Search results for "Refinement"
showing 10 items of 114 documents
Fundamental isomorphism theorems for quantum groups
2017
The lattice of subgroups of a group is the subject of numerous results revolving around the central theme of decomposing the group into "chunks" (subquotients) that can then be compared to one another in various ways. Examples of results in this class would be the Noether isomorphism theorems, Zassenhaus' butterfly lemma, the Schreier refinement theorem for subnormal series of subgroups, the Dedekind modularity law, and last but not least the Jordan-H\"older theorem. We discuss analogues of the above-mentioned results in the context of locally compact quantum groups and linearly reductive quantum groups. The nature of the two cases is different: the former is operator algebraic and the latt…
Heptane Adsorption in Silicalite-1: Neutron Scattering Investigation
2007
International audience; Structural properties of confined deuterated n-heptane in silicalite-1 have been investigated by neutron scattering experiments during the adsorption process. At 300 K, the adsorption isotherm shows a sharp inflection at a loading near Nads ) 4 molecules per silicalite-1 unit cell. In addition, the diffusivities obtained from recent QENS data exhibit a loading dependence. Our motivation is to find structural signatures of the peculiar behavior of n-heptane in silicalite-1 and to check the numerous computer simulation findings of this behavior. Our detailed neutron diffraction investigation agrees with the MONO-ORTHO phase transition of the silicalite-1 above a Nads v…
The crystal structure of 3,5-diisopropyl-4-nitropyrazole from X-ray powder diffraction data
2001
The crystal structure of 3,5-diisopropyl-4-nitropyrazole, 3c, has been determined by a Patterson Search method from laboratory X-ray powder diffraction data. The crystal data are: monoclinic symmetry with the unit-cell parameters aa 19:530O5U; ba 6:485O1U and ca 17:937O3U A; ba 100:32O1U8; space group I2/a ,C 9H15N3O2, Za 8, 293 K. After indexing the powder pattern by two methods, the unit-cell parameters found were refined by a least-squares technique. A whole pattern- fitting program was used to extract the integrated intensities. The structure was solved taking a related compound as a search model and the final Rietveld refinement converged to Rwpa 0.1971 and Rpa 0.1437. The structure pr…
[Be(ND 3 ) 4 ]Cl 2 : Synthesis, Characterisation and Space‐Group Determination Guided by Solid‐State Quantum Chemical Calculations
2013
Treatment of BeCl2 with dry liquid ND3 and subsequent removal of the solvent leads to the colourless microcrystalline powder of [Be(ND3)4]Cl2. It crystallises in the orthorhombic space group Pna21 with a = 9.395(4), b = 11.901(6), c = 6.761(3) A, V = 755.9(6) and Z = 4 at 27 °C, and a = 9.3736(8), b = 11.8162(12), c = 6.6596(6) A, V = 737.62(12) and Z = 4 at –269.6 °C. The structure contains the tetrahedral tetraammineberyllium(II) cation which follows the octet rule. It was shown to be stable under ambient conditions and temperatures up to approximately 175 °C. We additionally discuss the aid of solid-state quantum chemical calculations for the assignment of proper crystallographic space g…
Transforming food systems at local levels: using participatory system dynamics in an interactive manner to refine small-scale farmers’ mental models
2017
Food systems will need to undergo considerable transformation. To be better prepared for and resilient to uncertainty and disturbances in the future, resource users and managers need to further develop knowledge about the food and farming system, with its dominating feedback structures and complexities, and to test robust and integrated system-based solutions. This paper investigates how participatory system dynamics modeling can be adapted to groups at the community level with low or no formal educational background. The paper also analyses the refinement of workshop participants’ mental models as a consequence of a participatory system dynamics intervention. For this purpose, we ran two w…
A multicenter observational study on Medication-Related Osteonecrosis of the Jaw (MRONJ) in advanced cancer and myeloma patients of a cancer network …
2020
Background Incidence of Medication-Related Osteonecrosis of the Jaw (MRONJ) related to cancer and myeloma treatments is undetermined, with scarce data varying from 2 to 7.8/million/year in limited investigated populations. A 9-years [2009-2018] regional-wide survey was conducted, deploying the North-Western Italy Cancer Network (“Rete Oncologica Piemonte e Valle d’Aosta”), to assess number and main characteristics of MRONJ cases among myeloma/cancer patients, within a population of 4.5 million inhabitants. Material and Methods MRONJ cases were collected retrospectively from January 2009 to June 2015; from July 2015 to December 2018, data were collected prospectively. Number of new MRONJ cas…
A comprehensive study of structure and properties of nanocrystalline zinc peroxide
2022
Abstract Nanocrystalline zinc peroxide (nano-ZnO2) was synthesized through a hydrothermal process and comprehensively studied using several experimental techniques. Its crystal structure was characterized by X-ray diffraction, and the average crystallite size of 22 nm was estimated by Rietveld refinement. The temperature-dependent local environment around zinc atoms was reconstructed using reverse Monte Carlo (RMC) analysis from the Zn K-edge X-ray absorption spectra. The indirect band gap of about 4.6 eV was found using optical absorption spectroscopy. Lattice dynamics of nano-ZnO2 was studied by infrared and Raman spectroscopy. In situ Raman measurements indicate the stability of nano-ZnO…
X-ray Powder Structure Determination and Thermal Behavior of a New Modification of Pb(II) Selenite
2002
The crystal structure of a new polymorphic form of lead(II) selenite (PbSeO3) was solved directly from conventional X-ray powder diffraction data. Direct methods and Rietveld refinement techniques were used for the structure determination. The compound crystallizes in the monoclinic space group P21/c (no. 14) with cell dimensions a = 9.1587(1) A, b = 8.0902(1) A, c = 8.7932(1) A, β = 103.032(1)°, and V = 634.76(2) A3. The final refinement gave background excluded Rp = 6.22%, Rwp = 8.81%, and RB = 2.16% by using 45 structural and 15 profile parameters with 10 atoms in an asymmetric unit. The three-dimensional structure consists of 9-coordinated lead atoms, which are linked by three bidentate…
Large scale synthesis of nanostructured zirconia-based compounds from freeze-dried precursors
2013
Nanocrystalline zirconia powders have been obtained at the multigram scale by thermal decomposition of precursors resulting from the freeze-drying of aqueous acetic solutions. This technique has equally made possible to synthesize a variety of nanostructured yttria or scandia doped zirconia compositions. SEM images, as well as the analysis of the XRD patterns, show the nanoparticulated character of those solids obtained at low temperature, with typical particle size in the 10–15 nm range when prepared at 673 K. The presence of the monoclinic, the tetragonal or both phases depends on the temperature of the thermal treatment, the doping concentration and the nature of the dopant. In addition,…
Mn2+-induced room-temperature ferromagnetism and spin-glass behavior in hydrothermally grown Mn-doped ZnO nanorods
2014
The magnetic properties of Mn-doped ZnO (ZnO:Mn) nanorods grown by hydrothermal process at a temperature of 200 °C and a growth time of 3 h have been studied. The samples were characterized by using powder X-ray diffraction with Rietveld refinement, scanning electron microscopy, energy-dispersive X-ray analysis and SQUID magnetometry. Mn (3 wt%) and (5 wt%)-doped ZnO samples exhibit paramagnetic and ferromagnetic behavior, respectively, at room temperature. The spin-glass behavior is observed from the samples with respect to the decrease of temperature. At 10 K, both samples exhibit a hysteresis loop with relatively low coercivity. The room-temperature ferromagnetism in 5 wt% Mn-doped ZnO n…