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QUANTUM-MECHANICAL STUDY OF INTERNAL STRUCTURAL TRANSFORMATIONS IN Pb-SUPERSATURATED Pb-Sn ALLOYS
Friák, Martin ; Čípek, Petr ; Pavlů, J. ; Roupcová, Pavla ; Miháliková, Ivana ; Msallamová, Š. ; Michalcová, A.
Motivated by a decades-long controversy related to the crystal structure of Pb-supersaturated solid solutions of Pb in Sn, we have performed a quantum-mechanical study of these materials. Focusing on both body-centred-tetragonal beta-Sn and simple-hexagonal gamma-Sn structures, we have computed properties of two alloys with the chemical composition Pb5Sn11, i.e. 31.25 at. % Pb, which is close to the composition of the experimentally found alloy (30 at. % Pb). The 16-atom computational supercells were designed as multiples of the elemental beta- and gamma-Sn unit cells, where the Pb atoms were distributed according to the special quasi-random structure (SQS) concept. Full structural relaxations of both beta- and gamma-phase-based alloys resulted in very significant re-arrangements into structures which do not exhibit any apparent structural features typical for the original alloys, and are, therefore, difficult to classify. The formation energies of the beta- and gamma-phase-originating equilibrium phases are 50 meV/atom and 53 meV/atom, respectively. Therefore, they are not stable with respect to the decomposition into the elemental lead and tin. Moreover, our calculations of elastic constants of both phases revealed that they are close to mechanical instability. Our results indicate that the studied Pb-supersaturated Pb-Sn solid solutions may be prone to structural instability, transformations into different phases and decomposition. Our findings may contribute into the identification of the reason why the subsequent experimental studies did not reproduce the initial published data.
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A special educator and a psychologist in every school? Institutionalisation of support teaching positions in primary schools
Panák, Petr ; Mouralová, Magdalena (advisor) ; Černý, Jakub (referee)
The thesis focuses on the policy of institutionalisation of support teaching positions, which extends school special educators and school psychologists to primary schools and tries to ensure the stability of professions of the support teaching positions. The thesis focuses on the piloting of institutionalisation in small primary schools with 20-179 pupils, where schools are provided with support teaching positions by pedagogical-psychological counselling centres. The aim is to describe the functioning of the institutionalisation model and to understand how it is perceived by school special educators, school psychologists and heads of pedagogical- psychological counselling centres. The thesis is framed by two theoretical concepts: the street- level bureaucracy and the theory of accountability. The thesis uses various data sources, from questionnaires to interviews, public policy documents, and administrative data. Based on these data, the thesis concluded that it has not yet been possible to ensure a sufficient expansion of support teaching positions into schools, mainly due to the lack of qualified staff nor the professional stability of support teaching positions, as these do not have the certainty of continuation of institutionalisation in 2025. At the same time, the role of pedagogical- psychological...
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Synthesis and characterization of neurosteroid prodrugs
Vaculčíková, Adéla ; Kudová, Eva (advisor) ; Urban, Milan (referee)
This bachelor thesis explores various methods for neurosteroid prodrugs synthesis. The thesis aims to optimize the physicochemical and metabolic properties of neurosteroids to facilitate their transport across membranes, in particular the permeability of the blood-brain barrier. Neurosteroids are endogenous compounds that are synthesized in the brain from cholesterol. Their characteristic functional group is the hydroxyl substituent at the C-3 position. This substituent is a significant structural feature for biological activity (e.g., allosteric modulation of γ-aminobutyric acid receptors). However, the C-3 hydroxyl group can be easily metabolized. Moreover, the free hydroxyl group in the neurosteroid molecule increases its hydrophilicity which can limit the transport across the membrane. Therefore, within this thesis: 1) neurosteroids with different skeletons and 2) analogs of neurosteroids with ester group in C-3 position, will be prepared. The C-3 substituents have been selected based on literature research identifying ester prodrugs targeting improved blood-brain barrier permeability. For newly prepared substances, their metabolic and physicochemical properties, such as solubility, permeability, and metabolic stability will be determined within the collaboration at the Institute of Organic...
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Impact of warming on soil organic carbon
Štecová, Michaela ; Vindušková, Olga (advisor) ; Jílková, Veronika (referee)
Climate change is the main cause of rising global temperatures around the world. Carbon sequestration in terrestrial ecosystems is considered one of the main tools for climate change mitigation, but current estimates of sequestration potential do not include the impacts of future climate change. The aim of this thesis is to summarize our current knowledge on the response of soil organic carbon to warming, alone as well as in combination with other drivers of climate change. A complementary aim is to compare the different methods used to study the impact of warming on soiIncreased temperature causes significant losses of soil carbon, but no consistent effect has been observed in combination with other aspects of climate change. Research suggests that carbon losses depend on the stability of soil fractions, with warming leading to greater decreases in particulate organic matter (POM). The combination of warming with rising CO2 concentration has led to an overall increase in soil carbon, although losses have been observed in combination with drought. When studying the effects of warming on soil carbon stocks, selecting the appropriate method is crucial. Active methods offer precise control but are more expensive and can impact soil biota, whereas passive methods are cheaper but require more time....
