Dislocation relaxation and alloy softening of bcc alloys

Recently, low-frequency internal friction measurements on a series of Fe–Cr alloys by Konstantinovi? and Terentyev [M.J. Konstantinovi? and D. Terentyev, Mater. Sci. Eng. A 521–522 (2009) p.106] have demonstrated that increasing Cr concentrations lead to an increase in the strength of the β-relaxation at the cost of the γ-relaxation (Chambers’ notation). In the same concentration and temperature regime, the alloys show alloy softening. It is argued that both phenomena are due to the same process, namely the influence of foreign atoms on the transformation of the cores of a ₀?1 1 1?/2 screw dislocations from their low-temperature configuration, capable of forming kink pairs on {1 1 0} planes, to their high-temperature configuration with kink-pair generation on {2 1 1} planes.     

Structural investigations on Nd-doped silica nanocomposites: effect of sintering temperature and dopant concentration

Neodymium-doped silica nanocomposites were prepared from an acid-catalysed sol–gel solution followed by heat treatment. The structural and microstructural properties of the prepared samples as a function of sintering temperature and Nd concentration are reported. Fourier transform infrared spectra show that phase separation occurs during heat treatment. The presence of Nd₂O₃ and α-Nd₂Si₂O₇ phases in the samples was established by X-ray diffraction (XRD), and transmission electron microscopy (TEM) micrographs revealed the microstructure of the nanocomposites. From XRD patterns, the crystallite size was determined using the Debye–Scherrer formula, while the particle size was estimated from TEM micrographs. The results suggest that sintering at high temperature enhances the crystallinity and density of Nd₂O₃–SiO₂ nanocomposites, while the high concentration of neodymium prevents the crystallization of SiO₂.     

Room temperature ferromagnetism and photoluminescence of nanocrystalline Zn1 − xCoxO thin films prepared by sol–gel MOD

Zn_1???xCo_xO (ZC) [x?=?0, 1, 3, 5, 7 and 9?mol%] thin films were prepared by sol–gel combined metallo-organic decomposition method. The films were deposited on the Si substrate with spin-coating technique and annealed at 600?°C for 3?h. X-ray diffraction pattern shows the formation hexagonal wurtzite phase and distortion (c/a) decreases with increasing Co concentration in ZnO. The average grain size is measured using Scherer relation. Atomic force microscopy is used to confirm the formation of nanograins resulted by the use of polyethylene glycol as surfactant. The photoluminescence was recorded by using He-Cd laser of excitation wavelength 325?nm in wavelength region of 350–650?nm which exhibits some influence of Co doping on the multiplication of defects such as O vacancies, Zn interstitials and grain boundary defects. All thin films show room temperature ferromagnetism except pure ZnO which is diamagnetic and 9?mol% of Co shows paramagnetism. This behaviour is interpreted as due to fluctuations in the magnetic ordering, depending on grain size and site location in grain boundaries or oxygen vacancies.     

Interactions of persistent slip bands with a grain boundary on the common primary slip plane in a copper bicrystal

In this letter, the dislocation patterns on the common primary slip plane in a fatigued \[1-34]-\[182-7] copper bicrystal with a Sigma=19b grain boundary (GB) have been investigated using the electron channelling contrast technique in a scanning electron microscope. The results show that the two-phase dislocation structure, such as veins and persistent slip band (PSB) walls, embedded within veins, can be clearly seen on the common primary slip plane. In particular, the interactions of PSBs with the GB are clearly revealed. It is found that there are three kinds of interaction mode between the GB and the dislocations during cyclic deformation, and those are discussed. It is suggested that the dislocations carried by PSBs cannot transfer through the GB continuously even though the bicrystal has a common primary slip plane and its surface slip bands are continuous across the GB.     

The key role of nanoscale surface facets on the mechanical strength and failure of wurtzite and periodically twinned zinc-blende nanowires

Using molecular dynamics, we study the role of the surface facets of III–V nanowires on their failure during tensile deformation. We find that wurtzite (WZ) nanowires can withstand higher levels of stress and strain at failure compared to zinc-blende (ZB) nanowires. We observe that it is easier to nucleate a crack on a ZB nanowire due to the stress singularities that occur at the intersection of two opposing {111} facets. In WZ nanowires, we observe that cracks always nucleate at the intersection between two adjacent {112} surface facets. We explain these phenomena using fracture mechanics techniques based on energetics of crack formation.     

The Baltic Churches and the Challenges of the Post-Communist World

This article analyses and describes the recent history of the Baltic churches, their theological reorientation and the challenges they have encountered in the post-Communist Baltic society. The focus is on the Estonian, Latvian and Lithuanian Lutheran churches whereas the Catholic and Orthodox churches receive less attention. It is first demonstrated that much has changed since the Second World War regarding the churches' membership numbers and their societal position. The article then pays attention to two phenomena that have caused much discussion not only within the churches but also among foreign observers: the fear that the Lutheran Church will surrender to the Catholic Church, and the quite opposite anxiety that the Lutheran Church–Missouri Synod will grow too influential within Baltic Lutheranism. Finally, the author examines the way the Baltic churches have been involved in politics during the last two decades.     

From state church to faith community: an analysis of worldly and spiritual power in the Church of Sweden

The aim of this article is to discuss the current legislation, and power structures in and between different levels of the Church of Sweden in terms of church–state relations and secularisation, with the help of theories from sociology of religion and ecclesiology drawn from José Casanova, Grace Davie and Avery Dulles. With themes from Lutheran theology, including the two regiments and the common priesthood of all believers, we analyse the current legislation and power structures from the perspective of the so-called ‘dual line of responsibility’. The underlying hypothesis is that the structures of the former state church are still deciding the power structures in the Church of Sweden. This creates obscurity concerning the role of the church in public society and negatively affects the ecclesiastical development of the church now that it has lost its earlier status as a state church.     

Subjectivist – observing and objective – participant perspectives on the world: Kant,aquinas and quantum mechanics

Theological thinking is influenced by perspectives on the relation of scientific knowledge to reality. Two paradigms for understanding the nature of human knowledge are considered in relation to quantum mechanics: the subjective-observing perspective of Kant, and the objective-participant perspective of Thomas Aquinas. I discuss whether quantum mechanics necessarily implies a subject centered perspective on reality, and argue, with reference to d'Espagnat's notion of veiled reality, that quantum non-separability challenges this view. I then explore whether the objective-participant perspective of Thomas Aquinas provides a more fruitful context for understanding quantum mechanics. I discuss quantum measurement in terms of the transition from potentiality to actuality, and knowledge as the latent intelligibility of the world realized. However, the negative nature of our knowledge of quantum non-separability also challenges this perspective. Our theological thinking in response to quantum knowledge must therefore proceed tentatively, balancing a via positiva, with a via negativa.     

The Rationality of Ultimate Concern: Moral Exemplars,Theological Ethics,and the Science of Moral Cognition

This paper argues that consideration of moral exemplars may provide a means for integrating insights across philosophical ethics, theological ethics, and the scientific study of moral cognition. Key to this endeavor is an understanding of the relation of cognition and emotion in ethical decision-making, a relation that is usually understood to be oppositional but which in proper circumstances may be understood to be quite the opposite. Indeed, a distinctive feature of moral exemplarity may consist in the ability to properly integrate the emotions into the moral life, and reference to and imitation of exemplars may involve a referencing and imitating of the emotions of the exemplar.