bluuebunny/crossref_metadata_2025 huggingface dataset:
Questions de langage: Questions d'identité?
Authors: Hennuy Jean-Frédéric
Published: April 2011

Cet article explore la problématique des gros mots en tant qu'éléments constitutifs de l'identité française. En effet, en France, être capable de bien formuler un gros mot, une insulte ou une injure est considéré comme une forme de spiritualité et peut-être même d'art. Ainsi, afin de comprendre le rôle et la place que jouent les gros mots dans l'affirmation de l'identité française il est nécessaire de revisiter leurs définitions, leurs fonctions au regard de certaines notions telles que celles de liberté, égalité et fraternité. Et de cette manière, on verra que dans la culture française l'utilisation des gros mots s'étend bien au-delà de la simple transgression langagière.
Écrire au centre de soi-même: Le récit identitaire dans l'œuvre romanesque d'Abla Farhoud
Authors: Maddox Kelly-Anne
Published: April 2011

Dans l'œuvre romanesque d'Abla Farhoud, l'écriture est inextricablement liée à la problématique identitaire et ses ouvrages sont peuplés de nombreux écrivains. La création littéraire chez elle s'insère dans le cadre de relations familiales tendues, relations qui mènent les personnages à une remise en question de leur vision du monde et de leur identité. Cette crise plonge l'écrivain farhoudien dans une solitude intense et dans un vide qui l'obligent à confronter la vérité de son moi lui permettant par la suite d'écrire, comme le dit Farhoud, "au centre de soi-même." L'écriture finit par offrir la possibilité de surmonter l'aliénation et la solitude inhérentes à l'existence des personnages farhoudiens une fois qu'ils arrivent à se voir comme narrateurs de leur propre récit. La prise en charge de la narration permet aux personnages de rejoindre le monde et d'atteindre l'autre en partageant leur écriture dans le cadre d'une relation féconde entre narrateur et narrataire.
L'Ouest canadien: Écriture d'une francophonie minoritaire
Authors: Rinne Marie-Noëlle , Gafaïti Hafid
Published: April 2011

Cet article cherche à comprendre les éléments distinctifs qui donnent aux écrits de l'Ouest canadien leur particularité, leur unicité. Une ébauche se dresse à partir de l'étude de nombreuses nouvelles et romans, faisant appel à des anthologies de la "Prairie" comme à des auteurs plus connus, tels Nancy Huston, J. R. Léveillé ou Simone Chaput. L'article explore la notion d'espace en tant qu'élément structural, le concept d'errance à mettre en parallèle avec la nature minoritaire de cette francophonie, le recours au fantastique ainsi qu'au texte concis et, enfin, la récurrence de personnages archétypiques, à savoir la "Ouesterneuse" et le Métis ou la Métisse.
De Deuil à mélancolie: Regard de Gide sur une Afrique orientalisée dans Voyage au Congo
Authors: Smith Lise-Hélène
Published: April 2011

La relecture des carnets de route, Voyage au Congo , à travers un filtre freudien révèle toute l'ambivalence d'André Gide envers aussi bien l'espace africain que français. L'Afrique que Gide dépeint est un espace qui sans cesse échappe à toute forme de représentation et au sein duquel il s'efforce de fixer l'idée de l'Afrique qu'il cherche en vain à capturer. Déployant les tropes freudiens du deuil et par extension de la mélancolie, Gide cherche à attacher son moi dans le paysage africain pour remplacer l'objet de la perte: le sentiment d'appartenance à la France. Échouant dans son entreprise de deuil qui nécessite l'oubli, Gide implante alors un discours orientaliste sur le site africain afin de fixer cette Afrique qui ne se construit que comme espace vide. Ne se réconciliant pas avec son sentiment de perte, Gide sombre définitivement dans la mélancolie. Son voyage en Afrique ne fera que renforcer son aliénation.
Entre désécriture et oralité feinte: En attendant le vote des bêtes sauvages ou la rhétorique de l'instabilité
Authors: Diakité Boubakary
Published: April 2011

Ahmadou Kourouma est-il véritablement un écrivain créateur? Est-il simplement un habile traducteur en français de formules et formes littéraires empruntées à ses sources ethniques malinkés? Contrairement aux approches selon lesquelles Kourouma excelle dans la reproduction d'oeuvres empruntées à l'oralité, il faut affirmer que son génie transcende la traduction de la tradition. En réalité, l'écriture d' En attendant le vote des bêtes sauvages s'appuie sur une technique à cheval entre la désécriture et "l'oralité feinte." Conscient de la précarité et de l'instabilité des cultures africaines postcoloniales, Kourouma adopte une écriture fondée sur la contradiction de formes et le conflit de genres et modèles narratifs. Faisant éclater les mécanismes de l'écriture, il trahit les modèles traditionnels et occidentaux pour délivrer un roman instable où narrateurs et personnages évoluent dans une duplicité créatrice.
Jeux de miroirs dans Toto le héros de Jaco Van Dormael
Authors: Vanbaelen Sylvie
Published: April 2011

Cet article explore les multiples jeux de miroirs dans le film Toto le héros (1991) du réalisateur belge Jaco Van Dormael pour les rattacher à la problématique majeure au cœur de l'œuvre, la quête de l'identité. Thomas, le protagoniste du film, est un personnage fragmenté convaincu d'avoir raté sa vie et qui se cherche toujours ailleurs (dans les miroirs, les doubles, les héros imaginaires). De même, le film, Toto le héros , se présente sous la forme de fragments à assembler comme ceux d'un puzzle et doit sa cohésion aux associations d'images, répétitions de motifs, analogies et rimes, créant d'hallucinants jeux de miroirs.
Rhétorique de l'exemple et réception chez Kesso Barry et Hampâté Bâ
Authors: Sankara Edgard
Published: April 2011