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Benchmark of the Computational Tools for the Prediction of the Effect of Mutations on Protein Stability
Berezný, Matej ; Martínek, Tomáš (referee) ; Musil, Miloš (advisor)
Návrh proteínov vyžaduje informáciu o tom ako mutácie ovplyvňujú celkovú stabilitu proteinu. Pre tento prípad existuje mnoho verejne dostupných nástrojov avšak ich kolektívne používanie či porovnávanie je veľmi pracné. Presne pre tento prípad som vyvinul BenchStab; konzolovú aplikáciu/Python knižnicu navrhnutú pre rýchlu a priamočiaru manipuláciu s 18 prediktormi, umožňujúc hromadné získavanie mutačných výsledkov. Zároveň som vytvoril novú unikátnu dátovú sadu, získanú z FireProtDB. Tento dataset som použil na porovnanie 24 rôznych predikčných metód pomocou rôznych metrík.
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Models for Predicting Business Financial Performance
Vakhrushev, Dmitrii ; Oulehla, Jiří (referee) ; Luňáček, Jiří (advisor)
The thesis focuses on models for predicting the financial performance of the ALZA company, where it focused on emphasizing the strong financial performance and stability of the company. Key factors contributing to ALZA's success will be mentioned, such as consistent revenues, profits, effective cost management and investment in innovation. In addition, the work would also focus on potential strategies for further growth, such as exploring new markets, strengthening online sales, diversifying product offerings, and strengthening relationships with customers and suppliers. Emphasizing the importance of continuous innovation, market monitoring and strategic investment will demonstrate ALZA's readiness for future success and market expansion.Using financial data for the period 2017 to 2022, market trends and industry benchmarks, accurate predictions can be made regarding ALZA's future financial results. Implementing advanced modelling techniques and incorporating different scenarios can provide valuable insights for strategic decision-making.
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Optimization of Combined Chitosan Particles and their Characterization for Cosmetic use
Mrůzková, Barbora ; Dzurická, Lucia (referee) ; Bendová, Agáta (advisor)
The bachelor thesis focused on optimizing preparation and characterization of chitosan coated liposomes with selected active substances and their use for cosmetic applications. The theoretical part of the thesis describes natural substances, their effect on the skin, encapsulation methods, and the preparation and use of liposomes and chitosomes. In the experimental part, the optimization of the preparation of liposomes and chitosomes and their subsequent characterization by measuring particle size, polydispersity index, zeta potential, encapsulation efficiency and gradual release of active substances were performed. The selected active substances in this work were vitamin C, -carotene, caffeine and vitamin E. From the data obtained, the method of adding liposomes dropwise into the 2% chitosan with a short mixing time and ultrasonication for 1 minute was selected as the most suitable method for the preparation of chitosomes usable in cosmetics. Furthermore, the encapsulation efficiency of the particles and the antioxidant capacity of vitamin C, -carotene, caffeine and vitamin E were compared. The best antioxidant properties were determined for vitamins C and E; therefore, the gradual release of chitosomes with these active substances was subsequently measured in an environment simulating cosmetics. At the end of the work, cosmetic emulsions and gels containing selected chitosomes were prepared and tested on the skin by determining changes in desquamation.
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Center for seniors in Brno-Medlánky
Otépka, Petr ; Klimecký, Martin (referee) ; Gerö, Jiří (advisor)
The architectural study for the elderly home follows on the urban-architectural study conducted in the previous semester as a part of the NGA056 – Specialised Studio course. The study resulted in a compact urban development with mix of functions. It includes not only housing, commerce, public buildings, the church, the sport hall and transport facilities, but also a block of centre for elderly. The architectural study is focused on creating a complex centre with good supply of services, amenities, privacy and, most importantly, quality spaces. The design is based on the concept of compactness. All pavilions which are full of spatial and operational requirements form a block and inner courtyard. The inner courtyard is situated above the underground parking, and it is adjacent to a park, connected to it by a ‘neck’. The park opens to the southwest and its borders are defined by the centre on the east and apartment building for elderly on north side. On the side which faces the centre of the new district, the block turns on its ground floor, accommodating a café, entrances and other services. It facilitates connection with the community, together with park on the opposite side. The proposal presents a contemporary perspective on housing for the elderly in our society. The spaces try to have their own identity, with which residents or clients can identify and accept a room or apartment as their home, rather than just a final stop on their life’s journey.
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The applications of differential equations in the temperature regulation
Horáček, Jan ; Švarc, Ivan (referee) ; Dosoudilová, Monika (advisor)
This bachelor's thesis deals with the importance of differential equations in control theory. The review section is devoted to a reminder of the mathematical apparatus of linear differential equations and the methods of solving them, including the characteristic equation and the Laplace transform. Furthermore, the research part deals with control, transfer function and stability. The final section is devoted to the solution of a real room temperature change problem including software verification.
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Stability of non-linear mechanical systems
Hrabec, Martin ; Řehák, Pavel (referee) ; Opluštil, Zdeněk (advisor)
This thesis deals with stability analysis of non-linear mechanical systems. Firstly there are introduced basic concepts of non-linear dynamical systems and stability. The theory of deterministic chaos and Lypunov exponents is described next. Numerical calculations focused on indication of chaotic behaviour are presented as well.
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