spatial and volumetric modeling
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The liquid state NMR chemical shift of protons is a parameter frequently used to characterize host-guest complexes. Its theoretical counterpart, that is, the 1H NMR chemical shielding affected by the solvent (1H CS), may provide important insights into spatial arrangements of supramolecular systems, and it can also be reliably obtained for challenging cases of an aggregation of aromatic and antiaromatic molecules in solution. This computational analysis is performed for the complex of coronene and an antiaromatic model compound in acetonitrile by employing the GIAO-B3LYP-PCM approach combined with a saturated basis set. Predicted 1H CS values are used to generate volumetric data, whose properties are thoroughly investigated. The 1H CS isosurface, corresponding to a value of the proton chemical shift taken from a previous experimental study, is described. The presence of the 1H CS isosurface should be taken into account in deriving structural information about supramolecular hosts and their encapsulation of small molecules.
- Klíčová slova
- B3LYP, GIAO, antiaromaticity, chemical shielding, proton NMR,
- MeSH
- acetonitrily chemie MeSH
- difrakce rentgenového záření MeSH
- izotopy uhlíku MeSH
- magnetická rezonanční spektroskopie metody MeSH
- makromolekulární látky MeSH
- nikl chemie MeSH
- normální rozdělení MeSH
- polycyklické sloučeniny chemie MeSH
- protonová magnetická rezonanční spektroskopie MeSH
- protony MeSH
- rozpouštědla chemie MeSH
- železo chemie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- acetonitrile MeSH Prohlížeč
- acetonitrily MeSH
- Carbon-13 MeSH Prohlížeč
- coronene MeSH Prohlížeč
- izotopy uhlíku MeSH
- makromolekulární látky MeSH
- nikl MeSH
- polycyklické sloučeniny MeSH
- protony MeSH
- rozpouštědla MeSH
- železo MeSH
Wavelet transformation is one of the most frequent procedures for data denoising, smoothing, decomposition, features extraction, and further related tasks. In order to perform such tasks, we need to select appropriate wavelet settings, including particular wavelet, decomposition level and other parameters, which form the wavelet transformation outputs. Selection of such parameters is a challenging area due to absence of versatile recommendation tools for suitable wavelet settings. In this paper, we propose a versatile recommendation system for prediction of suitable wavelet selection for data smoothing. The proposed system is aimed to generate spatial response matrix for selected wavelets and the decomposition levels. Such response enables the mapping of selected evaluation parameters, determining the efficacy of wavelet settings. The proposed system also enables tracking the dynamical noise influence in the context of Wavelet efficacy by using volumetric response. We provide testing on computed tomography (CT) and magnetic resonance (MR) image data and EMG signals mostly of musculoskeletal system to objectivise system usability for clinical data processing. The experimental testing is done by using evaluation parameters such is MSE (Mean Squared Error), ED (Euclidean distance) and Corr (Correlation index). We also provide the statistical analysis of the results based on Mann-Whitney test, which points out on statistically significant differences for individual Wavelets for the data corrupted with Salt and Pepper and Gaussian noise.
- Klíčová slova
- Coiflet wavelet, Daubechies wavelet, Symlet wavelet, spatial and volumetric modeling, wavelet transformation,
- MeSH
- algoritmy * MeSH
- elektromyografie * MeSH
- lidé MeSH
- magnetická rezonanční tomografie * MeSH
- normální rozdělení MeSH
- počítačová rentgenová tomografie * MeSH
- vlnková analýza * MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Mortars and concretes are ubiquitous materials with very complex hierarchical microstructures. To fully understand their main properties and to decrease their CO2 footprint, a sound description of their spatially resolved mineralogy is necessary. Developing this knowledge is very challenging as about half of the volume of hydrated cement is a nanocrystalline component, calcium silicate hydrate (C-S-H) gel. Furthermore, other poorly crystalline phases (e.g. iron siliceous hydrogarnet or silica oxide) may coexist, which are even more difficult to characterize. Traditional spatially resolved techniques such as electron microscopy involve complex sample preparation steps that often lead to artefacts (e.g. dehydration and microstructural changes). Here, synchrotron ptychographic tomography has been used to obtain spatially resolved information on three unaltered representative samples: neat Portland paste, Portland-calcite and Portland-fly-ash blend pastes with a spatial resolution below 100 nm in samples with a volume of up to 5 × 104 µm3. For the neat Portland paste, the ptychotomographic study gave densities of 2.11 and 2.52 g cm-3 and a content of 41.1 and 6.4 vol% for nanocrystalline C-S-H gel and poorly crystalline iron siliceous hydrogarnet, respectively. Furthermore, the spatially resolved volumetric mass-density information has allowed characterization of inner-product and outer-product C-S-H gels. The average density of the inner-product C-S-H is smaller than that of the outer product and its variability is larger. Full characterization of the pastes, including segmentation of the different components, is reported and the contents are compared with the results obtained by thermodynamic modelling.
A mathematical modelling approach for open-tubular capillary electrochromatography is presented. The spatially one-dimensional model takes into account (i) a coupling of (non)linear adsorption of positively or negatively charged analyte molecules (at a negatively charged capillary inner surface) with the equilibrium electrokinetics at this solid-liquid interface, (ii) mobile phase transport by electroosmosis and pressure-driven flow, as well as (iii) transport of species by electrophoresis and molecular diffusion. Under these conditions the local zeta-potential and electroosmotic mobility become a function of the concentration of the charged analyte. The resulting inhomogeneity of electroosmotic flow through the capillary produces a compensating pore pressure as requirement for incompressible mobile phase flow (i.e., for constant volumetric flow along the capillary). The results of the simulations are discussed in view of the surface-to-volume ratio of the capillary lumen, the analyte concentration (in combination with a Langmuir isotherm for the adsorption process), and buffer effects.
