Molecular structural studies of the amorphous mineral pitticite Fe, AsO4, SO4, H2O

Some minerals are colloidal and show no X-ray diffraction patterns. Vibrational spectroscopy offers one of the few methods for the assessment of the structure of these types of mineral. Among this group of minerals is pitticite simply described as Fe, AsO4, SO4, H2O. The objective of this research is to determine the molecular structure of the mineral pitticite using vibrational spectroscopy. Raman microscopy offers a useful method for the analysis of such colloidal minerals. Raman and infrared bands are attributed to the , and water stretching vibrations. The Raman spectrum is dominated by a very intense sharp band at 983 cm−1 assigned to the symmetric stretching mode. A strong Raman band at 1041 cm−1 is observed and is assigned to the antisymmetric stretching mode. Low intensity Raman bands at 757 and 808 cm−1 may be assigned to the antisymmetric and symmetric stretching modes. Raman bands observed at 432 and 465 cm−1 are attributable to the doubly degenerate ν2(SO4)2- bending mode.

Fluid-structure interaction analysis by coupled FE-SPH model based on a novel searching algorithm

Fluid–Structure Interaction (FSI) problem is significant in science and engineering, which leads to challenges for computational mechanics. The coupled model of Finite Element and Smoothed Particle Hydrodynamics (FE-SPH) is a robust technique for simulation of FSI problems. However, two important steps of neighbor searching and contact searching in the coupled FE-SPH model are extremely time-consuming. Point-In-Box (PIB) searching algorithm has been developed by Swegle to improve the efficiency of searching. However, it has a shortcoming that efficiency of searching can be significantly affected by the distribution of points (nodes in FEM and particles in SPH). In this paper, in order to improve the efficiency of searching, a novel Striped-PIB (S-PIB) searching algorithm is proposed to overcome the shortcoming of PIB algorithm that caused by points distribution, and the two time-consuming steps of neighbor searching and contact searching are integrated into one searching step. The accuracy and efficiency of the newly developed searching algorithm is studied on by efficiency test and FSI problems. It has been found that the newly developed model can significantly improve the computational efficiency and it is believed to be a powerful tool for the FSI analysis.

Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface

Magnetic atoms at surfaces are a rich model system for solid-state magnetic bits exhibiting either classical(1,2) or quantum(3,4) behaviour. Individual atoms, however, are difficult to arrange in regular patterns(1-5). Moreover, their magnetic properties are dominated by interaction with the substrate, which, as in the case of Kondo systems, often leads to a decrease or quench of their local magnetic moment(6,7). Here, we show that the supramolecular assembly of Fe and 1,4-benzenedicarboxylic acid molecules on a Cu surface results in ordered arrays of high-spin mononuclear Fe centres on a 1.5nm square grid. Lateral coordination with the molecular ligands yields unsaturated yet stable coordination bonds, which enable chemical modification of the electronic and magnetic properties of the Fe atoms independently from the substrate. The easy magnetization direction of the Fe centres can be switched by oxygen adsorption, thus opening a way to control the magnetic anisotropy in supramolecular layers akin to that used in metallic thin films.

Composition-controlled metal-insulator transitions and minimum metallic conductivity in the oxide systems LaNi1-xMxO3 (M = Cr, Mn, Fe, or Co)

The composition-controlled metal-insulator transition in the perovskite systems LaNi1-xMxO3 (M = Cr, Mn, Fe, and Co) has been investigated by transport measurements over the temperature range 12-300 K. These systems, which have critical electron densities (nc) in the range (1-2) -1020 electrons cm-3, exhibit sharp metal-insulator transitions at the base temperature. The corresponding minimum metallic conductivity (Ï-min), separating the localized and itinerant electronic regimes, is of the order of 102 ohm-1 cm-1. Particular attention is paid to the idea of Ï-min scaling with nc, and our present results are compared with earlier studies of the metal-insulator transition in low (e.g., Ge:Sb) and high (e.g., metal-ammonia, supercritical Hg) electron-density systems. A link is established between the transport and magnetic properties of the title systems at the metal-insulator transition.

Influence of heat treatment on the strength and fracture behaviour of Fe-12Cr-6Al ferritic stainless steel

The changes in the tensile properties and fracture mode brought about by heat treatment of Fe-12Cr-6Al ferritic stainless steel have been studied. A favourable combination of high strength and good ductility is obtained by heating the material at 1370 K for 2 h followed by a water quench. The high-temperature treatment results in carbide dissolution as well as an increase in the grain size. The mechanism of strengthening has been evaluated from the apparent activation energy (28 kJ mol–1) and is identified to be the unpinning of dislocations from the atmosphere of carbon atoms. As the heat-treatment temperature is increased, the fracture behaviour changes from ductile to brittle mode and this is related to the changes in grain size and friction stress.

Preparation, structure, and magnetic properties of isostructural La3MAlS7 and La3MFeS7 (M = Mg, Mn, Fe, Co, Ni, or Zn)

A series of quaternary metal sulfides of the general formula La3MM′S7 (M = Mn, Fe, Co; M′ = Al and M = Mg, Mn, Fe, Co, Ni; M′ = Fe) consisting of linear chains of face shared MS6 octahedra and isolated M′S4 tetrahedra has been prepared and studied. The aluminium compounds La3MAlS7 (M = Mn, Fe, Co) exhibit linear chain antiferromagnetism. Magnetic behavior of other La3MFeS7 sulfides has been examined in detail. The magnetic susceptibility of La3MgFeS7 shows that tetrahedral site Fe3+ undergoes a transition from Image to S = 2 spin state around 150 K.

