Structural rationalization of the microhardness trends of rare-earth aluminosilicate glasses: Interplay between the RE3+ field-strength and the aluminum coordinations

AbstractMany studies have sought to rationalize property/structure relationships in rare-earth (RE) bearing aluminosilicate oxide or oxynitride glasses. In a set of 48 RE2O3–Al2O3–SiO2 (RE=La, Y, Lu, Sc) glasses of widely spanning compositions and RE3+ cation field-strengths (CFS), we observe strong correlations between the microhardness, glass compactness, and the average coordination number of Al. We argue that the well-known microhardness elevation for increasing RE3+ CFS stems not primarily from the RE3+ ions themselves, as hitherto believed, but merely from a structure-strengthening by AlO5/AlO6 polyhedra that cross-link different glass–network segments. The high-coordination Al populations grow together with the RE3+ CFS

Upp från den torra marken : att leta efter vattenkonstruktioner i Salton Sea området

This thesis explores constructed water landscapes and the attitudes creating them in the Salton Sea area, which is located in the converge of the Mojave and the Sonoran Deserts in southeast California. With the focus on water constructions the thesis embraces the method of the Deviant Transect, under development by the landscape architect researchers Gini Lee and Lisa Diedrich, with Ellen Braae. The method aims at enabling designers to capture qualities that can only be perceived on site, such as dynamics, relationships and atmospheres, in order to support site-specific transformation of sites. This thesis challenges Antropocentrism, inspired by writings of Dirk Sijmons (2014) and Saskia Sassen (2014). Amongst others, Carol J. Burns and Andrea Kahn’s (2005) theories on site and site specificity, are studied, along with literature on grass root movements and societal change suggested by Grace Lee Boggs (2011) . This work examines water constructions in the Salton Sea area, acknowledging them in two ways: as land colonization with themes such as water systems, industrial scaled farming, and sub-urban settlements, and as oppositions to conventional land use practices, with themes of the desert as a garden, local food, and the culture of mobile homes. The resulting findings are the basis for a design proposal that acknowledges what is already in place by introducing a network of test sites. The aim is to use landscape architectural skills in order to engage in a speculative form of regional design, enabling visionary organizing rather than providing finished blueprints

The new Kiruna : competition entry and utopian example

Kiruna står nu inför en unik omvandling då staden ska omlokaliserar på grund av utvidgningen av gruvdriften. En arkitekttävling har nyligen genomförts om utformning och användning av det nya Kiruna. Syftet med denna uppsats var att studera relationen mellan stadsbyggnadsutopin The Linear City och det vinnande tävlingsbidraget Kiruna 4-ever. För en ökad förståelse för dagens Kiruna är Hallmans stadsplan för Kiruna och dess koppling till svenska och engelska trädgårdsstäder viktig. I bakgrunden behandlas även arkitekttävlingens program och juryutlåtande. Arbetet har utförts som en litteraturstudie med fokus på de intentioner gällande fysisk form och användning som förslagsställare och teoretiker presenterat. Resultatet visar att beröringspunkterna mellan förslag och teori är många. Skillnaderna blir tydliga i framförallt synen på hållbarhet där Kiruna 4-ever till skillnad mot The Linear City tar ett grepp om den ekologiska hållbarheten. En annan skillnad är inställningen till höghus där Kiruna 4-ever använder dem för att uppnå en högre densitet. I The Linear City identifieras höghus som ett problem för social hållbarhet. I uppsatsen diskuteras också vad en utopisk förebild kan tillföra ett gestaltningsförslag. En möjlig slutsats är att en teoretisk grund underlättar för förslagsställare att presentera ett lättöverskådligt förslag. Frågan om hur utopiskt det vinnande förslaget är diskuteras slutligen. I dialogen med Kiruna-borna, näringslivet, LKAB och kommunen avgörs hur stora förändringarna i Kiruna 4-ever blir. Frågor som till exempel om Kiruna-borna verkligen vill bo i höghus längs en huvudgata, eller för den delen radhuslängor, kommer bli avgörande för hur homogent staden utvecklas och därmed hur mycket av förslaget Kiruna 4-ever som blir genomfört.Kiruna is now facing a unique transformation as the city is relocated due to the expansion of mining operations. An architectural competition has recently been carried out on the design and use of the new Kiruna. The puropse of this paper was to study the relationship between the urban planning utopia The Linear City and the winning competition entry Kiruna 4-ever. For a better uderstanding of today´s Kiruna is Hallman´s urban plan för Kiruna and its link to Swedish and English garden cities important. The background also dealt with the architectural competition program and the jurys assessment. The work has been carried out as a literature review focused on the intentions of physical form and use that proponents and theortists presented. The result shows that the interface between the proposal and the theory are numerous. Some differences are however obvious, particularly in the view of sustainability where Kiruna 4-ever, unlike The Linear City, takes a grip on the ecological sustainability. Another difference is the attitude towards high-rise buildings where Kiruna 4-ever uses them to achieve a higher density. In The Linear City high-rise buildings are identified as a problem for social sustainability. The paper also discusses what a utopian model can provide a competitionproposal. One possible conclusion is that a theoretical foundation facilitates the task of presenting an suggestion that is easy to grasp. Finally, the question of how utopian the winning proposal are, is discussed. The dialogue with the residents of Kiruna, the business community, LKAB and the municipality determines how big the changes in Kiruna will be. Questions such as whether the residents of Kiruna really want to live in high-rise buildings along a main road, or for that matter terrace houses, will be crucial to how homogeneous the city is being developed and consequently to which extent the proposal Kiruna 4-ever becomes implemented

