Mikrosekundinių stiprių magnetinių laukų formuotų impulsų generatorių tyrimas

Microsecond high magnetic field shaped pulse generators are investigated in the dissertation. High magnetic field technologies, circuit transition processes and the pulse shaping technique are analysed. Two prototypes of the high magnetic field generators are developed, one of them with asymmetric pulse shape with amplitude over 10 T, the rise time of 200 s and decay time of 800 s was applied for express calibration of the magnetic field sensors. Another generator generates repetitive microsecond high magnetic field square shaped pulses with amplitude up to 5 T and duration of 3–25 s. Such generator has been applied to investigate the response of the biological objects to high-pulsed magnetic fields. The dissertation consists of three parts including introduction, 3 chapters, conclusions and references. The introduction reveals the investigated problem, importance of the thesis and the object of research and describes the purpose and tasks of the paper, research methodology, scientific novelty, the practical significance of results examined in the paper and defended statements. Author’s publications on the subject of the dissertation and conference presentations are supplied. Chapter 1 revises scientific articles related to the subject of the dissertation. The analysis of the magnetic field generation technology, devices used in magnetic field generators and microinductors are presented. The behaviour of the manganite and biological materials in high-pulsed magnetic fields are described. Conclusions and the tasks of dissertation are formed. Chapter 2 describes the structure of the high magnetic field generators prototypes. High magnetic field generator, consisting from capacitor bank, crowbar circuit and SCR switch is presented. Magnetic field distribution and Joule heating in multilayer inductors are analysed. High repetitive magnetic field generator based on MOSFET switch is presented. Transient processes in generator circuits are analysed. Microinductor field distribution and Joule heating are presented. Conclusions are formed. Chapters 3 is focused on the investigation of the magnetoresistive magnetic field sensors and the biological objects behaviour in the microsecond pulsed magnetic fields. The experimental results of the express calibration using one pulse technique of the magnetoresistive sensors and biological objects response in high magnetic fields are presented. Research results related to the dissertation subject are published in 7 scientific articles; 5 articles – in Thomson Reuters Web of Science database journals with impact factor, 2 – in others international (IndexCopernicus and IEEE/IEE) database journals, 7 presentations on the subject have been done in the conferences at national and international level

High magnetic field generator of sub-microsecond duration

The article describes the possibility of generating a micro and sub-microsecond magnetic impulse reaching 1–10 T, investigates various configurations of microcoils and discusses the principal circuit of a magnetic field impulse generator of microsecond duration. The transient processes of current, temperature and magnetic field are calculated applying the finite element method. Article in Lithuanian. Mikrosekundinės trukmės magnetinių impulsų generatorius Santrauka. Nagrinėjamas mikrosekundinės ir submikrosekundinės trukmės magnetinių impulsų, siekiančių 1–10 T, generavimas. Pateikta mikrosekundės trukmės magnetinių impulsų generatoriaus, kuris susideda iš mikroritės, mažą parazitinį induktyvumą turinčio kondensatoriaus ir greitų didelės galios MOSFET raktų principinė valdymo schema. Pereinamiesiems srovės, įtampos, elektromagnetinio lauko ir termodinaminiams vyksmams gauti taikomi analizinis ir baigtinių elementų skaičiavimo metodai. Straipsnyje pateikti elektromagnetinio lauko pasiskirstymo skaičiavimo rezultatai. Reikšminiai žodžiai: submikrosekundinis, baigtinių elementų metodas, magnetinis laukas, MOSFET, IGBT, kondensatorius, mikroritė

The effects of changes in physiological and biochemical parameters in elite male professional basketball players during preseason and competition period

The changes in biochemical and physiological parameters have the influence to athletes sport performance, during preseason and competition stage. Studying blood biochemical parameters changes, in different stages of preparation, there are possibility to prevent occur of injury and also improve athlete performance. Hypothesis. We assume that changes in biochemical parameters during different stages of preparation can influence physiological tests results and athletes performance during competiion. The aim – to determine and compare the effects of changes in physiological and biochemical parameters in elite male professional basketball players during preseason and competition period. Tasks: 1. To determine biochemical blood parameters of elite basketball players, and analyse their alternation during preseason and competition stage. 2. To determine physiological tests results of elite basketball players, and analyse their alternation during preseason and competition stage. 3. To determine correlation between physiological and biochemical blood parameters, during different stages of training. Subjects: 10 professional basketball players took part in the research: (age 28,6 ± 4,88 y.; height – 200,5 ± 8,33 cm; weight – 99,5 ± 8,5 kg; professional experience – 11,6 ± 4,14 y.). Six of the subjects are members of Lithuanian National basketball team, they participated in Olympic Games, World and Europe championships. Two of the subjects played in the strongest basketball league - NBA. Conslusions: 1. The changes of following biochemical parameters: ceratine kinase concentration, calcium and eosinophils levels in blood of elite male basketball players during preseason and competition stage. 2. Explosive muscle contraction power and power endurance parameters had a tendency to decrease, during preseason stage for elite male basketball players. During competition stage following parameters reached highest values, comparing with preseaso. 3. The changes in ceratine kinase concentration in blood, had the significant influence for explosive muscle contraction power and power endurance for elite male basketball players during preseason and competition stag

