Affecting structure characteristics of rotary swaged tungsten heavy alloy via variable deformation temperature

This study focuses on numerical prediction and experimental investigation of deformation behaviour of a tungsten heavy alloy prepared via powder metallurgy and subsequent cold (20 degrees C) and warm (900 degrees C) rotary swaging. Special emphasis was placed on the prediction of the effects of the applied induction heating. As shown by the results, the predicted material behaviour was in good correlation with the real experiment. The differences in the plastic flow during cold and warm swaging imparted differences in structural development and the occurrence of residual stress. Both the swaged pieces exhibited the presence of residual stress in the peripheries of W agglomerates. However, the NiCO matrix of the warm-swaged piece also exhibited the presence of residual stress, and it also featured regions with increased W content. Testing of mechanical properties revealed the ultimate tensile strength of the swaged pieces to be approximately twice as high as of the sintered piece (860 MPa compared to 1650 MPa and 1828 MPa after warm and cold swaging, respectively).Web of Science1224art. no. 420

Methods of insect body and food marking and their utilization in bees (Anthophila)

Metody zna ení p edstavují asto nezbytnou sou ást ady studií, které se zabývají biologií hmyzu. Tyto zna ící techniky mnohdy p edstavují jedinou možnost, jak získat nové a d ležité informace. V první ásti práce se zabývám individuálním zna ením, které bylo využito pro ozna ení samotá ských v el a jejich hnízd jakožto prost edku získání informací o hnízdní dynamice samic žijících na hnízdišti v agregaci. Práce ukazuje, že samice se v hnízdech m ní velmi asto a b žn u všech ty ech studovaných druh . Avšak velké procento obsazení hnízda samicí nastalo až po jeho opušt ní p edchozí majitelkou. Pouze ást ze všech hnízd na hnízdišti byla skute n usurpovaná. Pravé usurpace reprezentují tedy spíše minoritní ást pozorovaných zm n majitel v hnízdech. V ely p ekvapiv asto opouští svá hnízda a zakládají nová. Díky astému st ídání majitelek v hnízdech dochází k astým kontakt m samic na hnízdišti. Velká tolerance v el v i sob , spolu s p ekvapivou tolerancí usurpací a nízkou agresivitou, tak m že p edstavovat možnou cestu ke vzniku komunálního spole enství v el a jiných typ sociálního chování. V druhé ásti práce se potom zam uji na možnosti ozna ení potravy u v el. Efektivita využívání pylu a cukru v kolonii eusociálních v el nejsou dosud pln pochopeny. Zkoumání složitosti nutri ního toku v kolonii však vyžaduje...Marking methods represent often an essential part of many studies which target on insect biology. These marking techniques sometimes represent the only possible way to obtain new and important informations. In the first part of the thesis I deal with individual insect labeling, which was used for marking of solitary bees and their nests as a tool of obtaining informations about nesting bee dynamics in aggregation. Our study show that nest owner replacements are very common in all four species. However, a large percentage of the nests were abandoned by the female owners before owner change. Only a part of all the nests were trully usurped on the nesting site. The true usurpations thus represent rather minor part of observed nest owner replacement situations. The bees surprisingly often abandon their nests and found the new ones. The frequent contacts of the females on a nesting site occur as a result of common nest owner replacements. High tolerance of bees to each other together with tolerance of usurpations and low level of aggression may thus represent one of the possible ways towards communality and other types of social behaviour. In the second part of the thesis I focus on the possibilities of food marking in bees. Effectivity of sugar and pollen utilization are not yet fully understood in...Department of ZoologyKatedra zoologieFaculty of SciencePřírodovědecká fakult

Cyberostracism : Emotional and behavioral consequences in social media interactions

