National Repository of Grey Literature 52 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Peripheral functionalization of polydentate Schiff ligands for preparation of biologically active Fe(III) and Co(III) complexes
Kotásková, Lucie ; Antal, Peter (referee) ; Nemec, Ivan (advisor)
Diploma thesis deals with preparation of peripherally functionalized polydentate Schiff ligands, suitable for metal coordination, such as Fe(III) or Co(III). The compounds, formed by this functionalization using organic molecule or stable organic radical, provide coordination site for another central atom. The compounds were synthesized for their potential biological activity. The organic ligands series was prepared, and these ligands were submitted to coordination reactions with selected transition metals. The prepared compounds were characterized by nuclear magnetic resonance, mass spectrometry, electron paramagnetic resonance and X-ray structure analysis.
Algorithms for design and analysis of membrane structures
Lang, Rostislav ; Krejsa,, Martin (referee) ; Kytýr, Jiří (referee) ; Němec, Ivan (advisor)
The present thesis deals with membrane structures, focusing on the description of both the inherent physical necessitates which has to be dealt and the algorithms used when developing the FEM software. After introducing physical basis of the individual design and analysis steps, the specific issues associated with these calculation procedures as well as the particular solution processes are described. The first chapter deals with the form finding analysis, which is inherently associated with designing tensile structures. The equilibrium shape is derived from the requirement for the resulting prestress, given boundary conditions and applied external load. However, this process is also generally dealing with a complex task of searching for the equilibrium itself. Therefore, necessary stabilization techniques are an inherent part of the calculation procedures. The selected methods as well as the proposed technique specialized for the calculation of conical membranes are presented. In addition to the given thesis scope, the proposal of an algorithm for dealing with optimizing the shapes of arches and shells is described. In the chapter about the structural analysis, the main focus is given to the phenomenon of membranes wrinkling. This sudden loss of stability, when the compression occurs, strongly affects the structural response. The proposed algorithm is presented, which is modularly applicable to both the elastic and inelastic materials as described in detail. The chapter dealing with the cutting pattern generation process presents the proposal of the selected combination of two existing solution methods. This algorithms sequence focuses on reaching the optimum combination of the calculation speed, generality and precision. The individual chapters are complemented by presenting of the examples analyzed by using the described algorithms, which demonstrate the individual physical or implementation issues and the associated solution procedures.
New pathways to plasmonic nanoparticle assembling into 2D and 3D hybrid active systems for SERS of graphene and SERS, SERRS and GERS + SERS of aromatic molecules
Gajdošová, Veronika ; Vlčková, Blanka (advisor) ; Němec, Ivan (referee) ; Michl, Martin (referee)
In the first part of the Thesis, a new type of active system for SERS and SERRS of hydrophobic molecules, namely a 3-dimensional (3D) nanosponge aggregate with incorporated hydrophobic molecules has been developed, and tested by fullerene C60 and hydrophobic free- base tetraphenylporfine (H2TPP). The SERS and SERRS (surface enhanced /resonance/ Raman scattering) limits of detection (LODs) of C60 at four excitation wavelengths spanning the visible spectral region were found to be by one order of magnitude lower than in the reference system, which mimics the previously reported ways of utilization of Ag nanosponges as substrates for SERS and SERRS. The superiority of the newly developed sample is attributed to the efficient localization of the hydrophobic molecules into hot spots in 2D fractal aggregates of Ag nanoparticles (NPs). Diprotonation of H2TPP during the procedure using HCl as the preaggregation agent has been eliminated by employment of NaCl. On the other hand, investigation of the mechanism of H2TPP protonation during the former preparation procedure opened a possibility to employ Ag nanosponge aggregate as nanoreactor. In the second part of the Thesis, 2D assemblies of AgNPs were found to be better substrates for SERS of single layer graphene (SLG) than the 3D ones. In particular, the 2D...
Preparation and study of novel crystalline materials for nonlinear optics based on nitrogen-containing heterocycles
Kloda, Matouš ; Němec, Ivan (advisor) ; Schwendt, Peter (referee) ; Holubová, Jana (referee)
The presented Ph.D. thesis is aimed at the preparation and characterisation of novel crystalline materials with application potential in nonlinear optics (NLO). The main goal was preparation of crystalline salts and adducts (cocrystals) of selected nitrogen-containing heterocycles with a range of organic and inorganic acids. Based on previous study and quantum- chemical calculations, the following starting heterocycles were selected: 2-aminopyrimidine, 4-aminopyrimidine, 5-aminopyrimidine, 3-amino-1,2,4-triazine and 3-amino-5,6-dimethyl- 1,2,4-triazine. The prepared materials were characterised mainly by X-ray diffraction and vibrational spectroscopy and the interpretation of the vibrational spectra was based on quantum-chemical calculations. The systems based on aminopyrimidines were the first field of study in presented thesis. The thesis represents a finalisation of our previous study focused on inorganic salts and cocrystal in the case of 2-aminopyrimidine. The characterisation of a pair of cocrystals with boric acid was accomplished. The 12 new salts and adducts were prepared and characterised in the case of 4-aminopyrimidine and only one crystalline product - adduct with succinic acid - was obtained in the case of 5-aminopyrimidine. The systems based on 3-amino-1,2,4-triazine and its...
