Innovative treatments that actually involve damaging certain parts of the brain may represent some patients’ only chance for recovery.

In this paper we present the numerical simulation-based design of a new microfluidic device concept for electrophoretic mobility and (relative) concentration measurements of dilute mixtures. The device enables stationary focusing points for each species, where the locally applied pressure driven flow (PDF) counter balances the species’ electrokinetic velocity. The axial location of the focusing point, along with the PDF flowrate and applied electric field reveals the electrokinetic mobility of each species. Simultaneous measurement of the electroosmotic mobility of an electrically neutral specie can be utilized to calculate the electrophoretic mobility of charged species. The proposed device utilizes constant sample feeding, and results in time-steady measurements. Hence, the results are independent of the initial sample distribution and flow dynamics. In addition, the results are insensitive to the species diffusion for large Peclet number flows (Pe > 400), enabling relative concentration measurement of each specie in the dilute mixture.

The paper deals with the problem of acoustic correction in historic opera theatres with the auditorium layout in the form of a horseshoe with deep underbalcony cavities limited with a semicircular wall surface. Both geometry of the cavities and excessive sound absorption determine acoustic phenomena registered in this area of the hall. The problem has been observed in the Theatre of Opera and Ballet in Lviv, Ukraine, where acoustic tests were carried out, simulation calculations performed, and finally a diffusion panel worked out designed for the rear wall of the underbalcony space. Acoustic measurements carried out after installation of the diffusers revealed favourable changes in the sound strength factor G within the range of medium and high frequencies in the underbalcony and auditorium centre area. By replacing textile tapestry with diffusion panels, a significant reduction of sound absorption was achieved for the frequency range above 1 kHz and an increase of uniformity of acoustic parameters registered in the hall. The method presented in the paper can be applied in historic halls of the similar type as well as contemporary rooms where there is a need for correction of acoustic flaws related to sound focusing or the echo effect.

The study of liquid crystalline assemblies, with an emphasis on biological phenomena, is now accessible using newly developed microdevices integrated with X-ray analysis capability. Many biological systems can be described in terms of gradients, mixing, and confinement, all of which can be mimicked with the use of appropriate microfluidic designs. The use of hydrodynamic focusing creates well-defined mixing conditions that vary depending on parameters such as device geometry, and can be quantified with finite element modelling.We describe experiments in which geometry and strain rate induce finite changes in liquid crystalline orientation. We also demonstrate the online supramolecular assembly of lipoplexes. The measurement of lipoplex orientation as a function of flow velocity allows us to record a relaxation process of the lipoplexes, as evidenced by a remarkable 4-fold azimuthal symmetry. All of these processes are accessible due to the intentional integration of design elements in the microdevices.

Based on the ray acoustic model, a new relationship between the radiation force and the acoustic power is studied for a rectangular weakly focusing transducer. The effect of pressure reflection coefficient on this model is discussed. For a totally absorbing target, an approximate closed-form expression is also derived and the performance of this model is compared with that of the far-field integration model. The numerical results show that the agreement is excellent with these two models, which can be both used for correction of measured results, but the formula based on the ray acoustic model can be applied more widely in practice because of its simpler expression. The experimental results show further the effectiveness of the relationship between radiation force and acoustic power for rectangular weakly focusing transducer based on the ray acoustic model. The results presented in this paper are important for application of ultrasound transducers in therapy.

This paper presents the results of acoustic field distribution simulations for the 1024-element ultrasonic ring array intended for the diagnosis of female breast tissue with the use of ultrasound tomography. For the purpose of analysing data, all acoustic fields created by each elementary transducer were combined. The natural position of the focus inside the ultrasonic ring array was changed by altering activation time of individual transducers in sectors consisting of 32, 64, and 128 ultrasonic transducers. Manipulating the position of the focus inside the array will allow to concentrate the ultrasonic beam in a chosen location in the interior space of the ring array. The goal of this research is to receive the best possible quality of images of cross-sections of the female breast. The study also analysed the influence of the acoustic field distribution on the inclination of the beam. The results will enable to choose an optimal focus and an optimal number of activated transducers.

In order to find the defects in ferromagnetic materials, a non-contact harmonic detection method is proposed. According to the principle of frequency modulated carrier wave, a tunnel magneto resistance harmonic focusing vector array detector was designed which radiates lower and higher frequency electromagnetic waves through the coil array to the detection targets. We use bistable stochastic resonance to enhance the energy of collected weak target signal and apply quantum computation and a Sobol low deviation sequence to improve genetic algorithm performance. Then we use the orthogonal phase-locked loop to eliminate the intrinsic background excitation field and tensor calculations to fuse the vector array signal. The finite element model of array detector and the magnetic dipole harmonic numerical model were also established. The simulation results show that the target signal can be identified effectively, its focusing performance is improved by 2 times, and the average signal-to-noise ratio is improved by 9.6 times after the algorithm processing. For the experiments, we take Q235 steel pipeline as the object to realize the recognition of three defects. Compared with the traditional methods, the proposed method is more effective for ferromagnetic materials defects detection.

The emergence of high-intensity focused ultrasound applications brings great potential to establish noninvasive therapeutic treatment in place of conventional surgery. However, the development of ultrasonic technology also poses challenges to the design and manufacture of high-power ultrasound transducers with sufficient acoustic pressure. Here, the design of a sector vortex Archimedean spiral phased array transducer that is able to enhance focal acoustic pressure is proposed by maximizing the filling factor of the piezoelectric array. The transducer design was experimentally verified by hydrophone measurements and matched well with acoustic simulation studies. The focal deflection was shown to be feasible up to ±9 mm laterally and up to ±20 mm axially, where the effective focal acoustic pressure can be maintained above 50% and the level of the grating lobe below 30%. Furthermore, a homogeneous pressure distribution without secondary focus was observed in the pre-focal region of the transducer. The rational design of a high-intensity focused ultrasound transducer indicates promising development in the treatment of deep tissue thermal ablation for clinical applications.

