Extracorporeal ultrasound exposure by the low-frequency acoustic amplitude-modulated signal on a ureteral stent for preventing its incrustation: experimental determination of optimal application points

Introduction. Incrustation and biofilms formation on the surface of ureteral stents are still the most significant complications of internal drainage of the upper urinary tract. There are much researchers conducted to combat these complications. The lack of a solution to this problem affects the ultimate results of treatment and economic losses. The issue of impact by physical methods on the ureteral stent, particularly the use of extracorporeal ultrasound acoustic exposure remains, promising and poorly covered.Purpose of the study. To determine the optimal application points of extracorporeal acoustic exposure by the low-frequency ultrasonic amplitude-modulated signal on a ureteral stent in an experiment.Materials and methods. The original device was designed. The main principle of its operation is the generation of an amplitude-modulated ultrasonic signal in two modes: pulsed and permanent. A sexually mature mongrel dog was an experimental animal. The ureteral stent was placed by laparotomy and cystotomy. Intraoperatively, the emitter of the developed device was applied to the skin of the animal, according to the previously indicated topographic and anatomical landmarks. At the same time, an ultrasonic wave noise analyzer was applied through the laparotomy wound to the appropriate level of the ureter. Measurements of ultrasound intensity indicators were performed three times in two operating modes of the device.Results. Pulsed mode: for the ureteral upper third, the highest ultrasonic intensity (123.67 dB) was achieved along the posterior axillary line. For the ureteral middle third, the best ultrasound intensity (115 dB) was obtained by the posterior axillary line. For the ureteral lower third, the highest ultrasound intensity (113.67 dB) was noted along the middle axillary line.Permanent mode: the best ultrasonic intensity in the projection of the ureteral upper, middle, and lower thirds was achieved along the posterior axillary line and was 118.67 dB, 117 dB and 116.67 dB, accordingly. However, there was an excessive heat effect, manifested by hyperemia and hyperthermia of the animal's skin, fascicular muscle contractions during the instrument functioned in the permanent mode, which can potentially lead to thermal burns and intolerance to the procedure.Conclusion. The pulsed mode of the device function is most safe. The optimal application points of the instrument emitter for the ureteral upper and middle thirds is the posterior axillary line, and for the ureteral lower third is the middle axillary line

The effect of ultrasonic vibrations with superimposed low-frequency modulation on the mechanical, tribological properties and structure of a multicomponent polymer composite

One of the tasks of polymer materials science is to study the possibilities of improving the complex of elastic-strength characteristics and tribological properties of polymer composite materials by improving the manufacturing technology. In this paper, the influence of ultrasonic vibrations with a frequency of 17 kHz with a low-frequency vibration with a frequency of 100 Hz during synthesis on the properties and structure of a multicomponent polymer composite material of the KVN-3 trademark is considered. The result of the research, it is found that the influence of the technological mode of pressing, consisting in the combined effect of ultrasonic vibrations with frequency and low-frequency vibration during the synthesis of KVN-3, makes it possible to increase the complex of elastic-mechanical characteristics: tensile strength by 3 %, elongation by 6 %, modulus of elasticity by 10 %, hardness by 2 %, compared to the industrial manufacturing method, as well as to reduce the intensity of mass wear by 68 % and the coefficient of friction by 3 %. The structure of polymer composite materials after different technological pressing modes is examined. The fibrillar structure of the polymer matrix after the technological regime with the influence of ultrasonic vibrations and low-frequency modulation becomes finer and more uniform

Flexible HfO2_2-based ferroelectric memristor

The development of the next generation of flexible electronics for biomedical applications requires the implementation of flexible active elements, potentially microcontrollers. The further step in this direction includes the development of devices for data processing directly on-chip, in particular, devices for neuromorphic computing. One of the key elements put forward within this paradigm is the memristor—the device emulating the plasticity of biological synapses. Due to the internal temporal dynamics of conductance, second-order memristors exhibit the most natural emulation of a biological synapse. Among different types of second-order memristors, ferroelectric memristors show the best cell-to-cell and cycle-to-cycle reproducibility. Here, we demonstrate a flexible ferroelectric second-order memristor on a mica substrate based on the 5-nm-thick polycrystalline Hf$_{0.5}$Zr$_{0.5}$O$_2$ film. The conductance (synaptic weight) modulation with $_{OFF}/_{ON}$ ratio ∼20 is achieved via the gradual switching of the ferroelectric domains affecting the potential barrier in the structure. The devices demonstrate high reproducibility and various synaptic functionalities, including paired-pulse potentiation and paired-pulse depression. Functional properties persist both during static bending and after more than 100 bending cycles with a radius down to 1 cm