1,721,279 research outputs found
Editorial for special issue â New insights in stability, structure and properties of porous materialsâ
No full textFurfural (C5H4O2) encapsulation and release by ZSM-5 zeolite for sustainable treatment in agriculture
No full textAn overview of biopolymer-based nanocomposites for optics and electronics
No full textBiopolymer-based nanocomposites are materials composed mainly of biopolymer matrices in which nanofillers are dispersed. Biopolymers are polymers obtained from some living organisms; therefore they are biodegradable and biocompatible; moreover, they have a variety of functional groups allowing the control of the interface with nanofillers and the multiscale assembly. They have been employed in numerous applications also because of their flexibility under processing conditions and competitive cost of their end products. Most of the published work is focused on their electronic and biomedical applications. In this review we focus our attention on biopolymer-based composites with inorganic nanofillers like metal, metal oxides, semiconductor nanoparticles and carbon-based nanoparticles, for application in optics and electronics. Special attention is paid to synthesis strategies for integrating nanofillers in biopolymer matrices. This journal i
Toluene and n-hexane competitive adsorption on high-silica ZSM-5 zeolite
No full textFuel-based compounds, such as toluene and n-hexane, are common pollutants present in water and wastewater. Due
to their tendency to persist in air, water and soil and to bioaccumulate through the food chain, they are included among
the most hazardous compounds for human health and environment. Acquatic ecosystems are especially vulnerable
because of the frequent use of water bodies as recipients of potentially toxic liquids and solids from domestic,
agricultural and industrial wastes. Hence, the removal of fuel-based compounds, through adsorption onto inorganic
sorbents is of considerable interest. Due to their selectivity towards organic contaminant and fast adsorption kinetics, it
has been recently highlighted that High Silica Zeolites are hydrophobic sorbent materials suitable for adsorption
processes (Martucci et al., 2015; Pasti et al., 2016). The aim of this work is to determine the ZSM-5 zeolite degree of
selectivity and its structural changes when a competitive adsorption of toluene and n-hexane occurs. A sample of ZSM-
5 zeolite (MFI topology, SiO2/Al2O3 ratio=280), was provided by Tosoh Corporation and loaded with a binary mixture
of toluene and n-hexane. Kinetics and adsorption isotherm data were obtained via Headspace Solid Phase
Microextraction-GC. Powders patterns were collected before and after adsorption on a Bruker D8 Advance
diffractometer equipped with SOL-X detector. Thermal (TG and DTA) analysis were performed in air up to 900°C at
10°C/min. This multidisciplinary approach allowed us to: 1) measure the sorption capacity of zeolite materials weighed
against organic pollutants dissolved in water; 2) characterise the sorbent structure after pollutant adsorption; 3) localise
the organic species in the zeolite channel systems; 4) probe the interaction between the adsorbate and zeolite framework.
Rietveld refinements provide information about the relative position of molecules inside the structure after toluene, nhexane
and their mixture adsorption. Data reveal that 1) n-hexane and toluene are preferentially adsorbed whether as
single components than as binary mixture; 2) zeolite selectivity is higher towards the n-hexane than toluene. Differences
Fourier maps analysis shows that n-hexane, water, and toluene have been adsorbed at about 8.95%, 2.2%, and 1.59%,
respectively, in good agreement with both adsorption data and thermal analysis. As a matter of fact, ZSM-5 zeolite
preferably adsorbs n-hexane, even in presence of a competitor, such as toluene.
Martucci, A., Braschi, I., Bisio, C., Sarti, E., Rodeghero, E., Bagatin, R., Pasti, L. (2015): Influence of water on the retention of
methyl tertiary-butyl ether by high silica ZSM-5 and Y zeolites: a multidisciplinary study on the adsorption from liquid and gas
phase. RSC Adv., 5, 86997-87006.
Pasti, L., Rodeghero, E., Sarti, E., Bosi, V., Cavazzini, A., Bagatin, R., Martucci, A. (2016): Competitive adsorption of VOCs from
binary aqueous mixtures on zeolite ZSM-5. RSC Adv., 6, 54544-54552
La casa stampata. Le sperimentazioni di Gaetano Vinaccia per l'edilizia economica tra autarchia e ricostruzione
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Phase transformations and structural modifications induced by heating in microporous materials
No full textThe thermal behaviour of microporous materials is relevant both for their characterization and for their application, and varies dramatically from one material to another. This paper intends to give a picture of their behaviour and to highlight analogies and differences in these materials as a function of their chemistry and topology. The information on their response to heating and dehydration/calcinations, even if still scanty and sometimes controversial, shows that some materials undergo dehydration-induced decrease in volume, which can be dramatic or very scarce as a function of the extraframework content. These changes in volume can be partially or completely irreversible if they involve structural modifications of the tetrahedral framework. It is to highlight that topological changes are always due to the so called "face sharing tetrahedral" process
Location of 6-azonia-spiro- [5,5]-undecane molecules in ZSM-12 using X-ray synchrotron powder diffraction data
No full textHigh-silica ZSM-12 (MTW topology), synthesized with 6-azonia-spiro- (Rimer, 2018; Rimer, 2018) [5,5]-undecane as structure directing agent (SDA), was carefully characterized by using X-ray synchrotron powder diffraction. The structure refinement led to a monoclinic unit cell (space group Cc, Z = 4, a = 25.0814(13) Å, b = 15.0987(8) Å, c = 24.4419(17) Å, β = 107.844(6), V = 8810.8(8) Å3) with a three times enlargement of the unit cell along the b axis with respect to the calcined starting ZSM-12 (space group C2/c, Z = 1, a = 24.8633(3) Å, b = 5.01238(7) Å, c = 24.3275(7) Å, β = 107.7215(6)°). The SDAs conformation and position in the framework structure did not maintain the twofold axes coinciding with the crystallographic twofold axis thus changing the space group symmetry from C2/c to Cc. The structure refinement gave an extraframework content 6.13 SDA molecules per unit cell (corresponding to ~9.0 wt%) in good agreement with the weight loss given by the thermogravimetric analysis. The refined bond distances revealed the occurrence of non-bonding interactions of both azonia molecules with the MTW pore wall. AZO-1 and AZO-2 molecules are H-bonded between them thus forming clusters aligned along the b axis. This information is crucial to tailor the physicochemical properties of zeolites as well as to address their hydrophobicity, pore dimensions and cavities thus optimizing the selectivity of zeolite catalysts
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Evidence on neuroprotective properties of coenzyme Q10 in the treatment of glaucoma
No full textGlaucoma, the leading cause of visual impairment and irreversible blindness worldwide, is a multifactorial, progressive optic neuropathy characterized by loss of retinal ganglion cells, alterations of the optic nerve head, and specific visual field defects. Clinical evidence shows that intraocular pressure is the major risk factor of the treatable disease. However, in some patients, glaucoma develops and continues to progress despite normal intraocular pressure values, suggesting that other risk factors are involved in the disease. Consequently, neuroprotective treatments, focused on preventing retinal ganglion cells death by acting on different therapeutic strategies but not focused on intraocular pressure reduction, has therefore become of great interest. In this contest, coenzyme Q10, showing evidence in slowing or reversing pathological changes typical of the disease, has been proposed as a potential neuroprotective agent in glaucoma. In this review, we describe the possible mechanisms of action of coenzyme Q10 and the recent evidence in literature regarding the neuroprotective activity of the molecule
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