Jiri Pechousek

Jiri Pechousek
Palacký University Olomouc · Department of Experimental Physics

Assoc. Prof.

About

95
Publications
28,945
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1,801
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January 2004 - December 2010
Palacký University

Publications

Publications (95)
Article
Full-text available
57Fe transmission and conversion electron Mössbauer spectroscopy as well as XRD were used to study the effect of swift heavy ion irradiation on stress-annealed FINEMET samples with a composition of Fe73.5Si13.5Nb3B9Cu1. The XRD of the samples indicated changes neither in the crystal structure nor in the texture of irradiated ribbons as compared to...
Article
The application of microwave irradiation for rapid synthesis of magnetic biochar from agricultural waste with the subsequent modification of carbon matrix by magnetic nanoparticles was performed. The magnetic biochar was characterized by 57Fe Mössbauer spectroscopy, X-ray diffraction, a low-temperature nitrogen adsorption method, and electron micro...
Article
Proportional gas counters are commonly used in the 57 Fe Mössbauer spectroscopy for their good energy resolution and insensitivity to magnetic field. However, their counting rate is usually limited by relatively long dead time. This paper demonstrates a detection performance improving technique by registration K α escape peaks coupled together with...
Article
Full-text available
Low-alloy 42CrMo4 steels were studied by 57Fe Mössbauer spectroscopy (MS), X-ray diffractometry (XRD), and Energy Dispersive X-ray Spectroscopy (EDS) measurements. The investigations were performed on metallographic samples, which were subjected to a series of successive grinding and polishing with a progressively finer grit. Conversion X-ray Mössb...
Article
We have investigated the dynamics of magnetization under a current pulse in a φ 0 - junction with a direct coupling between the magnetic moment and the superconducting current. The correspondence between the magnetization value at the end of the pulse m z * and the realization of the magnetization reversal along the easy axis of the ferromagnetic i...
Poster
Full-text available
The presented Mössbauer spectrometer setup is based on the toroidal proportional gas flow counter [1], which is able to register both conversion X-rays (6.4 keV) and low energy gamma rays (14.4 keV) commonly utilized in the 57Fe Mössbauer spectroscopy. In particular, the detector was developed for bulk sample (typically with a diameter of 20 mm) su...
Article
A new Mössbauer spectrometer based on a CompactRIO platform was developed. The CompactRIO is a modular industrial computer platform developed by the National Instruments. This device runs under “LabVIEW RT OS” -Linux-based Real-Time Operating system, which has a support of the LabVIEW programming environment. The CompactRIO has an integrated FPGA (...
Article
Full-text available
β-phase polyvinylidene fluoride (PVDF) nanogenerators along with various concentrations (0.2, 0.4, 0.6, and 0.8 wt%) of iron oxide (Fe2O3) nanoparticles were produced using the electrospinning technique. The characterization of the free- and doped-nanogenerators was examined by X-ray powder diffraction, Fourier transform infrared spectroscopy, scan...
Poster
Full-text available
In this work we present a technical design of a microreactor chamber that is compatible with the transmission Mössbauer spectroscopy (TMS). Mössbauer spectroscopy is nowadays a very common tool for material study in nanotechnology, basic research and metallurgy. However, standard transmission geometry does not enable to conduct observations under m...
Article
Full-text available
Advanced thermomechanical hot rolling is becoming a widely used technology for the production of fine-grained spring steel. Different rapid phase transformations during the inductive heat treatment of such steel causes the inhomogeneous mixture of martensitic, bainitic, and austenitic phases that affects the service properties of the steel. An impo...
Article
Full-text available
Mössbauer spectra linearity is a critical parameter for Mössbauer spectrometer accuracy determination. This paper deals with comparison of various Mössbauer spectra linearizing methods. First method uses sine velocity waveform followed by linearization process. Next method introduces additional modulation based on the velocity error signal measured...
Article
Full-text available
This study presents an investigation of thermal decomposition of ferrous oxalate dihydrate in the combined atmosphere of inert and conversion gases to find an optimal route for a simple magnetite preparation. Homogenized precursor was isothermally treated inside the stainless-steel cells at 8 equidistant temperatures ranging from 300 to 650 °C for...