Cet article analyse la rhétorique de l'exemple et sa réception chez deux autobiographes francophones africains. À travers une lecture croisée de Kesso, Princesse peuhle de Kesso Barry et Amkoullel, l'enfant peul d'Hampâté Bâ notre étude démontre deux rhétoriques de l'exemple divergentes: l'une contradictoire et à allocutaires multiples (Barry) et l'autre cohérente et focalisée sur un allocutaire unique non-Africain (Bâ). Il en ressort que le couplage rhétorique et réception problématisent l'écriture de l'autobiographie africaine dont la pertinence rhétorique fluctue au gré des allocutaires visés. Le degré de focalisation sur la colonisation dans ces deux autobiographies affecte également la construction de cette rhétorique.
Albert Camus, l'Algérien: In Memoriam
Authors: Toumi Alek Baylee
Published: April 2011

Condamné par les Français ultras, les sartriens et les Algériens de la tendance islamo-baathiste, le 4 janvier 1960, Albert Camus s'en allait un peu. Dans cet article, pour réhabiliter et rendre hommage à l'auteur de L'Etranger, le critique commence par rappeler le contexte de son oeuvre, l'enfance pauvre à Belcourt, le journalisme à Alger Républicain et la série d'exils vécus. Ensuite, il évoque des actions peu connues de Camus, après le 8 mai 1945 et pendant la guerre d'Algérie, pour la défense des Algériens. Enfin, il propose aux critiques de lire les déclarations et les romans de Camus dans le contexte du colonialisme de l'époque, c'est-à-dire de l'apartheid, afin de ne plus injustement condamner l'auteur .
Un Centre dans les marges: L'Amérique à la rescousse de la Francophonie?
Authors: Calargé Carla
Published: April 2011

Cette étude examine les débats générés par la publication, en mars 2007, du manifeste "Pour une littérature-monde." Elle se base sur les recherches de Pascale Casanova qui démontre que depuis le seizième siècle, Paris s'est établi comme la capitale mondiale de la République des Lettres; position unique qui lui assure le privilège de consacrer les écrivains internationaux, de dénationaliser leurs œuvres et de les transformer en patrimoine mondial. Cette place inégalée occupée par Paris n'en constitue pas moins une sorte d'impasse pour les auteurs francophones pour qui la France est aussi l'ancienne puissance coloniale. Comment, dès lors, Paris peut-il être juge objectif des œuvres "francophones"? La langue française peut-elle se départir de son pacte national pour devenir langue transnationale d'une production littéraire universelle? La solution pour les auteurs francophones serait-elle de trouver un tiers-espace neutre susceptible de leur permettre d'échapper aux tensions nationales et néocoloniales? L'Amérique peut-elle représenter et devenir cet espace?
Entretien avec Léonora Miano
Authors: Yoassi Trésor Simon
Published: April 2011

Ce texte est le fruit d'une série d'entretiens que l'auteure, Léonora Miano, a bien voulu nous accorder. D'abord près des jardins du Château de Vincennes à Paris et ensuite, à Case Western University de Cleveland en Novembre 2009. Nous abordons dans ces entretiens, sa venue fort remarquée dans le monde de l'écriture en 2005 avec L'Intérieur de la nuit , mais surtout, la verve de son écriture qui bouscule les tabous et révèle tout ce que certains auraient voulu garder sous le sceau par trop usé de la tradition. Nous passons en revue les grands thèmes de ses six publications et l'accueil que la critique leur a réservé. Abondamment lue en Europe, traduite en plusieurs langues, inscrite au programme scolaire de son pays d'origine, le Cameroun, Miano est une auteure résolument tournée vers l'avenir.
Le Chemin parcouru par la littérature et la langue françaises en Jordanie
Authors: Ghazu Mohamed
Published: April 2011

Cette recherche est destinée en premier lieu aux Jordaniens et aux Français qui n'ont pas une idée claire sur la présence de la littérature et la langue françaises en Jordanie, surtout dans les écoles et les universités. Nous avons souligné les problèmes que les étudiants affrontent en apprenant cette langue et sa littérature, et les raisons pour lesquelles ces étudiants choisissent une autre langue que la langue française. Pour que cette recherche soit utile à tous, nous avons cherché les solutions que nous croyons nécessaires pour la bien diffuser. Si nous avons insisté beaucoup plus sur la langue française, c'est parce que on ne peut connaître réellement la littérature, dans les écoles et les universités, qu'à travers la langue. Nous avons conclu que celles-ci ont besoin de beaucoup d'efforts et aussi d'une décision politique pour continuer dans le chemin qu'elles ont pris.
Bearing Logs on Our Shoulders: Reconciliation, Non-Reconciliation, and the Building of a Common World
Authors: Berkowitz Roger
Published: April 2011

On her first return visit to Germany in 1950, Hannah Arendt went walking in the Black Forest with Martin Heidegger. They discussed revenge, forgiveness, and reconciliation. Upon her return to New York, Arendt began her diary of thoughts, her Denktagebuch . The first seven pages of Arendt's Denktagebuch argue that reconciliation—and not revenge or forgiveness—is an essential example of political judgment. The connection between reconciliation and judgment means that only reconciliation, and not revenge or forgiveness, can respond to wrongs in a way that fosters the political project of building and preserving a common world. This essay argues that the question—"Ought I to reconcile myself to the world?"—is, for Arendt, the pressing political question of our age.
Acknowledgment and Disavowal as an Idiom for Theorizing Politics
Authors: Shulman George
Published: April 2011

