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Hlupák, hňup, ťulpas a jiní
Karlíková, Helena
2024 - český
Klíčová slova:
Old Czech; etymology
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Hlupák, hňup, ťulpas a jiní
Numerical evaluation of mass-diffusive compressible fluids flows models
Bodnár, Tomáš; Fraunié, P.
2024 - anglický
This contribution presents first numerical tests of some recently published alternative models for solution of viscous compressible and nearly incompressible models. All models are solved by high resolution compact finite difference scheme with strong stability preserving RungeKutta time stepping. The two simple but challenging computational test cases are presented, based on the double-periodic shear layer and the Kelvin-Helmholtz instability. The obtained time-dependent flow fields are showing pronounced shear and vorticity layers being resolved by the standard as well as by the new mass-diffusive modified models. The preliminary results show that the new models are viable alternative to the well established classical models.
Klíčová slova:
compressible Navier-Stokes; nearly incompressible flow; mass diffusion; compact finite-difference
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Numerical evaluation of mass-diffusive compressible fluids flows models
This contribution presents first numerical tests of some recently published alternative models for solution of viscous compressible and nearly incompressible models. All models are solved by high ...
Motion of fluids in the moving domain
Nečasová, Šárka
2024 - anglický
It is a survay paper where the problem of the existence of weak solutions of compressible barotropic solutions in a moving bounded domain is studied.
Klíčová slova:
compressible fluid; moving domain; weak solutions
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Motion of fluids in the moving domain
It is a survay paper where the problem of the existence of weak solutions of compressible barotropic solutions in a moving bounded domain is studied.
Temoporfin-conjugated upconversion nanoparticles for NIR-induced photodynamic therapy of pancreatic cancer
Shapoval, Oleksandr; Větvička, D.; Kabešová, M.; Engstová, Hana; Horák, Daniel
2024 - anglický
Photodynamic therapy (PDT), a clinically approved cancer treatment strategy, has the potential to cure pancreatic cancer with minimal side effects. PDT primarily uses visible wavelengths to directly activate hydrophobic photosensitizers, which may be insufficient for deep-seated cancer cells in clinical practice due to poor penetration. Upconversion nanoparticles (UCNPs) serve as an indirect excitation source to activate photosensitizers (PSs) in the NIR region, overcoming the limitations of molecular PSs such as hydrophobicity, non-specificity, and excitation in the UV/Vis region. Here, monodisperse upconversion NaYF4:Yb3+, Er3+, Fe2+ nanoparticles (UCNPs) have been surface-engineered with poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) and temoporfin (mTHPC), a clinically used PDT prodrug, for near-infrared (NIR) light-triggered PDT of pancreatic cancer. The incorporation of Fe2+ ions into the particles increased the fluorescence intensity in the red region matching the activation wavelength of mTHPC. Covalent binding of mTHPC to the surface of UCNP@PMVEMA particles provided colloidally stable conjugates enabling generation of singlet oxygen. In vitro cytotoxicity and photodynamic activity of the particles were evaluated using INS-1E rat insulinoma and Capan-2 and PANC-01 human pancreatic adenocarcinoma cell lines. The PDT efficacy of UCNP@PMVEMA-mTHPC conjugates after irradiation with 980 nm NIR light was tested in vivo in a pilot study on Capan-2 human pancreatic adenocarcinoma growing subcutaneously in athymic nude mice. The intratumoral administration of the nanoconjugates significantly hindered tumor growth and demonstrated promising PDT efficacy against human pancreatic cancer.
Klíčová slova:
photodynamic therapy; temoporfin; upconversion nanoparticles
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Temoporfin-conjugated upconversion nanoparticles for NIR-induced photodynamic therapy of pancreatic cancer
Photodynamic therapy (PDT), a clinically approved cancer treatment strategy, has the potential to cure pancreatic cancer with minimal side effects. PDT primarily uses visible wavelengths to directly ...
