The current work demonstrates the first reported successful synthesis of unique alpha-TeO2 hybrid microstructures through thermal oxidation of Te microtubes in a horizontal tube furnace at different temperatures in the range 220-470 degrees C, under oxygen flow. The obtained microstructures were carefully characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy. They exhibited characteristic morphologies with porous scaffold microtubes covered along their whole length with pearl-like microwires. The possible formation mechanism of the obtained microstructures was also discussed.

GaS single crystal layers have been thermally treated under argon flow for 4 h at two different temperatures (700 degrees C and 900 degrees C). The starting GaS sample and the annealed ones have been characterized by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy. It was found that GaS transformed into beta-Ga2S3 through the formation of Ga2S3 intermediate phase. Moreover, such an oxidation process involved the growth of dense Ga2S3 sub-micron crystallites at a temperature of 700 degrees C and relatively long beta-Ga2S3 nanowires (up to 4 mu m) at a temperature of 900 degrees C. Experiments also evidenced that an intentional supply of oxygen was unfavourable both to the formation of Ga2S3 phase and to the growth of sub-micron crystallites and nanowires.

In this paper, we report the obtention of In2O3 nanostructured microwires by the decomposition thermal treatment of InSe single crystal in two-steps under an oxygen-ammonia flow without the presence of any catalyst. Long In2O3 microwires with uniform shape and homogeneous surface were first synthesized through thermal treatment of InSe single crystal at temperature of about 640 degrees C; then, furnace temperature was increased to 750 degrees C and, as annealing time proceeded, the obtained microwires served as substrates on which nanorod branches grew. The shape and the structure of the microarchitectures were characterized by means scanning electron microscopy, transmission electron microscopy, selected area diffraction pattern, X-Ray diffraction and Raman spectroscopy. Our results indicated that In2O3 primary wires with a clean surface grew in the [100] direction and that the secondary protuberances grew in the [011] direction. A possible growth mechanism of the hierarchical microwires was also proposed. (C) 2012 Elsevier B.V. All rights reserved.

In this work the results of the thermal oxidation of GaSe thin films in air at different temperatures are presented. The structural and morphological characteristics of the thermally annealed products were studied by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). The as-deposited GaSe films were amorphous and they transformed into polycrystalline GaSe films with a hexagonal crystal structure at a temperature around 400°C. Thermal oxidation at 650°C resulted in the formation of mixed Ga2Se3 and Ga2O3compounds both in the monoclinic phase. At higher temperatures, Ga2Se 3 disappeared and complete oxidation of the initial compound occurred. The optical energy gaps of products were determined at room temperature by transmittance measurements using UV-vis-NIR spectroscopy.

Abstract Selective benzaldehyde reduction to benzyl alcohol was accomplished using a new catalyst based on Pd dispersed on mayenite (Ca12Al14O33) support. In this work, mayenite has been doped in its nanocages with H- ions to investigate its role in the reduction of aldehydes. Benzaldehyde reduction was observed in H2 atmosphere (120°C, 8 atm). Catalytic performances compared to commercial Pd/C catalyst are superior in terms of selectivity and comparable as activity.

In this work, the inorganic chemical profiles of soil samples collected at different sites in the Salentum peninsula (Italy, Apulia region) are discussed. The samples were re-suspended in the laboratory, for PM10 sampling, using a ventilated wooden chamber and were then chemically analysed measuring the abundances of 17 elements. Different land use categories of soils (olive grove, arable land, vineyards, sand, and urban dust) were included in the 50 samples analysed: 45 collected in background areas and five collected in the urban area of Lecce. The objectives were to compare the chemical profiles of raw soil and re-suspended PM10 for different crustal sources and to estimate the potential improvements in the calculation of the enrichment factors of atmospheric PM10. The variability of elemental abundances in samples of the same category of soil collected in different zones was of the same order of magnitude as the differences observed between the various categories of soil. This allows the calculation of a weighted average composition of soil and urban dust and the corresponding weighted average composition of re-suspended PM10. In re-suspended PM10 from average background soil, all of the elements except Ca, Na, K and V have larger abundances with respect to raw soil. In urban dust, this is limited to Ca, V and Mg. The crustal enrichment factors (EFs) of atmospheric PM10 were evaluated.

