/SiC tube using a circumferential tensile test method to establish a mechanical property investigation method of SiC/SiC tubes.

  18. Si, Ge and SiGe wires for sensor application

    International Nuclear Information System (INIS)

    Druzhinin, A.A.; Khoverko, Yu.M.; Ostrovskii, I.P.; Nichkalo, S.I.; Nikolaeva, A.A.; Konopko, L.A.; Stich, I.

    2011-01-01

    Resistance and magnetoresistance of Si, Ge and Si-Ge micro- and nanowires were studied in temperature range 4,2-300 K at magnetic fields up to 14 T. The wires diameters range from 200 nm to 20 μm. Ga-In gates were created to wires and ohmic I-U characteristics were observed in all temperature range. It was found high elastic strain for Ge nanowires (of about 0,7%) as well as high magnitude of magnetoresistance (of about 250% at 14 T), which was used to design multifunctional sensor of simultaneous measurements of strain and magnetic field intensity. (authors)

  19. Doping effect in Si nanocrystals

    Science.gov (United States)

    Li, Dongke; Xu, Jun; Zhang, Pei; Jiang, Yicheng; Chen, Kunji

    2018-06-01

    Intentional doping in semiconductors is a fundamental issue since it can control the conduction type and ability as well as modify the optical and electronic properties. To realize effective doping is the basis for developing semiconductor devices. However, by reducing the size of a semiconductor, like Si, to the nanometer scale, the doping effects become complicated due to the coupling between the quantum confinement effect and the surfaces and/or interfaces effect. In particular, by introducing phosphorus or boron impurities as dopants into material containing Si nanocrystals with a dot size of less than 10 nm, it exhibits different behaviors and influences on the physical properties from its bulk counterpart. Understanding the doping effects in Si nanocrystals is currently a challenge in order to further improve the performance of the next generation of nano-electronic and photonic devices. In this review, we present an overview of the latest theoretical studies and experimental results on dopant distributions and their effects on the electronic and optical properties of Si nanocrystals. In particular, the advanced characterization techniques on dopant distribution, the carrier transport process as well as the linear and nonlinear optical properties of doped Si nanocrystals, are systematically summarized.

  20. Financial balance of the recovery of energy starting from the thermal-destruction; Bilancio economico del recupero di energia dalla termodistruzione

    Energy Technology Data Exchange (ETDEWEB)

    Macchi, E. [Milan Politecnico, Milan (Italy). Dipt. Energetica

    2000-08-01

    elettrica installata, alla produzione elettrica lorda e al contributo fornito dagli RSU al teleriscaldamento. Si indicano quindi le principali grandezze che intervengono nelle valutazioni economiche (costi di investimento, vita utile dell'impianto, indici economici, tempi di realizzazione, costi operativi, rendimenti, affidabilita' e disponibilita' dell'impianto, valorizzazione dell'energia elettrica e termica generata, ricavi da smaltimento rifiuti), evidenziando l'importanza della taglia dell'impianto, che e' il vero fattore decisivo. Vengono prodotti esempi esplicativi del peso dei diversi fattori. In particolare, viene approfondito il ruolo dell'energia prodotta da RSU nel nuovo mercato elettrico liberalizzato, evidenziandone i vantaggi rispetto all'energia da fonti convenzionali. Si discutono infine le potenzialita' di impianti <>, che coniugano l'incenerimento degli RSU alla tecnologia dei cicli combinati alimentati da gas naturale.

  1. Reaction mechanisms at 4H-SiC/SiO2 interface during wet SiC oxidation

    Science.gov (United States)

    Akiyama, Toru; Hori, Shinsuke; Nakamura, Kohji; Ito, Tomonori; Kageshima, Hiroyuki; Uematsu, Masashi; Shiraishi, Kenji

    2018-04-01

    The reaction processes at the interface between SiC with 4H structure (4H-SiC) and SiO2 during wet oxidation are investigated by electronic structure calculations within the density functional theory. Our calculations for 4H-SiC/SiO2 interfaces with various orientations demonstrate characteristic features of the reaction depending on the crystal orientation of SiC: On the Si-face, the H2O molecule is stable in SiO2 and hardly reacts with the SiC substrate, while the O atom of H2O can form Si-O bonds at the C-face interface. Two OH groups are found to be at least necessary for forming new Si-O bonds at the Si-face interface, indicating that the oxidation rate on the Si-face is very low compared with that on the C-face. On the other hand, both the H2O molecule and the OH group are incorporated into the C-face interface, and the energy barrier for OH is similar to that for H2O. By comparing the calculated energy barriers for these reactants with the activation energies of oxide growth rate, we suggest the orientation-dependent rate-limiting processes during wet SiC oxidation.

  2. Analyses of the As doping of SiO{sub 2}/Si/SiO{sub 2} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ruffino, Francesco; Miritello, Maria [CNR-IMM MATIS, via S. Sofia 64, 95123 Catania (Italy); Tomasello, Mario Vincenzo [Scuola Superiore di Catania, via San Nullo 5/i, 95123 Catania (Italy); De Bastiani, Riccardo; Grimaldi, Maria Grazia [Dipartimento di Fisica ed Astronomia, Universita di Catania, via S. Sofia 64, 95123 Catania (Italy); CNR-IMM MATIS, via S. Sofia 64, 95123 Catania (Italy); Nicotra, Giuseppe; Spinella, Corrado [Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi (CNR-IMM), VIII Strada 5, 95121 Catania (Italy)

    2011-03-15

    We illustrate the behaviour of As when it is confined, by the implantation technique, in a SiO{sub 2}(70nm)/Si(30nm)/SiO{sub 2}(70nm) multilayer and its spatial redistribution when annealing processes are performed. By Rutherford backscattering spectrometry and Z-contrast transmission electron microscopy we found an As accumulation at the Si/SiO{sub 2} interfaces and at the Si grain boundaries with no segregation of the As in the Si layer. Such an effect is in agreement with a model that assumes a traps distribution in the Si in the first 2-3 nm above the SiO{sub 2}/Si interfaces and along the Si grain boundaries. The traps concentration at the Si/SiO{sub 2} interfaces was estimated in 10{sup 14} traps/cm{sup 2}. The outlined results can open perspectives on the doping properties of As in Si nanocrystals, whose applications in nanoelectronics and optoelectronics are widely investigated (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. High-dose MeV electron irradiation of Si-SiO2 structures implanted with high doses Si+

    Science.gov (United States)

    Kaschieva, S.; Angelov, Ch; Dmitriev, S. N.

    2018-03-01

    The influence was studied of 22-MeV electron irradiation on Si-SiO2 structures implanted with high-fluence Si+ ions. Our earlier works demonstrated that Si redistribution is observed in Si+-ion-implanted Si-SiO2 structures (after MeV electron irradiation) only in the case when ion implantation is carried out with a higher fluence (1016 cm-2). We focused our attention on the interaction of high-dose MeV electron irradiation (6.0×1016 cm-2) with n-Si-SiO2 structures implanted with Si+ ions (fluence 5.4×1016 cm-2 of the same order magnitude). The redistribution of both oxygen and silicon atoms in the implanted Si-SiO2 samples after MeV electron irradiation was studied by Rutherford back-scattering (RBS) spectroscopy in combination with a channeling technique (RBS/C). Our results demonstrated that the redistribution of oxygen and silicon atoms in the implanted samples reaches saturation after these high doses of MeV electron irradiation. The transformation of amorphous SiO2 surface into crystalline Si nanostructures (after MeV electron irradiation) was evidenced by atomic force microscopy (AFM). Silicon nanocrystals are formed on the SiO2 surface after MeV electron irradiation. The shape and number of the Si nanocrystals on the SiO2 surface depend on the MeV electron irradiation, while their size increases with the dose. The mean Si nanocrystals height is 16-20 nm after irradiation with MeV electrons at the dose of 6.0×1016 cm-2.

  4. Thermal shock properties of 2D-SiCf/SiC composites

    International Nuclear Information System (INIS)

    Lee, Sang Pill; Lee, Jin Kyung; Son, In Soo; Bae, Dong Su; Kohyama, Akira

    2012-01-01

    This paper dealt with the thermal shock properties of SiC f /SiC composites reinforced with two dimensional SiC fabrics. SiC f /SiC composites were fabricated by a liquid phase sintering process, using a commercial nano-size SiC powder and oxide additive materials. An Al 2 O 3 –Y 2 O 3 –SiO 2 powder mixture was used as a sintering additive for the consolidation of SiC matrix region. In this composite system, Tyranno SA SiC fabrics were also utilized as a reinforcing material. The thermal shock test for SiC f /SiC composites was carried out at the elevated temperature. Both mechanical strength and microstructure of SiC f /SiC composites were investigated by means of optical microscopy, SEM and three point bending test. SiC f /SiC composites represented a dense morphology with a porosity of about 8.2% and a flexural strength of about 160 MPs. The characterization of SiC f /SiC composites was greatly affected by the history of cyclic thermal shock. Especially, SiC f /SiC composites represented a reduction of flexural strength at the thermal shock temperature difference higher than 800 °C.

  5. High thermal conductivity SiC/SiC composites for fusion applications -- 2

    International Nuclear Information System (INIS)

    Kowbel, W.; Tsou, K.T.; Withers, J.C.; Youngblood, G.E.

    1998-01-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion Structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23--24, 1997. An unirradiated SiC/SiC composite made with MER-developed CVR SiC fiber and a hybrid PIP/CVI SiC matrix exhibited room temperature transverse thermal conductivity of 45 W/mK. An unirradiated SiC/SiC composite made from C/C composite totally CVR-converted to a SiC/SiC composite exhibited transverse thermal conductivity values of 75 and 35 W/mK at 25 and 1000 C, respectively. Both types of SiC/SiC composites exhibited non-brittle failure in flexure testing

  6. 32Si dating of sediments

    International Nuclear Information System (INIS)

    Morgenstern, U.

    2004-01-01

    Brief explanation of the use of 32 Si in the dating of sediments. 32 Si , with a half-life of c.140 years, can be applied in the age range 30-1000 years. An appropriate dating tool for that time range is essential because it includes three very important epochs: the impact of human colonisation and industrialisation during the last 150 years, the Little Ice Age between about 1650 AD and 1850 AD, and the last part of the Medieval Climatic Optimum. 23 refs

  7. SI units in radiation protection

    International Nuclear Information System (INIS)

    Herrmann, D.

    1976-10-01

    In the field of radiation protection all hitherto used units for activity, activity concentrations, exposure, absorbed dose, and dose rates have to be replaced by SI units during the next years. For this purpose graphs and conversion tables are given as well as recommendations on unit combinations preferentially to be used. As to the dose equivalent, it is suggested to introduce a new special unit being 100 times greater than the rem, instead of maintaining the rem or using the gray for both absorbed dose and dose equivalent. Measures and time schedule relating to the gradual transition to SI units in measuring techniques, training, and publishing et cetera are explained. (author)

  8. Cavities at the Si projected range by high dose and energy Si ion implantation in Si

    International Nuclear Information System (INIS)

    Canino, M.; Regula, G.; Lancin, M.; Xu, M.; Pichaud, B.; Ntzoenzok, E.; Barthe, M.F.

    2009-01-01

    Two series of n-type Si samples α and β are implanted with Si ions at high dose (1 x 10 16 ) and high energies, 0.3 and 1.0 MeV, respectively. Both sort of samples are then implanted with 5 x 10 16 He cm -2 (at 10 or 50 keV) and eventually with B atoms. Some of the samples are annealed at temperatures ranging from 800 to 1000 deg. C to allow the thermal growth of He-cavities, located between sample surface and the projected range (R p ) of Si. After the triple ion implantation, which corresponds to defect engineering, samples were characterized by cross-section transmission electron microscopy (XTEM). Voids (or bubbles) are observed not only at the R p (He) on all annealed samples, but also at the R p (Si) on β samples implanted with He at 50 keV. The samples are also studied by positron annihilation spectroscopy (PAS) and the spectra confirm that as-implanted samples contain di-vacancies and that the annealed ones, even at high temperature have bigger open volumes, which are assumed to be the same voids observed by XTEM. It is demonstrated that a sole Si implantation at high energy and dose is efficient to create cavities which are thermally stable up to 1000 deg. C only in the presence of He.

  9. Analysis of Si/SiGe Heterostructure Solar Cell

    Directory of Open Access Journals (Sweden)

    Ashish Kumar Singh

    2014-01-01

    Full Text Available Sunlight is the largest source of carbon-neutral energy. Large amount of energy, about 4.3 × 1020 J/hr (Lewis, 2005, is radiated because of nuclear fusion reaction by sun, but it is unfortunate that it is not exploited to its maximum level. Various photovoltaic researches are ongoing to find low cost, and highly efficient solar cell to fulfil looming energy crisis around the globe. Thin film solar cell along with enhanced absorption property will be the best, so combination of SiGe alloy is considered. The paper presented here consists of a numerical model of Si/Si1-xGex heterostructure solar cell. The research has investigated characteristics such as short circuit current density (Jsc, generation rate (G, absorption coefficient (α, and open circuit voltage (Voc with optimal Ge concentration. The addition of Ge content to Si layer will affect the property of material and can be calculated with the use of Vegard’s law. Due to this, short circuit current density increases.

  10. Microscopic and macroscopic characterization of the charging effects in SiC/Si nanocrystals/SiC sandwiched structures

    International Nuclear Information System (INIS)

    Xu, Jie; Xu, Jun; Wang, Yuefei; Cao, Yunqing; Li, Wei; Yu, Linwei; Chen, Kunji

    2014-01-01

    Microscopic charge injection into the SiC/Si nanocrystals/SiC sandwiched structures through a biased conductive AFM tip is subsequently characterized by both electrostatic force microscopy and Kelvin probe force microscopy (KPFM). The charge injection and retention characteristics are found to be affected by not only the band offset at the Si nanocrystals/SiC interface but also the doping type of the Si substrate. On the other hand, capacitance–voltage (C–V) measurements investigate the macroscopic charging effect of the sandwiched structures with a thicker SiC capping layer, where the charges are injected from the Si substrates. The calculated macroscopic charging density is 3–4 times that of the microscopic one, and the possible reason is the underestimation of the microscopic charging density caused by the averaging effect and detection delay in the KPFM measurements. (paper)

  11. Pressureless sintering of dense Si3N4 and Si3N4/SiC composites with nitrate additives

    International Nuclear Information System (INIS)

    Kim, J.Y.; Iseki, Takayoshi; Yano, Toyohiko

    1996-01-01

    The effect of aluminum and yttrium nitrate additives on the densification of monolithic Si 3 N 4 and a Si 3 N 4 /SiC composite by pressureless sintering was compared with that of oxide additives. The surfaces of Si 3 N 4 particles milled with aluminum and yttrium nitrates, which were added as methanol solutions, were coated with a different layer containing Al and Y from that of Si 3 N 4 particles milled with oxide additives. Monolithic Si 3 N 4 could be sintered to 94% of theoretical density (TD) at 1,500 C with nitrate additives. The sintering temperature was about 100 C lower than the case with oxide additives. After pressureless sintering at 1,750 C for 2 h in N 2 , the bulk density of a Si 3 N 4 /20 wt% SiC composite reached 95% TD with nitrate additives

  12. Si-O-Si bond-angle distribution in vitreous silica from first-principles 29Si NMR analysis

    International Nuclear Information System (INIS)

    Mauri, Francesco; Pasquarello, Alfredo; Pfrommer, Bernd G.; Yoon, Young-Gui; Louie, Steven G.

    2000-01-01

    The correlation between 29 Si chemical shifts and Si-O-Si bond angles in SiO 2 is determined within density-functional theory for the full range of angles present in vitreous silica. This relation closely reproduces measured shifts of crystalline polymorphs. The knowledge of the correlation allows us to reliably extract from the experimental NMR spectrum the mean (151 degree sign ) and the standard deviation (11 degree sign ) of the Si-O-Si angular distribution of vitreous silica. In particular, we show that the Mozzi-Warren Si-O-Si angular distribution is not consistent with the NMR data. This analysis illustrates the potential of our approach for structural determinations of silicate glasses. (c) 2000 The American Physical Society

  13. SI units in biomedical dosimetry

    International Nuclear Information System (INIS)

    Liden, K.

    1975-01-01

    The International commission on radiation units and measurements (ICRU), during the period from 1953 to 1962 presented its definitions of the quantities absorbed dose, exposure, activity, and dose equivalent and the corresponding special units the rad, the roentgen, the curie, and the rem. At the same time an international practical system of units was developed, Le Systeme International d'Unites (SI). It was adopted by the 11th Conference Generale des Poids et Mesures (CGPM) in 1960 and is now officially introduced in almost all countries. The general implementation of the SI means difficulties for the future use of the special radiation units, because the numerical factors involved prevent their adoption as SI units. In view of this, and after having sampled the opinion in the radiological field, the ICRU prepared a Statement on Units in July, 1974 which was forwarded to the Comite International des Poids et Mesures (CIPM) and its Comite Consultatif des Unites (CCU) for consideration. As a result of this statement the CIPM has now proposed, that the 15rh CGPM adopt special names for two SI units, namely the becquerel, symbol Bq, for the unit of activity of radionuclides equal to the reciprocal second, s 1- , and the gray, symbol Gy, for the unit of absorbed dose equal to the joule per kilogram, J/kg. The 15th CGPM will consider this matter in May, 1975. (author)

  14. Palladium transport in SiC

    International Nuclear Information System (INIS)

    Olivier, E.J.; Neethling, J.H.

    2012-01-01

    Highlights: ► We investigate the reaction of Pd with SiC at typical HTGR operating temperatures. ► The high temperature mobility of palladium silicides within polycrystalline SiC was studied. ► Corrosion of SiC by Pd was seen in all cases. ► The preferential corrosion and penetration of Pd along grain boundaries in SiC was found. ► The penetration and transport of palladium silicides in SiC along grain boundaries was found. - Abstract: This paper reports on a transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study of Pd corroded SiC. The reaction of Pd with different types of SiC at typical HTGR operating temperatures was examined. In addition the high temperature mobility of palladium silicides within polycrystalline SiC was investigated. The results indicated corrosion of the SiC by Pd in all cases studied. The corrosion leads to the formation of palladium silicides within the SiC, with the predominant phase found being Pd 2 Si. Evidence for the preferential corrosion and penetration of Pd along grain boundaries in polycrystalline SiC was found. The penetration and transport, without significant corrosion, of palladium silicides into polycrystalline SiC along grain boundaries was also observed. Implications of the findings with reference to the use of Tri Isotropic particles in HTGRs will be discussed.

  15. Palladium transport in SiC

    Energy Technology Data Exchange (ETDEWEB)

    Olivier, E.J., E-mail: jolivier@nmmu.ac.za [Centre for High Resolution Transmission Electron Microscopy, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Neethling, J.H. [Centre for High Resolution Transmission Electron Microscopy, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer We investigate the reaction of Pd with SiC at typical HTGR operating temperatures. Black-Right-Pointing-Pointer The high temperature mobility of palladium silicides within polycrystalline SiC was studied. Black-Right-Pointing-Pointer Corrosion of SiC by Pd was seen in all cases. Black-Right-Pointing-Pointer The preferential corrosion and penetration of Pd along grain boundaries in SiC was found. Black-Right-Pointing-Pointer The penetration and transport of palladium silicides in SiC along grain boundaries was found. - Abstract: This paper reports on a transmission electron microscopy (TEM) and scanning electron microscopy (SEM) study of Pd corroded SiC. The reaction of Pd with different types of SiC at typical HTGR operating temperatures was examined. In addition the high temperature mobility of palladium silicides within polycrystalline SiC was investigated. The results indicated corrosion of the SiC by Pd in all cases studied. The corrosion leads to the formation of palladium silicides within the SiC, with the predominant phase found being Pd{sub 2}Si. Evidence for the preferential corrosion and penetration of Pd along grain boundaries in polycrystalline SiC was found. The penetration and transport, without significant corrosion, of palladium silicides into polycrystalline SiC along grain boundaries was also observed. Implications of the findings with reference to the use of Tri Isotropic particles in HTGRs will be discussed.

  16. Advanced Optoelectronic Devices based on Si Quantum Dots/Si Nanowires Hetero-structures

    International Nuclear Information System (INIS)

    Xu, J; Zhai, Y Y; Cao, Y Q; Chen, K J

    2017-01-01

    Si quantum dots are currently extensively studied since they can be used to develop many kinds of optoelectronic devices. In this report, we review the fabrication of Si quantum dots (Si QD) /Si nanowires (Si NWs) hetero-structures by deposition of Si QDs/SiO 2 or Si QDs/SiC multilayers on Si NWs arrays. The electroluminescence and photovoltaic devices based on the formed hetero-structures have been prepared and the improved performance is confirmed. It is also found that the surface recombination via the surface defects states on the Si NWs, especially the ones obtained by the long-time etching, may deteriorate the device properties though they exhibit the better anti-reflection characteristics. The possible surface passivation approaches are briefly discussed. (paper)

  17. On formation of silicon nanocrystals under annealing SiO2 layers implanted with Si ions

    International Nuclear Information System (INIS)

    Kachurin, G.A.; Yanovskaya, S.G.; Volodin, V.A.; Kesler, V.G.; Lejer, A.F.; Ruault, M.-O.

    2002-01-01

    Raman scattering, X-ray photoelectron spectroscopy, and photoluminescence have been used to study the formation of silicon nanocrystals in SiO 2 implanted with Si ions. Si clusters have been formed at once in the postimplanted layers, providing the excessive Si concentration more ∼ 3 at. %. Si segregation with Si-Si 4 bonds formation is enhanced as following annealing temperature increase, however, the Raman scattering by Si clusters diminishes. The effect is explained by a transformation of the chain-like Si clusters into compact phase nondimensional structures. Segregation of Si nanoprecipitates had ended about 1000 deg C, but the strong photoluminescence typical for Si nanocrystals manifested itself only after 1100 deg C [ru

  18. Nanocatalytic growth of Si nanowires from Ni silicate coated SiC nanoparticles on Si solar cell.

    Science.gov (United States)

    Parida, Bhaskar; Choi, Jaeho; Ji, Hyung Yong; Park, Seungil; Lim, Gyoungho; Kim, Keunjoo

    2013-09-01

    We investigated the nanocatalytic growth of Si nanowires on the microtextured surface of crystalline Si solar cell. 3C-SiC nanoparticles have been used as the base for formation of Ni silicate layer in a catalytic reaction with the Si melt under H2 atmosphere at an annealing temperature of 1100 degrees C. The 10-nm thick Ni film was deposited after the SiC nanoparticles were coated on the microtextured surface of the Si solar cell by electron-beam evaporation. SiC nanoparticles form a eutectic alloy surface of Ni silicate and provide the base for Si supersaturation as well as the Ni-Si alloy layer on Si substrate surface. This bottom reaction mode for the solid-liquid-solid growth mechanism using a SiC nanoparticle base provides more stable growth of nanowires than the top reaction mode growth mechanism in the absence of SiC nanoparticles. Thermally excited Ni nanoparticle forms the eutectic alloy and provides collectively excited electrons at the alloy surface, which reduces the activation energy of the nanocatalytic reaction for formation of nanowires.

  19. Research on a Micro-Nano Si/SiGe/Si Double Heterojunction Electro-Optic Modulation Structure

    Directory of Open Access Journals (Sweden)

    Song Feng

    2018-01-01

    Full Text Available The electro-optic modulator is a very important device in silicon photonics, which is responsible for the conversion of optical signals and electrical signals. For the electro-optic modulator, the carrier density of waveguide region is one of the key parameters. The traditional method of increasing carrier density is to increase the external modulation voltage, but this way will increase the modulation loss and also is not conducive to photonics integration. This paper presents a micro-nano Si/SiGe/Si double heterojunction electro-optic modulation structure. Based on the band theory of single heterojunction, the barrier heights are quantitatively calculated, and the carrier concentrations of heterojunction barrier are analyzed. The band and carrier injection characteristics of the double heterostructure structure are simulated, respectively, and the correctness of the theoretical analysis is demonstrated. The micro-nano Si/SiGe/Si double heterojunction electro-optic modulation is designed and tested, and comparison of testing results between the micro-nano Si/SiGe/Si double heterojunction micro-ring electro-optic modulation and the micro-nano Silicon-On-Insulator (SOI micro-ring electro-optic modulation, Free Spectrum Range, 3 dB Bandwidth, Q value, extinction ratio, and other parameters of the micro-nano Si/SiGe/Si double heterojunction micro-ring electro-optic modulation are better than others, and the modulation voltage and the modulation loss are lower.

  20. Effect of Ti and Si interlayer materials on the joining of SiC ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Yang Il; Park, Jung Hwan; Kim, Hyun Gil; Park, Dong Jun; Park, Jeong Yong; Kim, Weon Ju [LWR Fuel Technology Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-08-15

    SiC-based ceramic composites are currently being considered for use in fuel cladding tubes in light-water reactors. The joining of SiC ceramics in a hermetic seal is required for the development of ceramic-based fuel cladding tubes. In this study, SiC monoliths were diffusion bonded using a Ti foil interlayer and additional Si powder. In the joining process, a very low uniaxial pressure of ∼0.1 MPa was applied, so the process is applicable for joining thin-walled long tubes. The joining strength depended strongly on the type of SiC material. Reaction-bonded SiC (RB-SiC) showed a higher joining strength than sintered SiC because the diffusion reaction of Si was promoted in the former. The joining strength of sintered SiC was increased by the addition of Si at the Ti interlayer to play the role of the free Si in RB-SiC. The maximum joint strength obtained under torsional stress was ∼100 MPa. The joint interface consisted of TiSi{sub 2}, Ti{sub 3}SiC{sub 2}, and SiC phases formed by a diffusion reaction of Ti and Si.

  1. Entrance channel excitations in the 28Si + 28Si reaction

    International Nuclear Information System (INIS)

    Decowski, P.; Gierlik, E.; Box, P.F.; Kamermans, R.; Nieuwenhuizen, G.J. van; Meijer, R.J.; Griffioen, K.A.; Wilschut, H.W.; Giorni, A.; Morand, C.; Demeyer, A.; Guinet, D.

    1991-01-01

    Velocity spectra of heavy ions produced in the 28 Si + 28 Si reaction at bombarding energies of 19.7 and 30 MeV/nucleon were measured and interpreted within the Q-optimum model extended by the inclusion of particle evaporation from excited fragments. Regions of forward angle spectra corresponding to the mutual excitation of the reaction partners with net mass transfer zero projected onto the Q-value variable show an enhancement at Q-values of -60 - -80 MeV (excitation energies of the reaction partners equal to 30 - 40 MeV). This energy range coincides with the region of 2ℎω - 3ℎω excitations characteristic for giant osciallations. This selective excitation, which occurs at a very early stage of the reaction (the cross section is the largest at very forward angles), provides an important doorway to other dissipative processes

  2. Dopo il Grande Evento: politiche “utili” per la mobilità Beyond the Mega Events: “Useful” Policies for Urban Mobility

    Directory of Open Access Journals (Sweden)

    Andrea Ceudech

    2008-08-01

    Full Text Available Il contributo indaga i limiti delle politiche urbane e in particolare di quelle sulla mobilità attuate per i Grandi Eventi, evidenziando in molti casi la tendenza a privilegiare la realizzazione di infrastrutture, più che politiche sui servizi, la cui reale utilità è spesso messa in dubbio dalla pratica e i cui costi manutentivi divengono spesso nuovi carichi per la collettività. Sulla base di una breve rassegna delle politiche sulla mobilità maggiormente implementate nella preparazione e gestione dei Grandi Eventi, il contributo evidenzia in maniera critica punti di forza e punti di debolezza delle esperienze analizzate in riferimento sia alla gestione del grande evento, sia in riferimento alla loro reale utilità per la collettività dopo che il grande evento è terminato. Nell’ultima parte del contributo si evidenziano i principali requisiti che le politiche sulla mobilità devono possedere affinché apportino reali vantaggi alla città anche una volta che il Grande Evento è terminato.The paper analyses, through different examples, the limits of the urban mobility policies implemented for mega events, highlighting the tendency to privilege the infrastructure realization, more than policies on services, whose real usefulness is often put in doubt from the practice and whose maintenance often become a new cost for the community. On the base of a short review of the mobility policies mainly implemented in the preparation and management of the mega events, the paper highlights, from a critical point of view, the strengths and weaknesses of some experiences with reference to the real usefulness of urban mobility for the community beyond the mega event. The outcomes and the so-called “legacy” of the mega events for the cities are very different. Mega sport events, like the Olympic Games, have often involved only the realization of works for the event while events like the International Expositions have determined the acquisition of

  3. Microwave joining of SiC

    Energy Technology Data Exchange (ETDEWEB)

    Silberglitt, R.; Ahmad, I. [FM Technologies, Inc., Fairfax, VA (United States); Black, W.M. [George Mason Univ., Fairfax, VA (United States)] [and others

    1995-05-01

    The purpose of this work is to optimize the properties of SiC-SiC joints made using microwave energy. The current focus is on optimization of time-temperature profiles, production of SiC from chemical precursors, and design of new applicators for joining of long tubes.

  4. Oxide Structure Dependence of SiO2/SiOx/3C-SiC/n-Type Si Nonvolatile Resistive Memory on Memory Operation Characteristics

    Science.gov (United States)

    Yamaguchi, Yuichiro; Shouji, Masatsugu; Suda, Yoshiyuki

    2012-11-01

    We have investigated the dependence of the oxide layer structure of our previously proposed metal/SiO2/SiOx/3C-SiC/n-Si/metal metal-insulator-semiconductor (MIS) resistive memory device on the memory operation characteristics. The current-voltage (I-V) measurement and X-ray photoemission spectroscopy results suggest that SiOx defect states mainly caused by the oxidation of 3C-SiC at temperatures below 1000 °C are related to the hysteresis memory behavior in the I-V curve. By restricting the SiOx interface region, the number of switching cycles and the on/off current ratio are more enhanced. Compared with a memory device formed by one-step or two-step oxidation of 3C-SiC, a memory device formed by one-step oxidation of Si/3C-SiC exhibits a more restrictive SiOx interface with a more definitive SiO2 layer and higher memory performances for both the endurance switching cycle and on/off current ratio.

  5. Laser-controlled stress of Si nanocrystals in a free-standing Si /SiO2 superlattice

    Science.gov (United States)

    Khriachtchev, Leonid; Räsänen, Markku; Novikov, Sergei

    2006-01-01

    We report laser manipulations with stress at the nanoscale level. The continuous-wave Ar+ laser radiation melts Si nanocrystals in a free-standing Si /SiO2 superlattice. Silicon crystallization from the liquid phase leads to a compressive stress, which can be accurately tuned in the 3GPa range using laser annealing below the Si melting temperature and then recovered by laser annealing above the melting temperature. This allows investigations of various phenomena as a function of stress and makes a case of Si-nanocrystal memory with very long retention time, which can be written, erased, and read by optical means.

  6. Laser-controlled stress of Si nanocrystals in a free-standing Si/SiO2 superlattice

    International Nuclear Information System (INIS)

    Khriachtchev, Leonid; Raesaenen, Markku; Novikov, Sergei

    2006-01-01

    We report laser manipulations with stress at the nanoscale level. The continuous-wave Ar + laser radiation melts Si nanocrystals in a free-standing Si/SiO 2 superlattice. Silicon crystallization from the liquid phase leads to a compressive stress, which can be accurately tuned in the 3 GPa range using laser annealing below the Si melting temperature and then recovered by laser annealing above the melting temperature. This allows investigations of various phenomena as a function of stress and makes a case of Si-nanocrystal memory with very long retention time, which can be written, erased, and read by optical means

  7. Gas leak tightness of SiC/SiC composites at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Hayasaka, Daisuke, E-mail: hayasaka@oasis.muroran-it.ac.jp [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Park, Joon-Soo. [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Kishimoto, Hirotatsu [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Kohyama, Akira [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan)

    2016-11-01

    Highlights: • NITE-SiC/SiC has extremely densified microstructure compared with other SiC/SiC composite like CVI. • Excellent helium and hydrogen gas-leak tightness of SiC/SiC composites by DEMO-NITE method from prototype industrialization production line was presented. • The excellence against stainless steel and Zircaloy at elevated temperature, together with generic excellent properties of SiC will be inevitable for innovative blanket and divertors for DEMO- and power- fusion reactors. - Abstract: SiC/SiC composite materials are attractive candidates for high heat flux components and blanket of fusion reactor, mainly due to their high temperature properties, radiation damage tolerance and low induced radioactivity. One of the challenges for SiC/SiC application in fusion reactors is to satisfy sufficient gas leak tightness of hydrogen and helium isotopes. Although many efforts have been carried-out, SiC/SiC composites by conventional processes have not been successful to satisfy the requirements, except SiC/SiC composites by NITE-methods. Toward the early realization of SiC/SiC components into fusion reactor systems process development of NITE-process has been continued. Followed to the brief introduction of recently developed DEMO-NITE process, baseline properties and hydrogen and helium gas leak tightness is presented. SiC/SiC claddings with 10 mm in diameter and 1 mm in wall thickness are tested by gas leak tightness system developed. The leak tightness measurements are done room temperature to 400 °C. Excellent gas leak tightness equivalent or superior to Zircaloy claddings for light water fission reactors is confirmed. The excellent gas leak tightness suggests nearly perfect suppression of large gas leak path in DEMO-NITE SiC/SiC.

  8. 3C-SiC nanocrystal growth on 10° miscut Si(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Deokar, Geetanjali, E-mail: gitudeo@gmail.com [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); D' Angelo, Marie; Demaille, Dominique [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); Cavellin, Catherine Deville [INSP, UPMC, CNRS UMR 7588, 4 place Jussieu, Paris F-75005 (France); Faculté des Sciences et Technologie UPEC, 61 av. De Gaulle, Créteil F-94010 (France)

    2014-04-01

    The growth of 3C-SiC nano-crystal (NC) on 10° miscut Si(001) substrate by CO{sub 2} thermal treatment is investigated by scanning and high resolution transmission electron microscopies. The vicinal Si(001) surface was thermally oxidized prior to the annealing at 1100 °C under CO{sub 2} atmosphere. The influence of the atomic steps at the vicinal SiO{sub 2}/Si interface on the SiC NC growth is studied by comparison with the results obtained for fundamental Si(001) substrates in the same conditions. For Si miscut substrate, a substantial enhancement in the density of the SiC NCs and a tendency of preferential alignment of them along the atomic step edges is observed. The SiC/Si interface is abrupt, without any steps and epitaxial growth with full relaxation of 3C-SiC occurs by domain matching epitaxy. The CO{sub 2} pressure and annealing time effect on NC growth is analyzed. The as-prepared SiC NCs can be engineered further for potential application in optoelectronic devices and/or as a seed for homoepitaxial SiC or heteroepitaxial GaN film growth. - Highlights: • Synthesis of 3C-SiC nanocrystals epitaxied on miscut-Si using a simple technique • Evidence of domain matching epitaxy at the SiC/Si interface • SiC growth proceeds along the (001) plane of host Si. • Substantial enhancement of the SiC nanocrystal density due to the miscut • Effect of the process parameters (CO{sub 2} pressure and annealing duration)

  9. Irradiation project of SiC/SiC fuel pin 'INSPIRE': Status and future plan

    International Nuclear Information System (INIS)

    Kohyama, Akira; Kishimoto, Hirotatsu

    2015-01-01

    After the March 11 Disaster in East-Japan, Research and Development towards Ensuring Nuclear Safety Enhancement for LWR becomes a top priority R and D in nuclear energy policy of Japan. The role of high temperature non-metallic materials, such as SiC/SiC, is becoming important for the advanced nuclear reactor systems. SiC fibre reinforced SiC composite has been recognised to be the most attractive option for the future, now, METI fund based project, INSPIRE, has been launched as 5-year termed project at OASIS in Muroran Institute of Technology aiming at early realisation of this system. INSPIRE is the irradiation project of SiC/SiC fuel pins aiming to accumulate material, thermal, irradiation effect data of NITE-SiC/SiC in BWR environment. Nuclear fuel inserted SiC/SiC fuel pins are planned to be installed in the Halden reactor. The project includes preparing the NITE-SiC/SiC tubes, joining of end caps, preparation of rigs to control the irradiation environment to BWR condition and the instruments to measure the condition of rigs and pins in operation. Also, basic neutron irradiation data will be accumulated by SiC/SiC coupon samples currently under irradiation in BR2. The output from this project may present the potentiality of NITE-SiC/SiC fuel cladding with the first stage fuel-cladding interaction. (authors)

  10. Growth of CoSi2 on Si(001) by reactive deposition epitaxy

    International Nuclear Information System (INIS)

    Lim, C.W.; Shin, C.-S.; Gall, D.; Zuo, J.M.; Petrov, I.; Greene, J.E.

    2005-01-01

    CaF 2 -structure CoSi 2 layers were formed on Si(001) by reactive deposition epitaxy (RDE) and compared with CoSi 2 layers obtained by conventional solid phase growth (SPG). In both sets of experiments, Co was deposited by ultrahigh-vacuum magnetron sputtering and CoSi 2 formed at 600 deg. C. However, in the case of RDE, CoSi 2 formation occurred during Co deposition while for SPG, Co was deposited at 25 deg. C and silicidation took place during subsequent annealing. X-ray diffraction pole figures and transmission electron microscopy results demonstrate that RDE CoSi 2 layers are epitaxial with a cube-on-cube relationship (001) CoSi 2 parallel (001) Si and [100] CoSi 2 parallel[100] Si . In contrast, SPG films are polycrystalline with an average grain size of ≅1000 A and a mixed 111/002/022/112 orientation. We attribute the striking difference to rapid Co diffusion into the Si(001) substrate during RDE for which the high Co/Si reactivity gives rise to a flux-limited reaction resulting in the direct formation of the disilicide phase. In contrast, sequential nucleation and transformation among increasingly Si-rich phases--from orthorhombic Co 2 Si to cubic CoSi to CoSi 2 --during SPG results in polycrystalline layers with a complex texture

  11. High resolution investigation of the 30Si(þ, þ)30Si reaction

    NARCIS (Netherlands)

    Walinga, J.; Rinsvelt, H.A. van; Endt, P.M.

    The differential cross section for elastic scattering of protons on 30Si was measured with surface barrier counters at four angles. Thirty-six 30Si(þ, γ)31P resonances are known in the Ep=1–2MeV region. Fifteen of these were also observed in the 30Si(þ, þ)30Si reaction, with natural widths varying

  12. Tunable graphene doping by modulating the nanopore geometry on a SiO2/Si substrate

    KAUST Repository

    Lim, Namsoo; Yoo, Tae Jin; Kim, Jin Tae; Pak, Yusin; Kumaresan, Yogeenth; Kim, Hyeonghun; Kim, Woochul; Lee, Byoung Hun; Jung, Gun Young

    2018-01-01

    A tunable graphene doping method utilizing a SiO2/Si substrate with nanopores (NP) was introduced. Laser interference lithography (LIL) using a He–Cd laser (λ = 325 nm) was used to prepare pore size- and pitch-controllable NP SiO2/Si substrates

  13. Laser cladding of Al-Si/SiC composite coatings : Microstructure and abrasive wear behavior

    NARCIS (Netherlands)

    Anandkumar, R.; Almeida, A.; Vilar, R.; Ocelik, V.; De Hosson, J.Th.M.

    2007-01-01

    Surface coatings of an Al-Si-SiC composite were produced on UNS A03560 cast Al-alloy substrates by laser cladding using a mixture of powders of Al-12 wt.% Si alloy and SiC. The microstructure of the coatings depends considerably on the processing parameters. For a specific energy of 26 MJ/m2 the

  14. Formation of AlFeSi phase in AlSi12 alloy with Ce addition

    Directory of Open Access Journals (Sweden)

    S. Kores

    2012-04-01

    Full Text Available The influence of cerium addition on the solidification sequence and microstructure constituents of the Al-Si alloys with 12,6 mass % Si was examined. The solidification was analyzed by a simple thermal analysis. The microstructures were examined with conventional light and scanning electron microscopy. Ternary AlSiCe phase was formed in the Al-Si alloys with added cerium during the solidification process. AlSiCe and β-AlFeSi phases solidified together in the region that solidified the last. Cerium addition influenced on the morphology of the α-AlFeSi phase solidification.

