Final report of the project Effective use of waste heat reg. No. CZ.07.1.02 / 0.0 / 0.0 / 16_040 / 0000384 implemented within the call No. 24 OP PPR, technology 1, mobile sources of waste heat.

The aim of the project was to verify the possibility of using thermoelectric generators (TEG) to produce electricity from waste heat, which is produced by fossil fuel combustion in vehicles. Regarding the character of the public transport cycle and based on consultations and exploring experimental testing, we have focused on the possible improvement of the utilization of the energy that is produced by independent heater (IT) in order to at least partially cover the electric consumption needed for the running of the IT. During the operation of the IT in the bus, approximately 360 W of electricity is taken from the bus's electrical system, which is needed to drive the circulation pump, the heating fans and the IT control electronics.\

New Tc-tuned magnetic nanoparticles for self-controlled hyperthermia

Manganese perovskite nanoparticles of the XRD size in the range of 30–49 nm were synthesized via sol–gel technique employing citric acid and ethylene glycol. Their magnetic properties were investigated in the static and alternating magnetic fields..

Příprava Mn-Zn feritových nanočástic a jejich silikou obalené klastry: magnetické vlastnosti a transverzální relaxivita

Hydrothermal synthesis of Mn1-xZnxFe2O4 nanoparticles followed by encapsulation of this material into silica is demonstrated as a fast and facile method for preparation of efficient negative contrast agents based on clusters of ferrite crystallites. At first, the hydrothermal procedure was optimized to achieve strictly single-phase magnetic nanoparticles of Mn-Zn ferrites in the compositional range of x ≈ 0.2–0.6 and with the mean size of crystallites ≈10 nm. The products were characterized by powder X-ray diffraction, X-ray fluorescence spectroscopy, and SQUID magnetometry, and the composition close to x = 0.4 was selected for the preparation of silica-coated clusters with the mean diameter of magnetic cores ≈25 nm. Their composite structure was studied by means of transmission electron microscopy combined with detailed image analysis and magnetic measurements in DC fields. The relaxometric studies, performed in the magnetic field of B0 = 0.5 T, revealed high transverse relaxivity (r2(20 °C) = 450 s-1 mmol(Me3O4)-1 L) with a pronounced temperature dependence, which correlates with the observed temperature dependence of magnetization.Hydrotermální syntéza Mn1-xZnxFe2O4 nanočástic následovaná enkapsulací tohoto materiálu do siliky je demonstrována jako rychlá a snadná metoda pro přípravu účinných negativních kontrastních agents na bázi klastrů feritových krystalitů. Nejdříve byl hydrotermální postup optimalizován tak, aby bylo dosaženo čistě jednofázových magnetických nanočástic Mn-Zn feritů v rozmezí složení x ≈ 0,2-0,6 a se střední velikostí krystalitů ≈10 nm. Tyto produkty byly charakterizovány práškovou rentgenovou difrakcí, rentgenovou fluorescenční spektroskopií a SQUID magnetometrií a složení blízké k x = 0,4 bylo vybráno pro přípravu silikou obalených klastrů se středním průměrem magnetických jader ≈25 nm. Jejich kompozitní struktura byla studována pomocí transmisní elektronové mikroskopie kombinované s podrobnou obrazovou analýzou a magnetických měření v DC polích. Relaxometrické studie, provedené v magnetickém poli B0 = 0,5 T, ukázaly vysokou příčnou relaxivitu (r2(20 °C) = 450 s-1 mmol (Me3O4)-1 L) s výraznou teplotní závislostí magnetizace

Magnetoconductivity of the La 1–xSrxMnO3@TiO2 Nanocomposite

This paper deals with tunneling magnetoresistance in a composite system of the so-called 0–3 connectivity, in which ferromagnetic (FM) metallic nanoparticles La1–xSrxMnO3 (0-D objects) are embedded in the (3-D) insulating matrix of TiO2. The sample fabrication included the sol–gel preparation of manganite particles of the x = 0.35 composition and 25 nm mean crystallite size, their coating by TiO2, and compacting the products by spark plasma sintering (SPS). A comparative nanogranular sample was prepared by SPS of bare manganite particles. The resistivities of the composite and comparative samples are 100 000 and 100 times higher compared to those of bulk metallic La1–xSrxMnO3. Otherwise, the temperature dependence observed in the nanogranular La1–xSrxMnO3 sample is similar to single crystal data, and marked localization is absent also in the La1–xSrxMnO3@TiO2 nanocomposite. The data taken in applied fields up to 4 T reveal effects typical for grain-boundary tunneling in manganites, namely, the coexistence of the low-field magnetoconductance (LFMC), reflecting the field-induced alignment of FM cores, and high-field linear magnetoconductance (HFMC) that is generally ascribed to the effect of spin canting at localized Mn4+ sites in the interface. This is considered as a signature for resonant tunneling of spin-polarized carriers, theoretically treated by Lee et al [1]. The present results show that the total extent of LFMC makes 45% in the La1–xSrxMnO3@TiO2 nanocomposite and 21% in the La1–xSrxMnO3 nanogranular sample. The slope of HFMC has been determined to 5.4% and 4.9% per Tesla, respectively. The large LFMC effect observed in the nanocomposite exceeds the theoretical prediction of 33% for the second-order tunneling, which might suggest for higher order tunneling via resonant states

Influence of the structure on electric and magnetic properties of La0.8Na0.2Mn1−xCoxO3 perovskites

The influence of the cobalt substitution for manganese ions in the mixed valence perovskites La0.8Na0.2Mn1−xCoxO3 (0<= x <= 0.2) was investigated by X-ray, electric transport and magnetic measurements. The study carried out on sintered polycrystalline samples revealed the rhombohedral..

The Effects of Ultrasound Treatment of Graphite on the Reversibility of the (De)Intercalation of an Anion from Aqueous Electrolyte Solution

Low cycling stability is one of the most crucial issues in rechargeable batteries. Herein, we study the effects of a simple ultrasound treatment of graphite for the reversible (de)intercalation of a ClO4&minus; anion from a 2.4 M Al(ClO4)3 aqueous solution. We demonstrate that the ultrasound-treated graphite offers the improved reversibility of the ClO4&minus; anion (de)intercalation compared with the untreated samples. The ex situ and in situ Raman spectroelectrochemistry and X-ray diffraction analysis of the ultrasound-treated materials shows no change in the interlayer spacing, a mild increase in the stacking order, and a large increase in the amount of defects in the lattice accompanied by a decrease in the lateral crystallite size. The smaller flakes of the ultrasonicated natural graphite facilitate the improved reversibility of the ClO4&minus; anion electrochemical (de)intercalation and a more stable electrochemical performance with a cycle life of over 300 cycles