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Objective: As a novel noninvasive modality of oncotherapy or stroke treatment, high-intensity focused ultrasound (HIFU) has drawn more and more attention in the past decades. Whereas, real-time temperature monitoring and treatment-efficacy evaluation are still the key issues for HIFU therapy. Methods: Based on the temperature–conductivity relation of tissues with a sharp conductivity variation of irreversible thermocoagulation at 69 °C, a noninvasive method of treatment-efficacy evaluation for HIFU ablation using the magneto-acousto-electrical tomography (MAET) technology is theoretically studied. By applying the nonlinear Khokhlov–Zabolotskaya–Kuznetsov equation and Pennes equation, a cylindrical model is established to simulate the distributions of pressure, temperature, and conductivity with the consideration of harmonic components. Results: The MAET signals are simulated to analyze the characteristics of the peak amplitude and the axial interval of the two clusters generated by the conductivity boundary of HIFU ablation. Conclusion: The axial interval can be used as the indictor to evaluate the size of HIFU ablation with the minimum axial width of one wavelength. Significance: The favorable results demonstrate the feasibility of real-time treatment-efficacy evaluation for HIFU therapy using the MAET technology and suggest potential applications in clinical practice.

Two novel benzoxazine-containing porous polymers, BPOP-1 and BPOP-2, have been synthesized by the direct Sonogashira-Hagihara coupling reactions of two brominated benzoxazine derivatives with a tetrahedral silicon-centered monomer. These polymers exhibit high porosity with the highest Brunauer-Emmer-Teller (BET) surface area of 623 m2 g−1 and the highest total pore volume of up to 1.78 cm3 g−1. Porosity comparison with other benzoxazine-containing porous polymers shows that the introduction of tetrahedral silicon-centered units into the porous networks is an efficient strategy to improve the porosity of the final porous polymers. For applications, these polymers possess good carbon dioxide uptakes of up to 1.79 mmol g−1 (7.9 wt%) at 273 K and 1.0 bar, a comparably high binding ability with CO2 with an adsorption enthalpy of up to 29.6 kJ mol−1, as well as a moderate hydrogen uptake of up to 5.87 mmol g−1 (1.12 wt%) at 77 K and 1.0 bar. These values are comparable to or higher than other porous polymers with a level of surface areas and previously reported benzoxazine-containing porous polymers, thereby suggesting their potential applications as efficient solid absorbents for storing CO2 and H2.

Diabetic nephropathy (DN) is one of the severe complications of diabetes. Nowadays, effective treatment for end-stage renal disease (ESRD) patients is still limited. HK-2 cells were stimulated with serum from phosphate-buffered saline (PBS) or Jiawei Shuilu Erxiandan (JSE)-treated DN mice, then long non-coding RNA (lncRNA) CLYBL-AS2 was discovered by RNA sequence, following the comparison of the serum from normal patients with DN patients to confirm the role of lncCLYBL-AS2. Next, we performed in vitro studies to explore the effect of lncCLYBL-AS2 in DN and its molecular mechanism. Coptis, as one of the components of JSE, could decrease the expression of lncCLYBL-AS2, which is increased in DN and correlated with the severity of DN. Knockdown/overexpression of lncCLYBL-AS2 inhibited/promoted the invasion and fibrogenesis of HK-2 cells. Furthermore, lncCLYBL-AS2 was negatively correlated with miR-204-4p with a positive correlation with SNAI1; eventually, CLYBL-AS2 regulated SNAI1 by binding to miR-204-5p, which accounted for the inhibition of epithelial–mesenchymal transition (EMT) and fibrogenesis. LncCLYBL-AS2 inhibited by Coptis improved EMT and fibrogenesis in HK-2 cells through miR-204-5p-SNAI1 axis, therefore, lncCLYBL-AS2 could serve as a potential diagnosis and therapeutic target for DN.

