Number of found documents: 587
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Characterization of titanium laser welds
Chmelíčková, H.; Hiklová, H.; Václavek, L.; Tomáštík, J.; Čtvrtlík, Radim
2020 - English
Butt welding of commercially pure titanium Grade 1 and Ti6Al4V alloy sheets using a pulsed Nd:YAG laser KLS 246 - 102 LASAG were carried out to determine optimal values of pulse energy and pulse length to create completely penetrated weld. Surface peak power density of about 3.105 W.cm−2 was found as an optimal value. Weld dimensions, both face width and penetration depth, are found to be proportional to increasing energy and decreasing pulse length. Gentle sagging and root penetration were revealed by means of contact surface profilometry. The nanohardness tests on transverse cross-sections detected approximately 50% higher hardness in the fusion zone than in the base material.\n Keywords: elasticity; laser welding; nanohardness; surface profile; titanium Available at various institutes of the ASCR
Characterization of titanium laser welds

Butt welding of commercially pure titanium Grade 1 and Ti6Al4V alloy sheets using a pulsed Nd:YAG laser KLS 246 - 102 LASAG were carried out to determine optimal values of pulse energy and pulse ...

Chmelíčková, H.; Hiklová, H.; Václavek, L.; Tomáštík, J.; Čtvrtlík, Radim
Fyzikální ústav, 2020

Fracture behavior of FeAlSi intermetallics
Čech, J.; Haušild, P.; Karlík, M.; Nová, K.; Průša, F.; Novák, P.; Kopeček, Jaromír
2020 - English
The study is devoted to the intermetallic alloy FeAl20Si20 (wt.%) with the potential applications in high temperature aggressive environments. The samples of the same chemical composition were prepared by spark plasma sintering from the different mechanically alloyed powders (pure elements and pre-alloyed powders). Keywords: FeAlSi; fracture toughness; nanoindentation; SPS Available at various institutes of the ASCR
Fracture behavior of FeAlSi intermetallics

The study is devoted to the intermetallic alloy FeAl20Si20 (wt.%) with the potential applications in high temperature aggressive environments. The samples of the same chemical composition were ...

Čech, J.; Haušild, P.; Karlík, M.; Nová, K.; Průša, F.; Novák, P.; Kopeček, Jaromír
Fyzikální ústav, 2020

Mathematical method for submolecular resolution of helicene-based macrocycles by atomic force microscopy in air
Ukraintsev, Egor; Houska, Václav; Vacek, Jaroslav; Starý, Ivo; Stará, Irena G.; Rezek, B.
2020 - English
We introduce a straightforward mathematical method for improving the AFM image resolution, applied to image analysis of helicene-based macrocycles adsorbed on HOPG. The method reveals structural details from insufficiently resolved AFM images and attributes them to internal structure and ordering of the macrocycles. Our findings are also corroborated by molecular mechanics simulations, validating that the structure provided by the method has lower potential energy compared to other tested macrocycle arrangements. Keywords: atomic force microscope; mathematical modeling; submolecular resolution; macrocycles; molecular mechanics simulations Available at various institutes of the ASCR
Mathematical method for submolecular resolution of helicene-based macrocycles by atomic force microscopy in air

We introduce a straightforward mathematical method for improving the AFM image resolution, applied to image analysis of helicene-based macrocycles adsorbed on HOPG. The method reveals structural ...

Ukraintsev, Egor; Houska, Václav; Vacek, Jaroslav; Starý, Ivo; Stará, Irena G.; Rezek, B.
Fyzikální ústav, 2020

Závěrečná zpráva projektu „Efektivní využití odpadního tepla“ reg. č. CZ.07.1.02/0.0/0.0/16_040/0000384 realizovaném v rámci výzvy č. 24 OP PPR, technologie 1, mobilní zdroje odpadního tepla
Knížek, Karel; Stachura, Jan
2020 - Czech
Cílem projektu bylo ověřit možnost využití termoelektrických generátorů (dále TEG) k výrobě elektrické energie z odpadního tepla, které je produkováno spalováním fosilního paliva v dopravních prostředcích. S ohledem na charakter jízdního cyklu prostředků veřejné dopravy jsme se na základě konzultací a prozkoumání možností experimentálního testování soustředili na ověření možnosti lepšího využití energie produkované nezávislým topením (NT) s cílem alespoň částečného pokrytí jeho potřeby elektrické energie, která je nutná k jeho provozu. Při provozu NT v autobuse dochází totiž k odběru elektrické energie cca 360 W z elektrické soustavy autobusu, která je potřeba pro pohon oběhového čerpadla, ventilátorů topení a řídící elektroniky NT.\n 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.\n Keywords: využití odpadního tepla; termoelektrická konverse Available at various institutes of the ASCR
Závěrečná zpráva projektu „Efektivní využití odpadního tepla“ reg. č. CZ.07.1.02/0.0/0.0/16_040/0000384 realizovaném v rámci výzvy č. 24 OP PPR, technologie 1, mobilní zdroje odpadního tepla