Ce CORE level X-ray photo electron spectroscopy of CeX2Si2 (X = Fe, Co, Ni and Cu)

Ce(3d) and (4d) core level XPS spectra of CeX = Fe, Co, Ni and Cu) suggest that the mean valence of Ce was as well as 4f hybridization strength decrease systematically from Fe to Cu. This observation is in agreement with the results of Bremstrahlung Isochromat Spectroscopy (BIS), but in disagreement with LIII-edge data reported earlier.

Synthesis, characterization and photocatalytic activity of MxCe1-xVO4 (M = Li, Ca and Fe)

Non-stoichiometric substituted cerium vanadates, MxCe1-xVO4 (M = Li, Ca and Fe), were synthesized by solid-state reactions. The crystal structure was analyzed by powder X-ray diffraction and it exhibits a tetragonal zircon Structure, crystallizing in the space group I4(1)/amd with a = 7.3733(4) and c = 6.4909(4) angstrom and Z = 4. Particle sizes were in the range of 600-800 nm, as observed by scanning electron microscopy. The thermal analysis of the compounds showed phase stability up to 1100 degrees C. The UV diffuse reflectance spectra indicated that the compounds have band gaps in the range of 2.6-2.9 eV. The photocatalytic activity of these Compounds was investigated for the first time for the degradation of different dyes, and organics, the oxidation of cyclohexane and the hydroxylation of benzene. The degradation of dyes was modeled using the Langmuir-Hinshelwood kinetics, while the oxidation of cyclohexane and hydroxylation of benzene were modeled using a free radical mechanism and a series reaction mechanism, respectively.

Konstruktiivisen linjakkuuden perusteita etsimässä : Systemaattinen analyysi John Biggsin esittämistä yliopisto-opetuksen lähtökohdista

The aim of this study is to explore by systematic textual analysis the crucial conceptions of constructive alignment and to reconstruct the concept of constructive alignment and examine the relation between conceptual relationships in John Biggs’s texts. In this study, I have also analyzed the presuppositions of the concept of constructive alignment and its possible implications. The research material includes Biggs’s (1996b; 2003) article entitled Enhancing Teaching through Constructive Alignment and book entitled Teaching for Quality Learning at University. The primary purpose of the systematic textual analysis is to reconstruct concepts and gain access to a new or more profound understanding of the concepts. The main purpose of the constructive alignment is to design a teaching system that supports and encourages students to adopt a deep approach learning. At the center of the constructive alignment are two concepts: constructivism in learning and alignment in teaching. A tension was detected between these concepts. Biggs assumes that students’ learning activities are primed by the teaching. Because of this it is not important what the teacher does. At the same time he emphasizes that teaching interacts with learning. The teacher’s task is to support student’s appropriate learning activities. On the basis of the analysis, I conclude these conceptions are not mutually exclusive. Interaction between teaching and learning has an effect on student’s learning activities. The most essential benefit of the model of constructive alignment is that Biggs brings together and considers teaching at the same level with learning. A weakness of Biggs’s model relates to the theoretical basis and positions of the concept of constructive alignment. There are some conflicts between conceptions of epistemology in Biggs’s texts. In addition, Biggs writes about constructivism also as conceptions of epistemology, but doesn’t consider implications of that position or what follows or doesn’t follow from that commitment. On the basis of the analysis, I suggest that constructivism refers in Biggs’s texts rather to constructivism in learning than philosophical constructivism. In light of this study, constructive alignment doesn´t lead to philosophical constructivism. That’s why constructive alignment stays out of idealism. Biggs’s way of thinking about teachers possibility to confronting students’ misconceptions and evaluate and assess students’ constructions support a realist purpose in terms of philosophical stance. Realism does not drift toward general problems of relativism, like lack of criteria for assessing or evaluate these constructions.

Kotitaloustaidon ulottuvuuksia : Analyysi kotitaloustaidosta eksistentialistis-hermeneuttisen fenomenologian valossa

DOMESTIC SKILLS AS THE ART OF EVERYDAY LIFE. An inquiry about domestic skills as a way of being-in-the-world in the light of existentialist-hermeneutics phenomenology. This study focuses on analyzing domestic skills in a phenomenological manner. The description phenomenological emerges from the interpretation process, which originates from the ontological question of domestic skills. The ontological question of how domestic skills are directs one s phenomenological gaze to the experiencing of domestic skills, rather than merely viewing their action or technical aspects. Along with the ontological question, the axiological question of what the meaning of domestic skills is drives the analysis. This study is both theoretical and philosophical. Phenomenology is the guiding philosophy, theory and methodology of the inquiry. Existentialist-hermeneutics is the emphasis which most appropriately describes the phenomenological attitude adopted within the analysis. Martin Heidegger s philosophy of being and Maurice Merleau-Ponty s philosophy of the lived body essentially form the theoretical base for the inquiry. The analysis reveals domestic skills within a core of Care and the Other. Care and the Other are anchored both in Heidegger s analysis of Dasein and in Merleau-Ponty s analysis of the reversible being-in-the-world. The social nature of being and the action-oriented intentionality of the lived body are embodied in Care and the Other. This ontological base of domestic skills enables us to see the extensions that inhabit in it. These extensions are redoing, emotional experiencing, adapting and emancipating. The analysis connects ability and action, which is why domestic skills and household activity must be seen as a united whole. This united whole is not the matter of the two components of the phenomenon, but is rather the matter of domestic skills as a way of being-in-the-world. Domestic skills are a channel for the phenomenon Home Economics to manifest in our lives. This is the gaze that presents domestic skills as to be like the poetry of everyday life. The main result of the study is the elucidation of the ontology of domestic skills and the naming of its extensions. This growth of philosophical understanding makes it possible to strengthen the science of home economics.