Assoc. Prof. Dr. Libor Machala

2011

• L. Machala, J. Tucek, and R. Zboril, “Polymorphous Transformations of Nanometric Iron(III) Oxide: A Review,” CHEMISTRY OF MATERIALS, vol. 23, iss. 14, pp. 3255-3272, 2011.
  [Bibtex]

  @article ISI:000292850700001,
  Author = Machala, Libor and Tucek, Jiri and Zboril, Radek,
  Title = Polymorphous Transformations of Nanometric Iron(III) Oxide: A Review,
  Journal = CHEMISTRY OF MATERIALS,
  Year = 2011,
  Volume = 23,
  Number = 14,
  Pages = 3255-3272,
  Month = JUL 26,
  Abstract = There is great interest in iron oxides, especially in nanosized form,
     for both fundamental and practical reasons. Because of its polymorphism,
     iron(III) oxide (ferric oxide, Fe(2)O(3)) is one of the most interesting
     and potentially useful phases of the iron oxides. Each of the four
     different known crystalline Fe(2)O(3) polymorphs (alpha-, beta-, gamma-,
     and epsilon-Fe(2)O(3)) has unique biochemical, magnetic, catalytic, and
     other properties that make it suitable for specific technical and
     biomedical applications. High temperature treatment is a key step in
     most syntheses of iron(III) oxides but often triggers polymorphous
     transformations that result in the formation of undesired mixtures of
     Fe(2)O(3) polymorphs. It is therefore important to control the
     parameters that induce polymorphous transformations when seeking to
     prepare a given Fe(2)O(3) polymorph as a single phase; identifying and
     understanding these parameters is a major challenge in the study of the
     polymorphism of solid compounds. This review discusses the dependence of
     the mechanism and kinetics of the polymorphous transformations of
     Fe(2)O(3) on the intrinsic properties of the material (polymorph
     structure, particle size, particle morphology, surface coating, particle
     aggregation, incorporation of particles within a matrix) and external
     parameters of synthetic and/or natural conditions such as temperature,
     atmosphere, and pressure. The high-temperature and high-pressure induced
     transformations of Fe(2)O(3) are reviewed in detail. In addition, the
     question of whether different Fe(2)O(3) polymorphs are formed
     sequentially or simultaneously during thermal processes is discussed
     extensively, with reference to the experimental results that have been
     invoked to support these two different mechanisms. The use of selected
     analytical tools in studying the polymorphous transformations of
     Fe(2)O(3) is also discussed, with particular emphasis on in situ
     approaches. Finally, key objectives for future research in this area are
     highlighted: (i) the development of more sophisticated kinetic control
     of the gamma-Fe(2)O(3) -> epsilon-Fe(2)O(3) phase transformation; (ii)
     investigation of particle morphology changes during the polymorphous
     transformations of Fe(2)O(3); and (iii) the study of high-pressure
     induced phase transformations of Fe(2)O(3) polymorphs other than
     alpha-Fe(2)O(3).,
  DOI = 10.1021/cm200397g,
  ISSN = 0897-4756,
  Unique-ID = ISI:000292850700001,
  

2010

• M. Dobes, L. Machala, and T. Fuerst, “Blurred image restoration: A fast method of finding the motion length
  and angle,” DIGITAL SIGNAL PROCESSING, vol. 20, iss. 6, pp. 1677-1686, 2010.
  [Bibtex]

  @article ISI:000280696400016,
  Author = Dobes, Michal and Machala, Libor and Fuerst, Tomas,
  Title = Blurred image restoration: A fast method of finding the motion length
     and angle,
  Journal = DIGITAL SIGNAL PROCESSING,
  Year = 2010,
  Volume = 20,
  Number = 6,
  Pages = 1677-1686,
  Month = DEC,
  Abstract = Motion blur in photographic images is a result of camera movement or
     shake. Methods such as Blind Deconvolution are used when information
     about the direction and size of blur is not known. Restoration methods,
     such as Lucy and Richardson or Wiener reconstruction use information
     about the direction and size of the blur in the deconvolution kernel
     (called Point Spread Function - PSF). Correct and fast determination of
     the direction and size of blur improves the quality of restoration and
     it can substantially reduce the computational time. In this article, a
     fast method for finding the direction and size of the blur automatically
     is presented. The method is based on computation of the power spectrum
     of the image gradient in the frequency domain. The method has achieved
     good results on both types of images: artificially blurred and naturally
     blurred (by the camera shake). (C) 2010 Elsevier Inc. All rights
     reserved.,
  DOI = 10.1016/j.dsp.2010.03.012,
  ISSN = 1051-2004,
  Unique-ID = ISI:000280696400016,
  

• J. Frydrych, L. Machala, M. Hermanek, I. Medrik, M. Mashlan, J. Tucek, J. Pechousek, and V. K. Sharma, “A nanocrystalline hematite film prepared from iron(III) chloride
  precursor,” THIN SOLID FILMS, vol. 518, iss. 21, pp. 5916-5919, 2010.
  [Bibtex]

  @article ISI:000280989100008,
  Author = Frydrych, Jiri and Machala, Libor and Hermanek, Martin and Medrik, Ivo
     and Mashlan, Miroslav and Tucek, Jiri and Pechousek, Jiri and Sharma,
     Virender K.,
  Title = A nanocrystalline hematite film prepared from iron(III) chloride
     precursor,
  Journal = THIN SOLID FILMS,
  Year = 2010,
  Volume = 518,
  Number = 21,
  Pages = 5916-5919,
  Month = AUG 31,
  Abstract = This paper deals with a simple and low-cost method developed to deposit
     hematite (alpha-Fe(2)O(3)) layers on a fluorine-doped tin oxide (FTO/F
     center dot SnO(2)) substrate by thermal decomposition of solid iron(III)
     chloride hexahydrate (FeCl(3) 6H(2)O) Deposition procedure takes place
     through chemical intermediate iron(III) oxide chloride (FeOCl) film. A
     crucial influence of atmosphere dynamics involved in the calcination
     process of FeOCl has been observed As-deposited films were characterized
     by means of Conversion Electron Mossbauer Spectroscopy (CEMS), Grazing
     Angle X-Ray Diffractometry (GAXRD), Atomic Force Microscopy (AFM),
     Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX)
     analysis Final nanocrystalline hematite film with a cactus-field-like
     design consists of 20 nm thick porous crystal plates. A process of
     hematite doping by tin atoms from substrate coating is also discussed
     (C) 2010 Elsevier B V. All rights reserved.,
  DOI = 10.1016/j.tsf.2010.05.081,
  ISSN = 0040-6090,
  Unique-ID = ISI:000280989100008,
  

