Search results for "Solid"
showing 10 items of 3575 documents
Glass Transition and Food Technology: A Critical Appraisal
2002
ABSTRACT: Most low water content or frozen food products are partly or fully amorphous. This review will discuss the extent to which it is possible to understand and predict their behavior during processing and storage, on the basis of glass transition temperature values (Tg) and phenomena related to glass transition. Two main conclusions are provisionally proposed. Firstly, glass transition cannot be considered as an absolute threshold for molecular mobility. Transport of water and other small molecules takes place even in the glassy state at a significant rate, resulting in effective exchange of water in multi-domains foods or sensitivity to oxidation of encapsulated materials. Texture pr…
Self-Assembly of a Copper(II)-Based Metallosupramolecular Hexagon
2008
The self-assembly of a 1:1 mixture of copper(II) ions and a rigid heteroditopic ligand L containing phen and terpy binding units gives rise in the solid state to green crystals of a hexanuclear metallamacrocycle 1. X-ray crystallography reveals that 1 consists of molecular hexagons of the grid-type family in which each metal ion is bound to two different ligands through the phen and terpy units, plus a weakly coordinated PF6 (-) anion in a highly distorted octahedral geometry. ES-MS studies of acetonitrile solutions of L and copper(II) in a 1:1 ratio show mixtures of polynuclear complexes in which trinuclear L3Cu3 species are predominant.
Sky-Blue Luminescent Au(I)-Ag(I) Alkynyl-Phosphine Clusters
2013
Treatment of the (AuC2R)n acetylides with phosphine ligand 1,4-bis(diphenylphosphino)butane (PbuP) and Ag(+) ions results in self-assembly of the heterobimetallic clusters of three structural types depending on the nature of the alkynyl group. The hexadecanuclear complex [Au12Ag4(C2R)12(PbuP)6](4+) (1) is formed for R = Ph, and the octanuclear species [Au6Ag2(C2R)6(PbuP)3](2+) adopting two structural arrangements in the solid state were found for the aliphatic alkynes (R = Bu(t) (2), 2-propanolyl (3), 1-cyclohexanolyl (4), diphenylmethanolyl (5), 2-borneolyl (6)). The structures of the compounds 1-4 and 6 were determined by single crystal X-ray diffraction analysis. The NMR spectroscopic st…
Determination of the stoichiometry of mixed microcrystals K x Cs y ZnCl 4 using instrumental neutron activation analysis
1998
Instrumental neutron activation analysis (INAA) has been employed as an absolute method for the determination of the stoichiometry of mixed microcrystals KxCsyZnCl4 with a weight ranging between 20 and 50 μg. The reliability of the method has been checked with the pure substances KCl, NaCl, CsCl and RbCl, for which the mean value of the ratio Cl/X was found to be 1.04 (3).
Kinetics of nitrogen removal in a MBR nutrient removal activated sludge system
2006
The application of membrane bioreactor (MBR) technology to biological nutrient removal (BNR) activated sludge (AS) systems is limited and uncertainty exists as to the impact of the conditions induced by the membranes on the biologically mediated processes of nutrient removal. Two main conditions associated with MBRs are (1) high total suspended solids (TSS) concentrations (8–20 g/L) and (2) different selection pressures due to biomass retention not being based on settleability, compared with conventional systems with secondary settling tanks (SSTs). Recently, Ramphao et al. [1] concluded that incorporating membranes in BNR AS makes a profound difference to the design of the system. Previous…
Non-exponential relaxation in disordered materials: Phenomenological correlations and spectrally selective experiments
1998
Abstract In most glass-forming materials external perturbations are relaxed in a non-exponential fashion. It is shown that the degree of non-exponentiality is phenomenologically correlated with the departure from simple thermally activated behavior as measured by the fragility index m. In model glass formers such as the Ge-As-Se ternary alloy, and to some degree for amorphous materials in general, the correlations with these properties are observed also for other characteristic features. These include the specific heat step and the aging kinetics in the glass transformation range. While phenomenological correlations have proven very useful for rationalizing the properties of many glass form…
More insight into characterization of the waterlogged wooden part of Acqualadroni Roman Rostrum by solid-state NMR
2016
Abstract Solid-state NMR spectroscopy was applied to characterize the wooden part of a roman Rostrum recovered in the Tyrrhenian Sea in the Acqualadroni area (Messina, Italy). The Acqualadroni Rostrum has been, in the recent past, investigated to establish its provenance and conservation. In this paper, solid-state NMR was used to obtain information on the conservation state of the wood as a preliminary step for the conservation process. A wooden sample of this artifact, collected by coring, was divided in four parts in order to correlate the conservation state to the depth. Results were compared with those obtained for a modern wood of the same species. A structural study was performed by …
Formation, structure and reactivity of boryloxycarbyne complexes of group 6 metals.
2003
Reaction of the diborane(4) B(2)(NMe(2))(2)I(2) with two equivalents of K[(eta(5)-C(5)H(5))M(CO)(3)] (M=Cr, Mo, W) yielded the dinuclear boryloxycarbyne complexes [[(eta(5)-C(5)H(5))(OC)(2)M(triple bond)CO](2)B(2)(NMe(2))(2)] (4 a, M=Mo; b, M=W; c, M=Cr), which were fully characterised in solution by multinuclear NMR methods. The Mo and W complexes 4 a, b proved to be kinetically favoured products of this reaction and underwent quantitative rearrangement in solution to afford the complexes [[(eta(5)-C(5)H(5))(OC)(2)M(triple bond)CO]B(NMe(2))B(NMe(2))[M(CO)(3)(eta(5)-C(5)H(5))]] (5 a, M=Mo; b, M=W); 5 a was characterised by X-ray crystallography in the solid state. Corresponding reactions of…
Crystalline self-assembly induced by aromatic edge-to-face interactions: the crystal structure of 2,6,6,10-tetrabenzyl-2,10-diaza-6-azonia[11]paracyc…
2002
The crystal structure of 2,6,6,10-tetrabenzyl-2,10-diaza-6-azonia[11]paracyclophane bromide reveals several intermolecular aromatic edge-to-face interactions which are important in the three-dimensional growing of the crystalline structure. Molecular dynamics and semiempirical studies indicate that the conformer found in the crystal is not the most stable in solution confirming the important role that edge-to-face interactions play in the structural arrangement found in the solid state.