•Boron and/or nitrogen-doped TiO2 for photocatalytic wastewater treatment.•Methyl red degradation/mineralisation as a function of pH, acids and dopants.•Adsorption time influence on photocatalytic ...process.•Recovery of worn-out catalyst.
Nowadays the employment of renewable and sustainable energy sources, and solar light as main option, becomes an urgent need. Photocatalytic processes received great attention in wastewater treatment due to their cheapness, environmental compatibility and optimal performances. Despite the general low selectivity of the photocatalysts, an accurate optimisation of the operational parameters needs to be carried out in order to maximise the process yield. Because of this reason, the present contribution aims to deepen either the knowledge in boron and/or nitrogen doped TiO2-based systems and their employment in methyl red removal from aqueous solutions. The samples were obtained by coprecipitation and characterised by XRD, SEM, BET specific surface area, UV–vis and XPS techniques. The catalytic activity was for the first time carefully evaluated with respect to methyl red photodegradation in different conditions as a function of working pH, counter-ions and pre-adsorption time. An ad-hoc study was performed on the importance of the pre-adsorption of the dye, suggesting that an extended adsorption is useless for the catalyst photoactivity, while a partial coverage is preferable. The photocatalytic tests demonstrate the positive influence of boron doping in photo-activated reactions and the great importance of the operational parameters with respect to the simple methyl red bleaching rather than the overall pollutant mineralisation. It is proved, indeed, that different working pH, acidifying means and substrate pre-adsorption time can enhance or limit the catalyst performances with respect to the complete pollutant degradation rather than its partial breakage.
•We propose an evidence-based approach for developing an agent-based simulation tool.•The approach is exemplified in a pedestrian crossing scenario in which a video-recorded observation was ...performed.•Results focus on traffic volumes, Level of Service, drivers’ compliance, crossing decisions.•Crossing behaviour is composed of three phases: approaching, appraising and crossing.•Analyses highlighted and quantified significant differences among adult and elderly pedestrians.
The modelling and simulation of pedestrian-vehicle interactions is an open challenge for both research and practical computational solutions aiming at supporting urban/traffic decision makers and managers. The social cost of pedestrian-car accidents pushes the development of more effective and expressive computational models and simulation systems, integrating analytical knowledge, data and experience about pedestrian-vehicle interactions. The paper presents the results of a significant data gathering campaign focused on the considered phenomenon and aimed at supporting the extension and calibration of an existing model. A video-recorded naturalistic observation was executed in an area of the City of Milan (Italy) characterized by a significant presence of elderly inhabitants and by a high number of road accidents involving pedestrians in the past years. The achieved results include both macroscopic and microscopic indicators about pedestrian-vehicle interactions at the observed non-signalized intersection, with reference to: (i) traffic volumes; (ii) Level of Service; (iii) drivers compliance to pedestrians right of way on zebra crossing; (iv) age-driven pedestrian crossing behaviour, focusing on motor skills (speeds and trajectories) and decision making (accepted time gap to cross). Since elderlies represent one of the most vulnerable pedestrians in terms of road accidents, data analysis is focused on comparing results among two samples composed of adults and aged pedestrians. Results showed that crossing behaviour is characterized by three main phases: approaching, appraising (evaluation of the distance and speed of oncoming vehicles) and crossing. Moreover, results showed a significant difference in the crossing behaviour of adult and elderly pedestrians. The final objective of the research is to support the development of a microscopic agent-based tool for simulating pedestrian-vehicle interactions at non-signalized crosswalks.
Thin films of MgO are grown by CVD, with a high growth rate, on Si(001) and quartz substrates in the temperature range 400–550 °C, using bis(methylcyclopentadienyl)magnesium Mg(CH3‐C5H4)2 as the ...precursor. The films obtained are investigated by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and optical absorption, in order to investigate the interrelations between film properties and processing conditions. Cubic phase MgO (periclase) films, characterized by a low carbon contamination and a granular surface morphology, are obtained.
Magnesium oxide thin films are grown by MOCVD in the temperature range 400–550 °C using bis(methylcyclopentadienyl)magnesium as precursor, which yields a high growth rate (up to 50 nm/min at 450 °C). The films, characterized by XRD, XPS and AFM analyses, contain the cubic MgO phase (periclase), with carbon contamination limited to the outermost layers and a granular surface morphology with low roughness values.
•Design of new environmentally-friendly fillers for innovative multifunctional coatings.•Successful encapsulation of usnic acid and zosteric acid sodium salt in two silica nanosystems.•Antifouling ...tests of the nanosystems against microorganisms from biological patinas colonising the Aurelian Walls in Rome.
