I am currently a member of Dahl's Ultrasound lab. My research interests are focused on medical ultrasound imaging, particularly on intravascular transducer design and using microbubbles as ultrasound contrast agents.
Improving the Function and Engraftment of Transplanted Pancreatic Islets Using Pulsed Focused Ultrasound Therapy.
2019; 9 (1): 13416
This study demonstrates that pulsed focused ultrasound (pFUS) therapy can non-invasively enhance the function and engraftment of pancreatic islets following transplantation. In vitro, we show that islets treated with pFUS at low (peak negative pressure (PNP): 106kPa, spatial peak temporal peak intensity (Isptp): 0.71W/cm2), medium (PNP: 150kPa, Isptp: 1.43W/cm2) or high (PNP: 212kPa, Isptp: 2.86W/cm2) acoustic intensities were stimulated resulting in an increase in their function (i.e. insulin secretion at low-intensity: 1.15±0.17, medium-intensity: 2.02±0.25, and high-intensity: 2.54±0.38 fold increase when compared to control untreated islets; P<0.05). Furthermore, we have shown that this improvement in islet function is a result of pFUS increasing the intracellular concentration of calcium (Ca2+) within islets which was also linked to pFUS increasing the resting membrane potential (Vm) of islets. Following syngeneic renal sub-capsule islet transplantation in C57/B6 mice, pFUS (PNP: 2.9MPa, Isptp: 895W/cm2) improved the function of transplanted islets with diabetic animals rapidly re-establishing glycemic control. In addition, pFUS was able to enhance the engraftment by facilitating islet revascularization and reducing inflammation. Given a significant number of islets are lost immediately following transplantation, pFUS has the potential to be used in humans as a novel non-invasive therapy to facilitate islet function and engraftment, thereby improving the outcome of diabetic patients undergoing islet transplantation.
View details for DOI 10.1038/s41598-019-49933-0
View details for PubMedID 31527773
Ultrasound/microbubble-mediated targeted delivery of anticancer microRNA-loaded nanoparticles to deep tissues in pigs.
Journal of controlled release : official journal of the Controlled Release Society
In this study, we designed and validated a platform for ultrasound and microbubble-mediated delivery of FDA-approved pegylated poly lactic-co-glycolic acid (PLGA) nanoparticles loaded with anticancer microRNAs (miRNAs) to deep tissues in a pig model. Small RNAs have been shown to reprogram tumor cells and sensitize them to clinically used chemotherapy. To overcome their short intravascular circulation half-life and achieve controlled and sustained release into tumor cells, anticancer miRNAs need to be encapsulated into nanocarriers. Focused ultrasound combined with gas-filled microbubbles provides a noninvasive way to improve the permeability of tumor vasculature and increase the delivery efficiency of drug-loaded particles. A single handheld, curvilinear ultrasound array was used in this study for image-guided therapy with clinical-grade SonoVue contrast agent. First, we validated the platform on phantoms to optimize the microbubble cavitation dose based on acoustic parameters, including peak negative pressure, pulse length, and pulse repetition frequency. We then tested the system in vivo by delivering PLGA nanoparticles co-loaded with antisense-miRNA-21 and antisense-miRNA-10b to pig liver and kidney. Enhanced miRNA delivery was observed (1.9- to 3.7-fold increase) as a result of the ultrasound treatment compared to untreated control regions. Additionally, we used highly fluorescent semiconducting polymer nanoparticles to visually assess nanoparticle extravasation. Fluorescent microscopy suggested the presence of nanoparticles in the extravascular compartment. Hematoxylin and eosin staining of treated tissues did not reveal tissue damage. The results presented in this manuscript suggest that the proposed platform may be used to safely and noninvasively enhance the delivery of miRNA-loaded nanoparticles to target regions in deep organs in large animal models.
View details for DOI 10.1016/j.jconrel.2019.07.024
View details for PubMedID 31326463
Cylindrical Transducer for Intravascular ARFI Imaging: Design & Feasibility.
IEEE transactions on ultrasonics, ferroelectrics, and frequency control
Intravascular acoustic radiation force impulse (IV-ARFI) imaging has the potential to identify vulnerable atherosclerotic plaques and improve clinical treatment decisions and outcomes for patients with coronary heart disease. Our long-term goal is to develop a thin, flexible catheter probe that does not require mechanical rotation to achieve high-resolution, real-time IV-ARFI imaging. In this work, we propose a novel cylindrical transducer array design for IV-ARFI imaging and investigate the feasibility of this approach. We present the construction of a 2.2-mm long, 4.6-Fr cylindrical prototype transducer to demonstrate generating large ARFI displacements from a small toroidal beam, and we also present simulations of the proposed IV-ARFI cylindrical array design using Field II and a cylindrical finite-element model of vascular tissues and soft plaques. The prototype transducer was found to generate peak radial displacements of over 10 μm in soft gelatin phantoms, and simulations demonstrate the ability of the array design to obtain ARFI images and distinguish soft plaque targets from surrounding, stiffer vessel wall tissue. These results suggest that high-resolution, real-time IV-ARFI imaging is possible using a cylindrical transducer array.
