Strengthening Mechanisms And Dislocation Dynamics In Twinned Metal Nanowires

Microtwins are frequently observed in face-centered-cubic (fcc) metal nanowires with low stacking fault energy. The authors have previously reported that the tensile Yield strength of copper nanowires can be increased by, the presence of twin boundaries. lit this work, simulations are carried out under both uniaxial tension and compression loading, to demonstrate that the strengthening effects are inherent to these nanowires, independent of the loading condition (tensile/compressive). It appears that the strengthening mechanism of the twinned nanowires can be attributed to stress redistribution due to the change of crystallographic orientations across twin boundaries, which requires larger external stress to make them Yield as compared to the twin-free wire.

Alternating Starvation Of Dislocations During Plastic Yielding In Metallic Nanowires

Using molecular dynamics simulations, we show that the mechanical deformation behaviors of single-crystalline nickel nanowires are quite different from their bulk counterparts. Correlation between the obtained stress-strain curves and the visualized defect evolution during deformation processes clearly demonstrates that a sequence of complex dislocation slip events results in a state of dislocation starvation, involving the nucleation and propagation of dislocations until they finally escape from the wires, so that the wires deform elastically until new dislocations are generated. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Deformation mechanisms of face-centered-cubic metal nanowires with twin boundaries

This letter addresses the issue of deformation mechanisms and mechanical tensile behavior of the twinned metal nanowires using atomistic simulations. Free surfaces are always the preferential dislocation nucleation sites in the initial inelastic deformation stage, while with further plastic deformation, twin boundary interfaces will act as sources of dislocations with the assistance of the newly formed defects. The smaller the twin boundary spacing, the higher the yielding stresses of the twinned nanowires. Twin boundaries, which serve both as obstacles to dislocation motion and dislocation sources, can lead to hardening effects and contribute to the tensile ductility. This work illustrates that the mechanical properties of metal nanowires could be controlled by tailoring internal growth twin structures. (c) 2007 American Institute of Physics.

Aquaculture Asia, Vol.14, No.4, pp.1-52, October - December 2009

Sustainable aquaculture Peter Edwards writes on rural aquaculture Edwards, P. Mussel farming initiatives in North Kerala, India: A case of successful adoption of technology leading to rural livelihood transformation Laxmilatha, P., Thomas, S., Asokan, P.K., Surendranathan, V.G., Sivadasan, M.P., and Ramachandran, N.P. Selective study on the availability in indigenous fish species having ornamental value in some districts of West Bengal Panigrahi, A.K., Dutta, S. and Ghosh, I. Aquaculture livelihoods service centres in Aceh, Indonesia: A novel approach to improving the livelihoods of small scale fish farmers Ravikumar, B. and Yamamoto, K. Research and farming techniques e-Sagu Aqua - an innovative information and communication technology model for transfer of technology for aquaculture Vimala, D. D., Ravisankar, T., Mahalakshmi, P., and Kumaran, M. Freshwater pearl crop: an emerging enterprise in the Indian subcontinent Misra, G., Jena, J. and Kumar, K. Genetics and biodiversity Preliminary risk assessment of Pacific white leg shrimp (P. vannamei) introduced to Thailand for aquaculture Senanan, W., Panutrakul, S., Barnette, P., Chavanich, S., Mantachitr, V., Tangkrock-Olan, N., and Viyakarn, V. Farmer profile Aquatic animal health Asian fish health experts visit Australia Olsen, L. and Ingram, B. (Fisheries Victoria) Black gill disease of cage-cultured ornate rock lobster Panulirus ornatus in central Vietnam caused by Fusarium species Nha, V.V., Hoa, D.T. and Khoa, L.V. Marine Finfish Aquaculture Network Effects of the partial substitution fish oil by soybean oil in the diets on muscle fatty acid composition of juvenile cobia (Rachycentron canadum) Hung, P.D. and Mao, N.D. Growth response of cobia Rachycentron canadum (Pisces: Rachycentridae) under the hypersaline conditions of the Emirate of Abu Dhabi Yousif, O.M.*, Kumar, K.K. and Abdul-Rahman, A.F.A. NACA Newsletter