This essay explores the limitations of the "turn" in political theory toward ethics and ethos. It does so by tracing how Stanley Cavell and Judith Butler use the concept of acknowledgment, and its conceptual twin disavowal, as an idiom by which to depict the ethics or ethos that should guide or frame political life. Rather than ask, who or what should we acknowledge and how—the normative and ontological questions driving theories that situate politics in relation to ethics or ethos—I ask, how does this idiom displace politics? By comparing Cavell and Butler to James Baldwin and Michael Rogin, who also use this idiom, my goal is not to reject but to politicize the concepts of disavowal and acknowledgment, for the sake of complicating, not reifying, the distinction between "politics" and "ethics."
Pleasure and Political Subjectivity: Fetishism from Freud to Agamben
Authors: Swiffen Amy , Kellogg Catherine
Published: April 2011

Freud's interest in sexual fetishism – an interest that spanned his entire career – lay in the way that fetishistic pleasure does not result from repressing a forbidden desire, but rather in displacing desire from a forbidden object onto an object available for use. In this way, fetishism recognizes the 'law of the father' but manages to evade an effect of its force. Our argument here is that the fetishistic relationship to law that Freud described can be used to understand aspects of Giorgio Agamben's influential approach to contemporary debates concerning law and sovereignty that have confused critics, specifically, the call to sever the nexus of violence and law as the only true political action. Said slightly differently, Agamben's invocation of 'whatever being' and a form of life after the state of exception, represents the limit threshold of law, but it is a limit that becomes evident only at the level of private enjoyment. The implication of our argument is that Agamben's utopian pronouncements are not best understood as theories of political action at all, but rather as fantasies of life untouchable by the violence that sovereign law requires.
In Situ Chemical Functionalization of a Single Carbon Nanotube Functionalized AFM Tip using a Correlated Optical and Atomic Force Microscope
Authors: Kaplan-Ashiri Ifat , Titus Eric J. , Willets Katherine A.
Published: April 2011

We present a method for performing nanoscale wet chemistry on single carbon nanotubes as well as spectroscopic characterization of the functionalized molecules using a coupled atomic force microscope (AFM) and optical microscope. An AFM probe was functionalized with a single multiwalled carbon nanotube and then locally oxidized by dipping it into nitric acid (HNO3) in situ using AFM manipulation. Raman scattering was collected from the carbon nanotube functionalized probe before and after the oxidation reaction. An increase in the Raman D band was observed after the acid treatment, demonstrating that oxidation had occurred. This is the first step towards developing a real-time technique for dynamic studies of chemical reactions on single nanoparticles/molecules.
Photoinduced Temporal Change of Surface-Potential Undulation on Alq3 Thin Films Observed by Kelvin Probe Force Microscopy
Authors: Ozasa Kazunari , Ito Hiromi , Maeda Mizuo , Hara Masahiko
Published: April 2011

The surface potential (SP) undulation on the surfaces of tris(8-hydroxyquinolinato) aluminum (III) (Alq3) films has been investigated with Kelvin probe force microscopy (KFM) and scanning near-field optical microscope (SNOM)-KFM. The SP undulation observed on the amorphous Alq3 films with thicknesses of up to 300 nm showed a cloud-like morphology of 200–300 nm in lateral size. The temporal change of SP undulation was traced through cyclic measurement with KFM observation with intermittent photoexposure, as well as in situ localized photoexcitation with SNOM-KFM. We concluded that the origin of the SP undulation is the nonuniform distribution of charged traps and drift mobility in the Alq3 films.
In-situ observation of Nb/Nb5Si3 two-phase alloys during bending at various temperatures
Authors: Miura Seiji , Tsutsumi Yukiyoshi , Mohri Tetsuo
Published: April 2011

In order to understand the deformation and fracture behavior of Nb-Si alloys, in-situ observation was conducted during bending of small specimens at room and high temperatures. Nb-Si alloy ingots containing 18.1 at.%Si, 1.5 at.%Zr and 100 ppmMg were prepared by arc melting, followed by uni-axial solidification in an optical floating zone apparatus and a heat-treatment to obtain Nb/Nb5Si3 two-phase microstructure. Chevron-notched specimens with a dimension of 1x2x10mm were used for in-situ observation of bending tests under a confocal laser scanning microscope (CLSM) at room temperature and at 1140 °C. At room temperature the Nb-Si alloy shows a fracture toughness of 8 MPa m1/2 and the crack propagation velocity seems to be not uniform, presumably due to the ductile Nb. At 1140 °C the toughness of the alloy was about 20 MPa m1/2 and slower plastic deformation prior to the cracking was observed. The SEM observation of crack surfaces revealed that plastic deformation of Nb enhances the toughness of the alloy.
Multiscale Modeling of Reinforced Epoxy Resins by Carbon Nanotubes and Graphene
Authors: Suggs Kelvin , Person Vernecia , Nicolas Chantel , Wang Xiao-Qian
Published: April 2011

Nanocomposites are of increasing interest due to their unique structural, electronic, and thermal properties. Simultaneously, multiscale molecular modeling is becoming more robust. Therefore computational models are able to be examined with increased accuracy, complexity, and dimension. Graphene based molecules are lauded for their conductive properties as well as their architecture-like geometry which may allow bottom up nanoscale fabrication of nanoscopic structures. Furthermore, these macrocycled molecules allow high interactivity with other molecules including highly tensiled polymers that yield other novel supramolecular structures when interacted. These supramolecular structures are being investigated in lieu of a variety of potential applications. Nanocomposites of cured epoxy resin reinforced by single-walled carbon nanotubes exhibit a plethora of interesting behavior at the molecular level. A fundamental issue is how the self-organized dynamic structure of functional molecular systems affects the interactions of the nano-reinforced composites. A combination of force-field based molecular dynamics and local density-functional calculations shows that the stacking between the aromatic macrocycle and the surface of the SWNTs manifests itself via increased interfacial binding. First-principles calculations on the electronic structures further reveal that there exists distinct level hybridization behavior for metallic and semiconducting nanotubes. In addition there is a monatomic increase in binding energy with an increase in the nanotube diameter. The simulation studies suggest that graphene nanoplatelets are potentially the best fillers of epoxy matrices. The implications of these results for understanding dispersion mechanism and future nanocomposite developments are discussed.
Tandem Photovoltaic Cells with Amorphous Silicon Cells and Organic Photovoltaic Cells
Authors: Kim Taehee , Jeon Jun Hong , Han Seung Hee , Lee Doh-Kwon , Kim Kyungkon
Published: April 2011

