Important aspects of investigating optical excitations in semiconductors using a scanning transmission electron microscope

Since semiconductor structures are becoming smaller and smaller, the examination methods must also take this development into account. Optical methods have long reached their limits here, but small dimensions are also a challenge for electron beam techniques, especially when it comes to determining optical properties. In this paper, electron microscopic methods of investigating optical properties are discussed. Special attention is given to the physical limits and how to deal with them. We will cover electron energy loss spectrometry as well as cathodoluminescence spectrometry. We pay special attention to inelastic delocalisation, radiation damage, the Čerenkov effect, interference effects of optical excitations and higher diffraction orders on a grating analyser for the cathodoluminescence signal.     

Nanoscale Controlled Oxidation of Liquid Metals for Stretchable Electronics and Photonics

Liquid metals based on gallium have attracted considerable attention for soft and bioelectronics, thanks to their excellent combination of stretchability and conductivity. Nevertheless, owing to their large surface tension, these materials are notoriously difficult to pattern and shape into thin continuous films, or nanoscale 2D architectures, hindering practical use in systems with reduced dimensions. Herein, thanks to fine control in both substrate surface state and oxidation dynamics, a process for producing stretchable gallium-based conducting films with percolation down to 90 nm thickness is presented. By further combining this process with lithography, it is also demonstrated that the approach enables, for the first time, stable stretchable gallium-based optical metasurfaces with tunable resonance in the infrared. It is shown that oxygen partial pressure during evaporation determines the initial film percolation via an interplay between oxidation and dewetting. With this approach, conducting films with relative resistance change as low as 3% over 50% strain, with an excellent stability over 15k cycles are also demonstrated. Tunable soft optical metasurfaces with sub-micrometer feature sizes are also realized, paving the way toward a novel paradigm in soft electronics and photonics.     

Is contextual animation needed in multimedia learning games for children? An eye tracker study

The present study investigates affective-motivational, attention, and learning effects of unexplored emotional design manipulation: Contextual animation (animation of contextual elements) in multimedia learning game (MLGs) for children. Participants (N = 134; M_age = 9.25; Grades 3 and 4) learned either from an experimental version of the MLG with a high amount of contextual animation or from an identical MLG with no contextual animation (control). Children strongly preferred (χ² = 87.04, p < .001) and found the experimental version more attractive (p < .001, d = −1.11). No significant differences in overall enjoyment and learning outcomes were found. Attention differences, measured by dwell times and fixation durations, were small and reached only borderline significance (p = .035; d = −0.39). The implication is that contextual animation in MLG for children increases such instructional materials' attractiveness without compromising cognitive processes needed for learning; however, it does not lead to their higher instructional efficiency.     

Selective Aerobic Oxidation of Benzyl Alcohols with Palladium(0) Nanoparticles Suspension in Water

Catalysis Letters - This study concerns one of the rare applications of a suspension of palladium nanoparticles in water for oxidation reactions. The aqueous suspension containing well dispersed...     

Cone penetration tests in dry and saturated Ticino sand

Bulletin of Engineering Geology and the Environment - It is commonly assumed that dry and saturated sands exhibit similar cone resistance–relative density relationships. Some studies pointed...     

Feasibility of on-line speed policies in real-time systems

Real-Time Systems - We consider a real-time system where a single processor with variable speed executes an infinite sequence of sporadic and independent jobs. We assume that job sizes and relative...     

Soil Nitric Oxide Emissions from Nitrification and Denitrification

A silty loam soil treated with 1-allyl-2-thiourea as an inhibitor of autotrophic nitrification, and sulfide as an inhibitor of nitric oxide reductase in respiratory denitrification, was studied to evaluate the respective contribution of these two microbial processes to the nitric oxide (NO) flux from the soil. Soil samples were either unamended or amended with ammoniated fertilizer or biosolids from a wastewater treatment plant at an application rate of 100 lb-nitrogen∕acre. Water-filled pore space and temperature were maintained within respective ranges of 22 ± 2% and 22 ± 1°C. NO fluxes from unamended, chemically fertilized, and biosolids-amended soil samples increase in that order, and autotrophic nitrification accounts for 80, 84, and 92% of the NO flux, respectively. The suggested Jousset-Peirce index Ψ, which shows the contribution of respiratory denitrification with respect to heterotrophic nitrification and chemodenitrification, decreases by a factor of 3.3 and 5.6 from unamended to chemically fertilized soil samples and from unamended to biosolids-amended soil samples, respectively. An ancillary finding reveals the dramatic sensitivity of denitrification to the presence of sulfide.