Polysaccharides were extracted from Pachyrrhizus erosus (PEP) and three fractions (PEP60, PEP80 and PEP95) were separated by ethanol precipitation. Antidiabetic activities of three fractions were evaluated by streptozotocin-induced diabetic mouse model. Three PEP fractions reduced fasting blood glucose levels in mice, and regulated the levels of glycated serum protein, total triglyceride and total cholesterol in serum. In liver, the levels of glycogen content, glutathione peroxidase and superoxide dismutase activities and lipid peroxidation were recovered by PEP fractions. The histological analysis indicated that PEP fractions could protect the tissue structures of pancreas, liver and kidney from diabetic damages. In kidney, PEP fractions decreased the mesangial matrix index and inhibited the expression of transforming growth factor-β1. PEP95 showed stronger antidiabetic activity than PEP60 and PEP80. PEP95-DS was separated from PEP95 by DEAE-cellulose and Sephadex G-100 column chromatography. The chemical characteristics of PEP95-DS were evaluated. The average molecular weight of PEP95-DS was 11.4kDa, and it was composed of mannose: rhamnose: glucosamine: glucose: galactose: xylose: arabinose was 5.4:1.7:8.5:160.7:11.8:1:2.7. Furthermore, the spectral characteristics of PEP95-DS were analyzed. Our results indicated PEP could be used as a function ingredient in foods to prevent oxidation and diabetes.

Exploring the mechanism of the interaction between milrinone drug and lysozyme is important for us to understand the transportation in vivo, metabolism and kinetics of drug. The fluorescence spectra results showed that drug affected the surrounding microenvironment of lysozyme, and took place a dynamic quenching process in lysozyme complex solution. The experimental results of the differential scanning calorimetry and thermal gravimetric analysis demonstrated that (1) lysozyme and milrinone interacted with each other in water, (2) the conformation of lysozyme could be changed due to the existing milrinone drug, and (3) the stability and calorimetric enthalpy of the lysozyme complex solution could be decreased with an increased drug concentration.

Two novel ferrocene-containing porous organic polymers, FPOP-1 and FPOP-2, have been prepared by Sonogashira-Hagihara coupling reactions of 1,1′-diethynylferrocene with tri(4-bromophenyl)phenylsilane or tetrakis(4-bromophenyl)silane. The resultant polymers show high thermal stability and high porosity with Brunauer-Emmer-Teller (BET) surface area of up to 954 m2 g−1 (FPOP-2) and total pore volume of up to 0.74 cm3 g−1 (FPOP-2). The porosity comparison with other ferrocene-containing porous polymers indicates that the introduction of tetrahedral silicon-centered units is beneficial to enhancing the porosity. The gas sorption investigations reveal that these polymers possess comparable CO2 capacities of 1.44 mmol g−1 (6.3%) at 273 K and 1.0 bar, and 0.91 mmol g−1 (4.0 wt%) at 298 K and 1.0 bar (FPOP-2), and comparable H2 uptakes of 7 mmol g−1 (1.4 wt%) (FPOP-2). The values are higher than other non-ferrocene-containing porous polymers with higher porosity, thereby indicating that the incorporation of ferrocene units can improve the gas sorption property. Furthermore, these results demonstrate that these materials can be promisingly utilized as solid absorbents for storing CO2 and H2.

Silicon-containing porous organic polymers, POP-1∼POP-4, have been prepared by Sonogashira-Hagihara coupling reactions of tetrahedral silicon-centered monomers, i.e. , tetrakis(4-bromophenyl)silane ( p -Si) and tetrakis(3-bromophenyl)silane ( m -Si), and pyridine-based precursors, i.e. , 2,5-diethynylpyridine ( p -DP) and 2,6-diethynylpyridine ( m -DP). Compared with other porous polymers, the resulting materials exhibit high thermal stability and tunable porosity from nearly no porosity to moderate porosity with Brunauer-Emmett-Teller (BET) surface area of up to 410 m 2 g −1 and pore volume of up to 0.34 cm 3 g −1 . It is found that their porosities largely depend on the structure geometry of silicon-centered and pyridine-based monomers, as well as the reactivity of pyridine-based monomers. Further comparison with other silicon-containing porous polymers reveals that co-polymerization, i.e. , introducing the second monomer is an efficient way to tune the porosity of the final materials. For applications, POP-1 and POP-2 possess moderate carbon dioxide uptakes of up to 1.41 mmol g −1 at 273 K and 1.03 bar, and 0.87 mmol g −1 (3.83 wt%) at 298 K and 1.01 bar (POP-1), as well as a comparably high binding ability with CO 2 with an adsorption enthalpy of 29.3 kJ mol −1 , suggesting their potential applications as promising candidates for capturing and storing CO 2 .