Social pedagogy versus social work in a Swedish context

In Sweden there are several different professions that work within the welfare sector. Two of these are social pedagogues and socionoms. This article examines the similarities and differences between these professional fields by exploring four areas in more detail: education, the history of ideas and theory, research and practice. The results show that there are not only many differences but also some similarities. In practical work, social pedagogues and socionoms often work side by side and perform similar tasks. They are located in the same areas and often use the same methods. When it comes to the differences in educational history and current educations, they are large although they can also be found in, for example, the history of ideas. Furthermore, research in the various areas differs. In social pedagogy the interest has to a greater extent been focused on an understanding of the discipline through studies of the history of ideas, while in social work today one often focuses on studies of professional methods. Today’s challenges in the welfare sector require new knowledge, ways of thinking and understanding. Here, social pedagogy with its philosophical roots and humanistic values can play an important role

Registro notable del Perro de Orejas Cortas Atelocynus microtis (Carnivora: Canidae) en el trapecio amazónico, Colombia.

Atelocynus microtis is one of the least known species of carnivores in the world, known only from sporadic records throughout its distribution (Michalski 2010, Leite-Pitman & Williams 2011). It is distributed between Colombia and Bolivia and Ecuador, Peru and Brazil, with very few records and in relatively large time windows (Berta 1986, LeitePitman & Williams 2011).Atelocynus microtis es una de la especies menos conocidas de carnívoros en el mundo, conocido apenas de registros esporádicos a lo largo de su distribución (Michalski 2010, Leite-Pitman & Williams 2011). Se distribuye entre Colombia y Bolivia y Ecuador, Perú y Brasil, con muy pocos registros y en ventanas de tiempo relativamente grandes (Berta 1986, LeitePitman & Williams 2011). &nbsp

NMR investigations of interactions between anesthetics and lipid bilayers

Interactions between anesthetics (lidocaine and short chain alcohols) and lipid membranes formed by dimyristoylphosphatidylcholine (DMPC) were studied using NMR spectroscopy. The orientational order of lidocaine was investigated using deuterium NMR on a selectively labelled compound whereas segmental ordering in the lipids was probed by two-dimensional 1H-13C separated local field experiments under magic-angle spinning conditions. In addition, trajectories generated in molecular dynamics (MD) computer simulations were used for interpretation of the experimental results. Separate simulations were carried out with charged and uncharged lidocaine molecules. Reasonable agreement between experimental dipolar interactions and the calculated counterparts was observed. Our results clearly show that charged lidocaine affects significantly the lipid headgroup. In particular the ordering of the lipids is increased accompanied by drastic changes in the orientation of the P-N vector in the choline group

Composition-dependent in vitro apatite formation at mesoporous bioactive glass-surfaces quantified by solid-state NMR and powder XRD