In cultural heritage field, significant research efforts have been recently made to improve the efficacy of anti-vegetative treatments and to reduce the environmental impact caused by biocides high concentration. According to the pro-ecological approach, this work reports a novel approach based on the encapsulation/incorporation of environmentally-friendly biocides in different silica nanosystems in order to control the development of biological patinas on outdoor cultural heritage. Two different green biocides have been selected and tested in silica nanosystems: the zosteric acid sodium salt (ZS), a natural antifoulant compound produced by Zostera marina (eelgrass), and the usnic acid (UA), a secondary metabolite produced by some saxicolous lichens. ZS was previously successfully encapsulated but never entrapped in mesoporous silica; instead, UA is, for the first time, encapsulated and in situ entrapped into the silica nanosystems in order to control the release over time. Both silica nanosystems have been characterized as far as their dimensions and superficial properties and loading capability. The antifouling activity was assessed against microorganisms from biopatinas colonising the Aurelian Walls in Rome. Our results have shown that the two nanosystems have complementary properties, thus it is possible to tune the antifouling efficiency by combining the two in different proportions.
Thin films of HfO
2 were grown by metal-organic chemical vapour deposition on fused quartz substrates in the temperature range of 400–500 °C using some bis(cyclopentadienyl)bis(alkoxide)hafnium (IV) ...precursors, namely Cp
2Hf(O
i
Pr)
2, Cp
2Hf{OCH(CH
3)CH
2OCH
3}
2, Cp
2Hf{OC(CH
3)
2CH
2OCH
3}
2 and Cp
2Hf{OC(CH
2CH
3)
2CH
2OCH
3}
2. These complexes, analyzed by nuclear magnetic resonance and thermogravimetric measurements, resulted pure and very stable towards air and moisture. The obtained films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy and atomic force microscopy. The deposits contained hafnium and oxygen in the right stoichiometric ratio with a low carbon contamination and they consisted of monoclinic HfO
2 phase (baddeleyite) with a granular surface morphology.
Thin films of HfO2 are grown by metal‐organic (MO)CVD on Si(001) and fused quartz substrates in the temperature range 400–500 °C, using a new series of bis‐cyclopentadienyl bis‐amino‐alkoxide hafnium ...precursors, namely (C5H5)2Hf{OC(CH3)2CH2N(CH3)2}2 and (C5H5)2Hf{OCH(CH3)CH2N(CH3)2}2, stable in air because of their strong coordination to the metal center. The films obtained are investigated by X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS), and atomic force microscopy (AFM). Monoclinic phase HfO2 (baddeleyite) films, characterized by a correct stoichiometric ratio and a granular surface morphology with a roughness/thickness ratio that decreases with increasing deposition rate, are obtained.
Hafnium oxide thin films have been grown by MOCVD on Si(001) and fused quartz substrates in the temperature range 400–500 °C using, as precursors, (C5H5)2Hf{OC(CH3)2CH2N(CH3)2}2 and (C5H5)2Hf{OCH(CH3)CH2N(CH3)2}2, which do not present oligomerization and result highly stable towards air. The films, characterized by XRD, XPS, RBS and AFM analyses, contain the monoclinic HfO2 phase (baddeleyite), a granular surface morphology with a roughness/thickness ratio that decreases with increasing the deposition rate.
Magnesium boride films are synthesized from Mg(BH4)2 by CVD. A new synthesis of the precursor is developed. Deposition time of the samples is varied to study its influence on film composition. The ...films are analyzed by means of X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). The contributions of various chemical species (boride and oxides) in the depth profiles, carried out using Ar ion sputtering combined with cyclic XPS measurements, are separated by peak‐fitting analysis of photoelectron B1s and Auger MgKLL spectra. The samples are composed of MgBx film covered by an overlayer of magnesium and boron oxides.
Magnesium boride films have been synthesized from the single‐source precursor Mg(BH4)2 by chemical vapor deposition. The prepared samples, analyzed by means of XRD and XPS techniques, are found to be composed of MgBx films covered with overlayers of magnesium and boron oxides.
β-diketonate zirconium complexes L
n
ZrCl
4
−
n
(L
=
acetylacetonate, hexafluoroacetylacetonate and 2,2,6,6-tetramethyl-3,5-heptanedionate, with
n
=
2 or 3) have been tested in the polymerization of ...1-hexene using as co-catalyst
N,
N′-dimethylanilinium-tetrakis(pentafluorophenylborate) or ethyltrichloroacetate.
The new β-diketonate complexes (hfac)
2ZrCl
2, (hfac)
3ZrCl, hfac
=
hexafluoroacetylacetonate, and (thd)
2ZrCl
2, thd
=
2,2,6,6-tetramethyl-3,5-heptanedionate, have been prepared in good yield by reacting the corresponding β-diketonate thallium complexes with ZrCl
4 in stoichiometric amounts and they have been characterized by elemental analyses and NMR spectra.
These complexes and the β-diketonate complexes (acac)
2ZrCl
2, (acac)
3ZrCl and (thd)
3ZrCl have been tested as catalysts in the polymerization of 1-hexene in the presence of
N,
N′-(dimethylanilinium)-tetrakis(pentafluorophenylborate) or ethyltrichloroacetate as co-catalysts at room temperature using ethyl aluminum sesquichloride as scavenger.