With the development of thermal therapy, new technology of temperature monitoring has attracted widespread attention. Based on the relation between impedance and temperature, treatment time dependences of the pressure peak and the derivative, magnetoacoustic tomograpby with magnetic induction (MAT-MI) is applied to monitor temperature changes. A distinct peak in the curve of the peak amplitude derivative was observed, which can be contributed to the sharp conductivity variation of thermal ablation at the temperature reaches 69°C, demonstrating a promising application for non-invasive real-time temperature monitoring technology using MAT-MI.

Silk fibroin (SF) is a protein polymer derived from insects, which has unique mechanical properties and tunable biodegradation rate due to its variable structures. Here, the variability of structural, thermal, and mechanical properties of two domesticated silk films (Chinese and Thailand B. Mori) regenerated from formic acid solution, as well as their original fibers, were compared and investigated using dynamic mechanical analysis (DMA) and Fourier transform infrared spectrometry (FTIR). Four relaxation events appeared clearly during the temperature region of 25 &deg, C to 280 &deg, C in DMA curves, and their disorder degree (fdis) and glass transition temperature (Tg) were predicted using Group Interaction Modeling (GIM). Compared with Thai (Thailand) regenerated silks, Chin (Chinese) silks possess a lower Tg, higher fdis, and better elasticity and mechanical strength. As the calcium chloride content in the initial processing solvent increases (1%&ndash, 6%), the Tg of the final SF samples gradually decrease, while their fdis increase. Besides, SF with more non-crystalline structures shows high plasticity. Two &alpha, relaxations in the glass transition region of tan &delta, curve were identified due to the structural transition of silk protein. These findings provide a new perspective for the design of advanced protein biomaterials with different secondary structures, and facilitate a comprehensive understanding of the structure-property relationship of various biopolymers in the future.

The emergence of shared electric scooters (E-Scooters) has drawn the significant attention of local governments in many urban areas. Despite the fast growth in the number of trips, current guidelines for using E-Scooters have consistently experienced lags in development. Existing guidelines, in some cities, are rather vague and vary drastically across different areas. This paper aims to analyze current municipal requirements for the use of E-Scooters in the U.S., and to discuss more gaps for improvement. Specifically, E-Scooter user guidelines of 156 cities were explored. A multifaceted analysis was conducted to characterize the distinct features of E-Scooter user guidelines. A total of sixteen key attributes were identified and two categorizing procedures were implemented in the analysis. The comparative results show the completeness of information and similarities between cities. We conclude that municipalities should introduce more actionable guidelines driven by quantitative performance metrics.

Strong artificial magnetic responses play a pivotal role in the unique optical properties of metamaterials, such as cloaking, Fano resonance, and negative refraction. We investigate the magnetic resonances of gain-assisted Si nanospheres and SiO2–Si nanoshells. It is found that the super-resonances occur successively at the octupole, quadrupole, and dipole magnetic modes of the active Si nanosphere or SiO2–Si nanoshell by changing the gain coefficient. At the super-resonances, the magnetic scatterings and the local electric fields are all extremely enhanced. The corresponding surface-enhanced Raman spectroscopy (SERS) enhancement factors at the magnetic super-resonances could reach about 1010–1015, which are enough for single-molecule detection. In particular, the electric scatterings of the active Si nanosphere and SiO2–Si nanoshell are all very weak at the super-resonances. Therefore, the active Si nanosphere and SiO2–Si nanoshell should be excellent SERS substrates with weak background radiation. The e...