This study focuses on the effect of cyberostracism on social networking sites. Based on the temporal need-threat model of ostracism, we examined a) reflexive reactions, specifically worsened mood and threats to the four fundamental needs (i.e., belongingness, self-esteem, meaningful existence, and control), and b) reflective reactions, in the form of prosocial, antisocial, and avoidance behavior. We also focused on the role of social anxiety. Using the experimental tool Ostracism Online, we conducted an online experiment to manipulate ostracism, measure self-reported reflexive reactions, and measure reflective reactions in a newly developed cooperative financial game. The participants were 196 young Czech adults (age 18-30; 62% women). T-tests showed worsened mood and higher threat connected to all four of the fundamental needs in the reflexive stage in ostracized participants. Regression models showed that social anxiety had a small effect on reflexive reactions, but it did not moderate the effect of ostracism. The type of threatened need and social anxiety did not predict a reflective reaction. The only significant predictor of antisocial response was experienced ostracism. Even a mild form of ostracism such as the lack of reactions by strangers to a shared post can lead to negative emotional and behavioral consequences

Bullied Online but Not Telling Anyone : What Are the Reasons for Not Disclosing Cybervictimization?

Although telling an adult can be effective at ending bullying, not all bullied children tell someone about their victimization. The aim of the current study was to examine: 1) if being bullied online and not telling anyone was associated with the perceived intensity and harm experienced from being bullied, 2) the reasons for not telling anyone, and 3) if these reasons were related to the level of harm experienced from being bullied. The data used in this study consisted of responses from 451 Czech adolescents aged 12–18 who had been cyberbullied. The results showed that more boys (47%) than girls (19%) did not tell anyone about being bullied online. There was an association between experienced harm and cybervictimization disclosure; 42% of adolescents with little experience of harm did not tell anyone about it, which was more often than the case for those adolescents with a medium level of harm (19%), and those with intense harm (19%). The reasons for not telling differed among groups, where intensely harmed adolescents more often reported that they did not trust anyone and were afraid of making the situation worse and respondents with medium harm reported to a greater extent not having anyone who could help them. The most common answer for adolescents with a low experience of harm was that they did not tell anyone because they thought they would manage on their own (54%)

Finite element analysis of Ti-based knee-joint implant

The focus of this paper was on finite element analysis of a PROSPON oncological knee endoprosthesis. The 3D CAD knee joint model, the designed FE PROSPON prosthesis model into which was integrated, was created on the basis of Visible Human Project CT scans. Analyses of stress state and contact pressures were performed in the kneebending position within 15,4° - 69,4° hip joint flection range. The results showed that the maximum achieved stress did not exceed the yield strength (90 MPa) of the material. The results of the stress state were in accordance with the distribution of contact pressure.Web of Science54469469

Analysis of deformation behaviour and residual stress in rotary swaged Cu/Al clad composite wires

Both copper and aluminum are widely applicable throughout a variety of industrial and commercial branches, however, joining them in a composite provides the possibility of combining all their advantageous properties in one material. This study investigates uniquely sequenced copper-aluminum clad composite wires, fabricated via rotary swaging technology. The composites were processed at 20 degrees C and 250 degrees C to a diameter of 5 mm. Structural observations and the determination of residual stress within both elements of the swaged wires were performed via electron microscopy; the experimental results were correlated with numerical predictions. As shown in the results, both the applied swaging force and temperature affected the plastic flow, which had a direct influence on residual stress and texture development; the Al-sheath elements exhibited ideal rolling textures, whereas the Cu-wires elements featured ideal shear texture orientation. The grains within both the Al-sheath elements of the 5 mm composite wire were refined down to sub-micron size. Structural restoration also had a positive influence on residual stress.Web of Science1221art. no. 346

Converting Insulin-like Growth Factors 1 and 2 into High-Affinity Ligands for Insulin Receptor Isoform A by the Introduction of an Evolutionarily Divergent Mutation