Silicate-based bioactive glasses exhibit bone-bonding properties due to the formation of a hydroxycarbonate apatite (HCA) layer at the glass surface on its contact with living tissues. This bone-healing process is triggered by ionic exchange between the glass and the surrounding fluids and thereby depends on the glass composition. In this work, the HCA formation from three mesoporous bioactive glasses (MBGs) of different compositions immersed in a simulated body fluid (SBF) was monitored for variable time intervals between 15 minutes to 30 days. By utilizing two independent assessment techniques, solid-state P-31 NMR spectroscopy and powder X-ray diffraction (PXRD), we report the first quantitative assessment of the HCA growth (i.e., "in vitro bioactivity") from a bioactive glass: both techniques allow for monitoring the crystallization of the amorphous calcium phosphate (ACP) precursor into HCA, i.e., a profile of the relative ACP/HCA fractions of the biomimetic phosphate layer formed at each MBG surface and SBF-exposure period. The amount of HCA present in each solid specimen after the SBF treatment, as well as the composition of the remaining cation-depleted MBG phase, was determined from PXRD data in conjunction with measured concentrations of Ca, Si, and P in the solution. In contrast with previous findings from in vitro bioactivity assessments of the same MBG compositions, the HCA formation is herein observed to increase concurrently with the Ca and P contents of the MBG; these apparently different composition-bioactivity observations stem from a significantly lower MBG-loading in the SBF solution utilized herein. The results are discussed in relation to the general task of performing bioactivity testing in SBF, where we highlight the importance of adapting the concentration of the biomaterial to its composition to avoid perturbing the HCA crystallization and thereby altering the outcome of the test

Proton Environments in Biomimetic Calcium Phosphates Formed from Mesoporous Bioactive CaO-SiO2- P2O5 Glasses in vitro: Insights from Solid-State NMR

When exposed to body fluids, mesoporous bioactive glasses (MBGs) of the CaO{SiO2{P2O5 system develop a bone-bonding surface layer that initially consists of amorphous calcium phosphate(ACP), which transforms into hydroxy-carbonate apatite (HCA) with a very similar composition as bone/dentin mineral. Information from various 1H-based solid-state nuclear magnetic resonance (NMR) experiments were combined to elucidate the evolution of the proton speciations both at the MBG surface and within each ACP/HCA constituent of the biomimetic phosphate layer formed when each of three MBGs with distinct Ca, Si, and P contents was immersed in a simulated body fluid (SBF) for variable periods between 15 min and 30 days. Directly excited magic-angle-spinning (MAS) 1H NMR spectra mainly reflect the MBG component, whose surface is rich in water and silanol (SiOH) moieties. Double-quantum{single-quantum correlation 1H NMR experimentation at fast MAS revealed their interatomic proximities. The comparatively minor H species of each ACP and HCA component were probed selectively by heteronuclear 1H{31P NMR experimentation. The initially prevailing ACP phase comprises H2O and "non-apatitic" HPO2

Nuclear Magnetic Resonance and Metadynamics Simulations Reveal the Atomistic Binding of l -Serine and O-Phospho- l -Serine at Disordered Calcium Phosphate Surfaces of Biocements

Interactions between biomolecules and structurally disordered calcium phosphate (CaP) surfaces are crucial for the regulation of bone mineralization by noncollagenous proteins, the organization of complexes of casein and amorphous calcium phosphate (ACP) in milk, as well as for structure-function relationships of hybrid organic/inorganic interfaces in biomaterials. By a combination of advanced solid-state NMR experiments and metadynamics simulations, we examine the detailed binding of O-phospho-l-serine (Pser) and l-serine (Ser) with ACP in bone-adhesive CaP cements, whose capacity of gluing fractured bone together stems from the close integration of the organic molecules with ACP over a subnanometer scale. The proximity of each carboxy, aliphatic, and amino group of Pser/Ser to the Ca2+ and phosphate species of ACP observed from the metadynamics-derived models agreed well with results from heteronuclear solid-state NMR experiments that are sensitive to the 13C-31P and 15N-31P distances. The inorganic/organic contacts in Pser-doped cements are also contrasted with experimental and modeled data on the Pser binding at nanocrystalline HA particles grown from a Pser-bearing aqueous solution. The molecular adsorption is driven mainly by electrostatic interactions between the negatively charged carboxy/phosphate groups and Ca2+ cations of ACP, along with H bonds to either protonated or nonprotonated inorganic phosphate groups. The Pser and Ser molecules anchor at their phosphate/amino and carboxy/amino moieties, respectively, leading to an extended molecular conformation across the surface, as opposed to an "upright standing"molecule that would result from the binding of one sole functional group