Nanoscale particles (NP) were observed in a Ni60–Ag–Si 3 N 4 –Y 2 O 3 laser alloying (LA) layer on a TA7 titanium alloy, NP usually locate on the grain boundaries, which are able to block the motion of dislocation in a certain extent. Such layer mainly consisted of γ-Ni, TiN, γ-(Fe, Ni), TiAg and lots of amorphous phases. The wear resistance of such layer with laser scanning speed 3 mm/s was better than that of a LA layer with 6 mm/s, which was mainly ascribed to an uniform microstructure and less defect of layer. The high laser scanning speed made the existing time of laser molten pool be shorter than before, favoring the formation of a fine microstructure. However, the defects, such as pores were produced in LA layer (higher scanning speed), decreasing the wear resistance.

For enhanced energy utilization with improved flexibility and capability for object manipulation, a focused acoustic vortex (FAV) is devised by installing a spherical acoustic lens on a circular array of planar sector transducers. Based on the acoustic refraction of a concave spherical acoustic lens, numerical simulations show that an FAV with considerable pressure gain and strengthened acoustic gradient force (AGF) can be produced by the effective concentration of acoustic waves. The performance of rotational object trapping is shown by the axial and radial distributions of the AGF for FAVs of different orders. Elastic objects of nanometer, micrometer, millimeter, and even larger-than-wavelength size can be captured with the trapping radius determined by the topological charge. With the established 16-channel experimental system, FAVs of different orders are verified by their clear pressure circles and phase spirals. The trapping radius and rotation speed of object capture are demonstrated using polyethylene particles of various sizes and FAVs of different orders. The favorable results provide an experimentally applicable method of FAV generation using the simplified circular transducer array to accomplish more accurate, stable, and flexible object manipulations with strengthened AGFs. Also, FAVs could offer an efficient means of high-intensity focused ultrasound therapy to improve the therapeutic effect of tumor treatments by accumulating drug particles, thereby enabling more potential applications in clinical practice.

As the main way of underwater data transmission, acoustic communication is still limited by the low-level signal-to-noise ratio and channel capacity. The orbital angular momentum (OAM) based acoustic communication of acoustic vortex (AV) provides a new dimension to data transmission with an expanded channel capacity. Theoretical analyses and experimental measurements for the OAM communication of AV beams based on single-ring transceiver arrays are studied in air. Coaxial multi-OAM AV beams are generated with multiple topological charges encoded by the binary ASCII codes of various letters. The OAM modes of the AV beams are decoded with limited acoustic pressures detected by the single-ring receiver array around the vortex center based on the orthogonal property. It is proven that the channel capacity of the communication system can be increased effectively by the OAM modes of AVs, which are beneficial to data encryption and transmission without mutual interference of AVs of different orders. The favorable results provide theoretical bases and technical support to data transmission and OAM decoding for the OAM communication of AV beams using simplified single-ring transceiver arrays.

Objective: As the multi-physics imaging approach, magnetoacoustic tomography with magnetic induction (MAT-MI) attracts more and more attentions, focusing on image reconstruction for conductivity isotropic tissues. Methods: By introducing vector analyses to electromagnetic stimulation and magnetoacoustic excitation for a single-layer cylindrical conductivity anisotropic model, the acoustic source strength (ASS) of MAT-MI is derived in explicit formula and the influence of the anisotropic conductivity tensor is also analyzed. Results: Theoretical and numerical studies demonstrate that the ASS generated at the tissue boundary is composed of an alternating current (AC) fluctuation and a direct current (DC) bias, where the distribution of the AC fluctuation with respect to the spatial angle exhibits a double-period cosine function, and the DC bias remains constant at each angle. The dependences of the AC fluctuation and the DC bias on the anisotropic component ratio (ACR) and the conductivity tensor are proved by numerical results, which are also verified by the special cases of the zero AC fluctuation for the conductivity isotropic medium and the negative DC bias of the low-conductivity medium. Conclusion: With the measurements of the ASS around the model, the anisotropic conductivity tensor can be reconstructed by the amplitudes of the AC fluctuation and the DC bias with the conductivity of the isotropic surrounding medium. Significance: The favorable results provide a new method for anisotropic conductivity measurement, and suggest the application potential of MAT-MI in biomedical imaging and nondestructive testing for conductivity anisotropic tissues.