This work reports on the investigation of homogeneity of the inside of indium micro-bumps/ columns placed on Ti/Pt/Au under bump metallisation. This is very important for connection resistivity, long-time durability, and subsequent hybridisation process (e.g., die-bonding). Gold reacts with indium to form intermetallic alloys with different chemo-physical parameters than pure indium. The geometrical and structural parameters of intermetallic alloys were analysed based on transmission electron microscope images. Distribution of elements in the investigated samples was determined using the transmission electron micro-scope with energy dispersive spectroscopy method. A thickness of intermetallic alloy was 1.02 μm and 1.67 μm in non-annealed (A) and annealed (B) indium columns, respectively. The layered and column-like interior structure of alloys was observed for both samples, respectively, with twice bigger grains in sample B. The graded chemical composition of Au-In intermetallic alloy was detected for the non-annealed In columns in contrast to the constant composition of 40% of Au and 60% of In for the annealed sample B. The atomic distribution has a minor impact on the In column mechanical stability. A yield above 99% of an In column with a 25 µm diameter and a 11 µm height is possible for a uniform columnar structure of intermetallic alloy with a thickness of 1.67 μm.

Thermal self-action of an acoustic beam with one discontinuity or several shock fronts is studied in a Newtonian fluid. The stationary self-action of a single sawtooth wave with discontinuity (or some integer number of these waves), symmetric or asymmetric, is considered in the cases of self-focusing and self- defocusing media. The results are compared with the non-stationary thermal self-action of the periodic sound. Thermal self-action of a single shock wave which propagates with the various speeds is considered.

The paper presents an overview of theoretical aspects of ultrasound image reconstruction techniques based on the circular Radon transform inversion. Their potential application in ultrasonography in a similar way as it was successfully done in the x-ray computer tomography is demonstrated. The methods employing Radon transform were previously extensively explored in the synthetic aperture radars, geophysics, and medical imaging using x-ray computer tomography. In this paper the main attention is paid to the ultrasound imaging employing monostatic transmit-receive configuration. Specifically, a single transmit and receive omnidirectional source placed at the same spatial location is used for generation of a wide-band ultrasound pulse and detection of back-scattered waves. The paper presents derivation of the closed-form solution of the CRT inversion algorithms by two different approaches: the range-migration algorithm (RMA) and the deconvolution algorithm (DA). Experimentally determined data of ultrasound phantom obtained using a 32-element 5 MHz linear transducer array with 0.48 mm element pitch and 0.36 mm element width and 5 mm height, excited by a 2 sine cycles burst pulse are used for comparison of images reconstructed by the RMA, DA, and conventional synthetic aperture focusing technique (SAFT). It is demonstrated that both the RMA and SAFT allow better lateral resolution and visualization depth to be achieved as compared to the DA approach. Comparison of the results obtained by the RMA method and the SAFT indicates slight improvement of the lateral resolution for the SAFT of approximately 1.5 and 1.6% at the depth of 12 and 32 mm, respectively. Concurrently, however, the visualization depth increase for the RMA is shown in comparison with the SAFT. Specifically, the scattered echo amplitude increase by the factor of 1.36 and 1.12 at the depth of 22 and 32 mm is demonstrated. It is also shown that the RMA runs about 30% faster than the SAFT and about 12% faster than the DA method

A sonic crystal consists of a finite-size periodic array of scatters embedded in a background material. One of the fascinating properties of sonic crystals is the focusing phenomenon. In this study, the near field focusing effect of a solid-air 2D sonic crystal lens with a square lattice configuration is investigated in the second frequency band. The band structure and equifrequency contour of the crystal are analyzed to reveal the dispersion of an acoustic wave on the crystal structure. The frequency dependence of the acoustic wave focalization by the sonic crystal flat lens is demonstrated via Finite Difference Time Domain simulation results and experimental measurements.

Due to the difficulty of detecting traces of organic acid mixture in an aqueous sample and the complexity of resolving UV-Vis spectra effectively, a combinatory method based on a self-made radical electric focusing solid phase extraction (REFSPE) device, UV-Vis detection and partial least squares (PLS) calculation is proposed here. In this study, REFSPE was used to enhance the extraction process of analytes between the aqueous phase and the membrane phase to enrich the trace of mixed organic acid efficiently. Then, the analytes, which were eluted from the adsorption film by ethanol with the assistance of an ultrasonic cleaning machine, were detected with UV-Vis spectrophotometry. After that, the PLS method was introduced to solve the problem of overlapping peaks in UV-Vis spectra of mixed substances and to quantify each compound. The linearly dependent coefficients between the predicted value of the model and the actual concentration of the sample were all higher than 0.99. The limit values of detection for benzoic acid, phthalic acid and p-toluene sulfonic acid were found at 9.9 µg/L, 12.2 µg/L and 13.8 µg/L with the relative recovery values between 84.8% and 117.9%. The RSD (n = 20) values of each component are 1.17%, 1.11% and 0.86%, respectively. Therefore, the proposed combined method can determine traces of complex materials in an aqueous sample efficiently and has wonderful potential applications.