The exploitation of parallelization to numerical solutions regarding problems in nonlinear dynamics
Rek, Václav ; Krejsa,, Martin (referee) ; Vala, Jiří (referee) ; Němec, Ivan (advisor)
The main aim of this thesis is the exploration of the potential use of the parallelism of numerical computations in the field of nonlinear dynamics. In the last decade the dramatic onset of multicore and multi-processor systems in combination with the possibilities which now provide modern computer networks has risen. The complexity and size of the investigated models are constantly increasing due to the high computational complexity of computational tasks in dynamics and statics of structures, mainly because of the nonlinear character of the solved models. Any possibility to speed up such calculation procedures is more than desirable. This is a relatively new branch of science, therefore specific algorithms and parallel implementation are still in the stage of research and development which is attributed to the latest advances in computer hardware, which is growing rapidly. More questions are raised on how best to utilize the available computing power. The proposed parallel model is based on the explicit form of the finite element method, which naturaly provides the possibility of efficient parallelization. The possibilities of multicore processors, as well as parallel hybrid model combining both the possibilities of multicore processors, and the form of the parallelism on a computer network are investigated. The designed approaches are then examined in addressing of the numerical analysis regarding contact/impact phenomena of shell structures.
Application of Raman spectroscopy for detection of sulfates of self-ignited coal heaps
Košek, Filip ; Jehlička, Jan (advisor) ; Němec, Ivan (referee) ; Vandenabeele, Peter (referee)
This Ph.D. thesis was focused on the application of Raman spectroscopy as the main analytical method for the characterization of neo-formed minerals, notably sulfates, from burning coal waste dumps. This environment associated with subsurface fires gives rise to a variety of uncommon and rare minerals. The specific features of these minerals (metastability, hygroscopy, mixed aggregates) causes that the mineralogical investigation is a challenging task using traditional laboratory-based techniques. Advantages such as the non-destructive nature, the sensitivity to the changes in the hydration degree of sulfates, little or none pretreatment, and the option of measurements directly in the field were the main reasons for applying this spectroscopy method. The scarce availability of spectroscopic data of most gas-vent minerals can be considered as the disadvantage. Therefore, artificial prepared samples of six anhydrous sulfates, which are rarely found in nature, were analyzed by Raman laboratory spectroscopy and a miniature a Raman spectrometer, and specific Raman features as well the differences with hydrated counterparts are shown. Laboratory investigation of two natural hydrated aluminum sulfates, alunogen and khademite, were carried out using Raman spectroscopy and other methods in order to obtain...
Synthesis and study of crystalline materials for NLO
Janatková, Tereza ; Němec, Ivan (advisor) ; Vojtíšek, Pavel (referee)
This thesis is focused on preparation and study of new compounds of chosen organic bases with potential use in nonlinear optics. 2-amino-5-nitropyrimidine, 2-amino-4-methylpyrimidine and their salts with inorganic and organic acids are compounds of the main interest. Diffraction and vibrational-spectroscopic methods of characterization were used in combination with quantum chemical calculation methods. Another aim of this thesis was preparation of new salts of chosen pyrimidine derivates with the use of methylsulphonic acid. Part of this section is devoted to completion of pyridinium methylsulphonate phase transition and nonlinear optical property studies.
Molecular crystals for NLO applications - compounds of 1H-pyrazole-carboxamidine
Kohúteková, Soňa ; Němec, Ivan (advisor) ; Šloufová, Ivana (referee)
Title: Molecular crystals for NLO applications - compounds of 1H-pyrazole-carboxamidine Author: Bc. Soňa Kohúteková Department: Department of Inorganic Chemistry Supervisor: prof. RNDr. Ivan Němec, Ph.D. Abstract: The aim of this diploma thesis is preparation and characterisation of novel compounds of 1H-pyrazole-carboxamidine in consideration of their potential application in the field of nonlinear optics. This thesis is focused on preparation of crystalline salts or adducts combining 1H-pyrazole-carboxamidine with selected inorganic and organic acids. Prepared materials were characterised mainly by the means of vibrational spectroscopy and X-ray diffraction analysis. Quantum-chemical calculations were used for a prediction of nonlinear optical properties as well as for interpretation of measured vibrational spectra. Four different approaches of calculations were used for an optimisation of computing time together with accuracy of the fit of calculated and measured spectra. Finally, measurements of second harmonic generation efficiency of two powder samples with non-centrosymmetric crystal structures were performed. Key words: NLO, vibrational spectroscopy, crystal structure, quantum-chemical calculations
Carotenoids of snow algae as biomarkers for exobiology: Raman spectroscopic perspective
Němečková, Kateřina ; Jehlička, Jan (advisor) ; Němec, Ivan (referee)
The major aim of this thesis is critical evaluation of Raman spectroscopy in the detection of carotenoids of extremophiles, namely snow algae. Extremophilic microorganisms play an important role in exobiology since they set hypothetical boundaries for the presence of life on Earth. Raman spectroscopy will be a part of two mission to Mars. Here, a laboratory Raman microspectrometer was used for the analysis of 11 samples of snow algae from different locations over the years 2002-2017. The acquired spectra were compared with HPLC/UV-VIS analysis. The results showed that the ability of Raman spectroscopy to discriminate between structurally slightly differing carotenoid pigments or several carotenoids in an admixture is limited. Contrary, HPLC/UV-VIS permitted to detect various structurally similar carotenoids (and chlorophylls). However, HPLC/UV-VIS worked with overall pigment extracts during which some structural information can be lost. Raman microspectrometer allowed analysis of cells in different life-cycle stages and thus several various spectra could be studied. Raman microspectrometer was therefore more suitable for carotenoid detection in mixtures of various life-stages than HPLC/UV-VIS. Key words carotenoids, snow algae, exobiology, habitability, biomarker, Raman spectroscopy, HPLC/UV-VIS

National Repository of Grey Literature : 52 records found   1 - 10nextend  jump to record:
See also: similar author names
4 Němec, Igor
1 Němec, Ivo
Interested in being notified about new results for this query?
Subscribe to the RSS feed.