Reduced deep-tissue image degradation in three-dimensional multiphoton microscopy with concentric two-color two-photon fluorescence excitation

We theoretically demonstrate that enhanced penetration depth in three-dimensional multiphoton microscopy can be achieved using concentric two-color two-photon (C2C2P) fluorescence excitation in which the two excitation beams are separated in space before reaching their common focal spot. Monte Carlo simulation shows that, in comparison with the one-color two-photon excitation scheme, the C2C2P fluorescence microscopy provides a significantly greater penetration depth for imaging into a highly scattering medium. (C) 2008 Optical Society of America.

Two-color two-photon excitation of indole using a femtosecond laser regenerative amplifier

The fluorescence emission from indole resulting from two-color two-photon (2C2P) excitation with 400 and 800 nm wavelengths is observed, using the second harmonic and fundamental wavelength of a 800 nm 40 fs pulsed Ti:Sapphire femtosecond (fs) regenerative amplifier operating at a repetition rate of 1 kHz. By delaying one fs laser pulse relative to the other, the cross correlation of fluorescence is observed, which indicates the generation of 2C2P fluorescence signal in the experiment. The strongest 2C2P fluorescence emission characterized by the peak of cross correlation curve suggests optimal temporal overlap of the two fs laser pulses. The 2C2P fluorescence signal is linearly dependent on the total excitation intensity. The fluorescence signals with 400 nm and 800 nm irradiation alone are also demonstrated and discussed in this paper. (C) 2008 Elsevier B.V. All rights reserved.

Information-theoretic Studies and Capacity Bounds: Group Network Codes and Energy Harvesting Communication Systems

Network information theory and channels with memory are two important but difficult frontiers of information theory. In this two-parted dissertation, we study these two areas, each comprising one part. For the first area we study the so-called entropy vectors via finite group theory, and the network codes constructed from finite groups. In particular, we identify the smallest finite group that violates the Ingleton inequality, an inequality respected by all linear network codes, but not satisfied by all entropy vectors. Based on the analysis of this group we generalize it to several families of Ingleton-violating groups, which may be used to design good network codes. Regarding that aspect, we study the network codes constructed with finite groups, and especially show that linear network codes are embedded in the group network codes constructed with these Ingleton-violating families. Furthermore, such codes are strictly more powerful than linear network codes, as they are able to violate the Ingleton inequality while linear network codes cannot. For the second area, we study the impact of memory to the channel capacity through a novel communication system: the energy harvesting channel. Different from traditional communication systems, the transmitter of an energy harvesting channel is powered by an exogenous energy harvesting device and a finite-sized battery. As a consequence, each time the system can only transmit a symbol whose energy consumption is no more than the energy currently available. This new type of power supply introduces an unprecedented input constraint for the channel, which is random, instantaneous, and has memory. Furthermore, naturally, the energy harvesting process is observed causally at the transmitter, but no such information is provided to the receiver. Both of these features pose great challenges for the analysis of the channel capacity. In this work we use techniques from channels with side information, and finite state channels, to obtain lower and upper bounds of the energy harvesting channel. In particular, we study the stationarity and ergodicity conditions of a surrogate channel to compute and optimize the achievable rates for the original channel. In addition, for practical code design of the system we study the pairwise error probabilities of the input sequences.

Relaciones comerciales entre China y la Unión Europea

La economía china ha experimentado en las últimas tres décadas una profunda transformación, hasta convertirse en el momento actual en el centro de la actividad manufacturera a escala mundial. Tal evolución no ha sido ajena a la metamorfosis sufrida por la sociedad china, tras un convulso siglo XX bajo los mandatos en la segunda mitad del mismo de Mao Tse Tung y Deng Xiaoping. La Unión Europea (UE) ha tratado de estrechar los lazos mercantiles con el gigante chino, fundamentalmente a través de la firma de acuerdos comerciales, aunque obstaculizados por algunos conflictos que han surgido en los últimos años. El análisis de las relaciones bilaterales entre China y la UE refleja una progresiva intensidad del comercio entre ambas regiones y la tendencia hacia la profundización del saldo negativo para la UE, hecho que ha generado tensiones diplomáticas. En un entorno más conflictivo recientemente en las relaciones bilaterales, la UE debería así mismo introducir reformas para mejorar su competitividad exterior y optimizar el vínculo comercial con China.

