Ultrasound Frequency Research Articles

A semi‐empirical approach for determining the number density and void fraction of acoustic cavitation bubbles in sono‐reactors

AbstractA new semi‐empirical technic has been established relying on the linkage between the chemistry in the bulk liquid and that taking place in the acoustic cavitation bubble. The open‐source COPASI software has been used for the optimization of number density according to the total yield of a single bubble and the fitting of the experimental yield of hydrogen peroxide in the sonicated solution. It was observed that the number density is increased with the rise of ultrasound frequency from 200 to 1140 kHz, independently of the saturating gas nature (O2, Ar or air). Within this range of wave frequencies, i.e. from 200 to 1140 kHz, the number of active bubbles goes up from 9.35 × 107 to 3.65 × 1015 L−1 s−1. On the other side, it has been demonstrated that the number density obtained under air atmosphere is greater than that resulting either under argon or oxygen‐saturating gas. Interestingly, with respect to the saturating gas nature (O2, Ar, air) and the range of ultrasound frequency (200–1140 kHz), it was observed that the increase of number density was not necessarily accompanied by a proportional increase of void fraction (total volume of bubbles).

Electromagnetism - Properties of Erythrocytes

At the onset of blood flow, red blood cells (RBCs) align along the central plane of the vessels. In capillaries, RBCs transform from a biconcave disk into a parachute shape. As blood transitions from the arterial to the venous end, the hemoglobin in erythrocytes alters its magnetic susceptibility. Within approximately 0.6-0.8 seconds, oxygen is displaced from RBCs through diffusion. This study explores the fundamentals and interconnections of these processes.
 
 Blood samples from 35 different healthy individuals were analyzed. The research examined magnetic field induction in ferromagnetic toroids, formed by the alternative electric field with a square wave signal, and studied the AC in the secondary coil - a tube filled with blood. This study discusses the impact of RBC geometry and hemoglobin allosteric transitions on electric signal generation and its relevance to cellular metabolic activity in the body.
 
 The findings suggest that the AC field, originating from the heart's rotational dipole, can generate a magnetic field in RBCs, facilitating the allosteric transformations of hemoglobin. Hemoglobin's thermoelastic expansion and magnetostriction cause biconcave membrane oscillations at ultrasound frequencies. The resulting electroacoustic wave rotates charges at the cell's z-potential area, aids RBC migration into the flow plane, and enhances trans capillary diffusion of substances.
 
 An electroacoustic standing wave emerges between the oscillating RBCs, coinciding with the wavenumber of externally penetrating infrared light. The synergic influence on hemoglobin in capillaries causes the RBC membrane to create a temporally frequency-modulated wave, carrying resonance molecular frequencies. This wave regulates biochemical processes within and outside body cells.

Identifying Functional Lymph Nodes in Lower Extremity Lymphedema Patients: The Role of High-frequency Ultrasound.

Lymph nodes may play a potential role in lymphedema surgery. Radiologic evaluation of nodes may reveal the status of pathologic conditions but with limited accuracy. This study is the first to evaluate the efficacy of ultrasound in detecting functioning nodes in lymphedema patients and presents a criterion for determining the functionality of the lymph nodes. This retrospective study reviews 30 lower extremity lymphedema cases which were candidates for lymph node to vein anastomosis. Lymphoscintigraphy and magnetic resonant lymphangiography (MRL) imaging were compared with ultrasound features which were correlated to intraoperative indocyanine green (ICG) nodal uptake as an indication of functionality. Majority were International Society of Lymphology stage 2 late (50.0%) and stage 3 (26.7%). ICG positive uptake (functioning nodes) was noted in 22 (73.3%), while 8 patients (26.6%) had negative uptake (nonfunctioning). Ultrasound had significantly the highest specificity (100%) for identifying functional nodes followed by lymphoscintigraphy (55%) and MRL (36%; p = 0.002, p < 0.001, respectively). This was associated with 100% positive predictive value compared against lymphoscintigraphy (44%) and MRL (36%; p < 0.001 for both). The identified ultrasound imaging criteria for functioning lymph node were oval lymph node shape (Solbiati Index), morphology, vascularity pattern, and vascularity quantification. The use of ultrasound in nodal evaluation was proven effective in different pathologic conditions and demonstrated the best prediction for functionality of the lymph node based on the new evaluation criteria.

