National Repository of Grey Literature 39 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Dynamics of hydrogen bonded networks viewed by NMR spectroscopy
Dvořák, Petr ; Lang, Jan (advisor) ; Hanyková, Lenka (referee) ; Hritz, Jozef (referee)
Title: Dynamics of hydrogen bonded networks viewed by NMR spectroscopy Author: Petr Dvořák Department: Department of Low Temperature Physics Supervisor: doc. RNDr. Jan Lang, Ph.D., Department of Low Temperature Physics Abstract: This work describes especially experimental studies of dynamic processes in common polar solvents such as water and ethanol. The nuclear magnetic reso- nance (NMR) technique was used - primarily measurements of NMR relaxa- tions and measurements of self-diffusion coefficients using NMR. Three main topics were addressed. The first one deals with chemical exchange in mixtures of light and heavy water. Within this topic, a methodology for the preparation of ultra-pure samples was developed and a suitable method for suppressing radiation damping was proposed. Then the final samples were prepared, and the relaxation data were measured. Three models of chemical exchange were discussed. The second topic deals with correction of the Stokes-Einstein rela- tion so that it can also be used for determination hydrodynamic radii of small molecules and clusters. This correction was made by comparing the measured diffusion coefficients of the model molecules with the calculated diffusion coef- ficients using hydrodynamic simulations. The third topic deals with the relax- ivity of magnetic...
Supramolecular complexes of oxoporphyrinogens with organic molecules
Březina, Václav ; Hanyková, Lenka (advisor) ; Mojzeš, Peter (referee) ; Tošner, Zdeněk (referee)
Title: Supramolecular complexes of oxoporphyrinogens with organic molecules Author: Václav Březina Department: Department of Macromolecular Physics Supervisor: doc. RNDr. Lenka Hanyková, Dr., Department of Macromolecular Physics Abstract: Oxoporphyrinogens are flat macrocyclic molecules possessing binding and protonation sites, and capable of light absorption in the visible region. These properties are prerequisites for a colori- metric molecular sensor, i.e. a specific detector of other molecules in the sample. In this work, we studied chromic properties of three oxoporphyrinogens, OxP and its partially (Bz2OxP) and fully (Bz4OxP) N-benzylated derivatives. Their colorimetric response to organic acids is caused by protonation and subsequent formation of supramolecular host-guest complex. We have shown that colorimetric sensitivity is highest for OxP and gradually weakens for Bz2OxP and Bz4OxP since the N-benzylation blocks the central binding sites, decreasing binding affinity of the ox- oporphyrinogens. Furthermore, solvatochromic response of the oxoporphyrinogens to varying solvent polarity showed similar sensitivity decrease in Bz2OxP and Bz4OxP. The chromic and binding properties were studied by UV/vis and NMR spectroscopy, host-guest binding models were applied to describe the formation of...
Measurement of transverse relaxation using spin echo methods
Škoch, Antonín ; Tošner, Zdeněk (advisor) ; Hanyková, Lenka (referee)
Title: Measurement of transverse relaxation using spin echo methods Author: MUDr. Antonin Skoch, Ph.D. Department: Department of Low Temperature Physics Supervisor: RNDr. Zdenek ToSner, Ph.D. NMR laboratory, of Faculty of science, Charles University in Prague Supervisor's e-mail address: tosner(o)karlov.mff.cuni.cz Abstract: The study of TI relaxation in systems with homonuclear J-coupling is complicated by modulation in the relaxation curve. This J-modulation can be removed when CPMG sequence is used and the period of repetition of refocusing pulse Tfulfils a condition r « * ( 1 ) Ai' where Av is the frequency difference of coupled nuclei. However, the condition (I) cannot be in practice always fulfilled. The aim of this work was to investigate J-modulation and relaxation behaviour of homonuclear J-coupled system in various parameters of CPMG sequence. Simulations based on numerical solution of Liouville-von Neumann equation and Redfield theory were performed. Relaxation curves of Chh group of citrate were measured on high-resolution NMR spectrometer. It was found that the suppression of J-modulation can be achieved also for T longer than required by the condition (1) providing that the refocusing angle in CPMG for both J-coupling partners 9^180ř. The simulations yielded conditions for T when J-modulation...
