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Home arrow Selected Results arrow 2013 arrow Selected Results of Basic Research
Selected Results of Basic Research
  • Thin layer organic and inorganic materials in magnetic field of MR tomograph 
  • Modified inverse solution for localization of repolarization changes using a group of dipoles
  • V2O3 nanocrystalline oxides prepared by the mechano-thermal reduction and their magnetic properties
  • Probabilistic sleep model for objective sleep quality assessment 

Result 1: Thin layer organic and inorganic materials in magnetic field of MR tomograph

Projects: VEGA 2/0090/11,  ŠPVV no. 2003SP200280203, CEKOMAT, ITMS 26240120006, APVV-0513-10, KC, ITMS 26240220073 (Ústav merania SAV)
Authors: I. Frollo, P. Andris, O. Štrbák, D. Gogola, J. Přibil, A. Krafčík, T. Dermek

Imaging of thin layers of organic and inorganic material, using magnetic resonance methods, require complicated experiment arrangement and specific imaging sequences. A mathematical model was developed, from which a plane scanning detector was constructed. Using of such a detector and sophisticated imaging procedures in the tomograph based on magnetic resonance various selected objects were tested, (e.g., oil slick, segment from weak magnetic polymer membrane, thin conductor with direct electrical current, diskette to store data or programs with visible data sectors, thin metallic coins, polymer fibers and textiles treated by magnetic nanoparticles designated for surgery, layer with biogenic magnetic nanoparticles and surgical implants. Experiments were realized on magnetic resonance tomograph 0.2 Tesla ESAOTE controlled by the computer console TECMAG.

The proposed method could be used in a variety of imaging experiments, e.g., petrochemical research, on very silky samples, textile material treated by magnetic nanoparticles for biomedicine, documents equipped with hidden magnetic domain, credit cards, banknotes, and more.




Fig. 1. Left: NMR detector with inserted plastic circular magnetic disc.
Basic dimensions: Ø1 = 25 mm, Ø2= 85 mm, thickness of the disc 0.08 mm.
Right: NMR image of the material sample - diskette with visible data sectors.



Fig. 2. Examples of imaging of commercial coins using Gradient-echo sequence. Material inhomogeneities are clearly visible



  1.   FROLLO, Ivan. Mathematical Modeling, Computation and Experimental Imaging of Thin Layer Objects by Magnetic Resonance Imaging.  Mathematical Problems in Engineering, 2013, Hindawi Publishing Corporation, vol. 2013, pp. 1-6. ISSN 1563-5147, doi: 10.1155/2013/635713, (1.383-IF2012),  In press, 2013.
  2. FROLLO, Ivan - ANDRIS, Peter - PŘIBIL, Jiří - DERMEK, Tomáš - GOGOLA, Daniel. Soft magnetic material testing using magnetic resonance imaging. In Advanced Materials Research, 2013, vol. 740, p. 618-623. ISSN 1022-6680. (WOS, Scopus, Copernicus International).
  3. ANDRIS, Peter - FROLLO, Ivan. Asymmetric spin echo sequence and requirements on static magnetic field of NMR scanner. In Measurement, 2013, vol. 46, no. 4, p. 1530-1534. ISSN 0263-2241. (1.130-IF2012).
  4. ANDRIS, Peter - FROLLO, Ivan. NMR spectroscopic imaging method for static magnetic field mapping. In Applied Magnetic Resonance, 2013, vol. 44, no. 5, p. 637-647. ISSN 0937-9347. (0.830-IF2012).
  5. ŠTRBÁK, Oliver - KOPČANSKÝ, P. - TIMKO, M. - FROLLO, Ivan. Single biogenic magnetite nanoparticle physical characteristics-A biological impact study (for MagMeet 2012 participants). In IEEE Transactions on Magnetics, 2013, vol. 49, no. 1, p. 457-462. ISSN 0018-9464. (1.422-IF2012).
  6. GOGOLA, Daniel - KRAFČÍK, Andrej - ŠTRBÁK, Oliver - FROLLO, Ivan. Magnetic resonance imaging of surgical implants made from weak magnetic materials. In Measurement Science Review, 2013, vol. 13, no. 4, p. 165-168. ISSN 1335-8871. (1.233-IF2012; WOS, Scopus, Copernicus International).

