Rietveld refinement of the crystal structures of Rb2X Si5O12 (X = Ni, Mn)

The synthetic leucite silicate framework mineral analogues Rb2XSi5O12 {X = Ni [dirubidium nickel(II) pentasilicate] and Mn [dirubidium manganese(II) pentasilicate]} have been prepared by high-temperature solid-state synthesis. The results of Rietveld refinements, using X-ray powder diffraction data collected using Cu K[alpha] X-rays, show that the title compounds crystallize in the space group Pbca and adopt the cation-ordered structure of Cs2CdSi5O12 and other leucites. The structures consist of tetrahedral SiO4 and XO4 units sharing corners to form a partially substituted silicate framework. Extraframework Rb+ cations sit in channels in the framework. All atoms occupy the 8c general position for this space group. In these refined structures, silicon and X atoms are ordered onto separate tetrahedrally coordinated sites (T-sites). However, the Ni displacement parameter and the Ni—O bond lengths suggest that for the X = Ni sample, there may actually be some T-site cation disorder

Rietveld refinements of the crystal structures of Rb2XSi5O12 (X = Mn, Ni)

Poster Number: CCG06 Synthetic analogues of the silicate framework mineral leucite (KAlSi2O6) with the stoichiometry Rb2XSi5O12 (X = Mn, Ni) have been prepared by high temperature solid-state synthesis. Ambient temperature X-ray powder diffraction data have been collected on these samples. Analysis of these powder diffraction data show that these samples both consist of single phases [1] isostructural with the Pbca cation-ordered framework leucite structure of Cs2CdSi5O12 [2]. Rietveld refinement [3] shows that for X = Mn this crystal structure has complete Mn and Si cation order over the tetrahredrally coordinated sites (T-sites) in the silicate framework. However, for X = Ni, Rietveld refinement suggests that there may be some Ni and Si cation T-site cation disorder

Sacred communities: contestations and connections

This article discusses a project whose purpose was to review existing qualitative and quantitative data from two separate studies to provide new insights about everyday religion and belonging. Researchers engaged in knowledge exchange and dialogue with new and former research participants, with other researchers involved in similar research, and with wider academic networks beyond the core disciplines represented here, principally anthropology and geography. Key concluding themes related to the ambivalent nature of ‘faith’, connections over place and time, and the contested nature of community. Implicit in terms like ‘faith’, ‘community’, and ‘life course’ are larger interwoven narratives of space, time, place, corporeality, and emotion. The authors found that understanding how places, communities, and faiths differ and intersect requires an understanding of social relatedness and boundaries

Successful use of axonal transport for drug delivery by synthetic molecular vehicles

We report the use of axonal transport to achieve intraneural drug delivery. We constructed a novel tripartite complex of an axonal transport facilitator conjugated to a linker molecule bearing up to a hundred reversibly attached drug molecules. The complex efficiently enters nerve terminals after intramuscular or intradermal administration and travels within axonal processes to neuron cell bodies. The tripartite agent provided 100-fold amplification of saturable neural uptake events, delivering multiple drug molecules per complex. _In vivo_, analgesic drug delivery to systemic and to non-targeted neural tissues was greatly reduced compared to existing routes of administration, thus exemplifying the possibility of specific nerve root targeting and effectively increasing the potency of the candidate drug gabapentin 300-fold relative to oral administration

Ex-vivo HRMAS of adult brain tumours: metabolite quantification and assignment of tumour biomarkers

Background: High-resolution magic angle spinning (HRMAS) NMR spectroscopy allows detailed metabolic analysis of whole biopsy samples for investigating tumour biology and tumour classification. Accurate biochemical assignment of small molecule metabolites that are “NMR visible” will improve our interpretation of HRMAS data and the translation of NMR tumour biomarkers to in-vivo studies. Results: 1D and 2D 1H HRMAS NMR was used to determine that 29 small molecule metabolites, along with 8 macromolecule signals, account for the majority of the HRMAS spectrum of the main types of brain tumour(astrocytoma grade II, grade III gliomas, glioblastomas, metastases, meningiomas and also lymphomas). Differences in concentration of 20 of these metabolites were statistically significant between these brain tumour types. During the course of an extended 2D data acquisition the HRMAS technique itself affects sample analysis: glycine, glutathione and glycerophosphocholine all showed small concentration changes; analysis of the sample after HRMAS indicated structural damage that may affect subsequent histopathological analysis. Conclusions: A number of small molecule metabolites have been identified as potential biomarkers of tumour type that may enable development of more selective in-vivo 1H NMR acquisition methods for diagnosis and prognosis of brain tumours