Article
In this paper we present a pulse signal processing which combines the pulse amplitude and length discrimination. The introduced technique improves the signal-to-noise ratio, especially in case of low energy gamma radiation. The effectiveness of this approach is demonstrated on the discrimination of 6.3 keV X-ray and 14.4 keV gamma radiation of ⁵⁷Co...
Article
Full-text available
Main conclusion Fe uptake machinery of chloroplasts prefers to utilise Fe(III)–citrate over Fe–nicotianamine complexes. Iron uptake in chloroplasts is a process of prime importance. Although a few members of their iron transport machinery were identified, the substrate preference of the system is still unknown. Intact chloroplasts of oilseed rape (...
Article
The objective of this paper is to determine a mathematical modelling of piezoceramic disc vibration using a single degree freedom mechanical model, with estimation of its elasticity modulus. The experimental vibration displacement values of piezo ceramic disc have been achieved utilizing the swept-sine signal excitation following the peak values in...
Article
In this note we describe an application of backscattering 57Fe Mössbauer spectroscopy for determination of the austenite content in steels, where the surface analysed thickness is ∼20 µm. The method enables rapid determination of the residual austenite in the sample, i.e. within 10-20 minutes with a sufficient accuracy. Calculations using different...
Article
We report the synthesis of pristine and nickel containing iron oxide (α-Fe2O3) nanocrystallites by facile environmentally benign wet chemical process. The magnetic behaviour of the samples has been found to change progressively with nickel content. The Mössbauer spectra revealed the precipitation of secondary phase of nickel ferrite (NiFe2O4) at ∼2...
Article
Full-text available
Adsorption is one of the best methods for wastewater purification. The fact that water quality is continuously decreasing requires the development of novel, effective and cost available adsorbents. Herein, a simple procedure for the preparation of a magnetic adsorbent from agricultural waste biomass and ferrofluid has been introduced. Specifically,...
Article
This note reports the development of a new method for linearizing the Mössbauer spectra recorded with a sine drive velocity signal. Mössbauer spectra linearity is a critical parameter to determine Mössbauer spectrometer accuracy. Measuring spectra with a sine velocity axis and consecutive linearization increases the linearity of spectra in a wider...
Data
Table S1. PCR primers used for construction of PqqE mutant enzymes
Conference Paper
Full-text available
The objective of this paper is to determine energy dissipation ratio of a PEA through a digital measurement system with laser displacement sensor. The experimental vibration displacement values of PEA have been achieved utilizing the swept-sine signal excitation following the peak values in the signal response measured by the laser Doppler vibromet...
Article
Full-text available
We report an improvement of the artificial neural network (ANN) modelling of a piezoelectric actuator vibration based on the experimental data. The controlled vibrations of an actuator were obtained by utilizing the swept-sine signal excitation. The peak value in the displacement signal response was measured by a laser displacement sensor. The piez...
Article
Full-text available
PqqE is a radical S-adenosyl-l-methionine (SAM) enzyme that catalyzes the initial reaction of pyrroloquinoline quinone (PQQ) biosynthesis. PqqE belongs to the SPASM (subtilosin/PQQ/anaerobic sulfatase/mycofactocin maturating enzymes) subfamily of the radical SAM superfamily and contains multiple Fe-S clusters. To characterize the Fe-S clusters in P...
Article
Full-text available
In Fe[N(SiPh2Me)2]2 molecular magnet, an extraordinary B ≈ 92 T hyperfine field was found in the 5 K ⁵⁷Fe Mössbauer spectrum under an external magnetic field of 0.1 T. This evidences the presence of an unquenched orbital angular moment at the central iron atom. Fe[N(SiPh2Me)2]2 complex is thus shown to represent a further example of low-coordinate...
Article
Full-text available
Nowadays, piezoelectric sensors are used in many areas such as health monitoring of steel structures using thickness modes study of piezoelectric patches, in electricity storage systems for power harvesting by converting a mechanical energy into an electrical one, in monitoring a body structure of aircrafts, in the moving parts of the mechatronics...
Article
This paper reports on the development of a gamma-ray spectroscopic system for the (i) recording and (ii) processing of spectra. The utilized data read-out unit consists of a PCI digital oscilloscope, personal computer and LabVIEW™ programming environment. A pulse-height spectra of various sources were recorded with two NaI(Tl) detectors and analyze...