Result 2: Modified inverse solution for localization of repolarization changes using a group of dipoles


Projects: VEGA 2/0131/13, APVV-0513-10
Authors: J. Švehlíková, M. Tyšler

In the simulation study a modification of the solution of inverse problem of electrocardiology for localization of lesions with changed repolarization was proposed. While one dipole representing the lesion has been search in the original method, in the modified method it is supposed that the lesion is represented by a group (of 2-5) neighboring dipoles. Simulated difference integral maps on the torso computed as the difference between an integral map corresponding to a healthy heart and a map with local repolarization changes was used as input. Sixty six lesions of different size were modeled (24 small, 28 medium, 5/9 large/transmural). Ten realizations of noise of 10, 20, 30 and 40 dB was added to the input maps. From the results it was concluded that the localization error of the inverse solution to one dipole was stable 6± 0.3cm, 1.1 ± 0.9 cm, and 2.3 ± 1.2 cm, respectively for particular lesion sizes regardless of the noise intensity. Localization error of the inverse solution to a group of dipoles was sensitive to noise in input data but it significantly improved to 1.0 ± 0.3 cm in case of low noise of 40 dB and large/transmural lesions and was lower also in case of noise of 30 dB.












Fig. 1. Localization errors of lesions of different sizes for different levels of noise in ECG data when using single dipole (left) or a group of dipoles (right).




  1. TYSLER, Milan - SVEHLIKOVA Jana. Noninvasive finding of local repolarization changes in the heart using dipole models and simplified torso geometry. J. of Electrocardiology, 2013, vol. 46, p.284-288, ISSN (printed): 0022-0736. ISSN (electronic): 1532-8430.(1.093 IF2012).
  2. SVEHLIKOVA, Jana - LENKOVA, Jana - TYSLER, Milan: Modified Inverse Solution to One Dipole for Location of Lesions with Changed Repolarization. Computing in Cardiology 2012 (www.cinc.org); 39:841-844, ISSN 0276-6574.
  3. SVEHLIKOVA, Jana - LENKOVA, Jana - TYSLER, Milan: Inverse Localization of Various Sizes of Ischemic Lesions from Variations in Body Surface Potential Maps. In: Variability in biomedical signals. Lecture notes of the ICB seminar.  Eds. R.Maniewski, A. Liebert, O. Meste, H. Rix, Int. Centre od Biocybernetics, Polish Academy of Sciences, Warsaw, November 2012, 79-83.


Result 3: V2O3 nanokryštalické oxidy pripravené mechanochemicko-termálnou redukciou a ich magnetické vlastnosti

Projects: ASFEU projekt 26240220073 (Kompetenčné centrum pre nové materiály, pokročilé technológie a energetiku), APVV-0528-11 a VEGA 2/0020/11
Authors: P. Billik , A. Cigáň, M. Škrátek, A. Dvurečenskij, M. Majerová, R. Bystrický, J. Maňka

Nanomateriálom na báze vanádu je v posledných rokoch venovaná zvýšená pozornosť, najmä ako materiálom elektród v lítiových iónových batériách a v superkondenzátoroch s vysokou hustotou energie v rámci vývoja zásobníkov energie, napr. pre elektrotechnický a automobilový priemysel.

Bol vyvinutý nový postup prípravy V2O3 nanokryštálov v soľnej matrici Na2SO4 s využitím mechanochemicko-termálnej redukcie V2O5 a Na2SO3. V2O3 nanokryštály boli syntetizované v soľnej matrici Na2SO4. Tento nízkocenový postup sa vyznačuje iba 10 minútovým vysokoenergetickým mletím, po ktorom nasledovalo vákuové nízkoteplotné žíhanie. V2O3 nanokryštály s rozmerom 25-60 nm a dobrou morfológiou boli pripravené už pri teplote žíhania 550 °C. Tieto nanokryštály vykazujú magnetický prechod z antiferomagnetického do paramagnetického usporiadania pri 144 K. Stanovené hodnoty efektívneho magnetického momentu nanokryštálov, na základe nameraných priebehov teplotnej závislosti ich molárnej magnetickej susceptibility pri chladení v nulovom poli, boli blízke hodnote iba spinového príspevku dvoch nespárovaných elektrónov iónov vanádu.


