Search results for "Solid"

Applicability of solid state fast field cycling NMR relaxometry in understanding relaxation properties of leaves and leaf-litters

2011

Abstract Inversion recovery high field solid state (SS) 1H NMR spectroscopy and fast field cycling (FFC) NMR relaxometry have been applied on dried leaves and leaf-litters from a reafforestated area in central Sicily (Italy) in order to evaluate relaxation properties in both slow ( 1 ≪ ω 0 2 τ C 2 ) and fast ( 1 ≫ ω 0 2 τ C 2 ) motion regimes. Namely, SS 1H NMR spectroscopy (i.e. slow motion regime conditions) revealed that two relaxation components (a fast and a slow one) can be identified in all the leaves and leaf-litter samples. The fast component was assigned to small sized plant metabolites, whereas the slow one was attributed to slowly tumbling macropolymeric molecules. FFC NMR relax…

Comparing different processing methods in apple slice drying. Part 2 solid-state Fast Field Cycling 1H-NMR relaxation properties, shrinkage and chang…

2019

The objective of this paper was to study the effects of different drying methods that are: microwave (MW), hot air (HA) and a combination of both (HY), on the 1H-NMR relaxation properties, shrinkage and volatile compounds of Golden Delicious apple slices. Fast field cycling NMR relaxometry reveals that the HA samples dried at different temperatures (65 and 75 °C) appear to contain less restrained water as compared to the sample obtained by MW heating at the same temperatures. In fact, the longitudinal relaxation rates (T1) of the water molecules in the HA dried slices resulted shorter than those measured for the MW dried samples, thereby revealing that in the MW slices, water molecules beha…

Phases transitions in complexe oxides with perovskite structure : case system (1-x)Na0,5Bi0,5TiO3 - xCaTiO3

2015

The solid solutions (1-x)Na0,5Bi0,5TiO3 (NBT) – xCaTiO3 (CT) were studied by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, impedance spectroscopy and DSC. These materials have a perovskite crystalline structure. This study reveals not only the complexity but also the richness of physical phenomena in these compounds: phases transitions sequences, the Ca2+ effect on the physical-chemistry properties and the relation between dielectric properties and crystalline structure. Thereby, (1-x)NBT – xCT solid solutions (0 ≤ x ≤ 1.00) were synthesized by chemical solid route, then they were sintered by a particular procedure in order to avoid sodium and bismuth volatilization. …

Evaluation of the fuel potential of sewage sludge mixtures with beech sawdust and lignite

2018

Sewage sludge (SS) from municipal wastewater treatment has drawn serious attention of scientists around the world in the attempt to find feasible disposal methods. Therefore, in this work, a solution for valorisation of SS as solid fuel is proposed based on an advanced compositional investigation of SS versus conventional solid fuels, namely, lignite (L) and beech sawdust (BS). A characterisation in terms of proximate analysis and ultimate analysis was performed for the studied materials, both to SS, L, and BS as single fuel and to bi-component mixture formulas of SS and L/BS, in variable proportions of 30:70, 50:50, and 70:30. SS:BS based blends had higher hydrogen (from 4.43 wt. % to 5.14…

Ab initio modelling of oxygen vacancies and protonic defects in La1−xSrxFeO3−δ perovskite solid solutions

2016

Using hybrid density functionals, detailed ab initio calculations were performed for oxygen vacancies and protons in La1−xSrxFeO3−δ perovskite solid solutions which may serve as a cathode material in protonic ceramic fuel cells. The atomic and electronic structures of different configurations of defects and the role of Fe oxidation state are analyzed in detail. The energetics of the reduction and hydration reactions are investigated. The hydration energy is found to be significantly smaller than for Ba(Zr1−xYx)O3−x/2 electrolyte materials, and the role of basicity as one decisive factor is discussed.

First-principles modelling of complex perovskite (Ba1-xSrx)(Co1-yFey)O3-δ for solid oxide fuel cell and gas separation membrane applications

2010

The results of the first principles spin-polarized DFT calculations of the atomic and electronic structure of a complex perovskite (Ba1-xSrx)(Co1-yFey)O3-δ (BSCF) used as a cathode material for solid oxide fuel cells (SOFC) and gas separation membranes are presented and discussed. The formation energies of oxygen vacancies are found to be considerably smaller than in other magnetic perovskites, e.g. (La,Sr)MnO3, which explains the experimentally observed strong deviation of this material from stoichiometry. The presence of oxygen vacancies induces a local charge redistribution, associated with the local lattice perturbation, and expansion of the equilibrium volume, in line with the experime…

Torrefaction technology for solid fuel production

2011

Johannesburgo, entre el escapismo y la estafa

2002

Quality of reporting in abstracts of RCTs published in emergency medicine journals: a protocol for a systematic survey of the literature

2017

Introduction The quality of reporting of abstracts of randomised controlled trials (RCTs) in major general medical journals and in some category-specific journals was shown to be poor before the publication of the ConsolidatedStandards of ReportingTrials (CONSORT) extension for abstracts in 2008, and an improvement in the quality of reporting of abstracts was observed after its publication. The effect of the publication of the CONSORT extension for abstracts on the quality of reporting of RCTs in emergency medicine journals has not been studied. In this paper, we present the protocol of a systematic survey of the literature, aimed at assessing the quality of reporting in abstracts of RCTs p…

Cluster-Randomized Studies.

2018

Background Cluster-randomized trials (CRT) are needed to compare interventions that are allocated to entire groups of subjects, rather than to individuals. Publications about CRT have become steadily more common over the past decade. Readers of such publications should be able to categorize and interpret the findings of CRT correctly while considering the methodological requirements applicable to this type of study. Methods This review is based on a selection of pertinent literature and on the authors' expertise. CRT-specific methodological aspects of the planning, performance, and interpretation of studies are discussed. Results Readers of publications on CRT should check whether due consi…