A fiber-optic micro-electromechanical systems (MEMS) extrinsic Fabry-Perot interferometer (EFPI) pressure sensor exploiting microwave photonics filtering technique is firstly proposed and experimentally demonstrated. A single-bandpass microwave photonic filter (MPF) which mainly consists of a spectrum-sliced light source, a pressurized EFPI, a phase modulator (PM) and a length of dispersion compensating fiber (DCF) is demonstrated. The frequency response of the filter with respect to the pressure is studied. By detecting the resonance frequency shifts of the MPF, the pressure can be determined. The theoretical and experimental results show that the proposed EFPI pressure sensor has a higher resolution and higher speed than traditional methods based on optical spectrum analysis. The sensitivity of the sensor is measured to be as high as 86 MHz/MPa in the range of 0–4MPa.

The acoustic power (AP) of high-intensity focused ultrasound (HIFU) shows great potential for ensuring the efficacy and safety of tumor treatment. By considering the energy of the harmonics, an easily applicable nonlinear AP measurement method for HIFU based on the fundamental focal axial vibration velocity (F-FAVV) is proposed. The focal pressures of the harmonics with respect to the surface vibration velocity are simulated, and a piecewise function of the required harmonic order is developed based on the 40-dB attenuation criterion of the harmonic-to-fundamental ratio. With the relationships between the power gain and the FAVVs of the harmonics, the dependence of AP on the F-FAVV is achieved by summing the harmonic powers. The APs of HIFU under various surface vibration velocities are verified by experimental measurements of the F-FAVV using a laser vibrometer and the corresponding integration results over the transducer surface. Good agreement between the numerical and experimental results demonstrates the feasibility of accurate AP measurement for HIFU using the F-FAVV and suggests the potential for applications in biomedical engineering.

A novel approach for contrast enhancement of the edge is proposed by employing Airy spiral filter in optical microscopy. The proposed technique reduces the diffraction noise more efficiently and achieves high quality edge enhancement images.

In treating a circular point-source array using the phase-coded method, a composite acoustic field of multiple off-axis acoustic vortices (AVs) with a centered quasi-plane wave is proposed which is superimposed by an AV beam and a co-axial non-AV beam generated by the even- and odd-numbered source arrays, respectively. The acoustic pressure and the phase of the composite acoustic field are derived using explicit formulae and demonstrated by numerical simulations. Off-axis sub-AVs (SAVs) are shown to be formed at the intersections of the radial pressure distributions of the AV and non-AV beams for the same pressure amplitude and opposite phases. Off-axis SAVs can be generated on a circumference centered with a regular polygon of quasi-plane waves. The radii and azimuthal angles of the off-axis AVs and the radius of the centered quasi-plane wave are determined by the topological charge and the initial phase difference of the acoustic beams. With the established 16-source experimental system, the generation of multiple off-axis SAVs with a centered quasi-plane wave is demonstrated by scanning measurements of the composite field with a topological charge of 1, 2, or 3, which is also proved by the qualitatively consistent simulations for N = 16. The proposed model may be applied to multi-point vortex trapping with homogeneous particle dispersion within a finite area around the central axis. These favorable results provide the feasibility of controllable manipulation for drug particles or cells and suggest wide potential applications in the fields of sonochemistry and biomedical engineering.

Based on the analysis of the wave vector of an acoustic-vortex (AV) spanner, the radiation torque of object rotation is investigated. It is demonstrated that the rotation of an axisymmetric disk centered on the AV spanner is mainly driven by the acoustic radiation force. The radiation torque exerted on a small-radius object is inversely associated with the topological charge in the center AV, and it is enhanced significantly for a larger AV with a higher topological charge. With the sixteen-source experimental setup, radius dependencies of radiation torque for AV spanners with different topological charges are verified by quantitative laser-displacement measurements using disks with different radii. The favorable results demonstrate that the radiation torque is more applicable than the orbital angular momentum in describing the driving capability of an AV spanner and can be used as an effective tool in clinical applications to manipulate objects with a feature size at the wavelength-scale inside body.

