National Repository of Grey Literature 46 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
HDO Raman spectrum
Šubr, Martin ; Štěpánek, Josef (advisor) ; Procházka, Marek (referee)
Title: HDO Raman spectrum Author: Martin Šubr Department: Institute of Physics of Charles University Supervisor: Prof. RNDr. Josef Štěpánek, CSc., Institute of Physics of Charles University Abstract: The main aim of this thesis is to determine the HDO Raman spectrum. This spectrum cannot be measured separately in its liquid form, but it is possible to obtain it by a specific mathematical processing of sets of measured spectra with different H/D ratios. In this work we measured Raman spectra of liquid water with different mole fractions of water and heavy water, which were evaluated by factor analysis. Except for well-known spectra of water and heavy water, spectrum of HDO was determined. For fitting of this spectrum and its analysis, model with equilibrium constant and linear correction of the spectral shape with respect to the relative ratio of D was used. Keywords: Raman scattering, water and heavy water, HDO, factor analysis
Function of Magnesium Ions in the Formation of Biologically-Active Nucleic Acids Structures
Espinoza Herrera, Shirly Josefina ; Štěpánek, Josef (advisor) ; Mašek, Vlastimil (referee) ; Setnička, Vladimír (referee)
ESPINOZA HERRERA S.J. - DOCTORAL THESIS - FUNCTION OF MAGNESIUM IONS IN THE FORMATION OF BIOLOGICALLY-ACTIVE NUCLEIC ACIDS STRUCTURES ____________________________________________________________________ ABSTRACT Interaction of magnesium ions, the divalent ions with the highest concentration inside living cells, with the key biomolecules of nucleic acids was studied with aim to find out structural details of the interaction mechanism and effect of the magnesium ions presence on the nucleic-acid structure and structural transitions. Raman spectroscopy was chosen as the main experimental method, some complementary measurements of UV absorption spectra were also performed. Basic analyses of the spectral series obtained as a function of temperature and/or for various concentrations of Mg2+ ions were done by means of factor analysis. Where possible the factor analysis outputs were used for fits of appropriate thermodynamic equations. For the studies, various nucleic-acid molecular models were employed, in particular complementary RNA homopolynucleotides polyA and polyU, DNA homopolynucleotides polydA and polydT and RNA 14-mer oligonucleotide representing the apical hairpin of the TAR segment of HIV-1 genomic RNA. We have confirmed via Raman spectroscopy that magnesium ions added to a solution of polyA-polyU...
Comprehensive characterization of cellular suspensions by means of elastic light scattering
Macháň, Radek ; Štěpánek, Josef (advisor) ; Plášek, Jaromír (referee)
Studies of yeast Saccharomyces cerevisiae - a model eukaryot organism - often require determining the number of cells in a suspension. One of the methods often used for studying cell suspensions is the measuring of elastic scattering of light passing through the suspensions. Usual output of those measurements is the angular dependency of the intensity of scattered light, which bears information about the size of scatterers. This thesis studies time-dependencies of the intensity of scattered light and relationship of their statistical properties to the number of scatterers in a unit volume. For this purpose a simple model was proposed, which describes the connection between this quantity for a monodisperse suspension and the dependency of standard deviation of time-behaviour of the scattered intensity on the mean value of the same time-behaviour. An apparatus for computer controlled measurements of angular and timedependencies of scattered light intensity was completed for carrying out the experiments. Elastic scattering was measured on suspensions of yeast Saccharomyces cerevisiae and a model system (suspensions of 8m polymer particles). Experimental data were interpreted within the proposed model. Although yeast suspensions cannot be regarded as monodisperse, experimental data were in a good agreement with...
Improved determination of DNA duplex stability by using UV spectroscopy
Víšová, Ivana ; Štěpánek, Josef (advisor) ; Kočišová, Eva (referee)
This work deals with determination of thermodynamic parameters concerning the temperature induced decomposition of DNA duplexes. Precise temperature dependences of solution UV absorption spectra have been measured for several concentrations. Proposals and tests of various data analysis procedures, with aim to find out optimal way how to determine the thermodynamic potentials changes, represent the core of the work. It has been demonstrated that the combination of a factor analysis and a fit of thermodynamic equations to temperature dependences of obtained coefficient values, enables these parameters to be obtained from a measurement performed for only one concentration and with better precision than by using the so far recommended method based on a melting temperature determination for several concentrations.
Spectroscopic study of key biomolecular interactions for therapeutic applications of modified oligonucleotids
Kříž, Martin ; Štěpánek, Josef (advisor) ; Bednárová, Lucie (referee) ; Mašek, Vlastimil (referee)
Title: Spectroscopic study of key biomolecular interactions for therapeutic applications of modified oligonucleotides Author: Martin Kříž Department: Institute of Physics of Charles University Supervisor: Prof. RNDr. Josef Štěpánek, CSc., Institute of Physics of Charles University Abstract: This dissertation thesis is focused on study of biomolecular interactions that are crucial for therapeutic applications of modified oligonucleotides. Interactions of nucleic acids, in particular hybrid DNA: RNA duplexes with fully complementary sequences, as well as DNA: RNA duplexes with a central mismatch were studied. The molecular model was created. With this model the influence of five different chemical modifications in the DNA strand to its binding ability was studied. Structural changes were characterized by Raman spectroscopy using a precise differential and double differential spectra. These data were supplemented by thermodynamic parameters computed from melting curves obtained by UV absorption spectroscopy. Furthermore, the Raman spectroscopy was applied on study of conformation changes in the RNase L protein. These changes in the conformation occur after ligand binding, which in this case, either natural or modified short oligonucleotide. Measurement of RNase L was performed using a special experimental...

National Repository of Grey Literature : 46 records found   1 - 10nextend  jump to record:
See also: similar author names
19 ŠTĚPÁNEK, Jan
6 ŠTĚPÁNEK, Jindřich
1 Štěpánek, J.
7 Štěpánek, Jakub
19 Štěpánek, Jan
8 Štěpánek, Jaroslav
6 Štěpánek, Jindřich
4 Štěpánek, Jiří
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