Influence of interactions between bubbles on physico-chemical effects of acoustic cavitation

Ultrasound technology has been extensively used as one of the efficient and economic methodology to achieve the desired outcomes in many applications by harnessing the physico-chemical effects of acoustic cavitation. However, the cavitation-associated effects, primarily determined by the oscillatory dynamics of cavitation bubbles, are considerably complex and still remain poorly understood. The main objective of this study was to perform a numerical analysis of the acoustic cavitation (i.e., the cavitation dynamics, the resultant temperature, pressure and chemical yields within collapsing bubbles), particularly focusing on the influence of the interactions between bubbles. A comprehensive model was developed to simulate the acoustic cavitation dynamics via combining the influences of mass transfer, heat conduction and chemical reactions as well as the interaction effects between bubbles. The results demonstrated that only the large bubble exerts a greater impact on the small one in a two-bubble system. Specifically, within parameter ranges covered this study, there are noticeable decreases in the expansion ratio of the small bubble, the resultant temperature, pressure and molar yields of free radicals, hence weakening the cavitation intensity and cavitation- associated physico-chemical effects. Moreover, the influences of the interactions between bubbles were further assessed quantitatively under various parameters, such as the ultrasound amplitude PA and frequency f, the distance between bubbles d0, the initial radius of the large bubble R20, as well as the liquid properties (e.g., surface tension σ and viscosity μ). It was found that the suppression effect can be amplified when subjected to ultrasound with an increased PA and/or a decreased f, probably due to a stronger cavitation intensity under this condition. Additionally, the suppression effect is also enhanced with a decrease in d0, σ and μ, but with R20 increasing. This study can contribute to deepening knowledge about acoustic cavitation and the resultant physical and/or chemical effects, potentially further facilitating the ultrasound-assisted various applications involving acoustic cavitation.

Controlling the Collective Behaviors of Ultrasound-Driven Nanomotors via Frequency Regulation.

Controlling the collective behavior of micro/nanomotors with ultrasound may enable new functionality in robotics, medicine, and other engineering disciplines. Currently, various collective behaviors of nanomotors, such as assembly, reconfiguration, and disassembly, have been explored by using acoustic fields with a fixed frequency, while regulating their collective behaviors by varying the ultrasound frequency still remains challenging. In this work, we designed an ultrasound manipulation methodology that allows nanomotors to exhibit different collective behaviors by regulating the applied ultrasound frequency. The experimental results and FEM simulations demonstrate that the secondary ultrasonic waves produced from the edge of the sample cell lead to the formation of complex acoustic pressure fields and microfluidic patterns, which causes these collective behaviors. This work has important implications for the design of artificial actuated nanomotors and optimize their performances.

A cancer cell nanotherapy method based on GHz film bulk acoustic resonator and nanoscale CaO2.

Sonodynamic therapy (SDT) is an emerging cancer treatment method in recent years. However, the ultrasound signal utilized for SDT is usually located at a low-frequency spectrum (<2MHz), and in the field of SDT research, few studies have focused on the exploration and development of ultrasound frequency. Studies have shown that the GHz-level ultrasound can increase cell membrane permeability and have a negligible effect on cell vitality. Herein, we reported the study of a GHz thin film bulk acoustic resonator as an ultrasound source for synergistic treatment with nanoscale calcium peroxide (CaO2). It was discovered that this ultrasound source ultimately achieved an efficient therapeutic outcome on mouse breast cancer cell line 4T1. Such GHz-level ultrasound application in SDT is of high significance to broaden the cognition and application scope of SDT.

