71 research outputs found
Increasing Out of Bed the Day of Surgery Documentation for Post-Op Total Hip & Knee Replacements
https://jdc.jefferson.edu/nurseresidencyposters/1000/thumbnail.jp
AlScN: A III-V semiconductor based ferroelectric
Ferroelectric switching is unambigiously demonstrated for the first time in a
III-V semiconductor based material: AlScN -- A discovery which could help to
satisfy the urgent demand for thin film ferroelectrics with high performance
and good technological compatibility with generic semiconductor technology
which arises from a multitude of memory, micro/nano-actuator and emerging
applications based on controlling electrical polarization. The appearance of
ferroelectricity in AlScN can be related to the continuous distortion of the
original wurtzite-type crystal structure towards a layered-hexagonal structure
with increasing Sc content and tensile strain, which is expected to be
extendable to other III-nitride based solid solutions. Coercive fields which
are systematically adjustable by more than 3 MV/cm, high remnant polarizations
in excess of 100 \mu C/cm which constitute the first experimental estimate
of the previously inaccessible spontaneous polarization in a III-nitride based
material, an almost ideally square-like hysteresis resulting in excellent
piezoelectric linearity over a wide strain interval from -0.3% to +0.4% as well
as a paraelectric transition temperature in excess of 600{\deg}C are confirmed.
This intriguing combination of properties is to our knowledge as of now
unprecedented in the field of polycrystalline ferroelectric thin films and
promises to significantly advance the commencing integration of ferroelectric
functionality to micro- and nanotechnology, while at the same time providing
substantial insight to one of the central open questions of the III-nitride
semiconductors - that of their actual spontaneous polarization
Al1−xScxN Thin Films at High Temperatures: Sc-Dependent Instability and Anomalous Thermal Expansion
Ferroelectric thin films of wurtzite-type aluminum scandium nitride (Al1-xScxN) are promising candidates for non-volatile memory applications and high-temperature sensors due to their outstanding functional and thermal stability exceeding most other ferroelectric thin film materials. In this work, the thermal expansion along with the temperature stability and its interrelated effects have been investigated for Al1-xScxN thin films on sapphire Al2O3(0001) with Sc concentrations x (x = 0, 0.09, 0.23, 0.32, 0.40) using in situ X-ray diffraction analyses up to 1100 °C. The selected Al1-xScxN thin films were grown with epitaxial and fiber textured microstructures of high crystal quality, dependent on the choice of growth template, e.g., epitaxial on Al2O3(0001) and fiber texture on Mo(110)/AlN(0001)/Si(100). The presented studies expose an anomalous regime of thermal expansion at high temperatures >~600 °C, which is described as an isotropic expansion of a and c lattice parameters during annealing. The collected high-temperature data suggest differentiation of the observed thermal expansion behavior into defect-coupled intrinsic and oxygen-impurity-coupled extrinsic contributions. In our hypothesis, intrinsic effects are denoted to the thermal activation, migration and curing of defect structures in the material, whereas extrinsic effects describe the interaction of available oxygen species with these activated defect structures. Their interaction is the dominant process at high temperatures >800 °C resulting in the stabilization of larger modifications of the unit cell parameters than under exclusion of oxygen. The described phenomena are relevant for manufacturing and operation of new Al1-xScxN-based devices, e.g., in the fields of high-temperature resistant memory or power el. appl
Strategies to improve the dietary quality of Supplemental Nutrition Assistance Program (SNAP) beneficiaries: an assessment of stakeholder opinions
Objective: To examine the opinions of stakeholders on strategies to improve dietary quality of Supplemental Nutrition Assistance Program (SNAP) participants. Design: Participants answered a thirty-eight-item web-based survey assessing opinions and perceptions of SNAP and programme policy changes. Setting: USA. Subjects: Survey of 522 individuals with stakeholder interest in SNAP, conducted in October through December 2011. Results: The top three barriers to improving dietary quality identified were: (i) unhealthy foods marketed in low-income communities; (ii) the high cost of healthy foods; and (iii) lifestyle challenges faced by low-income individuals. Many respondents (70 %) also disagreed that current SNAP benefit levels were adequate to maintain a healthy diet. Stakeholders believed that vouchers, coupons or monetary incentives for purchasing healthful foods might have the greatest potential for improving the diets of SNAP participants. Many respondents (78 %) agreed that sodas should not be eligible for purchases with SNAP benefits. More than half (55 %) believed retailers could easily implement such restrictions. A majority of respondents (58 %) agreed that stores should stock a minimum quantity of healthful foods in order to be certified as a SNAP retailer, and most respondents (83 %) believed that the US Department of Agriculture should collect data on the foods purchased with SNAP benefits. Conclusions: Results suggest that there is broad stakeholder support for policies that align SNAP purchase eligibility with national public health goals of reducing food insecurity, improving nutrition and preventing obesity
Thin-Film-Based SAW Magnetic Field Sensors
In this work, the first surface acoustic-wave-based magnetic field sensor using thin-film AlScN as piezoelectric material deposited on a silicon substrate is presented. The fabrication is based on standard semiconductor technology. The acoustically active area consists of an AlScN layer that can be excited with interdigital transducers, a smoothing SiO2 layer, and a magnetostrictive FeCoSiB film. The detection limit of this sensor is 2.4 nT/Hz at 10 Hz and 72 pT/Hz at 10 kHz at an input power of 20 dBm. The dynamic range was found to span from about ±1.7 mT to the corresponding limit of detection, leading to an interval of about 8 orders of magnitude. Fabrication, achieved sensitivity, and noise floor of the sensors are presented
Ultrasensitive Magnetoelectric Sensing System for pico-Tesla MagnetoMyoGraphy
MagnetoMyoGraphy (MMG) with superconducting quantum interference devices (SQUIDs) enabled the measurement of very weak magnetic fields (femto to pico Tesla) generated from the human skeletal muscles during contraction. However, SQUIDs are bulky, costly and require working in a temperature-controlled environment, limiting wide-spread clinical use. We introduce a low-profile magnetoelectric (ME) sensor with analog frontend circuitry that has sensitivity to measure pico-Tesla MMG signals at room temperature. It comprises magnetostrictive and piezoelectric materials, FeCoSiB/AlN. Accurate device modelling and simulation are presented to predict device fabrication process comprehensively using the finite element method (FEM) in COMSOL Multiphysics®. The fabricated ME chip with its readout circuit was characterized under a dynamic geomagnetic field cancellation technique. The ME sensor experiment validate a very linear response with high sensitivities of up to 378 V/T driven at a resonance frequency of fres = 7.76 kHz. Measurements show the sensor limit of detections of down to 175 pT/Hz at resonance, which is in the range of MMG signals. Such a small-scale sensor has the potential to monitor chronic movement disorders and improve the end-user acceptance of human-machine interfaces
TensorFlow training via genetic algorithm for the B.L.I.T.Z.K.R.I.E.G Project.
College of Engineering; Computer Engineering Department; Advisor: Dr. Buren Wells; Date: May 5, 2020; Pages: 44 p.; This paper was submitted during the COVID-19 Pandemic of 2020. UAH went to remote learning in the middle of March 2020 to the end of the Spring Semester
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