  15. Abrupt GaP/Si hetero-interface using bistepped Si buffer

    Energy Technology Data Exchange (ETDEWEB)

    Ping Wang, Y., E-mail: yanping.wang@insa-rennes.fr; Kuyyalil, J.; Nguyen Thanh, T.; Almosni, S.; Bernard, R.; Tremblay, R.; Da Silva, M.; Létoublon, A.; Rohel, T.; Tavernier, K.; Le Corre, A.; Cornet, C.; Durand, O. [UMR FOTON, CNRS, INSA Rennes, Rennes F-35708 (France); Stodolna, J.; Ponchet, A. [CEMES-CNRS, Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse Cedex 04 (France); Bahri, M.; Largeau, L.; Patriarche, G. [Laboratoire de Photonique et Nanostructures, CNRS UPR 20, Route de Nozay, Marcoussis 91460 (France); Magen, C. [LMA, INA-ARAID, and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain)

    2015-11-09

    We evidence the influence of the quality of the starting Si surface on the III-V/Si interface abruptness and on the formation of defects during the growth of III-V/Si heterogeneous crystal, using high resolution transmission electron microscopy and scanning transmission electron microscopy. GaP layers were grown by molecular beam epitaxy on vicinal Si (001). The strong effect of the Si substrate chemical preparation is first demonstrated by studying structural properties of both Si homoepitaxial layer and GaP/Si heterostructure. It is then shown that choosing adequate chemical preparation conditions and subsequent III-V regrowth conditions enables the quasi-suppression of micro-twins in the epilayer. Finally, the abruptness of GaP/Si interface is found to be very sensitive to the Si chemical preparation and is improved by the use of a bistepped Si buffer prior to III-V overgrowth.

  16. Abrupt GaP/Si hetero-interface using bistepped Si buffer

    International Nuclear Information System (INIS)

    Ping Wang, Y.; Kuyyalil, J.; Nguyen Thanh, T.; Almosni, S.; Bernard, R.; Tremblay, R.; Da Silva, M.; Létoublon, A.; Rohel, T.; Tavernier, K.; Le Corre, A.; Cornet, C.; Durand, O.; Stodolna, J.; Ponchet, A.; Bahri, M.; Largeau, L.; Patriarche, G.; Magen, C.

    2015-01-01

    We evidence the influence of the quality of the starting Si surface on the III-V/Si interface abruptness and on the formation of defects during the growth of III-V/Si heterogeneous crystal, using high resolution transmission electron microscopy and scanning transmission electron microscopy. GaP layers were grown by molecular beam epitaxy on vicinal Si (001). The strong effect of the Si substrate chemical preparation is first demonstrated by studying structural properties of both Si homoepitaxial layer and GaP/Si heterostructure. It is then shown that choosing adequate chemical preparation conditions and subsequent III-V regrowth conditions enables the quasi-suppression of micro-twins in the epilayer. Finally, the abruptness of GaP/Si interface is found to be very sensitive to the Si chemical preparation and is improved by the use of a bistepped Si buffer prior to III-V overgrowth

  17. Si quantum dot structures and their applications

    Science.gov (United States)

    Shcherbyna, L.; Torchynska, T.

    2013-06-01

    This paper presents briefly the history of emission study in Si quantum dots (QDs) in the last two decades. Stable light emission of Si QDs and NCs was observed in the spectral ranges: blue, green, orange, red and infrared. These PL bands were attributed to the exciton recombination in Si QDs, to the carrier recombination through defects inside of Si NCs or via oxide related defects at the Si/SiOx interface. The analysis of recombination transitions and the different ways of the emission stimulation in Si QD structures, related to the element variation for the passivation of surface dangling bonds, as well as the plasmon induced emission and rare earth impurity activation, have been presented. The different applications of Si QD structures in quantum electronics, such as: Si QD light emitting diodes, Si QD single union and tandem solar cells, Si QD memory structures, Si QD based one electron devices and double QD structures for spintronics, have been discussed as well. Note the significant worldwide interest directed toward the silicon-based light emission for integrated optoelectronics is related to the complementary metal-oxide semiconductor compatibility and the possibility to be monolithically integrated with very large scale integrated (VLSI) circuits. The different features of poly-, micro- and nanocrystalline silicon for solar cells, that is a mixture of both amorphous and crystalline phases, such as the silicon NCs or QDs embedded in a α-Si:H matrix, as well as the thin film 2-cell or 3-cell tandem solar cells based on Si QD structures have been discussed as well. Silicon NC based structures for non-volatile memory purposes, the recent studies of Si QD base single electron devices and the single electron occupation of QDs as an important component to the measurement and manipulation of spins in quantum information processing have been analyzed as well.

  18. Ion beam processes in Si

    International Nuclear Information System (INIS)

    Holland, O.W.; Narayan, J.; Fathy, D.

    1984-07-01

    Observation of the effects of implants of energetic ions at high dose rates into Si have produced some exciting and interesting results. The mechanism whereby displacement damage produced by ions self-anneals during high dose rate implantation is discussed. It is shown that ion beam annealing (IBA) offers in certain situations unique possibilities for damage annealing. Annealing results of the near surface in Si with a buried oxide layer, formed by high dose implantation, are presented in order to illustrate the advantages offered by IBA. It is also shown that ion irradiation can stimulate the epitaxial recrystallization of amorphous overlayers in Si. The nonequilibrium alloying which results from such epitaxial processes is discussed as well as mechanisms which limit the solid solubility during irradiation. Finally, a dose rate dependency for the production of stable damage by ion irradiation at a constant fluence has been observed. For low fluence implants, the amount of damage is substantially greater in the case of high flux rather than low flux implantation

  19. Formation of Si/SiC multilayers by low-energy ion implantation and thermal annealing

    NARCIS (Netherlands)

    Dobrovolskiy, S.; Yakshin, Andrey; Tichelaar, F.D.; Verhoeven, J.; Louis, Eric; Bijkerk, Frederik

    2010-01-01

    Si/SiC multilayer systems for XUV reflection optics with a periodicity of 10–20 nm were produced by sequential deposition of Si and implantation of 1 keV View the MathML source ions. Only about 3% of the implanted carbon was transferred into the SiC, with a thin, 0.5–1 nm, buried SiC layer being

  20. Stability analysis of SiO2/SiC multilayer coatings

    International Nuclear Information System (INIS)

    Fu Zhiqiang; Jean-Charles, R.

    2006-01-01

    The stability behaviours of SiC coatings and SiO 2 /SiC coatings in helium with little impurities are studied by HSC Chemistry 4.1, the software for analysis of Chemical reaction and equilibrium in multi-component complex system. It is found that in helium with a low partial pressure of oxidative impurities under different total pressure, the key influence factor controlling T cp of SiC depends is the partial pressure of oxidative impurities; T cp of SiC increases with the partial pressure of oxidative impurities. In helium with a low partial pressure of different impurities, the key influence factor of T cs of SiO 2 are both the partial pressure of impurities and the amount of impurities for l mol SiO 2 ; T cs of SiO 2 increases with the partial pressure of oxidative impurities at the same amount of the impurities for 1 mol SiO 2 while it decreases with the amount of the impurities for 1 mm SiO 2 at the same partial pressure of the impurities. The influence of other impurities on T cp of SiC in He-O 2 is studied and it is found that CO 2 , H 2 O and N-2 increase T cp of SiC in He-O 2 while H 2 , CO and CH 4 decrease T cp of SiC He-O 2 . When there exist both oxidative impurities and reductive impurities, their effect on T cs of SiO 2 can be suppressed by the other. In HTR-10 operation atmosphere, SiO 2 /SiC coatings can keep stable status at higher temperature than SiC coatings, so SiO 2 /SiC coatings is more suitable to improve the oxidation resistance of graphite in HTR-10 operation atmosphere compared with SiC coatings. (authors)

  1. (113) Facets of Si-Ge/Si Islands; Atomic Scale Simulation

    Science.gov (United States)

    Kassem, Hassan

    We have studied, by computer simulation, some static and vibrationnal proprieties of SiGe/Si islands. We have used a Valence Force Field combined to Monte Carlo technique to study the growth of Ge and SiGe on (001)Si substrates. We have focalised on the case of large pyramidal islands presenting (113) facets on the free (001)Si surface with various non uniform composition inside the islands. The deformation inside the islands and Raman spectroscopy are discussed.

  2. Porous SiC/SiC composites development for industrial application

    International Nuclear Information System (INIS)

    Maeta, S.; Hinoki, T.

    2014-01-01

    Silicon carbide (SiC) is promising structural materials in nuclear fields due to an excellent irradiation resistance and low activation characteristics. Conventional SiC fibers reinforced SiC matrix (SiC/SiC composites) fabricated by liquid phase sintering (LPS-SiC/SiC composites) have been required high cost and long processing time. And microstructure and mechanical property data of finally obtained LPS-SiC/SiC composites are easily scattered, because quality of the composites depend on personal skill. Thus, conventional LPS-SiC/SiC composites are inadequate for industrial use. In order to overcome these issues, the novel “porous SiC/SiC composites” have been developed by means of liquid phase sintering fabrication process. The composites consist of porous SiC matrix and SiC fibers without conventional carbon interfacial layer. The composites don’t have concerns of the degradation interfacial layer at the severe accident. Porous SiC/SiC composites preform was prepared with a thin sheet shape of SiC, sintering additives and carbon powder mixture by tape casting process which was adopted because of productive and high yielding rate fabrication process. The preform was stacked with SiC fibers and sintered in hot-press at the high temperature in argon environment. The sintered preform was decarburized obtain porous matrix structure by heat-treatment in air. Moreover, mechanical property data scattering of the obtained porous SiC/SiC composites decreased. In the flexural test, the porous SiC/SiC composites showed pseudo-ductile behavior with sufficient strength even after heat treatment at high temperature in air. From these conclusions, it was proven that porous SiC/SiC composites were reliable material at severe environment such as high temperature in air, by introducing tape casting fabrication process that could produce reproducible materials with low cost and simple way. Therefore development of porous SiC/SiC composites for industrial application was

  3. Double transparent conducting layers for Si photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Ju-Hyung [Department of Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States); Kim, Joondong, E-mail: joonkim@incheon.ac.kr [Department of Electrical Engineering, Incheon National University, Incheon, 406772 (Korea, Republic of); Park, Yun Chang [Measurement and Analysis Division, National Nanofab Center (NNFC), Daejeon 305806 (Korea, Republic of); Moon, Sang-Jin [Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), Daejeon 305-600 (Korea, Republic of); Anderson, Wayne A. [Department of Electrical Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260 (United States)

    2013-11-29

    Double transparent conductive oxide (TCO) film-embedded Si heterojunction solar cells were fabricated. An intentional doping was not applied for heterojunction solar cells due to the spontaneous Schottky junction formation between TCO films and an n-type Si substrate. Three different TCO coatings were formed by sputtering method for an Al-doped ZnO (AZO) film, an indium-tin-oxide (ITO) film and double stacks of ITO/AZO films. An improved crystalline ITO film was grown on an AZO template upon hetero-epitaxial growth. This double TCO films-embedded Si (ITO/AZO/Si) heterojunction solar cell provided significantly enhanced efficiency of 9.23 % as compared to the single TCO/Si (ITO/Si or AZO/Si) devices due to the optical and the electrical benefits. The effective arrangement of TCO films (ITO/AZO) provides benefits of a lower front contact resistance and a smaller band offset to Si leading enhanced photovoltaic performances. This demonstrates a potential scheme for an effective TCO film-embedded heterojunction Si solar cell. - Highlights: • Double transparent conducting oxide films form a heterojunction to Si. • A quality indium-tin-oxide film was grown above an Al-doped zinc oxide template. • Heterojunction Si solar cell was made without an intentional doping process.

  4. Dynamic behaviors of laser ablated Si particles

    International Nuclear Information System (INIS)

    Ohyanagi, T.; Murakami, K.; Miyashita, A.; Yoda, O.

    1995-01-01

    The dynamics of laser-ablated Si particles produced by laser ablation have been investigated by time-and-space resolved X-ray absorption spectroscopy in a time scale ranging from 0 ns to 120 ns with a time resolution of 10 ns. Neutral and charged particles are observed through all X-ray absorption spectra. Assignments of transitions from 2s and 2p initial states to higher Rydberg states of Si atom and ions are achieved, and we experimentally determine the L II,III absorption edges of neutral Si atom (Si 0 ) and Si + , Si 2+ , Si 3+ and Si 4+ ions. The main ablated particles are found to be Si atom and Si ions in the initial stage of 0 ns to 120 ns. The relative amounts depend strongly on times and laser energy densities. We find that the spatial distributions of particles produced by laser ablation are changed with supersonic helium gas bombardment, but no cluster formation takes place. This suggests that a higher-density region of helium gas is formed at the top of the plume of ablated particles, and free expansion of particles is restrained by this helium cloud, and that it takes more than 120 ns to form Si clusters. (author)

  5. Double transparent conducting layers for Si photovoltaics

    International Nuclear Information System (INIS)

    Yun, Ju-Hyung; Kim, Joondong; Park, Yun Chang; Moon, Sang-Jin; Anderson, Wayne A.

    2013-01-01

    Double transparent conductive oxide (TCO) film-embedded Si heterojunction solar cells were fabricated. An intentional doping was not applied for heterojunction solar cells due to the spontaneous Schottky junction formation between TCO films and an n-type Si substrate. Three different TCO coatings were formed by sputtering method for an Al-doped ZnO (AZO) film, an indium-tin-oxide (ITO) film and double stacks of ITO/AZO films. An improved crystalline ITO film was grown on an AZO template upon hetero-epitaxial growth. This double TCO films-embedded Si (ITO/AZO/Si) heterojunction solar cell provided significantly enhanced efficiency of 9.23 % as compared to the single TCO/Si (ITO/Si or AZO/Si) devices due to the optical and the electrical benefits. The effective arrangement of TCO films (ITO/AZO) provides benefits of a lower front contact resistance and a smaller band offset to Si leading enhanced photovoltaic performances. This demonstrates a potential scheme for an effective TCO film-embedded heterojunction Si solar cell. - Highlights: • Double transparent conducting oxide films form a heterojunction to Si. • A quality indium-tin-oxide film was grown above an Al-doped zinc oxide template. • Heterojunction Si solar cell was made without an intentional doping process

  6. Reliability study of ultra-thin gate oxides on strained-Si/SiGe MOS structures

    International Nuclear Information System (INIS)

    Varzgar, John B.; Kanoun, Mehdi; Uppal, Suresh; Chattopadhyay, Sanatan; Tsang, Yuk Lun; Escobedo-Cousins, Enrique; Olsen, Sarah H.; O'Neill, Anthony; Hellstroem, Per-Erik; Edholm, Jonas; Ostling, Mikael; Lyutovich, Klara; Oehme, Michael; Kasper, Erich

    2006-01-01

    The reliability of gate oxides on bulk Si and strained Si (s-Si) has been evaluated using constant voltage stressing (CVS) to investigate their breakdown characteristics. The s-Si architectures exhibit a shorter life time compared to that of bulk Si, which is attributed to higher bulk oxide charges (Q ox ) and increased surface roughness in the s-Si structures. The gate oxide in the s-Si structure exhibits a hard breakdown (HBD) at 1.9 x 10 4 s, whereas HBD is not observed in bulk Si up to a measurement period of 1.44 x 10 5 s. The shorter lifetime of the s-Si gate oxide is attributed to a larger injected charge (Q inj ) compared to Q inj in bulk Si. Current-voltage (I-V) measurements for bulk Si samples at different stress intervals show an increase in stress induced leakage current (SILC) of two orders in the low voltage regime from zero stress time to up to 5 x 10 4 s. In contrast, superior performance enhancements in terms of drain current, maximum transconductance and effective channel mobility are observed in s-Si MOSFET devices compared to bulk Si. The results from this study indicate that further improvement in gate oxide reliability is needed to exploit the sustained performance enhancement of s-Si devices over bulk Si

  7. Innovative SiC/SiC composite for nuclear applications

    International Nuclear Information System (INIS)

    Chaffron, L.; Sauder, C.; Lorrette, C.; Briottet, L.; Michaux, A.; Gelebart, L.; Coupe, A.; Zabiego, M.; Le Flem, M.; Seran, J. L.

    2013-01-01

    Among various refractory materials, SiC/SiC ceramic matrix composites (CMC) are of prime interest for fusion and advanced fission energy applications, due to their excellent irradiation tolerance and safety features (low activation, low tritium permeability,K). Initially developed as fuel cladding materials for the Fourth generation Gas cooled Fast Reactor (GFR), this material has been recently envisaged by CEA for different core structures of Sodium Fast Reactor (SFR) which combines fast neutrons and high temperature (500 deg.C). Regarding fuel cladding generic application, in the case of GFR, the first challenge facing this project is to demonstrate the feasibility of a fuel operating under very harsh conditions that are (i) temperatures of structures up to 700 deg.C in nominal and over 1600 deg.C in accidental conditions, (ii) irradiation damage higher than 60 dpa SiC , (iii) neutronic transparency, which disqualifies conventional refractory metals as structural core materials, (iv) mechanical behavior that guarantees in most circumstances the integrity of the first barrier (e.g.: ε> 0.5%), which excludes monolithic ceramics and therefore encourages the development of new types of fibrous composites SiC/SiC adapted to the fast reactor conditions. No existing material being capable to match all these requirements, CEA has launched an ambitious program of development of an advanced material satisfying the specifications [1]. This project, that implies many laboratories, inside and outside CEA, has permitted to obtain a very high quality compound that meets most of the challenging requirements. We present hereinafter few recent results obtained regarding the development of the composite. One of the most relevant challenges was to make a gas-tight composite up to the ultimate rupture. Indeed, multi-cracking of the matrix is the counterpart of the damageable behavior observed in these amazing compounds. Among different solutions envisaged, an innovative one has been

  8. Characterization of defects in Si and SiO2-Si using positrons

    International Nuclear Information System (INIS)

    Asoka-Kumar, P.; Lynn, K.G.

    1993-01-01

    Positron annihilation spectroscopy of overlayers, interfaces, and buried regions of semiconductors has seen a rapid growth in recent years. The characteristics of the annihilation gamma rays depend strongly on the local environment of the annihilation sites, and can be used to probe defect concentrations in a range inaccessible to conventional defect probes. Some of the recent success of the technique in examining low concentrations of point defects in technologically important Si-based structures is discussed

  9. MuSiK Projekt:Multimaterialdruck von C/Si/SiC-Keramiken

    OpenAIRE

    Marigo, Gloria; Wahl, Larissa; Nauditt, Gotthard

    2017-01-01

    Poster über den ersten 6 Monate von MuSiK Projekt. Additive Verfahren wurden ursprünglich zur effizienten Herstellung von Mustern und Prototypen entwickelt und bieten besondere Einsatzpotentiale, die mittlerweile auch für die Kleinserienproduktion hochinteressant sind. Im Bereich der keramischen Komponenten ist der Einsatz additiver Verfahren bislang nicht weit verbreitet. Ein Grund dafür ist unter anderem die eingeschränkte Verfügbarkeit der notwendigen Fertigungsanlagen und entsprech...

  10. Formation, structure, and phonon confinement effect of nanocrystalline Si1-xGex in SiO2-Si-Ge cosputtered films

    International Nuclear Information System (INIS)

    Yang, Y.M.; Wu, X.L.; Siu, G.G.; Huang, G.S.; Shen, J.C.; Hu, D.S.

    2004-01-01

    Using magnetron cosputtering of SiO 2 , Ge, and Si targets, Si-based SiO 2 :Ge:Si films were fabricated for exploring the influence of Si target proportion (P Si ) and annealing temperature (Ta) on formation, local structure, and phonon properties of nanocrystalline Si 1-x Ge x (nc-Si 1-x Ge x ). At low P Si and Ta higher than 800 deg. C, no nc-Si 1-x Ge x but a kind of composite nanocrystal consisting of a Ge core, GeSi shell, and amorphous Si outer shell is formed in the SiO 2 matrix. At moderate P Si , nc-Si 1-x Ge x begins to be formed at Ta=800 deg. C and coexists with nc-Ge at Ta=1100 deg. C. At high P Si , it was disclosed that both optical phonon frequency and lattice spacing of nc-Si 1-x Ge x increase with raising Ta. The possible origin of this phenomenon is discussed by considering three factors, the phonon confinement, strain effect, and composition variation of nc-Si 1-x Ge x . This work will be helpful in understanding the growth process of ternary GeSiO films and beneficial to further investigations on optical properties of nc-Ge 1-x Si x in the ternary matrix

  11. Oxidation protection of multilayer CVD SiC/B/SiC coatings for 3D C/SiC composite

    International Nuclear Information System (INIS)

    Liu Yongsheng; Cheng Laifei; Zhang Litong; Wu Shoujun; Li Duo; Xu Yongdong

    2007-01-01

    A CVD boron coating was introduced between two CVD SiC coating layers. EDS and XRD results showed that the CVD B coating was a boron crystal without other impurity elements. SEM results indicated that the CVD B coating was a flake-like or column-like crystal with a compact cross-section. The crack width in the CVD SiC coating deposited on CVD B is smaller than that in a CVD SiC coating deposited on CVD SiC coating. After oxidation at 700 deg. C and 1000 deg. C, XRD results indicated that the coating was covered by product B 2 O 3 or B 2 O 3 .xSiO 2 film. The cracks were sealed as observed by SEM. There was a large amount of flake-like material on hybrid coating surface after oxidation at 1300 deg. C. Oxidation weight loss and residual flexural strength results showed that hybrid SiC/B/SiC multilayer coating provided better oxidation protection for C/SiC composite than a three layer CVD SiC coating at temperatures from 700 deg. C to 1000 deg. C for 600 min, but worse oxidation protection above 1000 deg. C due to the large amount of volatilization of B 2 O 3 or B 2 O 3 .xSiO 2

  12. Mechanical behavior of SiCf/SiC composites with alternating PyC/SiC multilayer interphases

    International Nuclear Information System (INIS)

    Yu, Haijiao; Zhou, Xingui; Zhang, Wei; Peng, Huaxin; Zhang, Changrui

    2013-01-01

    Highlights: ► Superior combination of flexural strength and fracture toughness of the 3D SiC/SiC composite was achieved by interface tailoring. ► Resulted composite possesses a much higher flexural strength and fracture toughness than its counterparts in literatures. ► Mechanisms that PyC/SiC multilayer coatings improve the mechanical properties were illustrated. -- Abstract: In order to tailor the fiber–matrix interface of continuous silicon carbide fiber reinforced silicon carbide (SiC f /SiC) composites for improved fracture toughness, alternating pyrolytic carbon/silicon carbide (PyC/SiC) multilayer coatings were applied to the KD-I SiC fibers using chemical vapor deposition (CVD) method. Three dimensional (3D) KD-I SiC f /SiC composites reinforced by these coated fibers were fabricated using a precursor infiltration and pyrolysis (PIP) process. The interfacial characteristics were determined by the fiber push-out test and microstructural examination using scanning electron microscopy (SEM). The effect of interface coatings on composite mechanical properties was evaluated by single-edge notched beam (SENB) test and three-point bending test. The results indicate that the PyC/SiC multilayer coatings led to an optimum interfacial bonding between fibers and matrix and greatly improved the fracture toughness of the composites.

  13. An Isotope Study of Hydrogenation of poly-Si/SiOx Passivated Contacts for Si Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Schnabel, Manuel; Nemeth, William; van de Loo, Bas, W.H.; Macco, Bart; Kessels, Wilhelmus, M.M.; Stradins, Paul; Young, David, L.

    2017-06-26

    For many years, the record Si solar cell efficiency stood at 25.0%. Only recently have several companies and institutes managed to produce more efficient cells, using passivated contacts of made doped poly-Si or a-Si:H and a passivating intrinsic interlayer in all cases. Common to these designs is the need to passivate the layer stack with hydrogen. In this contribution, we perform a systematic study of passivated contact passivation by hydrogen, using poly-Si/SiOx passivated contacts on n-Cz-Si, and ALD Al2O3 followed by a forming gas anneal (FGA) as the hydrogen source. We study p-type and n-type passivated contacts with implied Voc exceeding 690 and 720 mV, respectively, and perform either the ALD step or the FGA with deuterium instead of hydrogen in order to separate the two processes via SIMS. By examining the deuterium concentration at the SiOx in both types of samples, we demonstrate that the FGA supplies negligible hydrogen species to the SiOx, regardless of whether the FGA is hydrogenated or deuterated. Instead, it supplies the thermal energy needed for hydrogen species in the Al2O3 to diffuse there. Furthermore, the concentration of hydrogen species at the SiOx can saturate while implied Voc continues to increase, showing that the energy from the FGA is also required for hydrogen species already at the SiOx to find recombination-active defects to passivate.

  14. Fiber/matrix interfaces for SiC/SiC composites: Multilayer SiC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, H.; Curtin, W.A. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)

    1996-08-01

    Tensile tests have been performed on composites of CVI SiC matrix reinforced with 2-d Nicalon fiber cloth, with either pyrolitic carbon or multilayer CVD SiC coatings [Hypertherm High-Temperature Composites Inc., Huntington Beach, CA.] on the fibers. To investigate the role played by the different interfaces, several types of measurements are made on each sample: (i) unload-reload hysteresis loops, and (ii) acoustic emission. The pyrolitic carbon and multilayer SiC coated materials are remarkably similar in overall mechanical responses. These results demonstrate that low-modulus, or compliant, interface coatings are not necessary for good composite performance, and that complex, hierarchical coating structures may possibly yield enhanced high-temperature performance. Analysis of the unload/reload hysteresis loops also indicates that the usual {open_quotes}proportional limit{close_quotes} stress is actually slightly below the stress at which the 0{degrees} load-bearing fibers/matrix interfaces slide and are exposed to atmosphere.

  15. Determination of optimum Si excess concentration in Er-doped Si-rich SiO2 for optical amplification at 1.54 μm

    International Nuclear Information System (INIS)

    Savchyn, Oleksandr; Coffey, Kevin R.; Kik, Pieter G.

    2010-01-01

    The presence of indirect Er 3+ excitation in Si-rich SiO 2 is demonstrated for Si-excess concentrations in the range of 2.5-37 at. %. The Si excess concentration providing the highest density of sensitized Er 3+ ions is demonstrated to be relatively insensitive to the presence of Si nanocrystals and is found to be ∼14.5 at. % for samples without Si nanocrystals (annealed at 600 deg. C) and ∼11.5 at. % for samples with Si nanocrystals (annealed at 1100 deg. C). The observed optimum is attributed to an increase in the density of Si-related sensitizers as the Si concentration is increased, with subsequent deactivation and removal of these sensitizers at high Si concentrations. The optimized Si excess concentration is predicted to generate maximum Er-related gain at 1.54 μm in devices based on Er-doped Si-rich SiO 2 .

  16. High-performance a -Si/c-Si heterojunction photoelectrodes for photoelectrochemical oxygen and hydrogen evolution

    KAUST Repository

    Wang, Hsin Ping

    2015-05-13

    Amorphous Si (a-Si)/crystalline Si (c-Si) heterojunction (SiHJ) can serve as highly efficient and robust photoelectrodes for solar fuel generation. Low carrier recombination in the photoelectrodes leads to high photocurrents and photovoltages. The SiHJ was designed and fabricated into both photoanode and photocathode with high oxygen and hydrogen evolution efficiency, respectively, by simply coating of a thin layer of catalytic materials. The SiHJ photoanode with sol-gel NiOx as the catalyst shows a current density of 21.48 mA/cm2 at the equilibrium water oxidation potential. The SiHJ photocathode with 2 nm sputter-coated Pt catalyst displays excellent hydrogen evolution performance with an onset potential of 0.640 V and a solar to hydrogen conversion efficiency of 13.26%, which is the highest ever reported for Si-based photocathodes. © 2015 American Chemical Society.

  17. Propagation of misfit dislocations from buffer/Si interface into Si

    Science.gov (United States)

    Liliental-Weber, Zuzanna [El Sobrante, CA; Maltez, Rogerio Luis [Porto Alegre, BR; Morkoc, Hadis [Richmond, VA; Xie, Jinqiao [Raleigh, VA

    2011-08-30

    Misfit dislocations are redirected from the buffer/Si interface and propagated to the Si substrate due to the formation of bubbles in the substrate. The buffer layer growth process is generally a thermal process that also accomplishes annealing of the Si substrate so that bubbles of the implanted ion species are formed in the Si at an appropriate distance from the buffer/Si interface so that the bubbles will not migrate to the Si surface during annealing, but are close enough to the interface so that a strain field around the bubbles will be sensed by dislocations at the buffer/Si interface and dislocations are attracted by the strain field caused by the bubbles and move into the Si substrate instead of into the buffer epi-layer. Fabrication of improved integrated devices based on GaN and Si, such as continuous wave (CW) lasers and light emitting diodes, at reduced cost is thereby enabled.

  18. Comparative study of anisotropic superconductivity in CaAlSi and CaGaSi

    International Nuclear Information System (INIS)

    Tamegai, T.; Uozato, K.; Kasahara, S.; Nakagawa, T.; Tokunaga, M.

    2005-01-01

    In order to get some insight into the origin of the anomalous angular dependence of H c2 in a layered intermetallic compound CaAlSi, electronic, superconducting, and structural properties are compared between CaAlSi and CaGaSi. The angular dependence of H c2 in CaGaSi is well described by the anisotropic GL model. Parallel to this finding, the pronounced lattice modulation accompanying the superstructure along the c-axis in CaAlSi is absent in CaGaSi. A relatively large specific heat jump at the superconducting transition in CaAlSi compared with CaGaSi indicates the presence of strong electron-phonon coupling in CaAlSi, which may cause the superstructure and the anomalous angular dependence of H c2

  19. Switching Performance Evaluation of Commercial SiC Power Devices (SiC JFET and SiC MOSFET) in Relation to the Gate Driver Complexity

    DEFF Research Database (Denmark)

    Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    and JFETs. The recent introduction of SiC MOSFET has proved that it is possible to have highly performing SiC devices with a minimum gate driver complexity; this made SiC power devices even more attractive despite their device cost. This paper presents an analysis based on experimental results...... of the switching losses of various commercially available Si and SiC power devices rated at 1200 V (Si IGBTs, SiC JFETs and SiC MOSFETs). The comparison evaluates the reduction of the switching losses which is achievable with the introduction of SiC power devices; this includes analysis and considerations...

  20. Interfacial stability of CoSi2/Si structures grown by molecular beam epitaxy

    Science.gov (United States)

    George, T.; Fathauer, R. W.

    1992-01-01

    The stability of CoSi2/Si interfaces was examined in this study using columnar silicide structures grown on (111) Si substrates. In the first set of experiments, Co and Si were codeposited using MBE at 800 C and the resulting columnar silicide layer was capped by epitaxial Si. Deposition of Co on the surface of the Si capping layer at 800 C results in the growth of the buried silicide columns. The buried columns grow by subsurface diffusion of the deposited Co, suppressing the formation of surface islands of CoSi2. The column sidewalls appear to be less stable than the top and bottom interfaces, resulting in preferential lateral growth and ultimately in the coalescence of the columns to form a continuous buried CoSi2 layer. In the second set of experiments, annealing of a 250 nm-thick buried columnar layer at 1000 C under a 100 nm-thick Si capping layer results in the formation of a surface layer of CoSi2 with a reduction in the sizes of the CoSi2 columns. For a sample having a thicker Si capping layer the annealing leads to Ostwald ripening producing buried equiaxed columns. The high CoSi2/Si interfacial strain could provide the driving force for the observed behavior of the buried columns under high-temperature annealing.

  1. C-H and C-C activation of n -butane with zirconium hydrides supported on SBA15 containing N-donor ligands: [(≡SiNH-)(≡SiX-)ZrH2], [(≡SiNH-)(≡SiX-)2ZrH], and[(≡SiN=)(≡SiX-)ZrH] (X = -NH-, -O-). A DFT study

    KAUST Repository

    Pasha, Farhan Ahmad; Bendjeriou-Sedjerari, Anissa; Huang, Kuo-Wei; Basset, Jean-Marie

    2014-01-01

    : [(≡SiNH-)(≡SiO-)ZrH2] (A), [(≡SiNH-)2ZrH2] (B), [(≡SiNH-)(≡SiO-) 2ZrH] (C), [(≡SiNH-)2(≡SiO-)ZrH] (D), [(≡SiN=)(≡Si-O-)ZrH] (E), and [(≡SiN=)(≡SiNH-)ZrH] (F). The roles of these hydrides have been investigated in C-H/C-C bond activation and cleavage

  2. Impact resistance of uncoated SiC/SiC composites

    International Nuclear Information System (INIS)

    Bhatt, Ramakrishna T.; Choi, Sung R.; Cosgriff, Laura M.; Fox, Dennis S.; Lee, Kang N.

    2008-01-01

    Two-dimensional woven SiC/SiC composites fabricated by melt infiltration method were impact tested at room temperature and at 1316 deg. C in air using 1.59-mm diameter steel-ball projectiles at velocities ranging from 115 to 400 m/s. The extent of substrate damage with increasing projectile velocity was imaged and analyzed using optical and scanning electron microscopy, and non-destructive evaluation (NDE) methods such as pulsed thermography, and computed tomography. The impacted specimens were tensile tested at room temperature to determine their residual mechanical properties. Results indicate that at 115 m/s projectile velocity, the composite showed no noticeable surface or internal damage and retained its as-fabricated mechanical properties. As the projectile velocity increased above this value, the internal damage increased and mechanical properties degraded. At velocities >300 m/s, the projectile penetrated through the composite, but the composite retained ∼50% of the ultimate tensile strength of the as-fabricated composite and exhibited non-brittle failure. Predominant internal damages are delamination of fiber plies, fiber fracture and matrix shearing

  3. Effect of germanium concentrations on tunnelling current calculation of Si/Si1-xGex/Si heterojunction bipolar transistor

    Science.gov (United States)

    Hasanah, L.; Suhendi, E.; Khairrurijal

    2018-05-01

    Tunelling current calculation on Si/Si1-xGex/Si heterojunction bipolar transistor was carried out by including the coupling between transversal and longitudinal components of electron motion. The calculation results indicated that the coupling between kinetic energy in parallel and perpendicular to S1-xGex barrier surface affected tunneling current significantly when electron velocity was faster than 1x105 m/s. This analytical tunneling current model was then used to study how the germanium concentration in base to Si/Si1-xGex/Si heterojunction bipolar transistor influenced the tunneling current. It is obtained that tunneling current increased as the germanium concentration given in base decreased.

  4. Nanocrystalline Si pathway induced unipolar resistive switching behavior from annealed Si-rich SiN{sub x}/SiN{sub y} multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xiaofan; Ma, Zhongyuan, E-mail: zyma@nju.edu.cn; Yang, Huafeng; Yu, Jie; Wang, Wen; Zhang, Wenping; Li, Wei; Xu, Jun; Xu, Ling; Chen, Kunji; Huang, Xinfan; Feng, Duan [National Laboratory of Solid State Microstructures, Jiangsu Provincial Key Laboratory of Photonic Electronic Materials Sciences and Technology, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China)

    2014-09-28

    Adding a resistive switching functionality to a silicon microelectronic chip is a new challenge in materials research. Here, we demonstrate that unipolar and electrode-independent resistive switching effects can be realized in the annealed Si-rich SiN{sub x}/SiN{sub y} multilayers with high on/off ratio of 10{sup 9}. High resolution transmission electron microscopy reveals that for the high resistance state broken pathways composed of discrete nanocrystalline silicon (nc-Si) exist in the Si nitride multilayers. While for the low resistance state the discrete nc-Si regions is connected, forming continuous nc-Si pathways. Based on the analysis of the temperature dependent I-V characteristics and HRTEM photos, we found that the break-and-bridge evolution of nc-Si pathway is the origin of resistive switching memory behavior. Our findings provide insights into the mechanism of the resistive switching behavior in nc-Si films, opening a way for it to be utilized as a material in Si-based memories.

  5. Influence of substrate treatment on the growth of advanced core–shell alloys and compounds of FeSi@SiO2 and SiO2 nanowires

    CSIR Research Space (South Africa)

    Thabethe, S

    2014-12-01

    Full Text Available Advanced core–shell FeSi@SiO(subx) nanowires are observed when FeCl(sub3) vapour is made to flow over a SiO(sub2)/Si substrate at 1100 degress C. The thickness of the SiO(subx) sheath (d0) is found to depend inversely as the period of time of HF...

  6. Analyse de l’effet du type de tâche sur l’évolution des connaissances à la suite d’un processus d’apprentissage collaboratif

    Directory of Open Access Journals (Sweden)

    Sabine Pohl

    2009-04-01

    Full Text Available L’article analyse l’effet du type de tâche sur le partage des connaissances à la suite d’un processus d’interaction dans un contexte d’apprentissage collaboratif. Cet apprentissage collaboratif est réalisé dans le cadre d’une formation universitaire. Deux types de tâches sont réalisés par les apprenants. Ils se distinguent selon que la solution nécessite ou non la confrontation de points de vue portant sur le champ conceptuel lié à l’apprentissage à réaliser. La méthode de collecte des données consiste en un entretien semi-directif. Les résultats montrent un effet du type de tâches sur l’évolution des connaissances partagées des apprenants.This longitudinal research analyses the effect of the type of task on the development of knowledge following an interaction process in a collaborative learning context. The framework for this collaborative learning is a university education. Two types of tasks are provided to the learners. They differ depending on whether or not the solution requires the comparison of points of view on the conceptual scope of what is to be learned. The data are collected through a semi-directive interview. The results show that the type of task has an effect on the development of shared knowledge.

  7. William Franke, Sulla verità poetica che è superiore alla Storia: Porfirio e la critica filosofica della letteratura William Franke, On the Poetic Truth that is Higher than History: Porphyry and the Philosophical Interpretation of Literature

    Directory of Open Access Journals (Sweden)

    Laura Lucia Rossi

    2010-06-01

    Full Text Available

    In this article we propose the translation of William Franke’s paper On the Poetic Truth that is Higher than History: Porphyry and the Philosophical Criticism of Literature, in which the American scholar presents the hermeneutic method of the ancient commentators of Homer, with particular reference to the critic practice applied by the Neoplatonic Porphyry in his De Antro Nympharum. With this treatment Franke proposes and hopes for the return to an interpretive method, called philosophical or speculative, also for contemporary criticism.

    In questo articolo è presentata la traduzione del saggio di William Franke Sulla verità poetica che è superiore alla Storia: Porfirio e la critica filosofica della letteratura, in cui lo studioso americano presenta il metodo ermeneutico degli antichi commentatori di Omero, con particolare riferimento alla critica praticata dal neoplatonico Porfirio, proponendo e auspicando il ritorno ad una modalità interpretativa, detta filosofica o speculativa, anche per la critica contemporanea.

  8. Effects of C+ ion implantation on electrical properties of NiSiGe/SiGe contacts

    International Nuclear Information System (INIS)

    Zhang, B.; Yu, W.; Zhao, Q.T.; Buca, D.; Breuer, U.; Hartmann, J.-M.; Holländer, B.; Mantl, S.; Zhang, M.; Wang, X.

    2013-01-01

    We have investigated the morphology and electrical properties of NiSiGe/SiGe contact by C + ions pre-implanted into relaxed Si 0.8 Ge 0.2 layers. Cross-section transmission electron microscopy revealed that both the surface and interface of NiSiGe were improved by C + ions implantation. In addition, the effective hole Schottky barrier heights (Φ Bp ) of NiSiGe/SiGe were extracted. Φ Bp was observed to decrease substantially with an increase in C + ion implantation dose

  9. Si K-edge XANES study of SiOxCyHz amorphous polymeric materials

    International Nuclear Information System (INIS)

    Chaboy, J.; Barranco, A.; Yanguas-Gil, A.; Yubero, F.; Gonzalez-Elipe, A. R.

    2007-01-01

    This work reports on x-ray absorption spectroscopy study at the Si K edge of several amorphous SiO x C y H z polymers prepared by plasma-enhanced chemical-vapor deposition with different C/O ratios. SiO 2 and SiC have been used as reference materials. The comparison of the experimental Si K-edge x-ray absorption near-edge structure spectra with theoretical computations based on multiple scattering theory has allowed us to monitor the modification of the local coordination around Si as a function of the overall C/O ratio in this kind of materials

  10. An optically controlled SiC lateral power transistor based on SiC/SiCGe super junction structure

    International Nuclear Information System (INIS)

    Pu Hongbin; Cao Lin; Ren Jie; Chen Zhiming; Nan Yagong

    2010-01-01

    An optically controlled SiC/SiCGe lateral power transistor based on superjunction structure has been proposed, in which n-SiCGe/p-SiC superjunction structure is employed to improve device figure of merit. Performance of the novel optically controlled power transistor was simulated using Silvaco Atlas tools, which has shown that the device has a very good response to the visible light and the near infrared light. The optoelectronic responsivities of the device at 0.5 μm and 0.7 μm are 330 mA/W and 76.2 mA/W at 2 V based voltage, respectively. (semiconductor devices)

  11. An optically controlled SiC lateral power transistor based on SiC/SiCGe super junction structure

    Energy Technology Data Exchange (ETDEWEB)

    Pu Hongbin; Cao Lin; Ren Jie; Chen Zhiming; Nan Yagong, E-mail: puhongbin@xaut.edu.c [Xi' an University of Technology, Xi' an 710048 (China)

    2010-04-15

    An optically controlled SiC/SiCGe lateral power transistor based on superjunction structure has been proposed, in which n-SiCGe/p-SiC superjunction structure is employed to improve device figure of merit. Performance of the novel optically controlled power transistor was simulated using Silvaco Atlas tools, which has shown that the device has a very good response to the visible light and the near infrared light. The optoelectronic responsivities of the device at 0.5 {mu}m and 0.7 {mu}m are 330 mA/W and 76.2 mA/W at 2 V based voltage, respectively. (semiconductor devices)

  12. Interfacial microstructure of NiSi x/HfO2/SiO x/Si gate stacks

    International Nuclear Information System (INIS)

    Gribelyuk, M.A.; Cabral, C.; Gusev, E.P.; Narayanan, V.

