Critical Drug Loss Induced by Silicone and Polyurethane Implantable Catheters in a Simulated Infusion Setup with Three Model Drugs

Silicone and polyurethane are biocompatible materials used for the manufacture of implantable catheters, but are known to induce drug loss by sorption, causing potentially important clinical consequences. Despite this, their impact on the drugs infused through them is rarely studied, or they are studied individually and not part of a complete infusion setup. The aim of this work was to experimentally investigate the drug loss that these devices can cause, on their own and within a complete infusion setup. Paracetamol, diazepam, and insulin were chosen as models to assess drug sorption. Four commonly used silicone and polyurethane catheters were studied independently and as part of two different setups composed of a syringe, an extension set, and silicone or polyurethane implantable catheter. Simulated infusion through the catheter alone or through the complete setup were tested, at flowrates of 1 mL/h and 10 mL/h. Drug concentrations were monitored by liquid chromatography, and the silicone and polyurethane materials were characterized by ATR-IR spectroscopy and Zeta surface potential measurements. The losses observed with the complete setups followed the same trend as the losses induced individually by the most sorptive device of the setup. With the complete setups, no loss of paracetamol was observed, but diazepam and insulin maximum losses were respectively of 96.4 ± 0.9% and 54.0 ± 5.6%, when using a polyurethane catheter. Overall, catheters were shown to be the cause of some extremely high drug losses that could not be countered by optimizing the extension set in the setup.

Cross-field optoelectronic modulation via inter-coupled ferroelectricity in 2D In2Se3

The ability to couple the in-plane (IP) and out-of-plane (OOP) dipole polarizations in ferroelectric In2Se3 makes it a promising material for multimodal memory and optoelectronic applications. Herein, we experimentally demonstrate the cross-field optoelectronic modulation in In2Se3 based field-effect devices. Surface potential measurements of In2Se3 based devices directly reveal the bidirectional dipole locking following high gate voltage pulses. The experimental evidence of hysteretic change in the IP electrical field facilitating a nonvolatile memory switch, was further explored by performing photocurrent measurements. Fabricated photodetectors presented multilevel photocurrent characteristics showing promise for nonvolatile memory and electro-optical applications.

Circuit Analysis of Ionizing Surface Potential Measurements of Electrolyte Solutions

Surface potential measurement values of the gas-liquid interface can be ambiguous despite the numerous electrochemical approaches used for quantification of the reported values. Calibration and normalization methods can be undefined, which often undermines the robustness of the reported values. Surface potential instrumentation and data interpretation also varies significantly across literature. Here, we propose a circuit model for an ionizing surface potential method based on the alpha decay of a radioactive americium-241 electrode. We evaluate the robustness of the circuit model for quantifying the surface potential at the air-aqueous interface. We then show successful validation of our circuit model through determination of the surface tension of the air-electrolyte interface with comparison to respective surface tension literature values. This validation reveals the reliability of surface potential measurements using the americium-241 ionizing method.<br>

Circuit Analysis of Ionizing Surface Potential Measurements of Electrolyte Solutions

Surface potential measurement values of the gas-liquid interface can be ambiguous despite the numerous electrochemical approaches used for quantification of the reported values. Calibration and normalization methods can be undefined, which often undermines the robustness of the reported values. Surface potential instrumentation and data interpretation also varies significantly across literature. Here, we propose a circuit model for an ionizing surface potential method based on the alpha decay of a radioactive americium-241 electrode. We evaluate the robustness of the circuit model for quantifying the surface potential at the air-aqueous interface. We then show successful validation of our circuit model through determination of the surface tension of the air-electrolyte interface with comparison to respective surface tension literature values. This validation reveals the reliability of surface potential measurements using the americium-241 ionizing method.<br>

Nanoscale Ring-Shaped Conduction Channels with Memristive Behavior in BiFeO3 Nanodots

Nanoscale ring-shaped conduction channels with memristive behavior have been observed in the BiFeO3 (BFO) nanodots prepared by the ion beam etching. At the hillside of each individual nanodot, a ring-shaped conduction channel is formed. Furthermore, the conduction channels exhibit memristive behavior, i.e., their resistances can be continuously tuned by the applied voltages. More specifically, a positive (negative) applied voltage reduces (increases) the resistance, and the resistance continuously varies as the repetition number of voltage scan increases. It is proposed that the surface defects distributed at the hillsides of nanodots may lower the Schottky barriers at the Pt tip/BFO interfaces, thus leading to the formation of ring-shaped conduction channels. The surface defects are formed due to the etching and they may be temporarily stabilized by the topological domain structures of BFO nanodots. In addition, the electron trapping/detrapping at the surface defects may be responsible for the memristive behavior, which is supported by the surface potential measurements. These nanoscale ring-shaped conduction channels with memristive behavior may have potential applications in high-density, low-power memory devices.