Search results for "Microstructure"

On the volumetric response of a compacted clay subjected to wetting and drying cycles

2009

Experimental evidence on the volumetric response of a compacted clay was collected in controlled suction oedometric tests, with the aim to assess the volumetric response of this soil when subjected to wetting and drying cycles. The overall soil behaviour seems mainly to depend on the double structural arrangement observed in the compacted specimens. Selected results are presented and discussed focusing on the influence of the stress history on the volumetric response. Test results are simulated by a double-structure suction-dependent elasto-plastic constitutive model, in which the mechanical response is related to micro and macrostructural deformations and their mutual interactions. The pro…

How does composition of model cheeses affect sodium and aroma release?

2011

International audience

Luminescence properties of neodymium-doped yttrium aluminium garnet obtained by the co-precipitation method combined with the mechanical process

2005

Nanopowders of yttrium aluminium garnet Y3Al5O12 (YAG) doped with neodymium ions were obtained by the co-precipitation method from the reaction of aluminium and yttrium nitrate and neodymium oxide with ammonia. After washing and drying the hydroxide precursors were calcined at 500, 700, 800 and 900 °C for 1 hour and at 1000 °C for 3 hours. This product was treated by ball milling in a zirconia vial for 0.5, 1.5 and 10 h in order to achieve smaller nanoparticles. The structure, microstructure, morphology and optical properties were investigated by means of diffractometric, microscopic and spectroscopic techniques. The course of the amorphous-to-crystalline transformation was complete after c…

Narratives of children with high-functioning autism spectrum disorder: A meta-analysis

2016

Abstract Background The aim of this meta-analysis was to analyze the narrative performance of children and adolescents with high-functioning Autism Spectrum Disorders (ASD) in terms of microstructure, macrostructure and internal state language. Method A systematic literature search yielded 24 studies that met the predetermined inclusion criteria. Effect sizes for each study were calculated for eight variables and analyzed using a random effects model. Intellectual ability, age and type of narrative were considered as potential moderators. Results Results revealed that the children with ASD performed significantly worse than their peers on all the variables considered. Conclusions Findings a…

Evolution of microstructure and related optical properties of ZnO grown by atomic layer deposition.

2013

A study of transmittance and photoluminescence spectra on the growth of oxygen-rich ultra-thin ZnO films prepared by atomic layer deposition is reported. The structural transition from an amorphous to a polycrystalline state is observed upon increasing the thickness. The unusual behavior of the energy gap with thickness reflected by optical properties is attributed to the improvement of the crystalline structure resulting from a decreasing concentration of point defects at the growth of grains. The spectra of UV and visible photoluminescence emissions correspond to transitions near the band-edge and defect-related transitions. Additional emissions were observed from band-tail states near th…

Synteza bimetalicznego silseskwioksanowego kompleksu tytanu(IV) i jego polimerycznego odpowiednika oraz ich właściwości katalityczne w polimeryzacji …

2016

Zsyntetyzowano, a następnie scharakteryzowano dwa tytanosilseskwioksany: nowy, nieznany dotąd z literatury, tetrachloroditytanosilseskwioksan (2) i jego polimeryczny odpowiednik (3). Zbadano właściwości katalityczne otrzymanych związków w polimeryzacji etylenu i 1-oktenu. Obydwa prekatalizatory, po aktywacji za pomocą Et2AlCl lub EtAlCl2, katalizują polimeryzację etylenu do polietylenu (PE) o małej masie molowej, która zmniejsza się zarówno ze wzrostem temperatury reakcji, jak i stosunku molowego Al:Ti. Kompleks (2) w połączeniu z metyloaluminoksanem lub związkami boru jest także aktywny w polimeryzacji 1-oktenu.

Synthesis and catalytic properties for olefin polymerization of new vanadium complexes containing silsesquioxane ligands with different denticity

2017

A series of new vanadium-silsesquioxanes (2a − 2d) was prepared by reacting VCl4 with not fully condensed silsesquioxanes (having from one to four silanol groups) and evaluated as pre-catalysts in olefin polymerization. The activation of 2a − 2d with EtAlCl2 generated highly active catalysts for ethylene polymerization, yielding high molar mass polymers with narrow dispersity. Ultra-high molar mass polyethylenes, Mw up to 4 × 106 g mol−1, were obtained with methylaluminoxane and Al(iBu)3/[Ph3C][B(C6F5)4] as activators. Upon treatment with methylaluminoxane and boron compounds, all vanadium pre-catalysts were active in 1-octene polymerization as well, and produced isotactic-rich poly(1-octen…

Influence of the microstructure on the durability of hard coatings obtained from metal powders

2016

Influence of the process parameters on the microstructure of a hardfacing coating elaborated by hot isostatic pressing

2019

Hot Isostatic Pressing elaboration of Norem02, an austenitic-ferritic hypereutectoid stainless steel, leads to the formation ofan austenitic matrix with a mixture of acicular M7C 3 and globular M23 C 6 carbides. The sintering tests, carried out by using an AISI304L container, showed that the final microstructure and the carbides’ distribution of the HIPed Norem02 are strongly influencedby the process parameters (heating and cooling rate, sintering time, holding temperature and pressure) and by the particles’ size,microstructure and phase distribution of the initial powder. The morphological, crystallographic and chemical analysis of the sinteredsamples were completed by comprehension of the…

On the effects of suitably designed space microstructures in the propagation of waves in time modulated composites

2023

In the one-dimensional case, the amplitude of a pulse that propagates in a homogeneous material whose properties are instantaneously changed in time will undergo an exponential increase due to the interference between the reflected and transmitted pulses generated at each sudden switch. Here, we resolve the issue by designing suitable reciprocal PT-symmetric space-time microstructures so that the interference between the scattered waves is such that the overall amplitude of the wave will be constant in time in each constituent material. Remarkably, for the geometries proposed here, a pulse will propagate with constant amplitude regardless of the impedance between the constituent materials,…