Associating behaviour of pure polar liquids : dielectric properties of caprylic acid

The associating behaviour of liquid caprylic acid has been studied by the determination of its dielectric properties. Experimental results of measurements of dielectric permittivity are reported. The molecular correlation factor was obtained with reference to the Kirkwood-Fröhlich theory and compared with the Abbott-Bolton model for non spherical molecules from above the MP to 392 K. On going from low to high temperature, the correlation factor increases from 0.2 to 0.5 and this, together with the increase of the static permittivity, suggests that the number of dimers in the liquid phase decreases with increasing temperature. A discussion of the associating behaviour of caprylic acid is reported, in view of a recent model for treating molecular systems in which dimerization occurs. According to this model a further correlation factor is introduced, besides that prescribed by the Kirkwood-Fröhlich theory, to account for correlation among dipole moments carried by monomers. This correlation factor for monomers calculated at room temperature, indicates the existence of a prevailing antiparallel order among monomers

Optimization of the MIT field exciter by a multiobjective design

This paper deals with the shape design of the excitation unit of a magnetic induction tomography (MIT) system by means of a procedure of multiobjective design. As a result of the proposed method, a set of optimal geometries of the basic excitation structure was found

The μ-BiMO method for needle pair optimization in ECT

This paper shows the optimization of the geometry of the needles for Electrochemotherapy in terms of position, size and applied voltage. The new \u3bc-BiMO optimization algorithm based on Finite Element Analyses is applied. The goal is to improve the electric field distribution in non-homogeneous tissues. In order to visualize the electroporation efficiency in terms of electric field distribution, experimental results are also shown

Pulsed electromagnetic field with temozolomide can elicit an epigenetic pro-apoptotic effect on glioblastoma T98G cells

Treatment with pulsed electromagnetic fields (PEMFs) is emerging as an interesting therapeutic option for patients with cancer. The literature has demonstrated that low-frequency/low-energy electromagnetic fields do not cause predictable effects on DNA; however, they can epigenetically act on gene expression. The aim of the present work was to study a possible epigenetic effect of a PEMF, mediated by miRNAs, on a human glioblastoma cell line (T98G). We tested a PEMF (maximum magnetic induction, 2 mT; frequency, 75 Hz) that has been demonstrated to induce autophagy in glioblastoma cells. In particular, we studied the effect of PEMF on the expression of genes involved in cancer progression and a promising synergistic effect with temozolomide, a frequently used drug to treat glioblastoma multiforme. We found that electromagnetic stimulation in combination with temozolomide can elicit an epigenetic pro-apoptotic effect in the chemo- and radioresistant T98G glioblastoma cell line

Electric field distribution study in inhomogeneous biological tissues

Most solid tumors are inhomogeneous, because of the different types of cells present, different tissues and fat, etc, along with irregular vascularization, pH variation, and heterogeneous oxygen concentration. It is of interest to study the electric field distribution when electrochemotherapy is administered. The variations in the physical and hence the electrical properties, such as the resistance (or conductance), will vary, and parts of the tumor might not get the same electric field and hence will not have the required or the desired efficacy. In this study, the effect of tissue inhomogeneity is explored using potato and apple tissue samples. For this purpose, agar gel and other tissue mimic materials are used to create the inhomogeneity and pulsed to study the effect of electrical pulses. In addition, the electric field distribution is studied using a numerical model to evaluate the effect of tissue inhomogeneity in terms of electric field distribution when electroporation is applied to permeabilize cells, for enhanced drug uptake. The electric field is evaluated by means of finite element analysis and is compared with the distribution found in a phantom model. Good correlation is obtained between the experimental and simulation results. This research has the potential to study the real tumor inhomogeneity conditions

Virtual Reality-Based Training: Case Study in Mechatronics

This paper introduces, explains and illustrates real-life application of virtual training tool for electrical engineering education. The tool gives users the opportunity to interact with and manipulate 3D models of authentic devices. The users have a possibility to compare structural differences between devices, assemble and disassemble the machines and test them under extreme conditions, all of which would not be possible while working with a real device. The 3D devices are fully operational allowing the users to interact with them on every level, including analysis of impact of supply conditions i.e. modify voltage and frequency of a particular motor and monitor changes in performance while still operating. The main goal of this research was to evaluate effectiveness and educational values of the proposed tool. Early studies and feedback from educators and students prove this tool to be a great assistance to process of education, facilitating knowledge acquisition and providing an innovative way to put theory into practice

Synthesizing sources in magnetics: a benchmark problem

Purpose: Inverse problems in electromagnetism, namely, the recovery of sources (currents or charges) or system data from measured effects, are usually ill-posed or, in the numerical formulation, ill-conditioned and require suitable regularization to provide meaningful results. To test new regularization methods, there is the need of benchmark problems, which numerical properties and solutions should be well known. Hence, this study aims to define a benchmark problem, suitable to test new regularization approaches and solves with different methods. Design/methodology/approach: To assess reliability and performance of different solving strategies for inverse source problems, a benchmark problem of current synthesis is defined and solved by means of several regularization methods in a comparative way; subsequently, an approach in terms of an artificial neural network (ANN) is considered as a viable alternative to classical regularization schemes. The solution of the underlying forward problem is based on a finite element analysis. Findings: The paper provides a very detailed analysis of the proposed inverse problem in terms of numerical properties of the lead field matrix. The solutions found by different regularization approaches and an ANN method are provided, showing the performance of the applied methods and the numerical issues of the benchmark problem. Originality/value: The value of the paper is to provide the numerical characteristics and issues of the proposed benchmark problem in a comprehensive way, by means of a wide variety of regularization methods and an ANN approach