Exceptional Microscale Plasticity in Amorphous Aluminum Oxide at Room Temperature

Oxide glasses are an elementary group of materials in modern society, but brittleness limits their wider usability at room temperature. As an exception to the rule, amorphous aluminum oxide (a-Al2O3) is a rare diatomic glassy material exhibiting significant nanoscale plasticity at room temperature. Here, it is shown experimentally that the room temperature plasticity of a-Al2O3 extends to the microscale and high strain rates using in situ micropillar compression. All tested a-Al2O3 micropillars deform without fracture at up to 50% strain via a combined mechanism of viscous creep and shear band slip propagation. Large-scale molecular dynamics simulations align with the main experimental observations and verify the plasticity mechanism at the atomic scale. The experimental strain rates reach magnitudes typical for impact loading scenarios, such as hammer forging, with strain rates up to the order of 1 000 s−1, and the total a-Al2O3 sample volume exhibiting significant low-temperature plasticity without fracture is expanded by 5 orders of magnitude from previous observations. The discovery is consistent with the theoretical prediction that the plasticity observed in a-Al2O3 can extend to macroscopic bulk scale and suggests that amorphous oxides show significant potential to be used as light, high-strength, and damage-tolerant engineering materials.Peer reviewe

An Open Source Classifier for Bed Mattress Signal in Infant Sleep Monitoring

Objective To develop a non-invasive and clinically practical method for a long-term monitoring of infant sleep cycling in the intensive care unit. Methods Forty three infant polysomnography recordings were performed at 1-18 weeks of age, including a piezo element bed mattress sensor to record respiratory and gross-body movements. The hypnogram scored from polysomnography signals was used as the ground truth in training sleep classifiers based on 20,022 epochs of movement and/or electrocardiography signals. Three classifier designs were evaluated in the detection of deep sleep (N3 state): support vector machine (SVM), Long Short-Term Memory neural network, and convolutional neural network (CNN). Results Deep sleep was accurately identified from other states with all classifier variants. The SVM classifier based on a combination of movement and electrocardiography features had the highest performance (AUC 97.6%). A SVM classifier based on only movement features had comparable accuracy (AUC 95.0%). The feature-independent CNN resulted in roughly comparable accuracy (AUC 93.3%). Conclusion Automated non-invasive tracking of sleep state cycling is technically feasible using measurements from a piezo element situated under a bed mattress. Significance An open source infant deep sleep detector of this kind allows quantitative, continuous bedside assessment of infant's sleep cycling.Peer reviewe

Synchrotron Section Topographic Study of Czochralski-Grown Silicon Wafers for Advanced Memory Circuits

Silicon wafers especially prepared to meet a customer's needs in the production of semiconductor memory circuits are studied with synchrotron section topography. A well‐defined uniform denuded zone below the surface with a width of 12 to 24 μm is observed. The concentration and the size of the oxygen‐related defects in the bulk are independent of the location along the crystal ingot, from which the wafer originates, and of that along the wafer diameter

Public libraries as a partner in digital innovation project:designing a virtual reality experience to support digital literacy

Abstract We introduce a project titled as Our Shared Virtual World which aims at increasing public libraries’ capability to provide knowledge on digital technology to general public. The practical goal of the project has been to produce a functional prototype of a virtual reality (VR) application that could be utilized freely in all the public libraries in Finland. In many countries worldwide, libraries’ role is expanding from providers of traditional books to providers of information technologies and related new forms of literacy, and this development provides the broader backdrop for the project. The contribution of the article is two-fold: First, we describe how an immersive VR application can be collaboratively developed within this specific research context, namely within a network of public libraries, and introduce the tangible outcome of the project, the VR application called Forest Elf. Secondly, we scrutinize how results of such a design work can be sustained over time: through participatory design (PD), we aimed at creating conditions which would enable public libraries to continue developing and using the artefact also after the project. We provide insights on how to tackle the challenge of research prototypes ending up being abandoned, and what factors in the context of library partnership support or hamper sustainable digital innovation — digital innovation that is inclusive and equitable but also has a long-lasting impact

Roll-to-roll manufacturing of disposable surface-enhanced Raman scattering (SERS) sensors on paper based substrates

We present two cost-effective routes for roll-to-roll (R2R) manufacturing of silver nanoparticle based surface-enhanced Raman scattering (SERS) active substrates on paper utilizing either inkjet printing or liquid flame spray (LFS) nanoparticle deposition. Paper is cost-effective, renewable, recyclable, and biodegradable that can easily be disposed after the SERS analysis. Paper based substrates can have a strong luminescence that can overshadow the rather weak SERS signal. Two solutions are presented here that solve the luminescence issue of the base paper substrate. A full silver coverage by inkjet printing or alternatively a simple flexography carbon coating can suppress the background luminescence allowing a reliable SERS characterization. The detection limit of the sample analyte crystal violet was 100 nM corresponding to 100 fmol in a 1 µl sample volume. These approaches can provide a cost-effective route towards disposable, point-of-care SERS active substrates.publishedVersionPeer reviewe