Vladimír Havranek

Dr. Vladimír Havranek


Research Focus & Metrics

Academic Career Length

35Years (1992-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 February 2004 in Journal of Radioanalytical and Nuclear Chemistry
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VHVladimír Havranek
Vladimír Havranek
JKJ. Kučera
J. Kučera
ZŘZ. Řanda
Z. Řanda
VVV. Voseček
V. Voseček

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Mariapompea CutroneoMariapompea Cutroneo
Mariapompea Cutroneo
VHVladimír Havranek
Vladimír Havranek
Anna MackováAnna Macková
Anna Macková
PMPetr Malinsky
Petr Malinsky
LSLetteria Silipigni
Letteria Silipigni
LTLorenzo Torrisi
Lorenzo Torrisi
Typically, polymeric composites containing nanoparticles are realized by incorporating pre-made nanoparticles into a polymer matrix by using blending solvent or by the reduction of metal salt dispersed in the polymeric matrix. Generally, the production of pre-made Au NPs occurs in liquids with two-step processes: producing the gold nanoparticles first and then adding them to the liquid polymer. A reproducible method to synthetize Au nanoparticles (NPs) into polydimethylsiloxane (PDMS) without any external reducing or stabilizing agent is a challenge. In this paper, a single-step method is proposed to synthetize nanoparticles (NPs) and at the same time to realize reproducible porous and bulk composites using laser ablation in liquid. With this single-step process, the gold nanoparticles are therefore produced directly in the liquid polymer. The optical properties of the suspensions of AuNPs in distilled water and in the curing agent have been analyzed by the UV-VIS spectroscopy, employed in the transmission mode, and compared with those of the pure curing agent. The electrical dc conductivity of the porous PDMS/Au NPs nanocomposites has been evaluated by the I–V characteristics. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis have monitored the composition and morphology of the so-obtained composites and the size of the fabricated Au nanoparticles. Atomic force microscopy (AFM) has been used to determine the roughness of the bulk PDMS and its Au NP composites.

10 December 2021 in Coatings
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Mariapompea CutroneoMariapompea Cutroneo
Mariapompea Cutroneo
VHVladimír Havranek
Vladimír Havranek
JFJosef Flaks
Josef Flaks
PMPetr Malinsky
Petr Malinsky
LTLorenzo Torrisi
Lorenzo Torrisi
Anna MackováAnna Macková
Anna Macková
Polydimethylsiloxane (PDMS) is a silicone-elastomer that owes its large application in the field of stretchable electronics to its chemical and thermal stability, transparency, flexibility, non-toxicity, compatibility, and low cost. PDMS is a versatile material because it can be used both as an elastic substrate and, after functionalization, as an active material for the design of stretchable electronics. One possible route for the functionalization of PDMS, thus becoming an active material together with numerous metals and semiconductors, is the embedding of conductive nanomaterials. Presently, pulsed laser deposition (PLD) and laser-induced backward transfer (LIBT) are used to deposit carbon- based material on polydimethylsiloxane. In this study, we explore and compare the surface treatments, advantages, and disadvantages of both different employed techniques in different environments. The modification of the wettability, elasticity, morphology, composition, and optical characteristics of polydimethylsiloxane will be evaluated by surface techniques such as scanning electron microscopy, Rutherford backscattering spectrometry, and the sessile drop method.

10 July 2019 in Heritage
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LTLorenzo Torrisi
Lorenzo Torrisi
Valentina VenutiValentina Venuti
Valentina Venuti
Vincenza CrupiVincenza Crupi
Vincenza Crupi
LSLetteria Silipigni
Letteria Silipigni
Mariapompea CutroneoMariapompea Cutroneo
Mariapompea Cutroneo
DMDomenico Majolino
Domenico Majolino
The present work is aimed at the investigation of the ceramic bulk and pigmented glazed surfaces of ancient potteries dating back to XIX century A.D. and coming from the charming archeological site located in the Medieval Agsu town (Azerbaijan), a geographic area of special interest due to the ancient commercial routes between China, Asia Minor, and Europe. For the purpose of the study, complementary investigation tools have been exploited: non-destructive or micro-destructive investigation at elemental level by ion beam analysis (IBA) techniques, by using Rutherford Backscattering Spectrometry (RBS), Proton-Induced X-ray Emission (PIXE) spectroscopy and ion-microbeam analysis, and chemical characterization at microscopic level, by means of synchrotron radiation (SR) Fourier transform infrared (FTIR) microspectroscopy. The acquired information reveals useful for the identification of the provenance, the reconstruction of the firing technology, and finally, the identification of the pigment was used as a colorant of the glaze.

21 February 2023 in Polymers
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PMPetr Malinsky
Petr Malinsky
OROleksander Romanenko
Oleksander Romanenko
VHVladimír Havranek
Vladimír Havranek
Mariapompea CutroneoMariapompea Cutroneo
Mariapompea Cutroneo
JNJosef Novák
Josef Novák
Anna MackováAnna Macková
Anna Macková
In this study, novel flexible micro-scale humidity sensors were directly fabricated in graphene oxide (GO) and polyimide (PI) using ion beam writing without any further modifications, and then successfully tested in an atmospheric chamber. Two low fluences (3.75 × 1014 cm−2 and 5.625 × 1014 cm−2) of carbon ions with an energy of 5 MeV were used, and structural changes in the irradiated materials were expected. The shape and structure of prepared micro-sensors were studied using scanning electron microscopy (SEM). The structural and compositional changes in the irradiated area were characterized using micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Rutherford back-scattering spectroscopy (RBS), energy-dispersive X-ray spectroscopy (EDS), and elastic recoil detection analysis (ERDA) spectroscopy. The sensing performance was tested at a relative humidity (RH) ranging from 5% to 60%, where the electrical conductivity of PI varied by three orders of magnitude, and the electrical capacitance of GO varied in the order of pico-farads. In addition, the PI sensor has proven long-term sensing stability in air. We demonstrated a novel method of ion micro-beam writing to prepare flexible micro-sensors that function over a wide range of humidity and have good sensitivity and great potential for widespread applications.

10 March 2023 in Coatings
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Mariapompea CutroneoMariapompea Cutroneo
Mariapompea Cutroneo
LTLorenzo Torrisi
Lorenzo Torrisi
LSLetteria Silipigni
Letteria Silipigni
VHVladimír Havranek
Vladimír Havranek
Anna MackováAnna Macková
Anna Macková
PSPetr Slepicka
Petr Slepicka
A cyclic olefin copolymer (COC) is a thermoplastic polymer endowed with glass-like optical transparency, unique biocompatibility, low autofluorescence, good chemical stability, and excellent water vapor barriers. COC is a promising new material for optics, medical devices, nanotechnology, and microelectronics. The applicability of the COC depends on its modification through different techniques from plasma treatment to lithography. Presently, pulsed laser deposition (PLD) is employed to deposit an aluminum thin film on selected areas of the COC surface. The study of the wettability, morphology, composition, and optical characteristics of both pristine and modified COC has been evaluated by scanning electron and atomic force microscopies, the sessile drop method, and UV/ViS optical spectroscopy. The prospective recycling of the COC deposited by PLD is proposed.