• R. Urbanova, V. Prochazka, L. Raida, A. Hlusi, M. Pecuchova, T. Papajik, K. Indrak, D. Adamova, and L. Machala, “TOXOPLASMOSIS IN CNS: OPPORTUNISTIC INFECTION WITH DIFFICULT
  DIAGNOSABILITY IN A PATIENT WITH IDIOPATIC THROMBOCYTOPENIC PURPURA
  TREATED WITH IMMUNOSUPPRESSIVES ON A LONG-TERM BASIS,” HAEMATOLOGICA-THE HEMATOLOGY JOURNAL, vol. 95, iss. 2, pp. 1911, 2010.
  [Bibtex]

  @article ISI:000279051302540,
  Author = Urbanova, R. and Prochazka, V. and Raida, L. and Hlusi, A. and
     Pecuchova, M. and Papajik, T. and Indrak, K. and Adamova, D. and
     Machala, L.,
  Title = TOXOPLASMOSIS IN CNS: OPPORTUNISTIC INFECTION WITH DIFFICULT
     DIAGNOSABILITY IN A PATIENT WITH IDIOPATIC THROMBOCYTOPENIC PURPURA
     TREATED WITH IMMUNOSUPPRESSIVES ON A LONG-TERM BASIS,
  Journal = HAEMATOLOGICA-THE HEMATOLOGY JOURNAL,
  Year = 2010,
  Volume = 95,
  Number = 2,
  Pages = 1911,
  Month = JUN,
  Note = 15th Annual Meeting of the European-Hematology-Association, Barcelona,
     SPAIN, JUN 10-13, 2010,
  Organization = European Hematol Assoc,
  ISSN = 0390-6078,
  Unique-ID = ISI:000279051302540,
  

2009

• C. Park, J. Walker, R. Tannenbaum, A. E. Stiegman, J. Frydrych, and L. Machala, “Sol-Gel-Derived Iron Oxide Thin Films on Silicon: Surface Properties and
  Interfacial Chemistry,” ACS APPLIED MATERIALS & INTERFACES, vol. 1, iss. 9, pp. 1843-1846, 2009.
  [Bibtex]

  @article ISI:000270363600001,
  Author = Park, Chi-dong and Walker, Jeremy and Tannenbaum, Rina and Stiegman, A.
     E. and Frydrych, J. and Machala, L.,
  Title = Sol-Gel-Derived Iron Oxide Thin Films on Silicon: Surface Properties and
     Interfacial Chemistry,
  Journal = ACS APPLIED MATERIALS \& INTERFACES,
  Year = 2009,
  Volume = 1,
  Number = 9,
  Pages = 1843-1846,
  Month = SEP,
  Abstract = Uniform high-quality iron oxide thin films can be formed from the spin
     coating of iron oxide/hydroxide sol-gels on a silicon substrate. Thermal
     processing of the films at temperatures of similar to 300 degrees C
     results in the transformation of films into a ternary layered structure
     with Iron oxide, Fe(2)O(3), at the surface, characterized by Mossbauer
     spectroscopy. and reduced Metallic iron characterized by depth profiling
     of the surface by X-ray photoelectron spectroscopy as a function of
     Ar(+) etching. Imaging of the etched surface by scanning electron
     microscopy reveals two distinct regions at the interface, nanoparticles
     that are very iron-rich separated by an unstructured region that is
     somewhat less iron-rich. The results demonstrate a synthetic protocol
     for the spontaneous formaton of a ternary layered structure from a
     simple one-step preparation.,
  DOI = 10.1021/am900362x,
  ISSN = 1944-8244,
  Unique-ID = ISI:000270363600001,
  

• L. Machala, R. Zboril, V. K. Sharma, J. Filip, D. Jancik, and Z. Homonnay, “Transformation of Solid Potassium Ferrate(VI) (K(2)FeO(4)): Mechanism
  and Kinetic Effect of Air Humidity,” EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, iss. 8, pp. 1060-1067, 2009.
  [Bibtex]

  @article ISI:000264683200010,
  Author = Machala, Libor and Zboril, Radek and Sharma, Virender K. and Filip, Jan
     and Jancik, Dalibor and Homonnay, Zoltan,
  Title = Transformation of Solid Potassium Ferrate(VI) (K(2)FeO(4)): Mechanism
     and Kinetic Effect of Air Humidity,
  Journal = EUROPEAN JOURNAL OF INORGANIC CHEMISTRY,
  Year = 2009,
  Number = 8,
  Pages = 1060-1067,
  Month = MAR,
  Abstract = The kinetics of solid-state transformation (aging) of potassium
     ferrate(VI) (K(2)FeO(4)) under various air-humidity conditions (55-95\%
     relative humidity) at room temperature were studied by in-situ Mossbauer
     spectroscopy. The kinetic data showed a significant increase in the
     decomposition rate with increasing air humidity. The decomposition
     kinetics is very unusual with two almost linear decay steps. The first
     slow decay was observable at rather lower humidity levels (55-70\%)
     probably due to the formation of the narrow compact layer of
     nanoparticulate Fe(OH)(3) reaction product. This layer limits the access
     of both H(2)O and CO(2) participating in the reaction as the gaseous
     reactants. The second decay with much faster rate showed a nearly
     positive linear relationship with the humidity. The identification and
     characterization of the final products of aging were conducted by using
     X-ray diffraction (XRD), variable-temperature and in-field Mossbauer
     spectroscopy, magnetic measurements, thermogravimetry (TG) and
     differential scanning calorimetry (DSC), and scanning electron
     microscopy (SEM) techniques. The reaction mechanism, assuming formation
     of KHCO(3) and Fe(OH)(3) in the molar ratio of 2:1 per 1 mol of solid
     K(2)FeO(4) was suggested. The SEM images revealed the formation of large
     KHCO(3) crystallites whose surface was covered by ultrasmall X-ray
     amorphous iron(III) hydroxide nanoparticles in a high degree of
     agglomeration. The obtained results of aging under humid conditions are
     important for the possible storage of K(2)FeO(4) and thus for its
     environmental and industrial applications. ((C) Wiley-VCH Verlag GmbH \&
     Co. KGaA, 69451 Weinheim, Germany, 2009),
  DOI = 10.1002/ejic.200801068,
  ISSN = 1434-1948,
  Unique-ID = ISI:000264683200010,
  