The existing photonic switch matrices usually show the drawbacks of either a large footprint or high cross talk. Here, we propose a compact InGaAsP/InP rearrangeable nonblocking 4×4 photonic switch fabric based on 2×2 Mach-Zehnder interferometer (MZI) switch elements in a Benes architecture. Each switch element consists of two frustrated total internal reflection (TIR) couplers and TIR mirrors serving as 90° waveguide bends, forming the square layout configuration of the 2×2 MZI switches. We investigate the design parameters of the switch element and 4×4 photonic switch matrix by using FDTD and transfer matrix methods, respectively. Our analysis results show that the proposed device exhibits an ultracompact chip size of ∼340 μm×120 μm, the minimum cross talk of -23 dB in the 1.5∼1.6 μm wavelength range, the total insertion loss of ∼3.9 dB, the low electrical energy of ∼0.4 pJ/bit, and an operation speed up to 50 GHz. Experimentally, we can demonstrate the feasibility of fabricating 2×2 MZI switches and an operational low-loss trench-coupler. The enabling component of the 2×2 MZI switch can scale its pattern in the 2D directions. This as-formed compact 4×4 switch fabric can be potentially applied in large-scale InP-based photonic integrated circuits.

Although the application of high intensity focused ultrasound (HIFU) has been demonstrated to be a non-invasive treatment technology for tumor therapy, the real-time temperature monitoring is still a key issue in the practical application. Based on the temperature-impedance relation, a fixed-point magnetically induced magnetoacoustic measurement technology of treatment efficacy evaluation for tissue thermocoagulation during HIFU therapy is developed with a sensitive indicator of critical temperature monitoring in this study. With the acoustic excitation of a focused transducer in the magnetoacoustic tomography with the magnetic induction system, the distributions of acoustic pressure, temperature, electrical conductivity, and acoustic source strength in the focal region are simulated, and the treatment time dependences of the peak amplitude and the corresponding amplitude derivative under various acoustic powers are also achieved. It is proved that the strength peak of acoustic sources is generated by tissue thermocoagulation with a sharp conductivity variation. The peak amplitude of the transducer collected magnetoacoustic signal increases accordingly along with the increase in the treatment time under a fixed acoustic power. When the temperature in the range with the radial and axial widths of about ±0.46 mm and ±2.2 mm reaches 69 °C, an obvious peak of the amplitude derivative can be achieved and used as a sensitive indicator of the critical status of treatment efficacy. The favorable results prove the feasibility of real-time non-invasive temperature monitoring and treatment efficacy evaluation for HIFU ablation using the magnetically induced magnetoacoustic measurement, and might provide a new strategy for accurate dose control during HIFU therapy.

In order to improve the capability of particle trapping close to the source plane, theoretical and experimental studies on near-field multiple traps of paraxial acoustic vortices (AVs) with a strengthened acoustic gradient force (AGF) generated by a sector transducer array were conducted. By applying the integration of point source radiation, numerical simulations for the acoustic fields generated by the sector transducer array were conducted and compared with those produced by the circular transducer array. It was proved that strengthened AGFs of near-field multiple AVs with higher peak pressures and smaller vortex radii could be produced by the sector transducer array with a small topological charge. The axial distributions of the equivalent potential gradient indicated that the AGFs of paraxial AVs in the near field were much higher than those in the far field, and the distances at the near-field vortex antinodes were also proved to be the ideal trapping positions with relatively higher AGFs. With the established 8-channel AV generation system, theoretical studies were also verified by the experimental measurements of pressure and phase for AVs with various topological charges. The formation of near-field multiple paraxial AVs was verified by the cross-sectional circular pressure distributions with perfect phase spirals around central pressure nulls, and was also proved by the vortex nodes and antinodes along the center axis. The favorable results demonstrated the feasibility of generating near-field multiple traps of paraxial AVs with strengthened AGF using the sector transducer array, and suggested the potential applications of close-range particle trapping in biomedical engineering.

