Search results for "materials engineering"
showing 10 items of 69 documents
The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud)
2016
AbstractWe present new data about the chemical and structural characteristics of bauxite residue (BR) from Greek Al industry, using a combination of microscopic, analytical, and spectroscopic techniques. SEM-EDS indicated a homogeneous dominant “Al-Fe-Ca-Ti-Si-Na-Cr matrix”, appearing at the microscale. The bulk chemical analyses showed considerable levels of Th (111 μg g−1), along with minor U (15 μg g−1), which are responsible for radioactivity (355 and 133 Bq kg−1 for 232Th and 238U, respectively) with a total dose rate of 295 nGy h−1. Leaching experiments, in conjunction with SF-ICP-MS, using Mediterranean seawater from Greece, indicated significant release of V, depending on S/L ratio,…
The Ferroelectric Photo-Groundstate of SrTiO$_3$: Cavity Materials Engineering
2021
Significance Controlling collective phenomena in quantum materials is a promising route toward engineering material properties on demand. Strong THz lasers have been successful at inducing ferroelectricity in S r T i O 3 . Here we demonstrate, from atomistic calculations, that cavity quantum vacuum fluctuations induce a change in the collective phase of S r T i O 3 in the strong light–matter coupling regime. Under these conditions, the ferroelectric phase is stabilized as the ground state, instead of the quantum paraelectric one. We conceptualize this light–matter hybrid state as a material photo ground state: Fundamental properties such as crystal structure, phonon frequencies, and the col…
How to reduce energy and water consumption in the preparation of raw materials for ceramic tile manufacturing: Dry versus wet route
2017
Abstract Dry and wet routes in the ceramic tile manufacturing process refer to two different technologies for preparing the raw materials for the forming stage. Both result in a granulated solid ready for use in the pressing stage, but with different characteristics. The dry route was the first to be developed. As quality standards and tile sizes increased, the wet route was developed and introduced successfully into the manufacturing process. Since 1990, the wet route has been the most used around the world to prepare ceramic tile body raw materials. The powder produced by the wet route has finer particles and higher flowability, which has allowed the production of higher quality ceramic t…
Protonation-induced fluorescence modulation of carbazole-based emitters
2022
The development of purely organic fluorescence emitters is of great importance for their low cost and high performance. Responding to this demand, carbazole is a promising emitter due to its extensive freedom for functionalisation, high thermal and chemical stability, as well as low cost. Herein, the effect of protonation on the fluorescence of various pyridine-functionalised carbazole-based bipolar host materials was studied both in solution and in the solid-state. The restriction of intramolecular rotation of the molecules upon protonation of the pyridyl-moiety together with easier planarization of the protonated acceptor and the donor moieties and relocalisation of the LUMO orbital on th…
Industrial Hemp Transformation for Composite Applications: Influence of Processing Parameters on the Fibre Properties
2017
The main objective of this collaborative work is to characterize the influence of the processing stages of industrial hemp on the fibre properties. Transformation processes well suited for composite reinforcing textiles are considered. The work focuses on the different stages along the transformation chain of hemp, from the straw retting to the preform manufacturing. The main highlight is the predominant influence of retting on the tensile properties of individual fibres after their mechanical extraction from the stalks. Regarding the secondary processing, different technologies such as spinning, and use of natural binder systems are also proposed to produce yarns and woven fabrics. The eff…
Ligand engineering in Cu(ii) paddle wheel metal–organic frameworks for enhanced semiconductivity
2020
We report the electronic structure of two metal-organic frameworks (MOFs) with copper paddle wheel nodes connected by a N2(C2H4)3 (DABCO) ligand with accessible nitrogen lone pairs. The coordination is predicted, from first-principles density functional theory, to enable electronic pathways that could facilitate charge carrier mobility. Calculated frontier crystal orbitals indicate extended electronic communication in DMOF-1, but not in MOF-649. This feature is confirmed by bandstructure calculations and effective masses of the valence band egde. We explain the origin of the frontier orbitals of both MOFs based on the energy and symmetry alignment of the underlying building blocks. The effe…
Interfacial Self-Assembly to Spatially Organize Graphene Oxide Into Hierarchical and Bioactive Structures
2020
Multicomponent self-assembly holds great promise for the generation of complex and functional biomaterials with hierarchical microstructure. Here, we describe the use of supramolecular co-assembly between an elastin-like recombinamer (ELR5) and a peptide amphiphile (PA) to organize graphene oxide (GO) flakes into bioactive structures across multiple scales. The process takes advantage of a reaction—diffusion mechanism to enable the incorporation and spatial organization of GO within multiple ELR5/PA layers. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ImageJ software were used to demonstrate the hierarchical organization of GO flakes within the ELR5/PA lay…
Benchmarking of strength models for unidirectional composites under longitudinal tension
2018
© 2018 Elsevier Ltd Several modelling approaches are available in the literature to predict longitudinal tensile failure of fibre-reinforced polymers. However, a systematic, blind and unbiased comparison between the predictions from the different models and against experimental data has never been performed. This paper presents a benchmarking exercise performed for three different models from the literature: (i) an analytical hierarchical scaling law for composite fibre bundles, (ii) direct numerical simulations of composite fibre bundles, and (iii) a multiscale finite-element simulation method. The results show that there are significant discrepancies between the predictions of the differe…
Use of new hydroxytelechelic cis-1,4-polyisoprene (HTPI) in the synthesis of polyurethanes (PUs): Influence of isocyanate and chain extender naturean…
2006
AbstractNew segmented polyurethanes (thermoplastic-elastomers) based on previously described hydroxytelechelic cis-1,4-polyisoprene (HTPI), miscellaneous isocyanates and chain extenders at various equivalent ratios were prepared by the classical one-shot method. The influence of the nature of isocyanate and chain extender, as well as their equivalent ratios, on the mechanical and thermal materials behavior was investigated. Thus, a comparative assessment of material properties was performed. Microphase separation of hard and soft segments was observed by DMTA, DSC and AFM. Moreover, according to Thermogravimetric Analysis (TGA), linear relationships depending on the isocyanate and chain ext…
Coating Toughness Estimation through a Laser Shock Testing in Ni-Cr-B-Si-C Coatings
2018
In the nuclear field, efforts are made to find substitutes to cobalt hardfacing alloys since these alloys have a principal drawback, the transmutation from stable 59Co to 60Co under neutron irradiation. In case of wear, fragments could be deposed on the surface of primary circuit and thus contaminate it, causing a real issue for deconstruction.