Bioactive sol-gel glasses at the atomic scale:the complementary use of advanced probe and computer modeling methods

Sol-gel-synthesized bioactive glasses may be formed via a hydrolysis condensation reaction, silica being introduced in the form of tetraethyl orthosilicate (TEOS), and calcium is typically added in the form of calcium nitrate. The synthesis reaction proceeds in an aqueous environment; the resultant gel is dried, before stabilization by heat treatment. These materials, being amorphous, are complex at the level of their atomic-scale structure, but their bulk properties may only be properly understood on the basis of that structural insight. Thus, a full understanding of their structure-property relationship may only be achieved through the application of a coherent suite of leading-edge experimental probes, coupled with the cogent use of advanced computer simulation methods. Using as an exemplar a calcia-silica sol-gel glass of the kind developed by Larry Hench, in the memory of whom this paper is dedicated, we illustrate the successful use of high-energy X-ray and neutron scattering (diffraction) methods, magic-angle spinning solid-state NMR, and molecular dynamics simulation as components to a powerful methodology for the study of amorphous materials

Preservation of York Minster historic limestone by hydrophobic surface coatings

Magnesian limestone is a key construction component of many historic buildings that is under constant attack from environmental pollutants notably by oxides of sulfur via acid rain, particulate matter sulfate and gaseous SO 2 emissions. Hydrophobic surface coatings offer a potential route to protect existing stonework in cultural heritage sites, however, many available coatings act by blocking the stone microstructure, preventing it from 'breathing' and promoting mould growth and salt efflorescence. Here we report on a conformal surface modification method using self-assembled monolayers of naturally sourced free fatty acids combined with sub-monolayer fluorinated alkyl silanes to generate hydrophobic (HP) and super hydrophobic (SHP) coatings on calcite. We demonstrate the efficacy of these HP and SHP surface coatings for increasing limestone resistance to sulfation, and thus retarding gypsum formation under SO/H O and model acid rain environments. SHP treatment of 19th century stone from York Minster suppresses sulfuric acid permeation

Kaupallisen kuosimalliston suunnittelu Intiassa : Soveltaen opittuja taitoja tekstiilisuunnittelijana toimimiseen

Opinnäytetyön tutkimusosuuden tarkoitus oli tutkia intialaisen tekstiilitoimiston toimintatapoja ja työkulttuuria. Tavoitteena oli tuoda esille, miten tänä päivänä yksi johtavista talousmahdista kilpailee eurooppalaisilla markkinoilla. Lähtökohtana oli kaupallisen kuosimalliston suunnittelu länsimaalaisille kuluttajille. Tutkimusosuudessa opinnäytetyön tekijä heijasteli omia kokemuksia Intiassa työskentelystä ja haastatellen intialaista tekstiilisuunnittelija Geetika Gulia, joka asuu nykyään Suomessa. Projektiosuus on kuosimalliston suunnittelu tekijän omalle toiminimelle Johanna Elisabet. Projektissa tavoite oli käyttää opittuja taitoja Intiasta ja suunnitella kaupallinen keittiötekstiilikuosimallisto eurooppalaisille kuluttajille. Opinnäytetyön tavoite oli markkinoida kirjoittajan osaamista tekstiilisuunnittelijana. Työssä haluttiin visuaalisesti tuoda esille vahvuudet trendien ennustamisessa ja keittiötekstiilimalliston suunnittelussa.The goal of the research of this Thesis was to study the working habits and working culture of textiles studios in India. The aim was to bring out the metods how one of the leading and economically powerful countries is competing on the European market. The starting point was to design a commercial textile design collection for the western consumers. In this research the Author’s own experiences and observations were reflected and analyzed while working in India. Also her interview with Geetika Gulia was included, a freelance textile designer and currently living in Finland. The practical project for the Thesis was to design a commercial textile collection for the Author’s limited company Johanna Elisabet. The goal was to use the skills learned in India and design a commercial textile collection for the European consumer. The aim for the thesis was to showcase the Author’s person and skills as a textile designer. She visually demonstrates her skills on the trend research and designing a kitchen textile collection