We demonstrate series-connected tandem photovoltaic cells consisting of hydrogenated amorphous silicon (a-Si:H) solar cells and polymer-based organic photovoltaic (OPV) cells. One of the limiting factors of a-Si:H solar cells is their narrow absorption spectrum as compared with that of crystalline silicon solar cells. In order to overcome this limitation, we fabricated a hybrid tandem solar cell by employing a solution-processed OPV subcell based on a low bandgap semiconducting polymer onto the a-Si:H subcell. It was found that the interfacial property of the hole transporting intermediate layer between the subcells strongly affects the photovoltaic property of the tandem cells. By using MoO3 as an efficient hole transporting intermediate layer instead of the conventional conducting polymer, we obtained the power conversion efficiency of 1.84% and the open-circuit voltage (VOC) of 1.50 V which corresponds closely to the sum of the VOCs of the subcells.
Effects of Chemical Modification of Indium-Tin-Oxide with Benzene Derivates on the Performance of Organic Photovoltaic Cells of ITO/CuPc/C60/BCP/Al
Authors: Sarangerel Khayankhyarvaa , Delgerjargal Altantsetseg , Delgertsetseg Byambasuren , Ganzorig Chimed
Published: April 2011

Organic thin film photovoltaic (PV) cells have attracted attention because of their ease of fabrication and potential for low cost production. In this paper, we study the effects of chemical modification of indium-tin-oxide (ITO) on the performance of organic PV cells. The organic PV cells are fabricated, with the cell configuration of ITO/copper phthalocyanine (CuPc) (20 nm)/fullerene (C60) (40 nm)/Al with and without bathocuproine (BCP) (10 nm) between C60 and Al. By the use of para-substituted benzenesulfonyl chlorides with different terminal groups of H- and Cl-, the energy offset at the ITO/CuPc interface is tuned widely depending upon the interface dipoles and thus the correlation between the change in the ITO work function and the performance of the PV cells by chemical modification is examined.
Lattice-Symmetry-Driven Phase Competition in Vanadium Dioxide
Authors: Tselev A. , Luk’yanchuk I. A. , Ivanov I. N. , Budai J. D. , Tischler J. Z. , Strelcov E. , Kolmakov A. , Kalinin S. V.
Published: April 2011

We performed group-theoretical analysis of the symmetry relationships between lattice structures of R, M1, M2, and T phases of vanadium dioxide in the frameworks of the general Ginzburg-Landau phase transition theory. The analysis leads to a conclusion that the competition between the lower-symmetry phases M1, M2, and T in the metal-insulator transition is pure symmetry driven, since all the three phases correspond to different directions of the same multi-component structural order parameter. Therefore, the lower-symmetry phases can be stabilized in respect to each other by small perturbations such as doping or stress.
Four color stacked white organic light-emitting diodes utilizing
the concept of triplet harvesting
Authors: Rosenow Th. C. , Olthof S. , Reineke S. , Lüssem B. , Leo K.
Published: April 2011

Organic light-emitting diodes (OLEDs) are developing into a competitive
alternative to conventional light sources. Nevertheless, OLEDs need further
improvement in terms of efficiency and color rendering for lighting
applications. Fluorescent blue emitters allow deep blue emission and high
stability, while phosphorescent blue emitter still suffer from insufficient
stability. The concept of triplet harvesting is the key for achieving
internal quantum efficiencies up to 100 % and simultaneously benefiting from
the advantages of fluorescent blue emitters. Here, we present a stacked OLED
consisting of two units comprising four different emitters in total. The
first unit takes advantage of the concept of triplet harvesting and combines
the light emission of a fluorescent blue and a phosphorescent red emitter.
The second unit emits light from a single emission layer consisting of a
matrix doped with phosphorescent green and yellow emitters. With this
approach, we reach white color coordinates close to the standard illuminant
A and a color rendering index of above 75. The presented devices are
characterized by high luminous efficacies of above 30 lm/W on standard glass
substrates without outcoupling enhancement.
Degradation Studies of Colloidal Quantum Dot Light-Emitting
Diodes
Authors: Liu Jie , Xie Chuang , Zhang Yu , Hu Wenjia , Pickering Shawn , You Guanjun , Wang Andrew Y. , Xu Jian
Published: April 2011

The degradation mechanism of CdSe/ZnS quantum dots (QDs) light-emitting
diodes (LEDs) was investigated with steady-state and time-resolved
photoluminescence measurements. Our study reveals that the degradation is
associated with the decreasing quantum efficiency of the CdSe/ZnS QDs in the
devices. Two mechanisms that cause the efficiency reduction were verified in
the experiments: i.e., thermal instability and luminescence quenching.
Design of Optical Isolator with TiO2/(CeY)3Fe5O12 Guiding Layer
Authors: Yokoi Hideki , Ikeya Shintaro , Imada Tsuyoshi
Published: April 2011

An optical isolator with a TiO2/(CeY)3Fe5O12 guiding layer was studied. A nonreciprocal phase shift was calculated in the magneto-optic waveguide with the TiO2/(CeY)3Fe5O12 guiding layer at a wavelength of 1.55 μm. By employing a multimode interference coupler as coupling devices, the total device length of approximately 600 μm was achieved. An interferometric optical isolator with distinct layer structures, which could be operated in a unidirectional magnetic field, was also designed.
Polarization Dependence and Relaxation of the Current in Polycrystalline Ferroelectric Pb(ZrTi)O3 Film
Authors: Delimova L. A. , Yuferev V. S. , Ankudinov A. V. , Gushchina E. V. , Grekhov I. V.
Published: April 2011

