Search results for "poros"
showing 10 items of 1076 documents
The role of fouling mechanisms in a membrane bioreactor.
2007
The present study has aimed to quantify the role of pore blocking and cake layer in a laboratory scale hollow fibre membrane module in submerged configuration. The membrane reactor (MBR) was fed with raw wastewater, only screened with a 2-mm sieve, collected from the Palermo WWTP. The MBR was characterised by an operating volume of 190 L and equipped with an aeration system located on the bottom of the reactor. The MBR operated for 65 days. The permeate was extracted by imposing a constant flux through the membrane (21 Lh−1m−2). The results confirm the importance of pore blocking control during start-up. In particular, it provides a rapid irreversible fouling that takes place at the beginni…
Design, characterization and comparison of materials based on β and γ cyclodextrin covalently connected to microporous silica for environmental analy…
2018
Abstract Determination of organic pollutants in environmental samples presents great difficulties due to the lack of sensitivity and selectivity in many of the existing analytical methods. In this work, the efficiency of materials based on silica structures containing bounded γ-cyclodextrin has been evaluated to determinate phenolic compounds and polycyclic aromatic hydrocarbons in air and water samples, respectively, in comparison with materials made of β-cyclodextrin. According to the results obtained for the material characterization, the new γ-cyclodextrin solid phase does not apparently present any porosity when used in air samples, but it has been shown to work efficiently for the pre…
Investigation of the noble gas solubility in H2O–CO2 bearing silicate liquids at moderate pressure II: the extended ionic porosity (EIP) model
2000
A semi-theoretical model is proposed to predict partitioning of noble gases between any silicate liquid and a H2O–CO2 gas phase with noble gas as a minor component, in a large range of pressures (at least up to 300 MPa). The model is based on the relationship between the concentration of dissolved noble gas and ionic porosity of the melt, found by Carroll and Stolper [Geochim. Cosmochim. Acta 57 (1993) 5039–5051] for H2O–CO2 free melts. It evaluates the effect of dissolved H2O and CO2 on the melt ionic porosity and, consequently on Henry’s constants of noble gases. The fugacities of the noble gases in the H2O–CO2–noble gas mixtures are also considered in our equilibrium calculations of diss…
Sol–gel material as a support of organometallic catalyst for ethylene polymerization
2008
Abstract The sol–gel procedure was applied to obtain powdery materials with different structures and morphology. It was possible to produce almost non-porous silica powder, with an extremely low surface area (ca. 4 m 2 /g) and very high uniformity of spherical particles as well as materials with various uniformity of particles and different porosity, most likely associated with increasing pore volume. Dependent on the properties of the carrier, the resulting supported vanadium catalysts (VOCl 3 /AlEt 2 Cl) showed significant differences concerning activity and stability. It was confirmed that improved hydrophobicity of the carrier’s surface may be useful and improve the activity of the syst…
Evanescent wave-initiated photopolymerisation as a new way to create monolithic open-tubular capillary columns: use as enzymatic microreactor for on-…
2010
Evanescent wave-initiated photopolymerisation in an optically wave guiding PTFE-coated fused silica capillary using light-emitting diode as a light source, is established here as a way to fabricate monolithic porous layer open-tubular capillary columns with a potential in capillary separation methods; application of the obtained open-tubular columns as enzymatic microreactors for on-line protein digestion is demonstrated.
Activité physique et prévention des chutes chez les personnes âgées
2015
Les chutes chez les personnes âgées sont fréquentes : près d’une personne de plus de 65 ans sur trois et une personne de plus de 80 ans sur deux chutent chaque année. L’état de santé, les capacités fonctionnelles, les facteurs comportementaux ou les caractéristiques de l’environnement constituent autant de facteurs de risque. Au-delà des traumatismes physiques et psychologiques tels que la peur de tomber qui en résultent, les chutes peuvent entraîner des limitations fonctionnelles, une diminution de la qualité de vie, une perte d’autonomie voire une entrée en institution.Dans un contexte de vieillissement de la population, la prévention des chutes et la préservation de l’autonomie dans les …
Effects of Three Interventions Combining Impact or Walking at Intense Pace Training, with or without Calcium and Vitamin Supplements, to Manage Postm…
2022
The purpose was to assess the effects of three interventions on bone mineral density (BMD) to prevent the onset or progression of osteoporosis in postmenopausal women. Specifically, thirty-nine postmenopausal women, diagnosed with osteopenia or osteoporosis, implemented either high-impact training (G1), the same training + calcium and vitamin D intake (G2), or walked at an intense pace + calcium and vitamin D (G3). Baseline change (BC) in BMD was estimated using the femoral neck and lumbar spine T-scores. Participants were classified as having suffered fractures and/or falls before (24-month) and during the 2-year intervention. The participants—aged 61.8 years—were allocated int…
Highly-sensitive anisotropic porous silicon based optical sensors
2012
The modeling, fabrication and characterization of PSi fabricated from both (110) and (100) surface oriented silicon for optical sensing is thoroughly reported. First, based on the generalized Bruggeman method, the birefringence and sensitivity of the fabricated membranes were calculated as a function of the fabrication parameters such as porosity and pore sizes; and external effects, such as the pores surface oxidation. Thereafter we report on the fabrication of PSi membranes from (110) and (100) surface oriented silicon with pore sizes in the range of 50 - 80 nm, and the characterization of their birefringence using a polarimetric setup. Their sensitivities were determined by filling the p…
A water-soluble hexa-peri-hexabenzocoronene: synthesis, self-assembly and role as template for porous silica with aligned nanochannels
2005
A water-soluble hexa-peri-hexabenzocoronene was prepared and shown to undergo ordered columnar self-assembly either in water solution or bulk and therefore served as template for the fabrication of porous silica with aligned nanochannels.
Bottom‐Up Fabrication of Semiconductive Metal-Organic Framework Ultrathin Films
2018
Though generally considered insulating, recent progress on the discovery of conductive porous metal-organic frameworks (MOFs) offers new opportunities for their integration as electroactive components in electronic devices. Compared to classical semiconductors, these metal-organic hybrids combine the crystallinity of inorganic materials with easier chemical functionalization and processability. Still, future development depends on the ability to produce high-quality films with fine control over their orientation, crystallinity, homogeneity, and thickness. Here self-assembled monolayer substrate modification and bottom-up techniques are used to produce preferentially oriented, ultrathin, con…