Synthesis and coordination chemistry of a diphospha-tetrathia macrocycle, 1,10-diphenyl-1,10-diphospha-4,7,13,16-tetrathiacyclooctadecane

Reaction of 1,2-dichloroethane with PhP(CH2CH2SH)(2) and caesium carbonate affords 1,10-diphenyl-1,10-diphospha-4,7,13,16-tetrathiacyclooctadecane (18P2S4) in high yield (ca. 90%). 18P2S4 slowly decomposes in solution to afford insoluble PhP(S)(CH2CH2SCH2CH2SCH2CH2)(2)P(S)Ph which was characterised by single crystal X-ray diffraction. Reaction of 18P2S4 with [Ni(H2O)(6)](BF4)(2) or Fe(BF4)(2) affords [M(18P2S4)](BF4)(2) (M = Ni or Fe). The structure of [Ni(18P2S4)](2+) is a tetragonally distorted octahedron in which there are two short Ni-S bonds [2.2152(6) Angstrom] and two long Ni-S bonds [2.9268(6) Angstrom]. For comparison the structure of [Ni(9PS2)(2)](2+) was determined and found to a have a similar, but less marked distortion, in which the difference between the long and short bonds is ca. 0.5 Angstrom. In contrast the structure of [Fe(18P2S4)](2+) is octahedral with approximately equal Fe-S bonds. The electrospray mass spectra of the cations [M(9PS2)(2)](2+) and [M(18P2S4)](2+) (M=Ni or Fe) all display ethene loss from the ligands as has been previously observed with trithiacyclononane complexes. The results of P-C and C-S bond rupture were also observed in the reaction of ruthenium(III) triflate with 9PS2 which unexpectedly afforded crystals containing [Ru2(S)(2)(18P2S4)(2)], in which the two ruthenium centres are bridged by two sulfides and the two 18P2S4 ligands coordinated only through the phosphine centres. Also present in the crystals was one equivalent of tetrathiacycloundecane (12S4)

Probing the local structural environment of calcium by natural-abundance solid-state Ca-43 NMR

New natural-abundance Ca-43 magic angle spinning (MAS) NMR data measured at high magnetic field (14.1 T) is presented for a range of crystalline calcium-containing binary and ternary inorganic compounds. The combination of high field, moderate MAS (up to 4.5 kHz), and large sample volume (a 9.5 mm diameter MAS rotor) means that a good signal-to-noise ratio can generally be obtained in a time (similar to12 h) that makes Ca-43 NMR a feasible approach for determining information about calcium siting in a wide range of materials of physical interest. This study greatly increases the number of Ca-43 NMR parameters determined for solid materials in the literature, extending reports to local nearest-neighbor coordinations to other than oxygen. These data show that the isotropic chemical shift range is >250 ppm and typically that the quadrupole interaction is <4 MHz. In ternary compounds where Ca is coordinated in the nearest-neighbor shell by only oxygen, the isotropic Ca-43 chemical shift correlates well to the mean Ca-O distance, consistent with the only previous study. In binary compounds the isotropic Ca-43 chemical shift does not appear to be correlated with the mean Ca-X bond length. The extension of natural-abundance Ca-43 MAS NMR studies to amorphous materials are reported by examining sol-gel prepared calcium silicate materials. The data show that in the initial amorphous mixture at lower temperatures (120-350degreesC) the calcium environment is more like that in the parent calcium nitrate than a silicate, and that further heat treatment causes very significant broadening of the calcium resonance. The implications of this observation for the use of natural-abundance Ca-43 MAS NMR structural studies of amorphous materials are examined

XAS_bioactive xerogel_Ca K_May04_F Sow et al

Scanned laboratory books for experiments 200