Using Scanning Spreading Resistance Microscopy and direct current-voltage measurements, a long-relaxation transport current in polycrystalline PZT films is shown to depend on the polarization direction and voltage rise rate, the latter is typical for a capacitive current. The clockwise current hysteresis is observed at any polarization of the film. We suppose that the long current relaxation is due to recharge of traps, which participate in screening of polarization charges on PZT grain boundaries. The polarization charges response to applied bias for a short time, whereas the traps response to variation of the polarization charges takes much longer time.
Ion Beam Irradiation-induced Amorphization in Nano-sized KxLnyTa2O7-v Tantalate Pyrochlore
Authors: Lu Fengyuan , Nyman May , Shen Yiqiang , Dong Zhili , Wang Gongkai , Zhang Fuxiang , Ewing Rodney , Lian Jie
Published: April 2011

The radiation response of nano-sized tantalate pyrochlores, KxLnyTa2O7-v (Ln = Gd, Y, and Lu) with average grain sizes of ~ 10 nm was investigated using 1 MeV Kr2+ ion beam irradiations. EDS measurements and XRD refinement reveal that the Y3+ and Lu3+-doped samples consist of two pyrochlore phases as K0.8YTa2O6.9/K0.4Y0.8Ta2O6.4 and KLuTa2O7/K0.4Lu0.8Ta2O6.4 respectively; whereas a single phase of K0.8GdTa2O7 only exists in the Gd3+-doped tantalate pyrochlore. In situ TEM observation confirms ion beam-induced amorphization occurring in all of the nano-sized KxLnyTa2O7-v. At elevated temperatures, both K0.8GdTa2O7 and K0.8YTa2O6.9/K0.4Y0.8Ta2O6.4 exhibit higher radiation tolerance than KLuTa2O7/K0.4Lu0.8Ta2O6.4, and the critical temperatures of K0.8GdTa2O7 and K0.8YTa2O6.9/K0.4Y0.8Ta2O6.4 are estimated to be 1167 ± 41 K and 1165 ± 34 K, respectively, lower than that of KLuTa2O7/K0.4Lu0.8Ta2O6.4 (~ 1291 K). The K0.8GdTa2O7, K0.8YTa2O6.9 and KLuTa2O7 phases have less structural deviation from the parent fluorite structure and thus may be responsible for the overall radiation tolerance. The high K+ occupancy at pyrochlore A sites in KLuTa2O7 is believed to contribute to the decrease of radiation tolerance, consistent with the large ionic radius ratio of K+/Ta5+. These results highlight that the radiation tolerance of nanostructured materials is highly compositional dependent, and nano-sized tantalate pyrochlores are sensitive to radiation damage.
High Temperature Thermal Analysis of Graphite and Silicon Carbide with Millimeter-Wave Radiometry
Authors: Woskov Paul P. , Sundaram S. K.
Published: April 2011

Millimeter-wave thermal analysis instrumentation is being developed for characterization of high temperature materials required for diverse fuel and structural needs in extreme high temperature reactor environments. A two-receiver 137 GHz system with orthogonal polarizations for anisotropic properties resolution has been implemented at MIT and is being tested with graphite and silicon carbide specimens at temperatures up to 1300ºC. Real time measurement sensitivity to submillimeter surface displacement and simulated anisotropic surface emissivity is demonstrated.
FLUCTUATION OF INTERNAL FRICTION IN METALLIC GLASSES
Authors: Miyauchi Y. , Tamura R. , Hiki Y.
Published: April 2011

Internal friction (IF) of a metallic glass Zr55Cu30Al10Ni5 has been measured near the glass transition temperature Tg (= 666 K). The measurement is performed by using DMA (TA Instrument) apparatus at a frequency of 0.01 Hz for a specimen stabilized by annealing. The specimen is kept at a constant temperature T, and the IF value Q-1 is measured as a function of time t. A fluctuation of Q-1 with time is seen, and the magnitude of the fluctuation, F(t), is derived from the Q-1-vs-t data. F(t) is Fourier transformed to the frequency spectrum F(f). Such experiment and analyses are carried out at various temperatures near Tg. A characteristic peak (f ~ 10-3 Hz) is found in the spectrum F(f) in the glass transition region.
Composition, Bonding state, and Electrical Properties of Carbon Nitride Films Formed by Electrochemical Deposition Technique
Authors: Kiyota Hideo , Higashi Mikiteru , Kurosu Tateki , Chiba Masafumi
Published: April 2011

Composition, bonding state, and electrical properties of CNx films formed by electro-chemical deposition using liquid acrylonitrile were studied. X-ray photoelectron spectra reveal that C, N, and O are major components of the deposited films. From analysis of C 1s and N 1s spectra, the major bonding state in the CNx film is attributed to a mixture of C≡N and partially hydrogenated C=N bond. Metal-insulator-semiconductor capacitors incorporating the CNx insulating layers are fabricated to evaluate the electrical properties of the deposited films. The lowest dielectric constant k of the CNx film is determined to be 2.6 from the accumulation capacitance and the thickness of the film. It is demonstrated that the CNx film formed by electrochemical deposition is a promising low-k material for use in ultralarge-scale integration multilevel interconnections.
Irradiation Damage in Dual Beam Irradiated Nanostructured FeCrAl Oxide Dispersion Strengthened Steel
Authors: Richter A. , Chen C.-L. , Mücklich A. , Kögler R.
Published: April 2011