2008

• L. Machala, R. Zboril, V. K. Sharma, and Z. Homonnay, “Decomposition of Potassium Ferrate(VI) (K(2)FeO(4)) and Potassium
  Ferrate(III) (KFeO(2)): In-situ Mossbauer Spectroscopy Approach,” in MOSSBAUER SPECTROSCOPY IN MATERIALS SCIENCE 2008, 2008, pp. 114-121.
  [Bibtex]

  @inproceedings ISI:000262290200015,
  Author = Machala, Libor and Zboril, Radek and Sharma, Virender K. and Homonnay,
     Zoltan,
  Editor = Mashlan, M and Zboril, R,
  Title = Decomposition of Potassium Ferrate(VI) (K(2)FeO(4)) and Potassium
     Ferrate(III) (KFeO(2)): In-situ Mossbauer Spectroscopy Approach,
  Booktitle = MOSSBAUER SPECTROSCOPY IN MATERIALS SCIENCE 2008,
  Series = AIP Conference Proceedings,
  Year = 2008,
  Volume = 1070,
  Pages = 114-121,
  Note = International Conference on Mossbauer Spectroscopy in Materials Science,
     Hlohovec, CZECH REPUBLIC, JUN 16-20, 2008,
  Abstract = Mossbauer spectroscopy was shown to be very useful technique studying
     the mechanism of thermal decomposition or aging processes of the most
     known ferrate(VI), K(2)FeO(4). In-situ Mossbauer spectroscopy approach
     was used to monitor the phase composition during the studied processes.
     The experimental set-up was designed to perform in-situ measurements at
     high temperatures and at different air humid conditions at room
     temperature. The potassium ferrate(III), KFeO(2) was demonstrated to be
     the primary product of thermal decomposition of K(2)FeO(4). The KFeO(2)
     was unstable in a humid air at room temperature and reacted with
     components of air, H(2)O and CO(2) to give Fe(2)O(3) nanoparticles and
     KHCO(3). The aging kinetics of K(2)FeO(4) and KFeO(2) under humid air
     were significantly dependent on the relative air humidity.,
  ISSN = 0094-243X,
  ISBN = 978-0-7354-0601-8,
  Unique-ID = ISI:000262290200015,
  

2007

• P. Kopel, K. Dolezal, L. Machala, and V. Langer, “Synthesis, characterization and screening of biological activity of
  Zn(II), Fe(II) and Mn(II) complexes with trithiocyanuric acid,” POLYHEDRON, vol. 26, iss. 8, pp. 1583-1589, 2007.
  [Bibtex]

  @article ISI:000246744600004,
  Author = Kopel, Pavel and Dolezal, Karel and Machala, Libor and Langer, Vratislav,
  Title = Synthesis, characterization and screening of biological activity of
     Zn(II), Fe(II) and Mn(II) complexes with trithiocyanuric acid,
  Journal = POLYHEDRON,
  Year = 2007,
  Volume = 26,
  Number = 8,
  Pages = 1583-1589,
  Month = MAY 21,
  Abstract = New Zn(II), Fe(II) and Mn(II) complexes with a combination of
     nitrogen-donor ligands and trithiocyanuric acid (ttcH(3)) were prepared
     and characterized by elemental analysis, IR and UV-Vis spectroscopies.
     The antitumor activity of the prepared complexes, together with already
     known Ni(II) species, were assayed in vitro against G-361 (human
     malignant melanoma), HOS (human osteogenic sarcoma), K-562 (human
     chronic myelogenous leukaemia) and MCF-7 (human breast adenocarcinoma)
     tumor cell lines. The IC50 values of the Fe(II) and Mn(II) compounds
     turned out to be lower than those of cisplatin and oxaliplatin. The
     antimicrobial activities were evaluated by MIC against bacteria
     (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and
     Enterococcus faecalis). The molecular structure of [Zn(taa)(ttcH)]
     center dot H2O (taa = tris(2-aminoethyl)amine) was determined by X-ray
     diffraction. The central atom is pentacoordinated by four N atoms of taa
     and one N atom of the ttcH dianion. (C) 2006 Elsevier Ltd. All rights
     reserved.,
  DOI = 10.1016/j.poly.2006.11.022,
  ISSN = 0277-5387,
  Unique-ID = ISI:000246744600004,
  

• L. Machala, R. Zboril, and A. Gedanken, “Amorphous iron(III) Oxide – A review,” JOURNAL OF PHYSICAL CHEMISTRY B, vol. 111, iss. 16, pp. 4003-4018, 2007.
  [Bibtex]

  @article ISI:000245797700002,
  Author = Machala, Libor and Zboril, Radek and Gedanken, Aharon,
  Title = Amorphous iron(III) Oxide - A review,
  Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
  Year = 2007,
  Volume = 111,
  Number = 16,
  Pages = 4003-4018,
  Month = APR 26,
  Abstract = The syntheses of amorphous Fe2O3 nanoparticles of varying size and
     morphology, their magnetic properties, crystallization mechanism, and
     applications are reviewed herein. The synthetic routes are classified
     according to the nature of the sample (powders, nanocomposites, films,
     coated particles). The contributions of various experimental techniques
     to the characterization of an amorphous Fe2O3 phase are considered in
     this review, including some key experimental markers, allowing its
     distinction from nanocrystalline ``X-ray amorphous'' polymorphs
     (maghemite, hematite). We discuss the thermally induced crystallization
     mechanisms depending on transformation temperature, atmosphere, and the
     size of the amorphous particles that predetermine the structure of the
     primarily formed crystalline polymorph. The controversial description of
     the magnetic behavior, including an interpretation of the
     low-temperature and in-field Mossbauer spectra, is analyzed.,
  DOI = 10.1021/jp064992s,
  ISSN = 1520-6106,
  Unique-ID = ISI:000245797700002,
  

