Unconventional gallium oxide nanowires

Zigzag and helical beta-Ga(2)O(3) one-dimensional nanostructures were produced by thermal evaporation of gallium oxide in the presence of gallium nitride. High-resolution TEM analysis indicates that each individual zigzag nanostructure has a periodic arrangement of three distinct blocks: two structurally perfect blocks mirrored with respect to each other on the (002) plane, and one stacking-fault-rich block sandwiched between them. In a zigzag nanostructure, the growth orientation of a beta-Ga(2)O(3) crystal changes alternately in three blocks. The zigzag nanostructure as a whole has the [001] axial direction. In addition to zigzag nanostructures, single-crystalline helical nanowires were also obtained.     

Field nanoemitters: ultrathin BN nanosheets protruding from Si3N4 nanowires

Field emitters in nanoscale are important in micro/nanoelectronic devices. Here, we report a large scale synthesis and effective field emission of field nanoemitters. The integrated nanostructures of ultrathin BN nanosheets aligned on Si3N4 nanowires are prepared through a two-stage process. Si3N4 nanowires were previously synthesized through heating Si powder at 1500 degrees C under a N2 atmosphere. Ultrathin BN nanosheets were then deposited on Si3N4 nanowires by heating a homemade B-N-O precursor under a N2/NH3 atmosphere. The as-prepared nanofilaments act as cold electron emitters displaying excellent field emission performance owing to the untrathin and sharp edges of the protruding BN nanosheets.     

Semiconductor nanocrystals photosensitize C60 crystals

Semiconductor nanocrystals (SCNCs) made of CdSe, CdTe, and InP are used to photosensitize needlelike C(60) crystals. The photocurrent is increased by up to 3 orders of magnitude as compared with C(60) crystals without SCNCs. The photocurrent spectrum can be tuned precisely by the SCNC size and material, rendering the SCNC-functionalized C(60) crystals an excellent material for spectrally tuneable photodetectors. We explain the increased photocurrent as a result of photoexcited electrons transferring from the SCNCs to the C(60) crystals and causing photoconductivity, while the complementary holes remain trapped in the SCNCs.     

Project proposal for the investigation of particle-stabilised emulsions and foams by microgravity experiments

The utilisation of particle-surfactants nanostructures as stabilising agents represents today the technologic and scientific frontier in the stabilisation of liquid films in emulsion and foams. This topic will be addressed by the proposal STEFAN (STabilisation of Emulsions and FoAms by Nanoparticles), proposed by European groups in the framework of the ESA AO-2004 for Life and Physical Sciences and Applied Research projects Similarly to what can be observed for surfactant-stabilised emulsions and foams, microgravity provides ideal conditions for the investigation of the hierarchy of involved objects: interfacial layer, liquid film, dispersed systems foam or emulsion. Microgravity experiments are planned by refurbishing the Experimental Container FASES for the ISS Fluid Science Laboratory and the facility FASTER for the European Drawer Rack, already under development in existing research programmes. Here the scientific guidelines of the project are presented together with examples and preliminary results on the effect of nano-particle-surfactant structures adsorbed at liquid interfaces. First experimental results have been achieved for particle monolayers at the water/air interface and a thermodynamic model was derived to describe the obtained surface pressure-area isotherms.     

Power Dissipation in Spintronic Devices Out of Thermodynamic Equilibrium

Quantum limits of power dissipation in spintronic computing are estimated. A computing element composed of a single electron in a quantum dot is considered. Dynamics of its spin due to external magnetic field and interaction with adjacent dots are described via the Bloch equations. Spin relaxation due to magnetic noise from various sources is described as coupling to a reservoir. Resulting dissipation of energy is calculated and is shown to be much less than the thermal limit, ∼kT per bit, if the rate of spin relaxation is much slower than the switching rate. Clues on how to engineer an energy efficient spintronic device are provided.     

The effect of Fe on magnetic moment of electrodeposited CoFe alloys—Experimental study and analytical model

The effect of Fe³⁺ concentration on saturation magnetic flux density (B_s) of electrodeposited Co_40-44Fe_60-56 films was investigated. The results show that if the conditions at the electrochemical interface for nucleation/precipitation of iron(III) hydroxide (Fe(OH)₃) are reached, the B_s of electrodeposited Co_40-44Fe_60-56 films quickly decreases as a result of the Fe(OH)₃ incorporation into deposit. These conditions are discussed as a function of the solution formulation (pH) and the parameters of electrodeposition process (current density, current efficiency, diffusion layer thickness) and a simple analytical model is developed qualitatively describing the hydroxide incorporation phenomenon and resulting decrease in B_s of Co_40-44Fe_60-56 films.     

Optimizing the NIR Fluence Threshold for Nanobubble Generation by Controlled Synthesis of 10–40 nm Hollow Gold Nanoshells

The laser fluence to trigger nanobubbles around hollow gold nanoshells (HGN) with near infrared light is examined through systematic modification of HGN size, localized surface plasmon resonance (LSPR), HGN concentration, and surface coverage. Improved temperature control during silver template synthesis provides monodisperse, silver templates as small as 9 nm. 10 nm HGN with <2 nm shell thickness are prepared from these templates with a range of surface plasmon resonances from 600 to 900 nm. The fluence of picosecond near infrared (NIR) pulses to induce transient vapor nanobubbles decreases with HGN size at a fixed LSPR wavelength, unlike solid gold nanoparticles of similar dimensions that require an increased fluence with decreasing size. Nanobubble generation causes the HGN to melt with a blue shift of the LSPR. The nanobubble threshold fluence increases as the irradiation wavelength moves off the nanoshell LSPR. Surface treatment does not influence the threshold fluence. The threshold fluence increases with decreasing HGN concentration, suggesting that light localization through multiple scattering plays a role. The nanobubble threshold to rupture liposomes is four times smaller for 10 nm than for 40 nm HGN at a given LSPR, allowing us to use HGN size, LSPR, laser wavelength and fluence to control nanobubble generation.     

Why We Distort in Self‐Report: Predictors of Self‐Report Errors in Video Game Play

Using Cognitive Dissonance and Balance Theory, this study investigates factors that predict how and why MMO players inaccurately report their game playing time. It was hypothesized that players belonging to categories other than the stereotypical game player (e.g. younger, less educated, male) would be likely to underreport playing time. It was also hypothesized that those players who held less positive attitudes toward the game would be more likely to underreport their playing time. Comparing people's self‐reported weekly usage of an MMO, EverQuest II, with their actual average weekly usage of the game, data showed that age, education, lack of enjoyment playing the game, and lack of an online sense of community predicted greater levels of underreporting.     

Object segmentation in cluttered and visually complex environments

Object segmentation is essential for systems that acquire object models online for robotic grasping. However, it remains a major technical challenge in visually complex and uncontrolled environments. Segmentation algorithms that rely on image features alone can perform poorly under certain lighting conditions, or if the object and the background have similar appearance. In parallel, known object segmentation algorithms that rely exclusively on three dimensional (3D) geometric data are derived under strong assumptions about the geometry of the scene. A promising approach to performing object segmentation is to use a combination of appearance and 3D features. In this paper, an object segmentation algorithm is presented that combines multiple appearance and geometric cues. The segmentation is formulated as a binary labeling problem. The Conditional Random Fields (CRF) framework is used to model the conditional probability of the labeling given the appearance and geometric data. The maximum a posteriori estimation of the labeling is obtained by minimizing the energy function corresponding to the CRF using graph cuts. A simple and efficient method for initializing the proposed algorithm is also presented. Experimental results have demonstrated the effectiveness of the proposed algorithm.