Piezoelectric Effect Promoted Photoelectrochemical Water Splitting Ability of ZnIn2S4 Photoanode with Highly Exposed Active (110) Facets

AbstractIt is important to design high performance photoelectrode materials in the process of photoelectrochemical (PEC) water splitting. Herein, ZnIn2S4 nanomaterial with highly exposed active (110) facets were prepared by a simple hydrothermal method. Meanwhile, piezoelectric polarization was used to induce the generation of built‐in electric field, which can suppress the compounding of photogenerated charge carriers caused by structural defects at the semiconductor surface. By controlling the crystal facet structure, ZnIn2S4 with a highly exposed active (110) facet shows a better photoelectrochemical water splitting performance under ultrasound, and its photocurrent density increases with the increase of ultrasound frequency, reaching a maximum value of 0.36 mA/cm2 at 1.23 VRHE, which is 2.8 times higher than that without ultrasound. It can be concluded that the (110) facet of ZnIn2S4 can induce a larger internal piezoelectric potential which allows rapid electron transer at the ZnIn2S4 surface, under ultrasonic conditions. And the highly exposed (110) facet also provides more reactive sites, leading to further enhanced catalytic activity. Such nanomaterial with highly exposed active facets will provide inspiration for the construction of photoelectrode systems with high photoelectrochemical water splitting efficiency.

Reliability of assessing skeletal muscle architecture and tissue organization of the gastrocnemius medialis and vastus lateralis muscle using ultrasound and spatial frequency analysis.

The purpose of this study was to investigate inter- and intra-rater reliability as well as the inter-rater interpretation error of ultrasound measurements assessing skeletal muscle architecture and tissue organization of the gastrocnemius medialis (GM) and vastus lateralis (VL) muscle. The GM and VL of 13 healthy adults (22 ± 3 years) were examined thrice with sagittal B-mode ultrasound: intraday test-retest examination by one investigator (intra-rater) and separate examinations by two investigators (inter-rater). Additionally, images from one investigator were analysed by two interpretators (interpretation error). Muscle architecture was assessed by muscle thickness [MT], fascicle length [FL], as well as superior and inferior pennation angle [PA]. Muscle tissue organization was determined by spatial frequency analysis (SFA: peak spatial frequency radius, peak -6 dB width, PSFR/P6, normalized peak value of amplitude spectrum [Amax], power within peak [PWP], peak power percent). Reliability of ultrasound examination and image interpretation are presented as intraclass correlation coefficient (ICC), test-retest variability, standard error of measurement as well as bias and limits of agreement. GM and VL demonstrated excellent ICCs for inter- and intra-rater reliability, along with excellent ICCs for interpretation error of MT (0.91-0.99), showing minimal variability (<5%) and SEM% (<5%). Systematic bias for MT was less than 1 mm. For PA and FL poor to good ICCs for inter- and intra-rater reliability were revealed (0.41-0.90), with moderate variability (<12%), low SEM% (<10%) and systematic bias between 0.1-1.4°. Tissue organization analysis indicated moderate to good ICCs for inter- and intra-rater reliability. Notably, Amax and PWP consistently held the highest ICC values (0.77-0.87) across all analyses but with higher variability (<24%) and SEM% (<18%), compared to lower variability (<9%) and SEM% (<8%) in other tissue organization parameters. Interpretation error of all muscle tissue organization parameters showed excellent ICCs (0.96-0.999) with very low variability (≤1%) and SEM% (<2%), except Amax & PWP (TRV%: <6%; SEM%: <7%). Our findings demonstrated excellent inter- and intra-rater reliability for MT. However, agreement for PA, FL, and SFA parameters was not as strong. Additionally, MT and all SFA parameters exhibited excellent agreement for inter-rater interpretation error. Therefore, the SFA seems to offer the possibility of objectively and reliably evaluating ultrasound images.

Extraction of Vitamin B12 from Aqueous Solution by using Solid- Liquid Extraction and Ultra Sonic Frequency

A new method to uptake vitamin B12 in aqueous solution as pharmaceutical preparations by adsorption on the solid phase surface by using a multi-layer graphene oxide derivative compounds while the ultrasonic frequency wave was used to increase the efficiency of the extraction of drug from aqueous solution. Interlayer drug extraction conditions were optimized by studying a number of conditions that affect the extraction rate, including pH, ultrasound frequency, residence time of the solution inside the ultrasound device, the effect of the amount of graphene oxide derivative, and vitamin B12 concentration. The effect of temperature was also studied and a number of thermodynamic factors were generated. From the results, it was found that the best weight for the economically useful graphene oxide derivative is 0.01 grams at a concentration of 20 ppm relative to the concentration of the vitamin using an acidic medium of 2.1. The best temperature is 40 0C and within 50 Hz of the frequencies of the ultrasound device during the incubation period of 50 minutes. The proposed method was also applied to pharmaceutical samples containing vitamin B12, and the extraction rate was 95.35 %, with a very small error rate of 0.0465.