• L. Machala, R. Zboril, V. K. Sharma, J. Filip, O. Schneeweiss, and Z. Homonnay, “Mossbauer characterization and in situ monitoring of thermal
  decomposition of potassium ferrate(VI), K(2)FeO(4) in static air
  conditions,” JOURNAL OF PHYSICAL CHEMISTRY B, vol. 111, iss. 16, pp. 4280-4286, 2007.
  [Bibtex]

  @article ISI:000245797700035,
  Author = Machala, Libor and Zboril, Radek and Sharma, Virender K. and Filip, Jan
     and Schneeweiss, Oldrich and Homonnay, Zoltan,
  Title = Mossbauer characterization and in situ monitoring of thermal
     decomposition of potassium ferrate(VI), K(2)FeO(4) in static air
     conditions,
  Journal = JOURNAL OF PHYSICAL CHEMISTRY B,
  Year = 2007,
  Volume = 111,
  Number = 16,
  Pages = 4280-4286,
  Month = APR 26,
  Abstract = Solid orthorhombic crystals of potassium ferrate(VI) (K(2)FeO(4)) of a
     high-chemical purity (> 99.0\%) were characterized by low-temperature
     (1.5-5 K), high-temperature (463-863 K), and in-field (1.5 K/3 T)
     Mossbauer spectroscopy. Potassium ferrate(VI) reveals a Neel magnetic
     transition temperature (T(N)) of similar to 3.8 K and a saturation
     hyperfine magnetic field of 13.8 T at 1.5 K. Spectral line intensities
     recorded below T(N) in an external magnetic field of 3 T manifest a
     perfect antiferromagnetic ordering. For the in situ monitoring of the
     thermal behavior of K(2)FeO(4), high-temperature Mossbauer data were
     combined with those obtained from thermogravimetry, differential
     scanning calorimetry, and variable-temperature X-ray diffraction
     measurements. Such in situ approach allowed the identification of the
     reaction products and intermediates and yielded the first experimental
     evidence for the participation of CO(2) in the decomposition process. As
     the primary conversion products, KFeO(2) and two potassium oxides in
     equivalent molar ratio, KO(2) and K(2)O, were suggested. However, the
     KO(2) phase is detectable with difficulty as it reacts very quickly with
     CO(2) from air resulting in the formation of K(2)CO(3). The presented
     decomposition model is consistent with thermogravimetric data giving the
     mass loss of 8.0\%, which corresponds to the participation of (1)/(6)
     mol of CO(2) and liberation of (3)/(4) mol of O(2) per 1 mol of
     K(2)FeO(4) (K(2)FeO(4) + (1)/(6)CO(2) -> KFeO(2) + (1)/(3)K(2)O +
     (1)/(6)K(2)CO(3) + (3)/(4)O(2)). An explanation of the multistage
     reaction mechanism has an important practical impact for the
     optimization of the solid-state synthesis of potassium ferrate(VI).,
  DOI = 10.1021/jp068272x,
  ISSN = 1520-6106,
  Unique-ID = ISI:000245797700035,
  

• M. Dobes, L. Machala, and J. Mikes, “Iterative image restoration and the stopping criteria,” in WMSCI 2007: 11TH WORLD MULTI-CONFERENCE ON SYSTEMICS, CYBERNETICS AND
  INFORMATICS, VOL II, PROCEEDINGS, 2007, pp. 192-195.
  [Bibtex]

  @inproceedings ISI:000254642700039,
  Author = Dobes, Michal and Machala, Libor and Mikes, Josef,
  Editor = Callaos, N and Lesso, W and Zinn, CD and Goriachkin, O,
  Title = Iterative image restoration and the stopping criteria,
  Booktitle = WMSCI 2007: 11TH WORLD MULTI-CONFERENCE ON SYSTEMICS, CYBERNETICS AND
     INFORMATICS, VOL II, PROCEEDINGS,
  Year = 2007,
  Pages = 192-195,
  Note = 11th World Multi-Conference on Systemics, Cybernetics and
     Informatics/13th International Conference on Information Systems
     Analysis and Synthesis, Orlando, FL, JUL 08-11, 2007,
  Organization = Int Inst Informat \& System,
  Abstract = Digital images can be negatively influenced by several aspects, mostly
     by camera movement, unfocussed lenses, and noise from the camera sensor.
     The reconstruction can be done by several reconstruction methods. The
     methods can be non-iterative such as Wiener reconstruction. The Wiener
     reconstruction is effective and fast for the most of ordinary images.
     Unfortunately, some artifacts are visible after the reconstruction. From
     the iterative methods, the Lucy-Richardson (LR) or blind deconvolution
     are sometimes used. Iterative algorithms are slower but the results can
     be usually better. The problem with iterative methods is that the number
     of iterations needed in order to achieve the image of adequate quality
     is not known ahead. Our experiments show how to look for appropriate
     stopping criteria, and that in case of the LR deconvolution it is
     possible to find such criteria. The original non-degraded image was not
     available. The considerations were based on judging of 100 images. The
     experiments revealed that the restored images were mostly of good
     quality.,
  ISBN = 978-1-934272-16-9,
  Unique-ID = ISI:000254642700039,
  

2006

• L. Machala, R. Zboril, V. K. Sharma, J. Filip, and O. Schneeweiss, “New view on thermal behavior of K(2)FeO(4) in static air,” ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, vol. 232, pp. 42-ENVR, 2006.
  [Bibtex]

  @article ISI:000207781604643,
  Author = Machala, Libor and Zboril, Radek and Sharma, Virender K. and Filip, Jan
     and Schneeweiss, Oldrich,
  Title = New view on thermal behavior of K(2)FeO(4) in static air,
  Journal = ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY,
  Year = 2006,
  Volume = 232,
  Pages = 42-ENVR,
  Month = SEP 10,
  ISSN = 0065-7727,
  Unique-ID = ISI:000207781604643,
  

