Search results for "poros"
showing 10 items of 1076 documents
Development of a new peat-based oil sorbent using peat pyrolysis
2013
The growing use and transport of crude oil and oil products has led to increasing numbers of oil spillages of various scales. Oil sorbents have been extensively used for remediation of the consequences of such accidents. The aim of this study is to investigate the possible use of peat and its thermal treatment products for oil sorption. Peat as an oil sorbent has poor buoyancy characteristics, relatively low oil sorption capacity and low hydrophobicity. However, thermal treatment (low-temperature pyrolysis and synthesis of peat-based activated coal) helps to significantly improve its sorptive characteristics. Peat is a potential material for oil sorption because it has such advantages as lo…
An Ultrahigh CO2-Loaded Silicalite-1 Zeolite: Structural Stability and Physical Properties at High Pressures and Temperatures
2018
[EN] We report the formation of an ultrahigh CO2-loaded pure-SiO2, silicalite-1 structure at high pressure (0.7 GPa) from the interaction of empty zeolite and fluid CO, medium. The CO2-filled structure was characterized in situ by means of synchrotron powder X-ray diffraction. Rietveld refinements and Fourier recycling allowed the location of 16 guest carbon dioxide molecules per unit cell within the straight and sinusoidal channels of the porous framework to be analyzed. The complete filling of pores by CO, molecules favors structural stability under compression, avoiding pressure-induced amorphization below 20 GPa, and significantly reduces the compressibility of the system compared to th…
New insight into δ-Pu alloy oxidation kinetics highlighted by using in-situ X-ray diffraction coupled with an original Rietveld refinement method
2018
Abstract The reactivity of a δ-Pu alloy was studied under dry oxygen at different temperatures. Phase analysis has shown the presence of α-and β-Pu2O3, PuO2, as well as the destabilisation of the δ-phase. The oxidation kinetics were studied using in-situ X-ray diffraction coupled with an original method of Rietveld refinement enabling an individual monitoring of the growth of each oxide. The results have evidenced a parabolic stage resulting from the thickening of the α-Pu2O3 layer, in which a compressive stress state develops. This stage is followed by the linear growth of a porous PuO2 scale.
Linker depletion for missing cluster defects in non-UiO Metal-Organic Frameworks
2021
Defect engineering is a valuable tool to tune the properties of metal–organic frameworks. However, defect chemistry remains still predominantly limited to UiO-type MOFs. We describe the preferential formation of missing cluster defects in heterometallic titanium–organic frameworks of the MUV-10 family when synthesised in sub-stoichiometric linker conditions. Our results show the value of integrating experimental work, computational modelling and thorough characterization in rationalizing the impact of defects over the porosity and structure of this family of materials. Correlation of experiment with computational models reveals the dominance of missing cluster vacancies in the pore size dis…
Two Consecutive Magneto-Structural Gas-Solid Transformations in Non-Porous Molecular Materials
2018
Modification of the magnetic properties in a solid-state material upon external stimulus has attracted much attention in the recent years for their potential applications as switches and sensors. Within the field of coordination polymers, gas sorption studies typically focus on porous solids, with the gas molecules accommodating in the channels. Here we present a 1D non-porous coordination polymer capable of incorporating HCl gas molecules, which not only causes a reordering of its atoms in the solid state but also provokes dramatic changes in the magnetic behavior. Subsequently, a further solid-gas transformation can occur with the extrusion of HCl gas molecules causing a second structural…
A dynamic air–liquid interface system for in vitro mimicking of the nasal mucosa
2022
The development of an in vitro 3D model for the growth of the nasal mucosa cells can improve the therapy and the study of pathological states for subjects with chronic airway conditions. We have previously characterized a system consisting of a scaffold with an internal channel and a perfusion bioreactor with two independent flows provided by an external and an internal circuit, respectively. In this paper, this system was designed as a model of the nasal cavity, in which cells, grown on the inner surface of the scaffold channel, would be in contact at the same time with both culture medium, supplied by the external circuit, and air, provided with the internal flow. To ensure adequate nutri…
Il diritto come relazione comunicativa
2012
Da un punto di vista sociologico, il diritto può essere inteso come sistema informativo ed in particolare la norma non è altro che un atto di comunicazione, cioè un messaggio, avente particolari caratteristiche di descrittività e, in senso lato, di prescrittività. Un messaggio, cioè, che appare indirizzato a orientare azioni e aspettative d’azione. In questo senso, dunque, la norma conferisce senso e significato all’azione, in senso weberiano.
Mesoporous inorganic nanoscale particles for drug adsorption and controlled release.
2018
The review provides an overview of the mesoporous inorganic particles employed as drug delivery systems for controlled and sustained release of drugs. We have classified promising nanomaterials for drug delivery on the basis of their natural or synthetic origin. Nanoclays are available in different morphologies (nanotubes, nanoplates and nanofibers) and they are typically available at low cost from natural resources. The surface chemistry of nanoclays is versatile for targeted modifications to control loading and release properties. Synthetic nanomaterials (imogolite, laponite and mesoporous silica) present the advantages of well-established purity and availability with size features that …
Alendronate-related oral mucosa ulcerations
2000
Alendronate is widely used in the treatment of osteoporosis and other bone diseases. Although it is considered a well-tolerated drug, there are numerous reports of adverse effects on the mucosa in the upper aerodigestive tract, with oesophagitis as the most common complication. The strict regulations for the proper administration of the drug indicate that these side effects might well be the result of a direct, irritant mechanism on the upper aerodigestive tract. We present two clinical cases of patients who developed extensive palatal ulcers as a result of taking alendronate. We discuss possible mechanisms implicated in the production of the ulcers and some clinical factors of interest.
Mechanism of porous core electroosmotic pump flow injection system and its application to determination of chromium(VI) in waste-water.
1999
An electroosmotic pump flow injection system is introduced in this paper. According to electroosmotic theory, the pump's properties were described. A large flow range (mul min(-1)-ml min(-1)), moderate carrier pressure (0.15 MPa), reduced performance voltage (500 V) and stable flow rate (RSD3.0% in 4 h) are the main properties of the pump. NH(4)OH (0.35 mM) was used as carrier for improving the pump's flow stability. The electroosmotic efficiency of the pump's medium, porous core, can be recovered and regenerated. A sandwich zone was used for sample and reagent introduction in order to adapt to the pump performance. Flow injection-spectrophotometry was employed for the determination of Cr(V…