Cílem projektu bylo ověřit možnost využití termoelektrických generátorů (dále TEG) k výrobě elektrické energie z odpadního tepla, které je produkováno spalováním fosilního paliva v dopravních ...

Knížek, Karel; Stachura, Jan
Fyzikální ústav, 2020

Comparison of microbial interactions of zinc oxide nanomaterials in various size and shape
Rutherford, D.; Jíra, J.; Mičová, J.; Remeš, Zdeněk; Hsu, H.S.; Rezek, B.
2020 - English
Zinc oxide nanoparticles (ZnO NP) have shown great potential as a novel antibacterial material at a time when resistance towards conventional antibiotics is becoming more prevalent. We report bacteria inactivation by ZnO NP with novel hedgehog-like morphology using model gram-negative (E. coli) and gram-positive (S. aureus) bacteria. E. coli exposed to the novel ZnO hedgehog NP during growth resulted in 4 orders of magnitude reduction in viable cell concentration after 24 h, which is more than 2 orders higher reduction compared to commercially available ZnO NPs with nominal sizes from 50 nm to 20 um. There was a positive correlation between hedgehog NP concentration and bacteria cell concentration reduction within the range tested 0.1 – 1.0 mg/mL. S. aureus was less sensitive to ZnO NP exposure and inactivation effect of various ZnO NP, was comparable. The effect can be thus attributed to direct mechanical damage of the bacterial mebrane that is the most effective for the novel hedgehog ZnO NP. This conclusion was corroborated also by disk diffusion assays.\n Keywords: nanotechnology; microbiology; zinc oxide Available at various institutes of the ASCR
Comparison of microbial interactions of zinc oxide nanomaterials in various size and shape

Zinc oxide nanoparticles (ZnO NP) have shown great potential as a novel antibacterial material at a time when resistance towards conventional antibiotics is becoming more prevalent. We report bacteria ...

Rutherford, D.; Jíra, J.; Mičová, J.; Remeš, Zdeněk; Hsu, H.S.; Rezek, B.
Fyzikální ústav, 2020

Why monitor acoustic emissions during nanomechanical tests?
Čtvrtlík, Radim; Václavek, L.; Tomáštík, J.
2020 - English
Acoustic Emissions (AE) monitoring has been proved as an effective non-destructive technique at the macro scale. Nevertheless, it may also be employed at nano/micro scale during nanomechanical and nanotribological testing. Local mechanical properties of surfaces or micro object are routinely explored using nanoindentation, scratch test or dynamic impact tests that are evaluated based on analysis of depth-load-time records or microscopic observation of residual indents, scratch grooves or impact craters, respectively. Although these approaches have been proven to be sufficient in most cases for a variety of materials, there are many situations where they do not provide sufficient information for a complex understanding of the deformation response. On the other hand, analysis of AE signals generated during these tests may provide valuable complementary information and provide some insight into the dynamics of phenomena like cracking, phase transitions, plastic instabilities, etc.\n Keywords: acoustic emission; indentation; scratch test; thin films Available at various institutes of the ASCR
Why monitor acoustic emissions during nanomechanical tests?

Acoustic Emissions (AE) monitoring has been proved as an effective non-destructive technique at the macro scale. Nevertheless, it may also be employed at nano/micro scale during nanomechanical and ...