    2007-01-01

    Integration of NiSi x based fully silicided metal gates with HfO 2 high-k gate dielectrics offers promise for further scaling of complementary metal-oxide- semiconductor devices. A combination of high resolution transmission electron microscopy and small probe electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis has been applied to study interfacial reactions in the undoped gate stack. NiSi was found to be polycrystalline with the grain size decreasing from top to bottom of NiSi x film. Ni content varies near the NiSi/HfO x interface whereby both Ni-rich and monosilicide phases were observed. Spatially non-uniform distribution of oxygen along NiSi x /HfO 2 interface was observed by dark field Scanning Transmission Electron Microscopy and EELS. Interfacial roughness of NiSi x /HfO x was found higher than that of poly-Si/HfO 2 , likely due to compositional non-uniformity of NiSi x . No intermixing between Hf, Ni and Si beyond interfacial roughness was observed

  13. Effect of PECVD SiNx/SiOy Nx –Si interface property on surface passivation of silicon wafer

    International Nuclear Information System (INIS)

    Jia Xiao-Jie; Zhou Chun-Lan; Zhou Su; Wang Wen-Jing; Zhu Jun-Jie

    2016-01-01

    It is studied in this paper that the electrical characteristics of the interface between SiO y N x /SiN x stack and silicon wafer affect silicon surface passivation. The effects of precursor flow ratio and deposition temperature of the SiO y N x layer on interface parameters, such as interface state density Di t and fixed charge Q f , and the surface passivation quality of silicon are observed. Capacitance–voltage measurements reveal that inserting a thin SiO y N x layer between the SiN x and the silicon wafer can suppress Q f in the film and D it at the interface. The positive Q f and D it and a high surface recombination velocity in stacks are observed to increase with the introduced oxygen and minimal hydrogen in the SiO y N x film increasing. Prepared by deposition at a low temperature and a low ratio of N 2 O/SiH 4 flow rate, the SiO y N x /SiN x stacks result in a low effective surface recombination velocity (S eff ) of 6 cm/s on a p-type 1 Ω·cm–5 Ω·cm FZ silicon wafer. The positive relationship between S eff and D it suggests that the saturation of the interface defect is the main passivation mechanism although the field-effect passivation provided by the fixed charges also make a contribution to it. (paper)

  14. Magnetron-sputter epitaxy of β-FeSi2(220)/Si(111) and β-FeSi2(431)/Si(001) thin films at elevated temperatures

    International Nuclear Information System (INIS)

    Liu Hongfei; Tan Chengcheh; Chi Dongzhi

    2012-01-01

    β-FeSi 2 thin films have been grown on Si(111) and Si(001) substrates by magnetron-sputter epitaxy at 700 °C. On Si(111), the growth is consistent with the commonly observed orientation of [001]β-FeSi 2 (220)//[1-10]Si(111) having three variants, in-plane rotated 120° with respect to one another. However, on Si(001), under the same growth conditions, the growth is dominated by [-111]β-FeSi 2 (431)//[110]Si(001) with four variants, which is hitherto unknown for growing β-FeSi 2 . Photoelectron spectra reveal negligible differences in the valance-band and Fe2p core-level between β-FeSi 2 grown on Si(111) and Si(001) but an apparent increased Si-oxidization on the surface of β-FeSi 2 /Si(001). This phenomenon is discussed and attributed to the Si-surface termination effect, which also suggests that the Si/Fe ratio on the surface of β-FeSi 2 (431)/Si(001) is larger than that on the surface of β-FeSi 2 (220)/Si(111).

  15. Matrix densification of SiC composites by sintering process

    International Nuclear Information System (INIS)

    Kim, Young-Wook; Jang, Doo-Hee; Eom, Jung-Hye; Chun, Yong-Seong

    2007-02-01

    The objectives of this research are to develop a process for dense SiC fiber-SiC composites with a porosity of 5% or less and to develop high-strength SiC fiber-SiC composites with a strength of 500 MPa or higher. To meet the above objectives, the following research topics were investigated ; new process development for the densification of SiC fiber-SiC composites, effect of processing parameters on densification of SiC fiber-SiC composites, effect of additive composition on matrix microstructure, effects of additive composition and content on densification of SiC fiber-SiC composites, mechanical properties of SiC fiber-SiC composites, effect of fiber coating on densification and strength of SiC fiber-SiC composites, development of new additive composition. There has been a great deal of progress in the development of technologies for the processing and densification of SiC fiber-SiC composites and in better understanding of additive-densification-mechanical property relations as results of this project. Based on the progress, dense SiC fiber-SiC composites (≥97%) and high strength SiC fiber-SiC composites (≥600 MPa) have been developed. Development of 2D SiC fiber-SiC composites with a relative density of ≥97% and a strength of ≥600 MPa can be counted as a notable achievement

  16. Photoelectric Properties of Si Doping Superlattice Structure on 6H-SiC(0001).

    Science.gov (United States)

    Li, Lianbi; Zang, Yuan; Hu, Jichao; Lin, Shenghuang; Chen, Zhiming

    2017-05-25

    The energy-band structure and visible photoelectric properties of a p/n-Si doping superlattice structure (DSL) on 6H-SiC were simulated by Silvaco-TCAD. The,n the Si-DSL structures with 40 nm-p-Si/50 nm-n-Si multilayers were successfully prepared on 6H-SiC(0001) Si-face by chemical vapor deposition. TEM characterizations of the p/n-Si DSL confirmed the epitaxial growth of the Si films with preferred orientation and the misfit dislocations with a Burgers vector of 1/3 at the p-Si/n-Si interface. The device had an obvious rectifying behavior, and the turn-on voltage was about 1.2 V. Under the visible illumination of 0.6 W/cm², the device demonstrated a significant photoelectric response with a photocurrent density of 2.1 mA/cm². Visible light operation of the Si-DSL/6H-SiC heterostructure was realized for the first time.

  17. Photoelectric Properties of Si Doping Superlattice Structure on 6H-SiC(0001

    Directory of Open Access Journals (Sweden)

    Lianbi Li

    2017-05-01

    Full Text Available The energy-band structure and visible photoelectric properties of a p/n-Si doping superlattice structure (DSL on 6H-SiC were simulated by Silvaco-TCAD. The,n the Si-DSL structures with 40 nm-p-Si/50 nm-n-Si multilayers were successfully prepared on 6H-SiC(0001 Si-face by chemical vapor deposition. TEM characterizations of the p/n-Si DSL confirmed the epitaxial growth of the Si films with preferred orientation and the misfit dislocations with a Burgers vector of 1/3 <21-1> at the p-Si/n-Si interface. The device had an obvious rectifying behavior, and the turn-on voltage was about 1.2 V. Under the visible illumination of 0.6 W/cm2, the device demonstrated a significant photoelectric response with a photocurrent density of 2.1 mA/cm2. Visible light operation of the Si-DSL/6H-SiC heterostructure was realized for the first time.

  18. Electrical resistivity and thermal conductivity of SiC/Si ecoceramics prepared from sapele wood biocarbon

    Science.gov (United States)

    Parfen'eva, L. S.; Orlova, T. S.; Smirnov, B. I.; Smirnov, I. A.; Misiorek, H.; Mucha, J.; Jezowski, A.; Gutierrez-Pardo, A.; Ramirez-Rico, J.

    2012-10-01

    Samples of β-SiC/Si ecoceramics with a silicon concentration of ˜21 vol % have been prepared using a series of consecutive procedures (carbonization of sapele wood biocarbon, synthesis of high-porosity biocarbon with channel-type pores, infiltration of molten silicon into empty channels of the biocarbon, formation of β-SiC, and retention of residual silicon in channels of β-SiC). The electrical resistivity ρ and thermal conductivity κ of the β-SiC/Si ecoceramic samples have been measured in the temperature range 5-300 K. The values of ρ{Si/chan}( T) and κ{Si/chan}( T) have been determined for silicon Sichan located in β-SiC channels of the synthesized β-SiC/Si ecoceramics. Based on the performed analysis of the obtained results, the concentration of charge carriers (holes) in Sichan has been estimated as p ˜ 1019 cm-3. The factors that can be responsible for such a high value of p have been discussed. The prospects for practical application of β-SiC/Si ecoceramics have been considered.

  19. Polarized luminescence of nc-Si-SiO x nanostructures on silicon substrates with patterned surface

    Science.gov (United States)

    Michailovska, Katerina; Mynko, Viktor; Indutnyi, Ivan; Shepeliavyi, Petro

    2018-05-01

    Polarization characteristics and spectra of photoluminescence (PL) of nc-Si-SiO x structures formed on the patterned and plane c-Si substrates are studied. The interference lithography with vacuum chalcogenide photoresist and anisotropic wet etching are used to form a periodic relief (diffraction grating) on the surface of the substrates. The studied nc-Si-SiO x structures were produced by oblique-angle deposition of Si monoxide in vacuum and the subsequent high-temperature annealing. The linear polarization memory (PM) effect in PL of studied structure on plane substrate is manifested only after the treatment of the structures in HF and is explained by the presence of elongated Si nanoparticles in the SiO x nanocolumns. But the PL output from the nc-Si-SiO x structure on the patterned substrate depends on how this radiation is polarized with respect to the grating grooves and is much less dependent on the polarization of the exciting light. The measured reflection spectra of nc-Si-SiO x structure on the patterned c-Si substrate confirmed the influence of pattern on the extraction of polarized PL.

  20. Sintering Behavior of Spark Plasma Sintered SiC with Si-SiC Composite Nanoparticles Prepared by Thermal DC Plasma Process

    Science.gov (United States)

    Yu, Yeon-Tae; Naik, Gautam Kumar; Lim, Young-Bin; Yoon, Jeong-Mo

    2017-11-01

    The Si-coated SiC (Si-SiC) composite nanoparticle was prepared by non-transferred arc thermal plasma processing of solid-state synthesized SiC powder and was used as a sintering additive for SiC ceramic formation. Sintered SiC pellet was prepared by spark plasma sintering (SPS) process, and the effect of nano-sized Si-SiC composite particles on the sintering behavior of micron-sized SiC powder was investigated. The mixing ratio of Si-SiC composite nanoparticle to micron-sized SiC was optimized to 10 wt%. Vicker's hardness and relative density was increased with increasing sintering temperature and holding time. The relative density and Vicker's hardness was further increased by reaction bonding using additional activated carbon to the mixture of micron-sized SiC and nano-sized Si-SiC. The maximum relative density (97.1%) and Vicker's hardness (31.4 GPa) were recorded at 1800 °C sintering temperature for 1 min holding time, when 0.2 wt% additional activated carbon was added to the mixture of SiC/Si-SiC.

  1. Sintering Behavior of Spark Plasma Sintered SiC with Si-SiC Composite Nanoparticles Prepared by Thermal DC Plasma Process.

    Science.gov (United States)

    Yu, Yeon-Tae; Naik, Gautam Kumar; Lim, Young-Bin; Yoon, Jeong-Mo

    2017-11-25

    The Si-coated SiC (Si-SiC) composite nanoparticle was prepared by non-transferred arc thermal plasma processing of solid-state synthesized SiC powder and was used as a sintering additive for SiC ceramic formation. Sintered SiC pellet was prepared by spark plasma sintering (SPS) process, and the effect of nano-sized Si-SiC composite particles on the sintering behavior of micron-sized SiC powder was investigated. The mixing ratio of Si-SiC composite nanoparticle to micron-sized SiC was optimized to 10 wt%. Vicker's hardness and relative density was increased with increasing sintering temperature and holding time. The relative density and Vicker's hardness was further increased by reaction bonding using additional activated carbon to the mixture of micron-sized SiC and nano-sized Si-SiC. The maximum relative density (97.1%) and Vicker's hardness (31.4 GPa) were recorded at 1800 °C sintering temperature for 1 min holding time, when 0.2 wt% additional activated carbon was added to the mixture of SiC/Si-SiC.

  2. Chemical compatibility issues associated with use of SiC/SiC in advanced reactor concepts

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Dane F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-01

    Silicon carbide/silicon carbide (SiC/SiC) composites are of interest for components that will experience high radiation fields in the High Temperature Gas Cooled Reactor (HTGR), the Very High Temperature Reactor (VHTR), the Sodium Fast Reactor (SFR), or the Fluoride-cooled High-temperature Reactor (FHR). In all of the reactor systems considered, reactions of SiC/SiC composites with the constituents of the coolant determine suitability of materials of construction. The material of interest is nuclear grade SiC/SiC composites, which consist of a SiC matrix [high-purity, chemical vapor deposition (CVD) SiC or liquid phase-sintered SiC that is crystalline beta-phase SiC containing small amounts of alumina-yttria impurity], a pyrolytic carbon interphase, and somewhat impure yet crystalline beta-phase SiC fibers. The interphase and fiber components may or may not be exposed, at least initially, to the reactor coolant. The chemical compatibility of SiC/SiC composites in the three reactor environments is highly dependent on thermodynamic stability with the pure coolant, and on reactions with impurities present in the environment including any ingress of oxygen and moisture. In general, there is a dearth of information on the performance of SiC in these environments. While there is little to no excess Si present in the new SiC/SiC composites, the reaction of Si with O2 cannot be ignored, especially for the FHR, in which environment the product, SiO2, can be readily removed by the fluoride salt. In all systems, reaction of the carbon interphase layer with oxygen is possible especially under abnormal conditions such as loss of coolant (resulting in increased temperature), and air and/ or steam ingress. A global outline of an approach to resolving SiC/SiC chemical compatibility concerns with the environments of the three reactors is presented along with ideas to quickly determine the baseline compatibility performance of SiC/SiC.

  3. Grégory Quenet, 2005, Les Tremblements de terre aux dix-septième et dix-huitième siècles. La naissance d’un risque, Seyssel, Champ Vallon, 587 p.

    Directory of Open Access Journals (Sweden)

    Stéphane Callens

    2005-06-01

    Full Text Available A la question «  Qu’est-ce que les Lumières ? », des réponses inadéquates sont souvent apportées : le dix-huitième siècle aurait été ce moment charnière, privilégiant un idéal d’assujettissement du monde naturel, prélude aux catastrophes du monde industriel. Cette historiographie naïve est battue en brèche dans l’ouvrage de Grégory Quenet consacré à la naissance d’un risque, le risque sismique. Grégory Quenet est un historien qui a travaillé à la vérification des données sismiques pour la Fra...

  4. siRNA and innate immunity.

    Science.gov (United States)

    Robbins, Marjorie; Judge, Adam; MacLachlan, Ian

    2009-06-01

    Canonical small interfering RNA (siRNA) duplexes are potent activators of the mammalian innate immune system. The induction of innate immunity by siRNA is dependent on siRNA structure and sequence, method of delivery, and cell type. Synthetic siRNA in delivery vehicles that facilitate cellular uptake can induce high levels of inflammatory cytokines and interferons after systemic administration in mammals and in primary human blood cell cultures. This activation is predominantly mediated by immune cells, normally via a Toll-like receptor (TLR) pathway. The siRNA sequence dependency of these pathways varies with the type and location of the TLR involved. Alternatively nonimmune cell activation may also occur, typically resulting from siRNA interaction with cytoplasmic RNA sensors such as RIG1. As immune activation by siRNA-based drugs represents an undesirable side effect due to the considerable toxicities associated with excessive cytokine release in humans, understanding and abrogating this activity will be a critical component in the development of safe and effective therapeutics. This review describes the intracellular mechanisms of innate immune activation by siRNA, the design of appropriate sequences and chemical modification approaches, and suitable experimental methods for studying their effects, with a view toward reducing siRNA-mediated off-target effects.

  5. SiD Letter of Intent

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, H., (Ed.); Burrows, P., (Ed.); Oreglia, M., (Ed.); Berger, E.L.; Guarino, V.; Repond, J.; Weerts, H.; Xia, L.; Zhang, J.; /Argonne, HEP; Zhang, Q.; /Argonne, HEP /Beijing, Inst. High Energy Phys.; Srivastava, A.; /Birla Inst. Tech. Sci.; Butler, J.M.; /Boston U.; Goldstein, Joel; Velthuis, J.; /Bristol U.; Radeka, V.; /Brookhaven; Zhu, R.-Y.; /Caltech.; Lutz, P.; /DAPNIA, Saclay; de Roeck, A.; Elsener, K.; Gaddi, A.; Gerwig, H.; /CERN /Cornell U., LNS /Ewha Women' s U., Seoul /Fermilab /Gent U. /Darmstadt, GSI /Imperial Coll., London /Barcelona, Inst. Microelectron. /KLTE-ATOMKI /Valencia U., IFIC /Cantabria Inst. of Phys. /Louis Pasteur U., Strasbourg I /Durham U., IPPP /Kansas State U. /Kyungpook Natl. U. /Annecy, LAPP /LLNL, Livermore /Louisiana Tech. U. /Paris U., VI-VII /Paris U., VI-VII /Munich, Max Planck Inst. /MIT, LNS /Chicago, CBC /Moscow State U. /Nanjing U. /Northern Illinois U. /Obninsk State Nucl. Eng. U. /Paris U., VI-VII /Strasbourg, IPHC /Prague, Inst. Phys. /Princeton U. /Purdue U. /Rutherford /SLAC /SUNY, Stony Brook /Barcelona U. /Bonn U. /UC, Davis /UC, Santa Cruz /Chicago U. /Colorado U. /Delhi U. /Hawaii U. /Helsinki U. /Indiana U. /Iowa U. /Massachusetts U., Amherst /Melbourne U. /Michigan U. /Minnesota U. /Mississippi U. /Montenegro U. /New Mexico U. /Notre Dame U. /Oregon U. /Oxford U. /Ramon Llull U., Barcelona /Rochester U. /Santiago de Compostela U., IGFAE /Hefei, CUST /Texas U., Arlington /Texas U., Dallas /Tokyo U. /Washington U., Seattle /Wisconsin U., Madison /Wayne State U. /Yale U. /Yonsei U.

    2012-04-11

    This document presents the current status of the Silicon Detector (SiD) effort to develop an optimized design for an experiment at the International Linear Collider. It presents detailed discussions of each of SiD's various subsystems, an overview of the full GEANT4 description of SiD, the status of newly developed tracking and calorimeter reconstruction algorithms, studies of subsystem performance based on these tools, results of physics benchmarking analyses, an estimate of the cost of the detector, and an assessment of the detector R and D needed to provide the technical basis for an optimised SiD.

  6. Thermogravimetric and microscopic analysis of SiC/SiC materials with advanced interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, C.F. Jr.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States); Snead, L.L. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    The chemical stability of SiC/SiC composites with fiber/matrix interfaces consisting of multilayers of SiC/SiC and porous SiC have been evaluated using a thermal gravimetric analyzer (TGA). Previous evaluations of SiC/SiC composites with carbon interfacial layers demonstrated the layers are not chemically stable at goal use temperatures of 800-1100{degrees}C and O{sub 2} concentrations greater than about 1 ppm. No measureable mass change was observed for multilayer and porous SiC interfaces at 800-1100{degrees}C and O{sub 2} concentrations of 100 ppm to air; however, the total amount of oxidizable carbon is on the order of the sensitivity of the TGA. Further studies are in progress to evaluate the stability of these materials.

  7. Characterization of SiC–SiC composites for accident tolerant fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Deck, C.P., E-mail: Christian.Deck@ga.com; Jacobsen, G.M.; Sheeder, J.; Gutierrez, O.; Zhang, J.; Stone, J.; Khalifa, H.E.; Back, C.A.

    2015-11-15

    Silicon carbide (SiC) is being investigated for accident tolerant fuel cladding applications due to its high temperature strength, exceptional stability under irradiation, and reduced oxidation compared to Zircaloy under accident conditions. An engineered cladding design combining monolithic SiC and SiC–SiC composite layers could offer a tough, hermetic structure to provide improved performance and safety, with a failure rate comparable to current Zircaloy cladding. Modeling and design efforts require a thorough understanding of the properties and structure of SiC-based cladding. Furthermore, both fabrication and characterization of long, thin-walled SiC–SiC tubes to meet application requirements are challenging. In this work, mechanical and thermal properties of unirradiated, as-fabricated SiC-based cladding structures were measured, and permeability and dimensional control were assessed. In order to account for the tubular geometry of the cladding designs, development and modification of several characterization methods were required.

  8. Mechanism of Si intercalation in defective graphene on SiC

    KAUST Repository

    Kaloni, Thaneshwor P.; Cheng, Yingchun; Schwingenschlö gl, Udo; Upadhyay Kahaly, M.

    2012-01-01

    Previously reported experimental findings on Si-intercalated graphene on SiC(0001) seem to indicate the possibility of an intercalation process based on the migration of the intercalant through atomic defects in the graphene sheet. We employ density

  9. Formation mechanism of SiC in C-Si system by ion irradiation

    International Nuclear Information System (INIS)

    Hishita, Shunichi; Aizawa, Takashi; Suehara, Shigeru; Haneda, Hajime

    2003-01-01

    The irradiation effects of 2 MeV He + , Ne + , and Ar + ions on the film structure of the C-Si system were investigated with RHEED and XPS. The ion dose dependence of the SiC formation was kinetically analyzed. The SiC formation at moderate temperature was achieved by 2 MeV ion irradiation when the thickness of the initial carbon films was appropriate. The evolution process of the SiC film thickness consisted of the 3 stages. The first stage was the steep increase of the SiC, and was governed by the inelastic collision. The second was the gentle increase of the SiC, and was governed by the diffusion. The last was the decrease of the SiC, and was caused by the sputtering. The formation mechanism of the SiC was discussed. (author)

  10. Surface Chemistry Involved in Epitaxy of Graphene on 3C-SiC(111/Si(111

    Directory of Open Access Journals (Sweden)

    Abe Shunsuke

    2010-01-01

    Full Text Available Abstract Surface chemistry involved in the epitaxy of graphene by sublimating Si atoms from the surface of epitaxial 3C-SiC(111 thin films on Si(111 has been studied. The change in the surface composition during graphene epitaxy is monitored by in situ temperature-programmed desorption spectroscopy using deuterium as a probe (D2-TPD and complementarily by ex situ Raman and C1s core-level spectroscopies. The surface of the 3C-SiC(111/Si(111 is Si-terminated before the graphitization, and it becomes C-terminated via the formation of C-rich (6√3 × 6√3R30° reconstruction as the graphitization proceeds, in a similar manner as the epitaxy of graphene on Si-terminated 6H-SiC(0001 proceeds.

  11. Dielectric Properties of SiCf/PyC/SiC Composites After Oxidation

    Institute of Scientific and Technical Information of China (English)

    SONG Huihui; ZHOU Wancheng; LUO Fa; QING Yuchang; CHEN Malin; LI Zhimin

    2016-01-01

    In this paper, the SiC fiber-reinforced SiC matrix composites with a 0.15mm thick pyrocarbon interphase (notedas SiCf/PyC/SiC) were prepared by chemical vapor infiltration (CVI). The SiCf/PyC/SiC were oxidized in air at 950℃ for 50h. The dielectric properties after this high temperature oxidation were investigated in X-band from room temperature (RT) to 700℃. Results suggested that:e' of the SiCf/PyC/SiC after oxidation increased at first then de-creased with temperature elevating;e" increased with temperature raising in the temperature range studied.

  12. Fermi surfaces of YRu2Si2 and LaRu2Si2

    International Nuclear Information System (INIS)

    Settai, R.; Ikezawa, H.; Toshima, H.; Takashita, M.; Ebihara, T.; Sugawara, H.; Kimura, T.; Motoki, K.; Onuki, Y.

    1995-01-01

    We have measured the de Haas-van Alphen effect of YRu 2 Si 2 and LaRu 2 Si 2 to clarify the Fermi surfaces and cyclotron masses. Main hole-Fermi surfaces of both compounds with a distorted ellipsoid shape are similar, occupying about half of the Brillouin zone. The small hole-Fermi surfaces with the shape of a rugby ball are three in number for LaRu 2 Si 2 , and one for YRu 2 Si 2 . An electron-Fermi surface consists of a doughnut like shape for LaRu 2 Si 2 , while a cylinder along the [001] direction and a multiply-connected shape exist for YRu 2 Si 2 . The cyclotron masses of YRu 2 Si 2 are a little larger than those of LaRu 2 Si 2 . ((orig.))

  13. A sensitive optical sensor based on DNA-labelled Si@SiO2 core ...

    Indian Academy of Sciences (India)

    2017-10-31

    Oct 31, 2017 ... Si@SiO2 core–shell nanoparticles were proposed for the development of fluorescent mercury ... orophores, due to their unique optical properties, such as .... were made by evaporating one drop of the sample solution on.

  14. Ni-Si oxide as an inducing crystallization source for making poly-Si

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Zhiguo; Liu, Zhaojun; Li, Juan; Wu, Chunya; Xiong, Shaozhen [Institute of Photo-electronics, Nankai University, Tianjin (China); Zhao, Shuyun; Wong, Man; Kwok, Hoi Sing [Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Kowloon, Hong Kong (China)

    2010-04-15

    Nickel silicon oxide mixture was sputtered on a-Si with Ni-Si alloy target with Ni:Si weight ratio of 1:9 and used as a new inducing source for metal induced lateral crystallization (MILC). The characteristics of the resulted poly-Si materials induced by Ni-Si oxide with different thickness were nearly the same. This means the metal induced crystallization with this new inducing source has wide processing tolerance to make MILC poly-Si. Besides, it reduced the residual Ni content in the resulted poly-Si film. The transfer characteristic curve of poly-Si TFT and a TFT-OLED display demo made with this kind of new inducing source were also presented in this paper. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Rod-like β-FeSi2 phase grown on Si (111) substrate

    International Nuclear Information System (INIS)

    Han Ming; Tanaka, Miyoko; Takeguchi, Masaki; Furuya, Kazuo

    2004-01-01

    Pure Fe with coverage of 0.5-2.0 nm was deposited on Si (111) 7x7 surfaces by reactive deposition epitaxy (RDE) in an integrated ultrahigh vacuum (UHV) system. Transmission electron microscopy (TEM) confirmed that the as-deposited epitaxial phase exhibits rod-like and equilateral triangular morphology. The as-deposited phase was identified as c-FeSi 2 by electron diffraction and high-resolution transmission electron microscopy. It was found that there exists lattice distortion in epitaxial c-FeSi 2 phase. Upon annealing at 1073 K, the metastable c-FeSi 2 transforms into equilibrium β-FeSi 2 phase, the latter inherits completely the morphology of c-FeSi 2 phase. Based on RDE and subsequent annealing, a new fabrication technique to grow rod-like semiconducting β-FeSi 2 on a Si substrate has been proposed in the present work

  16. Development of SiC/SiC composite for fusion application

    International Nuclear Information System (INIS)

    Kohyama, A.; Katoh, Y.; Snead, L.L.; Jones, R.H.

    2001-01-01

    The recent efforts to develop SiC/SiC composite materials for fusion application under the collaboration with Japan and the USA are provided, where material performance with and without radiation damage has been greatly improved. One of the accomplishments is development of the high performance reaction sintering process. Mechanical and thermal conductivity are improved extensively by process modification and optimization with inexpensive fabrication process. The major efforts to make SiC matrix by CVI, PIP and RS methods are introduced together with the representing baseline properties. The resent results on mechanical properties of SiC/SiC under neutron irradiation are quite positive. The composites with new SiC fibers, Hi-Nicalon Type-S, did not exhibit mechanical property degradation up to 10 dpa. Based on the materials data recently obtained, a very preliminary design window is provided and the future prospects of SiC/SiC technology integration is provided. (author)

  17. Superficial biopsy of the cervix: new technique

    Directory of Open Access Journals (Sweden)

    Ettore De Girolami

    2002-06-01

    Full Text Available Cytological examination of the cervix in all patients is considered a necessity. A new technique of superficial biopsy is described and advantages en. numeratedEl Autor presenta una nueva técnica para biopsia superficial, considerando la necesidad de hacer rutinariamente a todas las pacientes el examen citológico del cérvix. La muestra se toma con el extremo de un aplicador cubierto de gaza. Este dispositivo, humedecido previamente en una solución de etanol, metanol y éter etílico, se aplica inmediatamente al cérvix del útero y, dándole un movimiento como el de las manecillas del reloj, se toma la muestra con la que se hacen frotis por aposición que se colorean por el método de Giemsa. Esta técnica ofrece la ventaja de que el tejido en estudio se adhiere perfectamente a la gaza, la cual, con el movimiento de rotación, desprende las células del "os uteri", las que son fijadas al mismo tiempo. La preparación del dispositivo es sumamente sencilla. La prueba resulta de bajo costo como de breve y fácil realizaciónL' Autore prende in considerazione l'utilitá dell' esame citologico del collo dell'utero, fatto rutinariamente a tutte le pazienti. Si descrive una nuova tecnica di biopsia superficiale che oltfe ad offrire dei vantaggi é di poca spesa e si puó eseguire con facilitá ed in breve tempo

  18. Effect of irradiation on thermal expansion of SiCf/SiC composites

    International Nuclear Information System (INIS)

    Senor, D.J.; Trimble, D.J.; Woods, J.J.

    1996-06-01

    Linear thermal expansion was measured on five different SiC-fiber-reinforced/SiC-matrix (SiC f /SiC) composite types in the unirradiated and irradiated conditions. Two matrices were studied in combination with Nicalon CG reinforcement and a 150 nm PyC fiber/matrix interface: chemical vapor infiltrated (CVI) SiC and liquid-phase polymer impregnated precursor (PIP) SiC. Composites of PIP SiC with Tyranno and HPZ fiber reinforcement and a 150 nm PyC interface were also tested, as were PIP SiC composites with Nicalon CG reinforcement and a 150 nm BN fiber/matrix interface. The irradiation was conducted in the Experimental Breeder Reactor-II at a nominal temperature of 1,000 C to doses of either 33 or 43 dpa-SiC. Irradiation caused complete fiber/matrix debonding in the CVI SiC composites due to a dimensional stability mismatch between fiber and matrix, while the PIP SiC composites partially retained their fiber/matrix interface after irradiation. However, the thermal expansion of all the materials tested was found to be primarily dependent on the matrix and independent of either the fiber or the fiber/matrix interface. Further, irradiation had no significant effect on thermal expansion for either the CVI SiC or PIP SiC composites. In general, the thermal expansion of the CVI SiC composites exceeded that of the PIP SiC composites, particularly at elevated temperatures, but the expansion of both matrix types was less than chemical vapor deposited (CVD) β-SiC at all temperatures

  19. Hybrid Integrated Si/SiN Platforms for Wideband Optical Processing

    Science.gov (United States)

    2017-05-08

    annealing process, makes the process prone to dopant redistribution, that hinderers the SiN deposition after full Si device fabrication. To resolve...with 220 nm of crystalline Si. In parallel, a Si die goes through a wet oxidation process to grow 5 μm of thermal oxide. In the next step, 400 nm of... annealing methods. As a figure of merit in hydrophilic bonding, we monitored the surface roughness and bonding strength of a thin oxide layer to

  20. Formation of ferromagnetic interface between β-FeSi2 and Si(111) substrate

    International Nuclear Information System (INIS)

    Hattori, Azusa N.; Hattori, Ken; Kodama, Kenji; Hosoito, Nobuyoshi; Daimon, Hiroshi

    2007-01-01

    Epitaxial β-FeSi 2 thin films were grown on Si(111)7x7 clean surfaces by solid phase epitaxy in ultrahigh vacuum: iron deposition at low temperature and subsequent annealing. We found that a ferromagnetic interface layer of iron-rich silicides forms between a β-FeSi 2 surface layer and a Si(111) substrate spontaneously from transmission electron microscopy observations and magnetization measurements

  1. Minimum bar size for flexure testing of irradiated SiC/SiC composite

    International Nuclear Information System (INIS)

    Youngblood, G.E.; Jones, R.H.

    1998-01-01

    This report covers material presented at the IEA/Jupiter Joint International Workshop on SiC/SiC Composites for Fusion structural Applications held in conjunction with ICFRM-8, Sendai, Japan, Oct. 23-24, 1997. The minimum bar size for 4-point flexure testing of SiC/SiC composite recommended by PNNL for irradiation effects studies is 30 x 6 x 2 mm 3 with a span-to-depth ratio of 10/1

  2. Passivation of surface-nanostructured f-SiC and porous SiC

    DEFF Research Database (Denmark)

    Ou, Haiyan; Lu, Weifang; Ou, Yiyu

    The further enhancement of photoluminescence from nanostructured fluorescent silicon carbide (f-SiC) and porous SiC by using atomic layer deposited (ALD) Al2O3 is studied in this paper.......The further enhancement of photoluminescence from nanostructured fluorescent silicon carbide (f-SiC) and porous SiC by using atomic layer deposited (ALD) Al2O3 is studied in this paper....

  3. Formation of Si/SiC multilayers by low-energy ion implantation and thermal annealing

    NARCIS (Netherlands)

    Dobrovolskiy, S.; Yakshin, A. E.; Tichelaar, F. D.; Verhoeven, J.; E. Louis,; F. Bijkerk,

    2010-01-01

    Si/SiC multilayer systems for XUV reflection optics with a periodicity of 10-20 nm were produced by sequential deposition of Si and implantation of 1 key CHx+ ions. Only about 3% of the implanted carbon was transferred into the SIC, with a thin, 0.5-1 nm, buried SIC layer being formed. We

  4. Thermal Stability of siRNA Modulates Aptamer- conjugated siRNA Inhibition

    Directory of Open Access Journals (Sweden)

    Alexey Berezhnoy

    2012-01-01

    Full Text Available Oligonucleotide aptamer-mediated in vivo cell targeting of small interfering RNAs (siRNAs is emerging as a useful approach to enhance the efficacy and reduce the adverse effects resulting from siRNA-mediated genetic interference. A current main impediment in aptamer-mediated siRNA targeting is that the activity of the siRNA is often compromised when conjugated to an aptamer, often requiring labor intensive and time consuming design and testing of multiple configurations to identify a conjugate in which the siRNA activity has not been significantly reduced. Here, we show that the thermal stability of the siRNA is an important parameter of siRNA activity in its conjugated form, and that siRNAs with lower melting temperature (Tm are not or are minimally affected when conjugated to the 3′ end of 2′F-pyrimidine-modified aptamers. In addition, the configuration of the aptamer-siRNA conjugate retains activity comparable with the free siRNA duplex when the passenger strand is co-transcribed with the aptamer and 3′ overhangs on the passenger strand are removed. The approach described in this paper significantly reduces the time and effort necessary to screening siRNA sequences that retain biological activity upon aptamer conjugation, facilitating the process of identifying candidate aptamer-siRNA conjugates suitable for in vivo testing.

  5. siRNAmod: A database of experimentally validated chemically modified siRNAs.

    Science.gov (United States)

    Dar, Showkat Ahmad; Thakur, Anamika; Qureshi, Abid; Kumar, Manoj

    2016-01-28

    Small interfering RNA (siRNA) technology has vast potential for functional genomics and development of therapeutics. However, it faces many obstacles predominantly instability of siRNAs due to nuclease digestion and subsequently biologically short half-life. Chemical modifications in siRNAs provide means to overcome these shortcomings and improve their stability and potency. Despite enormous utility bioinformatics resource of these chemically modified siRNAs (cm-siRNAs) is lacking. Therefore, we have developed siRNAmod, a specialized databank for chemically modified siRNAs. Currently, our repository contains a total of 4894 chemically modified-siRNA sequences, comprising 128 unique chemical modifications on different positions with various permutations and combinations. It incorporates important information on siRNA sequence, chemical modification, their number and respective position, structure, simplified molecular input line entry system canonical (SMILES), efficacy of modified siRNA, target gene, cell line, experimental methods, reference etc. It is developed and hosted using Linux Apache MySQL PHP (LAMP) software bundle. Standard user-friendly browse, search facility and analysis tools are also integrated. It would assist in understanding the effect of chemical modifications and further development of stable and efficacious siRNAs for research as well as therapeutics. siRNAmod is freely available at: http://crdd.osdd.net/servers/sirnamod.

  6. Tunable Synthesis of SiC/SiO2 Heterojunctions via Temperature Modulation

    Directory of Open Access Journals (Sweden)

    Wei Li

    2018-05-01

    Full Text Available A large-scale production of necklace-like SiC/SiO2 heterojunctions was obtained by a molten salt-mediated chemical vapor reaction technique without a metallic catalyst or flowing gas. The effect of the firing temperature on the evolution of the phase composition, microstructure, and morphology of the SiC/SiO2 heterojunctions was studied. The necklace-like SiC/SiO2 nanochains, several centimeters in length, were composed of SiC/SiO2 core-shell chains and amorphous SiO2 beans. The morphologies of the as-prepared products could be tuned by adjusting the firing temperature. In fact, the diameter of the SiO2 beans decreased, whereas the diameter of the SiC fibers and the thickness of the SiO2 shell increased as the temperature increased. The growth mechanism of the necklace-like structure was controlled by the vapor-solid growth procedure and the modulation procedure via a molten salt-mediated chemical vapor reaction process.

  7. Status and prospects for SiC-SiC composite materials development for fusion applications

    International Nuclear Information System (INIS)

    Sharafat, S.; Jones, R.H.; Kohyama, A.; Fenici, P.

    1995-01-01

    Silicon carbide (SiC) composites are very attractive for fusion applications because of their low afterheat and low activation characteristics coupled with excellent high temperature properties. These composites are relatively new materials that will require material development as well as evaluation of hermiticity, thermal conductivity, radiation stability, high temperature strength, fatigue, thermal shock, and joining techniques. The radiation stability of SiC-SiC composites is a critical aspect of their application as fusion components and recent results will be reported. Many of the non-fusion specific issues are under evaluation by other ceramic composite development programs, such as the US national continuous fiber ceramic composites.The current development status of various SiC-SiC composites research and development efforts is given. Effect of neutron irradiation on the properties of SiC-SiC composite between 500 and 1200 C are reported. Novel high temperature properties specific to ceramic matrix composite (CMC) materials are discussed. The chemical stability of SiC is reviewed briefly. Ongoing research and development efforts for joining CMC materials including SiC-SiC composites are described. In conclusion, ongoing research and development efforts show extremely promising properties and behavior for SiC-SiC composites for fusion applications. (orig.)

  8. Thermochemical instability effects in SiC-based fibers and SiC{sub f}/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Henager, C.H.; Jones, R.H. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1997-08-01

    Thermochemical instability in irradiated SiC-based fibers with an amorphous silicon oxycarbide phase leads to shrinkage and mass loss. SiC{sub f}/SiC composites made with these fibers also exhibit mass loss as well as severe mechanical property degradation when irradiated at 800{degrees}C, a temperature much below the generally accepted 1100{degrees}C threshold for thermomechanical degradation alone. The mass loss is due to an internal oxidation mechanism within these fibers which likely degrades the carbon interphase as well as the fibers in SiC{sub f}/SiC composites even in so-called {open_quotes}inert{close_quotes} gas environments. Furthermore, the mechanism must be accelerated by the irradiation environment.

  9. Dall’inferno si leva un canto. Italo Calvino e «l’eco lontana del silenzio»

    Directory of Open Access Journals (Sweden)

    Andrea Cannas

    2015-07-01

    Full Text Available Nella produzione narrativa di Italo Calvino l’explicit può circoscrivere lo spazio verso cui il 'rumore' del mondo s’avanza a minacciare l’ordine della finzione – e, viceversa, il finale dell’opera può risultare l’ultimo baluardo per mezzo del quale il senso, di cui la finzione è la più strenua attestazione, si sforza di resistere al non senso che proviene dal caos della Storia. Il cielo di pietra, Un re in ascolto, racconti dedicati al valore del canto e, per contro, alla minaccia acustica scoperchiata dalle indiavolate metropoli del nostro tempo, insieme all’epilogo de Le città invisibili rappresentano tre casi emblematici in cui la finzione digrada verso la realtà marcando, su un piano finalmente sincronico, l’estrema frontiera da cui l’autore contempla la propria comunità d’appartenenza – ed eventualmente riflette sul potere, se non salvifico, per lo meno discriminante della parola scritta. Da questa prospettiva il silenzio è al contempo il presupposto e il movimento cui dovrebbe tendere ogni scrittura: costituisce in definitiva per Calvino l’opportunità di discernere per cogliere finalmente l’essenziale.