• M. Hermanek, R. Zboril, M. Mashlan, L. Machala, and O. Schneeweiss, “Thermal behaviour of iron(II) oxalate dihydrate in the atmosphere of its
  conversion gases,” JOURNAL OF MATERIALS CHEMISTRY, vol. 16, iss. 13, pp. 1273-1280, 2006.
  [Bibtex]

  @article ISI:000236115100009,
  Author = Hermanek, M and Zboril, R and Mashlan, M and Machala, L and Schneeweiss,
     O,
  Title = Thermal behaviour of iron(II) oxalate dihydrate in the atmosphere of its
     conversion gases,
  Journal = JOURNAL OF MATERIALS CHEMISTRY,
  Year = 2006,
  Volume = 16,
  Number = 13,
  Pages = 1273-1280,
  Abstract = Using a device for thermogravimetric analysis, a dynamic study of
     thermally induced solid-state transformations of FeC(2)O(4)(.)2H(2)O in
     the atmosphere allowing full participation of gaseous products (CO, CO2,
     H2O) in the reaction system was carried out. Solid phases formed at
     various temperatures between 25 and 640 degrees C were identified and
     characterized using Fe-57 Mossbauer spectroscopy, TG and XRD. Up to 230
     degrees C, evolution of two molecules of the water of crystallization
     takes place. Superparamagnetic nanoparticles of magnetite (Fe3O4) are
     formed as the primary product of the decomposition of FeC2O4, together
     with gaseous CO and CO2. In the next stage above 380 degrees C, the
     crystallization of magnetite is accompanied by a reduction of the
     remaining ferrous oxalate to iron carbide (Fe3C) by carbon monoxide.
     Thermally induced conversion of iron carbide into alpha-Fe and carbon is
     expected between 400 and 535 degrees C as the major chemical process. In
     the last reaction step, above 535 degrees C, magnetite is reduced to
     wustite (FeO) by carbon monoxide evolved at lower temperatures. On the
     grounds of quantitative Mossbauer data possible competitive reactions
     are discussed and a temperature dependent reaction model is suggested.,
  DOI = 10.1039/b514565a,
  ISSN = 0959-9428,
  Unique-ID = ISI:000236115100009,
  

2005

• R. Zboril, L. Machala, M. Mashlan, and M. Hermanek, “Nanocrystalline iron(III) oxides formed under dynamic heating of ferrous
  oxalate dihydrate in air,” in Industrial Applications of the Mossbauer Effect, 2005, pp. 257-262.
  [Bibtex]

  @inproceedings ISI:000229434000039,
  Author = Zboril, R and Machala, L and Mashlan, M and Hermanek, M,
  Editor = Gracia, M and Marco, JF and Plazaola, F,
  Title = Nanocrystalline iron(III) oxides formed under dynamic heating of ferrous
     oxalate dihydrate in air,
  Booktitle = Industrial Applications of the Mossbauer Effect,
  Series = AIP CONFERENCE PROCEEDINGS,
  Year = 2005,
  Volume = 765,
  Pages = 257-262,
  Note = International Symposium on the Industrial Applications of the Mossbauer
     Effect, Madrid, SPAIN, OCT 04-08, 2004,
  Organization = Spansh Sci Council,
  Abstract = A dynamic study of the thermal decomposition of FeC2O4 center dot 2H(2)O
     has been carried out in air in the range of 25-500 degrees C with a
     heating rate of 5 degrees C/min using the conventional methods of
     thermal analysis including TG and DSC. The phase composition at
     different calcination temperatures was determined from Fe-57 Mossbauer
     spectra. It was found that the primary dehydration and liberation of
     carbon oxides from the oxalate structure is followed by a direct
     oxidation of Fe(II) to nanocrystalline Fe2O3 with a large surface area
     of about 250 m(2)/g. Such nanopowder is comprised of nanocrystalline
     particles of gamma- and alpha-Fe2O3 as proved by XRD, low temperature
     Mossbauer spectroscopy and HRTEM analysis. In contradiction with the
     literature assumption, no traces of magnetite (Fe3O4) have been
     identified during the oxidative decomposition in air. The simultaneous
     formation of both gamma- and alpha-Fe2O3 polymorphs at low temperatures
     is followed by an isochemical structural change of maghemite to
     hematite. The comparison of Mossbauer spectra taken at different
     temperatures proves clearly that maghemite appears in samples only as
     superparamagnetic particles at room temperature (RT), while all sextet
     components in RT Mossbauer spectra can be assigned to hematite particles
     with varying size distributions.,
  ISSN = 0094-243X,
  ISBN = 0-7354-0250-7,
  Unique-ID = ISI:000229434000039,
  

• J. Pospisil, P. Jakubik, and L. Machala, “Light-reflection random-target method for measurement of the modulation
  transfer function of a digital video-camera,” OPTIK, vol. 116, iss. 12, pp. 573-585, 2005.
  [Bibtex]

  @article ISI:000233875000005,
  Author = Pospisil, J and Jakubik, P and Machala, L,
  Title = Light-reflection random-target method for measurement of the modulation
     transfer function of a digital video-camera,
  Journal = OPTIK,
  Year = 2005,
  Volume = 116,
  Number = 12,
  Pages = 573-585,
  Abstract = This article reports the suggestion, realization and verification of the
     newly developed measuring means of the noiseless and locally
     shift-invariant modulation transfer function (MTF) of a digital video
     camera in a usual incoherent visible region of optical intensity,
     especially of its combined imaging, detection, sampling and digitizing
     steps which are influenced by the additive and spatially discrete
     photodetector, aliasing and quantization noises. Such means relates to
     the still camera automatic working regime and static two-dimensional
     spatially continuous light-reflection random target of white-noise
     property. The introduced theoretical reason for such a random-target
     method is also performed under exploitation of the proposed simulation
     model of the linear optical intensity response and possibility to
     express the resultant MTF by a normalized and smoothed rate of the
     ascertainable output and input power spectral densities. The
     random-target and resultant image-data were obtained and processed by
     means of a processing and evaluational PC with computation programs
     developed on the basis of MATLAB 6.5. The present examples of results
     and other obtained results of the performed measurements demonstrate the
     sufficient repeatability and acceptability of the described method for
     comparative evaluations of the performance of digital video cameras
     under various conditions. (c) 2005 Elsevier GmbH. All rights reserved.,
  DOI = 10.1016/j.ijleo.2005.04.005,
  ISSN = 0030-4026,
  Unique-ID = ISI:000233875000005,
  

