Insulator-to-metal transition of SrTiO3:Nb single crystal surfaces induced by Ar+ bombardment

In this paper, the effect of Ar+ bombardment of SrTiO3:Nb surface layers is investigated on the macro- and nanoscale using surface-sensitive methods. After bombardment, the stoichiometry and electronic structure are changed distinctly leading to an insulator-to-metal transition related to the change of the Ti "d" electron from d0 to d1 and d2. During bombardment, conducting islands are formed on the surface. The induced metallic state is not stable and can be reversed due to a redox process by external oxidation and even by self-reoxidation upon heating the sample to temperatures of 300{\deg}C.Comment: 4 pages, 4 figure

Teacher Challenges to Implement Engineering Design in Secondary Technology Education (Third in a Three Part Series)

This descriptive study examined the current status of technology education teacher practices with respect to engineering design. This article is the third article in a three-part series presenting the results of this study. The first article in the series titled Examination of Engineering Design Curriculum Content highlighted the research findings regarding engineering design curriculum content delivered by technology education teachers. The second article in the series titled Examination of Assessment Practices for Engineering Design Projects in Secondary Technology Education reported technology education teachers’ assessment practices when implementing engineering design projects in the classroom. The sample for this study was drawn from the current International Technology Education Association (ITEA) membership database. This article will present the research findings that identified challenges faced by technology educators when seeking to implement engineering design

Examination of Assessment Practices for Engineering Design Projects in Secondary Education (First in a Three Part Series)

The following descriptive study was designed to determine the national status of secondary technology education curriculum content and assessment practices as they relate to engineering design. The results of this study were divided into a three-part article series. Although this study focused on the larger construct of the national status of the infusion of engineering design into technology education, three separate sub-constructs emerged. The three sub-constructs were: a) status of engineering design curriculum content; b) the status of assessment practices of engineering design projects, and c) what selected challenges are identified by secondary technology educators in teaching engineering design

Examination of Assessment Practices for Engineering Design Projects in Secondary Education (Part 1)

The following descriptive study was designed to determine the national status of secondary technology education curriculum content and assessment practices as they relate to engineering design. The results of this study were divided into a three-part article series. Although this study focused on the larger construct of the national status of the infusion of engineering design into technology education, three separate sub-constructs emerged. The three sub-constructs were: a) status of engineering design curriculum content; b) the status of assessment practices of engineering design projects, and c) what selected challenges are identified by secondary technology educators in teaching engineering design

Examination of Assessment Practices for Engineering Design Projects in Secondary Education (Part 1)

The following descriptive study was designed to determine the national status of secondary technology education curriculum content and assessment practices as they relate to engineering design. The results of this study were divided into a three-part article series. Although this study focused on the larger construct of the national status of the infusion of engineering design into technology education, three separate sub-constructs emerged. The three sub-constructs were: a) status of engineering design curriculum content; b) the status of assessment practices of engineering design projects, and c) what selected challenges are identified by secondary technology educators in teaching engineering design

Transport limits in defect-engineered LaAlO3/SrTiO3 bilayers

The electrical properties of the metallic interface in LaAlO3/SrTiO3 (LAO/STO) bilayers are investigated with focus on the role of cationic defects in thin film STO. Systematic growth-control of the STO thin film cation stoichiometry (defect-engineering) yields a relation between cationic defects in the STO layer and electronic properties of the bilayer-interface. Hall measurements reveal a stoichiometry-effect primarily on the electron mobility. The results indicate an enhancement of scattering processes in as-grown non-stoichiometric samples indicating an increased density of defects. Furthermore, we discuss the thermodynamic processes and defect-exchange reactions at the LAO/STO-bilayer interface determined in high temperature equilibrium. By quenching defined defect states from high temperature equilibrium, we finally connect equilibrium thermodynamics with room temperature transport. The results are consistent with the defect-chemistry model suggested for LAO/STO interfaces. Moreover, they reveal an additional healing process of extended defects in thin film STO

In Vivo Time- Resolved Microtomography Reveals the Mechanics of the Blowfly Flight Motor

Dipteran flies are amongst the smallest and most agile of flying animals. Their wings are driven indirectly by large power muscles, which cause cyclical deformations of the thorax that are amplified through the intricate wing hinge. Asymmetric flight manoeuvres are controlled by 13 pairs of steering muscles acting directly on the wing articulations. Collectively the steering muscles account for <3% of total flight muscle mass, raising the question of how they can modulate the vastly greater output of the power muscles during manoeuvres. Here we present the results of a synchrotron-based study performing micrometre-resolution, time-resolved microtomography on the 145 Hz wingbeat of blowflies. These data represent the first four-dimensional visualizations of an organism's internal movements on sub-millisecond and micrometre scales. This technique allows us to visualize and measure the three-dimensional movements of five of the largest steering muscles, and to place these in the context of the deforming thoracic mechanism that the muscles actuate. Our visualizations show that the steering muscles operate through a diverse range of nonlinear mechanisms, revealing several unexpected features that could not have been identified using any other technique. The tendons of some steering muscles buckle on every wingbeat to accommodate high amplitude movements of the wing hinge. Other steering muscles absorb kinetic energy from an oscillating control linkage, which rotates at low wingbeat amplitude but translates at high wingbeat amplitude. Kinetic energy is distributed differently in these two modes of oscillation, which may play a role in asymmetric power management during flight control. Structural flexibility is known to be important to the aerodynamic efficiency of insect wings, and to the function of their indirect power muscles. We show that it is integral also to the operation of the steering muscles, and so to the functional flexibility of the insect flight motor

Age estimation during the blow fly intra-puparial period: a qualitative and quantitative approach using micro-computed tomography

© The Author(s) 2017. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The attached file is the published version of the article