A novel ferrocene-containing porous organic polymer (FPOP) has been prepared by Sonogashira-Hagihara coupling reaction of 1,1′-dibromoferrocene and tetrakis(4-ethynylphenyl)silane. Compared with other polymers, the resulting polymer possesses excellent thermal stability with the decomposition temperature of 415°C and high porosity with Brunauer–Emmett–Teller (BET) surface area of 542 m2 g−1 as measured by nitrogen adsorption-desoprtion isotherm at 77 K. For applications, it shows moderate carbon dioxide uptakes of up to 1.42 mmol g−1 (6.26 wt%) at 273 K/1.0 bar and 0.82 mmol g−1 (3.62 wt%) at 298 K/1.0 bar, and hydrogen capacity of up to 0.45 mmol g−1 (0.91 wt%) at 77 K/1.0 bar, indicating that FPOP might be utilized as a promising candidate for storing carbon dioxide and hydrogen. Although FPOP possesses lower porosity than many porous polymers, the gas capacities are higher or comparable to them, thereby revealing that the incorporation of ferrocene units into the network is an effective strategy to enhance the affinity between the framework and gas.

Low-intensity focused ultrasound is a form of therapy that can have reversible acoustothermal effects on biological tissue, depending on the exposure parameters. The acoustic power (AP) should be chosen with caution for the sake of safety. To recover the energy of counteracted radial vibrations at the focal point, an accurate AP measurement method using the focal axial vibration velocity (FAVV) is proposed in explicit formulae and is demonstrated experimentally using a laser vibrometer. The experimental APs for two transducers agree well with theoretical calculations and numerical simulations, showing that AP is proportional to the square of the FAVV, with a fixed power gain determined by the physical parameters of the transducers. The favorable results suggest that the FAVV can be used as a valuable parameter for non-contact AP measurement, providing a new strategy for accurate power control for low-intensity focused ultrasound in biomedical engineering.

Surface plasmons (SPs) in ultraviolet (UV) have attracted a great deal of attention because of their emerging applications in energy resources, environmental protection, and biotechnology. In this article, the dielectric loaded surface plasmon polariton (DLSPP) properties of the Al–Al nanostructure are investigated theoretically. Sharp SP responses can be obtained in deep UV by setting an insulator grating on the aluminum film. It is found that the height of the grating element, the lattice parameter, and the filling factor can all modulate the DLSPPs of the AlO–Al nanostructure. We further find that this structure is sensitive to the embedding medium and can serve as a refractive index sensor in the UV region. The corresponding sensitivity increases with the decrease of the filling factor. The Al–Al nanostructure may be useful for medical diagnostics and biotechnology in deep UV.

Based on the radiation pattern of a planar piston transducer, the mechanisms underlying the generation of axially controllable deep-level stereoscopic multiple traps of acoustic vortices (AV) using sparse directional sources were proposed with explicit formulae. Numerical simulations for the axial and cross-sectional distributions of acoustic pressure and phase were conducted for various ka (product of the wave number and the radius of transducer) values at the frequency of 1 MHz. It was demonstrated that, for bigger ka, besides the main-AV (M-AV) generated by the main lobes of the sources, cone-shaped side-AV (S-AV) produced by the side lobes were closer to the source plane at a relatively lower pressure. Corresponding to the radiation angles of pressure nulls between the main lobe and the side lobes of the sources, vortex valleys with nearly pressure zero could be generated on the central axis to form multiple traps, based on Gor'kov potential theory. The number and locations of vortex valleys could be ...

