No (11880)
Yes (2918)
Number of found documents:
14798
Published from
to
Stochastic version of the arc-length method
Náprstek, Jiří; Fischer, Cyril
2024 - English
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.
Keywords:
random imperfection; stochastic arc-length method; continuation; numerical method
Available in digital repository of the ASCR
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 ...
Acoustic emission methods in steel bridge degradation identification and monitoring
Šorm, Filip
2024 - English
Acoustic emission methods proved to be an effective diagnostic tool in many industrial sectors. The potential of this method in the field of steel bridge diagnostics is explored in this article. The goal is to find the most effective use of this method.
Keywords:
steel bridges; diagnostics; acoustic emission
Available in digital repository of the ASCR
Acoustic emission methods in steel bridge degradation identification and monitoring
Acoustic emission methods proved to be an effective diagnostic tool in many industrial sectors. The potential of this method in the field of steel bridge diagnostics is explored in this article. The ...
Financial skills and search in the mortgage market
Cota, Marta; Šterc, Ante
2024 - English
Are households with low financial skills disadvantaged in the mortgage market? Using stochastic record linking, we construct a unique U.S. dataset encompassing a rich set of mortgage details and borrowers’ characteristics, including their objective financial literacy measure. We find that households with low financial literacy are up to 4% more likely to search less and lock in at 15-20 b.p. higher rates. Upon origination, unskilled borrowers face a 35-45% higher mortgage delinquency and end up with a 30% lower likelihood of refinancing. Overall, for a $100,000 loan, the potential losses from low financial literacy are more than $9,329 over the mortgage duration. To understand how financial education, more accessible mortgages, or mortgage rate changes affect households with low financial literacy, we formulate and calibrate a mortgage search model with heterogeneous search frictions and endogenous financial skills. Our model estimates show that search intensity and financial skill variations contribute to 55% and 10% of mortgage rate variations, respectively. We find that i) more accessible mortgages lead to a higher delinquency risk among low-skilled households, ii) financial education mitigates the adverse effects of increased accessibility, and iii) low mortgage rates favor high-skilled homeowners and, by reinforcing refinancing activity, deepen consumption differences across different financial skill levels.
Keywords:
mortgage refinancing; mortgage search; financial skills
Fulltext is available at external website.
Financial skills and search in the mortgage market
Are households with low financial skills disadvantaged in the mortgage market? Using stochastic record linking, we construct a unique U.S. dataset encompassing a rich set of mortgage details and ...
PROPERTIES OF NANOCRYSTALLINE FE-NI PARTICLES PREPARED BY THERMAL REDUCTION OF OXALATE PRECURSORS
Švábenská, Eva; Roupcová, Pavla; Havlíček, Lubomír; Schneeweiss, Oldřich
2024 - English
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.
Keywords:
Magnetic materials; thermal decomposition; Mössbauer spectroscopy
Available at various institutes of the ASCR
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 ...
Electrochemistry of Acetaminophen
Mikysek, T.; Ludvík, Jiří
2024 - English
The contribution is focused on electrochemical oxidation of acetaminophen mainly in non-aqueous media. The influence of various organic solvents as well as the pH effect is described herein. The redox properties of acetaminophen were studied by means of cyclic voltammetry, and rotating-disk voltammetry. We found that the protonation/deprotonation of acetaminophen acts as a ratedetermining step, where the stability of phenoxy radical intermediate plays an important role.
Keywords:
acetaminophen; phenacetine; voltammetry
Available on request at various institutes of the ASCR
Electrochemistry of Acetaminophen
The contribution is focused on electrochemical oxidation of acetaminophen mainly in non-aqueous media. The influence of various organic solvents as well as the pH effect is described herein. The redox ...
Temoporfin-conjugated upconversion nanoparticles for NIR-induced photodynamic therapy of pancreatic cancer
Shapoval, Oleksandr; Větvička, D.; Kabešová, M.; Engstová, Hana; Horák, Daniel
2024 - English
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.
Keywords:
photodynamic therapy; temoporfin; upconversion nanoparticles
Available in digital repository of the ASCR
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 ...
A New Approach to Determining the Drug Guaifenesin Using Voltammetric and Flow Injection Analysis
Kelíšková, P.; Matvieiev, O.; Sokolová, Romana; Janíková, L.; Behúl, M.; Šelešovská, R.
