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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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MINOR PHASES IN TIN-RICH HISTORICAL MATERIALS
Michalcová, A. ; Msallamová, Š. ; Fink, D. ; Friák, Martin
The historical organ pipes used to be manufactured from tin and tin-lead alloys. The tin-rich organ pipes usually contained copper as alloying elements, which make them similar to modern lead free soldering materials. The historical organ pipe materials can be used as model materials for natural ageing of soldering materials. Tin pest is a term for modification from white tin to grey tin, which leads to degradation of tin or tin-rich alloys. The influence of individual alloying elements has not been reliably described, yet. Not only on the concentration of the alloying element, but also the distribution may play the important role. In dependence on heat-treatment, the Cu can be in the Sn matrix present in these forms: i) as large intermetallic particles after casting (Cu6Sn5), ii) as solid solution after homogenization annealing and iii) as fine precipitates after ageing. The microstructure of the real historical organ-pipes material was studied and it was proven that contradictionary to the equilibrium phase diagram the Cu enriched was observed.
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Young adult Christians and their relationship to the Church
Vtípilová, Soňa ; Michalcová, Andrea (advisor) ; Eliáš, Vojtěch (referee)
VTÍPILOVÁ, S.: Young adult Christians and their relationship to the church. Prague 2008 Diploma work, Charles University in Prague, Catholic Theological Faculty. Pastoral Theology Department. Supervisor Doc. Michal Kaplánek, Th.D. Keywords: pastor leadership, young adulthood, qualitative research, young people's relationship to the church, post modernity Presented work focuses on young adult Christians and their relationship to the church. The theoretical part describes the world in which the young people live, it characterizes a group of young adults and describes their problems. The practical part gives attention to young people's expectation towards the church. The conclusions were reached using the method of qualitative sociological research, namely with the help of semi-standardized dialogues with 14 young people. The practical part contains the description of research preparative work, data processing and the subsequent interpretation. In the conclusion pastoral theological reflexion is provided.
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Stability of dispersoids in aluminium alloys at elevated temperatures.
Králík, Rostislav ; Cieslar, Miroslav (advisor) ; Michalcová, Alena (referee)
Hliníková slitina AA8079 připravena plynulým odléváním mezi válce je běžně používána pro výrobu tenké potravinářské fólie. Vzhledem k použité metodě odlévání a složení slitiny je struktura litého materiálu značně nehomogenní a obsahuje intermetalické fáze, které se shlukují v eutektických koloniích. Litý materiál tak vyžaduje tepelné zpracování před dalšími kroky výroby. Mikrostruktura materiálu po homogenizačních žíháních na různých teplotách je rozdílná, což ovlivňuje další zpracování. Po homogenizaci je materiál válcován což způsobuje snížení tažnosti. Rekrystalizační žíhání je vyžadováno po zválcování na střední tloušťku před finálním válcování, aby byla tažnost obnovena. Chování materiálu během rekrystalizačního žíhání je ovlivněno přítomnými fázemi, jejich velikostí a rozdělením. Byl studován vliv mikrostruktury po homogenizaci na rozdílných teplotách na rekrystalizaci, byla vyhodnocena kinetika rekrystalizace a byly identifikovány dva hlavní mechanismy ovlivňující rekrystalizaci - částicemi stimulovaná nukleace a Zenerův tlak.
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Religion of Jewish population and lived Judaism during normalization era in Prague
Michalcová, Andrea ; Hošek, Pavel (advisor) ; Hájek, Matěj (referee)
The diploma thesis ,,Religion of Jewish population and lived Judaism during normalization era in Prague" first explains the historical role of the Jews since their arrival in Bohamia and Moravia till the period of the 1st Republic from political and social point of view. There are depicted features of anti- Semitism as well that has been experienced by the Jews from time immemorial. The part dedicated to the Bohemia and Moravia Protectorate era is mainly built on testimony of those people who had experienced the Holocaust and became victims of extraordinary crime typical of its specific conception, execution and extent. The next chapter deals with the Jews ' return from concentration camps, Liberation Armies and there is not only literary evidence but direct interviews with respondents and survivors as well. This paper describes the way to Jewish religious life, traditions and customs recovery in our country. It also touches political trials in the 1950s ' that demonstrated to be strictly antisemitic. The following 1960s ' showed the era of oficial political strategy reassesment, Jewish matters became legitimate topics. The chapter dedicated to Jewish situation in normalization era demonstrates what then legal system brought to the whole society and its impact on Jewish inhabitans. What was enough to accuse...
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Sport and its Place in Christian Life
Šafářová, Světlana ; Kozel, Karel (advisor) ; Michalcová, Andrea (referee)
Bc thesis SPORT AND ITS PLACE IN CHRISTIAN LIFE wants to unveil a man as the whole image of the God. We have been living with the hope of salvation and we will be saved as the whole - our body, soul and spirit. Spiritual dimension of the body is based on the faith of its ressurection. The body needs the same care, attention, creativity and gratitude to the Creator as the soul and spirit do. The sport is one of the way to the care of the body. This thesis wants not only critically evaluate the place of the sport and activity of the body in Christian life but also to find its blind alleyways and risks. It also deals with the question how significant the integration of regular sport activities into the curriculum of teological faculties can be in additon to the intelectual and spiritual formation. KEY WORDS sport, physical exercise, play, Christian life, body
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Pastoral aspects of Baptism in the current debate in the German speaking sphere..
Kolářová Takácsová, Kornélia ; Filipi, Pavel (advisor) ; Michalcová, Andrea (referee) ; Filipi, Pavel (referee)
The thesis "Pastoral aspects of the baptism in the current discussion in the German speaking countries" analyzes critically the theological discussion since the seventies. The baptism is deprived of its closely sacramental and christological determination and is treated as an occasional service. Biographical and ritual concepts of the occasional services attribute to these acts a special theological significance that cannot be derived from Christ's commission to preach the gospel, but rather is rooted in a piety, which targets the life cycle of individuals and families. Occasional services are therefore seen as a pastoral accompaniment of man in his fault (and critical) stage of life. Its aim is to convey his emotional and cognitive stabilization and assist in re-establishing his fluctuating identity. The practice of the baptism, in this perspective, must regard ambivalent experiences of parents and provide them an appropriate religious intervention. Traditional theological contents of the baptism are markedly eliminated with regard to the situation of the distant Christians who became estranged from the reflected Christianity. Keywords Baptism, Pastoral Care, Occasional Services, Ritual, Folk Church
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Premonstratensian Education in the Czech Territory in the 19th Century
Jeřábková, Lenka ; Opatrný, Aleš (referee) ; Michalcová, Andrea (referee)
Premonstratensian Education in the Czech Territory in the 19th Century This specific study contributes to the knowledge of the Order in our territory in the course of the 19th century and it explores the activity of the Premonstratensian in the schools established by them. The topic is approached in the broader context of the education of the examined era. The study explains the characteristics of the schooling and education organisation system as well, focusing on the specific problematic of religious schooling and education from various points of view. As part of the argument, the Order of Canons Regular of Prémontré is described and an evaluation of its educational activities in the course of all the history of the Order is provided. A significant part of the study is dedicated to the Strahov Abbey and its educational facilities, especially to the schools that were restored or undertaken by the Order in the researched period. The conclusive part characterises other schools run by orders in the territories of Bohemia and Moravia.
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