  10. Addimer diffusions on Si(100)

    International Nuclear Information System (INIS)

    Lee, Gun Do; Wang, C. Z.; Lu, Z. Y.; Ho, K. M.

    1999-01-01

    The diffusion pathways along the trough and between the trough and the dimer row on the Si(100) surface are investigated by tight-binding molecular dynamics calculations using the environment dependent tight-binding silicon potential and by ab initio calculations using the Car-Parrinello method. The studies discover new diffusion pathways consisting of rotation of addimer. The calculated energy barrier are in excellent agreement with experiment. The rotational diffusion pathway between the trough and the dimer row is much more energetically favorable than other diffusion pathways by parallel and perpendicular addimer. The new pathway along the trough is nearly same as the energy barrier of the diffusion pathway by dissociation of the addimer

  11. Tunneling magnetoresistance in Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    2016-11-09

    We investigate the tunneling magnetoresistance of small diameter semiconducting Si nanowires attached to ferromagnetic Fe electrodes, using first principles density functional theory combined with the non-equilibrium Green\\'s functions method for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we systematically study the spin transport properties for neutral nanowires and both n and p doping conditions. We find a substantial low bias magnetoresistance for the neutral case, which halves for an applied voltage of about 0.35 V and persists up to 1 V. Doping in general decreases the magnetoresistance, as soon as the conductance is no longer dominated by tunneling.

  12. Transformation of sludge Si to nano-Si/SiOx structure by oxygen inward diffusion as precursor for high performance anodes in lithium ion batteries

    Science.gov (United States)

    Hua, Qiqi; Dai, Dongyang; Zhang, Chengzhi; Han, Fei; Lv, Tiezheng; Li, Xiaoshan; Wang, Shijie; Zhu, Rui; Liao, Haojie; Zhang, Shiguo

    2018-05-01

    Although several Si/C composite structures have been proposed for high-performance lithium-ion batteries (LIBs), they have still suffered from expensive and complex processes of nano-Si production. Herein, a simple, controllable oxygen inward diffusion was utilized to transform Si sludge obtained from the photovoltaic (PV) industry into the nano-Si/SiOx structure as a result of the high diffusion efficiency of O inside Si and high surface area of the sludge. After further process, a yolk/shell Si/C structure was obtained as an anode material for LIBs. This composite demonstrated an excellent cycling stability, with a high reversible capacity (˜ 1250 mAh/g for 500 cycles), by void space originally left by the SiOx accommodate inner Si expansion. We believe this is a rather simple way to convert the waste Si into a valuable nano-Si for LIB applications.

  13. Formation of metallic Si and SiC nanoparticles from SiO2 particles by plasma-induced cathodic discharge electrolysis in chloride melt

    International Nuclear Information System (INIS)

    Tokushige, M.; Tsujimura, H.; Nishikiori, T.; Ito, Y.

    2013-01-01

    Silicon nanoparticles are formed from SiO 2 particles by conducting plasma-induced cathodic discharge electrolysis. In a LiCl–KCl melt in which SiO 2 particles were suspended at 450 °C, we obtained Si nanoparticles with diameters around 20 nm. During the electrolysis period, SiO 2 particles are directly reduced by discharge electrons on the surface of the melt just under the discharge, and the deposited Si atom clusters form Si nanoparticles, which leave the surface of the original SiO 2 particle due to free spaces caused by a molar volume difference between SiO 2 and Si. We also found that SiC nanoparticles can be obtained using carbon anode. Based on Faraday's law, the current efficiency for the formation of Si nanoparticles is 70%

  14. SI konkurss / Anna Roomet

    Index Scriptorium Estoniae

    Roomet, Anna

    2006-01-01

    Konkursist, auhinnatseremooniast ja ekspositsioonist Arhitektuuri- ja Disainigaleriis, žürii koosseis. Intervjuu eesti parima noore disaineri preemia SÄSI pälvinud Pavel Sidorenko ning väikese SÄSI saanud Björn Koobi, Ülle Jehe ja Igor Volkoviga

  15. Intranasal delivery of antiviral siRNA.

    Science.gov (United States)

    Barik, Sailen

    2011-01-01

    Intranasal administration of synthetic siRNA is an effective modality of RNAi delivery for the prevention and therapy of respiratory diseases, including pulmonary infections. Vehicles used for nasal siRNA delivery include established as well as novel reagents, many of which have been recently optimized. In general, they all promote significant uptake of siRNA into the lower respiratory tract, including the lung. When properly designed and optimized, these siRNAs offer significant protection against respiratory viruses such as influenza virus, parainfluenza virus and respiratory syncytial virus (RSV). Nasally administered siRNA remains within the lung and does not access systemic blood flow, as judged by its absence in other major organs such as liver, heart, kidney, and skeletal muscle. Adverse immune reaction is generally not encountered, especially when immunogenic and/or off-target siRNA sequences and toxic vehicles are avoided. In fact, siRNA against RSV has entered Phase II clinical trials in human with promising results. Here, we provide a standardized procedure for using the nose as a specific route for siRNA delivery into the lung of laboratory animals. It should be clear that this simple and efficient system has enormous potential for therapeutics.

  16. Self-aligned indium–gallium–zinc oxide thin-film transistors with SiNx/SiO2/SiNx/SiO2 passivation layers

    International Nuclear Information System (INIS)

    Chen, Rongsheng; Zhou, Wei; Zhang, Meng; Kwok, Hoi-Sing

    2014-01-01

    Self-aligned top-gate amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) with SiN x /SiO 2 /SiN x /SiO 2 passivation layers are developed in this paper. The resulting a-IGZO TFT exhibits high reliability against bias stress and good electrical performance including field-effect mobility of 5 cm 2 /Vs, threshold voltage of 2.5 V, subthreshold swing of 0.63 V/decade, and on/off current ratio of 5 × 10 6 . With scaling down of the channel length, good characteristics are also obtained with a small shift of the threshold voltage and no degradation of subthreshold swing. The proposed a-IGZO TFTs in this paper can act as driving devices in the next generation flat panel displays. - Highlights: • Self-aligned top-gate indium–gallium–zinc oxide thin-film transistor is proposed. • SiN x /SiO 2 /SiN x /SiO 2 passivation layers are developed. • The source/drain areas are hydrogen-doped by CHF3 plasma. • The devices show good electrical performance and high reliability against bias stress

  17. Back-contacted BaSi

    NARCIS (Netherlands)

    Vismara, R.; Isabella, O.; Zeman, M.

    2017-01-01

    We present the optical investigation of a novel back-contacted architecture for solar cells based on a thin barium (di)silicide (BaSi2) absorber. First, through the analysis of absorption limits of different semiconducting materials, we show the potential of BaSi2 for

  18. Natural 32Si as environmental tracer

    International Nuclear Information System (INIS)

    Morgenstern, U.

    2005-01-01

    There is a pressing need for an effective dating tool to cover the historical past. Cosmogenic 32 Si, with a half-life of ca. 140 years, is ideally suited to provide time information in the range 50-1000 years. Detection of 32 Si is, however, very difficult due to extremely low natural concentrations and isotopic ratios. (author). 2 refs

  19. SHS synthesis of Si-SiC composite powders using Mg and reactants from industrial waste

    Science.gov (United States)

    Chanadee, Tawat

    2017-11-01

    Si-SiC composite powders were synthesized by self-propagating high-temperature synthesis (SHS) using reactants of fly ash-based silica, sawdust-based activated carbon, and magnesium. Fly ash-based silica and sawdust-based activated carbon were prepared from coal mining fly ash and Para rubber-wood sawdust, respectively. The work investigated the effects of the synthesis atmosphere (air and Ar) on the phase and morphology of the SHS products. The SHS product was leached by a two-step acid leaching processes, to obtain the Si-SiC composite powder. The SHS product and SHS product after leaching were characterized by X-ray diffractometry, scanning electron microscopy and energy dispersive X-ray spectrometry. The results indicated that the SHS product synthesized in air consisted of Si, SiC, MgO, and intermediate phases (SiO2, Mg, Mg2SiO4, Mg2Si), whereas the SHS product synthesized in Ar consisted of Si, SiC, MgO and a little Mg2SiO4. The SiC content in the leached-SHS product was higher when Ar was used as the synthesis atmosphere. As well as affecting the purity, the synthesis atmospheres also affected the average crystalline sizes of the products. The crystalline size of the product synthesized in Ar was smaller than that of the product synthesized in air. All of the results showed that fly ash and sawdust could be effective waste-material reactants for the synthesis of Si-SiC composite powders.

  20. Low-temperature Au/a-Si wafer bonding

    International Nuclear Information System (INIS)

    Jing, Errong; Xiong, Bin; Wang, Yuelin

    2011-01-01

    The Si/SiO 2 /Ti/Au–Au/Ti/a-Si/SiO 2 /Si bonding structure, which can also be used for the bonding of non-silicon material, was investigated for the first time in this paper. The bond quality test showed that the bond yield, bond repeatability and average shear strength are higher for this bonding structure. The interfacial microstructure analysis indicated that the Au-induced crystallization of the amorphous silicon process leads to big Si grains extending across the bond interface and Au filling the other regions of the bond interface, which result into a strong and void-free bond interface. In addition, the Au-induced crystallization reaction leads to a change in the IR images of the bond interface. Therefore, the IR microscope can be used to evaluate and compare the different bond strengths qualitatively. Furthermore, in order to verify the superiority of the bonding structure, the Si/SiO 2 /Ti/Au–a-Si/SiO 2 /Si (i.e. no Ti/Au layer on the a-Si surface) and Si/SiO 2 /Ti/Au–Au/Ti/SiO 2 /Si bonding structures (i.e. Au thermocompression bonding) were also investigated. For the Si/SiO 2 /Ti/Au–a-Si/SiO 2 /Si bonding structure, the poor bond quality is due to the native oxide layer on the a-Si surface, and for the Si/SiO 2 /Ti/Au–Au/Ti/SiO 2 /Si bonding structure, the poor bond quality is caused by the wafer surface roughness which prevents intimate contact and limits the interdiffusion at the bond interface.

  1. Impact of environmental pollution on the incidence of malignant neoplasms of upper respiratory tract in the population of Mysłowice, Imielin and Chełm Śląski

    Directory of Open Access Journals (Sweden)

    Jerzy Stockfisch

    2014-03-01

    Full Text Available Background. The paper presents a retrospective analysis of cases of the upper respiratory tract malignant tumors in the settlement: Mysłowice, Imielin, Chełm Śląski based on the patients’ medical history treated in a hospital laryngological ward in Mysłowice between 1995 and 2004. The inspiration to write the paper was the significant frequency of the upper respiratory tract malignant tumor cases in the main areas of Mysłowice; Piasek and Rymera estate. The aim of the study was the assessment of relationship between environmental pollution and territorial diversity in the morbidity of head and neck cancer. Material and methods. The study involved a group of 130 patients with cancer of the upper respiratory tract and a control group of 145 healthy subjects of similar age and sex, living in the different regions of the surveyed towns in the comparable proportions and in the group of patients. The paper aimed to assess the relationship between territorial diversity of the upper respiratory tract cancers, and environmental risk factors. Results. The analysis was based on environmental pollution data. It was confirmed that the geographic picture of the incidence of the upper airways malignant tumors showed that Mysłowice central districts: Piasek and estate Rymera, indicated this region to be particularly critical one. Conclusions. The increased number of morbidity cases in these districts may be associated with: environmental risk factors, increased consumption of high percentage alcohol, excessive amount of smoked cigarette and low socio-economic status of the patients.

  2. Gas-source molecular beam epitaxy of Si(111) on Si(110) substrates by insertion of 3C-SiC(111) interlayer for hybrid orientation technology

    Energy Technology Data Exchange (ETDEWEB)

    Bantaculo, Rolando, E-mail: rolandobantaculo@yahoo.com; Saitoh, Eiji; Miyamoto, Yu; Handa, Hiroyuki; Suemitsu, Maki

    2011-11-01

    A method to realize a novel hybrid orientations of Si surfaces, Si(111) on Si(110), has been developed by use of a Si(111)/3C-SiC(111)/Si(110) trilayer structure. This technology allows us to use the Si(111) portion for the n-type and the Si(110) portion for the p-type channels, providing a solution to the current drive imbalance between the two channels confronted in Si(100)-based complementary metal oxide semiconductor (CMOS) technology. The central idea is to use a rotated heteroepitaxy of 3C-SiC(111) on Si(110) substrate, which occurs when a 3C-SiC film is grown under certain growth conditions. Monomethylsilane (SiH{sub 3}-CH{sub 3}) gas-source molecular beam epitaxy (GSMBE) is used for this 3C-SiC interlayer formation while disilane (Si{sub 2}H{sub 6}) is used for the top Si(111) layer formation. Though the film quality of the Si epilayer leaves a lot of room for betterment, the present results may suffice to prove its potential as a new technology to be used in the next generation CMOS devices.

  3. Centrifugally cast Zn-27Al-xMg-ySi alloys and their in situ (Mg2Si + Si)/ZA27 composites

    International Nuclear Information System (INIS)

    Wang Qudong; Chen Yongjun; Chen Wenzhou; Wei Yinhong; Zhai Chunquan; Ding Wenjiang

    2005-01-01

    Effects of composition, mold temperature, rotating rate and modification on microstructure of centrifugally cast Zn-27Al-xMg-ySi alloys have been investigated. In situ composites of Zn-27Al-6.3Mg-3.7Si and Zn-27Al-9.8Mg-5.2Si alloys were fabricated by centrifugal casting using heated permanent mold. These composites consist of three layers: inner layer segregates lots of blocky primary Mg 2 Si and a litter blocky primary Si, middle layer contains without primary Mg 2 Si and primary Si, outer layer contains primary Mg 2 Si and primary Si. The position, quantity and distribution of primary Mg 2 Si and primary Si in the composites are determined jointly by alloy composition, solidification velocity under the effect of centrifugal force and their floating velocity inward. Na salt modifier can refine grain and primary Mg 2 Si and make primary Mg 2 Si distribute more evenly and make primary Si nodular. For centrifugally cast Zn-27Al-3.2Mg-1.8Si alloy, the microstructures of inner layer, middle layer and outer layer are almost similar, single layer materials without primary Mg 2 Si and primary Si are obtained, and their grain sizes increased with the mold temperature increasing

  4. Diffusion in ordered Fe-Si alloys

    International Nuclear Information System (INIS)

    Sepiol, B.; Vogl, G.

    1995-01-01

    The measurement of the diffusional Moessbauer line broadening in single crystalline samples at high temperatures provides microscopic information about atomic jumps. We can separate jumps of iron atoms between the various sublattices of Fe-Si intermetallic alloys (D0 3 structure) and measure their frequencies. The diffusion of iron in Fe-Si samples with Fe concentrations between 75 and 82 at% shows a drastic composition dependence: the jump frequency and the proportion between jumps on Fe sublattices and into antistructure (Si) sublattice positions change greatly. Close to Fe 3 Si stoichiometry iron diffusion is extremely fast and jumps are performed exclusively between the three Fe sublattices. The change in the diffusion process when changing the alloy composition from stoichiometric Fe 3 Si to the iron-rich side is discussed. (orig.)

  5. DLC-Si protective coatings for polycarbonates

    Directory of Open Access Journals (Sweden)

    Damasceno J.C.

    2003-01-01

    Full Text Available In this work, a-C:H:Si (DLC-Si films were produced onto crystalline silicon and polycarbonate substrates by the rf-PACVD technique from gaseous mixtures of CH4 + SiH4 and C2H2 + SiH4. The effects of self-bias and gas composition upon mechanical and optical properties of the films were investigated. Micro-hardness, residual stress, surface roughness and refractive index measurements were employed for characterization. By incorporating low concentrations of silicon and by exploring the more favorable conditions for the rf-PACVD deposition technique, highly adherent DLC-Si thin films were produced with reduced internal stresses (lower than 1 GPa, high hardness (around 20 GPa and high deposition rates (up to 10 µm/h. Results that show the technological viability of this material for application as protective coatings for polycarbonates are also discussed.

  6. SiC for microwave power transistors

    Energy Technology Data Exchange (ETDEWEB)

    Sriram, S.; Siergiej, R.R.; Clarke, R.C.; Agarwal, A.K.; Brandt, C.D. [Northrop Grumman Sci. and Technol. Center, Pittsburgh, PA (United States)

    1997-07-16

    The advantages of SiC for high power, microwave devices are discussed. The design considerations, fabrication, and experimental results are described for SiC MESFETs and SITs. The highest reported f{sub max} for a 0.5 {mu}m MESFET using semi-insulating 4H-SiC is 42 GHz. These devices also showed a small signal gain of 5.1 dB at 20 GHz. Other 4H-SiC MESFETs have shown a power density of 3.3 W/mm at 850 MHz. The largest SiC power transistor reported is a 450 W SIT measured at 600 MHz. The power output density of this SIT is 2.5 times higher than that of comparable silicon devices. SITs have been designed to operate as high as 3.0 GHz, with a 3 cm periphery part delivering 38 W of output power. (orig.) 28 refs.

  7. Pseudomorphic GeSiSn, SiSn and Ge layers in strained heterostructures

    Science.gov (United States)

    Timofeev, V. A.; Nikiforov, A. I.; Tuktamyshev, A. R.; Mashanov, V. I.; Loshkarev, I. D.; Bloshkin, A. A.; Gutakovskii, A. K.

    2018-04-01

    The GeSiSn, SiSn layer growth mechanisms on Si(100) were investigated and the kinetic diagrams of the morphological GeSiSn, SiSn film states in the temperature range of 150 °C-450 °C at the tin content from 0% to 35% were built. The phase diagram of the superstructural change on the surface of Sn grown on Si(100) in the annealing temperature range of 0 °C-850 °C was established. The specular beam oscillations were first obtained during the SiSn film growth from 150 °C to 300 °C at the Sn content up to 35%. The transmission electron microscopy and x-ray diffractometry data confirm the crystal perfection and the pseudomorphic GeSiSn, SiSn film state, and also the presence of smooth heterointerfaces between GeSiSn or SiSn and Si. The photoluminescence for the multilayer periodic GeSiSn/Si structures in the range of 0.6-0.8 eV was detected. The blue shift with the excitation power increase is observed suggesting the presence of a type II heterostructure. The creation of tensile strained Ge films, which are pseudomorphic to the underlying GeSn layer, is confirmed by the results of the formation and analysis of the reciprocal space map in the x-ray diffractometry. The tensile strain in the Ge films reached the value in the range of 0.86%-1.5%. The GeSn buffer layer growth in the Sn content range from 8% to 12% was studied. The band structure of heterosystems based on pseudomorphic GeSiSn, SiSn and Ge layers was calculated and the valence and conduction band subband position dependences on the Sn content were built. Based on the calculation, the Sn content range in the GeSiSn, SiSn, and GeSn layers, which corresponds to the direct bandgap GeSiSn, SiSn, and Ge material, was obtained.

  8. Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

    DEFF Research Database (Denmark)

    Pankratov, V.; Osinniy, Viktor; Kotlov, A.

    2011-01-01

    done. It is demonstrated that the experimentally determined blueshift of the photoluminescence excitation and absorption spectra is larger than the theoretical predictions. The influence of point defects in the SiO2 matrix on the optical and luminescence properties of the embedded Si nanocrystals...... is discussed. Moreover, it is demonstrated that no energy transfer takes place between the SiO2 and Si nanocrystals when the excitation energy is higher than the band-to-band transition energy in SiO2....

  9. Luminescence of solar cells with a-Si:H/c-Si heterojunctions

    Science.gov (United States)

    Zhigunov, D. M.; Il'in, A. S.; Forsh, P. A.; Bobyl', A. V.; Verbitskii, V. N.; Terukov, E. I.; Kashkarov, P. K.

    2017-05-01

    We have studied the electroluminescence (EL) and photoluminescence (PL) of solar cells containing a-Si:H/c-Si heterojunctions. It is established that both the EL and PL properties of these cells are determined by the radiative recombination of nonequilibrium carriers in crystalline silicon (c-Si). The external EL energy yield (efficiency) of solar cells with a-Si:H/c-Si heterojunctions at room temperature amounts to 2.1% and exceeds the value reached in silicon diode structures. This large EL efficiency can be explained by good passivation of the surface of crystalline silicon and the corresponding increase in lifetime of minority carrier s in these solar cells.

  10. Positron annihilation in SiO 2-Si studied by a pulsed slow positron beam

    Science.gov (United States)

    Suzuki, R.; Ohdaira, T.; Uedono, A.; Kobayashi, Y.

    2002-06-01

    Positron and positronium (Ps) behavior in SiO 2-Si have been studied by means of positron annihilation lifetime spectroscopy (PALS) and age-momentum correlation (AMOC) spectroscopy with a pulsed slow positron beam. The PALS study of SiO 2-Si samples, which were prepared by a dry-oxygen thermal process, revealed that the positrons implanted in the Si substrate and diffused back to the interface do not contribute to the ortho-Ps long-lived component, and the lifetime spectrum of the interface has at least two components. From the AMOC study, the momentum distribution of the ortho-Ps pick-off annihilation in SiO 2, which shows broader momentum distribution than that of crystalline Si, was found to be almost the same as that of free positron annihilation in SiO 2. A varied interface model was proposed to interpret the results of the metal-oxide-semiconductor (MOS) experiments. The narrow momentum distribution found in the n-type MOS with a negative gate bias voltage could be attributed to Ps formation and rapid spin exchange in the SiO 2-Si interface. We have developed a two-dimensional positron lifetime technique, which measures annihilation time and pulse height of the scintillation gamma-ray detector for each event. Using this technique, the positronium behavior in a porous SiO 2 film, grown by a sputtering method, has been studied.

  11. Improving Passivation Process of Si Nanocrystals Embedded in SiO2 Using Metal Ion Implantation

    Directory of Open Access Journals (Sweden)

    Jhovani Bornacelli

    2013-01-01

    Full Text Available We studied the photoluminescence (PL of Si nanocrystals (Si-NCs embedded in SiO2 obtained by ion implantation at MeV energy. The Si-NCs are formed at high depth (1-2 μm inside the SiO2 achieving a robust and better protected system. After metal ion implantation (Ag or Au, and a subsequent thermal annealing at 600°C under hydrogen-containing atmosphere, the PL signal exhibits a noticeable increase. The ion metal implantation was done at energies such that its distribution inside the silica does not overlap with the previously implanted Si ion . Under proper annealing Ag or Au nanoparticles (NPs could be nucleated, and the PL signal from Si-NCs could increase due to plasmonic interactions. However, the ion-metal-implantation-induced damage can enhance the amount of hydrogen, or nitrogen, that diffuses into the SiO2 matrix. As a result, the surface defects on Si-NCs can be better passivated, and consequently, the PL of the system is intensified. We have selected different atmospheres (air, H2/N2 and Ar to study the relevance of these annealing gases on the final PL from Si-NCs after metal ion implantation. Studies of PL and time-resolved PL indicate that passivation process of surface defects on Si-NCs is more effective when it is assisted by ion metal implantation.

  12. First-principles calculations of orientation dependence of Si thermal oxidation based on Si emission model

    Science.gov (United States)

    Nagura, Takuya; Kawachi, Shingo; Chokawa, Kenta; Shirakawa, Hiroki; Araidai, Masaaki; Kageshima, Hiroyuki; Endoh, Tetsuo; Shiraishi, Kenji

    2018-04-01

    It is expected that the off-state leakage current of MOSFETs can be reduced by employing vertical body channel MOSFETs (V-MOSFETs). However, in fabricating these devices, the structure of the Si pillars sometimes cannot be maintained during oxidation, since Si atoms sometimes disappear from the Si/oxide interface (Si missing). Thus, in this study, we used first-principles calculations based on the density functional theory, and investigated the Si emission behavior at the various interfaces on the basis of the Si emission model including its atomistic structure and dependence on Si crystal orientation. The results show that the order in which Si atoms are more likely to be emitted during thermal oxidation is (111) > (110) > (310) > (100). Moreover, the emission of Si atoms is enhanced as the compressive strain increases. Therefore, the emission of Si atoms occurs more easily in V-MOSFETs than in planar MOSFETs. To reduce Si missing in V-MOSFETs, oxidation processes that induce less strain, such as wet or pyrogenic oxidation, are necessary.

  13. EFFECT OF THE Si POWDER ADDITIONS ON THE PROPERTIES OF SiC COMPOSITES

    Directory of Open Access Journals (Sweden)

    GUOGANG XU

    2012-09-01

    Full Text Available By means of transient plastic phase process, the SiC silicon carbide kiln furniture materials were produced through adding Si powder to SiC materials. At the condition of the same additions of SiO2 powder, the effect of the Si powder additions on properties of silicon carbide materials after sintered at 1450°C for 3 h in air atmosphere was studied by means of SEM and other analysis methods. The results showed that silicon powder contributes to both sintering by liquid state and plastic phase combination to improve the strength of samples. When the Si powder additions is lower than 3.5 %, the density and strength of samples increase and porosity decrease with increasing Si powder additions. However when the Si powder additions is higher than 3.5 %, the density and strength of samples decrease and porosity increase with increasing Si powder additions. With increasing of Si additions, the residual strength of sample after thermal shocked increased and linear change rate decreased, and get to boundary value when Si additions is 4.5 %. The results also indicated that at the same sintering temperature, the sample with 3.5 % silicon powder has maximum strength.

  14. Uniform Si nano-dot fabrication using reconstructed structure of Si(110)

    Science.gov (United States)

    Yano, Masahiro; Uozumi, Yuki; Yasuda, Satoshi; Asaoka, Hidehito

    2018-06-01

    Si nano-dot (ND) formation on Si(110) is observed by means of a scanning tunneling microscope (STM). The initial Si-NDs are Si crystals that are continuous from the substrate and grow during the oxide layer desorption. The NDs fabricated on the flat surface of Si(110)-1 × 1 are surrounded by four types of facets with almost identical appearance probabilities. An increase in the size of the NDs increases the variety of its morphology. In contrast, most Si-NDs fabricated on straight-stepped surface of Si(110)-16 × 2 reconstructed structure are surrounded by only a single type of facet, namely the \\text{Si}(17,15,1)-2 × 1 plane. An appearance probability of the facet in which the base line is along the step of Si(110)-16 × 2 exceeds 75%. This finding provides a fabrication technique of uniformed structural Si-NDs by using the reconstructed structure of Si(110).

  15. Preparation and Characterization of SiO2/SiCN Core-shell Ceramic Microspheres

    Directory of Open Access Journals (Sweden)

    ZHANG Hai-yuan

    2017-05-01

    Full Text Available The SiO2/PSN core-shell microspheres were prepared via an emulsion reaction combined with the polymer-derived ceramics (PDCs method using polysilazane (PSN in situ polymerization on the surface of SiO2 modified by silane coupling agents MPS, followed by pyrolysis process to obtain SiO2/SiCN core-shell ceramic microspheres. The effects of raw mass ratio, curing time and pyrolysis temperature on the formation and the morphology of core-shell microspheres were studied. The morphology, chemical composition and phase transformation were characterized by SEM, EDS, TEM, FT-IR and XRD. The results show that after reaction for 4h at 200℃, SiO2 completely coated PSN forms a core-shell microsphere with rough surface when the mass ratio of SiO2 and PSN is 1:4; when pyrolysis temperature is at 800-1200℃, amorphous SiO2/SiCN core-shell ceramic microspheres are prepared; at 1400℃, the amorphous phase partially crystallizes to produce SiO2, SiC and Si3N4 phase.

  16. Neutron tolerance of advanced SiC-fiber/CVI-SiC composites

    International Nuclear Information System (INIS)

    Katoh, Y.; Kohyama, A.; Snead, L.L.; Hinoki, T.; Hasegawa, A.

    2003-01-01

    Fusion blankets employing a silicon carbide (SiC) fiber-reinforced SiC matrix composite (SiC/SiC composite) as the structural material provide attractive features represented by high cycle efficiency and extremely low induced radioactivity. Recent advancement in processing and utilization techniques and application studies in ceramic gas turbine and advanced transportation systems, SiC/SiC composites are steadily getting matured as industrial materials. Reference SiC/SiC composites for fusion structural applications have been produced by a forced-flow chemical vapor infiltration (FCVI) method using conventional and advanced near-stoichiometric SiC fibers and extensively evaluated primarily in Japan-US collaborative JUPITER program. In this work, effect of neutron irradiation at elevated temperatures on mechanical property of these composites is characterized. Unlike in conventional SiC/SiC composites, practically no property degradation was identified in advanced composites with a thin carbon interphase by a neutron fluence level of approximately 8dpa at 800C. (author)

  17. Time-resolved photoluminescence of SiOx encapsulated Si

    Science.gov (United States)

    Kalem, Seref; Hannas, Amal; Österman, Tomas; Sundström, Villy

    Silicon and its oxide SiOx offer a number of exciting electrical and optical properties originating from defects and size reduction enabling engineering new electronic devices including resistive switching memories. Here we present the results of photoluminescence dynamics relevant to defects and quantum confinement effects. Time-resolved luminescence at room temperature exhibits an ultrafast decay component of less than 10 ps at around 480 nm and a slower component of around 60 ps as measured by streak camera. Red shift at the initial stages of the blue luminescence decay confirms the presence of a charge transfer to long lived states. Time-correlated single photon counting measurements revealed a life-time of about 5 ns for these states. The same quantum structures emit in near infrared close to optical communication wavelengths. Nature of the emission is described and modeling is provided for the luminescence dynamics. The electrical characteristics of metal-oxide-semiconductor devices were correlated with the optical and vibrational measurement results in order to have better insight into the switching mechanisms in such resistive devices as possible next generation RAM memory elements. ``This work was supported by ENIAC Joint Undertaking and Laser-Lab Europe''.

  18. Effects of SiC amount on phase compositions and properties of Ti3SiC2-based composites

    Institute of Scientific and Technical Information of China (English)

    蔡艳芝; 殷小玮; 尹洪峰

    2015-01-01

    The phase compositions and properties of Ti3SiC2-based composites with SiC addition of 5%−30% in mass fraction fabricated by in-situ reaction and hot pressing sintering were studied. SiC addition effectively prevented TiC synthesis but facilitated SiC synthesis. The Ti3SiC2/TiC−SiC composite had better oxidation resistance when SiC added quantity reached 20% but poorer oxidation resistance with SiC addition under 15%than Ti3SiC2/TiC composite at higher temperatures. There were more than half of the original SiC and a few Ti3SiC2 remaining in Ti3SiC2/TiC−SiC with 20% SiC addition, but all constituents in Ti3Si2/TiC composite were oxidized after 12 h in air at 1500 °C. The oxidation scale thickness of TS30, 1505.78μm, was near a half of that of T, 2715μm, at 1500 °C for 20 h. Ti3SiC2/TiC composite had a flexural strength of 474 MPa, which was surpassed by Ti3SiC2/TiC−SiC composites when SiC added amount reached 15%. The strength reached the peak of 518 MPa at 20%SiC added amount.

  19. Investigation on fabrication of SiC/SiC composite as a candidate material for fuel sub-assembly

    International Nuclear Information System (INIS)

    Lee, Jae-Kwang; Naganuma, Masayuki; Park, Joon-Soo; Kohyama, Akira

    2005-01-01

    The possibility of SiC/SiC (Silicon carbide fiber reinforced Silicon carbide) composites application for fuel sub-assembly of Fast Breeder Reactor was investigated. To select a raw material of SiC/SiC composites, a few kinds of SiC nano powder was estimated by SEM observation and XRD analysis. Furthermore, SiC monolithic was sintered from them and estimated by flexural test. SiC nano-powder which showed good sinterability, it was used for fabrication of SiC/SiC composites by Hot Pressing method. From the sintering condition of 1800, 1820degC temperature and 15, 20 MPa pressure, SiC/SiC composite was fabricated and then estimated by tensile test. SiC/SiC composite, which made by 1820degC and 20 MPa condition, showed the highest mechanical strength by the monotonic tensile test. SiC/SiC composite, which made by 1800degC and 15 MPa condition, showed a stable fracture behavior at the monotonic and cyclic tensile test. And then, the hoop stress of ideal model of SiC/SiC composites was discussed. It was confirmed that applicability of SiC/SiC composites by Hot Pressing method for fuel sub-assembly structural material. To make it real attractive one, to maintain the reliability and safety as a high temperature structural material, the design and process study on SiC/Sic composites material will be continued. (author)

  20. Positron annihilation spectroscopy of the interface between nanocrystalline Si and SiO2

    International Nuclear Information System (INIS)

    Pi, X.D.; Coleman, P.G.; Harding, R.; Davies, G.; Gwilliam, R.M.; Sealy, B.J.

    2003-01-01

    Positron annihilation spectroscopy has been employed to study changes in the interface region between nanocrystalline Si and SiO 2 , following annealing between 400 deg. C and 900 deg. C in nitrogen or oxygen. With the support of photoluminescence spectroscopy we find that nitrogen and oxygen are trapped in voids at the interface at low temperatures. At temperatures above 700 deg. C both nitrogen and oxygen react with Si nanocrystals, and the resulting volume increase introduces stress in the SiO 2 matrix which is relaxed by the shrinkage of its intrinsic open volume. Oxygen appears to enhance Si diffusion in SiO 2 so that the agglomeration of Si nanocrystals occurs more readily during annealing in oxygen than in nitrogen

  1. Thickness dependent formation and properties of GdSi2/Si(100) interfaces

    International Nuclear Information System (INIS)

    Peto, G.; Molnar, G.; Dozsa, L.; Horvath, Z.E.; Horvath, Zs.J.; Zsoldos, E.; Dimitriadis, C.A.; Papadimitriou, L.

    2005-01-01

    Epitaxial and polycrystalline orthorhombic GdSi 2 films were grown on Si(100) substrates by solid phase reaction between Si and Gd films at different thicknesses of the Gd film. The most important property of these GdSi 2 /Si interfaces was defect formation. This was investigated by studying the properties of the Schottky barriers by means of current voltage and capacitance-voltage characteristics, deep level transient spectroscopy by double crystal X-ray diffractometry, and transmission electron microscopy. Epitaxial growth of the silicide layer ensured a relatively low interface defect density (about 10 10 cm -2 ), while the non-epitaxial growth induced defects of a much higher density (about 10 12 cm -2 ). The defects generated during the silicide formation are located within a depth of about 10 nm from the GdSi 2 /Si interface. (orig.)

  2. Structural and electrical evaluation for strained Si/SiGe on insulator

    International Nuclear Information System (INIS)

    Wang Dong; Ii, Seiichiro; Ikeda, Ken-ichi; Nakashima, Hideharu; Ninomiya, Masaharu; Nakamae, Masahiko; Nakashima, Hiroshi

    2006-01-01

    Three strained Si/SiGe on insulator wafers having different Ge fractions were evaluated using dual-metal-oxide-semiconductor (dual-MOS) deep level transient spectroscopy (DLTS) and transmission electron microscopy (TEM) methods. The interface of SiGe/buried oxide (BOX) shows roughness less than 1 nm by high resolution TEM observation. The interface states densities (D it ) of SiGe/BOX are approximately 1 x 10 12 cm -2 eV -1 , which is approximately one order of magnitude higher than that of Si/BOX in a Si on insulator wafer measured as reference by the same method of dual-MOS DLTS. The high D it of SiGe/BOX is not due to interface roughness but due to Ge atoms. The threading dislocations were also clearly observed by TEM and were analyzed

  3. Ge nanocrystals embedded in ultrathin Si3N4 multilayers with SiO2 barriers

    Science.gov (United States)

    Bahariqushchi, R.; Gundogdu, Sinan; Aydinli, A.

    2017-04-01

    Multilayers of germanium nanocrystals (NCs) embedded in thin films of silicon nitride matrix separated with SiO2 barriers have been fabricated using plasma enhanced chemical vapor deposition (PECVD). SiGeN/SiO2 alternating bilayers have been grown on quartz and Si substrates followed by post annealing in Ar ambient from 600 to 900 °C. High resolution transmission electron microscopy (HRTEM) as well as Raman spectroscopy show good crystallinity of Ge confined to SiGeN layers in samples annealed at 900 °C. Strong compressive stress for SiGeN/SiO2 structures were observed through Raman spectroscopy. Size, as well as NC-NC distance were controlled along the growth direction for multilayer samples by varying the thickness of bilayers. Visible photoluminescence (PL) at 2.3 and 3.1 eV with NC size dependent intensity is observed and possible origin of PL is discussed.

  4. Silicon Effects on Properties of Melt Infiltrated SiC/SiC Composites

    Science.gov (United States)

    Bhatt, Ramakrishna T.; Gyekenyesi, John Z.; Hurst, Janet B.

    2000-01-01

    Silicon effects on tensile and creep properties, and thermal conductivity of Hi-Nicalon SiC/SiC composites have been investigated. The composites consist of 8 layers of 5HS 2-D woven preforms of BN/SiC coated Hi-Nicalon fiber mats and a silicon matrix, or a mixture of silicon matrix and SiC particles. The Hi-Nicalon SiC/silicon and Hi-Nicalon SiC/SiC composites contained about 24 and 13 vol% silicon, respectively. Results indicate residual silicon up to 24 vol% has no significant effect on creep and thermal conductivity, but does decrease the primary elastic modulus and stress corresponding to deviation from linear stress-strain behavior.

  5. Structural and photoluminescence properties of Si-based nanosheet bundles rooted on Si substrates

    Science.gov (United States)

    Yuan, Peiling; Tamaki, Ryo; Kusazaki, Shinya; Atsumi, Nanae; Saito, Yuya; Kumazawa, Yuki; Ahsan, Nazmul; Okada, Yoshitaka; Ishida, Akihiro; Tatsuoka, Hirokazu

    2018-04-01

    Si-based nanosheet bundles were synthesized by the extraction of Ca atoms from CaSi2 microwalls grown on Si substrates by inositol hexakisphosphate solution or thermal treatment in FeCl2 vapor. The structural and photoluminescence properties of the Si-based nanosheet bundles were examined. The photoluminescence emissions in the visible region were clearly observed, and the temperature and excitation intensity dependences of the emissions were characterized. The observed Si-based nanosheets consist of thin Si layers, and a superlattice-like layered structural model is proposed to describe the Si-based nanosheet bundle structures and their photoluminescence property. The photoluminescence property of the nanosheets significantly depends on their treatment process. The luminescence mechanism of the nanosheets was discussed.

  6. Light emissions from LiNbO sub 3 /SiO sub 2 /Si structures

    CERN Document Server

    Wu, X L; Tang, N; Deng, S S; Bao, X M

    2003-01-01

    LiNbO sub 3 (LN) films with a high degree of (006) texture were deposited on Si-based dense SiO sub 2 layers by pulsed laser deposition. After annealing, the LN/SiO sub 2 /Si structures were revealed to have ultraviolet-, green-, and red-emitting properties related to self-trapped excitons and E' defect pairs in the SiO sub 2 surface, which are induced by the photorefractive effect of the LN films. The emission wavelength can be tuned by introducing different dopants into the LN films. Waveguiding properties of the structures were demonstrated. The results obtained indicate that the LN/SiO sub 2 /Si structures could be expected to have important applications in modern optoelectronic integration. (letter to the editor)

  7. Solid-state 27Al and 29Si NMR investigations on Si-substituted hydrogarnets

    International Nuclear Information System (INIS)

    Rivas Mercury, J.M.; Pena, P.; Aza, A.H. de; Turrillas, X.; Sobrados, I.; Sanz, J.

    2007-01-01

    Partially deuterated Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x hydrates prepared by a reaction in the presence of D 2 O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by 29 Si and 27 Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The 29 Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca 3 Al 2 (SiO 4 ) 3-x (OH) 4x was followed by 27 Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH) 6 and Al(OSi)(OH) 5 environments. The NMR data obtained were consistent with the concentrations of the Al and Si species deduced from transmission electron microscopy energy-dispersive spectrometry and Rietveld analysis of both X-ray and neutron diffraction data

  8. La nuova fisica che ci aspetta

    CERN Multimedia

    Shiga, David

    2007-01-01

    The big accelerator that will enter in function at CERN at the end of the year will have the hard task to verify the relevance of the string theory, today the better candiddate to be the famous "theory of everything" that physicists are looking for since decades. (1 page)

  9. Using Screencasts in ChE Courses

    Science.gov (United States)

    Falconer, John L.; deGrazia, Janet; Medlin, J. Will; Holmberg, Michael P.