PROPERTIES OF NANOCRYSTALLINE FE-NI PARTICLES PREPARED BY THERMAL REDUCTION OF OXALATE PRECURSORS
Švábenská, Eva; Roupcová, Pavla; Havlíček, Lubomír; Schneeweiss, Oldřich
2024 - anglický
Recent technological advancements require development of cost-effective and high-performance magnets \nwhich ideally do not contain rare earth metals or noble metals. The promising candidates are Fe-Ni-based \nalloys, in particular, the Fe50Ni50 L10 phase (tetrataenite), which has a great perspective for producing hard \nmagnetic materials. Our study explores a promising method for preparing nanoparticles of Fe-Ni alloy from an \niron-nickel oxalate precursor. The coprecipitation method was employed to prepare oxalate precursors, \nfollowed by controlled thermal decomposition in a reducing hydrogen atmosphere. The morphology and \nproperties of the resulting particles were analysed using scanning electron microscopy (SEM) coupled with \nenergy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Mössbauer spectroscopy (MS), and \nmagnetic measurements.\nThe SEM analysis revealed that the particles have approximately cube-shaped unit cell morphology with a\nsize in a range of 1 - 2 μm. Upon annealing, the samples contain multiple phases with varying Fe-Ni content.\nMagnetic measurements confirmed the formation of magnetically suitable Fe-Ni phases in the samples after \nannealing. Mössbauer spectroscopy emerged as a highly effective method for characterizing individual phases \nof the Fe-Ni system.
Klíčová slova:
Magnetic materials; thermal decomposition; Mössbauer spectroscopy
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
PROPERTIES OF NANOCRYSTALLINE FE-NI PARTICLES PREPARED BY THERMAL REDUCTION OF OXALATE PRECURSORS
Recent technological advancements require development of cost-effective and high-performance magnets \nwhich ideally do not contain rare earth metals or noble metals. The promising candidates are ...
EFFECT OF OXIDE DISPERSION ON ELECTRIC CONDUCTIVITY OF ROTARY SWAGED POWDER-BASED COPPER COMPOSITES
Kunčická, Lenka; Benč, Marek; Kačor, P.; Marek, M.
2024 - anglický
Copper is a very popular electro-conductive material, however, the mechanical properties of pure Cu are low. They can be typically improved by (micro)alloying, or via structure modifications introduced by optimized deformation and thermomechanical treatments. Designing a Cu-based composite, possibly strengthened by a dispersion of fine oxides, is another way how to favourably improve the strength properties of Cu. In this study, we performed mechanical alloying of a Cu powder with a powder of Al2O3 oxide, which is known to have strengthening effects on metallic materials. After mixing, we sealed the powder mixture into evacuated tubular Cu containers (i.e. cans). As for the consolidation procedure, we applied direct consolidation of the canned powders via the intensive plastic deformation method of rotary swaging, performed under warm conditions. Subsequently, we subjected the swaged conductors to measurements of electric conductivity and detailed structure observations. The results revealed that the applied swaging ratio was sufficient to fully consolidate the canned powders as the final conductor was unrecognizable from a cast alloy from the viewpoints of visual and structure assessment. In other words, the structure did not exhibit any voids or remnants of unconsolidated powder particles. The observed fine grains with homogeneous dispersion of Al2O3 oxide particles provided improvement of the mechanical properties, as proven by microhardness measurements. Moreover, the electric properties remained favourable.
Klíčová slova:
mechanical-properties; extrusion; Copper; oxide dispersion; electric conductivity; rotary swaging; microstructure
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
EFFECT OF OXIDE DISPERSION ON ELECTRIC CONDUCTIVITY OF ROTARY SWAGED POWDER-BASED COPPER COMPOSITES
Copper is a very popular electro-conductive material, however, the mechanical properties of pure Cu are low. They can be typically improved by (micro)alloying, or via structure modifications ...
Z českých slov a věcí: záchod, toaleta, aha
Janyšková, Ilona
2024 - český
Článek vysvětluje etymologii českých názvů záchod, toaleta, aha.
Klíčová slova:
etymology; Czech
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Z českých slov a věcí: záchod, toaleta, aha
Článek vysvětluje etymologii českých názvů záchod, toaleta, aha.