View details for DOI 10.1109/TUFFC.2019.2942347
View details for PubMedID 31545716
- Axially-segmented cylindrical array for intravascular shear wave imaging SPIE-INT SOC OPTICAL ENGINEERING. 2019
Effect of Pulsed Focused Ultrasound on the Native Pancreas.
Ultrasound in medicine & biology
Pulsed focused ultrasound (pFUS) utilizes short cycles of sound waves to mechanically shake cells within tissues which, in turn, causes transient local increases in cytokines, growth factors and cell adhesion molecules. Although the effect of pFUS has been investigated in several different organs including the kidney, muscle and heart, its effect on the pancreas has not been investigated. In the present work, we applied pFUS to the rodent pancreas with the following parameters: 1.1-MHz frequency, 5-Hz pulse repetition frequency, 5% duty cycle, 10-ms pulse length, 160-s duration. Low-intensity pFUS had a spatial average temporal average intensity of 11.5 W/cm2 and a negative peak pressure of 3 MPa; high-intensity pFUS had a spatial average temporal average intensity of 18.5 W/cm2 and negative peak pressure of 4 MPa. Here we found that pFUS changed the expression of several cytokines while having no effect on the underlying tissue histology or health of pancreatic cells (as reflected by no significant change in plasma levels of amylase and lipase). Furthermore, we found that this effect on cytokine expression in the pancreas was acoustic intensity dependent; while pFUS at low intensities turned off the expression of several cytokines, at high intensities it had the opposite effect and turned on the expression of these cytokines. The ability to non-invasively manipulate the microenvironment of the pancreas using sound waves could have profound implications for priming and modulating this organ for the application of cellular therapies in the context of both regenerative medicine (i.e., diabetes and pancreatitis) and oncology (i.e., pancreatic cancer).
View details for DOI 10.1016/j.ultrasmedbio.2019.11.016
View details for PubMedID 31882169
Diamond’s third-order elastic constants: ab initio calculations and experimental investigation
Journal of Materials Science
2017; 52 (6): 3447–3456
View details for DOI 10.1007/s10853-016-0633-x
- Piezoelectric-Layered Structures Based on Synthetic Diamond Piezoelectric Materials InTech. 2016: 161–199
Lamb waves dispersion curves for diamond based piezoelectric layered structure
Applied Physics Letters
2016; 108: 5
View details for DOI 10.1063/1.4943945
Extended temperature dependence of elastic constants in cubic crystals
2015; 61: 1-5
To extend the theory of the temperature dependence of the elastic constants in cubic crystals beyond the second- and third-order elastic constants, the fourth-order elastic constants, as well as the non-linearity in the thermal expansion temperature dependence, have been taken into account. Theoretical results were represented as temperature functions of the effective elastic constants and compared with experimental data for a number of cubic crystals, such as alkali metal halides, and elements gold and silver. The relations obtained give a more accurate description of the experimental temperature dependences of second-order elastic constants for a number of cubic crystals, including deviations from linear behavior. A good agreement between theoretical estimates and experimental data has been observed.