    2009-01-01

    Screencasts are digital recordings of the output from a computer monitor, including narration. Their use was piloted in five chemical engineering courses and the feedback from students was overwhelmingly positive. The screencasts were produced on Tablet PCs using Camtasia Studio software and were posted to the Blackboard classroom management…

  10. Isotopic effects in sub-barrier fusion of Si + Si systems

    Science.gov (United States)

    Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Esbensen, H.; Bourgin, D.; Čolović, P.; Corradi, L.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Szilner, S.; Urbani, M.; Zhang, G. L.

    2018-04-01

    Background: Recent measurements of fusion cross sections for the 28Si+28Si system revealed a rather unsystematic behavior; i.e., they drop faster near the barrier than at lower energies. This was tentatively attributed to the large oblate deformation of 28Si because coupled-channels (CC) calculations largely underestimate the 28Si+28Si cross sections at low energies, unless a weak imaginary potential is applied, probably simulating the deformation. 30Si has no permanent deformation and its low-energy excitations are of a vibrational nature. Previous measurements of this system reached only 4 mb, which is not sufficient to obtain information on effects that should show up at lower energies. Purpose: The aim of the present experiment was twofold: (i) to clarify the underlying fusion dynamics by measuring the symmetric case 30Si+30Si in an energy range from around the Coulomb barrier to deep sub-barrier energies, and (ii) to compare the results with the behavior of 28Si+28Si involving two deformed nuclei. Methods: 30Si beams from the XTU tandem accelerator of the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nucleare were used, bombarding thin metallic 30Si targets (50 μ g /cm2) enriched to 99.64 % in mass 30. An electrostatic beam deflector allowed the detection of fusion evaporation residues (ERs) at very forward angles, and angular distributions of ERs were measured. Results: The excitation function of 30Si+30Si was measured down to the level of a few microbarns. It has a regular shape, at variance with the unusual trend of 28Si+28Si . The extracted logarithmic derivative does not reach the LCS limit at low energies, so that no maximum of the S factor shows up. CC calculations were performed including the low-lying 2+ and 3- excitations. Conclusions: Using a Woods-Saxon potential the experimental cross sections at low energies are overpredicted, and this is a clear sign of hindrance, while the calculations performed with a M3Y + repulsion

  11. Mushroom-free selective epitaxial growth of Si, SiGe and SiGe:B raised sources and drains

    Science.gov (United States)

    Hartmann, J. M.; Benevent, V.; Barnes, J. P.; Veillerot, M.; Lafond, D.; Damlencourt, J. F.; Morvan, S.; Prévitali, B.; Andrieu, F.; Loubet, N.; Dutartre, D.

    2013-05-01

    We have evaluated various Cyclic Selective Epitaxial Growth/Etch (CSEGE) processes in order to grow "mushroom-free" Si and SiGe:B Raised Sources and Drains (RSDs) on each side of ultra-short gate length Extra-Thin Silicon-On-Insulator (ET-SOI) transistors. The 750 °C, 20 Torr Si CSEGE process we have developed (5 chlorinated growth steps with four HCl etch steps in-between) yielded excellent crystalline quality, typically 18 nm thick Si RSDs. Growth was conformal along the Si3N4 sidewall spacers, without any poly-Si mushrooms on top of unprotected gates. We have then evaluated on blanket 300 mm Si(001) wafers the feasibility of a 650 °C, 20 Torr SiGe:B CSEGE process (5 chlorinated growth steps with four HCl etch steps in-between, as for Si). As expected, the deposited thickness decreased as the total HCl etch time increased. This came hands in hands with unforeseen (i) decrease of the mean Ge concentration (from 30% down to 26%) and (ii) increase of the substitutional B concentration (from 2 × 1020 cm-3 up to 3 × 1020 cm-3). They were due to fluctuations of the Ge concentration and of the atomic B concentration [B] in such layers (drop of the Ge% and increase of [B] at etch step locations). Such blanket layers were a bit rougher than layers grown using a single epitaxy step, but nevertheless of excellent crystalline quality. Transposition of our CSEGE process on patterned ET-SOI wafers did not yield the expected results. HCl etch steps indeed helped in partly or totally removing the poly-SiGe:B mushrooms on top of the gates. This was however at the expense of the crystalline quality and 2D nature of the ˜45 nm thick Si0.7Ge0.3:B recessed sources and drains selectively grown on each side of the imperfectly protected poly-Si gates. The only solution we have so far identified that yields a lesser amount of mushrooms while preserving the quality of the S/D is to increase the HCl flow during growth steps.

  12. Luminescence properties of Si-capped β-FeSi{sub 2} nanodots epitaxially grown on Si(001) and (111) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Amari, Shogo; Ichikawa, Masakazu [Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nakamura, Yoshiaki, E-mail: nakamura@ee.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531 (Japan); PRESTO, JST, 4-1-8 Honcho Kawaguchi, Saitama 332-0012 (Japan)

    2014-02-28

    We studied the luminescence properties of Si-capped β-FeSi{sub 2} nanodots (NDs) epitaxially grown on Si substrates by using photoluminescence (PL) and electroluminescence (EL) spectroscopies. Codepositing Fe and Si on ultrathin SiO{sub 2} films induced the self-assembly of epitaxial β-FeSi{sub 2} NDs. The PL spectra of the Si/β-FeSi{sub 2} NDs/Si structure depended on the crystal orientation of the Si substrate. These structures exhibited a broad PL peak near 0.8 eV on both Si(001) and (111) substrates. The PL intensity depended on the shape of the β-FeSi{sub 2} NDs. For the flat NDs, which exhibited higher PL intensity, we also recorded EL spectra. We explained the luminescence properties of these structures by the presence of nanostructured Si offering radiative electronic states in the Si cap layers, generated by nano-stressors for upper Si layer: the strain-relaxed β-FeSi{sub 2} NDs.

  13. Experimental and thermodynamic assessments of substitutions in the AlFeSi, FeMnSi, FeSiZr and AlCaFeSi systems (65 wt % Si) - solidification simulation

    International Nuclear Information System (INIS)

    Gueneau, C.; Ansara, I.

    1994-01-01

    The substitutions of Al Si, Fe Mn and Fe Zr in some intermetallic compounds of the Al-Fe-Si, Fe-Mn-Si and Fe-Si-Zr systems are modelled in the Si-rich corner using a two sublattice model. The solidification paths of the studied alloys are determined at equilibrium. The ascalculated phase volume fractions of the alloys are compared to the experimental ones. Finally, a solidification simulation using the Gulliver-Scheil's model is performed in order to explain the formation of some precipitates experimentally observed. (authors). 14 figs., 19 refs

  14. Influence of SiC coating thickness on mechanical properties of SiCf/SiC composite

    Science.gov (United States)

    Yu, Haijiao; Zhou, Xingui; Zhang, Wei; Peng, Huaxin; Zhang, Changrui

    2013-11-01

    Silicon carbide (SiC) coatings with varying thickness (ranging from 0.14 μm to 2.67 μm) were deposited onto the surfaces of Type KD-I SiC fibres with native carbonaceous surface using chemical vapour deposition (CVD) process. Then, two dimensional SiC fibre reinforced SiC matrix (2D SiCf/SiC) composites were fabricated using polymer infiltration and pyrolysis (PIP) process. Influences of the fibre coating thickness on mechanical properties of SiC fibre and SiCf/SiC composite were investigated using single-filament test and three-point bending test. The results indicated that flexural strength of the composites initially increased with the increasing CVD SiC coating thickness and reached a peak value of 363 MPa at the coating thickness of 0.34 μm. Further increase in the coating thickness led to a rapid decrease in the flexural strength of the composites. The bending modulus of composites showed a monotonic increase with increasing coating thickness. A chemical attack of hydrogen or other ions (e.g. a C-H group) on the surface of SiC fibres during the coating process, owing to the formation of volatile hydrogen, lead to an increment of the surface defects of the fibres. This was confirmed by Wang et al. [35] in their work on the SiC coating of the carbon fibre. In the present study, the existing ˜30 nm carbon on the surface of KD-I fibre [36] made the fibre easy to be attacked. Deposition of non-stoichiometric SiC, causing a decrease in strength. During the CVD process, a small amount of free silicon or carbon always existed [35]. The existence of free silicon, either disordered the structure of SiC and formed a new source of cracks or attacked the carbon on fibre surface resulting in properties degeneration of the KD-I fibre. The effect of residual stress. The different thermal expansion coefficient between KD-I SiC fibre and CVD SiC coating, which are 3 × 10-6 K-1 (RT ˜ 1000 °C) and 4.6 × 10-6 K-1 (RT ˜ 1000 °C), respectively, could cause residual stress

  15. Passivation of defect states in Si and Si/SiO2 interface states by cyanide treatment: improvement of characteristics of pin-junction amorphous Si and crystalline Si-based metal-oxide-semiconductor junction solar cells

    International Nuclear Information System (INIS)

    Fujiwara, N.; Fujinaga, T.; Niinobe, D.; Maida, O.; Takahashi, M.; Kobayashi, H.

    2003-01-01

    Defect states in Si can be passivated by cyanide treatment which simply involves immersion of Si materials in KCN solutions, followed by rinse. When the cyanide treatment is applied to pin-junction amorphous Si [a-Si] solar cells, the initial conversion efficiency increases. When the crown-ether cyanide treatment using a KCN solution of xylene containing 18-crown-6 is performed on i-a-Si films, decreases in the photo- and dark current densities with the irradiation time are prevented. The cyanide treatment can also passivate interface states present at Si/SiO 2 interfaces, leading to an increase in the conversion efficiency of 2 / Si (100)> solar cells.. Si-CN bonds formed by the reaction of defect states with cyanide ions have a high bond energy of about 4.5 eV and hence heat treatment at 800 0 C does not rupture the bonds, making thermal stability of the cyanide treatment.. When the cyanide treatment is applied to ultrathin SiO 2 /Si structure, the leakage current density is markedly decreased (Authors)

  16. Si Wire-Array Solar Cells

    Science.gov (United States)

    Boettcher, Shannon

    2010-03-01

    Micron-scale Si wire arrays are three-dimensional photovoltaic absorbers that enable orthogonalization of light absorption and carrier collection and hence allow for the utilization of relatively impure Si in efficient solar cell designs. The wire arrays are grown by a vapor-liquid-solid-catalyzed process on a crystalline (111) Si wafer lithographically patterned with an array of metal catalyst particles. Following growth, such arrays can be embedded in polymethyldisiloxane (PDMS) and then peeled from the template growth substrate. The result is an unusual photovoltaic material: a flexible, bendable, wafer-thickness crystalline Si absorber. In this paper I will describe: 1. the growth of high-quality Si wires with controllable doping and the evaluation of their photovoltaic energy-conversion performance using a test electrolyte that forms a rectifying conformal semiconductor-liquid contact 2. the observation of enhanced absorption in wire arrays exceeding the conventional light trapping limits for planar Si cells of equivalent material thickness and 3. single-wire and large-area solid-state Si wire-array solar cell results obtained to date with directions for future cell designs based on optical and device physics. In collaboration with Michael Kelzenberg, Morgan Putnam, Joshua Spurgeon, Daniel Turner-Evans, Emily Warren, Nathan Lewis, and Harry Atwater, California Institute of Technology.

  17. Joining SiC/SiC composites for fusion applications

    International Nuclear Information System (INIS)

    Henager, C.J.

    2007-01-01

    Full text of publication follows: The use of SiC-reinforced composites for fusion reactors or other nuclear applications will likely require some form of joining in order to form large structural or functional sections. Joints must be able to allow load transfer to the composite material so that the fiber reinforcements are able to carry their designed loads and the joint should not fail in a brittle manner. In addition, joints must be tolerant of radiation damage similar to the composite material to maintain the structural integrity of the joined section. Other requirements of interest are low activation joints and ease of joining application and processing, which are a difficult set of criteria to meet. Research at PNNL has been directed at high-strength joints using solid-state displacement reactions and pre-ceramic polymer joints that are easy to apply and that could be used in field repair situations. This research will report on the further development and testing of such joints using a double notch shear (DNS) specimen that is suitable for in-reactor testing. The results reveal that the solid-state joints are stronger than the polymer-based joints but require high-temperature, high-pressure processing. The polymer-based joints can be applied with reduced pressure and temperature processing compared to the solid-state joints. The polymer-based joints may have adequate strength for some applications where ease of application and in situ processing are required. Although irradiation testing is not reported in this study the use of the DNS specimen is discussed with regard to future neutron irradiations. (authors)

  18. Light trapping of crystalline Si solar cells by use of nanocrystalline Si layer plus pyramidal texture

    Energy Technology Data Exchange (ETDEWEB)

    Imamura, Kentaro; Nonaka, Takaaki; Onitsuka, Yuya; Irishika, Daichi; Kobayashi, Hikaru, E-mail: h.kobayashi@sanken.osaka-u.ac.jp

    2017-02-15

    Highlights: • Ultralow reflectivity Si wafers with light trapping effect can be obtained by forming a nanocrystalline Si layer on pyramidal textured Si surfaces. • Surface passivation using phosphosilicate glass improved minority carrier lifetime of the nanocrystalline Si layer/Si structure. • A high photocurrent density of 40.1 mA/cm{sup 2}, and a high conversion efficiency of 18.5% were achieved. - Abstract: The surface structure chemical transfer (SSCT) method has been applied to fabrication of single crystalline Si solar cells with 170 μm thickness. The SSCT method, which simply involves immersion of Si wafers in H{sub 2}O{sub 2} plus HF solutions and contact of Pt catalyst with Si taking only ∼30 s for 6 in. wafers, can decrease the reflectivity to less than 3% by the formation of a nanocrystalline Si layer. However, the reflectivity of the nanocrystalline Si layer/flat Si surface/rear Ag electrode structure in the wavelength region longer than 1000 nm is high because of insufficient absorption of incident light. The reflectivity in the long wavelength region is greatly decreased by the formation of the nanocrystalline Si layer on pyramidal textured Si surfaces due to an increase in the optical path length. Deposition of phosphosilicate glass (PSG) on the nanocrystalline Si layer for formation of pn-junction does not change the ultralow reflectivity because the surface region of the nanocrystalline Si layer possesses a refractive index of 1.4 which is nearly the same as that of PSG of 1.4–1.5. The PSG layer is found to passivate the nanocrystalline Si layer, which is evident from an increase in the minority carrier lifetime from 12 to 44 μs. Hydrogen treatment at 450 °C further increases the minority carrier lifetime approximately to a doubled value. The solar cells with the Si layer/pyramidal Si substrate/boron-diffused back surface field/Ag rear electrode> structure show a high conversion efficiency of 18

  19. Microstructural optimization of high temperature SiC/SiC composites by nite process

    International Nuclear Information System (INIS)

    Shimoda, K.; Park, J.S.; Hinoki, T.; Kohyama, A.

    2007-01-01

    Full text of publication follows: SiC/SiC composites are one of the promising structural materials for future fusion reactor because of the excellent potentiality in thermal and mechanical properties under very severe environment including high temperature and high energy neutron bombardment. For fusion-grade SiC/SiC composites, high-crystallinity and near-stoichiometric characteristic are required to keep excellent stability against neutron irradiation. The realization of the reactor will be strongly depend on optimization of SiC/SiC composites microstructure, particularly in regard to the materials and processes used for the fiber, interphase and matrix constituents. One of the important accomplishments is the new process, called nano-particle infiltration and transient eutectic phase (NITE) process developed in our group. The microstructure of NITE-SiC/SiC composites, such as fiber volume fraction, porosity and type of pores, can be controlled precisely by the selection of sintering temperature/applied stress history. The objective of this study is to investigate thermal stability and mechanical properties of NITE-SiC/SiC composites at high-temperature. Two kinds of highly-densified SiC/SiC composites with the difference of fiber volume fraction were prepared, and were subjected to exposure tests from 1000 deg. C to 1500 deg. C in an argon-oxygen gas mixture with an oxygen partial pressure of 0.1 Pa. The thermal stability of the composites was characterized through mass change and TEM/SEM observation. The in-situ tensile tests at 1300 deg. C and 1500 deg. C were carried out in the same atmosphere. Most of SiC/SiC composites, even for the advanced CVI-SiC/SiC composites with multi-layered SiC/C inter-phases, underwent reduction in the maximum strength by about 20% at 1300 deg. C. In particular, this reduction was attributed to a slight burnout of the carbon interphase due to oxygen impurities in test atmosphere. However, there was no significant degradation for

  20. Microstructural optimization of high temperature SiC/SiC composites by nite process

    Energy Technology Data Exchange (ETDEWEB)

    Shimoda, K. [Kyoto Univ., Graduate School of Energy Science (Japan); Park, J.S. [Kyoto Univ., Institute of Advanced Energy (Japan); Hinoki, T.; Kohyama, A. [Kyoto Univ., lnstitute of Advanced Energy, Gokasho, Uji (Japan)

    2007-07-01

    Full text of publication follows: SiC/SiC composites are one of the promising structural materials for future fusion reactor because of the excellent potentiality in thermal and mechanical properties under very severe environment including high temperature and high energy neutron bombardment. For fusion-grade SiC/SiC composites, high-crystallinity and near-stoichiometric characteristic are required to keep excellent stability against neutron irradiation. The realization of the reactor will be strongly depend on optimization of SiC/SiC composites microstructure, particularly in regard to the materials and processes used for the fiber, interphase and matrix constituents. One of the important accomplishments is the new process, called nano-particle infiltration and transient eutectic phase (NITE) process developed in our group. The microstructure of NITE-SiC/SiC composites, such as fiber volume fraction, porosity and type of pores, can be controlled precisely by the selection of sintering temperature/applied stress history. The objective of this study is to investigate thermal stability and mechanical properties of NITE-SiC/SiC composites at high-temperature. Two kinds of highly-densified SiC/SiC composites with the difference of fiber volume fraction were prepared, and were subjected to exposure tests from 1000 deg. C to 1500 deg. C in an argon-oxygen gas mixture with an oxygen partial pressure of 0.1 Pa. The thermal stability of the composites was characterized through mass change and TEM/SEM observation. The in-situ tensile tests at 1300 deg. C and 1500 deg. C were carried out in the same atmosphere. Most of SiC/SiC composites, even for the advanced CVI-SiC/SiC composites with multi-layered SiC/C inter-phases, underwent reduction in the maximum strength by about 20% at 1300 deg. C. In particular, this reduction was attributed to a slight burnout of the carbon interphase due to oxygen impurities in test atmosphere. However, there was no significant degradation for

  1. Fabrication of poly-crystalline Si-based Mie resonators via amorphous Si on SiO2 dewetting.

    Science.gov (United States)

    Naffouti, Meher; David, Thomas; Benkouider, Abdelmalek; Favre, Luc; Ronda, Antoine; Berbezier, Isabelle; Bidault, Sebastien; Bonod, Nicolas; Abbarchi, Marco

    2016-02-07

    We report the fabrication of Si-based dielectric Mie resonators via a low cost process based on solid-state dewetting of ultra-thin amorphous Si on SiO2. We investigate the dewetting dynamics of a few nanometer sized layers annealed at high temperature to form submicrometric Si-particles. Morphological and structural characterization reveal the polycrystalline nature of the semiconductor matrix as well as rather irregular morphologies of the dewetted islands. Optical dark field imaging and spectroscopy measurements of the single islands reveal pronounced resonant scattering at visible frequencies. The linewidth of the low-order modes can be ∼20 nm in full width at half maximum, leading to a quality factor Q exceeding 25. These values reach the state-of-the-art ones obtained for monocrystalline Mie resonators. The simplicity of the dewetting process and its cost-effectiveness opens the route to exploiting it over large scales for applications in silicon-based photonics.

  2. Characterization of SiCf/SiC and CNT/SiC composite materials produced by liquid phase sintering

    International Nuclear Information System (INIS)

    Lee, J.K.; Lee, S.P.; Cho, K.S.; Byun, J.H.; Bae, D.S.

    2011-01-01

    This paper dealt with the microstructure and mechanical properties of SiC based composites reinforced with different reinforcing materials. The composites were fabricated using reinforcing materials of carbon nanotubes (CNT) and Tyranno Lox-M SiC chopped fibers. The volume fraction of carbon nanotubes was also varied in this composite system. An Al 2 O 3 -Y 2 O 3 powder mixture was used as a sintering additive in the consolidation of the SiC matrix. The characterization of the composites was investigated by means of SEM and three point bending tests. These composites showed a dense morphology of the matrix region, by the creation of a secondary phase. The composites reinforced with SiC chopped fibers possessed a flexural strength of about 400 MPa at room temperature. The flexural strength of the carbon nanotubes composites had a tendency to decrease with increased volume fraction of the reinforcing material.

  3. SiC-SiC and C-SiC Honeycomb for Advanced Flight Structures, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed project builds upon the work done in Phase I with the development of a C-SiC CMC honeycomb material that was successfully tested for mechanical...

  4. Narrow photoluminescence peak from Ge(Si) islands embedded between tensile-strained Si layers

    Energy Technology Data Exchange (ETDEWEB)

    Shaleev, Mikhail; Novikov, Alexey; Baydakova, Nataliya; Yablonskiy, Artem; Drozdov, Yuriy; Lobanov, Dmitriy; Krasilnik, Zakhary [Institute for Physics of Microstructures, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod (Russian Federation); Kuznetsov, Oleg [Physical-Technical Research Institute, Nizhny Novgorod State University, pr. Gagarina 23, 603950 Nizhny Novgorod (Russian Federation)

    2011-03-15

    The influence of thickness of the strained Si layers, measurement temperature and optical pumping power on width of the photoluminescence line from Ge(Si) self-assembled nanoislands grown on relaxed SiGe/Si(001) buffer layers and embedded between tensile-stained Si layers was studied. This line appears due to the II-type optical transition between the holes localized in islands and the electrons confined in tensile-strained Si layers under and above the islands. The possibility of tuning the photoluminescence line width by changing the strained Si layer thicknesses under and above the islands is showed. The decrease of the photoluminescence line width from Ge(Si) islands down to values comparable with width of the PL line from InAs/GaAs quantum dots was achieved due to the quantum confinement of electrons in thin strained Si layers and taking into account of the higher diffusion-induced smearing of strained Si layer above the islands. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Control of the graphene growth rate on capped SiC surface under strong Si confinement

    International Nuclear Information System (INIS)

    Çelebi, C.; Yanık, C.; Demirkol, A.G.; Kaya, İsmet İ.

    2013-01-01

    Highlights: ► Graphene is grown on capped SiC surface with well defined cavity size. ► Graphene growth rate linearly increases with the cavity height. ► Graphene uniformity is reduced with thickness. - Abstract: The effect of the degree of Si confinement on the thickness and morphology of UHV grown epitaxial graphene on (0 0 0 −1) SiC is investigated by using atomic force microscopy and Raman spectroscopy measurements. Prior to the graphene growth process, the C-face surface of a SiC substrate is capped by another SiC comprising three cavities on its Si-rich surface with depths varying from 0.5 to 2 microns. The Si atoms, thermally decomposed from the sample surface during high temperature annealing of the SiC cap /SiC sample stack, are separately trapped inside these individual cavities at the sample/cap interface. Our analyses show that the growth rate linearly increases with the cavity height. It was also found that stronger Si confinement yields more uniform graphene layers.

  6. The Degradation Behavior of SiCf/SiO2 Composites in High-Temperature Environment

    Science.gov (United States)

    Yang, Xiang; Cao, Feng; Qing, Wang; Peng, Zhi-hang; Wang, Yi

    2018-04-01

    SiCf/SiO2 composites had been fabricated efficiently by Sol-Gel method. The oxidation behavior, thermal shock property and ablation behavior of SiCf/SiO2 composites was investigated. SiCf/SiO2 composites showed higher oxidation resistance in oxidation atmosphere, the flexural strength retention ratio was larger than 90.00%. After 1300 °C thermal shock, the mass retention ratio was 97.00%, and the flexural strength retention ratio was 92.60%, while after 1500 °C thermal shock, the mass retention ratio was 95.37%, and the flexural strength retention ratio was 83.34%. After 15 s ablation, the mass loss rate was 0.049 g/s and recession loss rate was 0.067 mm/s. The SiO2 matrix was melted in priority and becomes loosen and porous. With the ablation going on, the oxides were washed away by the shearing action of the oxyacetylene flame. The evaporation of SiO2 took away large amount of heat, which is also beneficial to the protection for SiCf/SiO2 composites.

  7. Studies on Kondo insulating FeSi

    International Nuclear Information System (INIS)

    Bharathi, A.; Mani, Awadhesh; Ravindran, Nithya; Mathi Jaya, S.; Sundar, C.S.; Hariharan, Y.

    2000-01-01

    Temperature dependent electrical resistivity measurements have been carried out in Fe (1-x) Ru x Si and FeSi (1-x) Ge x to examine the robustness of the Kondo Insulating gap to substitution in the Fe and Si sublattices. The gap is seen to decrease with Ge substitution, while for Ru substitution the gap shows an initial decrease followed by an increase at higher concentration. The results can be understood in terms of the shift in the mobility edge due to disorder and/or pressure effects in combination with changes in band structure

  8. Properties of tribology for Si implanted PET

    International Nuclear Information System (INIS)

    Wu Yuguang; Zhang Tonghe; Zhang Xu; Liu Andong; Xie Mengxia; Zhang Aimin; Chen Jianmin

    2002-01-01

    Polyethylene terephthalate (PET) has been modified with Si ions from a metal vapor arc source (MEVVA). After implantation, the surface structure has been greatly changed. The experimental results of infrared absorption indicated that the particles are referred to rich carbon and SiC particles. The PET has been strengthened by these dispersed particles. The measurement results using nanometer hardness tester reveal that both surface hardness and modulus increase obviously. Therefore the surface wear resistance improved extremely. Finally the modification mechanism of Si implanted PET was discussed

  9. Implantation of P ions in SiO{sub 2} layers with embedded Si nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kachurin, G.A. E-mail: kachurin@isp.nsc.ru; Cherkova, S.G.; Volodin, V.A.; Kesler, V.G.; Gutakovsky, A.K.; Cherkov, A.G.; Bublikov, A.V.; Tetelbaum, D.I

    2004-08-01

    The effect of 10{sup 13}-10{sup 16} cm{sup -2} P ions implantation and of subsequent annealing on Si nanocrystals (Si-ncs), formed preliminarily in SiO{sub 2} layers by the ion-beam synthesis, has been studied. Photoluminescence (PL), Raman spectroscopy, high resolution electron microscopy (HREM), X-Ray Photoelectron Spectroscopy (XPS) and optical absorption were used for characterizations. The low fluence implantations have shown even individual displacements in Si-ncs quench their PL. Restoration of PL from partly damaged Si-ncs proceeds at annealing less than 1000 deg. C. In the low fluence implanted and annealed samples an increased Si-ncs PL has been found and ascribed to the radiation-induced shock crystallization of stressed Si nanoprecipitates. Annealing at temperatures under 1000 deg. C are inefficient when P ion fluences exceed 10{sup 14} cm{sup -2}, thus becoming capable to amorphize Si-ncs. High crystallization temperature of the amorphized Si-ncs is attributed to a counteraction of their shell layers. After implantation of the highest P fluences an enhanced recovery of PL was found from P concentration over 0.1 at.%. Raman spectroscopy and HREM showed an increased Si-ncs number in such layers. The effect resembles the impurity-enhanced crystallization, known for heavily doped bulk Si. This effect, along with the data obtained by XPS, is considered as an indication P atoms are really present inside the Si-ncs. However, no evidence of free electrons appearance has been observed. The fact is explained by an increased interaction of electrons with the donor nuclei in Si-ncs.

  10. Implantation of P ions in SiO2 layers with embedded Si nanocrystals

    International Nuclear Information System (INIS)

    Kachurin, G.A.; Cherkova, S.G.; Volodin, V.A.; Kesler, V.G.; Gutakovsky, A.K.; Cherkov, A.G.; Bublikov, A.V.; Tetelbaum, D.I.

    2004-01-01

    The effect of 10 13 -10 16 cm -2 P ions implantation and of subsequent annealing on Si nanocrystals (Si-ncs), formed preliminarily in SiO 2 layers by the ion-beam synthesis, has been studied. Photoluminescence (PL), Raman spectroscopy, high resolution electron microscopy (HREM), X-Ray Photoelectron Spectroscopy (XPS) and optical absorption were used for characterizations. The low fluence implantations have shown even individual displacements in Si-ncs quench their PL. Restoration of PL from partly damaged Si-ncs proceeds at annealing less than 1000 deg. C. In the low fluence implanted and annealed samples an increased Si-ncs PL has been found and ascribed to the radiation-induced shock crystallization of stressed Si nanoprecipitates. Annealing at temperatures under 1000 deg. C are inefficient when P ion fluences exceed 10 14 cm -2 , thus becoming capable to amorphize Si-ncs. High crystallization temperature of the amorphized Si-ncs is attributed to a counteraction of their shell layers. After implantation of the highest P fluences an enhanced recovery of PL was found from P concentration over 0.1 at.%. Raman spectroscopy and HREM showed an increased Si-ncs number in such layers. The effect resembles the impurity-enhanced crystallization, known for heavily doped bulk Si. This effect, along with the data obtained by XPS, is considered as an indication P atoms are really present inside the Si-ncs. However, no evidence of free electrons appearance has been observed. The fact is explained by an increased interaction of electrons with the donor nuclei in Si-ncs

  11. Reduced Pressure-Chemical Vapour Deposition of Si/SiGe heterostructures for nanoelectronics

    International Nuclear Information System (INIS)

    Hartmann, J.M.; Andrieu, F.; Lafond, D.; Ernst, T.; Bogumilowicz, Y.; Delaye, V.; Weber, O.; Rouchon, D.; Papon, A.M.; Cherkashin, N.

    2008-01-01

    We have first of all quantified the impact of pressure on Si and SiGe growth kinetics. Definite growth rate and Ge concentration increases with the pressure have been evidenced at low temperatures (650-750 deg. C). By contrast, the high temperature (950-1050 deg. C) Si growth rate either increases or decreases with pressure (gaseous precursor depending). We have then described the selective epitaxial growth process we use to form Si or Si 0.7 Ge 0.3 :B raised sources and drains on ultra-thin patterned Silicon-On-Insulator (SOI) substrates. We have afterwards presented the specifics of SiGe virtual substrates and of the tensile-strained Si layers grown on top (used as templates for the elaboration of tensily strained-SOI wafers). The tensile strain, which can be tailored from 1.3 up to 3 GPa, leads to an electron mobility gain by a factor of 2 in n-Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) built on top. High Ge content SiGe virtual substrates can also be used for the elaboration of compressively strained Ge channels, with impressive hole mobility gains (x9) compared to bulk Si. After that, we have described the main structural features of thick Ge layers grown directly on Si (that can be used as donor wafers for the elaboration of GeOI wafers or as the active medium of near infrared photo-detectors). Finally, we have shown how Si/SiGe multilayers can be used for the formation of high performance 3D devices such as multi-bridge channel or nano-beam gate-all-around FETs, the SiGe sacrificial layers being removed thanks to plasma dry etching, wet etching or in situ gaseous HCl etching

  12. Si cycling in a forest biogeosystem - the importance of transient state biogenic Si pools

    Science.gov (United States)

    Sommer, M.; Jochheim, H.; Höhn, A.; Breuer, J.; Zagorski, Z.; Busse, J.; Barkusky, D.; Meier, K.; Puppe, D.; Wanner, M.; Kaczorek, D.

    2013-07-01

    The relevance of biological Si cycling for dissolved silica (DSi) export from terrestrial biogeosystems is still in debate. Even in systems showing a high content of weatherable minerals, like Cambisols on volcanic tuff, biogenic Si (BSi) might contribute > 50% to DSi (Gerard et al., 2008). However, the number of biogeosystem studies is rather limited for generalized conclusions. To cover one end of controlling factors on DSi, i.e., weatherable minerals content, we studied a forested site with absolute quartz dominance (> 95%). Here we hypothesise minimal effects of chemical weathering of silicates on DSi. During a four year observation period (05/2007-04/2011), we quantified (i) internal and external Si fluxes of a temperate-humid biogeosystem (beech, 120 yr) by BIOME-BGC (version ZALF), (ii) related Si budgets, and (iii) Si pools in soil and beech, chemically as well as by SEM-EDX. For the first time two compartments of biogenic Si in soils were analysed, i.e., phytogenic and zoogenic Si pool (testate amoebae). We quantified an average Si plant uptake of 35 kg Si ha-1 yr-1 - most of which is recycled to the soil by litterfall - and calculated an annual biosilicification from idiosomic testate amoebae of 17 kg Si ha-1. The comparatively high DSi concentrations (6 mg L-1) and DSi exports (12 kg Si ha-1 yr-1) could not be explained by chemical weathering of feldspars or quartz dissolution. Instead, dissolution of a relictic, phytogenic Si pool seems to be the main process for the DSi observed. We identified canopy closure accompanied by a disappearance of grasses as well as the selective extraction of pine trees 30 yr ago as the most probable control for the phenomena observed. From our results we concluded the biogeosystem to be in a transient state in terms of Si cycling.

  13. Si cycling in a forest biogeosystem – the importance of transient state biogenic Si pools

    Directory of Open Access Journals (Sweden)

    M. Sommer

    2013-07-01

    Full Text Available The relevance of biological Si cycling for dissolved silica (DSi export from terrestrial biogeosystems is still in debate. Even in systems showing a high content of weatherable minerals, like Cambisols on volcanic tuff, biogenic Si (BSi might contribute > 50% to DSi (Gerard et al., 2008. However, the number of biogeosystem studies is rather limited for generalized conclusions. To cover one end of controlling factors on DSi, i.e., weatherable minerals content, we studied a forested site with absolute quartz dominance (> 95%. Here we hypothesise minimal effects of chemical weathering of silicates on DSi. During a four year observation period (05/2007–04/2011, we quantified (i internal and external Si fluxes of a temperate-humid biogeosystem (beech, 120 yr by BIOME-BGC (version ZALF, (ii related Si budgets, and (iii Si pools in soil and beech, chemically as well as by SEM-EDX. For the first time two compartments of biogenic Si in soils were analysed, i.e., phytogenic and zoogenic Si pool (testate amoebae. We quantified an average Si plant uptake of 35 kg Si ha−1 yr−1 – most of which is recycled to the soil by litterfall – and calculated an annual biosilicification from idiosomic testate amoebae of 17 kg Si ha−1. The comparatively high DSi concentrations (6 mg L−1 and DSi exports (12 kg Si ha−1 yr−1 could not be explained by chemical weathering of feldspars or quartz dissolution. Instead, dissolution of a relictic, phytogenic Si pool seems to be the main process for the DSi observed. We identified canopy closure accompanied by a disappearance of grasses as well as the selective extraction of pine trees 30 yr ago as the most probable control for the phenomena observed. From our results we concluded the biogeosystem to be in a transient state in terms of Si cycling.

  14. Tunable graphene doping by modulating the nanopore geometry on a SiO2/Si substrate

    KAUST Repository

    Lim, Namsoo

    2018-02-28

    A tunable graphene doping method utilizing a SiO2/Si substrate with nanopores (NP) was introduced. Laser interference lithography (LIL) using a He–Cd laser (λ = 325 nm) was used to prepare pore size- and pitch-controllable NP SiO2/Si substrates. Then, bottom-contact graphene field effect transistors (G-FETs) were fabricated on the NP SiO2/Si substrate to measure the transfer curves. The graphene transferred onto the NP SiO2/Si substrate showed relatively n-doped behavior compared to the graphene transferred onto a flat SiO2/Si substrate, as evidenced by the blue-shift of the 2D peak position (∼2700 cm−1) in the Raman spectra due to contact doping. As the porosity increased within the substrate, the Dirac voltage shifted to a more positive or negative value, depending on the initial doping type (p- or n-type, respectively) of the contact doping. The Dirac voltage shifts with porosity were ascribed mainly to the compensation for the reduced capacitance owing to the SiO2–air hetero-structured dielectric layer within the periodically aligned nanopores capped by the suspended graphene (electrostatic doping). The hysteresis (Dirac voltage difference during the forward and backward scans) was reduced when utilizing an NP SiO2/Si substrate with smaller pores and/or a low porosity because fewer H2O or O2 molecules could be trapped inside the smaller pores.

  15. Chemical vapor deposition of Si/SiC nano-multilayer thin films

    International Nuclear Information System (INIS)

    Weber, A.; Remfort, R.; Woehrl, N.; Assenmacher, W.; Schulz, S.

    2015-01-01

    Stoichiometric SiC films were deposited with the commercially available single source precursor Et_3SiH by classical thermal chemical vapor deposition (CVD) as well as plasma-enhanced CVD at low temperatures in the absence of any other reactive gases. Temperature-variable deposition studies revealed that polycrystalline films containing different SiC polytypes with a Si to carbon ratio of close to 1:1 are formed at 1000 °C in thermal CVD process and below 100 °C in the plasma-enhanced CVD process. The plasma enhanced CVD process enables the reduction of residual stress in the deposited films and offers the deposition on temperature sensitive substrates in the future. In both deposition processes the film thickness can be controlled by variation of the process parameters such as the substrate temperature and the deposition time. The resulting material films were characterized with respect to their chemical composition and their crystallinity using scanning electron microscope, energy dispersive X-ray spectroscopy (XRD), atomic force microscopy, X-ray diffraction, grazing incidence X-ray diffraction, secondary ion mass spectrometry and Raman spectroscopy. Finally, Si/SiC multilayers of up to 10 individual layers of equal thickness (about 450 nm) were deposited at 1000 °C using Et_3SiH and SiH_4. The resulting multilayers features amorphous SiC films alternating with Si films, which feature larger crystals up to 300 nm size as measured by transmission electron microscopy as well as by XRD. XRD features three distinct peaks for Si(111), Si(220) and Si(311). - Highlights: • Stoichiometric silicon carbide films were deposited from a single source precursor. • Thermal as well as plasma-enhanced chemical vapor deposition was used. • Films morphology, crystallinity and chemical composition were characterized. • Silicon/silicon carbide multilayers of up to 10 individual nano-layers were deposited.

  16. Alpha-particle irradiation induced defects in SiO2 films of Si-SiO2 structures

    International Nuclear Information System (INIS)

    Koman, B.P.; Gal'chynskyy, O.V.; Kovalyuk, R.O.; Shkol'nyy, A.K.

    1996-01-01

    The aim of the work was to investigate alpha-particle irradiation induced defects in Si-SiO 2 structures by means of the thermostimulated discharge currents (TSDC) analysis. The object of investigation were (p-Si)-SiO 2 structures formed by a combined oxidation of the industrial p-Si wafers in dry and wet oxygen at temperature of 1150 C. The TSD currents were investigated in the temperature range between 90 and 500 K under linear heating rate. Pu 238 isotopes were the source of alpha-particles with an energy of 4-5 MeV and a density of 5.10 7 s -1 cm -2 . The TSD current curves show two peculiar maxima at about 370 and 480 K. Alpha-particle irradiation doesn't affect the general shape of the TSDC curves but leads to a shift of the maximum at 370 K and reduces the total electret charge which is accumulated in the Si-SiO 2 structures during polarization. The energy distribution function of the defects which are involved in SiO 2 polarization has been calculated. It showes that defects with activation energies of about 0.8 and 1.0 eV take part in forming the electret state, and these activation energies have certain energy distributions. It has been found that the TSDC maximum at 370 K has space charge nature and is caused by migration of hydrogen ions. In irradiated samples hydrogen and natrium ions localize on deeper trapping centres induced by alpha-particle irradiation. (orig.)

  17. C/SiC/MoSi2-Si multilayer coatings for carbon/carbon composites for protection against oxidation

    International Nuclear Information System (INIS)

    Zhang Yulei; Li Hejun; Qiang Xinfa; Li Kezhi; Zhang Shouyang

    2011-01-01

    Highlights: → A C/SiC/MoSi 2 -Si multilayer coating was prepared on C/C by slurry and pack cementation. → Multilayer coating can protect C/C for 300 h at 1873 K or 103 h at 1873 K in air. → The penetration cracks in the coating result in the weight loss of the coated C/C. → The fracture of the coated C/C in wind tunnel result from the excessive local stress. - Abstract: To improve the oxidation resistance of carbon/carbon (C/C) composites, a C/SiC/MoSi 2 -Si multilayer oxidation protective coating was prepared by slurry and pack cementation. The microstructure of the as-prepared coating was characterized by scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. The isothermal oxidation and erosion resistance of the coating was investigated in electrical furnace and high temperature wind tunnel. The results showed that the multilayer coating could effectively protect C/C composites from oxidation in air for 300 h at 1773 K and 103 h at 1873 K, and the coated samples was fractured after erosion for 27 h at 1873 K h in wind tunnel. The weight loss of the coated specimens was considered to be caused by the formation of penetration cracks in the coating. The fracture of the coated C/C composites might result from the excessive local stress in the coating.