Výsledky boli dosiahnuté v spolupráci s týmito pracoviskami: Katedra anorganickej chémie PRIF UK v Bratislave, Katedra ložiskovej geológie PRIF UK v Bratislave.




  1. BILLIK, Peter - CIGÁŇ, Alexander - ČAPLOVIČOVÁ, M. - ŠKRÁTEK, Martin - DVUREČENSKIJ, Andrej - MAJEROVÁ, Melinda - BYSTRICKÝ, Roman - ANTAL, P. - MAŇKA, Ján. V2O3 nanocrystals prepared by mechanochemical-thermal reduction and their magnetic properties. In Materials Letters, 2013, vol. 110, p. 24-26. ISSN 0167-577X. (2.224-IF2012).
  2. DVUREČENSKIJ, Andrej - BILLIK, Peter - CIGÁŇ, Alexander - BYSTRICKÝ, Roman - MAŇKA, Ján - ŠKRÁTEK, Martin - MAJEROVÁ, Melinda: Magnetic Properties of V2O3 Nanooxide Prepared Mechanochemically with and without Salt Matrix. Poster na medzinárodnej konferencii: CSMAG'13, 15th Czech and Slovak Conference on Magnetism, 17.-21. June 2013, Košice, Slovakia.


Result 4: Probabilistic sleep model for objective sleep quality assessment

Projects: VEGA 1/0503/13, MZ SR 2012/56-SAV-6

Authors: R. Rosipal


Sleep deprivation, whether from disorder or lifestyle, whether acute or chronic, poses a significant risk in day-time cognitive performance, excessive somnolence, impaired attention or decreased level of motor abilities. Sleep deprivation is closely related to sleep fragmentation often associated with short several second long arousals. Although limited studies of partial sleep restriction and sleep fragmentation have revealed important sleep indices leading to cognitive deficits, a challenging question how a typical, good quality, structure of sleep should look like remains open. To improve these results we studied, designed and evaluated a novel probabilistic sleep model. Important added value of the model is its ability to capture detailed microstructure of the sleep process at the much higher temporal resolution than the standard sleep staging models. In an extensive series of tests on healthy subjects we have shown that the model contains significantly more objective information about external measures of the sleep quality than the traditional sleep staging. We continue in the model development and additional testing, now also including a collection of sleep data of stroke patients.

Associated projects: VEGA 1/0503/13, MZ SR 2012/56-SAV-6.

Fig. 1. On the left is a diagram of the temporal probabilistic model (PSM). On the right is a sample representation of the temporal process of traditional form Rechtschaffen and Kales hypnogram (upper blue curve) and PSM form for each sleep state.



  1. ROSIPAL, Roman - LEWANDOWSKI, A. - DORFFNER, G. In search of objective components for sleep quality indexing in normal sleep. In Biological Psychology, 2013, vol. 94, no. 1, p. 210-220. ISSN 0301-0511. (CC, 3.399-IF2012).
  2. LEWANDOWSKI, A. - ROSIPAL, Roman - DORFFNER, G. On the individuality of sleep EEG spectra. In Journal of Psychophysiology, 2013, vol. 27, no. 3, p. 105-112. ISSN 0269-8803. (1.000-IF2012; WOS, Scopus).
  3. ROSIPAL, Roman. Clustering probabilistic sleep microstate curves: A functional data analysis approach. In MEASUREMENT 2013: 9th International Conference on Measurement. Editors J. Maňka, M. Tyšler, V. Witkovský, I. Frollo. - Bratislava : Institute of Measurement Science, SAS, 2013, p. 101-104. ISBN 978-80-969-672-5-4.
  4. LEWANDOWSKI, A. - ROSIPAL, Roman - DORFFNER, G. Extracting more information from EEG recordings for a better description of sleep. In Computer Methods and Programs in Biomedicine, 2012, vol. 108, no. 3, p. 961-972. ISSN 0169-2607. (CC, 1.516-IF2011).
  5. ROSIPAL, Roman. Multilevel functional clustering analysis of probabilistic sleep microstate curves. The 5th International Conference of the ERCIM Working Group on Computing & Statistics (ERCIM 2012), Oviedo, Spain, December 1 - 3, 2012.
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