Čtvrtlík, Radim; Václavek, L.; Tomáštík, J.
Fyzikální ústav, 2020

Role of Urbach Energy in Photovoltaics
Vlk, Aleš; Abelová, Lucie; Hájková, Zdeňka; Remeš, Zdeněk; Holovský, Jakub; Ledinský, Martin
2020 - English
Organic-inorganic halide perovskites provide new opportunities for improvement of optoelectronic device performance, especially the efficiency of solar cells. To evaluate the quality of a new material many parameters has to be taken into account. Here, we discuss one of the often overlooked semiconductor’s parameters, Urbach energy, which is an easily accessible measure of material disorder. Moreover, we present its importance on the example of organic-inorganic halide perovskites. Keywords: organic-inorganic halide perovskites; photoluminescence; Urbach energy Available at various institutes of the ASCR
Role of Urbach Energy in Photovoltaics

Organic-inorganic halide perovskites provide new opportunities for improvement of optoelectronic device performance, especially the efficiency of solar cells. To evaluate the quality of a new material ...

Vlk, Aleš; Abelová, Lucie; Hájková, Zdeňka; Remeš, Zdeněk; Holovský, Jakub; Ledinský, Martin
Fyzikální ústav, 2020

Studium tepelných vlastností deagregovaných detonačních nanodiamantů metodami DSC-TG-MS
Zemenová, Petra; Král, Robert; Henych, Jiří; Stehlík, Štěpán
2020 - Czech
Příspěvek se zabýval studiem tepelných procesů u různě zpracovaných a frakcionovaných vzorků deagregovaných detonačních nanodiamantů metodami termických analýz (DSC-diferenční skenovací kalorimetrie a TG-termogravimetrie) a analýzy plynných produktů (MS-hmotová spektrometrie). This contribution deals with the study of thermal processes in different samples of detonation nanodiamond by thermal analyses (DSC-differential scanning calorimetry and TG-thermogravimetry) coupled with evolved gas analysis (EGA) by mass spectroscopy (MS). Keywords: degraded detonation nanodiamonds; thermal analysis Available at various institutes of the ASCR
Studium tepelných vlastností deagregovaných detonačních nanodiamantů metodami DSC-TG-MS

Příspěvek se zabýval studiem tepelných procesů u různě zpracovaných a frakcionovaných vzorků deagregovaných detonačních nanodiamantů metodami termických analýz (DSC-diferenční skenovací kalorimetrie a ...

Zemenová, Petra; Král, Robert; Henych, Jiří; Stehlík, Štěpán
Fyzikální ústav, 2020

Benefits of use of acoustic emission in scratch testing
Václavek, L.; Tomáštík, Jan; Chmelíčková, H.; Čtvrtlík, R.
2020 - English
Scratch test is regularly used for assessment of cohesive and adhesive strength of thin films and coatings. By default, its evaluation is based on analysis of depth-load-time record and microscopic observation of residual scratch groove. The visual analysis of the residual groove provides the most detailed description of the final damage of the surface (crack patterns, extent of plastic deformation, delamination, etc.), but it may be a time demanding approach. Although the continuous recording of indenter penetration depth and applied load offers instantaneous information about the performance of the tested material, it may not provide sufficient description of the sample’s deformation behaviour. Therefore, other complementary techniques for description of the deformation response to scratch loading are desirable. Keywords: acoustic emission; laser cladding; scratch test; thin films Available at various institutes of the ASCR
Benefits of use of acoustic emission in scratch testing

Scratch test is regularly used for assessment of cohesive and adhesive strength of thin films and coatings. By default, its evaluation is based on analysis of depth-load-time record and microscopic ...

Václavek, L.; Tomáštík, Jan; Chmelíčková, H.; Čtvrtlík, R.
Fyzikální ústav, 2020

Adhesion improvement between bitumen and mineral aggregate:theoretical principles and their impact on pavement structure lifetime
Trejbal, J.; Demo, Pavel; Nežerka, V.; Sveshnikov, Alexey; Valentová, T.; Valentin, J.
2019 - English
Influence of nanomaterial-based adhesion promoters on maximizing of intermolecular interactions between bitumen and aggregate surfaces was studied. Topological and physico-chemical properties were described and it is shown that presence of promoters increases adhesion about 18%. Keywords: adhesion promoters; interface interactions Available at various institutes of the ASCR
Adhesion improvement between bitumen and mineral aggregate:theoretical principles and their impact on pavement structure lifetime

Influence of nanomaterial-based adhesion promoters on maximizing of intermolecular interactions between bitumen and aggregate surfaces was studied. Topological and physico-chemical properties were ...

Trejbal, J.; Demo, Pavel; Nežerka, V.; Sveshnikov, Alexey; Valentová, T.; Valentin, J.
Fyzikální ústav, 2019

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