  18. Removal of C and SiC from Si and FeSi during ladle refining and solidification

    Energy Technology Data Exchange (ETDEWEB)

    Klevan, Ole Svein

    1997-12-31

    The utilization of solar energy by means of solar cells requires the Si to be very pure. The purity of Si is important for other applications as well. This thesis mainly studies the total removal of carbon from silicon and ferrosilicon. The decarburization includes removal of SiC particles by stirring and during casting in addition to reduction of dissolved carbon by gas purging. It was found that for three commercial qualities of FeSi75, Refined, Gransil, and Standard lumpy, the refined quality is lowest in carbon, followed by Gransil and Standard. A decarburization model was developed that shows the carbon removal by oxidation of dissolved carbon to be a slow process at atmospheric pressure. Gas stirring experiments have shown that silicon carbide particles are removed by transfer to the ladle wall. The casting method of ferrosilicon has a strong influence on the final total carbon content in the commercial alloy. Shipped refined FeSi contains about 100 ppm total carbon, while the molten alloy contains roughly 200 ppm. The total carbon out of the FeSi-furnace is about 1000 ppm. It is suggested that low values of carbon could be obtained on an industrial scale by injection of silica combined with the use of vacuum. Also, the casting system could be designed to give low carbon in part of the product. 122 refs., 50 figs., 24 tabs.

  19. RBS characterization of the deposition of very thin SiGe/SiO2 multilayers by LPCVD

    International Nuclear Information System (INIS)

    Munoz-Martin, A.; Climent-Font, A.; Rodriguez, A.; Sangrador, J.; Rodriguez, T.

    2005-01-01

    Multilayer structures consisting of several alternated layers of SiGe and SiO 2 with thickness ranging from 2 or Si as well as the deposition of SiO 2 on Si show negligible incubation times. The deposition of SiO 2 on SiGe, however, exhibits an incubation time of several minutes, which would be related to the oxidation of the surface necessary for the SiO 2 deposition to start. In all cases the film thickness increases linearly with deposition time, thus allowing the growth rates to be determined. These data allow the deposition process of these very thin layers to be accurately controlled

  20. Study of two-dimensional hole gas at Si/SiGe/Si inverted interface

    International Nuclear Information System (INIS)

    Sadeghazdeh, M.A.; Mironov, O.A.; Parry, C.P.; Philips, P.J.; Parker, E.H.C.; Wahll, T.E.; Emeleus, C.J.

    1998-01-01

    We have studied the transport of two-dimensional hole gas (2DHG) at the inverted interface of a strained Si 0.8 Ge 0.2 quantum well. By application of bias voltage to a Schottky gate on top of this inverted heterostructure the 2DHG density n s can be controlled, in the range of (1.5-5.2)x10 11 cm -2 . At temperature T = 033 K, the Hall mobility is 4650 cm 2 V -1 s -1 at the maximum carrier density. For lower sheet densities (n s 11 cm -2 ) the system undergoes a transition from a weak to strongly localised phase of significantly reduced mobility. From low temperature Shubnikov-de Haas oscillation measurements we have extracted the hole effective masses m* = (0.25 → 0.28)m o and the ratio of transport to quantum lifetimes α = (0.92 → 0.85) for the corresponding carrier density change of n s = (5.2 → 2.5)x10 11 cm -2 . These results can be explained in terms of the abnormal movement of the hole wave function towards the interface with decreasing n s , short range interface roughness scattering. (author)

  1. The Effect of Si Morphology on Machinability of Al-Si Alloys

    Directory of Open Access Journals (Sweden)

    Muhammet Uludağ

    2015-12-01

    Full Text Available Many of the cast parts require some sort of machining like milling, drilling to be used as a finished product. In order to improve the wear properties of Al alloys, Si is added. The solubility of Si in Al is quite low and it has a crystallite type structure. It behaves as particulate metal matrix composite which makes it an attractive element. Thus, the wear and machinability properties of these type of alloys depend on the morphology of Si in the matrix. In this work, Sr was added to alter the morphology of Si in Al-7Si and Al-12Si. Cylindrical shaped samples were cast and machinability characteristics of Sr addition was studied. The relationship between microstructure and machinability was evaluated.

  2. SiC/SiC fuel cladding R and D Project 'SCARLET': Status and future plan

    International Nuclear Information System (INIS)

    Kishimoto, Hirotatsu; Kohyama, Akira

    2015-01-01

    This paper provides the recent progress in SiC/SiC development towards early utilisation for LWRs based on NITE method. After the March 11 Disaster in East-Japan, ensuring safe technology for LWR became a top priority R and D in nuclear energy policy of Japan. Along this line, replacement of Zircaloy claddings with SiC/SiC based fuel cladding is becoming one of the most attractive options and a MEXT fund based project, SCARLET, and a METI fund based project have been launched as 5-year termed projects at Muroran Institute of Technology. These projects care for NITE process for making long SiC/SiC fuel pins and connecting technology integration. The SCARLET project also includes coolant compatibility and irradiation effect evaluations as LWR and LMFBR materials. The outline and the present status of the SCARLET project will be briefly introduced in the present paper. (authors)

  3. Si/SiC heterojunction optically controlled transistor with charge compensation layer

    Directory of Open Access Journals (Sweden)

    Pu Hongbin

    2016-01-01

    Full Text Available A novel n-SiC/p-Si/n-Si optically controlled transistor with charge compensation layer has been studied in the paper. The performance of the device is simulated using Silvaco Atlas tools, which indicates excellent performances of the device in both blocking state and conducting state. The device also has a good switching characteristic with 0.54μs as rising time and 0.66μs as falling time. With the charge compensation layer, the breakdown voltage and the spectral response intensity of the device are improved by 90V and 33A/W respectively. Compared with optically controlled transistor without charge compensation layer, the n-SiC/p-Si/n-Si optically controlled transistor with charge compensation layer has a better performance.

  4. Self-assembled epitaxial NiSi2 nanowires on Si(001) by reactive deposition epitaxy

    International Nuclear Information System (INIS)

    Chen, S.Y.; Chen, L.J.

    2006-01-01

    Self-assembled epitaxial NiSi 2 nanowires have been fabricated on Si(001) by reactive deposition epitaxy (RDE). The RDE method promoted nanowire growth since it provides deposited atoms sufficient kinetic energy for movement on the Si surface during the growth of silicide islands. The twin-related interface between NiSi 2 and Si is directly related to the nanowire formation since it breaks the symmetry of the surface and leads to the asymmetric growth. The temperature of RDE was found to greatly influence the formation of nanowires. By RDE at 750 deg. C, a high density of NiSi 2 nanowires was formed with an average aspect ratio of 30

  5. Structure and chemistry of passivated SiC/SiO{sub 2} interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Houston Dycus, J.; Xu, Weizong; LeBeau, James M. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7907 (United States); Lichtenwalner, Daniel J.; Hull, Brett; Palmour, John W. [Power Devices R& D, Wolfspeed, A Cree Company, Research Triangle Park, North Carolina 27709 (United States)

    2016-05-16

    Here, we report on the chemistry and structure of 4H-SiC/SiO{sub 2} interfaces passivated either by nitric oxide annealing or Ba deposition. Using aberration corrected scanning transmission electron microscopy and spectroscopy, we find that Ba and N remain localized at SiC/SiO{sub 2} interface after processing. Further, we find that the passivating species can introduce significant changes to the near-interface atomic structure of SiC. Specifically, we quantify significant strain for nitric oxide annealed sample where Si dangling bonds are capped by N. In contrast, strain is not observed at the interface of the Ba treated samples. Finally, we place these results in the context of field effect mobility.

  6. The structure modification of Si-SiO2 irradiated by Fe+ ion

    International Nuclear Information System (INIS)

    Jin Tao; Ma Zhongquan; Guo Qi

    1992-01-01

    The effect of the iron ion implantation on the oxide surface and SiO 2 -Si interface of MOS structure was studied by X-ray photo-electron spectroscopy (XPS), and the chemical states of compounds formed were examined. The results obtained show that in the surface layers of SiO 2 the pure Si micro-regions are formed under the implantation and the interface layers of SiO 2 the pure Si micro-regions are formed under the implantation and the interface thickness is almost doubled that leads to failure of MOS capacitors. The physical and chemical mechanisms of MOS structure change by Fe + ion implantation are also discussed and analyzed

  7. SiC Discrete Power Devices

    National Research Council Canada - National Science Library

    Baliga, B

    2000-01-01

    .... The investigation of the poor performance of the 4H-SiC ACCUFETs provided insights for changes in device design and process flow, for improving their breakdown voltage and specific on-resistance...

  8. Mass and QEC value of 26Si

    International Nuclear Information System (INIS)

    Eronen, T.; Elomaa, V.-V.; Hager, U.; Hakala, J.; Jokinen, A.; Kankainen, A.; Kessler, T.; Moore, I. D.; Rahaman, S.; Rissanen, J.; Weber, C.; Aeystoe, J.

    2009-01-01

    The Q EC value of the superallowed β emitter 26 Si has been measured with the JYFLTRAP Penning trap facility to be 4840.85(10) keV which is ten times more precise than any previous measurement. This leaves only the branching ratio to be improved before the Ft value of 26 Si can be used to test the conserved vector current hypothesis. As a consequence, the 25 Al(p,γ) 26 Si reaction Q-value (Q pγ ) was improved to be 5513.7(5) keV, limited now by the mass excess of 25 Al. The new Q pγ value changes the stellar production rate of 26 Si in nova ignition temperatures by about 10%

  9. Illustrations to “Gespräche in dem Reiche derer Todten zwischen dem vortreflichen Moscowitischen Czaar Petro Magno und dem grossen Tyrannen Ivan Basilowiz II” (Peter the Great and Ivan the Terrible by David Fassmann (1725

    Directory of Open Access Journals (Sweden)

    Ekaterina A. Skvortcova

    2017-12-01

    Full Text Available The journal created by David Fassmann (1683–1744, Gespräche in dem Reiche derer Todten, edited in Leipzig, was a huge success. Each of the 240 issues presents a dialogue between two historical figures from the afterworld. In the 83rd–86th Entrevuë, the interlocutors are Peter the Great and Ivan the Terrible. The texts of the four conversations were thoroughly examined by Eckhard Matthes (1987. The present paper explores how the illustrations to the 83rd–86th Entrevuë visualize the texts, which is significant as they were an important instrument for disseminating certain notions about Russia. While the illustration to the first dialogue of the suite juxtaposes Peter and Ivan, the illustration to the second one emphasizes the similarities between them. So the image of the “tyrant” and “barbarian” Ivan becomes a reference point with which a reader is urged to compare Peter’s deeds, seeing not only the differences but also the similarities. This greatly contributes to the creation of the multifaceted image of Russia of the early 18th century. The characters of the second illustration—a tiger and an executioner—can be identified as Ivan and Peter only if the reader takes into consideration an epigram to the illustration, the illustration to the previous dialogue, the text of the next Entrevuë, and facts about the execution of the strel’tsy known from other texts and images, about which Fassmann remains silent in the spirit of ars dissimulandi, which was typical for baroque culture. The paper offers an attempt to trace the iconography of the tyrant as a tiger. In the frontispiece to the 85th Entrevuë, a secretary bringing news from the world of the living and a portrait of Catherine I emphasize the connection of the past and the present, i.e., history and policy. Finally, the illustration to the last dialogue of the series returns to the glorification of Peter the Great declared in the first dialogue.

  10. Prefazione—aspetti relativi al benessere animale nel trasporto a lunga distanza

    Directory of Open Access Journals (Sweden)

    Gardner Murray

    2008-03-01

    veterinario e di sanità animale. Riconoscendone l'importanza, la World Organisation for Animal Health (Office International des Épizooties: OIE nel suo IV piano Strategico (punti a e b, ha identificato il benessere animale come tema chiave ed ha lanciato una serie di iniziative come lo sviluppo di linee guida per il benessere animale comuni per istruire i paesi, le industrie ed il pubblico in genere sulle pratiche più appropriate. Le risultanti linee guide dell'OIE per il trasporto di animali via mare e terra hanno fornito l'indispensabile punto di riferimento per ulteriori sviluppi futuri.Questo numero di Veterinaria Italiana si occupa di trasporto del bestiame. Non è una semplice collazione di articoli scientifici sull'argomento. Piuttosto, la sua unicità deriva dal fatto che fornisce un'indicazione e una guida sulle misure pratiche per migliorare l'approccio basato su dati scientifici. Politici, analisti del rischio, legislatori, manager della qualità, progettisti e formatori, avranno grandi vantaggi da questo numero, che servirà come documento di riferimento sull'argomento.Il ruolo dei veterinari e dei sevizi veterinari nel fornire guida ed indicazioni su benessere, sanità e allevamento di animali è fondamentale e non va sottovalutato. Essi hanno la grande responsabilità di occuparsi di questo argomento e grazie alle competenze acquisite, possono ‘fare la differenza’ nel supportare il continuo miglioramento del benessere e della sanità animale.

  11. Ternary alloying study of MoSi2

    International Nuclear Information System (INIS)

    Yi, D.; Li, C.; Akselsen, O.M.; Ulvensoen, J.H.

    1998-01-01

    Ternary alloying of MoSi 2 with adding a series of transition elements was investigated by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). Iron, Co, Ni, Cr, V, Ti, and Nb were chosen as alloying elements according to the AB 2 structure map or the atomic size factor. The studied MoSi 2 base alloys were prepared by the arc melting process from high-purity metals. The EDS analysis showed that Fe, Co, and Ni have no solid solubility in as-cast MoSi 2 , while Cr, V, Ti, and Nb exhibit limited solid solubilities, which were determined to be 1.4 ± 0.7, 1.4 ± 0.4, 0.4 ± 0.1, and 0.8 ± 0.1. Microstructural characterization indicated that Mo-Si-M VIII (M VIII = Fe, Co, Ni) and Mo-Si-Cr alloys have a two-phase as-cast microstructure, i.e., MoSi 2 matrix and the second-phase FeSi 2 , CoSi, NiSi 2 , and CrSi 2 , respectively. In as-cast Mo-Si-V, Mo-Si-Ti, and Mo-Si-Nb alloys, besides MoSi 2 and C40 phases, the third phases were observed, which have been identified to be (Mo, V) 5 Si 3 , TiSi 2 , and (Mo, Nb) 5 Si 3

  12. Si-Sb-Te materials for phase change memory applications

    International Nuclear Information System (INIS)

    Rao Feng; Song Zhitang; Ren Kun; Zhou Xilin; Cheng Yan; Wu Liangcai; Liu Bo

    2011-01-01

    Si-Sb-Te materials including Te-rich Si 2 Sb 2 Te 6 and Si x Sb 2 Te 3 with different Si contents have been systemically studied with the aim of finding the most suitable Si-Sb-Te composition for phase change random access memory (PCRAM) use. Si x Sb 2 Te 3 shows better thermal stability than Ge 2 Sb 2 Te 5 or Si 2 Sb 2 Te 6 in that Si x Sb 2 Te 3 does not have serious Te separation under high annealing temperature. As Si content increases, the data retention ability of Si x Sb 2 Te 3 improves. The 10 years retention temperature for Si 3 Sb 2 Te 3 film is ∼ 393 K, which meets the long-term data storage requirements of automotive electronics. In addition, Si richer Si x Sb 2 Te 3 films also show improvement on thickness change upon annealing and adhesion on SiO 2 substrate compared to those of Ge 2 Sb 2 Te 5 or Si 2 Sb 2 Te 6 films. However, the electrical performance of PCRAM cells based on Si x Sb 2 Te 3 films with x > 3.5 becomes worse in terms of stable and long-term operations. Si x Sb 2 Te 3 materials with 3 < x < 3.5 are proved to be suitable for PCRAM use to ensure good overall performance.

  13. RBS using {sup 28}Si beams

    Energy Technology Data Exchange (ETDEWEB)

    Ophel, T.R. [Australian National Univ., Canberra, ACT (Australia); Mitchell, I.V. [University of Western Ontario, London, ON (Canada). Dept. of Physics

    1996-12-31

    Measurements of RBS using {sup 28}Si beams have been made to evaluate the enhancement of sensitivity that should obtain from kinematic suppression of silicon substrate scattering. Two detection methods were tried. Aside from a surface barrier detector, a magnetic spectrometer, instrumented with a multi-electrode gas focal plane detector, was used to indicate the resolution attainable with low energy {sup 28}Si ions. The results confirm that kinematically suppressed RBS does provide greatly improved sensitivity. 5 refs., 2 figs.

  14. RBS using {sup 28}Si beams

    Energy Technology Data Exchange (ETDEWEB)

    Ophel, T R [Australian National Univ., Canberra, ACT (Australia); Mitchell, I V [University of Western Ontario, London, ON (Canada). Dept. of Physics

    1997-12-31

    Measurements of RBS using {sup 28}Si beams have been made to evaluate the enhancement of sensitivity that should obtain from kinematic suppression of silicon substrate scattering. Two detection methods were tried. Aside from a surface barrier detector, a magnetic spectrometer, instrumented with a multi-electrode gas focal plane detector, was used to indicate the resolution attainable with low energy {sup 28}Si ions. The results confirm that kinematically suppressed RBS does provide greatly improved sensitivity. 5 refs., 2 figs.

  15. Silicon Photonics Cloud (SiCloud)

    DEFF Research Database (Denmark)

    DeVore, P. T. S.; Jiang, Y.; Lynch, M.

    2015-01-01

    Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths.......Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths....

  16. Surface acoustic wave devices on AlN/3C–SiC/Si multilayer structures

    International Nuclear Information System (INIS)

    Lin, Chih-Ming; Lien, Wei-Cheng; Riekkinen, Tommi; Senesky, Debbie G; Pisano, Albert P; Chen, Yung-Yu; Felmetsger, Valery V

    2013-01-01

    Surface acoustic wave (SAW) propagation characteristics in a multilayer structure including a piezoelectric aluminum nitride (AlN) thin film and an epitaxial cubic silicon carbide (3C–SiC) layer on a silicon (Si) substrate are investigated by theoretical calculation in this work. Alternating current (ac) reactive magnetron sputtering was used to deposit highly c-axis-oriented AlN thin films, showing the full width at half maximum (FWHM) of the rocking curve of 1.36° on epitaxial 3C–SiC layers on Si substrates. In addition, conventional two-port SAW devices were fabricated on the AlN/3C–SiC/Si multilayer structure and SAW propagation properties in the multilayer structure were experimentally investigated. The surface wave in the AlN/3C–SiC/Si multilayer structure exhibits a phase velocity of 5528 m s −1 and an electromechanical coupling coefficient of 0.42%. The results demonstrate the potential of AlN thin films grown on epitaxial 3C–SiC layers to create layered SAW devices with higher phase velocities and larger electromechanical coupling coefficients than SAW devices on an AlN/Si multilayer structure. Moreover, the FWHM values of rocking curves of the AlN thin film and 3C–SiC layer remained constant after annealing for 500 h at 540 °C in air atmosphere. Accordingly, the layered SAW devices based on AlN thin films and 3C–SiC layers are applicable to timing and sensing applications in harsh environments. (paper)

  17. Si nanoparticle-decorated Si nanowire networks for Li-ion battery anodes

    KAUST Repository

    Hu, Liangbing

    2011-01-01

    We designed and fabricated binder-free, 3D porous silicon nanostructures for Li-ion battery anodes, where Si nanoparticles electrically contact current collectors via vertically grown silicon nanowires. When compared with a Si nanowire anode, the areal capacity was increased by a factor of 4 without having to use long, high temperature steps under vacuum that vapour-liquid-solid Si nanowire growth entails. © 2011 The Royal Society of Chemistry.

  18. Antioxidant migration resistance of SiOx layer in SiOx/PLA coated film.

    Science.gov (United States)

    Huang, Chongxing; Zhao, Yuan; Su, Hongxia; Bei, Ronghua

    2018-02-01

    As novel materials for food contact packaging, inorganic silicon oxide (SiO x ) films are high barrier property materials that have been developed rapidly and have attracted the attention of many manufacturers. For the safe use of SiO x films for food packaging it is vital to study the interaction between SiO x layers and food contaminants, as well as the function of a SiO x barrier layer in antioxidant migration resistance. In this study, we deposited a SiO x layer on polylactic acid (PLA)-based films to prepare SiO x /PLA coated films by plasma-enhanced chemical vapour deposition. Additionally, we compared PLA-based films and SiO x /PLA coated films in terms of the migration of different antioxidants (e.g. t-butylhydroquinone [TBHQ], butylated hydroxyanisole [BHA], and butylated hydroxytoluene [BHT]) via specific migration experiments and then investigated the effects of a SiO x layer on antioxidant migration under different conditions. The results indicate that antioxidant migration from SiO x /PLA coated films is similar to that for PLA-based films: with increase of temperature, decrease of food simulant polarity, and increase of single-sided contact time, the antioxidant migration rate and amount in SiO x /PLA coated films increase. The SiO x barrier layer significantly reduced the amount of migration of antioxidants with small and similar molecular weights and similar physical and chemical properties, while the degree of migration blocking was not significantly different among the studied antioxidants. However, the migration was affected by temperature and food simulant. Depending on the food simulants considered, the migration amount in SiO x /PLA coated films was reduced compared with that in PLA-based films by 42-46%, 44-47%, and 44-46% for TBHQ, BHA, and BHT, respectively.

  19. SiPM properties at cryogenic temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Biroth, Maik; Achenbach, Patrick; Thomas, Andreas [Institut fuer Kernphysik, Johannes Gutenberg-Universitaet, Mainz (Germany); Downie, Evangeline [George Washington University, DC (United States); Collaboration: A2-Collaboration

    2015-07-01

    At the electron accelerator Mainzer Mikrotron (MAMI) an active target build of polarizable scintillators will be operated at approximately 25 mK. To read out the scintillation light, the photodetectors have to withstand cryogenic temperatures of 4 K and high count rates. Therefore the properties of different types of silicon photomultipliers (SiPMs) were studied at cryogenic temperatures. In liquid nitrogen at 77 K, problems with quenching in Hamamatsu SiPMs and with the protective epoxy layer covering Zecotek SiPMs were observed. Tests with one Zecotek SiPM were successful after removal of the epoxy layer in liquid helium at 4 K and no after-pulses could be observed. Fundamental parameters like break-down voltage, single-pixel gain, crosstalk probability and the dark-count rate were measured and compared to room temperature. The photon detection efficiency was estimated by SiPMs response to short LED pulses. All these parameters were extracted by curve-fitting of SiPM charge spectra with a new analytical function.

  20. Separation of stress-free AlN/SiC thin films from Si substrate

    International Nuclear Information System (INIS)

    Redkov, A V; Osipov, A V; Mukhin, I S; Kukushkin, S A

    2016-01-01

    We separated AlN/SiC film from Si substrate by chemical etching of the AlN/SiC/Si heterostructure. The film fully repeats the size and geometry of the original sample and separated without destroying. It is demonstrated that a buffer layer of silicon carbide grown by a method of substitution of atoms may have an extensive hollow subsurface structure, which makes it easier to overcome the differences in the coefficients of thermal expansion during the growth of thin films. It is shown that after the separation of the film from the silicon substrate, mechanical stresses therein are almost absent. (paper)

  1. Transformation of point defects under annealing of neutron-irradiated Si and Si:Ge

    International Nuclear Information System (INIS)

    Pomozov, Yu.V.; Khirunenko, L.I.; Shakhovtsev, V.I.; Yashnik, V.I.

    1990-01-01

    Transformation of point radiation defects under isochronous annealing of neurton-irradaited Si and Si:Ge is studied. It is determined, that occurence of several new centers which produce A-centre range absorption bands is observed at annealing within 423-493 K temperature range. It is shown that vacancy and oxygen are included in the centers composition. It is found that VO centre transformation into VO 2 at annealing occurs via intermediate stage in contrast to that occuring in electron-irradiated crystals via VO direct diffusion to interstitial oxygen. Transformation of centers under Si ansd Si:Ge annealing occurs similarly

  2. Stability of Ta-encapsulating Si clusters on Si(111)-(7x7) surfaces

    CERN Document Server

    Uchida, N; Miyazaki, T; Kanayama, T

    2003-01-01

    Tantalum containing Si cluster ions TaSi sub 1 sub 0 sub - sub 1 sub 3 H sub x sup + were synthesized in an ion trap and deposited onto Si(111)-(7x7) surfaces with a kinetic energy of 18 eV. Scanning tunnelling microscope observations revealed that the clusters adsorbed on the surface without decomposition, consistent with ab initio calculation results, that predicted the clusters would have stable Si-cage structures with a Ta atom at the centre. (rapid communication)

  3. Vertical epitaxial wire-on-wire growth of Ge/Si on Si(100) substrate.

    Science.gov (United States)

    Shimizu, Tomohiro; Zhang, Zhang; Shingubara, Shoso; Senz, Stephan; Gösele, Ulrich

    2009-04-01

    Vertically aligned epitaxial Ge/Si heterostructure nanowire arrays on Si(100) substrates were prepared by a two-step chemical vapor deposition method in anodic aluminum oxide templates. n-Butylgermane vapor was employed as new safer precursor for Ge nanowire growth instead of germane. First a Si nanowire was grown by the vapor liquid solid growth mechanism using Au as catalyst and silane. The second step was the growth of Ge nanowires on top of the Si nanowires. The method presented will allow preparing epitaxially grown vertical heterostructure nanowires consisting of multiple materials on an arbitrary substrate avoiding undesired lateral growth.

  4. Next Generation, Si-Compatible Materials and Devices in the Si-Ge-Sn System

    Science.gov (United States)

    2015-10-09

    and conclusions The work initially focused on growth of next generation Ge1-ySny alloys on Ge buffered Si wafers via UHV CVD depositions of Ge3H8...Abstract The work initially focused on growth of next generation Ge1-ySny alloys on Ge buffered Si wafers via UHV CVD depositions of Ge3H8, SnD4. The...AFRL-AFOSR-VA-TR-2016-0044 Next generation, Si -compatible materials and devices in the Si - Ge -Sn system John Kouvetakis ARIZONA STATE UNIVERSITY Final

  5. SiNx layers on nanostructured Si solar cells: Effective for optical absorption and carrier collection

    International Nuclear Information System (INIS)

    Cho, Yunae; Kim, Eunah; Gwon, Minji; Kim, Dong-Wook; Park, Hyeong-Ho; Kim, Joondong

    2015-01-01

    We compared nanopatterned Si solar cells with and without SiN x layers. The SiN x layer coating significantly improved the internal quantum efficiency of the nanopatterned cells at long wavelengths as well as short wavelengths, whereas the surface passivation helped carrier collection of flat cells mainly at short wavelengths. The surface nanostructured array enhanced the optical absorption and also concentrated incoming light near the surface in broad wavelength range. Resulting high density of the photo-excited carriers near the surface could lead to significant recombination loss and the SiN x layer played a crucial role in the improved carrier collection of the nanostructured solar cells

  6. White photoluminescence from Si/SiO{sub 2} nanostructured film

    Energy Technology Data Exchange (ETDEWEB)

    Duong, P.H.; Ngan, N.T.T.; Tuan, C.A. [Institute of Materials Science, Vietnamese Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam); Huy, P.T. [International Training Institute of Materials Science, Hanoi University of Technology, 1 Dai Co Viet, Hanoi (Viet Nam); Itoh, T. [Graduate School of Engineering Science, Osaka University, Toyonaka (Japan)

    2008-12-15

    We present in this work the results of PL measurement of Si-NC embedded in Si/SiO{sub 2} multilayer system. A very intense broad luminescence band was observed in the sample under illumination in vacuum by UV laser line. The PL intensity enhancement and quenching effect observed in different ambients can be attributed to the energy exchange from NC to MO. The storage of the annealed sample in vacuum for a long time drastically changed the PL properties of Si-NC. The origin of these phenomena will be discussed. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Specimen size effect considerations for irradiation studies of SiC/SiC

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, G.E.; Henager, C.H. Jr.; Jones, R.H. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-10-01

    For characterization of the irradiation performance of SiC/SiC, limited available irradiation volume generally dictates that tests be conducted on a small number of relatively small specimens. Flexure testing of two groups of bars with different sizes cut from the same SiC/SiC plate suggested the following lower limits for flexure specimen number and size: Six samples at a minimum for each condition and a minimum bar size of 30 x 6.0 x 2.0 mm{sup 3}.

  8. Residual stresses and mechanical properties of Si3N4/SiC multilayered composites with different SiC layers

    International Nuclear Information System (INIS)

    Liua, S.; Lia, Y.; Chena, P.; Lia, W.; Gaoa, S.; Zhang, B.; Yeb, F.

    2017-01-01

    The effect of residual stresses on the strength, toughness and work of fracture of Si3N4/SiC multilayered composites with different SiC layers has been investigated. It may be an effective way to design and optimize the mechanical properties of Si3N4/SiC multilayered composites by controlling the properties of SiC layers. Si3N4/SiC multilayered composites with different SiC layers were fabricated by aqueous tape casting and pressureless sintering. Residual stresses were calculated by using ANSYS simulation, the maximum values of tensile and compressive stresses were 553.2MPa and −552.1MPa, respectively. Step-like fracture was observed from the fracture surfaces. Fraction of delamination layers increased with the residual stress, which can improve the reliability of the materials. Tensile residual stress was benefit to improving toughness and work of fracture, but the strength of the composites decreased. [es

  9. Marker experiments in growth studies of Ni2Si, Pd2Si, and CrSi2 formed both by thermal annealing and by ion mixing

    International Nuclear Information System (INIS)

    Hung, L.S.; Mayer, J.W.; Pai, C.S.; Lau, S.S.

    1985-01-01

    Inert markers (evaporated tungsten and silver) were used in growth studies of silicides formed both by thermal annealing and by ion mixing in the Ni/Si, Pd/Si, and Cr/Si systems. The markers were initially imbedded inside silicides and backscattering spectrometry was used to determine the marker displacement after different processing conditions. The results obtained in thermal annealing are quite consistent with that found in previous investigations. Ni is the dominant diffusing species in Ni 2 Si, while Si is the diffusing species in CrSi 2 . In Pd 2 Si, both Pd and Si are moving species with Pd the faster of the two. In contrast, in growth of silicides by ion irradiation Si is the faster diffusing species in all three systems

  10. Silicon electrodeposition from chloride-fluoride melts containing K2SiF6 and SiO2

    Directory of Open Access Journals (Sweden)

    Zhuk Sergey I.

    2017-01-01

    Full Text Available Silicon electrodeposition on glassy carbon from the KF-KCl-K2SiF6, KF-KCl-K2SiF6-KOH and KF-KCl-K2SiF6-SiO2 melts was studied by the cyclic voltammetry. Тhe electroreduction of Si(IV to metallic Si was observed as a single 4-electron wave under all considered conditions. The reactions of cathode reduction of silicon from fluoride and oxyfluoride complexes were suggested. It was shown that the process can be controlled by the preliminary transformation of SiO44- to SiF62- and SiOxFyz-. The influence of the current density on structure and morphology of silicon deposits obtained during galvanostatic electrolysis of the KF-KCl-K2SiF6-SiO2 melt was studied.

  11. ALLA SCOPERTA DEL PACKAGING DESIGN CON IL WEBQUEST

    Directory of Open Access Journals (Sweden)

    Antonietta Gobbis

    2013-01-01

    Full Text Available Il seguente saggio tratta le possibilità di presentazione in Università straniere, dove si insegna l’ItalianoL2, di un aspetto culturale italiano di forte impatto all’estero come il design, attraverso l’innovativa metodologia del webquest. L’iniziale parte teorica descrive il webquest come metodo didattico costruttivista, con particolare riferimento alle sue caratteristiche, parti costituenti e tipologie. Nella seconda parte vengono dati esempi concreti di webquest di breve e lunga durata su due prodotti italiani molto famosi di packaging design, che hanno festeggiato il loro anniversario nel 2012: il Bacio Perugina e il Campari Soda. I risultati positivi di entrambi i progetti intendono mostrare i vantaggi di una didattica centrata sull’alunno basata su attività di problem-solving e strategie di cooperative learning.  Discovering packaging design through webquest The following essay deals about the possibilities to introduce a very successful cultural topic like Italian Design in Universities abroad, where Italian is taught as second foreign language, through the innovative methodology of WebQuests. The theoretical part describes WebQuests as constructivist didactic method with reference to its characteristics, main constituent parts  and typologies. In the second part we give concrete examples of short and long term WebQuests about two very famous packaging design Italian products which celebrated in 2012 their anniversary: BacioPerugina and Campari Soda. The positive results of both projects aim to show the advantages of learner-centered teaching methods based on problem-solving activities and cooperative learning strategies.

  12. Phytoextraction. A new pilot-plant project for the soil decontamination; Fitodecontaminazione. Un sistema pilota per la fito-decontaminazione di suoli inquinati da piombo

    Energy Technology Data Exchange (ETDEWEB)

    Bregante, M.; Paganetto, A.; Magistrelli, P.; Martella, L.; Gambale, F. [Consiglio Nazionale delle Ricerche, Istituto di Cibernetica e Biofisica, Genoa (Italy); Sacchi, G.A.; Rivetta, A.; Cocucci, R. [Milan Univ., Milan (Italy). Dipt. di Produzione Vegetale

    2001-12-01

    The environmental pollution is continuously increasing owing to anthropic activity. High concentrations of heavy metals may have drastic consequences on human health, particularly on children development. Conventional approaches have high economical and environmental costs that do not allow soil decontamination unless sites are particularly valuable. Phytoextraction uses plants producing biomass to transfer metals from the soil to the aerial parts of the plants at the expenses of solar energy. This work illustrates the activity performed within a Life-Environment european project in order to verify whether phytoremediation can be transferred from the laboratory scale to the field scale. [Italian] L'inquinamento del suolo dovuto all'accumulo di metalli come conseguenza delle attivita' umane sta continuamente e drammaticamente aumentando. Principali cause di contaminazione sono l'accumulo di rifiuti urbani, l'utilizzo di fertilizzanti, il traffico motorizzato, gli inceneritori, le centrali termoelettriche, le emissiioni industriali nocive, lo sfruttamento e dismissione di miniere. La decontaminazione di suoli inquinati da metalli e' un problema estremamente difficile da trattare. La bonifica di suoli inquinati da metalli mediante l'utilizzo di piante metallofite e/o agronomiche (fitoestrazione) emerge quindi come una tecnica estremamente interessante. Viene percio' illustrato il progetto PhyLeS (Phytoextraction of Lead from Soil), un progetto pilota finanziato dal programma Europeo Life/Ambiente (DG XI), che si propone di verficare i potenziali vantaggi e la trasferibilita' della metodica di fitoestrazione assistita dalla scala di laboratorio a quella di campo.

  13. MeV Si ion modifications on the thermoelectric generators from Si/Si + Ge superlattice nano-layered films

    Science.gov (United States)

    Budak, S.; Heidary, K.; Johnson, R. B.; Colon, T.; Muntele, C.; Ila, D.

    2014-08-01

    The performance of thermoelectric materials and devices is characterized by a dimensionless figure of merit, ZT = S2σT/K, where, S and σ denote, respectively, the Seebeck coefficient and electrical conductivity, T is the absolute temperature in Kelvin and K represents the thermal conductivity. The figure of merit may be improved by means of raising either S or σ or by lowering K. In our laboratory, we have fabricated and characterized the performance of a large variety of thermoelectric generators (TEG). Two TEG groups comprised of 50 and 100 alternating layers of Si/Si + Ge multi-nanolayered superlattice films have been fabricated and thoroughly characterized. Ion beam assisted deposition (IBAD) was utilized to assemble the alternating sandwiched layers, resulting in total thickness of 300 nm and 317 nm for 50 and 100 layer devices, respectively. Rutherford Backscattering Spectroscopy (RBS) was employed in order to monitor the precise quantity of Si and Ge utilized in the construction of specific multilayer thin films. The material layers were subsequently impregnated with quantum dots and/or quantum clusters, in order to concurrently reduce the cross plane thermal conductivity, increase the cross plane Seebeck coefficient and raise the cross plane electrical conductivity. The quantum dots/clusters were implanted via the 5 MeV Si ion bombardment which was performed using a Pelletron high energy ion beam accelerator. We have achieved remarkable results for the thermoelectric and optical properties of the Si/Si + Ge multilayer thin film TEG systems. We have demonstrated that with optimal setting of the 5 MeV Si ion beam bombardment fluences, one can fabricate TEG systems with figures of merits substantially higher than the values previously reported.

  14. MeV Si ion modifications on the thermoelectric generators from Si/Si + Ge superlattice nano-layered films

    Energy Technology Data Exchange (ETDEWEB)

    Budak, S., E-mail: satilmis.budak@aamu.edu [Department of Electrical Engineering and Computer Science, Alabama A and M University, Huntsville, AL (United States); Heidary, K. [Department of Electrical Engineering and Computer Science, Alabama A and M University, Huntsville, AL (United States); Johnson, R.B.; Colon, T. [Department of Physics, Alabama A and M University, Huntsville, AL (United States); Muntele, C. [Cygnus Scientific Services, Huntsville, AL (United States); Ila, D. [Department of Physics, Fayetteville St. University, Fayetteville, NC (United States)

    2014-08-15

    The performance of thermoelectric materials and devices is characterized by a dimensionless figure of merit, ZT = S{sup 2}σT/K, where, S and σ denote, respectively, the Seebeck coefficient and electrical conductivity, T is the absolute temperature in Kelvin and K represents the thermal conductivity. The figure of merit may be improved by means of raising either S or σ or by lowering K. In our laboratory, we have fabricated and characterized the performance of a large variety of thermoelectric generators (TEG). Two TEG groups comprised of 50 and 100 alternating layers of Si/Si + Ge multi-nanolayered superlattice films have been fabricated and thoroughly characterized. Ion beam assisted deposition (IBAD) was utilized to assemble the alternating sandwiched layers, resulting in total thickness of 300 nm and 317 nm for 50 and 100 layer devices, respectively. Rutherford Backscattering Spectroscopy (RBS) was employed in order to monitor the precise quantity of Si and Ge utilized in the construction of specific multilayer thin films. The material layers were subsequently impregnated with quantum dots and/or quantum clusters, in order to concurrently reduce the cross plane thermal conductivity, increase the cross plane Seebeck coefficient and raise the cross plane electrical conductivity. The quantum dots/clusters were implanted via the 5 MeV Si ion bombardment which was performed using a Pelletron high energy ion beam accelerator. We have achieved remarkable results for the thermoelectric and optical properties of the Si/Si + Ge multilayer thin film TEG systems. We have demonstrated that with optimal setting of the 5 MeV Si ion beam bombardment fluences, one can fabricate TEG systems with figures of merits substantially higher than the values previously reported.

  15. On the interplay between Si(110) epilayer atomic roughness and subsequent 3C-SiC growth direction

    Science.gov (United States)

    Khazaka, Rami; Michaud, Jean-François; Vennéguès, Philippe; Nguyen, Luan; Alquier, Daniel; Portail, Marc

    2016-11-01

    In this contribution, we performed the growth of a 3C-SiC/Si/3C-SiC layer stack on a Si(001) substrate by means of chemical vapor deposition. We show that, by tuning the growth conditions, the 3C-SiC epilayer can be grown along either the [111] direction or the [110] direction. The key parameter for the growth of the desired 3C-SiC orientation on the Si(110)/3C-SiC(001)/Si(001) heterostructure is highlighted and is linked to the Si epilayer surface morphology. The epitaxial relation between the layers has been identified using X-ray diffraction and transmission electron microscopy (TEM). We showed that, regardless of the top 3C-SiC epilayer orientation, domains rotated by 90° around the growth direction are present in the epilayer. Furthermore, the difference between the two 3C-SiC orientations was investigated by means of high magnification TEM. The results indicate that the faceted Si(110) epilayer surface morphology results in a (110)-oriented 3C-SiC epilayer, whereas a flat hetero-interface has been observed between 3C-SiC(111) and Si(110). The control of the top 3C-SiC growth direction can be advantageous for the development of new micro-electro-mechanical systems.

  16. A Comprehensive Model of the Dry Desulphurisation Process Une modélisation non empirique du procédé de désulfuration par voie sèche

    Directory of Open Access Journals (Sweden)

    Flament P.