Insulin-like growth factors 1 and 2 (IGF-1 and -2, respectively) are protein hormones involved not only in normal growth and development but also in life span regulation and cancer. They exert their functions mainly through the IGF-1R or by binding to isoform A of the insulin receptor (IR-A). The development of IGF-1 and IGF-2 antagonists is of great clinical interest. Mutations of A4 and A8 sites of human insulin lead to disproportionate effects on hormone IR binding and activation. Here, we systematically modified IGF-1 sites 45, 46, and 49 and IGF-2 sites 45 and 48, which correspond, or are close, to insulin sites A4 and A8. The IGF-1R and IR-A binding and autophosphorylation potencies of these analogues were characterized. They retained the main IGF-1R-related properties, but the hormones with His49 in IGF-1 and His48 in IGF-2 showed significantly higher affinities for IR-A and for IR-B, being the strongest IGF-1- and IGF-2-like binders of these receptors ever reported. All analogues activated IR-A and IGF-1R without major discrepancies in their binding affinities. This study revealed that IR-A and IGF-1R contain specific sites, likely parts of their so-called sites 2′, which can interact differently with specifically modified IGF analogues. Moreover, a clear importance of IGF-2 site 44 for effective hormone folding was also observed. These findings may facilitate novel and rational engineering of new hormone analogues for IR-A and IGF-1R studies and for potential medical applications

Insulin-like Growth Factor 1 Analogs Clicked in the C Domain : Chemical Synthesis and Biological Activities

Human insulin-like growth factor 1 (IGF-1) is a 70 amino acid protein hormone, with key impact on growth, development, and lifespan. The physiological and clinical importance of IGF-1 prompted challenging chemical and biological trials toward the development of its analogs as molecular tools for the IGF-1 receptor (IGF1-R) studies and as new therapeutics. Here, we report a new method for the total chemical synthesis of IGF-1 analogs, which entails the solid-phase synthesis of two IGF-1 precursor chains that is followed by the CuI-catalyzed azide-alkyne cycloaddition ligation and by biomimetic formation of a native pattern of disulfides. The connection of the two IGF-1 precursor chains by the triazole-containing moieties, and variation of its neighboring sequences (Arg36 and Arg37), was tolerated in IGF-1R binding and its activation. These new synthetic IGF-1 analogs are unique examples of disulfide bonds' rich proteins with intra main-chain triazole links. The methodology reported here also presents a convenient synthetic platform for the design and production of new analogs of this important human hormone with non-standard protein modifications

The Influence of the Human on Nature in a Historical Context with an Educational Hike - Týnec nad Sázavou

The principal goal of this diploma thesis is to study the impact of human's activity on the nature in the region of Týnec nad Sázavou from the beginning of the human's colonization until today. This impact was not only negative, we can find positive influences, too. The work is divided into six general chapters that describe always one particular problem. Purposes and hypothesis of the diploma thesis are introduced in the first chapter, which is a prologue of the present work. History of Týnec nad Sázavou and of the country around is described in the second chapter and provides an image of the city's industrial and structural development. Research work of the influence of human's activity on the nature during the history is presented in the third chapter. Several domains were studied: geology, relief and country sight, climatic effects, soil, fauna and flora in Týnec and surroundings, nature protection, forests, river Sázava, housing, industry, traffic and other networks. Situation in the history, present condition of the nature, author's evaluation and suggestion for regeneration are described for every field of study. Chapter four introduces theory of didactical walk and his benefits for children education. Chapter five details some suggestions of educative walks in the region of Týnec nad Sázavou. Each..

Professional Profile of the Educator Working with Children and Young People in their Free Time

The degree work outlines the professional profile of the educator working with children and young people in their free time. The introductory chapter explains the basic concepts and focuses on the characteristics of the theory of teacher´s profession, personality, values and key competences. The historical development describes education, and the concept of educator in its historical context. The next chapter focuses on the professional possibilities of the free-time educator. His or her educational activities are defined by the brief survey of institutions and facilities where children and young people spend their free time. The final part concentrates on the overall evaluation of the free-time educator. The professional profile contains certain individual qualities as well as theoretical and practical abilities