The effect of a rehabilitation program using ultrasound frequencies and thermal wax to increase the physical efficiency of handball players

The effect of a rehabilitation program using ultrasound frequencies and thermal wax to increase the physical efficiency of handball players

Multifrequency transcranial focusing based on acoustic lensing

Transcranial focused ultrasound (tFUS) possesses significant advantages such as non-invasiveness and high tissue penetration depth, making it a promising tool in the field of brain science. Acoustic holographic lenses enable the manipulation of sound fields through phase modulation, providing a low-cost and convenient approach to realize transcranial focusing. Acoustic holographic lenses have been successfully utilized for precise transcranial focusing in live mice to open the blood-brain barrier and for neural modulation, which shows considerable application potential. However, existing transcranial acoustic holographic lenses can only be driven by specific ultrasound frequencies and focus on predetermined locations, which restricts the flexibility in complex applications. To address this issue, this study establishes a multi-frequency transcranial focusing method based on acoustic holographic lenses to enhance its adaptability within the field of tFUS. By integrating acoustic holographic lenses designed for different focal positions at various frequencies, we generate multi-frequency acoustic holographic lenses suitable for transcranial focusing and conduct experiments to evaluate their performance. In simulations, for single-focus tasks, the PSNR of the proposed method achieves 32.16 dB and 40.18 dB under 1 MHz and 2 MHz ultrasound excitation; for multi-focus tasks, the PSNR values are 29.39 dB and 39.89 dB, respectively. In experiments, for single-focus tasks, the PSNR values of the proposed method are 27.48 dB and 32.33 dB under 1 MHz and 2 MHz ultrasound excitation; for multi-focus tasks, the PSNR values are 23.30 dB and 32.17 dB, respectively. These results demonstrate that the multi-frequency transcranial acoustic holographic lens can effectively modulate the sound field under varying ultrasound frequencies and create high-quality focal points at different locations behind the skull, which significantly enhances the application flexibility of transcranial acoustic holographic lenses.

The Effect of Transcranial Ultrasound Pulse Repetition Frequency on Sustained Inhibition in the Human Primary Motor Cortex: A Double-Blind, Sham-Controlled Study

The Effect of Transcranial Ultrasound Pulse Repetition Frequency on Sustained Inhibition in the Human Primary Motor Cortex: A Double-Blind, Sham-Controlled Study

PROTEUS: A Physically Realistic Contrast-Enhanced Ultrasound Simulator-Part I: Numerical Methods.

Ultrasound contrast agents have been used as vascular reporters for the past 40 years. The ability to enhance vascular features in ultrasound images with engineered lipid-shelled microbubbles has enabled break-throughs such as the detection of tissue perfusion or super-resolution imaging of the microvasculature. However, advances in the field of contrast-enhanced ultra-sound are hindered by experimental variables that are difficult to control in a laboratory setting, such as complex vascular geometries, the lack of ground truth, and tissue nonlinearities. In addition, the demand for large datasets to train deep learning-based computational ultrasound imaging methods calls for the development of a simulation tool that can reproduce the physics of ultrasound wave interactions with tissues and microbubbles. Here, we introduce a physically realistic contrast-enhanced ultrasound simulator (PROTEUS) consisting of four inter-connected modules that account for blood flow dynamics in segmented vascular geometries, intravascular microbubble trajectories, ultrasound wave propagation, and nonlinear microbubble scattering. The first part of this study describes numerical methods that enabled this development. We demonstrate that PROTEUS can generate contrast-enhanced radiofrequency data in various vascular architectures across the range of medical ultrasound frequencies. PROTEUS offers a customizable framework to explore novel ideas in the field of contrast-enhanced ultrasound imaging. It is released as an open-source tool for the scientific community.