    2006-11-01

    humide des fumées, le procédé de désulfuration par voie sèche reste un moyen attractif pour éliminer le dioxyde de soufre lorsque le taux de réduction souhaité ne dépasse pas 90 %. Dans cette technique, l'élimination du SO2 se fait en injectant directement dans les produits de combustion de très fines particules d'un absorbant calcique tel que le calcaire (CaCO3 ou la chaux (Ca(OH². L'absorbant est tout d'abord transformé en oxyde de calcium (CaO avant de réagir avec le SO2 pour former un composé stable : le sulfate de calcium (CaSO4. Bien que les réactions globales soient extrêmement simples, une description complète des mécanismes nécessite de connaître à la fois, les propriétés physiques initiales de l'absorbant et leur évolution durant la réaction. De plus, les conditions d'injection des particules jouent un rôle prépondérant dans le procédé de désulfuration par voie sèche. Tous ces aspects sont traités dans ce papier. Le modèle de désulfuration a d'abord été testé seul par comparaison avec les données cinétiques de la Fondation Internationale de Recherches sur les Flammes (FRIF, puis, couplé avec le code KIVA, il a été utilisé pour simuler la désulfuration dans un nouveau type de chaudière développée par Babcock Entreprise et l'Institut Français du Pétrole (chaudière 'AUDE'. Dans ce dernier cas, l'objectif poursuivi était de déterminer la meilleure configuration à donner au système d'injection des particules pour obtenir un taux de désulfuration maximum. La dispersion des particules étant un paramètre important du procédé de désulfuration, un exemple de validation du modèle de dispersion est également traité. L'injection de particules dans une couche de mélange a été choisie comme cas test. L'accord entre les valeurs expérimentales de Ando et al. (1990 et les calculs effectués avec KIVA est satisfaisant.

  17. Revision of the Li13Si4 structure.

    Science.gov (United States)

    Zeilinger, Michael; Fässler, Thomas F

    2013-11-06

    Besides Li17Si4, Li16.42Si4, and Li15Si4, another lithium-rich representative in the Li-Si system is the phase Li13Si4 (trideca-lithium tetra-silicide), the structure of which has been determined previously [Frank et al. (1975 ▶). Z. Naturforsch. Teil B, 30, 10-13]. A careful analysis of X-ray diffraction patterns of Li13Si4 revealed discrepancies between experimentally observed and calculated Bragg positions. Therefore, we redetermined the structure of Li13Si4 on the basis of single-crystal X-ray diffraction data. Compared to the previous structure report, decisive differences are (i) the introduction of a split position for one Li site [occupancy ratio 0.838 (7):0.162 (7)], (ii) the anisotropic refinement of atomic displacement parameters for all atoms, and (iii) a high accuracy of atom positions and unit-cell parameters. The asymmetric unit of Li13Si4 contains two Si and seven Li atoms. Except for one Li atom situated on a site with symmetry 2/m, all other atoms are on mirror planes. The structure consists of isolated Si atoms as well as Si-Si dumbbells surrounded by Li atoms. Each Si atom is either 12- or 13-coordinated. The isolated Si atoms are situated in the ab plane at z = 0 and are strictly separated from the Si-Si dumbbells at z = 0.5.

  18. Electrospun a-Si using Liquid Silane/Polymer Inks

    Energy Technology Data Exchange (ETDEWEB)

    Doug Schulz

    2010-12-09

    Amorphous silicon nanowires (a-SiNWs) were prepared by electrospinning cyclohexasilane (Si{sub 6}H{sub 12}) admixed with polymethylmethacrylate (PMMA) in toluene. Raman spectroscopy characterization of these wires (d {approx} 50-2000 nm) shows 350 C treatment yields a-SiNWs. Porous a-SiNWs are obtained using a volatile polymer.

  19. La spirale dell’azzardo: una subcultura del gioco che “evapora” le relazioni / La spirale du jeu de hasard : une sous-culture qui empêche toute relation / The gambling: a subculture of game that “burns” the relationships

    Directory of Open Access Journals (Sweden)

    Molin Valentina

    2011-07-01

    Full Text Available In this paper I have analysed the characteristics of what I define the “gambling subculture”, which is detectable in certain gaming environments and in subgroups of particularly “rabid” players. Within these subcultures there have been identified rules and sanctions, values, consolidate behaviours, characterization of relationships and interactions, and the conclusion is that what is built within the gambling environment is a separate universe, an “outer reality”, in which the values of the world “outside” change. It was also possible to conclude that, to join the gambling world for a gambler – learning its rules, sharing its values, developing relations inside it – represents a stimulus for gambling habits, as it allows to consider as “normal” their behaviour thanks to positive feedback from their groups of fellow players, and to the neutralization of possible negative feedback from “non-players”.Nel presente contributo vengono analizzate le caratteristiche di quella che ho definito “subcultura dell'azzardo”, rilevabile in determinati ambienti ludici e in sotto-gruppi di giocatori particolarmente “accaniti”. Di queste forme di subcultura sono state individuate norme e sanzioni, valori, comportamenti consolidati, caratterizzazione delle relazioni e delle interazioni, giungendo alla conclusione che quello che viene costruito negli spazi di gioco rappresenta un universo separato, un “extraluogo”, nel quale vengono scritte nuove regole e nel quale cambiano i valori rispetto al mondo “esterno”. È stato possibile inoltre concludere che l'adesione all'“universo gioco” – l'interiorizzazione delle sue norme, la condivisione dei suoi valori, lo sviluppo di relazioni al suo interno – rappresenta un fattore di mantenimento della condotta ludica, poiché permette di considerare “normale” il proprio comportamento grazie ai rinforzi positivi che giungono dal gruppo dei compagni-giocatori e alla

  20. Comparative study of SiC- and Si-based photovoltaic inverters

    Science.gov (United States)

    Ando, Yuji; Oku, Takeo; Yasuda, Masashi; Shirahata, Yasuhiro; Ushijima, Kazufumi; Murozono, Mikio

    2017-01-01

    This article reports comparative study of 150-300 W class photovoltaic inverters (Si inverter, SiC inverter 1, and SiC inverter 2). In these sub-kW class inverters, the ON-resistance was considered to have little influence on the efficiency. The developed SiC inverters, however, have exhibited an approximately 3% higher direct current (DC)-alternating current (AC) conversion efficiency as compared to the Si inverter. Power loss analysis indicated a reduction in the switching and reverse recovery losses of SiC metal-oxide-semiconductor field-effect transistors used for the DC-AC converter is responsible for this improvement. In the SiC inverter 2, an increase of the switching frequency up to 100 kHz achieved a state-of-the-art combination of the weight (1.25 kg) and the volume (1260 cm3) as a 150-250 W class inverter. Even though the increased switching frequency should cause the increase of the switching losses, the SiC inverter 2 exhibited an efficiency comparable to the SiC inverter 1 with a switching frequency of 20 kHz. The power loss analysis also indicated a decreased loss of the DC-DC converter built with SiC Schottky barrier diodes led to the high efficiency for its increased switching frequency. These results clearly indicated feasibility of SiC devices even for sub-kW photovoltaic inverters, which will be available for the applications where compactness and efficiency are of tremendous importance.

  1. Mobility-limiting mechanisms in single and dual channel strained Si/SiGe MOSFETs

    International Nuclear Information System (INIS)

    Olsen, S.H.; Dobrosz, P.; Escobedo-Cousin, E.; Bull, S.J.; O'Neill, A.G.

    2005-01-01

    Dual channel strained Si/SiGe CMOS architectures currently receive great attention due to maximum performance benefits being predicted for both n- and p-channel MOSFETs. Epitaxial growth of a compressively strained SiGe layer followed by tensile strained Si can create a high mobility buried hole channel and a high mobility surface electron channel on a single relaxed SiGe virtual substrate. However, dual channel n-MOSFETs fabricated using a high thermal budget exhibit compromised mobility enhancements compared with single channel devices, in which both electron and hole channels form in strained Si. This paper investigates the mobility-limiting mechanisms of dual channel structures. The first evidence of increased interface roughness due to the introduction of compressively strained SiGe below the tensile strained Si channel is presented. Interface corrugations degrade electron mobility in the strained Si. Roughness measurements have been carried out using AFM and TEM. Filtering AFM images allowed roughness at wavelengths pertinent to carrier transport to be studied and the results are in agreement with electrical data. Furthermore, the first comparison of strain measurements in the surface channels of single and dual channel architectures is presented. Raman spectroscopy has been used to study channel strain both before and after processing and indicates that there is no impact of the buried SiGe layer on surface macrostrain. The results provide further evidence that the improved performance of the single channel devices fabricated using a high thermal budget arises from improved surface roughness and reduced Ge diffusion into the Si channel

  2. Si/C and H coadsorption at 4H-SiC{0001} surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wachowicz, E., E-mail: elwira@ifd.uni.wroc.pl [Institute of Experimental Physics, University of Wrocław, Plac M. Borna 9, PL-50-204 Wrocław (Poland); Interdisciplinary Centre for Mathematical and Computational Modelling, University of Warsaw, Pawińskiego 5a, PL-02-106 Warsaw (Poland)

    2016-06-15

    Highlights: • Si on C-terminated and C on Si-terminated surface adsorb in the H{sub 3} hollow site. • The preferred adsorption site is in contrary to the stacking order of bulk crystal. • The presence of hydrogen increases the adsorption energy of Si/C. • Hydrogen weakens the bonds between the adsorbed Si or C and the surface. • Carbon adsorbs on top of the surface carbon on the C-terminated surface. • With both C and H on Si-terminated surface the surface state vanishes. - Abstract: Density functional theory (DFT) study of adsorption of 0.25 monolayer of either Si or C on 4H-SiC{0001} surfaces is presented. The adsorption in high-symmetry sites on both Si- and C-terminated surfaces was examined and the influence of the preadsorbed 0.25 ML of hydrogen on the Si/C adsorption was considered. It was found out that for Si on C-terminated surface and C on Si-terminated the most favourable is threefolded adsorption site on both clean and H-precovered surface. This is contrary to the bulk crystal stacking order which would require adsorption on top of the topmost surface atom. In those cases, the presence of hydrogen weakens the bonding of the adsorbate. Carbon on the C-terminated surface, only binds on-top of the surface atom. The C−C bond-length is almost the same for the clean surface and for one with H and equals to ∼1.33 Å which is shorter by ∼0.2 than in diamond. The analysis of the electronic structure changes under adsorption is also presented.

  3. Sr-Al-Si co-segregated regions in eutectic Si phase of Sr-modified Al-10Si alloy.

    Science.gov (United States)

    Timpel, M; Wanderka, N; Schlesiger, R; Yamamoto, T; Isheim, D; Schmitz, G; Matsumura, S; Banhart, J

    2013-09-01

    The addition of 200 ppm strontium to an Al-10 wt% Si casting alloy changes the morphology of the eutectic silicon phase from coarse plate-like to fine fibrous networks. In order to clarify this modification mechanism the location of Sr within the eutectic Si phase has been investigated by a combination of high-resolution methods. Whereas three-dimensional atom probe tomography allows us to visualise the distribution of Sr on the atomic scale and to analyse its local enrichment, transmission electron microscopy yields information about the crystallographic nature of segregated regions. Segregations with two kinds of morphologies were found at the intersections of Si twin lamellae: Sr-Al-Si co-segregations of rod-like morphology and Al-rich regions of spherical morphology. Both are responsible for the formation of a high density of multiple twins and promote the anisotropic growth of the eutectic Si phase in specific crystallographic directions during solidification. The experimental findings are related to the previously postulated mechanism of "impurity induced twinning". Copyright © 2012 Elsevier B.V. All rights reserved.

  4. siMS Score: Simple Method for Quantifying Metabolic Syndrome

    OpenAIRE

    Soldatovic, Ivan; Vukovic, Rade; Culafic, Djordje; Gajic, Milan; Dimitrijevic-Sreckovic, Vesna

    2016-01-01

    Objective To evaluate siMS score and siMS risk score, novel continuous metabolic syndrome scores as methods for quantification of metabolic status and risk. Materials and Methods Developed siMS score was calculated using formula: siMS score = 2*Waist/Height + Gly/5.6 + Tg/1.7 + TAsystolic/130?HDL/1.02 or 1.28 (for male or female subjects, respectively). siMS risk score was calculated using formula: siMS risk score = siMS score * age/45 or 50 (for male or female subjects, respectively) * famil...

  5. Ultrathin SiO{sub 2} layer formed by the nitric acid oxidation of Si (NAOS) method to improve the thermal-SiO{sub 2}/Si interface for crystalline Si solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Taketoshi; Nakajima, Hiroki; Irishika, Daichi; Nonaka, Takaaki; Imamura, Kentaro; Kobayashi, Hikaru, E-mail: h.kobayashi@sanken.osaka-u.ac.jp

    2017-02-15

    Highlights: • The density of interface states at the SiO{sub 2}/Si interface is decreased by NAOS. • The minority carrier lifetime is increased by the NAOS treatment. • Great interfacial properties of the NAOS layer are kept after thermal oxidation. - Abstract: A combination of the nitric acid oxidation of Si (NAOS) method and post-thermal oxidation is found to efficiently passivate the SiO{sub 2}/n-Si(100) interface. Thermal oxidation at 925 °C and annealing at 450 °C in pure hydrogen atmosphere increases the minority carrier lifetime by three orders of magnitude, and it is attributed to elimination of Si dangling bond interface states. Fabrication of an ultrathin, i.e., 1.1 nm, NAOS SiO{sub 2} layer before thermal oxidation and H{sub 2} annealing further increases the minority carrier lifetime by 30% from 8.6 to 11.1 ms, and decreased the interface state density by 10% from 6.9 × 10{sup 9} to 6.3 × 10{sup 9}eV{sup −1} cm{sup −2}. After thermal oxidation at 800 °C, the SiO{sub 2} layer on the NAOS-SiO{sub 2}/Si(100) structure is 2.26 nm thick, i.e., 0.24 nm thicker than that on the Si(100) surface, while after thermal oxidation at 925 °C, it is 4.2 nm thick, i.e., 0.4 nm thinner than that on Si(100). The chemical stability results from the higher atomic density of a NAOS SiO{sub 2} layer than that of a thermal oxide layer as reported in Ref. [28] (Asuha et al., 2002). Higher minority carrier lifetime in the presence of the NAOS layer indicates that the NAOS-SiO{sub 2}/Si interface with a low interface state density is preserved after thermal oxidation, which supports out-diffusion oxidation mechanism, by which a thermal oxide layer is formed on the NAOS SiO{sub 2} layer.

  6. La normativa italiana sui contratti di lavoro a tempo determinato nel settore della scuola è contraria al diritto dell’Unione: la Corte di Giustizia UE apre al risarcimento per i docenti che abbiano svolto supplenze annuali per la copertura di posti vacanti

    Directory of Open Access Journals (Sweden)

    Arando Plaia

    2015-01-01

    Full Text Available La Corte di Giustizia UE con sentenza 26 novembre 2014, cause riunite C-22/13, C-61/13, C-62/13, C-63/13, C-418/13, Mascolo, ha ritenuto che la normativa europea sul lavoro a tempo determinato, applicabile anche al settore pubblico della scuola (casi Rosado Santana, Marrosu Sardino e Adelener, osta ad un sistema di assunzione per svolgere “supplenze annuali” nelle scuole pubbliche che non prevede almeno una delle seguenti “misure di prevenzione”: l’indicazione delle “ragioni oggettive” che giustificano il rinnovo dei contratti; la determinazione della “durata massima totale dei contratti” o del “numero dei loro rinnovi”, in assenza peraltro di una misura sanzionatoria proporzionata, effettiva e dissuasiva, da applicarsi in caso di utilizzo abusivo di successione di contratti a tempo determinato (clausola 5 dell’accordo quadro 18 marzo 1999 allegato dir. 1999/70/CE. Sebbene dunque il settore dell’insegnamento implichi inevitabilmente una certa “flessibilità”, e la normativa europea non enunci un obbligo generale degli Stati membri di prevedere la sanzione della trasformazione dei contratti di lavoro a tempo determinato in contratti a tempo indeterminato (CGUE 3 luglio 2014, Fiamingo, causa C-362/13, la normativa italiana non prevede misure atte a “prevenire” o “sanzionare” l’utilizzo abusivo di successione di contratti a tempo determinato. Questo (e non altro il principio di diritto affermato dalla Corte di giustizia: la sentenza ribadisce l’assenza di misure di prevenzione imposte dalla disciplina europea nonché di una sanzione risarcitoria rispetto al ricorso abusivo ai contratti a tempo determinato nel settore scolastico.

  7. Near-surface segregation in irradiated Ni3Si

    International Nuclear Information System (INIS)

    Wagner, W.; Rehn, L.E.; Wiedersich, H.

    1982-01-01

    The radiation-induced growth of Ni 3 Si films on the surfaces of Ni(Si) alloys containing = 3 Si phase has been observed. Post-irradiation depth profiling by Auger electron spectroscopy, as well as in situ analysis by high-resolution Rutherford backscattering spectrometry, reveals Si-enrichment at the surfaces of Ni(Si) alloys in excess of stoichiometric Ni 3 Si during irradiation. Thin, near-surface layers with silicon concentrations of 28 to 30 at.% are observed, and even higher Si enrichment is found in the first few atom layers. Transmission electron microscopy and selected area-electron diffraction were employed to characterize these Si-enriched layers. A complex, multiple-spot diffraction pattern is observed superposed on the diffraction pattern of ordered Ni 3 Si. The d-spacings obtained from the extra spots are consistent with those of the orthohexagonal intermetallic compound Ni 5 Si 2 . (author)

  8. FOCUS SULLA SENSIBILITÀ LINGUISTICA: LA TRADUZIONE COLLABORATIVA NELLA CLASSE DI LINGUA

    Directory of Open Access Journals (Sweden)

    Gioia Panzarella

    2017-03-01

    Full Text Available Può la traduzione facilitare la didattica delle lingue moderne? Questo articolo illustra i primi risultati di un progetto di ricerca in corso presso l’Università di Warwick, Regno Unito, (in collaborazione con l’Università di Monash, Australia che riguarda l’uso della traduzione collaborativa nell’insegnamento delle lingue a studenti universitari e a studenti Erasmus. Le autrici si sono concentrate sui vantaggi in termini di sensibilità linguistica e consapevolezza culturale derivanti da un particolare modello di traduzione collaborativa. Quando la proposta di “Collaborative Translation: A Model for Inclusion” si applica al particolare contesto della didattica delle lingue, infatti, l’insegnante e gli studenti esplorano insieme il processo di traduzione di un testo verso la lingua madre degli studenti. Il valore di questo approccio risiede nel privilegiare una messa in discussione della corrispondenza univoca tra due termini in due diverse lingue: l’insegnante è infatti un collaboratore della traduzione che agisce come facilitatore, chiedendo agli studenti-collaboratori di assumersi la responsabilità della traduzione. L’abilità linguistica in sé, di conseguenza, ha un ruolo secondario rispetto alla curiosità e alla riflessione linguistica nei confronti della propria lingua. I  workshop di inglese e di italiano sono stati rivolti rispettivamente a studenti principianti e a studenti avanzati. Focus on language sensitivity: collaborative translation in language class How can translation facilitate language learning? Reporting on the preliminary findings of an ongoing research project into the use of translation in language learning at the University of Warwick, UK (in collaboration with the University of Monash, Australia, the authors investigate the advantages of a specific translation model in terms of linguistic sensitivity and cultural awareness. The ‘Collaborative Translation: A Model for Inclusion’ prototype is

  9. Gate-stack engineering for self-organized Ge-dot/SiO2/SiGe-shell MOS capacitors

    Directory of Open Access Journals (Sweden)

    Wei-Ting eLai

    2016-02-01

    Full Text Available We report the first-of-its-kind, self-organized gate-stack heterostructure of Ge-dot/SiO2/SiGe-shell on Si fabricated in a single step through the selective oxidation of a SiGe nano-patterned pillar over a Si3N4 buffer layer on a Si substrate. Process-controlled tunability of the Ge-dot size (7.5−90 nm, the SiO2 thickness (3−4 nm, and as well the SiGe-shell thickness (2−15 nm has been demonstrated, enabling a practically-achievable core building block for Ge-based metal-oxide-semiconductor (MOS devices. Detailed morphologies, structural, and electrical interfacial properties of the SiO2/Ge-dot and SiO2/SiGe interfaces were assessed using transmission electron microscopy, energy dispersive x-ray spectroscopy, and temperature-dependent high/low-frequency capacitance-voltage measurements. Notably, NiGe/SiO2/SiGe and Al/SiO2/Ge-dot/SiO2/SiGe MOS capacitors exhibit low interface trap densities of as low as 3-5x10^11 cm^-2·eV^-1 and fixed charge densities of 1-5x10^11 cm^-2, suggesting good-quality SiO2/SiGe-shell and SiO2/Ge-dot interfaces. In addition, the advantage of having single-crystalline Si1-xGex shell (x > 0.5 in a compressive stress state in our self-aligned gate-stack heterostructure has great promise for possible SiGe (or Ge MOS nanoelectronic and nanophotonic applications.

  10. Metallization of ion beam synthesized Si/3C-SiC/Si layer systems by high-dose implantation of transition metal ions

    International Nuclear Information System (INIS)

    Lindner, J.K.N.; Wenzel, S.; Stritzker, B.

    2001-01-01

    The formation of metal silicide layers contacting an ion beam synthesized buried 3C-SiC layer in silicon by means of high-dose titanium and molybdenum implantations is reported. Two different strategies to form such contact layers are explored. The titanium implantation aims to convert the Si top layer of an epitaxial Si/SiC/Si layer sequence into TiSi 2 , while Mo implantations were performed directly into the SiC layer after selectively etching off all capping layers. Textured and high-temperature stable C54-TiSi 2 layers with small additions of more metal-rich silicides are obtained in the case of the Ti implantations. Mo implantations result in the formation of the high-temperature phase β-MoSi 2 , which also grows textured on the substrate. The formation of cavities in the silicon substrate at the lower SiC/Si interface due to the Si consumption by the growing silicide phase is observed in both cases. It probably constitutes a problem, occurring whenever thin SiC films on silicon have to be contacted by silicide forming metals independent of the deposition technique used. It is shown that this problem can be solved with ion beam synthesized contact layers by proper adjustment of the metal ion dose

  11. Comparison of interfaces for (Ba,Sr)TiO3 films deposited on Si and SiO2/Si substrates

    International Nuclear Information System (INIS)

    Suvorova, N.A.; Lopez, C.M.; Irene, E.A.; Suvorova, A.A.; Saunders, M.

    2004-01-01

    (Ba,Sr)TiO 3 (BST) thin films were deposited by ion sputtering on both bare and oxidized Si. Spectroscopic ellipsometry results have shown that a SiO 2 underlayer of nearly the same thickness (2.6 nm in average) is found at the Si interface for BST sputter depositions onto nominally bare Si, 1 nm SiO 2 on Si or 3.5 nm SiO 2 on Si. This result was confirmed by high-resolution electron microscopy analysis of the films, and it is believed to be due to simultaneous subcutaneous oxidation of Si and reaction of the BST layer with SiO 2 . Using the conductance method, capacitance-voltage measurements show a decrease in the interface trap density D it of an order of magnitude for oxidized Si substrates with a thicker SiO 2 underlayer. Further reduction of D it was achieved for the capacitors grown on oxidized Si and annealed in forming gas after metallization

  12. Comparison of interfaces for (Ba,Sr)TiO3 films deposited on Si and SiO2/Si substrates

    Science.gov (United States)

    Suvorova, N. A.; Lopez, C. M.; Irene, E. A.; Suvorova, A. A.; Saunders, M.

    2004-03-01

    (Ba,Sr)TiO3(BST) thin films were deposited by ion sputtering on both bare and oxidized Si. Spectroscopic ellipsometry results have shown that a SiO2 underlayer of nearly the same thickness (2.6 nm in average) is found at the Si interface for BST sputter depositions onto nominally bare Si, 1 nm SiO2 on Si or 3.5 nm SiO2 on Si. This result was confirmed by high-resolution electron microscopy analysis of the films, and it is believed to be due to simultaneous subcutaneous oxidation of Si and reaction of the BST layer with SiO2. Using the conductance method, capacitance-voltage measurements show a decrease in the interface trap density Dit of an order of magnitude for oxidized Si substrates with a thicker SiO2 underlayer. Further reduction of Dit was achieved for the capacitors grown on oxidized Si and annealed in forming gas after metallization.

  13. Exceptional cracking behavior in H-implanted Si/B-doped Si0.70Ge0.30/Si heterostructures

    Science.gov (United States)

    Chen, Da; Wang, Dadi; Chang, Yongwei; Li, Ya; Ding, Rui; Li, Jiurong; Chen, Xiao; Wang, Gang; Guo, Qinglei

    2018-01-01

    The cracking behavior in H-implanted Si/B-doped Si0.70Ge0.30/Si structures after thermal annealing was investigated. The crack formation position is found to closely correlate with the thickness of the buried Si0.70Ge0.30 layer. For H-implanted Si containing a buried 3-nm-thick B-doped Si0.70Ge0.30 layer, localized continuous cracking occurs at the interfaces on both sides of the Si0.70Ge0.30 interlayer. Once the thickness of the buried Si0.70Ge0.30 layer increases to 15 and 70 nm, however, a continuous sharp crack is individually observed along the interface between the Si substrate and the B-doped Si0.70Ge0.30 interlayer. We attribute this exceptional cracking behavior to the existence of shear stress on both sides of the buried Si0.70Ge0.30 layer and the subsequent trapping of hydrogen, which leads to a crack in a well-controlled manner. This work may pave the way for high-quality Si or SiGe membrane transfer in a feasible manner, thus expediting its potential applications to ultrathin silicon-on-insulator (SOI) or silicon-germanium-on-insulator (SGOI) production.

  14. Transformation mechanism of n-butyl terminated Si nanoparticles embedded into Si1-xCx nanocomposites mixed with Si nanoparticles and C atoms

    International Nuclear Information System (INIS)

    Shin, J.W.; Oh, D.H.; Kim, T.W.; Cho, W.J.

    2009-01-01

    Bright-field transmission electron microscopy (TEM) images, high-resolution TEM (HRTEM) images, and fast-Fourier transformed electron-diffraction patterns showed that n-butyl terminated Si nanoparticles were aggregated. The formation of Si 1-x C x nanocomposites was mixed with Si nanoparticles and C atoms embedded in a SiO 2 layer due to the diffusion of C atoms from n-butyl termination shells into aggregated Si nanoparticles. Atomic force microscopy (AFM) images showed that the Si 1-x C x nanocomposites mixed with Si nanoparticles and C atoms existed in almost all regions of the SiO 2 layer. The formation mechanism of Si nanoparticles and the transformation mechanism of n-butyl terminated Si nanoparticles embedded into Si 1-x C x nanocomposites mixed with Si nanoparticles and C atoms are described on the basis of the TEM, HRTEM, and AFM results. These results can help to improve the understanding of the formation mechanism of Si nanoparticles.

  15. Si/SiGe heterointerfaces in one-, two-, and three-dimensional nanostructures: their impact on SiGe light emission

    Science.gov (United States)

    Lockwood, David; Wu, Xiaohua; Baribeau, Jean-Marc; Mala, Selina; Wang, Xialou; Tsybeskov, Leonid

    2016-03-01

    Fast optical interconnects together with an associated light emitter that are both compatible with conventional Si-based complementary metal-oxide- semiconductor (CMOS) integrated circuit technology is an unavoidable requirement for the next-generation microprocessors and computers. Self-assembled Si/Si1-xGex nanostructures, which can emit light at wavelengths within the important optical communication wavelength range of 1.3 - 1.55 μm, are already compatible with standard CMOS practices. However, the expected long carrier radiative lifetimes observed to date in Si and Si/Si1-xGex nanostructures have prevented the attainment of efficient light-emitting devices including the desired lasers. Thus, the engineering of Si/Si1-xGex heterostructures having a controlled composition and sharp interfaces is crucial for producing the requisite fast and efficient photoluminescence (PL) at energies in the range 0.8-0.9 eV. In this paper we assess how the nature of the interfaces between SiGe nanostructures and Si in heterostructures strongly affects carrier mobility and recombination for physical confinement in three dimensions (corresponding to the case of quantum dots), two dimensions (corresponding to quantum wires), and one dimension (corresponding to quantum wells). The interface sharpness is influenced by many factors such as growth conditions, strain, and thermal processing, which in practice can make it difficult to attain the ideal structures required. This is certainly the case for nanostructure confinement in one dimension. However, we demonstrate that axial Si/Ge nanowire (NW) heterojunctions (HJs) with a Si/Ge NW diameter in the range 50 - 120 nm produce a clear PL signal associated with band-to-band electron-hole recombination at the NW HJ that is attributed to a specific interfacial SiGe alloy composition. For three-dimensional confinement, the experiments outlined here show that two quite different Si1-xGex nanostructures incorporated into a Si0.6Ge0.4 wavy

  16. Fabrication of highly oriented D03-Fe3Si nanocrystals by solid-state dewetting of Si ultrathin layer

    International Nuclear Information System (INIS)

    Naito, Muneyuki; Nakagawa, Tatsuhiko; Machida, Nobuya; Shigematsu, Toshihiko; Nakao, Motoi; Sudoh, Koichi

    2013-01-01

    In this paper, highly oriented nanocrystals of Fe 3 Si with a D0 3 structure are fabricated on SiO 2 using ultrathin Si on insulator substrate. First, (001) oriented Si nanocrystals are formed on the SiO 2 layer by solid state dewetting of the top Si layer. Then, Fe addition to the Si nanocrystals is performed by reactive deposition epitaxy and post-deposition annealing at 500 °C. The structures of the Fe–Si nanocrystals are analyzed by cross-sectional transmission electron microscopy and nanobeam electron diffraction. We observe that Fe 3 Si nanocrystals with D0 3 , B2, and A2 structures coexist on the 1-h post-annealed samples. Prolonged annealing at 500 °C is effective in obtaining Fe 3 Si nanocrystals with a D0 3 single phase, thereby promoting structural ordering in the nanocrystals. We discuss the formation process of the highly oriented D0 3 -Fe 3 Si nanocrystals on the basis of the atomistic structural information. - Highlights: • Highly oriented Fe–Si nanocrystals (NCs) are fabricated by reactive deposition. • Si NCs formed by solid state dewetting of Si thin layers are used as seed crystals. • The structures of Fe–Si NCs are analyzed by nanobeam electron diffraction. • Most of Fe–Si NCs possess the D0 3 structure after post-deposition annealing

  17. Effect of Si implantation on the microstructure of silicon nanocrystals and surrounding SiO2 layer

    International Nuclear Information System (INIS)

    Ross, G.G.; Smirani, R.; Levitcharsky, V.; Wang, Y.Q.; Veilleux, G.; Saint-Jacques, R.G.

    2005-01-01

    Si nanocrystals (Si-nc) embedded in a SiO 2 layer have been characterized by means of transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). For local Si concentration in excess 8 x 10 21 Si + /cm 3 , the size of the Si-nc was found to be ∼3 nm and comparatively homogeneous throughout the whole implanted layer. For local Si concentration in excess of ∼2.4 x 10 22 Si + /cm 3 , the Si-nc diameter ranges from ∼2 to ∼12 nm in the sample, the Si-nc in the middle region of the implanted layer being bigger than those near the surface and the bottom of the layer. Also, Si-nc are visible deeper than the implanted depth. Characterization by XPS shows that a large quantity of oxygen was depleted from the first ∼25 nm in this sample (also visible on TEM image) and most of the SiO 2 bonds have been replaced by Si-O bonds. Experimental and simulation results suggest that a local Si concentration in excess of ∼3 x 10 21 Si/cm 3 is required for the production of Si-nc

  18. Chemically activated graphene/porous Si@SiO{sub x} composite as anode for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Hua-Chao [College of Materials and Chemical Engineering, China Three Gorges University, 8 Daxue Road, Yichang, Hubei 443002 (China); Collaborative Innovation Center for Microgrid of New Energy, Hubei Province (China); Yang, Xue-Lin, E-mail: xlyang@ctgu.edu.cn [College of Materials and Chemical Engineering, China Three Gorges University, 8 Daxue Road, Yichang, Hubei 443002 (China); Collaborative Innovation Center for Microgrid of New Energy, Hubei Province (China); Zhang, Lu-Lu; Ni, Shi-Bing [College of Materials and Chemical Engineering, China Three Gorges University, 8 Daxue Road, Yichang, Hubei 443002 (China); Collaborative Innovation Center for Microgrid of New Energy, Hubei Province (China)

    2014-10-15

    Chemically activated graphene/porous Si@SiO{sub x} (CAG/Si@SiO{sub x}) composite has been synthesized via magnesiothemic reduction of mesoporous SiO{sub 2} (MCM-48) to porous Si@SiO{sub x} and dispersing in the suspension of chemically activated graphene oxide (CAGO) followed by thermal reduction. The porous Si@SiO{sub x} particles are well encapsulated in chemically activated graphene (CAG) matrix. The resulting CAG/Si@SiO{sub x} composite exhibits a high reversible capacity and excellent cycling stability up to 763 mAh g{sup −1} at a current density of 100 mA g{sup −1} after 50 cycles. The porous structure of CAG layer and Si@SiO{sub x} is beneficial to accommodate volume expansion of Si during discharge and charge process and the interconnected CAG improves the electronic conductivity of composite. - Highlights: • Chemically activated graphene encapsulated porous Si composite was prepared. • The graphene offers a continuous electrically conductive network. • The porous structure can accommodate volume expansion of Si-based materials. • The composite exhibits excellent lithium storage performance.

  19. Realization of Colored Multicrystalline Silicon Solar Cells with SiO2/SiNx:H Double Layer Antireflection Coatings

    Directory of Open Access Journals (Sweden)

    Minghua Li

    2013-01-01

    Full Text Available We presented a method to use SiO2/SiNx:H double layer antireflection coatings (DARC on acid textures to fabricate colored multicrystalline silicon (mc-Si solar cells. Firstly, we modeled the perceived colors and short-circuit current density (Jsc as a function of SiNx:H thickness for single layer SiNx:H, and as a function of SiO2 thickness for the case of SiO2/SiNx:H (DARC with fixed SiNx:H (refractive index n=2.1 at 633 nm, and thickness = 80 nm. The simulation results show that it is possible to achieve various colors by adjusting the thickness of SiO2 to avoid significant optical losses. Therefore, we carried out the experiments by using electron beam (e-beam evaporation to deposit a layer of SiO2 over the standard SiNx:H for 156×156 mm2 mc-Si solar cells which were fabricated by a conventional process. Semisphere reflectivity over 300 nm to 1100 nm and I-V measurements were performed for grey yellow, purple, deep blue, and green cells. The efficiency of colored SiO2/SiNx:H DARC cells is comparable to that of standard SiNx:H light blue cells, which shows the potential of colored cells in industrial applications.

  20. Subversion and reconstruction of the detective novel: a reading of ...

    African Journals Online (AJOL)

    Nella lettura che si fa del terzo romanzo poliziesco di Sciascia, lo si scompone per dimostrare come l'autore intenzionalmente sovverte, manipola e rielabora la tecnica e gli elementi che costituiscono il 'giallo' come genere. Nel contempo si cerca di decifrare la pletora di citazioni pittoriche e letterarie che s'intrecciano nella ...

  1. Simulations of Proton Implantation in Silicon Carbide (SiC)

    Science.gov (United States)

    2016-03-31

    Simulations of Proton Implantation in Silicon Carbide (SiC) Jonathan P. McCandless, Hailong Chen, Philip X.-L. Feng Electrical Engineering, Case...of implanting protons (hydrogen ions, H+) into SiC thin layers on silicon (Si) substrate, and explore the ion implantation conditions that are...relevant to experimental radiation of SiC layers. Keywords: silicon carbide (SiC); radiation effects; ion implantation ; proton; stopping and range of

  2. Synthesis of micro-sized interconnected Si-C composites

    Science.gov (United States)

    Wang, Donghai; Yi, Ran; Dai, Fang

    2016-02-23

    Embodiments provide a method of producing micro-sized Si--C composites or doped Si--C and Si alloy-C with interconnected nanoscle Si and C building blocks through converting commercially available SiO.sub.x (0

  3. SiC-Si as a support material for oxygen evolution electrode in PEM steam electrolysers

    DEFF Research Database (Denmark)

    Nikiforov, Aleksey; Tomás García, Antonio Luis; Petrushina, Irina

    2011-01-01

    The need of higher energy efficiency in hydrogen production has promoted the research on improved catalysts for water electrolysis. In this work, a novel supported catalyst for oxygen evolution electrodes was prepared and characterized with different techniques. IrO2 supported on a SiC/Si composite...

  4. Progressive degradation in a-Si: H/SiN thin film transistors

    NARCIS (Netherlands)

    Merticaru, A.R.; Mouthaan, A.J.; Kuper, F.G.

    2003-01-01

    In this paper we present the study of gate-stress induced degradation in a-Si:H/SiN TFTs. The drain current transient during gate bias stress (forward or reverse bias) and subsequent relaxation cannot be fitted with the models existent in the literature but it shows to be described by a progressive

  5. INCLUSIVE SYSTEMATICS FOR SI-28+SI-28 REACTIONS BETWEEN 20 AND 35 MEV PER NUCLEON

    NARCIS (Netherlands)

    BOX, PF; GRIFFIOEN, KA; DECOWSKI, P; BOOTSMA, T; GIERLIK, E; VANNIEUWENHUIZEN, GJ; TWENHOFEL, C; KAMERMANS, R; WILSCHUT, HW; GIORNI, A; MORAND, C; DEMEYER, A; GUINET, D

    Inclusive velocity spectra of heavy ions produced in the Si-28 + Si-28 reaction at 22, 26, 30, and 35 MeV per nucleon were measured and decomposed into peripheral and central components using an analytical moving-source parametrization. The persistence of incomplete fusion followed by evaporation

  6. Phenomenological inelastic constitutive equations for SiC and SiC fibers under irradiation

    International Nuclear Information System (INIS)

    El-Azab, A.; Ghoniem, N.M.

    1994-01-01

    Experimental data on irradiation-induced dimensional changes and creep in β-SiC and SiC fibers is analyzed, with the objective of studying the constitutive behavior of these materials under high-temperature irradiation. The data analysis includes empirical representation of irradiation-induced dimensional changes in SiC matrix and SiC fibers as function of time and irradiation temperature. The analysis also includes formulation of simple scaling laws to extrapolate the existing data to fusion conditions on the basis of the physical mechanisms of radiation effects on crystalline solids. Inelastic constitutive equations are then developed for SCS-6 SiC fibers, Nicalon fibers and CVD SiC. The effects of applied stress, temperature, and irradiation fields on the deformation behavior of this class of materials are simultaneously represented. Numerical results are presented for the relevant creep functions under the conditions of the fusion reactor (ARIES IV) first wall. The developed equations can be used in estimating the macro mechanical properties of SiC-SiC composite systems as well as in performing time-dependent micro mechanical analysis that is relevant to slow crack growth and fiber pull-out under fusion conditions

  7. NIMROD Simulations of the HIT-SI and HIT-SI3 Devices

    Science.gov (United States)

    Morgan, Kyle; Jarboe, Tom; Hossack, Aaron; Chandra, Rian; Everson, Chris

    2017-10-01

    The Helicity Injected Torus with Steady Inductive helicity injection (HIT-SI) experiment uses a set of inductively driven helicity injectors to apply non-axisymmetric current drive on the edge of the plasma, driving an axisymmetric spheromak equilibrium in a central confinement volume. Significant improvements have been made to extended MHD modeling of HIT-SI, with both the resolution of disagreement at high injector frequencies in HIT-SI in addition to successes with the new upgraded HIT-SI3 device. Previous numerical studies of HIT-SI, using a zero-beta eMHD model, focused on operations with a drive frequency of 14.5 kHz, and found reduced agreement with both the magnetic profile and current amplification at higher frequencies (30-70 kHz). HIT-SI3 has three helicity injectors which are able to operate with different mode structures of perturbations through the different relative temporal phasing of the injectors. Simulations that allow for pressure gradients have been performed in the parameter regimes of both devices using the NIMROD code and show improved agreement with experimental results, most notably capturing the observed Shafranov-shift due to increased beta observed at higher finj in HIT-SI and the variety of toroidal perturbation spectra available in HIT-SI3. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award Number DE-FG02- 96ER54361.

  8. Weld microstructure in cast AlSi9/SiC(p metal matrix composites

    Directory of Open Access Journals (Sweden)

    J. Wysocki

    2009-04-01

    Full Text Available Welded joint in cast AlSi9/SiC/20(p metal matrix composite by manual TIG arc welding using AlMg5 filler metal has been described inhis paper. Cooling curves have been stated, and the influence in distribution of reinforced particles on crystallization and weldmicrostructure. Welded joint mechanical properties have been determined: hardness and tensile.

  9. Atomic state and characterization of nitrogen at the SiC/SiO2 interface

    International Nuclear Information System (INIS)

    Xu, Y.; Garfunkel, E. L.; Zhu, X.; Lee, H. D.; Xu, C.; Shubeita, S. M.; Gustafsson, T.; Ahyi, A. C.; Sharma, Y.; Williams, J. R.; Lu, W.; Ceesay, S.; Tuttle, B. R.; Pantelides, S. T.; Wan, A.; Feldman, L. C.

