Search results for " Porosity"
showing 10 items of 31 documents
Porosity effects on elastic properties of polycrystalline materials: a three-dimensional grain boundary formulation
2013
Polycrystalline materials are widely used in many technological applications of engineering interest. They constitute an important class of heterogeneous materials, and the investigation of the link between their macro and micro properties, main task of the micromechanics [1], is of relevant technological concern. The internal structure of a polycrystalline material is determined by the size and the shape of the grains, by their crystallographic orientation and by different type of defects within them. In this sense, the presence of internal voids, pores, is important to take into account in the determination of the polycrystalline aggregate properties. Porosity exists in almost all materia…
Polycrystalline materials with pores: effective properties through a boundary element homogenization scheme
2014
In this study, the influence of porosity on the elastic effective properties of polycrystalline materials is investigated using a formulation built on a boundary integral representation of the elastic problem for the grains, which are modeled as 3D linearly elastic orthotropic domains with arbitrary spatial orientation. The artificial polycrystalline morphology is represented using 3D Voronoi tessellations. The formulation is expressed in terms of intergranular fields, namely displacements and tractions that play an important role in polycrystalline micromechanics. The continuity of the aggregate is enforced through suitable intergranular conditions. The effective material properties are ob…
Nitroarene hydrogenation catalysts based on Pd nanoparticles glued with PDA on inorganic supports: Multivariate Curve Resolution as an useful tool to…
2021
[EN] Two green catalysts based on Pd(0) nanoparticles (Pd NPs) anchored through PDA on porous silica and magnetite have been synthesized using a generalized simple and reproducible "two-step" methodology. Both catalysts were tested for a model reaction, the hydrogenation of 4-nitrophenol using NaBH4 as the hydrogenating agent, and especially good activity has been achieved in the case of the catalysts containing magnetite as inorganic core (Pd NPs-PDA@Fe3O4). We analyzed the effect associated with the catalyst separation method (centrifugation or magnetically) that affect to the distribution and aggregation degree of the Pd NPs. In addition, we also correlate the final catalyst morphology w…
Laboratory tests addressed to realize customized restoration procedures of underwater archaeological ceramic finds
2013
The present contribution is part of a biennial research project funded by the Italian Ministry of Education, Universities and Research (MIUR). This study, currently in progress, deals with innovative experimental approaches applied to the chemical, mineralogical and physical transformations occurring during the prolonged permanence of archaeological ceramic finds in seawater environments as well as to restoration and conservation issues of the same underwater artifacts. The experimental approach used in this research consisted in the manufacture of ceramic test-pieces (briquettes) and their successive placing in underwater environment. This work aims at assessing how textural and compositio…
Comparison between mercury intrusion porosimetry and nuclear magnetic resonance relaxometry to study the pore size distribution of limestones treated…
2019
Abstract Pore-space properties, such as pore-size distribution and connected porosity, are relevant factors in the evaluation of the performance of a consolidation treatment. In this study, two different techniques – Mercury Intrusion Porosimetry (MIP) and Nuclear Magnetic Resonance Relaxometry (NMRR) – were adopted to study the compatibility and the efficacy of a new consolidation product for limestones. This work aims at comparing and combining data obtained by MIP and NMRR; to confirm the relationship between the quantitative results of MIP and the qualitative ones of NMRR, a calibration which leads to correlate T2 distribution and pore size distribution has been applied. Experimental re…
Fate of aerobic granular sludge in the long-term: The role of EPSs on the clogging of granular sludge porosity
2016
This work aims to investigate the stability of aerobic granular sludge in the long term, focusing on the clogging of the granular sludge porosity exerted by the extracellular polymeric substances (EPSs). The effects of different cycle lengths (short and long-term cycle) on the granular sludge stability were investigated. Results obtained outlined that during the short duration cycle, the formation and breakage of the aerobic granules were continuously observed. During this period, the excess of EPS production contributed to the clogging of the granules porosity, causing their breakage in the long run. During the long-duration cycle, the extended famine period entailed a greater EPSs consump…
Assessing the Effects of VEGF Releasing Microspheres on the Angiogenic and Foreign Body Response to a 3D Printed Silicone-Based Macroencapsulation De…
2021
Macroencapsulation systems have been developed to improve islet cell transplantation but can induce a foreign body response (FBR). The development of neovascularization adjacent to the device is vital for the survival of encapsulated islets and is a limitation for long-term device success. Previously we developed additive manufactured multi-scale porosity implants, which demonstrated a 2.5-fold increase in tissue vascularity and integration surrounding the implant when compared to a non-textured implant. In parallel to this, we have developed poly(ε-caprolactone-PEG-ε-caprolactone)-b-poly(L-lactide) multiblock copolymer microspheres containing VEGF, which exhibited continued release of bioa…
ChemInform Abstract: Environmental NMR: Fast-Field-Cycling Relaxometry
2016
Fast-field-cycling (FFC) NMR relaxometry deals with the variation of the spin–lattice relaxation times (T1) in a complex system, as the strength of the applied magnetic field is changed. Information about molecular dynamics can be achieved. Until now, only model theories for FFC NMR relaxometry have been developed for polymer and material sciences. Just a few applications have been performed in the environmental sciences. These mainly deal with soil porosity, rock permeability, biomass transformations, and natural organic matter dynamics. Further, FFC NMR relaxometry can also be applied to monitor the environmental fate of contaminants, to understand the dynamics of nutrients at the soil–pl…
Environmental NMR: Fast-field-cycling Relaxometry
1996
Fast-field-cycling (FFC) NMR relaxometry deals with the variation of the spin–lattice relaxation times (T1) in a complex system, as the strength of the applied magnetic field is changed. Information about molecular dynamics can be achieved. Until now, only model theories for FFC NMR relaxometry have been developed for polymer and material sciences. Just a few applications have been performed in the environmental sciences. These mainly deal with soil porosity, rock permeability, biomass transformations, and natural organic matter dynamics. Further, FFC NMR relaxometry can also be applied to monitor the environmental fate of contaminants, to understand the dynamics of nutrients at the soil–pl…