An oxide dispersion strengthened steel is produced which contains Y-Al-Ti-O nanoparticles with an average diameter of 21 nm. HRTEM analysis shows that the chemical composition of the Y2O3 oxide is modified with perovskite YAlO3 (YAP), Y2Al5O12 garnet (YAG) and Y4Al2O9 monoclinic (YAM) particles. Irradiation of these alloys was performed with a dual ion beam system operating simultaneously with 2.5 MeV Fe+ to 31 dpa and 350 keV He+ to 18 appm/dpa. Ion bombardment causes atomic displacements resulting in vacancy and self-interstitial lattice defects and dislocation loops. TRIM calculations for ODS steel indicate a clear spacial separation between vacancies and self-interstitials at which the vacancy distribution is close to the surface and the interstitials are deposited at a deeper position. The helium atoms mainly accumulate in the vacancies. Fine He cavities with diameters of a few nanometers were identified in HRTEM images. Additionally to structural changes, irradiation generated defects also affect the mechanical properties of the ODS steel. These were investigated by nanoindentation, which is a suitable measuring method as the irradiation damage is created within a thin surface layer. A clear hardness increase in the irradiated depth region was observed, which reaches a maximum close to the surface. This indicates the He condensation in the vacancy dominated region predicted by the simulations.
Post-Processing Electrospun Fibers
Authors: Schauer Caroline L. , Austero Marjorie S. , Toth Amanda C.
Published: April 2011

Electrospinning is an inexpensive and simple method of producing non-woven
fiber mats. Electrostatic forces are employed to produce the mats, which
intrinsically have larger specific surface to volume ratio and smaller pores
than traditional fibers. Fibrous mats are typically used in a wide variety
of industries such as filter media, tissue engineering, and sensors.
Chitosan, the N-deacetylated derivative of chitin, is
environmentally friendly, non-toxic, biodegradable, and anti-bacterial.
However, due to chitosan’s solubility in aqueous acids, it is electrospun
using trifluoroacetic acid (TFA). Modified chitosans, such as
carboxymethylchitosan, are currently under investigation as a means of
creating designed nanofibrous mats with specific chemistries. However,
typically an entirely new set of electrospinning conditions has to be
developed for each novel chemistry due to differences in solubility and
viscosity. In the present study, we have electrospun chitosan mats and
post-processed the fibers. Two different post-processing conditions were
employed. One post-production procedure, featuring vapor-phase
glutaraldehyde, effectively crosslinks the fiber mats utilizing a Schiff
base imine functionality. In another post-processing procedure, the as-spun
mats are solution-phase post-processed by chemically functionalizing the
mats with cyano, carboxylic acids and thiol groups. While both methods
maintained fiber shape and characteristics, there is a definite increase in
fiber diameters due to processing. FTIR, NMR, SEM and tensile testing have
been performed on the pre- or post-processed fiber mats. Investigations into
the percent modification are currently underway.
Magnetic properties of acrylic UV-cured films containing magnetite nanoparticles
Authors: Chiolerio Alessandro , Allia Paolo , Tiberto Paola , Suber Lorenza , Marchegiani Giada , Sangermano Marco
Published: April 2011

Acrylic based films containing thermo-chemically synthesized magnetite nanoparticles (NPs) were prepared by UV-curing. A stable dispersion of Fe3O4 NPs in n-hexane was added to polyethylene glycol diacrylate (PEGDA) oligomer or to hexanediol diacrylate (HDDA) oligomer, producing a blend whose viscosity matches the processing requirements for inkjet printing technology. Morphologic characterization is provided by means of Field Effect SEM on a representative nanocomposite section.

By real-time FT-IR analysis it was shown that Fe3O4 NPs are able to initiate radical chain-grown polymerization under UV light, for what concerns the HDDA matrix. Tight cross-linked transparent polymeric films were obtained after 1 minute of UV irradiation.

The magnetic properties of the produced films were studied by means of an Alternating-Gradient Force Magnetometer (AGFM) in the temperature range 10 – 300 K and up to 18 kOe. The isothermal magnetization curves of both HDDA and PEGDA -based nanocomposites showed that these hybrid systems must be described as interacting superparamagnets (ISP) characterized by inter-particle magnetic interactions dominating over intra-particle effects.
Magneto-Optic Indicator Films for Forensics
Authors: Krafft Charles , Tkachuk Sergiy , Lang Garrett , Bowen David , Mayergoyz Isaak. D.
Published: April 2011

Garnet films based on (BiPrGdLu) (FeGa) have been grown on (210) and (100) oriented SGGG substrates. (210) films with an easy plane of magnetization provided optimal imaging contrast. Incorporation of Au nanoparticles into an epitaxially grown film was done and these films show an increase in Faraday rotation, ostensibly due to the plasmon resonance effect.
All-Semiconducting Nanotube Networks: Towards High Performance Printed Nanoelectronics
Authors: Rouhi N. , Jain D. , Zand K. , Burke P. J.
Published: April 2011

In this work, we present progress towards devices fabrication using all semiconducting nanotubes as the starting material. Individual nanotubes are known to have intrinsic mobility of more than 10,000 cm2/V-s but using a network of nanotubes will decrease this mobility because of tube-tube screening effect and junction resistance. Here we are using solution-based deposition of purified 99% semiconducting single-walled nanotubes as the channel in field effect transistors. DC analysis of devices’ characterization shows a high mobility, more than 50 cm2/Vs, and good on/off ratio in the range of more than 103 and 104. A critical issue is the ink formulation and dependence of electronic properties on the nanotube density after deposition. In addition, the channel length also plays an important role in controlling both mobility and on/off ratio.
Carbon nanofiber-based photonic crystals – fabrication, diffraction and ellipsometry investigations
Authors: Rehammar Robert , Magnusson Roger , Lassesson Andreas , Arwin Hans , Kinaret Jari , Campbell Eleanor
Published: April 2011