Investigation of microcoils for high magnetic field generation

Microcoils design for high pulsed magnetic field generation is described. A possibility to generate micro and sub-microsecond magnetic field pulses in 1-10 T range is analyzed. Pulsed facilities consisting of high voltage power supply, low self-inductance capacitor bank and fast high voltage solid state switches connected in parallel and in series are able to generate high power 1 kA, 0,5-1,0 ms pulses. Three different prototypes of single, dual and multiturn microcoils are investigated. Analytical and finite element methods are used for modelling of transient electromagnetic and thermodynamic processes. Computer simulation results of current density, thermal overloads and calculations of axial magnetic flux density are presented and recommendations for further experiments are offered

The investigation of 3D magnetic field distribution in multilayer coils

The investigation of magnetic field distribution via x-y-z directions of multilayer coils has been carried out. Finite elements method was used for numerical simulation of magnetic field components. The model was verified experimentally using experimental PC controlled equipment. The control algorithm for automatic measurements was developed using LabView programming package. It allows to map a magnetic field at any point over any surface moving a 3-axis magnetic probe through a three dimensional volume while measuring the three orthogonal components of magnetic field strength at designated points and magnetic field distribution profiles can be plotted. The experimental and simulation results were compared and acceptable compliance has been achieved. The results provide a possibility to forecast parameters of multilayer coils avoiding expensive and long lasting experiments

Исследование 3D распределения магнитного поля в многослойных катушках

The investigation of magnetic field distribution via x-y-z directions of multilayer coils has been carried out. Finite elements method was used for numerical simulation of magnetic field components. The model was verified experimentally using experimental PC controlled equipment. The control algorithm for automatic measurements was developed using LabView programming package. It allows to map a magnetic field at any point over any surface moving a 3-axis magnetic probe through a three dimensional volume while measuring the three orthogonal components of magnetic field strength at designated points and magnetic field distribution profiles can be plotted. The experimental and simulation results were compared and acceptable compliance has been achieved. The results provide a possibility to forecast parameters of multilayer coils avoiding expensive and long lasting experiments.Lietuviška santrauka. Pateikta daugiasluoksnės ritės magnetinio lauko pasiskirstymo x-y-z koordinačių sistemoje analizė. Taikant baigtinių elementų metodą buvo atlikta skaitinė imitacija magnetinio lauko pasiskirstymui nustatyti. Rezultatams patvirtinti buvo sukurtas kompiuterio valdomas eksperimentinis stendas. Stendo valdymo algoritmas parašytas LabView programinio paketo aplinkoje. Matavimo stendas su erdvėje judančiu x-y-z magnetinio lauko jutikliu įgalina išmatuoti magnetinio lauko pasiskirstymą tam tikroje erdvėje. Eksperimentiniai rezultatai buvo lyginami su skaitmeniniais ir pasiektas pakankamas rezultatų tikslumas. Pasiūlyta modelį bei gautus rezultatus taikyti daugiasluoksnių ričių konstrukcijos analizei ir projektavimui

Finite element method analysis of microfluidic channel with integrated dielectrophoresis electrodes for biological cell permeabilization and manipulation

The microfluidic channel with a planar inductive microcoil for the cell membrane permeabilization and the integrated planar electrodes for cell dielectrophoretic manipulation is proposed and analyzed in the study. The analyzed setup is based on the dielectrophoretic entrapment of the biological cell followed by membrane permeabilization using high pulsed magnetic field. The finite element method analysis of the DEP force and the generated pulsed magnetic field is performed. Based on finite element method analysis the potential applications of the setup in the fields of drug delivery, biomedicine and biotechnology are discussed

Membrane permeabilization of mammalian cells using bursts of high magnetic field pulses

Background Cell membrane permeabilization by pulsed electromagnetic fields (PEMF) is a novel contactless method which results in effects similar to conventional electroporation. The non-invasiveness of the methodology, independence from the biological object homogeneity and electrical conductance introduce high flexibility and potential applicability of the PEMF in biomedicine, food processing, and biotechnology. The inferior effectiveness of the PEMF permeabilization compared to standard electroporation and the lack of clear description of the induced transmembrane transport are currently of major concern. Methods The PEMF permeabilization experiments have been performed using a 5.5 T, 1.2 J pulse generator with a multilayer inductor as an applicator. We investigated the feasibility to increase membrane permeability of Chinese Hamster Ovary (CHO) cells using short microsecond (15 µs) pulse bursts (100 or 200 pulses) at low frequency (1 Hz) and high dB/dt (>106 T/s). The effectiveness of the treatment was evaluated by fluorescence microscopy and flow cytometry using two different fluorescent dyes: propidium iodide (PI) and YO-PRO®-1 (YP). The results were compared to conventional electroporation (single pulse, 1.2 kV/cm, 100 µs), i.e., positive control. Results The proposed PEMF protocols (both for 100 and 200 pulses) resulted in increased number of permeable cells (70 ± 11% for PI and 67 ± 9% for YP). Both cell permeabilization assays also showed a significant (8 ± 2% for PI and 35 ± 14% for YP) increase in fluorescence intensity indicating membrane permeabilization. The survival was not affected. Discussion The obtained results demonstrate the potential of PEMF as a contactless treatment for achieving reversible permeabilization of biological cells. Similar to electroporation, the PEMF permeabilization efficacy is influenced by pulse parameters in a dose-dependent manner