Objective : Based on the interaction of ultrasonic excitation and magnetoelectrical induction, magneto-acousto-electrical (MAE) technology was demonstrated to have the capability of differentiating conductivity variations along the acoustic transmission. By applying the characteristics of the MAE voltage, a simplified algorithm of MAE measurement based conductivity reconstruction was developed. Methods : With the analyses of acoustic vibration, ultrasound propagation, Hall effect, and magnetoelectrical induction, theoretical and experimental studies of MAE measurement and conductivity reconstruction were performed. The formula of MAE voltage was derived and simplified for the transducer with strong directivity. MAE voltage was simulated for a three-layer gel phantom and the conductivity distribution was reconstructed using the modified Wiener inverse filter and Hilbert transform, which was also verified by experimental measurements. Results: The experimental results are basically consistent with the simulations, and demonstrate that the wave packets of MAE voltage are generated at tissue interfaces with the amplitudes and vibration polarities representing the values and directions of conductivity variations. With the proposed algorithm, the amplitude and polarity of conductivity gradient can be restored and the conductivity distribution can also be reconstructed accurately. Conclusion : The favorable results demonstrate the feasibility of accurate conductivity reconstruction with improved spatial resolution using MAE measurement for tissues with conductivity variations, especially suitable for nondispersive tissues with abrupt conductivity changes. Significance : This study demonstrates that the MAE measurement based conductivity reconstruction algorithm can be applied as a new strategy for nondestructive real-time monitoring of conductivity variations in biomedical engineering.

As a noninvasive imaging modality based on the coupling of magnetic and acoustic fields, magnetoacoustic tomography with magnetic induction (MAT-MI) has been demonstrated to have the capability of imaging the variation of conductivity distribution inside the object. However, the image resolution is still limited by the parameters of the receiver. Based on the theory of acoustic dipole, 3D equivalent source analysis was used to simulate transducer detected pressures and waveforms for MAT-MI. The influence of transducer was studied both theoretically and experimentally for a cylindrical model. It is demonstrated that large-radius transducer with strong reception pattern can detect the acoustic signals transmitted along its normal direction with sharp pressure peaks, reflecting the divergence of the induced Lorentz force. By considering the effect of acoustic attenuation and the accuracy of image reconstruction, the acoustic pressure with acceptable peak pressure ratio and improved SNR can be detected when t...

As an acoustic receiver, transducer plays a vital role in signal acquisition and image reconstruction for magnetoacoustic tomography with magnetic induction (MAT-MI). In order to optimize signal acquisition, the expressions of acoustic pressure detection and waveform collection are theoretically studied based on the radiation theory of acoustic dipole and the reception pattern of transducer. Pressure distributions are simulated for a cylindrical phantom model using a planar piston transducer with different radii and bandwidths. The proposed theory is also verified by the experimental measurements of acoustic waveform detection for an aluminum foil cylinder. It is proved that acoustic pressure with sharp and clear boundary peaks can be detected by the large-radius transducer with wide bandwidth, reflecting the differential of the induced Lorentz force accurately, which is helpful for precise conductivity reconstruction. To detect acoustic pressure with acceptable pressure amplitude, peak pressure ratio, am...

Goal: As a multiphysics imaging approach, magnetoacoustic tomography with magnetic induction (MAT-MI) works on the physical mechanism of magnetic excitation, acoustic vibration, and transmission. Methods : Based on the theoretical analysis of the source vibration, numerical studies are conducted to simulate the pathological changes of tissues for a single-layer cylindrical conductivity gradual-varying model and estimate the strengths of sources inside the model. Results : The results suggest that the inner source is generated by the product of the conductivity and the curl of the induced electric intensity inside conductivity homogeneous medium, while the boundary source is produced by the cross product of the gradient of conductivity and the induced electric intensity at conductivity boundary. Conclusion : For a biological tissue with low conductivity, the strength of boundary source is much higher than that of the inner source only when the size of conductivity transition zone is small. In this case, the tissue can be treated as a conductivity abrupt-varying model, ignoring the influence of inner source. Otherwise, the contributions of inner and boundary sources should be evaluated together quantitatively. Significance : This study provide basis for further study of precise image reconstruction of MAT-MI for pathological tissues.