Article
Full-text available
Main conclusion: Fe deficiency responses in Strategy I causes a shift from the formation of partially removable hydrous ferric oxide on the root surface to the accumulation of Fe-citrate in the xylem. Iron may accumulate in various chemical forms during its uptake and assimilation in roots. The permanent and transient Fe microenvironments formed d...
Article
A magnetic photocatalytic material composed of nanoscale zero-valent iron (nZVI) homogeneously distributed over mesoporous nanocrystalline TiO2 matrix has been prepared by a multistage chemical process, including sol-gel technique, wet impregnation, and chemical reduction. X-ray powder diffraction and Raman spectroscopy were used for the structural...
Article
For the ubiquitous diazotrophic rhizobacterium Azospirillum brasilense, which has been attracting the attention of researchers worldwide for the last 35 years owing to its significant agrobiotechnological and phytostimulating potential, the data on iron acquisition and its chemical speciation in cells are scarce. In this work, for the first time fo...
Article
Full-text available
A nanocatalyst comprising ultra-small Pd/PdO nanoparticles (<5 nm) supported on maghemite was prepared by a co-precipitation protocol using inexpensive raw materials and was deployed successfully in various significant synthetic transformations, namely the Heck–Mizoroki olefination (up to 95%), the Suzuki reaction (60–95%), and the allylic oxidatio...
Article
Full-text available
A template-free solid-state synthesis of a morphologically controlled and highly organized iron(III)oxide micro–mesoporous Fenton catalyst has been engineered through a simple two-step synthetic procedure. The 3D nanoassembly of hematite nanoparticles (5–7 nm) organized into a rod/flower-like morphology shows the highest rate constant reported to d...
Article
A magnetically retrievable, efficient, and benign maghemite-Cu nanocatalyst was synthesized from inexpensive precursors and applied for CO, CN, and CS bond-formation reactions. The obtained maghemite-Cu nanocatalyst was characterized by various techniques such as XRD, X-ray photoelectron spectroscopy, field-emission gun SEM with energy-dispersive s...
Conference Paper
Full-text available
A linearity of the Mössbauer spectrometer velocity scale is evaluated. Non-contact method for measurement the mechanical displacement of the moving part in the double-loudspeaker type velocity transducer is presented. For this purposes the laser vibrometer based on Keyence LK-G5000 system has been utilized. Real displacement (μm), velocity (mm/s) a...
Article
Full-text available
Well decorated maghemite-supported ultra-fine Pd (1-3 nm) nanoparticles, prepared by a simple co-precipitation method, find application in the catalytic continuous flow hydrogenation of nitroarenes, azides, and alkenes wherein they play an important role in reduction of various functional groups on the surface of maghemite with low catalyst loading...
Article
Full-text available
Quality and performance of a detection system are the crucial parameters in all nuclear physics experiments. This system serves as a source of all signals and noises to be processed. Better performance, higher amplification and lower noises occurrence simplify subsequent signal analysis. In the field of Mössbauer spectroscopy, the spectrum quality...
Article
Core–shell nanoparticles (CSNs) are a class of nanostructured materials that have recently received increased attention owing to their interesting properties and broad range of applications in catalysis, biology, materials chemistry and sensors. By rationally tuning the cores as well as the shells of such materials, a range of core–shell nanopartic...
Article
Methylobacterium extorquens AM1 is an aerobic facultative methylotroph known to secrete pyrroloquinoline quinone (PQQ), a cofactor of a number of bacterial dehydrogenases, into the culture medium. To elucidate the molecular mechanism of PQQ biosynthesis, we are focusing on PqqE which is believed to be the enzyme catalyzing the first reaction of the...
Article
Full-text available
Nickel ferrite NiFe2O4 is a typical soft magnetic ferrite with high electrical resistivity used as high frequency magnetic material. Neodymium (Nd3+) doped NiFe2O4 materials were fabricated using solid state reaction. The properties of the obtained material were investigated by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Fourier-Tr...
Article
Full-text available
In this study, dielectric properties within 8–12 GHz microwave frequencies, inductively coupled plasma-atomic emission spectrometry, Fourier transform infrared spectrometry, synchronized two thermal analyses, and 57 Fe Mössbauer spec-troscopy analysis of chalcedony, agate, and zultanite samples from Turkey are presented. Agate and chalcedony show t...