2024 - English
This study presents a new method for detecting guaifenesin (GFE) in pharmaceutical samples. We employed screen-printed sensors with a boron-doped diamond electrode (BDDE) to develop and validate both voltammetric and flow amperometric methods. These approaches were effectively used to analyze model solutions, pharmaceutical preparations, and serum samples spiked with GFE, producing accurate results comparable to those obtained with HPLC/DAD analysis. The developed methods provide straightforward, sensitive, and selective means for determining GFE in various sample matrices, underscoring the potential of SP/BDDE in electrochemical analysis.
Keywords:
guaifenesin; screen-printed sensor; boron-doped diamond electrode
Available on request at various institutes of the ASCR
A New Approach to Determining the Drug Guaifenesin Using Voltammetric and Flow Injection Analysis
This study presents a new method for detecting guaifenesin (GFE) in pharmaceutical samples. We employed screen-printed sensors with a boron-doped diamond electrode (BDDE) to develop and validate both ...
Optimization of Parameters Used in the Application of Elimination Voltammetry with Linear Scan
Navrátil, Tomáš; Trnková, L.; Hrdlička, Vojtěch; Li, X.
2024 - English
Elimination Voltammetry with Linear Scan (EVLS) is a well-established mathematical method that aids in understanding an analyzed electrochemical system. In almost 30 years since its derivation, it has become a “black-box” technique that is applied automatically (in most cases due to its incorporation into a voltammetric software) without thinking about its fundamentals. However, the choice of optimum parameters under which DC voltammetric data (from which elimination curves are calculated) is crucial. This contribution deals with revealing the optimum ratio of applied scan rates and their absolute values (i.e., times of recording) in dependence on the character of the investigated system (diffusion-controlled process, adsorption-controlled process, etc.).
Keywords:
elimination voltammetry with linear scan; optimization; adsorption
Available on request at various institutes of the ASCR
Optimization of Parameters Used in the Application of Elimination Voltammetry with Linear Scan
Elimination Voltammetry with Linear Scan (EVLS) is a well-established mathematical method that aids in understanding an analyzed electrochemical system. In almost 30 years since its derivation, it has ...
Multi-Annual Characterization of PM1 Aerosol Optical Properties and Size Distribution at the Peri-Urban Atmospheric Site ATOLL in Lille
Suchánková, Lenka
2024 - English
The aim of this study is to present aerosol scattering, absorption properties and particle number size distribution in PM1 in years 2018-\n2022 at peri-urban atmospheric site Atmospheric Observations in LiLLE (ATOLL) in Lille, France. This study is the first to present results dedicated to aerosol scattering properties at this site.
Keywords:
aerosol particles; PM1; temporal trends
Available in digital repository of the ASCR
Multi-Annual Characterization of PM1 Aerosol Optical Properties and Size Distribution at the Peri-Urban Atmospheric Site ATOLL in Lille
The aim of this study is to present aerosol scattering, absorption properties and particle number size distribution in PM1 in years 2018-\n2022 at peri-urban atmospheric site Atmospheric Observations ...
Development of Continuous Technology for the Preparation of Pharmaceuticals
Jaklová, Natalie
2024 - English
The present research focuses on the transition of a batch reaction assisted by phase transfer catalyst (PTC) into continuous process. The first reaction studied was an N-alkylation reaction with methyl ester of the 1-methyl-10α-methoxydihydrolysergic acid (MeLUME) as product. MeLUME is one of the intermediates in synthesis of drug Nicergoline. The N-alkylation occurs in two different immiscible phases and the bridge between these phases is the phase transfer catalyst. The study was performed in several different continuous flow apparatuses. The best results were obtained in a capillary reactor, with assistance of ultrasound.
Keywords:
continualization; ultrasound; pharmaceuticals
Available in a digital repository NRGL
Development of Continuous Technology for the Preparation of Pharmaceuticals
The present research focuses on the transition of a batch reaction assisted by phase transfer catalyst (PTC) into continuous process. The first reaction studied was an N-alkylation reaction with ...
NRGL provides central access to information on grey literature produced in the Czech Republic in the fields of science, research and education. You can find more information about grey literature and NRGL at service web
Send your suggestions and comments to nusl@techlib.cz
Provider
Other bases