Luminescence of heat-treated silicon-based polymers: promising materials for LED applications

A new strategy to obtain transparent, thermally stable, and formable photoluminescent materials for LED applications is presented. Starting from commercially available silicon-based polymers, luminescence properties are developed by means of simple heat treatment. Solid polymethylsilsesquioxane MK (Wacker-Besil^®PMS MK) and liquid poly(ureamethylvinyl)silazane Ceraset (Kion Ceraset^® PUVMS) were thermally treated between 200 and 700 °C for 2 h under Ar atmosphere. Photoluminescence properties were observed in all the samples. The structural rearrangements during thermal annealing were effective in order to red-shift the emission spectra of the untreated polymers to the visible range. The formation of dangling bonds and carbon sp², associated with the annealing procedure and confirmed by means of Electron Paramagnetic Resonance (EPR) spectroscopy and solid state Magic Angle Spinning NMR (MAS-NMR) contribute to the red-shift of the photoluminescence emissions of the polymers. After heat treatment at low temperatures (200, 300, and 400 °C), both the polymers show fluorescence in the UV range. While the polysiloxane reveals white luminescence after annealing at 500 and 600 °C, the polysilazane heat-treated at 500 °C exhibits emission in the blue-green range and is transparent. At higher temperatures the presence of free carbon counteracts the luminescence properties.     

Real-time interaction of virtual and physical objects in mixed reality applications

We present a real-time method for computing the mechanical interaction between real and virtual objects in an augmented reality environment. Using model order reduction methods we are able to estimate the physical behavior of deformable objects in real time, with the precision of a high-fidelity solver but working at the speed of a video sequence. We merge tools of machine learning, computer vision, and computer graphics in a single application to describe the behavior of deformable virtual objects allowing the user to interact with them in a natural way. Three examples are provided to test the performance of the method.     

A generalized reduced fluid dynamic model for flow fields and electrodes in redox flow batteries

High-dimensional models typically require a large computational overhead for multiphysics applications, which hamper their use for broad-sweeping domain interrogation. Herein, we develop a modeling framework to capture the through-plane fluid dynamic response of electrodes and flow fields in a redox flow cell, generating a computationally inexpensive two-dimensional (2D) model. We leverage a depth-averaging approach that also accounts for variations in out-of-plane fluid motion and departures from Darcy's law that arise from averaging across three-dimensions (3D). Our resulting depth-averaged 2D model successfully predicts the fluid dynamic response of arbitrary in-plane flow field geometries, with discrepancies of <5% for both maximum velocity and pressure drop. This corresponds to reduced computational expense, as compared to 3D representations (<1% of duration and 10% of RAM usage), providing a platform to screen and optimize a diverse set of cell geometries.     

Controlling Electrochemically Induced Volume Changes in Conjugated Polymers by Chemical Design: from Theory to Devices

Electrochemically induced volume changes in organic mixed ionic-electronic conductors (OMIECs) are particularly important for their use in dynamic microfiltration systems, biomedical machinery, and electronic devices. Although significant advances have been made to maximize the dimensional changes that can be accomplished by OMIECs, there is currently limited understanding of how changes in their molecular structures impact their underpinning fundamental processes and their performance in electronic devices. Herein, a series of ethylene glycol functionalized conjugated polymers is synthesized, and their electromechanical properties are evaluated through a combined approach of experimental measurements and molecular dynamics simulations. As demonstrated, alterations in the molecular structure of OMIECs impact numerous processes occurring during their electrochemical swelling, with sidechain length shortening decreasing the number of incorporated water molecules, reducing the generated void volumes and promoting the OMIECs to undergo different phase transitions. Ultimately, the impact of these combined molecular processes is assessed in organic electrochemical transistors, revealing that careful balancing of these phenomena is required to maximize device performance.     

Functional biodegradable protein-based matrices as a potential candidate for micronutrients and water supply

The excessive use of fertilizers in horticulture applications generates subsoil and groundwater contamination due to their high solubility. A possible solution to this problem is the incorporation of nutrients in biodegradable matrices, allowing nutrients to be released in a controlled manner depending on the needs of the crops. The principal objective of this work was the evaluation of the incorporation of different salts into soy protein-based matrices to develop devices that could release micronutrients in a controlled manner. Thus, the processability of matrices with different incorporated salts such as zinc sulfate heptahydrate (ZnSO₄·7H₂O), zinc sulfate monohydrate (ZnSO₄·H₂O), zinc carbonate (ZnCO₃), and zinc perchlorate (Zn(ClO₃)₂), as well as their integrity and functionality have been evaluated. Results show the great potential of soy protein-based matrices for the incorporation of micronutrients such as zinc. However, salt incorporation has a detrimental effect on the water uptake capacity of the matrices.     

P-score: a reputation bibliographic index that complements citation counts

Scientometrics - The notions of reputation and popularity in academia are critical for taking decisions on research grants, faculty position tenure, and research excellence awards. These notions...     

The role of MRI in prostate cancer: current and future directions

Magnetic Resonance Materials in Physics, Biology and Medicine - There has been an increasing role of magnetic resonance imaging (MRI) in the management of prostate cancer. MRI already plays an...     

A control architecture for continuous production processes based on industry 4.0: water supply systems application

Journal of Intelligent Manufacturing - Industry 4.0 (I4.0) brings together new disruptive technologies, increasing future factories’ productivity. Indeed, the control of production processes...