Article
Full-text available
In this study, high resolution radiation spectroscopy has been obtained using digital signal processing system, and radiation datas have been collected and saved via established measurement system based on computer which has both 14-bit resolution and 100MS/s real time sampling rate. The high resolution spectroscopy results of 137Cs radiation sourc...
Article
Full-text available
In materials research, especially in the case of nanomaterials, the option of performing the low-temperature Mössbauer spectroscopy measurements is very desirable. For this purpose, a new design of low-temperature Mössbauer spectrometer, working in the transmission mode, is introduced. The main part of the presented device is composed of a cryostat...
Article
Full-text available
In this study, an optional assembling of a Mössbauer spectrometer based on stand-alone instruments (an Agilent 33521A function generator and an Agilent DSO-X 2002A digital oscilloscope) is presented. The main goal is to identify the possible functional limits of selected instruments used as standard and cheap laboratory equipment in comparison to t...
Article
Full-text available
Alpha iron phthalocyanines (α-FePc) oxygenated at low temperatures were investigated with the help of 57Fe Mössbauer spectroscopy, magnetization measurements (SQUID) and X-ray diffractometry (XRD). Mössbauer spectroscopy revealed that upon oxygenation of α-FePc, new species were formed which could be associated with FeIIIPc oxygen adducts. Unexpect...
Article
Magnetization and low temperature in-field 57Fe Mössbauer spectroscopy measurements have been performed on a Fe[C(SiMe3)3]2/ferrihydrite hetero-mixture. The results indicate the presence of ferromagnetic coupling of magnetic moments involving Fe[C(SiMe3)3]2 with a hyperfine magnetic field of about 151 T, attributable mainly to the non-frozen atomic...
Article
The gamma-ray energy spectrum of 137 Cs was obtained according to different parameters such as preamplifier capacitance, the amplifier's coarse gain level, power supply voltage for the detector, and source-to-detector distance. This investigation was performed with both analogue and digital methods. In order to examine the effects of these paramete...
Article
Full-text available
Optimization of a linear motor and digital PID controller setup used in a Mössbauer spectrometer is presented. Velocity driving system with a digital PID feedback subsystem was developed in the LabVIEW graphical environment and deployed on the sbRIO real-time hardware device (National Instruments). The most important data acquisition processes are...
Article
Thermally induced oxidative decomposition of iron(II) acetate in air is presented as a simple route towards superparamagnetic maghemite nanoparticles the size of which can be controlled by the reaction temperature in the range of 320-400°C. Decomposition mechanism, the phase composition of the reaction products as well as their structural, magnetic...
Article
Full-text available
Speed of data processing is regarded as a crucial parameter in the nuclear physics experiment, where a dead time elimination or reduction is needed. In the case of computer-based systems, fast data processing algorithms are necessary to be exploited for saving a computational time and to reduce a total duration of the experiment. Time of measuremen...
Article
Full-text available
The preparation of nanoAg@montmorillonite composite materials and their catalytic activity is reported in this article. The nanoAg@montmorillonite composite materials were prepared by the adsorption of silver NPs, with an average size about 30 nm, from their aqueous dispersion onto two types of montmorillonite with different chemical composition. S...
Article
Full-text available
A new concept of Mssbauer spectrometer used for material research is presented. Performance of this computer based measurement system was carefully analyzed and programming code of the application step by step optimized. By implementation of parallel data processing the control application with zero dead-time of measurement was developed.
Chapter
This chapter reports on exploitation of 57Fe Mössbauer spectroscopy in the study of nanocrystalline iron(III) oxide polymorphs and amorphous Fe2O3 synthesized through thermally induced solid-state reactions. It describes polymorphs of iron(III) oxide are discussed in details with respect to their structural and magnetic properties and how they are...
Article
We present the first direct evidence that reactant particle size determines the mechanism of thermally induced solid-state reactions and can be used as the tuner of the product crystal structure. This control of the polymorphous character of the products through the particle size of precursor is demonstrated upon following the process of isothermal...
Article
Nanocomposites consisting of diatomaceous earth particles and silver nanoparticles (silver NPs) with high antimicrobial activity were prepared and characterized. For the purpose of nanocomposite preparation, silver NPs with an average size of 28nm prepared by modified Tollens process were used. Nanocomposites were prepared using poly(diallyldimethy...