    2014-01-01

    We report on the concentration, chemical bonding, and etching behavior of N at the SiC(0001)/SiO 2 interface using photoemission, ion scattering, and computational modeling. For standard NO processing of a SiC MOSFET, a sub-monolayer of nitrogen is found in a thin inter-layer between the substrate and the gate oxide (SiO 2 ). Photoemission shows one main nitrogen related core-level peak with two broad, higher energy satellites. Comparison to theory indicates that the main peak is assigned to nitrogen bound with three silicon neighbors, with second nearest neighbors including carbon, nitrogen, and oxygen atoms. Surprisingly, N remains at the surface after the oxide was completely etched by a buffered HF solution. This is in striking contrast to the behavior of Si(100) undergoing the same etching process. We conclude that N is bound directly to the substrate SiC, or incorporated within the first layers of SiC, as opposed to bonding within the oxide network. These observations provide insights into the chemistry and function of N as an interface passivating additive in SiC MOSFETs

  10. Atomization of U3Si2/U3Si for research reactor fuel

    International Nuclear Information System (INIS)

    Kuk, Il Hiun

    2004-01-01

    Instead of comminuting, U 3 Si 2 /U 3 Si powders are produced by atomizating directly from the molten alloys. Many benefits are introduced by applying the atomization technique: reduction of the process, homogeneous alloy composition within a particle and between particles, increase of the thermal conductivity and decrease of the chemical reactivity with aluminium due to particle's spherical shape. (author)

  11. Effects of dual-ion irradiation on the swelling of SiC/SiC composites

    International Nuclear Information System (INIS)

    Kishimoto, Hirotatsu; Kohyama, Akira; Ozawa, Kazumi; Kondo, Sosuke

    2005-01-01

    Silicon carbide (SiC) matrix composites reinforced by SiC fibers is a candidate structural material of fusion gas-cooled blanket system. From the viewpoint of material designs, it is important to investigate the swelling by irradiation, which results from the accumulation of displacement damages. In the fusion environment, (n, α) nuclear reactions are considered to produce helium gas in SiC. For the microstructural evolution, a dual-ion irradiation method is able to simulate the effects of helium. In the present research, 1.7 MeV tandem and 1 MeV single-end accelerators were used for Si self-ion irradiation and helium implantation, respectively. The average helium over displacement per atom (dpa) ratio in SiC was adjusted to 60 appm/dpa. The irradiation temperature ranged from room temperature to 1400degC. The irradiation-induced swelling was measured by the step height method. Helium that was implanted simultaneously with displacement damages in dual-ion irradiated SiC increased the swelling that was larger than that by single-ion irradiated SiC below 800degC. Since this increase was not observed above 1000degC, the interaction of helium and displacement damages was considered to change above 800degC. In this paper, the microstructural behavior and dimensional stability of SiC materials under the fusion relevant environment are discussed. (author)

  12. New evaluation method of crack growth in SiC/SiC composites using interface elements

    International Nuclear Information System (INIS)

    Serizawa, H.; Ando, M.; Lewinsohn, C.A.; Murakawa, H.

    2000-01-01

    Crack propagation behavior in SiC/SiC composites was analyzed using a new computer simulation method that included time-dependent interface elements. The simulation method was used to describe the time-dependent crack growth in SiC/SiC composites under four-point bending of single-edge-notched beam bend-bars. Two methods were used to simulate time-dependent crack growth in SiC/SiC composites due to fiber creep. In one method, the creep property was introduced into the interface elements by the general method of finite element method (FEM) analysis. In the second method, a new technique making the best use of the potential function was used to represent crack closure tractions due to creeping fibers. The stage-II slow crack growth of a general creep deformation was simulated by both methods. Additionally, stage-III crack growth and the transition from stage-II to stage-III could be simulated by the new method. The new method has the potential to completely simulate time-dependent crack growth behavior in SiC/SiC composites due to fiber creep

  13. Anomalous defect processes in Si implanted amorphous SiO2, II

    International Nuclear Information System (INIS)

    Fujita, Tetsuo; Fukui, Minoru; Okada, Syunji; Shimizu-Iwayama, Tsutomu; Hioki, Tatsumi; Itoh, Noriaki

    1994-01-01

    Aanomalous features of the defects in Si implanted amorphous SiO 2 are reported. The numbers of E 1 prime centers and B 2 centers are found to increase monotonically with implanted Si dose, in contrast to the saturating feature of these numbers in Ar implanted samples. Moreover, when H ions are implanted in amorphous SiO 2 predamaged by Si implantation, both of the density and the number of E 1 prime centers increase and they reach a constant value at a small H dose. We point out that these anomalies can be explained in terms of the difference in the cross-section for defect annihilation in the specimens implanted with Si ions and other ions, in accordance with the homogeneous model proposed by Devine and Golanski. We consider that the main mechanism of defect annihilation is the recombination of an E 1 prime center and an interstitial O, which is stabilized by an implanted Si, reducing the cross-section in Si-implanted specimens. ((orig.))

  14. Precipitation and strengthening phenomena in Al-Si-Ge and Al-Cu-Si-Ge alloys

    International Nuclear Information System (INIS)

    Mitlin, D.; Morris, J.W.; Dahmen, U.; Radmilovic, V.

    2000-01-01

    The objective of this work was to determine whether Al rich Al-Si-Ge and 2000 type Al-Cu-Si-Ge alloys have sufficient hardness to be useful for structural applications. It is shown that in Al-Si-Ge it is not possible to achieve satisfactory hardness through a conventional heat treatment. This result is explained in terms of sluggish precipitation of the diamond-cubic Si-Ge phase coupled with particle coarsening. However, Al-Cu-Si-Ge displayed a uniquely fast aging response, a high peak hardness and a good stability during prolonged aging. The high hardness of the Cu containing alloy is due to the dense and uniform distribution of fine θ' precipitates (metastable Al 2 Cu) which are heterogeneously nucleated on the Si-Ge particles. High resolution TEM demonstrated that in both alloys all the Si-Ge precipitates start out, and remain multiply twinned throughout the aging treatment. Since the twinned section of the precipitate does not maintain a low index interface with the matrix, the Si-Ge precipitates are equiaxed in morphology. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

  15. Computer aided cooling curve analysis for Al-5Si and Al-11Si alloys ...

    African Journals Online (AJOL)

    The effect of grain refiner, modifier, and combination of grain refiner cum modifier was studied on Al-5Si and Al-11Si alloys using computer aided cooling curve analysis. For combined grain refinement and modification effect, Al-Ti-B-Sr single master alloy was developed that acted as both grain refiner and modifier.

  16. C-V characterization of Schottky- and MIS-gate SiGe/Si HEMT structures

    International Nuclear Information System (INIS)

    Onojima, Norio; Kasamatsu, Akihumi; Hirose, Nobumitsu; Mimura, Takashi; Matsui, Toshiaki

    2008-01-01

    Electrical properties of Schottky- and metal-insulator-semiconductor (MIS)-gate SiGe/Si high electron mobility transistors (HEMTs) were investigated with capacitance-voltage (C-V) measurements. The MIS-gate HEMT structure was fabricated using a SiN gate insulator formed by catalytic chemical vapor deposition (Cat-CVD). The Cat-CVD SiN thin film (5 nm) was found to be an effective gate insulator with good gate controllability and dielectric properties. We previously investigated device characteristics of sub-100-nm-gate-length Schottky- and MIS-gate HEMTs, and reported that the MIS-gate device had larger maximum drain current density and transconductance (g m ) than the Schottky-gate device. The radio frequency (RF) measurement of the MIS-gate device, however, showed a relatively lower current gain cutoff frequency f T compared with that of the Schottky-gate device. In this study, C-V characterization of the MIS-gate HEMT structure demonstrated that two electron transport channels existed, one at the SiGe/Si buried channel and the other at the SiN/Si surface channel

  17. C-V characterization of Schottky- and MIS-gate SiGe/Si HEMT structures

    Energy Technology Data Exchange (ETDEWEB)

    Onojima, Norio [National Institute of Information and Communications Technology (NICT), Koganei, Tokyo 184-8795 (Japan)], E-mail: nonojima@nict.go.jp; Kasamatsu, Akihumi; Hirose, Nobumitsu [National Institute of Information and Communications Technology (NICT), Koganei, Tokyo 184-8795 (Japan); Mimura, Takashi [National Institute of Information and Communications Technology (NICT), Koganei, Tokyo 184-8795 (Japan); Fujitsu Laboratories Ltd., Atsugi, Kanagawa 243-0197 (Japan); Matsui, Toshiaki [National Institute of Information and Communications Technology (NICT), Koganei, Tokyo 184-8795 (Japan)

    2008-07-30

    Electrical properties of Schottky- and metal-insulator-semiconductor (MIS)-gate SiGe/Si high electron mobility transistors (HEMTs) were investigated with capacitance-voltage (C-V) measurements. The MIS-gate HEMT structure was fabricated using a SiN gate insulator formed by catalytic chemical vapor deposition (Cat-CVD). The Cat-CVD SiN thin film (5 nm) was found to be an effective gate insulator with good gate controllability and dielectric properties. We previously investigated device characteristics of sub-100-nm-gate-length Schottky- and MIS-gate HEMTs, and reported that the MIS-gate device had larger maximum drain current density and transconductance (g{sub m}) than the Schottky-gate device. The radio frequency (RF) measurement of the MIS-gate device, however, showed a relatively lower current gain cutoff frequency f{sub T} compared with that of the Schottky-gate device. In this study, C-V characterization of the MIS-gate HEMT structure demonstrated that two electron transport channels existed, one at the SiGe/Si buried channel and the other at the SiN/Si surface channel.

  18. Nanoscale Structuring by Misfit Dislocations in Si1-xGex/Si Epitaxial Systems

    DEFF Research Database (Denmark)

    Shiryaev, S.Y.; Jensen, Flemming; Hansen, J. Lundsgaard

    1997-01-01

    New capabilities of misfit dislocations for spatial manipulation of islands in Si1-xGex/Si heteroepitaxial systems have been elucidated. Formation of highly ordered Ge-island patterns on substrates prestructured by slip bands of misfit dislocations is revealed. The major sources leading to the or...

  19. Nonviral pulmonary delivery of siRNA.

    Science.gov (United States)

    Merkel, Olivia M; Kissel, Thomas

    2012-07-17

    RNA interference (RNAi) is an important part of the cell's defenses against viruses and other foreign genes. Moreover, the biotechnological exploitation of RNAi offers therapeutic potential for a range of diseases for which drugs are currently unavailable. Unfortunately, the small interfering RNAs (siRNAs) that are central to RNAi in the cytoplasm are readily degradable by ubiquitous nucleases, are inefficiently targeted to desired organs and cell types, and are excreted quickly upon systemic injection. As a result, local administration techniques have been favored over the past few years, resulting in great success in the treatment of viral infections and other respiratory disorders. Because there are several advantages of pulmonary delivery over systemic administration, two of the four siRNA drugs currently in phase II clinical trials are delivered intranasally or by inhalation. The air-blood barrier, however, has only limited permeability toward large, hydrophilic biopharmaceuticals such as nucleic acids; in addition, the lung imposes intrinsic hurdles to efficient siRNA delivery. Thus, appropriate formulations and delivery devices are very much needed. Although many different formulations have been optimized for in vitro siRNA delivery to lung cells, only a few have been reported successful in vivo. In this Account, we discuss both obstacles to pulmonary siRNA delivery and the success stories that have been achieved thus far. The optimal pulmonary delivery vehicle should be neither cytotoxic nor immunogenic, should protect the payload from degradation by nucleases during the delivery process, and should mediate the intracellular uptake of siRNA. Further requirements include the improvement of the pharmacokinetics and lung distribution profiles of siRNA, the extension of lung retention times (through reduced recognition by macrophages), and the incorporation of reversible or stimuli-responsive binding of siRNA to allow for efficient release of the siRNAs at the

  20. Compression of Fe-Si-H alloys

    Science.gov (United States)

    Tagawa, S.; Ohta, K.; Hirose, K.

    2014-12-01

    The light elements in the Earth's core have not been fully identified yet, but hydrogen is now collecting more attention in part because recent planet formation theory suggests that large amount of water should have been brought to the Earth during its formation (giant-impact stage). Nevertheless, the effect of hydrogen on the property of iron alloys is little known so far. The earlier experimental study by Hirao et al. [2004 GRL] examined the compression behavior of dhcp FeHx (x ≈ 1) and found that it becomes much stiffer than pure iron above 50 GPa, where magnetization disappears. Here we examined the solubility of hydrogen into iron-rich Fe-Si alloys and the compression behavior of dhcp Fe-Si-H alloy at room temperature. Fe+6.5wt.%Si or Fe+9wt.%Si foil was loaded into a diamond-anvil cell (DAC), and then liquid hydrogen was introduced at temperatures below 20 K. X-ray diffraction measurements at SPring-8 revealed the formation of a dhcp phase with or without thermal annealing by laser above 8.4 GPa. The concentration of hydrogen in such dhcp lattice was calculated following the formula reported by Fukai [1992]; y = 0.5 and 0.2 for Fe-6.5wt.%Si-H or Fe-9wt.%Si-H alloys, respectively when y is defined as Fe(1-x)SixHy. Unlike Fe-H alloy, hydrogen didn't fully occupy the octahedral sites even under hydrogen-saturated conditions in the case of Fe-Si-H system. Anomaly was observed in obtained pressure-volume curve around 44 Å3 of unit-cell volume for both Fe-6.5wt.%Si-H and Fe-9wt.%Si-H alloys, which may be related to the spin transition in the dhcp phase. They became slightly stiffer at higher pressures, but their compressibility was still similar to that of pure iron.

  1. Strain distribution in freestanding Si/Si{sub x}N{sub y} membranes studied by transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Hongye, E-mail: hongye18@mm.kyushu-u.ac.j [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Ikeda, Ken-ichi; Hata, Satoshi; Nakashima, Hideharu [Faculty of Engineering Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Wang, Dong; Nakashima, Hiroshi [Art, Science and Technology Center for Cooperative Research, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2010-09-30

    Strain was induced in a bridge-shaped freestanding Si membrane (FSSM) by depositing an amorphous Si{sub x}N{sub y} layer to surround the Si membrane. Convergent beam electron diffraction revealed that compressive strain is distributed uniformly along the horizontal direction in Si{sub x}N{sub y}-deposited FSSM. On the other hand, strain decreases to almost zero at the ends of the FSSM, where the Si{sub x}N{sub y} layer beneath the Si layer is replaced by a SiO{sub 2} buried oxide layer.

  2. The dependence of the interface and shape on the constrained growth of nc-Si in a-SiN sub x /a-Si:H/a-SiN sub x structures

    CERN Document Server

    Zhang Li; Wang Li; Li Wei; Xu Jun; Huang Xin Fan; Chen Kun Ji

    2002-01-01

    Size-controlled nanocrystalline silicon (nc-Si) has been prepared from a-SiN sub x /a-Si:H/a-SiN sub x ('a' standing for amorphous) structures by thermal annealing. Transmission electron microscope analyses show that the lateral size of the nc-Si is controlled by the annealing conditions and the a-Si sublayer thickness. The deviation of the nc-Si grain size distribution decreases with the a-Si sublayer thickness, so thinner a-Si sublayers are favourable for obtaining uniform nc-Si grains. In the a-Si:H (10 nm) sample annealed at 1000 deg. C for 30 min, an obvious bi-modal size distribution of nc-Si grains appears, but no obvious bi-modal size distribution is found in other samples with thinner a-Si:H sublayers. On the basis of the experimental results, we discuss the process of transition from the sphere-like shape to the disc-like shape in the growth model of the nc-Si crystallization. The critical thickness of the a-Si sublayer for the constrained crystallization can be determined by the present model. More...

  3. Strained Si engineering for nanoscale MOSFETs

    International Nuclear Information System (INIS)

    Park, Jea-Gun; Lee, Gon-Sub; Kim, Tae-Hyun; Hong, Seuck-Hoon; Kim, Seong-Je; Song, Jin-Hwan; Shim, Tae-Hun

    2006-01-01

    We have revealed a strain relaxation mechanism for strained Si grown on a relaxed SiGe-on-insulator structure fabricated by the bonding, dislocation sink, or condensation method. Strain relaxation for both the bonding and dislocation sink methods was achieved by grading the Ge concentration; in contrast, the relaxation for the condensation method was achieved through Ge atom condensation during oxidation. In addition, we estimated the surface roughness and threading-dislocation pit density for relaxed SiGe layer fabricated by the bonding, dislocation sink, or condensation method. The surface roughness and threading-dislocation pit density for the bonding, dislocation sink, and condensation methods were 2.45, 0.46, and 0.40 nm and 5.0 x 10 3 , 9 x 10 3 , and 0, respectively. In terms of quality and cost-effectiveness, the condensation method was superior to the bonding and dislocation sink methods for forming strained Si on a relaxed SiGe-on-insulator structure

  4. Carrier recombination in tailored multilayer Si/Si{sub 1−x}Ge{sub x} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Mala, S.A. [Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Tsybeskov, L., E-mail: tsybesko@njit.edu [Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Lockwood, D.J.; Wu, X.; Baribeau, J.-M. [National Research Council, Ottawa, ON, Canada KIA 0R6 (Canada)

    2014-11-15

    Photoluminescence (PL) measurements were performed in Si/Si{sub 1−x}Ge{sub x} nanostructures with a single Si{sub 0.92}Ge{sub 0.08} nanometer-thick layer incorporated into Si/Si{sub 0.6}Ge{sub 0.4} cluster multilayers. Under pulsed laser excitation, the PL decay associated with the Si{sub 0.92}Ge{sub 0.08} nano-layer is found to be nearly a 1000 times faster compared to that in Si/Si{sub 0.6}Ge{sub 0.4} cluster multilayers. A model considering Si/SiGe hetero-interface composition and explaining the fast and slow time-dependent recombination rates is proposed.

  5. Effect of hydrostatic pressure on photoluminescence spectra from structures with Si nanocrystals fabricated in SiO2 matrix

    International Nuclear Information System (INIS)

    Zhuravlev, K.S.; Tyschenko, I.E.; Vandyshev, E.N.; Bulytova, N.V.; Misiuk, A.; Rebohle, L.; Skorupa, W.

    2002-01-01

    The effect of hydrostatic pressure applied at high temperature on photoluminescence of Si-implanted SiO 2 films was studied. A 'blue'-shift of PL spectrum from the SiO 2 films implanted with Si + ions to total dose of 1.2x10 17 cm -2 with increase in hydrostatic pressure was observed. For the films implanted with Si + ions to a total dose of 4.8x10 16 cm -2 high temperature annealing under high hydrostatic pressure (12 kbar) causes a 'red'-shift of photoluminescence spectrum. The 'red' photoluminescence bands are attributed to Si nanocrystals while the 'blue' ones are related to Si nanocrystals of reduced size or chains of silicon atoms or Si-Si defects. A decrease in size of Si nanocluster occurs in result of the pressure-induced decrease in the diffusion of silicon atoms. (author)

  6. Positron annihilation in Si and Si-related materials in thermal equilibrium at high temperature

    International Nuclear Information System (INIS)

    Uedono, A.; Muramatsu, M.; Ubukata, T.; Tanino, H.; Shiraishi, T.; Tanigawa, S.; Takasu, S.

    2001-01-01

    Annihilation characteristics of positrons in the carbon/Si structure in thermal equilibrium at high temperature were studied using a monoenergetic positron beam. Doppler broadening spectra of the annihilation radiation were measured as a function of incident positron energy in the temperature range between 298 K and 1473 K. Above 1173 K, the value of S corresponding to the annihilation of positrons near the carbon/Si interface started to increase, which was attributed to the carbonization of Si and the introduction of open-space defects due to the diffusion of Si atoms toward the carbon layer. The behavior of Ps in a thermally grown SiO 2 film was also studied at 298-1523 K. (orig.)

  7. Mechanoactivation of chromium silicide formation in the SiC-Cr-Si system

    Directory of Open Access Journals (Sweden)

    Vlasova M.

    2002-01-01

    Full Text Available The processes of simultaneous grinding of the components of a SiC-Cr-Si mixture and further temperature treatment in the temperature range 1073-1793 K were studied by X-ray phase analysis, IR spectroscopy, electron microscopy, and X-ray microanalysis. It was established that, during grinding of the mixture, chromium silicides form. A temperature treatment completes the process. Silicide formation proceeds within the framework of the diffusion of silicon into chromium. In the presence of SiO2 in the mixture, silicide formation occurs also as a result of the reduction of silica by silicon and silicon carbide. The sintering of synthesized composite SiC-chromium silicides powders at a high temperature under a high pressure (T = 2073 K, P = 5 GPa is accompanied by the destruction of cc-SiC particles, the cc/3 transition in silicon carbide and deformation distortions of the lattices of chromium silicides.

  8. Joining of SiCf/SiC composites for thermonuclear fusion reactors

    International Nuclear Information System (INIS)

    Ferraris, M.; Badini, C.; Montorsi, M.; Appendino, P.; Scholz, H.W.

    1994-01-01

    Due to their favourable radiological behaviour, SiC f /SiC composites are promising structural materials for future use in fusion reactors. A problem to cope with is the joining of the ceramic composite material (CMC) to itself for more complex structures. Maintenance concepts for a reactor made of SiC f /SiC will demand a method of joining. The joining agents should comply with the low-activation approach of the base material. With the acceptable elements Si and Mg, sandwich structures of composite/metal/composite were prepared in Ar atmosphere at temperatures just above the melting points of the metals. Another promising route is the use of joining agents of boro-silicate glasses: their composition can be tailored to obtain softening temperatures of interest for fusion applications. The glassy joint can be easily ceramised to improve thermomechanical properties. The joining interfaces were investigated by SEM-EDS, XRD and mechanical tests. ((orig.))

  9. Formation of permeation barriers on ceramic SiC/SiC composites

    International Nuclear Information System (INIS)

    Racault, C.; Fenici, P.

    1996-01-01

    The effectiveness as permeation barriers of the following CVD and PVD (sputtering) coatings has been investigated: TiC+Al 2 O 3 (CVD), SiC(CVD), SiO 2 (CVD), TiN(CVD), TiN(CVD)+TiN(PVD) and SiC(CVD)+Al 2 O 3 (PVD). The substrate material was a SiC/SiC composite, proposed as low activation structural material for fusion applications. Permeation measurements were performed in the temperature range 300-750 K using deuterium at pressures in the range 0.5-150 kPa. A linear dependence of permeation rate on pressure was measured. The efficiency of the coatings as deuterium permeation barriers is discussed in terms of coating microstructure. The best result was obtained with a bilayer of TiN(CVD) (15 μm) +TiN(PVD) (8 μm). (orig.)

  10. On the compliant behaviour of free-standing Si nanostructures on Si(001) for Ge nanoheteroepitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Kozlowski, Grzegorz

    2012-04-24

    Selective chemical vapor deposition Ge heteroepitaxy approaches for high quality Ge nanostructure growth with reasonable thermal budget must be developed for local Ge photonic module integration. A promising vision is offered by the compliant substrate effects within nanometer scale Ge/Si heteroepitaxial structures. Here, in contrast to the classical Ge deposition on bulk Si substrates, the thermal and lattice mismatch strain energy accumulated in the Ge epilayer is partially shifted to the free-standing Si nanostructure. This strain partitioning phenomenon is at the very heart of the nanoheteroepitaxy theory (NHE) and, if strain energy levels are correctly balanced, offers the vision to grow defect-free nanostructures of lattice mismatched semiconductors on Si. In case of the Ge/Si heterosystem with a lattice mismatch of 4.2%, the strain partitioning phenomenon is expected to be triggered when free-standing Si nanopillars with the width of 50 nm and below are used. In order to experimentally verify NHE with its compliant substrate effects, a set of free-standing Ge/Si nanostructures with diameter ranging from 150 to 50 nm were fabricated and investigated. The main limitation corresponds to a simultaneous detection of (a) the strain partitioning phenomenon between Ge and Si and (b) the absence of defects on the nano-scale. In this respect, synchrotron-based grazing incidence X-ray diffraction was applied to study the epitaxial relationship, defect and strain characteristics with high resolution and sensitivity in a non-destructive way. Raman spectroscopy supported by finite element method calculations were used to investigate the strain distribution within a single Ge/Si nanostructure. Special focus was devoted to transmission electron microscopy to determine the quality of the Ge epilayer. It was found, that although high quality Ge nanoclusters can be achieved by thermal annealing on Si pillars bigger than 50 nm in width, no proof of strain partitioning

  11. Geometric structure of thin SiO xN y films on Si(100)

    Science.gov (United States)

    Behrens, K.-M.; Klinkenberg, E.-D.; Finster, J.; Meiwes-Broer, K.-H.

    1998-05-01

    Thin films of amorphous stoichometric SiO xN y are deposited on radiation-heated Si(100) by rapid thermal low-pressure chemical vapour deposition. We studied the whole range of possible compositions. In order to determine the geometric structure, we used EXAFS and photoelectron spectroscopy. Tetrahedrons constitute the short-range units with a central Si atom connected to N and O. The distribution of the possible tetrahedrons can be described by a mixture of the Random Bonding Model and the Random Mixture Model. For low oxygen contents x/( x+ y)≤0.3, the geometric structure of the film is almost the structure of a-Si 3N 4, with the oxygen preferably on top of Si-N 3 triangles. Higher oxygen contents induce changes in the bond lengths, bond angles and coordination numbers.

  12. Polarized micro-Raman scattering characterization of Mg2Si nanolayers in (001) Si matrix

    International Nuclear Information System (INIS)

    Zlateva, G; Atanassov, A; Baleva, M; Nikolova, L; Abrashev, M V

    2007-01-01

    An orientational growth of the Mg 2 Si lattice relative to the Si lattice is considered assuming minimum mismatch of their lattice parameters. The Raman scattering cross-sections are calculated for the four possible orientations of the Mg 2 Si lattice positioned in this way. The integral intensity ratios for the F 2g mode of Mg 2 Si in different polarization configurations, obtained from the experimental spectra, are compared with the calculated ratios. It is found that the Mg 2 Si nanolayer's morphology is sensitive to the implantation energy, which determines both the peak Mg concentration in the initial implantation profile and its position in the sample depth. At a peak concentration of the order of the stoichiometric concentration, the layers are highly oriented. When the peak concentration is higher and the peak is placed closer to the surface, the layers are polycrystalline

  13. Photoemission study on electrical dipole at SiO_2/Si and HfO_2/SiO_2 interfaces

    International Nuclear Information System (INIS)

    Fujimura, Nobuyuki; Ohta, Akio; Ikeda, Mitsuhisa; Makihara, Katsunori; Miyazaki, Seiichi

    2017-01-01

    Electrical dipole at SiO_2/Si and HfO_2/SiO_2 interfaces have been investigated by X-ray photoelectron spectroscopy (XPS) under monochromatized Al Kα radiation. From the analysis of the cut-off energy for secondary photoelectrons measured at each thinning step of a dielectric layer by wet-chemical etching, an abrupt potential change caused by electrical dipole at SiO_2/Si and HfO_2/SiO_2 interfaces has been clearly detected. Al-gate MOS capacitors with thermally-grown SiO_2 and a HfO_2/SiO_2 dielectric stack were fabricated to evaluate the Al work function from the flat band voltage shift of capacitance-voltage (C-V) characteristics. Comparing the results of XPS and C-V measurements, we have verified that electrical dipole formed at the interface can be directly measured by photoemission measurements. (author)

  14. Elevated Temperature Properties of Commercially Available NITE-SiC/SiC Composites

    International Nuclear Information System (INIS)

    Choi, Y.B.; Hinoki, T.; Kohyama, A.

    2007-01-01

    Full text of publication follows: Continuous fiber-reinforced ceramic matrix composites (CMCs) have been expected as a new type of material having high fracture resistance up to a high temperature. In recent years, there have been extensive efforts in our research group to develop high performance SiC/SiC composites for energy applications, where improvements in mechanical properties and damage resistance by innovative new fabrication process with emphasis on interface improvement have been greatly accomplished. One of the most outstanding accomplishments is the Nano-powder Infiltration and Transient Eutectic (NITE) process using PyC coated Tyranno-SA fibers. For making SiC/SiC composites more attractive and competitive for high temperature structural components and for other industrial applications, one of the key issues is to demonstrate its reliability and safety under severe environments. Also to demonstrate the potential to produce SiC/SiC by NITE process from large scale production line at industries is very important. This paper provides fundamental database of mechanical properties and microstructure of Cera-NITE, the trade name of NITE-SiC/SiC composites. The mechanical properties were evaluated by uni-axial tensile test from room temperature to high temperatures. The tensile properties, including elastic modulus, PLS and ultimate tensile strength, are superior to those of other conventional SiC/SiC composites. The macroscopic observation of Cera-NITE indicated high density as planned with almost no-porosity and cracks. Furthermore, Cera-NITE showed outstanding microstructural uniformity. The characteristic variation coming from the sampling location was hardly observed.. Further information about database of properties and microstructure at evaluated temperature will be provided. (authors)

  15. Microhardness evaluation alloys Hf-Si-B; Avaliacao de microdureza de ligas Hf-Si-B

    Energy Technology Data Exchange (ETDEWEB)

    Gigolotti, Joao Carlos Janio; Costa, Eliane Fernandes Brasil [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Nunes, Carlos Angelo; Rocha, Elisa Gombio; Coelho, Gilberto Carvalho, E-mail: carlosjanio@uol.com.br, E-mail: eliane-costabrasi@hotmail.com, E-mail: cnunes@demar.eel.usp.br, E-mail: elisarocha@alunos.eel.usp.br, E-mail: coelho@demar.eel.usp.br [Universidade de Sao Paulo (USP), Lorena, SP (Brazil)

    2014-08-15

    The technological advance has generated increasing demand for materials that can be used under high temperature, what includes intermetallic MR-Si-B (MR = refractory metal) alloys with multiphase structures, that can also be applied in oxide environments. Thus, this work had for objective the micro hardness study of the Hf-Si-B system alloys, heat treated at 1600 deg C, in the Hf rich region. Hf-Si-B alloys had been produced with blades of Hf (min. 99.8%), Si (min. 99.998%) and B (min. 99.5%), in the voltaic arc furnace and heat treated at 1600 deg C under argon atmosphere. The relationship of the phases had been previously identified by X-ray diffraction and contrast in backscattered electron imaging mode. The alloys had their hardness analyzed by method Vickers (micro hardness) with load of 0.05 kgf and 0.2 kgf and application time of 20 s. The results, obtained from the arithmetic mean of measurements for each alloy on the heterogeneous region, showed a mean hardness of 11.08 GPA, with small coefficient of variation of 3.8%. The borides HfB2 (19.34 GPa) e HfB - 11.76 GPa, showed the hardness higher than the silicides Hf2Si (8.57 GPa), Hf5Si3 (9.63 GPa), Hf3Si2 (11.66 GPa), Hf5Si4 (10.00 GPa), HfSi (10.02 GPa) e HfSi2 (8.61 GPa). (author)

  16. A TEM study of strained SiGe/Si and related heteroepitaxial structures

    International Nuclear Information System (INIS)

    Benedetti, Alessandro

    2002-01-01

    The role of SiGe/Si heterostructures and related materials has become increasingly important within the last few decades. In order to increase the scale of integration, however, devices with active elements not larger than few tens of nanometer have been recently introduced. There is, therefore, a strong need for an analytical technique capable of giving information about submicron-sized components. An investigation on a nanometre scale can be performed by the combination of a fully equipped Transmission Electron Microscope (TEM) with a Field Emission Gun (PEG) electron source, which enables one to use a wide range of analytical techniques with an electron probe as small as 0.5 nm. In this work, two different types of SiGe/Si-based devices were investigated. Strained-Si n-channel MOSFETs. The use of Strained-Si n-channel grown on SiGe should improve both carrier mobility and transconductance with respect to conventional MOSFETs. Materials analysed in this work showed an extremely high transconductance but a rather low mobility. In order to relate their microstructural properties to their electrical performance, as well as to improve the device design, a full quantitative and qualitative structural characterisation was performed. SiGe Multiple Quantum Wells (MQW) IR detectors Light detection is achieved by collecting the photogenerated carriers, injected from the SiGe QWs layers into the Si substrate. A key factor is the Ge profile across a single QW, since it governs the band structure and therefore the device performances. Four different TEM techniques were used to determine the Ge distribution across a single well, showing an overall good agreement among the results. The Ge profiles broadening, consistent with data available in literature, was successfully explained and theoretically predicted by the combined effect of Ge segregation and gas dwell times within the reactor. (author)

  17. Deposition of O atomic layers on Si(100) substrates for epitaxial Si-O superlattices: investigation of the surface chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Jayachandran, Suseendran, E-mail: suseendran.jayachandran@imec.be [KU Leuven, Department of Metallurgy and Materials, Castle Arenberg 44, B-3001 Leuven (Belgium); IMEC, Kapeldreef 75, 3001 Leuven (Belgium); Delabie, Annelies; Billen, Arne [KU Leuven, Department of Chemistry, Celestijnenlaan 200F, B-3001 Leuven (Belgium); IMEC, Kapeldreef 75, 3001 Leuven (Belgium); Dekkers, Harold; Douhard, Bastien; Conard, Thierry; Meersschaut, Johan; Caymax, Matty [IMEC, Kapeldreef 75, 3001 Leuven (Belgium); Vandervorst, Wilfried [KU Leuven, Department of Physics and Astronomy, Celestijnenlaan 200D, B-3001 Leuven (Belgium); IMEC, Kapeldreef 75, 3001 Leuven (Belgium); Heyns, Marc [KU Leuven, Department of Metallurgy and Materials, Castle Arenberg 44, B-3001 Leuven (Belgium); IMEC, Kapeldreef 75, 3001 Leuven (Belgium)

    2015-01-01

    Highlights: • Atomic layer is deposited by O{sub 3} chemisorption reaction on H-terminated Si(100). • O-content has critical impact on the epitaxial thickness of the above-deposited Si. • Oxygen atoms at dimer/back bond configurations enable epitaxial Si on O atomic layer. • Oxygen atoms at hydroxyl and more back bonds, disable epitaxial Si on O atomic layer. - Abstract: Epitaxial Si-O superlattices consist of alternating periods of crystalline Si layers and atomic layers of oxygen (O) with interesting electronic and optical properties. To understand the fundamentals of Si epitaxy on O atomic layers, we investigate the O surface species that can allow epitaxial Si chemical vapor deposition using silane. The surface reaction of ozone on H-terminated Si(100) is used for the O deposition. The oxygen content is controlled precisely at and near the atomic layer level and has a critical impact on the subsequent Si deposition. There exists only a small window of O-contents, i.e. 0.7–0.9 atomic layers, for which the epitaxial deposition of Si can be realized. At these low O-contents, the O atoms are incorporated in the Si-Si dimers or back bonds (-OSiH), with the surface Si atoms mainly in the 1+ oxidation state, as indicated by infrared spectroscopy. This surface enables epitaxial seeding of Si. For O-contents higher than one atomic layer, the additional O atoms are incorporated in the Si-Si back bonds as well as in the Si-H bonds, where hydroxyl groups (-Si-OH) are created. In this case, the Si deposition thereon becomes completely amorphous.

  18. Doutorado-sanduíche em enfermagem: relato de experiência Doctorado sándwich en enfermería: relato de experiencia Sandwich doctoral program in nursing: an experience report

    Directory of Open Access Journals (Sweden)

    Rosane Arruda Dantas

    2009-06-01

    Full Text Available Relato de experiência acerca de estágio de doutorando-sanduíche realizado com bolsa da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, durante o período de outubro de 2005 a janeiro de 2006, na Faculdade de Enfermagem de D. Ana Guedes, no Porto, em Portugal, instituição já visitada na graduação. Tive a oportunidade de replicar a metodologia de parte da dissertação com crianças portuguesas. Isso permitiu estudo comparativo entre duas culturas que guardam afinidades, mas têm características distintas. Além disso, ministrei aulas, participei de cursos e seminários e aprofundei os conhecimentos acerca da Teoria da Universalidade e Diversidade do Cuidado Cultural. Considero que esta experiência é um estímulo para a garantia da autonomia do enfermeiro na assistência de enfermagem, como pesquisador e docente, ampliando conhecimentos e os inserindo no processo de cuidado. Ademais, influencia positivamente no amadurecimento psicológico, cultural e social do doutorando.Relato de experiencia acerca de pasantía de doctorado sándwich realizado con suporte financiero de la Coordinación de Mejora del Personal del Nivel Superior, durante el período de octubre de 2005 a enero de 2006, en la Facultad de Enfermería de D. Ana Guedes, en Porto, Portugal, institución ya visitada durante la graduación. Tuve la oportunidad de replicar la metodología de parte de la disertación junto a niños portugueses. Esto permitió un estudio comparativo entre dos culturas que guardan afinidades, pero tienen características distintas. Además, ministré clases, participé de cursos y seminarios y me profundicé en los conocimientos acerca de la Teoría de la Universalidad y Diversidad del Cuidado Cultural. Considero que esta experiencia es un estímulo para la garantía de la autonomía del enfermero en la atención de enfermería, como investigadora y docente, ampliando conocimientos e insertándolos en el proceso de cuidado. Adem

  19. Variations autour de la tâche dans l'enseignement / apprentissage des langues aujourd'hui What kind of tasks are used for L2 teaching and learning today?

    Directory of Open Access Journals (Sweden)

    Elke Nissen

    2011-10-01

    Full Text Available Cet article se donne pour objectif d'identifier les types de tâches, et leurs dénominateurs communs, qui sont présentés aujourd'hui – où "l'approche par les tâches" est soutenue par le Conseil de l'Europe – aux apprenants. Il analyse pour cela les articles issus de deux numéros de revues et un ouvrage collectif récents. Il apparaît que la grande majorité des scénarios pédagogiques s'y inscrit dans la perspective actionnelle... du moins d'après la déclaration des auteurs, car leur définition de ce qu'est une tâche ne correspond pas toujours à celle du CECR. Pour le public visé, étudiants ou professionnels, on propose le plus souvent des mono-tâches, mais également des projets, ou encore des simulations avec un enchaînement de plusieurs tâches. Elles s'inscrivent généralement dans la (future réalité sociale des apprenants, mais certaines laissent également la place à des thèmes artistiques ou (interculturels. Contrairement à ce que l'on aurait pu attendre dans une démarche qui responsabilise l'apprenant, le recours à Internet n'est pas toujours systématique.At a time when action- and task-based learning is sustained by the European Council, this paper explores which types of tasks are given to second language learners today and what aspects these tasks have in common. The paper analyses two recent issues of scientific journals and one collective book. The analysis shows that the majority of pedagogical scenarios described in these texts claim to adopt an action- and task-based approach. However, in reality the way they define a task does not always correspond to the definition given by the European Framework of Reference for Languages. The described tasks are exclusively dedicated to higher and professional education; they are mostly single tasks, but they can also be projects and simulations including several successive tasks. They generally correspond to the learners' (future reality, with themes that are

  20. Approche multidimensionnelle de la difficulté objective dans une tâche d’anticipation coï ncidence Multidimensional approach of objective difficulty in an aiming task

    Directory of Open Access Journals (Sweden)

    P. Deneuve

    2010-09-01

    Full Text Available

     

    Cet article a pour objet de proposer une nouvelle procédure pour classer les tâches motrices à caractère informationnel à partir d’une approche multidimensionnelle de la difficulté. L’expérimentation a consisté à faire passer des tests de pointage à 345 sujets sur cibles mobiles créées et gérées par ordinateur. Les paramètres des cibles ont été choisis pour leur indépendance et la possibilité de les positionner sur des échelles numériques. Trois descripteurs ont été retenus : la vitesse de déplacement, la surface de la cible et l’incertitude spatiale. La performance ne semblant pas être la seule variable dépendante résumant la difficulté, il lui a été adjoint trois autres variables : les tentatives, le temps de réaction et le temps moteur. En utilisant des outils statistiques permettant des analyses de données multidimensionnelles (CAH, AFC, il a été possible soit d’agréger des tâches aux profils identiques soit de les différencier en fonction du poids de chaque descripteur sur les variables dépendantes. Surtout, il est envisageable de préciser l’apport de chaque variable dans la définition de la difficulté que se donne a posteriori le chercheur.
    PALABRAS CLAVE: Difficulté, traitement de l’information, tâche motrice, classification, analyse de données.

    This article deals with a new method to classify informational motor tasks, through a multidimensional approach of difficulty. The following experiment is used: 345 subjects are asked to point at computer-managed mobile targets. The 3 selected target parameters are: velocity, area and spatial uncertainty. Independence and numerical scalability are the reasons for this choice. As performance does not sump up difficulty, other dependent variables have been added: number of attempts, reaction time and motor time. The use of