The Study of Dynamic Behaviour and Interactions During the Temperature-Induced Phase Separation in Polymer Solutions
Kouřilová, Hana ; Hanyková, Lenka (advisor) ; Štěpánková, Helena (referee) ; Dušková - Smrčková, Miroslava (referee)
Title: The Study of Dynamic Behaviour and Interactions During the Tempera- ture-Induced Phase Separation in Polymer Solutions Author: Hana Kouřilová Department / Institute: Charles University in Prague, Faculty of Mathemat- ics and Physics, Department of Macromolecular Physics Supervisor of the doctoral thesis: doc. RNDr. Lenka Hanyková, Dr. Abstract: 1 H and 13 C high-resolution NMR spectroscopies were used for the phase separation investigation in three types of polymer solutions: i) poly(N -isopropylmethacrylamide)/D2O/ethanol with or without negatively charged comonomer sodium methacrylate, ii) random copolymers poly(N -isopro- pylmethacrylamide-co-acrylamide) in D2O, D2O/ethanol and D2O/acetone and iii) D2O solutions of polymer mixtures poly(N -isopropylmethacrylamide)/poly(N - vinylcaprolactam). For i) cononsolvency effect and influence of temperature on the phase separation was studied. Differences between mesoglobules formed as a consequence of cononsolvency effect and of temperature were found. While inside the cononsolvency-induced mesoglobules no bound ethanol molecules were detect- ed, in the mesoglobules formed by the effect of temperature ethanol molecules were present. The charge introduced into the polymer chains strenghtens polymer- solvent interactions. For ii) mesoglobules were found to be...
Study of dynamical behaviour of H2O/D2O mixtures by NMR relaxation
Dvořák, Petr ; Lang, Jan (advisor) ; Hanyková, Lenka (referee)
Title: Study of dynamical behavior of H2O/D2O mixtures by NMR relaxation Author: Petr Dvořák Department: Department of Low Temperature Physics Supervisor: doc. RNDr. Jan Lang, Ph.D., Department of Low Temperature Physics Abstract: The subject of this diploma thesis is the chemical exchange in the mixture of light and heavy water, which was studied by methods of high resolution NMR. The first part of this thesis concerns methodology of sample preparation and methodology of measurement of relaxation times of mixture of light and heavy wa- ter. Experimental complications with elution of ions from tube glass, degassing of samples, radiation damping and sample heating by radio-frequency pulses were solved there. In the second part of this thesis the relaxation parameters of chemical exchange of selected sample at various temperatures were measured. Interpretations of experimental data (ionization, molecular clusters and isotopic equilibrium) was suggested. Keywords: NMR, relaxation, water, dynamics, chemical exchange
Spectroscopic Study of the Dynamical Behavior and Interactions in Supramolecular and Macromolecular Systems
Radecki, Marek ; Hanyková, Lenka (advisor) ; Matějka, Libor (referee) ; Kronek, Juraj (referee)
Title: Spectroscopic Study of the Dynamical Behavior and Interactions in Supramolecular and Macromolecular Systems Author: Marek Radecki Department: Department of Macromolecular Physics Supervisor: Doc. RNDr. Lenka Hanyková, Dr., Department of Macromolecular Physics Abstract: In this thesis, the temperature-induced phase transition in liner polymer solutins and hydrogels of semi-interpenetrating (SIPNs) and interpenetrating (IPNs) polymer networks was studied with respect to various composition, network architecture and procedure. Thermoresponsive linear polymers based on poly(vinyl methyl ether) (PVME) in water and with terc-buthyl based additives, IPNs of polyacrylamide (PAAm), poly(N -isopropylacrylamide) (PNIPAm), poly(N - vinylcaprolactam) (PVCL) and IPNs and SIPNs of poly(N,N -diethylacrylamide) (PDEAAm) were investigated by the methods of nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), optical microscopy (OM) and swelling experiments. The effect of polymer concentration and presence of additives on the dynamics during the phase separation as well as interactions between the water and the polymer in aqueous solutions of PVME and PVME/additives were established. The increasing content of hydrophilic PAAm component in SIPNs and IPNs shifts the transition toward...
Self-Assembly in Mixture of Surfactants and Stimuli-Responsive Polymers with Complex Architecture
Bogomolova, Anna ; Filippov, Sergej (advisor) ; Štěpánek, Miroslav (referee) ; Hanyková, Lenka (referee)
Title: Self-assembly in mixture of surfactants and stimuli-responsive polymers with complex architecture Author: Anna Bogomolova Department: Physical and Macromolecular Chemistry Supervisor: PhD. Sergey K. Filippov, IMC AS CR, v.v.i. Supervisor's e-mail address: filippov@imc.cas.cz Abstract: The issue of construction of complex multi-block copolymers is currently one of the most researched areas. It became a logic consequence of the continuous development in polymer chemistry. Nowadays, a great interest is attracted to multi- responsive block copolymers. As a rule, they consist of hydrophilic, hydrophobic and responsive blocks. That responsive block can be either thermo-sensitive or pH-sensitive as well as sensitive to some other external stimuli. In the present work, we will try to cover topic of stimuli-responsive block copolymers and their interactions with different types of surfactants. Understanding of polymer/surfactant interactions can be a crucial step for future modeling of drug/polymer or protein(DNA)/surfactant interactions. There is a great interest in the investigation of polymer-surfactant interactions. However, while the homopolymer-surfactant interactions are characterized well enough, the same interactions for block copolymers are poorly described. The main development in the latter topic...

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