2004

• R. Zboril, L. Machala, M. Mashlan, and V. Sharma, “Iron(III) oxide nanoparticles in the thermally induced oxidative
  decomposition of Prussian Blue, Fe(4)[Fe(CN)(6)](3),” CRYSTAL GROWTH & DESIGN, vol. 4, iss. 6, pp. 1317-1325, 2004.
  [Bibtex]

  @article ISI:000224983100034,
  Author = Zboril, R and Machala, L and Mashlan, M and Sharma, V,
  Title = Iron(III) oxide nanoparticles in the thermally induced oxidative
     decomposition of Prussian Blue, Fe(4)[Fe(CN)(6)](3),
  Journal = CRYSTAL GROWTH \& DESIGN,
  Year = 2004,
  Volume = 4,
  Number = 6,
  Pages = 1317-1325,
  Month = NOV-DEC,
  Abstract = The thermally induced decomposition of Prussian Blue,
     Fe(4)[Fe(CN)(6)](3) (PB), was studied in air at 250 and 350 C.
     Amorphous Fe(2)O(3) nanoparticles, cubic bixbyite beta- and cubic spinel
     gamma-Fe(2)O(3) (maghemite) polymorphs, have been identified as the
     products of the decomposition under different reaction conditions.
     (57)Fe Mossbauer spectroscopy, XRD, AFM, TEM, quasielastic light
     scattering method (QELS) of particle size analysis, BET surface area,
     and magnetization measurements were used to understand the influence of
     the PB particle size and oxidation conditions on the decomposition
     mechanism at 250 and 350 C. At a minimum decomposition temperature of
     250 degreesC, amorphous Fe(2)O(3) nanoparticles were formed with the
     size ranging from 1 to 4 nm and large surface area of 400-200 m(2)/g in
     dependence on the PB particle size. Such small amorphous Fe(2)O(3)
     nanoparticles were obtained by the solid-state route for the first time.
     At 350 degreesC, cubic beta-Fe(2)O(3) and gamma-Fe(2)O(3) polymorphs
     were identified and their contents were found to be strongly dependent
     on the initial PB particle size and oxidation-diffusion conditions.
     Generally, the higher relative content of gamma-Fe(2)O(3) was obtained
     for larger PB particles and in air-limited conditions.,
  DOI = 10.1021/cg049748+,
  ISSN = 1528-7483,
  Unique-ID = ISI:000224983100034,
  

• R. Zboril, M. Mashlan, L. Machala, J. Walla, K. Barcova, and P. Martinec, “Characterization and thermal behaviour of garnets from almandine-pyrope
  series at 1200 degrees C,” HYPERFINE INTERACTIONS, vol. 156, iss. 1, pp. 403-410, 2004.
  [Bibtex]

  @article ISI:000224130500062,
  Author = Zboril, R and Mashlan, M and Machala, L and Walla, J and Barcova, K and
     Martinec, P,
  Title = Characterization and thermal behaviour of garnets from almandine-pyrope
     series at 1200 degrees C,
  Journal = HYPERFINE INTERACTIONS,
  Year = 2004,
  Volume = 156,
  Number = 1,
  Pages = 403-410,
  Month = JUN-SEP,
  Note = 27th International Conference on the Applications of the Mossbauer
     Effect, Muscat, OMAN, SEP 21-25, 2003,
  Abstract = The natural garnets from almandine (Fe3Al2Si3O12) -pyrope (Mg3Al2Si3O12)
     series with the iron to magnesium atomic ratio ranging from 0.2 to 1
     were characterised and their thermal behaviour at 1200degreesC studied
     by Fe-57 Mossbauer spectroscopy, X-ray powder diffraction, X-ray
     fluorescence, DTA, TG and electron microprobe analysis. The pyrope-type
     samples with a dominant magnesium content at position 24c in the cubic
     garnet structure undergo oxidative decomposition at 1200degreesC
     resulting in the formation of the paramagnetic spinel Mg(Al, Fe)(2)O-4
     structure with a low iron content, enstatite (Mg, Fe) SiO3 and anorthite
     CaAl2Si2O8 as the host compound for calcium. Contrary to pyropes, the
     iron-rich garnets exhibit complete oxidation at 1200degreesC conforming
     to the formation of magnetically ordered nanocrystalline gamma-Fe2O3 or
     Mg(Fe, Al)(2)O-4 spinels depending on the initial chemical composition
     of the garnets. In the reaction products of iron-rich garnets,
     cordierite (Mg2Al4Si5O18) and anorthite were identified as non-ferrous
     phases.,
  DOI = 10.1023/B:HYPE.0000043260.24239.48,
  ISSN = 0304-3843,
  Unique-ID = ISI:000224130500062,
  

• M. Mashlan, R. Zboril, L. Machala, M. Vujtek, J. Walla, and K. Nomura, “Mossbauer spectroscopy in study of thermally induced crystallization of
  amorphous Fe(2)O(3) nanoparticles,” in ISMANAM 2003: METASTABLE, MECHANICALLY ALLOYED AND NANOCRYSTALLINE
  MATERIALS, 2004, pp. 641-647.
  [Bibtex]