Železniční cestovatel Eduard Bazika aneb Cestování s manželkou
Hlavačka, Milan
2024 - český
Ing. Eduard Bazika (1830–1914) nebyl profesionální poutník, ale poutník z profese. Jako absolvent pražské polytechniky se celý život specializoval na železniční stavitelství a jako inženýr nejdříve státních drah a od roku 1855 až do odchodu na odpočinek v roce 1891 soukromé Společnosti státní dráhy (StEG) celý život procestoval, respektive před výstavbou prochodil svěřené železnice v české a moravské krajině. I po odchodu na penzi pracoval pro Zemský výbor Království českého a jeho Železniční výbor a v této pozici opět pracovně putoval po všech koutech Čech, aby posuzoval rentabilitu budoucích místních drah. Jeho zvláštností bylo, že se vždy snažil skloubit své cestovní povinnosti s rodinným životem, což mělo za následek, že jeho žena a děti putovaly s ním po nejrůznějších štacích a železničních stavbách. Stranou neponechával ani dlouhodobější náročnější soukromé cesty s manželkou na světové výstavy a po historických památkách Itálie (v doprovodu Jiřího Stibrala) či k obhlídce nově dokončených alpských železnicích. Jako představitel sebevědomé české střední třídy, která už disponovala volným časem a finančními prostředky (a samozřejmě režijní jízdenkou) dovedl skloubit cestovatelskou povinnost s cestovatelskou vášní a putování vnímal jako nezbytnou součást aktivního životního stylu moderního člověka. Ing. Eduard Bazika (1830–1914) was not a professional pilgrim, but a pilgrim by profession. As a graduate of the Prague Polytechnic, he specialized in railway construction all his life and as an engineer, first of all for the State railways, and from 1855 until his retirement in 1891, he traveled all his life for the private State Railway Company (StEG), or rather, before construction, he traveled the entrusted railways in the Bohemian and Moravian landscape. Even after retiring, he worked for the Land Committee of the Kingdom of Bohemia and its Railway Committee, and in this position he once again traveled to all corners of Bohemia to assess the profitability of future local railways. A peculiarity of his was that he always tried to combine his traveling duties with his family life, which resulted in his wife and children traveling with him to various estates and railway constructions. He did not leave aside longer, more demanding private trips with his wife to world exhibitions and historical monuments in Italy (accompanied by Jiří Stibral) or to inspect the newly completed Alpine railways. As a representative of the self-confident Czech middle class, who already had free time and financial resources (and, of course, an overhead ticket), he was able to combine the obligation to travel with a passion for travel and perceived traveling as a necessary part of the active lifestyle of a modern person.
Klíčová slova:
Ing Eduard Bazika; pilgrim by profession; railway
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Železniční cestovatel Eduard Bazika aneb Cestování s manželkou
Ing. Eduard Bazika (1830–1914) nebyl profesionální poutník, ale poutník z profese. Jako absolvent pražské polytechniky se celý život specializoval na železniční stavitelství a jako inženýr nejdříve ...
Modification of cooling system for laboratory measurement of rotor blade vibration
Maturkanič, Dušan; Procházka, Pavel; Hodboď, Robert; Voronova, Evgeniya; Mekhalfia, Mohammed Lamine
2024 - anglický
Last year, the replacement of the turbine wheel model was completed in the Laboratory of Rotational Laser Vibrometry of the Institute of Thermomechanics AS CR, v.v.i. Based on previous experience and the expected higher operating load planned for the new wheel, the cooling system was modified at the same time. The paper describes the main effort in this direction and the results that clarify the previous damage of the measuring device.
Klíčová slova:
blade; vibration; cooling system; measurement; laboratory
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Modification of cooling system for laboratory measurement of rotor blade vibration
Last year, the replacement of the turbine wheel model was completed in the Laboratory of Rotational Laser Vibrometry of the Institute of Thermomechanics AS CR, v.v.i. Based on previous experience and ...
Stochastic version of the arc-length method
Náprstek, Jiří; Fischer, Cyril
2024 - anglický
The solution of a nonlinear algebraic system using the incremental method, based on pre-defined loading steps, fails in the vicinity of local extrema as well as around bifurcation points. The solution involved the derivation of the so-called ’Arc-Length’ method. Its essence lies in not incrementing the system parameter or any of the independent variables but rather the length of the response curve. The stochastic variant of this method allows for working with a system where system parameters include random imperfections. This contribution presents a variant that tracks the first two stochastic moments. Even in this simple case, interesting phenomena can be observed, such as the disappearance of the energy barrier against equilibrium jump due to random imperfections in the system.
Klíčová slova:
random imperfection; stochastic arc-length method; continuation; numerical method
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Stochastic version of the arc-length method
The solution of a nonlinear algebraic system using the incremental method, based on pre-defined loading steps, fails in the vicinity of local extrema as well as around bifurcation points. The solution ...
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