La historia a través del cine. China y Japón en el siglo XX

Este volumen presenta ocho películas sobre Japón y China englobadas en siete artículos. Cronológicamente abarcan un espectro amplio, particularmente en el caso japonés, que ya era una potencia cinematográfica desde los inicios del séptimo arte. El caso chino es algo diferente, con películas más bien recientes, aunque en este caso la temática histórica tiene más fuerza que en el caso japonés, en que las películas de corte histórico están casi ausentes. Así, para China, Araceli Rodríguez (Universidad Rey Juan Carlos) nos presenta La Linterna Roja, del genial Zhang Yimou, obra de temática histórica sobre la China rural de los años veinte. Fernando Martínez Rueda (Universidad del País Vasco) comenta la excelente ¡Vivir!, del mismo director, Zhan Yimou, que habla de la vida cotidiana de la China de Mao a través de los ojos de un propietario (afortunadamente para él) arruinado. Por su parte, Ricardo Martín de la Guardia (Universidad de Valladolid) nos presenta, en Juntos, la China actual con su contraste de modernidad y tradición y la difícil relación campo-ciudad que en todos los ámbitos se da hoy día en aquel país. En el caso japonés Carlos Giménez Soria (Film-Historia, Universitat de Barcelona) analiza dos películas de Kurosawa (El Ángel Ebrio y El Perro Rabioso), en las que se muestran aspectos del Japón de posguerra desde el punto de vista del neorrealismo japonés y del cine negro. En cuanto al principal trabajo de Yasujiro Ozu (Cuentos de Tokio), José Mª Tápiz lo analiza desde la perspectiva de la vida personal del gran director de cine. Otras dos películas merecen ser consideradas aparte: una de ellas de temática china (El Imperio del Sol) y la otra de tema japonés (Lost in Translation). Si bien entran dentro de la clasificación inicial, ambas han sido realizadas por directores extranjeros: la primera por Steven Spielberg y la segunda por Sofia Coppola. Podrían definirse como películas de introducción o aproximación, lo cual es de agradecer en dos culturas que, por ser muy diferentes a la nuestra, a veces requieren ser explicadas. Ambas fueron éxitos de taquilla, lo que invita a pensar sobre la utilidad de este tipo de género. A nadie se le escapa la objetiva utilidad de este tipo de cine, a la vez que el peligro que implica si se abusa del tópico. En los trabajos de Juan Vaccaro (Film-Historia, Universitat de Barcelona) y de Igor Barrenechea (Universidad del País Vasco) se nos intenta acercar al ser de ambas películas. El libro presenta también una lista, no exhaustiva, de películas chinas y japonesas que reflejan diversos aspectos de la historia de China y Japón en el siglo XX. Este volumen será de utilidad para aquellos que sientan interés por la cultura, la historia y la cinematografía de ambos países.

Three-photon absorption-induced fluorescence and optical limiting effects in a fluorene derivative

This paper reports on the steady-state fluorescence, three- photon absorption-induced fluorescence emission and subsequently induced optical limiting behaviour of a fluorene derivative with D-pi-D structural motifs. The lifetime of the steady-state fluorescence is 0.903 ns. Large optical limiting behaviour induced by 3PA has also been demonstrated, and the nonlinear absorption coefficient gamma derived from 3PA fitting curves is 5.92 x 10(-20) cm(3)/W-2 and the corresponding molecular 3PA cross-section sigma(3)' is 1.14 x 10(-76) cm(6) s(2).