Effects of Dual-Frequency Ultrasound-Assisted Thawing Technology on Thawing Rate, Quality Properties and Microstructure of Large Yellow Croaker (Pseudosciaena crocea)

This research evaluated the effects of dual-frequency ultrasound-assisted thawing (UAT) on the thawing time, physicochemical quality, water-holding capacity (WHC), microstructure, and moisture migration and distribution of large yellow croaker. Water thawing (WT), refrigerated thawing (RT), and UAT (single-frequency: 28 kHz (SUAT-28), single-frequency: 40 kHz (SUAT-40), dual-frequency: 28 kHz and 40 kHz (DUAT-28/40)) were used in the current research. Among them, the DUAT-28/40 treatment had the shortest thawing time, and ultrasound significantly improved the thawing rate. It also retained a better performance from the samples, such as color, texture, water-holding capacity and water distribution, and inhibited disruption of the microstructure. In addition, a quality property analysis showed that the pH, total volatile basic nitrogen (TVB-N), and K value were the most desirable under the DUAT-28/40 treatment, as well as this being best for the flavor of the samples. Therefore, DUAT-28/40 treatment could be a possible thawing method because it improves the thawing rate and maintains the quality properties of large yellow croaker.

Changes in the microcirculation of the oral mucosa in post-COVID-19 patients not receiving anti-coagulant therapy

Introduction. The outbreak of a new coronavirus infection has become a challenge for the global health system. The COVID-19 infection is directly related to various disorders of the cardiovascular system, including the microcirculatory bed, caused by thrombotic events and deteriorations of blood rheology. Aims. The paper reports on the results of a study of Doppler sonographic parameters changes in patients with a novel coronavirus infection over the past 6 months. Materials and methods. We assessed the oral mucosa microcirculation in three segments using the high-frequency ultrasound dopple-rography. Results. We recorded the linear and volumetric blood flow rates and the Gosling and Purselo indexes in the course of our work. When comparing the obtained average statistical parameters of blood flow velocity, the linear and volumetric blood flow rates in patients of both groups were found to be lain in the same range and the mean values of Vas, Vam, Qas were equal. The mean values of the Purselo resistance index were closer to 1,0 in patients with COVID-19, and the values of the Gosling pulsation index (PI) were on average 53.3 % higher than in the control group. Conclusion. We evaluated the screening capabilities and potential of high-frequency ultrasound dopplerography for use in patients of different age groups and different somatic status.

The potential of high-frequency ultrasound Dopplerography in the assessment of microcirculatory disorders in post-COVID-19 patients with a cardiovascular profile

Introduction. Patients with cardiovascular diseases have endothelial dysfunction and a higher risk of severe course of COVID-19, and thrombotic complications. Associated endotheliitis caused by virus penetration and cytokines storm leads to the release of tissue factor, the formation of excess thrombin and fibrin and thrombosis. The aim. To identify the potential of high-frequency ultrasound Dopplerography (HFUDG) for the assessment of microcirculatory disorders in post-COVID-19 patients with cardiovascular profile and to assess the microcirculatory bed condition before and after treatment with sulodexide. Materials and methods. 49 patients recovered from moderate-severe COVID-19 one month ago, aged 20–80, were examined. 24 patients, received prophylaxis with POACs for 1 month, formed group I, group II – 25 patients without prophylaxis. The nail bed of the upper limb 1st finger was examined using HFUDG and a 25 MHz sensor. Shape and spectrum of curves taken from dopplerograms were analyzed. The control examination was performed 4 weeks after therapy. Results. In patients after COVID19, depletion of spectral characteristics was revealed in comparison with dopplerograms of healthy individuals. The predominantly red part of the spectrum corresponding to the fastest particles was recorded. Slow-moving particles corresponding to the lighter part of the spectrum were nearly non-existent. In patients administrated POAC prophylaxis, amplitude indices were higher. Significant increase in D-dimer, antithrombin III, and soluble fibrin monomer complexes (SFMC) was also detected. The remaining parameters of the coagulogram were within the norm before and after treatment. After a course of sulodexide therapy, the spectral characteristics and coagulogram parameters returned to normal. Conclusion. HFUDG allows to detect stasis of capillary blood flow, the appearance of shunt blood flow corresponding to microtrombosis. Microcirculation indicators in post-COVID-19 patients improved after a course of preventive therapy with sulodexide.