  @inproceedings ISI:000223641200101,
  Author = Mashlan, M and Zboril, R and Machala, L and Vujtek, M and Walla, J and
     Nomura, K,
  Editor = Kiminami, CS and Bolfarini, C and BottaF, WJ,
  Title = Mossbauer spectroscopy in study of thermally induced crystallization of
     amorphous Fe(2)O(3) nanoparticles,
  Booktitle = ISMANAM 2003: METASTABLE, MECHANICALLY ALLOYED AND NANOCRYSTALLINE
     MATERIALS,
  Series = JOURNAL OF METASTABLE AND NANOCRYSTALLINE MATERIALS SERIES,
  Year = 2004,
  Volume = 20-21,
  Pages = 641-647,
  Note = 10th International Symposium on Metastable, Mechanically Alloyed and
     Nanocrystalline Materials (ISMANAM 2003), Foz do Iguacu, BRAZIL, AUG
     24-28, 2003,
  Abstract = (57)Fe Mossbauer spectroscopy is demonstrated as an effective tool in
     the identification, magnetic and structural characterization of
     iron(III) oxides formed by thermally induced oxidative decomposition of
     FeC(2)O(4).2H(2)O and by the secondary crystallization of amorphous
     Fe(2)O(3) nanopowder. AFM measurements revealed that the primary
     amorphous nanoparticles are between 1 and 3 nm, in accordance with the
     large surface area of 250 m(2)/g as determined by BET analysis. The
     temperature depended Mossbauer measurements of amorphous Fe(2)O(3)
     showed the magnetic transition temperature lower than 70 K with the
     sharp evolution of the spectral lines between 53 and 76 K as typical for
     ultrafine and strongly interacted particles. As the primary
     crystallization product at low temperatures, gamma-Fe(2)O(3) (maghemite)
     was identified by XRD. The broad distribution of magnetic fields in
     Mossbauer spectra illustrates the broad size distribution of maghemite
     nanoparticles. The thermally stable alpha-Fe(2)O(3) (hematite) can be
     produced by the direct crystallization of amorphous phase at higher
     temperatures or by the structural transformation of the primarily formed
     maghemite at lower temperatures. Particles of hematite formed at
     200degreesC reveal the Morin transition temperature suppressed below 20
     K corresponding to the size about 20 nm.,
  ISSN = 1422-6375,
  ISBN = 0-87849-944-X,
  Unique-ID = ISI:000223641200101,
  

• M. Dobes, L. Machala, P. Tichavsky, and J. Pospisil, “Human eye iris recognition using the mutual information,” OPTIK, vol. 115, iss. 9, pp. 399-404, 2004.
  [Bibtex]

  @article ISI:000225790200003,
  Author = Dobes, M and Machala, L and Tichavsky, P and Pospisil, J,
  Title = Human eye iris recognition using the mutual information,
  Journal = OPTIK,
  Year = 2004,
  Volume = 115,
  Number = 9,
  Pages = 399-404,
  Abstract = This article presents the new biometric electro-optical measuring method
     supported by PC for identification of a person by its eye iris image
     recognition. The aim of this approach is to show the ability of mutual
     information to such recognition. Couples of the comparative human iris
     images were geometrically aligned by maximization of their mutual
     information and subsequently recognized. The mutual information was
     estimated using the efficient algorithm proposed by G. A. Darbellay and
     I.Vajda. The decision whether two compared iris images belong to the
     same eye depends on the chosen threshold of the mutual information. Only
     a simple preprocessing of the iris images is needed to acquire their
     characteristic geometric parameters before the recognition is performed.
     The investigations carried out showed the correct (successful) personal
     identification better than 99\%.,
  DOI = 10.1078/0030-4026-00388,
  ISSN = 0030-4026,
  Unique-ID = ISI:000225790200003,
  

• R. Zboril, L. Machala, M. Mashlan, M. Hermanek, M. Miglierini, and A. Fojtik, “Structural, magnetic and size transformations induced by isothermal
  treatment of ferrous oxalate dihydrate in static air conditions,” in SECOND SEEHEIM CONFERENCE ON MAGNETISM, PROCEEDINGS, 2004, pp. 3583-3588.
  [Bibtex]

  @inproceedings ISI:000227060600080,
  Author = Zboril, R and Machala, L and Mashlan, M and Hermanek, M and Miglierini,
     M and Fojtik, A,
  Editor = Ghafari, M and Enz, T and Hahn, H,
  Title = Structural, magnetic and size transformations induced by isothermal
     treatment of ferrous oxalate dihydrate in static air conditions,
  Booktitle = SECOND SEEHEIM CONFERENCE ON MAGNETISM, PROCEEDINGS,
  Year = 2004,
  Pages = 3583-3588,
  Note = 2nd Seeheim Conference on Magnetism (SCM2004), Seeheim, GERMANY, JUN
     27-JUL 01, 2004,
  Organization = Deutsch Forsch Gemeinsch; Forsch Zentrum Karlsruhe; Darmstadt Univ
     Technol,
  Abstract = Thermal decomposition of the FeC2O4.2H(2)O powder has been studied
     isothermally in static air conditions at minimum decomposition
     temperature of 180 degreesC using Fe-57 Mossbauer spectroscopy, XRD,
     HRTEM, AFM and BET surface area measurements. Dehydration and liberation
     of carbon oxides from powdered sample is accompanied by direct oxidation
     of Fe(II) to nanocrystalline Fe2O3 without any indications of the
     stabilization of the magnetite (Fe3O4) phase. Decomposition process is
     completed after two hours and as-prepared nanopowder (3-5 nm), with a
     large surface area of about 250 m(2)/g, is comprised of ultrafine
     superparamagnetic particles of gamma-Fe2O3 (maghemite) and alpha-Fe2O3
     (hematite) as proved by low temperature Mossbauer spectroscopy, XRD and
     HRTEM analysis. The simultaneous formation of both polymorphs is
     probably related with the non-equivalent diffusion conditions on the
     surface and in the bulk of oxalate particles. With increasing time, the
     particle size induced phase transformation of maghemite to hematite has
     been observed by AFM and XRD. Mossbauer spectra demonstrate that
     maghemite particles are formed only in superparamagnetic state
     (doublet), while magnetic components (sextet) in room temperature
     spectra can be assigned exclusively to hematite particles with size
     distribution produced by gradual crystallization of primary
     superparamagnetic nanoparticles of the same structure as well as by the
     phase transition of maghemite phase. (C) 2004 WILEYNCH Verlag GmbH \&
     Co. KGaA, Weinheim.,
  DOI = 10.1002/pssc.200405511,
  ISBN = 3-527-40577-1,
  Unique-ID = ISI:000227060600080,
  