Carbon nanofibers were used as building blocks for two-dimensional photonic crystal slabs. Electron beam lithography and chemical vapor deposition were used to fabricate regular arrays and random patterns of nanofibers. The optical properties of the samples were investigated using a diffraction measurement setup, as well as reflection ellipsometry. We find that carbon nanofiber regularity has a strong effect on both diffractive and specular optical properties. This shows that ellipsometry can be a valuable tool to study properties of carbon nanofiber arrays. It also shows that carbon nanofibers provide an interesting candidate as building blocks for nanostructured optical components.
Size Effect on Bending Properties of Diamond-Like Carbon Nanopillar Fabricated by Focused Ion-Beam Assisted Chemical Vapor Deposition
Authors: Kogo Yasuo , Harada Hiroyuki , Shibutani Yoji , Sakamoto Naomichi , Yasuno Takuya
Published: April 2011

Bending tests of Diamond-Like Carbon (DLC) nanopillars fabricated by Focused Ion-Beam assisted Chemical Vapor Deposition (FIB-CVD) were carried out in a scanning electron microscope (SEM) to investigate their mechanical behavior. Special attention was paid on the effect of the specimen size. The nanopillars with nano-sized diameter and micro-sized length were grown using spot irradiation without scanning FIB. The diameter of the nanopillars was changed in the range of 100 ~ 1000 nm by changing the magnitude of defocusing FIB.

In the bending tests, brittle fracture was observed for the nanopillars with diameter of 1000 nm. On the contrary, large deformation without brittle fracture was confirmed in the specimens with diameter of 300 nm. In addition, the pillar recovered its original shape after unloading without any permanent deformation even after the large deformation.

Transmission electron microscope (TEM) analysis revealed that the pillars had uniform amorphous structures regardless of the diameters if the FIB was defocused during processing. In addition, similar gallium (Ga) content and sp2/sp3 fraction were observed in both specimens. These results indicate that difference in microstructures cannot be the reason for that in mechanical behavior. In other words, it must be caused by the intrinsic size effect on the mechanical properties of DLC fabricated by FIB-CVD process.
Molecular Recognition Mechanisms of Calmodulin Examined by
Perturbation-Response Scanning
Authors: Aykut A. Ozlem , Atilgan Ali Rana , Atilgan Canan
Published: April 2011

We analyze the apo and holo calmodulin (CaM) structures by sequentially
inserting a perturbation on every residue of the protein, and monitoring the
linear response. Residue crosscorrelation matrices obtained from 20 ns long
molecular dynamics simulation of the apo-form are used as the kernel in the
linear response. We determine two residues whose perturbation equivalently
yields the experimentally determined displacement profiles of CaM, relevant
to the binding of the trifluoperazine (TFP) ligand. They reside on
structurally equivalent positions on the N- and C-terminus lobes of CaM, and
are not in direct contact with the binding region. The direction of the
perturbation that must be inserted on these residues is an important factor
in recovering the conformational change, implying that highly selective
binding must occur near these sites to invoke the necessary conformational
change.
Thermo-Mechanical behavior at Nano-Scale and Size Effects in Shape Memory Alloys
Authors: San Juan Jose , Nó Maria L. , Schuh Christopher A.
Published: April 2011

Shape Memory Alloys (SMA) undergo reversible martensitic transformation in response to changes in temperature or applied stress, exhibiting specific properties of superelasticity and shape memory. At present there is a high scientific and technological interest to develop these properties at small scale, to apply SMA as sensors and actuators in MEMS technologies. In order to study the thermo-mechanical properties of SMA at micro and nano scale, instrumented nano indentation is being widely used for nano compression tests. By using this technique, superelasticity and shape memory at the nano-scale has been demonstrated in micro and nano pillars of Cu-Al-Ni SMA. However the martensitic transformation seems to exhibit a different behavior at small scale than in bulk materials and a size effect on superelasticity has been recently reported. In the present work we will overview the thermo-mechanical properties of Cu-Al-Ni SMA at the nano-scale, with special emphasis on size effects. Finally, the above commented size effects will be discussed on the light of the microscopic mechanisms controlling the martensitic transformation at nano scale.
Strengthening effect of twin boundaries in bcc crystal evaluated through a micro-bending test
Authors: Karasawa Yuki , Mark Chang Tso-Fu , Shibata Akinobu , Sone Masato
Published: April 2011

In the present study, the strengthening effect of nano-scale twins in body-centered cubic (bcc) crystal was evaluated using micro-sized cantilever type specimen which contained the nanotwinned region (midrib) in ferrous lenticular martensite. The SEM observations of the micro-sized specimen after bending deformation indicated that midrib can act as barriers against dislocations, resulting in slip localization and non-localization across midrib. The load-displacement curve obtained by bending test showed that twin boundaries significantly enhance the critical resolved shear stress of bcc.
Observation of Large, Anomalous Pyroelectric Response in AlN Thin Films
Authors: Crisman Everett , Vasilyev Vladimir , Drehman Alvin , Webster Richard
Published: April 2011

We have observed a pyroelectric effect (PE) in reactively sputtered aluminum nitride (AlN) thin films that is typically a factor of twenty greater than commercial pyroelectric materials such as triglycine sulfate (TGS). This is most likely due to an extrinsic effect since the known crystalline structures of AlN are too symmetric to allow such high values for the PE response. Preliminary annealing studies support the assumption that residual strains remaining from the AlN thin film deposition are the most likely source of the anomalously high PE response. The results of these studies are presented along with some measurements that indicate a still higher PE response might be obtainable.
Piezoelectric Multimaterial Fibers
Authors: Chocat Noémie , Wang Zheng , Egusa Shunji , Ruff Zachary M. , Stolyarov Alexander M. , Shemuly Dana , Sorin Fabien , Rakich Peter T. , Joannopoulos John D. , Fink Yoel
Published: April 2011