Phonophoresis in Physiotherapy: Mechanisms, Applications, and Emerging Trends for Enhanced Drug Delivery and Therapeutic Efficacy

Phonophoresis, a widely utilized treatment in physiotherapy, combines topically applied gel or cream-based medications with ultrasonic therapy to enhance percutaneous absorption of pharmacological agents. The procedure employs ultrasound frequencies of 0.7 to 1.1 MHz with intensities ranging from 0.0 to 3.0 Watts per cm². Indications for phonophoresis span various inflammatory, deformative, dermatological, and rheumatic/neurological conditions. Recent studies suggest its clinical efficacy in pain relief and improved function, especially in conditions like lateral epicondylitis and osteoarthritis. The mechanism of action involves both thermal and non-thermal effects, with cavitation playing a key role in enhancing transdermal transport. Phonophoresis offers a non-invasive alternative for drug delivery, bypassing hepatic metabolism and minimizing systemic side effects. Various medicinal gels, particularly diclofenac, are used for transdermal drug delivery through phonophoresis. Low frequency phonophoresis has gained attention for enhancing transdermal transport, especially for macromolecules. Its applications extend beyond physiotherapy to include ocular drug delivery, nail therapy, gene therapy, and sports sciences. Clinical studies demonstrate the effectiveness of phonophoresis in conditions like anterior knee pain, tuberculous lymphadenitis, acute low back pain, and latent myofascial trigger points. Dosage considerations emphasize optimizing thermal effects without causing tissue damage. Studies highlight the potential of phonophoresis in relieving pain and improving function, particularly in knee osteoarthritis. Additionally, phonophoresis with Phyllanthus amarus nanoparticle gel shows promise in reducing pain and enhancing functional capacity in symptomatic knee osteoarthritis. In summary, phonophoresis stands as a valuable modality in physiotherapy, showcasing diverse applications and demonstrating clinical efficacy in various musculoskeletal and inflammatory conditions. Further research is warranted to explore its full potential and optimize treatment protocols.

Non-invasive Deep-Brain Imaging with 3D Integrated Photoacoustic Tomography and Ultrasound Localization Microscopy (3D-PAULM).

Photoacoustic computed tomography (PACT) is a proven technology for imaging hemodynamics in deep brain of small animal models. PACT is inherently compatible with ultrasound (US) imaging, providing complementary contrast mechanisms. While PACT can quantify the brain's oxygen saturation of hemoglobin (sO2), US imaging can probe the blood flow based on the Doppler effect. Further, by tracking gas-filled microbubbles, ultrasound localization microscopy (ULM) can map the blood flow velocity with sub-diffraction spatial resolution. In this work, we present a 3D deep-brain imaging system that seamlessly integrates PACT and ULM into a single device, 3D-PAULM. Using a low ultrasound frequency of 4 MHz, 3D-PAULM is capable of imaging the brain hemodynamic functions with intact scalp and skull in a totally non-invasive manner. Using 3D-PAULM, we studied the mouse brain functions with ischemic stroke. Multi-spectral PACT, US B-mode imaging, microbubble-enhanced power Doppler (PD), and ULM were performed on the same mouse brain with intrinsic image co-registration. From the multi-modality measurements, we further quantified blood perfusion, sO2, vessel density, and flow velocity of the mouse brain, showing stroke-induced ischemia, hypoxia, and reduced blood flow. We expect that 3D-PAULM can find broad applications in studying deep brain functions on small animal models.

Content of biologically active substances and antioxidant activity of aqueous-ethanol extracts of cultivated rosehip fruit obtained by ultrasonic extraction

The aim of the current work is to determine the main biologically active substances and antioxidant activity of aqueous-ethanolic extracts of cultivated rosehip fruit obtained by ultrasonic treatment. The extraction was performed under the following technological parameters: ultrasound frequency 37 kHz, solvents 50 and 70% ethanol, raw material: solvent ratio = 1:20, temperature 20, 40 and 60°C, duration 15, 30 and 60 min. Tannins, ascorbic acid and total phenolic contents were determined in the extracts. The highest tannin content (1.90%) was obtained by extraction with 50% ethanol, temperature 60°C and process duration 60 min. The total phenolic content under the different process conditions is comparable. Higher values of total phenols (45.43 mg GAE g-1) were determined at 50% ethanol solvent, 40°C temperature and 60 min process duration. The highest values of antioxidant activity, by the DPPH method, were reported in extracts with 50% ethanol, temperature 40°C and duration 60 min (422.5 μmol TE/g), and by FRAP method under the same extraction conditions - the value was almost twice lower (231.9 μmol TE).