2003

• R. Zboril, M. Mashlan, L. Machala, and P. Bezdicka, “Iron(III) oxides formed during thermal conversion of rhombohedral
  iron(III) sulfate,” in MATERIAL RESEARCH IN ATOMIC SCALE BY MOSSBAUER SPECTROSCOPY, 2003, pp. 21-30.
  [Bibtex]

  @inproceedings ISI:000183172700003,
  Author = Zboril, R and Mashlan, M and Machala, L and Bezdicka, P,
  Editor = Mashlan, M and Miglierini, M and Schaaf, P,
  Title = Iron(III) oxides formed during thermal conversion of rhombohedral
     iron(III) sulfate,
  Booktitle = MATERIAL RESEARCH IN ATOMIC SCALE BY MOSSBAUER SPECTROSCOPY,
  Series = NATO Science Series II-Mathematics Physics and Chemistry,
  Year = 2003,
  Volume = 94,
  Pages = 21-30,
  Note = Conference of the NATO Advanced Research Workshop on Material Research
     in Atomic Scale by Mossbauer Spectroscopy, SMOLENICE, SLOVAKIA, JUN
     01-06, 2002,
  Organization = NATO,
  Abstract = The mechanism of thermal decomposition of rhombohedral iron(Ill) sulfate
     in air depends significantly on the conditions for diffusion of SO(3)
     (temperature, thickness of the powdered layer, particle size). The
     influence of particle size on the reaction mechanism was studied at
     600degreesC using (57)Fe Mossbauer spectroscopy and XRD. Corundum-type
     alpha-Fe(2)O(3) bixbyite-type beta-Fe(2)O(3) and orthorhombic
     epsilon-Fe(2)O(3) were identified as solid conversion products. Time
     dependence of the relative contents of individual polymorphs
     (x-Fe(2)O(3)/SigmaFe(2)O(3)) is a suitable means for monitoring the
     mechanism of their formation and thermal transformation during the
     reaction process. The quantitative Mossbauer data obtained from the
     corresponding spectral areas demonstrate that different transformations
     occur in the surface, layer and in the bulk of sulfate particles.
     Particles of beta-Fe(2)O(3) formed after loosening Of SO(3) from the
     surface layer of sulfate particles are relatively stable at 600degreesC
     as documented by the very slow structural change to hematite. The
     formation of complicated epsilon-Fe(2)O(3) structure is probably related
     with the slow diffusion Of SO(3) from the bulk of sulfate particles. The
     isochemical transformation of epsilon-Fe(2)O(3) to hematite occurs more
     quickly due to its lower thermal stability in comparison with
     beta-Fe(2)O(3).,
  ISSN = 1568-2609,
  ISBN = 1-4020-1196-2,
  Unique-ID = ISI:000183172700003,
  

2001

• L. Machala and J. Pospisil, “Alternatives of the statistical evaluation of the human iris structure,” in 12TH CZECH-SLOVAK-POLISH OPTICAL CONFERENCE ON WAVE AND QUANTUM ASPECTS
  OF CONTEMPORARY OPTICS, 2001, pp. 385-393.
  [Bibtex]

  @inproceedings ISI:000169323500056,
  Author = Machala, L and Pospisil, J,
  Editor = Perina, J and Hrabovsky, M and Krepelka, J,
  Title = Alternatives of the statistical evaluation of the human iris structure,
  Booktitle = 12TH CZECH-SLOVAK-POLISH OPTICAL CONFERENCE ON WAVE AND QUANTUM ASPECTS
     OF CONTEMPORARY OPTICS,
  Series = PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS
     (SPIE),
  Year = 2001,
  Volume = 4356,
  Pages = 385-393,
  Note = 12th Czech-Slovak-Polish Optical Conference on Wave and Quantum Aspects
     of Contemporary Optics, VELKE LOSINY, CZECH REPUBLIC, SEP 12-15, 2000,
  Organization = SPIE Czech \& Slovak Chapter; Acad Sci Czech Republ, Palacky Univ \&
     Inst Phys; Palacky Univ, Dept Opt,
  Abstract = This article presents the proposal of two new methods (alternatives) of
     the statistical and computer evaluations of the iris structure of a
     human eye in view of person identification, based partly on the
     correlation analysis and partly on the median binary code of
     commensurable regions of digitized iris images. The results of the
     measurement by the mentioned methods are presented, compared and
     evaluated subsequently.,
  DOI = 10.1117/12.417859,
  ISSN = 0277-786X,
  ISBN = 0-8194-4047-7,
  Unique-ID = ISI:000169323500056,
  

• L. Machala and J. Pospisil, “Proposal and verification of two methods for evaluation of the human
  iris video-camera images,” OPTIK, vol. 112, iss. 8, pp. 335-340, 2001.
  [Bibtex]

  @article ISI:000172011800003,
  Author = Machala, L and Pospisil, J,
  Title = Proposal and verification of two methods for evaluation of the human
     iris video-camera images,
  Journal = OPTIK,
  Year = 2001,
  Volume = 112,
  Number = 8,
  Pages = 335-340,
  Abstract = This article presents the proposal of two new methods of the statistical
     and computer evaluation of the iris structure of a human eye in view of
     identification of a person, based partly on the correlation analysis and
     partly on the direct comparison of commensurable regions of digitized
     iris images. The results of the measurements by the mentioned methods
     are presented, compared and evaluated subsequently.,
  DOI = 10.1078/0030-4026-00066,
  ISSN = 0030-4026,
  Unique-ID = ISI:000172011800003,
  

1994

• L. MACHALA, “ZAPLETAL,ZDENEK + CONTEMPORARY CZECH WRITER – FROM FOLKLORE TO BOOKS,” CESKA LITERATURA, vol. 42, iss. 6, pp. 608-620, 1994.
  [Bibtex]

  @article ISI:A1994QG29300005,
  Author = MACHALA, L,
  Title = ZAPLETAL,ZDENEK + CONTEMPORARY CZECH WRITER - FROM FOLKLORE TO BOOKS,
  Journal = CESKA LITERATURA,
  Year = 1994,
  Volume = 42,
  Number = 6,
  Pages = 608-620,
  ISSN = 0009-0468,
  Unique-ID = ISI:A1994QG29300005,