Abstract A dual-wavelength 532/1064 nm optoacoustic (OA) imaging system allows 3D visualizations of arteriovenous anastomoses (AVAs) with an acoustic spatial resolution (50 µ m) at depths of up to 2 mm in vivo in rabbit ears. Both structural and spectral information from the OA data are employed to analyze the anatomical locations of the blood vessels and to distinguish between veins and arteries in the zone of their confluence. The OA monitoring of a rabbit ear under temperature-induced (43 °C/15 °C) shunting demonstrated the potential of the technique for the monitoring of functional arteriovenous anastomosis.
In this work, we discuss the results of investigation of potential distribution instabilities in undoped AlGaN/GaN HEMTs and SiC transistor (FET) structures due to charge changes on the structure surface. An analysis of the state effects influence in the top layer of a passivated silicon nitride film reveals the possibility of the "memory effect" appearance due to electrons tunneling from an active area to different states in the silicon nitride film and AlGaN layer. All considerations are followed by device characterization. A technological process for silicon nitride film deposition and a precision method of hydrogen bond concentration measurement by FTIR were developed to carry out experiments with a high accuracy.
In this study, we have developed a biomorphic artificial intelligence system for pattern recognition tasks with adaptive error correction. The system imitates the process of hierarchical information processing inherent in living systems, for example, information processing in the visual cortex of the brain. Also, one of the properties that the developed system has is the correction of errors accumulated in the process of interaction with the outside world.
Our work was devoted to the experimental comparison of two ultra-wideband detectors based on PVDF piezofilms of different thickness demonstrating different quality of optoacoustic imaging of vessels in tumor and normal tissues.
Tumor microvascular responses may provide a sensitive readout indicative of radiation therapy efficacy, its time course and dose dependencies. However, direct high-resolution observation and longitudinal monitoring of large-scale microvascular remodeling in deep tissues remained challenging with the conventional microscopy approaches. We report on a non-invasive longitudinal study of morphological and functional neovascular responses by means of scanning optoacoustic (ОА) microangiography. In vivo imaging of CT26 tumor response to a single irradiation at varying dose (6, 12, and 18 Gy) has been performed over ten days following treatment. Tumor oxygenation levels were further estimated using diffuse optical spectroscopy (DOS) with a contact fiber probe. OA revealed the formation of extended vascular structures on the whole tumor scale during its proliferation, whereas only short fragmented vascular regions were identified following irradiation. On the first day post treatment, a decrease in the density of small (capillary-sized) and medium-sized vessels was revealed, accompanied by an increase in their fragmentation. Larger vessels exhibited an increase in their density accompanied by a decline in the number of vascular segments. Short-lasting response has been observed after 6 and 12 Gy irradiations, whereas 18 Gy treatment resulted in prolonged responses, up to the tenth day after irradiation. DOS measurements further revealed a delayed increase of tumor oxygenation levels for 18 Gy irradiations, commencing on the sixth day post treatment. The ameliorated oxygenation is attributed to diminished oxygen consumption by inhibited tumor cells but not to the elevation of oxygen supply. This work is the first to demonstrate the differential (size-dependent) nature of vascular responses to radiation treatments at varying doses in vivo. The OA approach thus facilitates the study of radiation-induced vascular changes in an unperturbed in vivo environment while enabling deep tissue high-resolution observations at the whole tumor scale.