Mechanical Deformation of Peripapillary Retina in Response to Acute Intraocular Pressure Elevation

Elevated intraocular pressure (IOP) may cause mechanical injuries to the optic nerve head (ONH) and the peripapillary tissues in glaucoma. Previous studies have reported the mechanical deformation of the ONH and the peripapillary sclera (PPS) at elevated IOP. The deformation of the peripapillary retina (PPR) has not been well-characterized. Here we applied high-frequency ultrasound elastography to map and quantify PPR deformation, and compared PPR, PPS and ONH deformation in the same eye. Whole globe inflation was performed in ten human donor eyes. High-frequency ultrasound scans of the posterior eye were acquired while IOP was raised from 5 to 30 mmHg. A correlation-based ultrasound speckle tracking algorithm was used to compute pressure-induced displacements within the scanned tissue cross-sections. Radial, tangential, and shear strains were calculated for the PPR, PPS, and ONH regions. In PPR, shear was significantly larger in magnitude than radial and tangential strains. Strain maps showed localized high shear and high tangential strains in PPR. In comparison to PPS and ONH, PPR had greater shear and a similar level of tangential strain. Surprisingly, PPR radial compression was minimal and significantly smaller than that in PPS. These results provide new insights into PPR deformation in response of IOP elevation, suggesting that shear rather than compression was likely the primary mode of IOP-induced mechanical insult in PPR. High shear, especially localized high shear, may contribute to the mechanical damage of this tissue in glaucoma.

Backscatter properties of two-layer phantoms using a high-frequency ultrasound annular array

In a previous study, an annular-array transducer was employed to characterize homogeneous scattering phantoms and excised rat livers using backscatter envelope statistics and frequency domain analysis. A sound field correction method was also applied to take into account the average attenuation of the entire scattering medium. Here, we further generalized the evaluation of backscatter coefficient (BSC) using the annular array in order to study skin tissues with a complicated structure. In layered phantoms composed of two types of media with different scattering characteristics, the BSC was evaluated by the usual attenuation correction method which revealed an expected large difference from the predicted BSC. In order to improve the BSC estimate, a correction method that applied the attenuation of each layer as a reference combined with a method that corrects based on the attenuation of the analysis position were applied. It was found that the method using the average attenuation of each layer is the most effective. This correction method is well adapted to the extended depth of field provided by an annular array.

A Wideband Noise and Harmonic Distortion Canceling Low-Noise Amplifier for High-Frequency Ultrasound Transducers

This paper presents a wideband low-noise amplifier (LNA) front-end with noise and distortion cancellation for high-frequency ultrasound transducers. The LNA employs a resistive shunt-feedback structure with a feedforward noise-canceling technique to accomplish both wideband impedance matching and low noise performance. A complementary CMOS topology was also developed to cancel out the second-order harmonic distortion and enhance the amplifier linearity. A high-frequency ultrasound (HFUS) and photoacoustic (PA) imaging front-end, including the proposed LNA and a variable gain amplifier (VGA), was designed and fabricated in a 180 nm CMOS process. At 80 MHz, the front-end achieves an input-referred noise density of 1.36 nV/sqrt (Hz), an input return loss (S11) of better than −16 dB, a voltage gain of 37 dB, and a total harmonic distortion (THD) of −55 dBc while dissipating a power of 37 mW, leading to a noise efficiency factor (NEF) of 2.66.

Recent Advances in Ultrasound Technology: Ultra-High Frequency Ultrasound for Reconstructive Supermicrosurgery

Background Currently, microsurgeons are in the era of supermicrosurgery and perforator flap reconstruction. As these reconstructions frequently utilize vessels that are smaller than a single millimeter, understanding of location of lymphatic vessels and perforator anatomy preoperatively is essential. To change with the times, the role of ultrasound has changed from just an adjunct to primary imaging of the choice in reconstructive supermicrosurgery. Recently, a novel ultrasonographic technique involving the use of ultra-high frequency ultrasound (UHFUS) frequencies has entered the scene, and appears a promising tool in surgical planning. Methods The literatures on the applications of UHFUS in reconstructive supermicrosurgery were retrieved and reviewed from more than 60 literatures have been published on the surgical applications of UHFUS. Results Nine studies were retrieved from the literature on the applications of UHFUS in reconstructive supermicrosurgery. The articles report both application for lymphatic surgery and perforator flaps. Conclusions UHFUS application involves an increasing number of reconstructive supermicrosurgery field. UHFUS is a valuable and powerful tool for any reconstructive surgeons who are interested in performing supermicrosurgery.