A-352 - The use of High Frequency Ultrasound in Cutaneous Oncology Surgery

A-352 - The use of High Frequency Ultrasound in Cutaneous Oncology Surgery

Clinical Study and Progress of High Frequency Ultrasound in Peripheral Neuropathy

Clinical Study and Progress of High Frequency Ultrasound in Peripheral Neuropathy

Formation Model for Acoustic Characteristics of Solid Media with Ordered Fracturing

Introduction. The development of new structural materials and improvement of existing technologies for the production of new products on their basis lead to the emergence of new types of medium discontinuities. Therefore, the development of new models of discontinuities that take the previously ignored parameters into account seems to be relevant for the purposes of nondestructive testing and structural measurements. This concerns, e.g., the roughness of adjacent surfaces of microcrack ordered sets.Aim. Theoretical substantiation for the processes of elastic waves propagation through an elastic medium containing an ordered lattice of microcracks with boundary conditions in the linear slip approximation, modified by taking into account the parameters of micro-convexities of microcrack rough boundaries. Database formation for experimental studies aimed at determining the physical and mechanical characteristics of structural materials.Materials and methods. The acoustic characteristics of materials were determined based on the derivation and solutions of dispersion equations describing the formation and propagation of effective longitudinal, transverse, and Rayleigh surface elastic waves in elastic media with ordered cracking. Their values were also used to determine the effective speed of Rayleigh surface waves.Results. The conducted simulation of elastic wave formation processes showed that an increase in the concentration of microcracks leads to a decrease in the phase velocities of effective longitudinal, transverse, and surface waves, as well as to an increase in the attenuation coefficients at given ultrasound frequencies and material parameters.Conclusion. The radius of the microsphere that replaces the surface micro-convexity and the roughness parameter Rz have a significant impact on the formation of physical and mechanical characteristics of materials, which are determined by the results of ultrasonic measurements. The developed model can be recommended as a basis for interpreting the results of ultrasonic measurements.

Трещинообразование натуральной и модифицированной прессованием древесины березы повислой (Betula pendula Roth): эффект показателя внутреннего трения под влиянием внешних возмущений

Obtaining information about the presence of cracks in raw materials, blanks and wood products is neces-sary to make a decision on the purposes of its subsequent processing and operation. The method for diagnosing cracks in wood is based on measuring internal friction. For prepared samples of natural and modified wood, sawn from the stem part of drooping birch (Betula pendula Roth) trees growing in Khlevensky Forestry, Lipetsk region. (52.184130, 39.110463, ASL 157m), exposed to radial and tangential directions with ultrasound (frequency 24.5 kHz, exposure 0-20 minutes, step 5 minutes) and pulsed magnetic field (strength - 0.3 T, exposure 0-2 minutes, step 0.5 minutes). Next, the internal friction of the samples was studied on an experimental setup by measuring the logarithmic damping decrement based on free-bending vibrations. The absolute values of the dimensionless coefficient of internal friction Q-1, as the main structural parameter for samples of natural and modified wood, were obtained at a significance level of p=0.95: for humidity, in the presence of one crack, Q-1 decreased by 7.04% (D=0.08), in the presence of two cracks - by 8.4% (D=0.15), in the presence of three cracks - by 9.06% (D=0.15); for ultrasound in the presence of one crack Q-1 decreased by 7.17% (D=0.05), in the presence of two cracks - by 8.46% (D=0.05), in the presence of three cracks - by 9.12% (D=0.09); for a pulsed magnetic field in the presence of one crack Q-1 decreased by 7.14% (D=0.05), in the presence of two cracks - by 8.39% (D=0.09), in the presence of three cracks - by 9.02% (D=0.09). When testing the samples of natural wood and pressure-modified drooping birch (Betula pendula Roth) wood, we obtained an asymptotic equation was obtained for ap-proximating the dependence of the decrease in Q-1 on the number of cracks, with the approximation value R2=0.994. The study of the dependence of internal friction on the process of crack formation in various types of wood provides preparation for the next stage - the construction of a prototype system for non-destructive testing of defects.