Empirically Constrained Color-Temperature Relations. II. uvby

(Abriged) A new grid of theoretical color indices for the Stromgren uvby photometric system has been derived from MARCS model atmospheres and SSG synthetic spectra for cool dwarf and giant stars. At warmer temperatures this grid has been supplemented with the synthetic uvby colors from recent Kurucz atmospheric models without overshooting. Our transformations appear to reproduce the observed colors of extremely metal-poor turnoff and giant stars (i.e., [Fe/H]<-2). Due to a number of assumptions made in the synthetic color calculations, however, our color-temperature relations for cool stars fail to provide a suitable match to the uvby photometry of both cluster and field stars having [Fe/H]>-2. To overcome this problem, the theoretical indices at intermediate and high metallicities have been corrected using a set of color calibrations based on field stars having accurate IRFM temperature estimates and spectroscopic [Fe/H] values. Encouragingly, isochrones that employ the transformations derived in this study are able to reproduce the observed CMDs (involving u-v, v-b, and b-y colors) for a number of open and globular clusters (including M92, M67, the Hyades, and 47Tuc) rather well. Moreover, our interpretations of such data are very similar, if not identical, with those given by VandenBerg & Clem (2003, AJ, 126, 778) from a consideration of BV(RI)c observations for the same clusters. In the present investigation, we have also analyzed the observed Stromgren photometry for the classic Population II subdwarfs, compared our "final" (b-y)-Teff relationship with those derived empirically in a number of recent studies, and examined in some detail the dependence of the m1 index on [Fe/H].Comment: 70 pages, 26 figures. Accepted for publication in AJ (Feb 2004). Postscript version with high resolution figures and complete Table 3 available at http://astrowww.phys.uvic.ca/~jclem/uvb

Fiction Fix 08

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Rietveld refinement of Sr5(AsO4)3Cl from high-resolution synchrotron data

The apatite-type compound, penta­strontium tris­[arsenate(V)] chloride, Sr5(AsO4)3Cl, has been synthesized by ion exchange at high temperature from a synthetic sample of mimetite [Pb5(AsO4)3Cl] with SrCO3 as a by-product. The results of the Rietveld refinement, based on high resolution synchrotron X-ray powder diffraction data, show that the title compound crystallizes in the same structure as other halogenoapatites with general formula A 5(YO4)3 X (A = divalent cation, Y = penta­valent cation, and X = F, Cl or Br) in the space group P63/m. The structure consists of isolated tetra­hedral AsO4 3− anions (the As atom and two O atoms have m symmetry), separated by two crystallographically independent Sr2+ cations that are located on mirror planes and threefold rotation axes, respectively. One Sr atom is coordinated by nine O atoms and the other by six. The chloride anions (site symmetry ) are at the 2a sites and are located in the channels of the structure

Environment and Rural Affairs Monitoring & Modelling Programme – ERAMMP Report-26: ‘Quick Start’ Agricultural Small Sectors Modelling.

The potential impact of Brexit on the farming sector and wider environment is just one of the many challenges facing the Welsh Government. There are a range of decision and modelling tools which can be used to explore potential outcomes and the areas at risk where the environmental regulatory floor needs to be enhanced or social transition programmes put in place. To meet this challenge in Wales, a partnership between the Welsh Government, their stakeholders and a consortium of research organisations led by the UK Centre for Ecology and Hydrology (UKCEH) was formed. This partnership, called ERAMMP, (https://erammp.wales/en) combined expert knowledge and a range of decision and modelling tools to examine potential changes in agricultural land use that might result from Brexit, and to explore potential benefits of new land management options

Building a patient safety toolkit for use in general practice

Despite 340 000 000 primary care consultations annually in the UK, most of the literature on patient safety has focused on hospital-based services. To improve safety in primary care settings, we must know what methods, tools and indicators are available to measure and monitor patient safety. In collaboration with patient safety experts at the University of Dundee, we were able to identify a number of existing tools, and many of these were adopted for use in the Patient Safety Toolkit