Here we report on the design, fabrication, and characterization of fiber containing an internal crystalline non-centrosymmetric phase enabling piezoelectric functionality over extended fiber lengths [1]. A ferroelectric polymer layer of 30 μm thickness is spatially confined and electrically contacted by internal viscous electrodes and encapsulated in an insulating polymer cladding hundreds of microns in diameter. The structure is thermally drawn in its entirety from a macroscopic preform, yielding tens of meters of piezoelectric fiber. Electric fields in excess of 50V/μm are applied through the internal electrodes to the ferroelectric layer leading to effective poling of the structure. To unequivocally establish that the internal copolymer layer is macroscopically poled we adopt a two-step approach. First, we show that the internal piezoelectric modulation indeed translates to a motion of the fiber’s surface using a heterodyne optical vibrometer at kHz frequencies. Second, we proceed to an acoustic wave measurement at MHz frequencies: a water-immersion ultrasonic transducer is coupled to a fiber sample across a water tank, and frequency-domain characterizations are carried out using the fiber successively as an acoustic sensor and actuator. These measurements establish the broadband piezoelectric response and acoustic transduction capability of the fiber. The potential to modulate sophisticated optical devices is illustrated by constructing a single-fiber electricallydriven device containing a high-quality-factor Fabry-Perot optical resonator and a piezoelectric transducer.
Thermoelectric Properties of New Thallium Tellurides
Authors: Sankar Cheriyedath Raj , Bangarigadu-Sanasy Savitree , Kleinke Holger
Published: April 2011

Ternary thallium chalcogenides of the formula Tl4MQ4, whereM= Zr and Hf andQ= S, Se, and Te were synthesized and characterized. Our X-ray diffraction studies on suitable single crystals reveal that the sulphides and selenides are isostructural, with monoclinic space groupP, whereas the corresponding tellurides crystallize in the rhombohedral crystal system (R). The structures of the sulphides and selenides are comprised of zigzag chains of edge-sharingMQ6octahedra, whereas theMTe6octahedra are interconnected via common faces to form linear trimeric units. In all cases, the atoms adopt common oxidation states, namely Tl+,M4+, andQ2–. The electronic structure calculations using the linear muffin tin orbital (LMTO) method predicted band gaps of 1.7 eV, 1.3 eV and 0.3 eV for the sulphides, selenides and tellurides, respectively, implying sulphides and selenides are large band gap materials, and the tellurides narrow gap semiconductors. Their electronic transport properties are also evaluated with respect to the thermoelectric energy conversion.
The observation of the lattice defect formation during hydrogenation and dehydrogenation in La(Ni,Sn)5 by in-situ positron lifetime measurement
Authors: Sakaki Kouji , Nakamura Yumiko , Shirai Yasuharu , Bowman Robert C , Akiba Etsuo
Published: April 2011

To clarify the effect of Sn substitution for Ni of LaNi5 on the lattice defect formation during the hydrogenation and dehydrogenation processes, in-situ positron lifetime measurements were per-formed in LaNi4.93Sn0.27. During the hydrogenation, the mean positron lifetime, τm, monotonically increased up to 175 ps which is almost same as calculated positron lifetime for vacancy. This shows vacancy introduction by hydrogenation. The τm mean positron lifetime decreased down to 135 ps with hydrogen content during the dehydrogenation. It shows that the vacancies are removed from the lattice during the dehydrogenation. These results show that vacancies in LaNi4.93Sn0.27 are intro-duced and removed reversibly during the hydrogenation and dehydrogenation. The concentra-tions of vacancy and dislocation were 1 × 10−5 and 6 × 109 cm−2, respectively. These values are two orders lower than those in LaNi5.
H-Diffusion in the H-Storage TiVMnCr Alloys as Deduced from Absorption and Mechanical Spectroscopy Experiments
Authors: Mazzolai Giovanni , Biscarini Andrea , Coluzzi Bruno , Mazzolai Fabio Massimo , Tuissi Ausonio
Published: April 2011

The low H content portion of the PCT absorption curves of the 40Ti-xV-(50-x)Mn-10Cr alloys exhibits a plateau, whose pressure has been determined together with the solubility limit of H in the α–phase (solid solution). The chemical (Dc) and Einstein (DE) diffusion coefficients of H have been deduced from H absorption kinetics (273 K-1100 K) and from mechanical spectroscopy (150 K-200 K), which has revealed a Snoek-type of anelastic relaxation. The combined Arrhenius plot of DE and Dc gives the following parameters for H diffusion: W=0.318±0.005 eV, D0=(4±1)×10−7 m2/s (36 V alloy) and W=0.352±0.005 eV, D0=(5±1)10−7 m2/s (32 V alloy).
On the Thermoelectric Properties of Layered Cobaltates
Authors: Li Qiang
Published: April 2011

A study on the thermoelectric properties of layered cobaltates is presented, based on the dynamic mean field theory for strongly correlated electron systems. Electron correlation results in a crossover from coherent quasi-particle excitation at low temperature to incoherent excitation at high temperatures in cobaltates. With an extremely narrow quasi-particle bandwidth (hωc ∼ 50 meV), the thermal destruction of Fermi-liquid occurs at the moderate crossover temperature TM (∼ 200 K), and suggests a new scaling for thermoelectric power S of cobaltates (S ∼ kT/hωc ∼ T/TM) at low temperatures. At high temperatures, the dominating incoherent excitation leads to a weak temperature dependent S, and electric resistivity ρ approaches the Mott-limit ha/e2 ∼ a few mΩ·cm for cobaltates, where a is a lattice constant.