View details for DOI 10.1016/j.ultras.2015.02.020
View details for Web of Science ID 000354545200001
View details for PubMedID 25819879
- Study of high-overtone bulk acoustic resonators based on the Me1/AlN/Me2/(100) diamond piezoelectric layered structure ACOUSTICAL PHYSICS 2015; 61 (4): 422-433
Resonant transformation of acoustic waves observed for the diamond based HBAR
2015 Joint Conference of the IEEE International Frequency Control Symposium & the European Frequency and Time Forum
View details for DOI 10.1109/FCS.2015.7138866
- Third-order elastic constants: ab initio study and experimental results (in Russian) The 58 International MIPT conference 2015
UHF acoustic attenuation and quality parameter limits in the diamond based HBAR
2015 Joint Conference of the IEEE International Frequency Control Symposium & the European Frequency and Time Forum
View details for DOI 10.1109/FCS.2015.7138799
Study of microwave acoustic attenuation in a multifrequency bulk acoustic wave resonator based on a synthetic diamond single crystal
2015; 61 (6): 12
View details for DOI 10.1134/S1063771015050164
- Lamb waves in piezoelectric layered structure “Al/AlN/Mo/diamond” (in Russian) The 58 International MIPT conference 2015
- Second-order and third-order elastic constants of B4C ceramics PHYSICS OF THE SOLID STATE 2014; 56 (8): 1574-1578
- Technology of manufacturing piezoelectric AlN film transducer on substrate of synthetic diamond single crystal (in Russian) Izvestiya Vysshikh Uchebnykh Zavedenii. Seriya Khimiya i Khimicheskaya Tekhnologiya 2014; 57 (5): 17-21
- The IIa synthetic diamond as a substrate for high quality microwave high overtone bulk acoustic resonator International Conference on Diamond and Carbon Materials 2014
- AlN/single crystalline diamond piezoelectric structure as a high overtone bulk acoustic resonator APPLIED PHYSICS LETTERS 2013; 102 (11)
- Microwave Acoustic Properties of Diamond Single Crystal as a Substrate for High-overtone Bulk Acoustic Resonator 2013 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) 2013: 1680-1683
- Elastic Properties of Synthetic Diamond Single Crystal (in Russian) Izvestiya Vysshikh Uchebnykh Zavedenii. Seriya Khimiya i Khimicheskaya Tekhnologiya 2013; 56 (7): 50-52
- Investigation of Piezoelecrtic Microwave Acoustic Properties of the Layered Structure AlN/Diamond Single Crystal (in Russian) International Symposium Physics of Crystals 2013
- Method development for acoustoelectronic devices sensor technology creation based on synthetic diamond single crystals (in Russian) Science and Technology Symposium and Forum «Research and Development on Priority Directions of Scientific-Technological Complex in Russia on 2007 – 2013 years» 2013
- Investigation of nonlinear Electromechanical Properties of Lithium Tantalate Single Crystal (in Russian) International Symposium Physics of Crystals 2013
- Experimental investigation of the linear and nonlinear elastic properties of synthetic diamond single crystal (in Russian) Journal of Siberian Federal University. Mathematics & Physics 2013; 6 (1): 120-126
- The study of physicochemical and acoustic properties of piezoelectric layered structure Me1/AlN/Me2/(100) diamond (in Russian) School-Seminar of Young Scientists of the Central Region "The participation of young scientists in fundamental and applied research to develop new carbon and nanocarbon materials" 2013: 76–79
- Experimental Investigation of BAW Propagation in Lithium Tantalate Oxide under the Influence of Uniaxial Pressure and DC Electric Field 2013 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) 2013: 1634-1637
Temperature Coefficients of Elastic Constants of Trigonal, Hexagonal, and Tetragonal Crystals
IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
2012; 59 (2): 311-314
Temperature coefficients of elastic constants (TC(IJ)) for trigonal, hexagonal, and tetragonal crystals have been obtained. The TC(IJ) of several trigonal, hexagonal, and tetragonal crystals have been calculated and compared with known experimental data. The nature of the anomalous TC66 of quartz has been discussed in detail.
View details for DOI 10.1109/TUFFC.2012.2192
View details for Web of Science ID 000300847100016
View details for PubMedID 24626040
- Elastic waves in piezoelectric layered structures (in Russian) Journal of Siberian Federal University. Mathematics & Physics 2012; 5 (2): 164-168
- Investigation of elastic waves propagation in synthetic diamond single crystal (in Russian) 8th International Conference Carbon: Fundamental Problems of Science, Materials, Technology 2012
- Elastic properties of synthetic diamond single crystal (in Russian) RAS Acoustic Session and XXV Session of Russian Acoustic Society 2012
- Experimental Investigation of BA W Propagation in Lithium Tantalate Oxide Single Crystals Under the Influence of Uniaxial Pressure 2012 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) 2012: 491-494
- Influence of the Temperature and Uniaxial Pressure on the Elastic Properties of Synthetic Diamond Single Crystal 2012 IEEE INTERNATIONAL ULTRASONICS SYMPOSIUM (IUS) 2012: 763-766
Temperature Coefficients of Elastic Constants of Trigonal and Tetragonal Crystals
2011 JOINT CONFERENCE OF THE IEEE INTERNATIONAL FREQUENCY CONTROL SYMPOSIUM/EUROPEAN FREQUENCY AND TIME FORUM PROCEEDINGS
View details for Web of Science ID 000295261600106
- Determination of the third-order elastic constants of a diamond single crystal on the by the investigation small amplitude acoustic waves propagation under final mechanical stress (in Russian) The 54 International MIPT conference 2011: 84–85