Mass concentrations of PM2.5, mineral dust, organic carbon (OC) and elemental carbon (EC), water-soluble organic carbon (WSOC), sea salts and anthropogenic metals have been studied in a city-port of south Italy (Brindisi). This city is characterized by different emission sources (ship, vehicular traffic, biomass burning and industrial emissions) and it is an important port and industrial site of the Adriatic sea. Based on diagnostic ratios of carbonaceous species we assess the presence of biomass burning emissions (BBE), fossil fuel emissions (FFE) and ship emission (SE). Our proposed conversion factors from OC to OM are higher than those reported in the literature for urban site: the reason of this could be due to the existence of aged combustion aerosols during the sampling campaign (WSOC/OC = 0.6 ± 0.3).

The analysis reported in thiswork has been performed to characterise PM10concentrationmeasured in an urban background site in Lecce (Apulia region, Italy). PM10 concentration and its inorganic chemical composition have been studied using three procedures: a qualitative analysis of the correlation coefficients between the different species and of the crustal enrichment factor; the cluster analysis (CA) and the principal component analysis (PCA). The results of the three procedures are in good agreement. The five groups identified by the CA correspond to the five principal components obtained with the PCA and they reflect the results qualitatively inferred using the two-species correlation coefficients. The CA results helped in putting in evidence a correlation between Ni, V and sulphate that was less evident in the PCA. The relative abundance of V is larger with wind fromtheNNWdirectionswhere themain industrial sites of the region are located. This suggests the presence of anthropogenic inorganic secondary aerosol generated by a common source of V and SO2 that are likely the industrial releases and the ship emissions. The absolute PCA (APCA) allowed the quantitative apportionment of the five components observed: crustal matter (49.5%), secondary inorganic aerosol (24.1%), marine aerosol (6.3%), traffic (16.5%), and industrial (2.1%). Observed PM10 concentration clearly shows a seasonal pattern, opposite to the one observed in the northern and central Italy, with average PM10 larger in the warm season (spring and summer) with respect to the cold season as a consequence of the increase of crustal matter contribution likely due to the intrusion of African dust. These intrusions are more frequent in the warm season and have an influence on daily PM10 concentrations variable between 6% and 120% in this site. Correlation with meteorological data indicates that the more intense cases of intrusions of African dust happen with wind blowing from the SW direction. Average PM10 concentration decreases of about 23% during precipitation. The decrease ismainly due to the decrease in crustal matter contribution and secondary inorganic aerosol. The sum of the other three sources is almost not changing during precipitation.

In2O3 microrods were grown by thermal oxidation of InSe single crystal under a mixture of argon−oxygen flow without the presence of a catalyst. Microrods were obtained at the temperature of about 640 °C after a thermal treatment of 180 min. The morphology, structure, and composition of the prepared materials were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction spectroscopy (XRD). The microrods had a hexagonal cross-section with a diameter range of 1−3 μm and a length of between 20 and 30 μm. Structural analysis showed that the microstructures were cubic In2O3 crystal with a lattice constant of a = 10.115 Å. The possible mechanism of the formation of In2O3 microstructures is also discussed in this work

Integrating nephelometer measurements have been combined with co-located in space and time PM10 and PM1 mass concentration measurements to highlight the benefits of integrating aerosol optical properties with the chemical speciation of PM1 and PM10 samples. Inorganic ions (SO4 2−, NO3 −, NH4 +, Cl−, Na+, K+, Mg2+, and Ca2+), metals (Fe, Al, Zn, Ti, Cu, V, Mn, and Cr), and the elemental and organic carbon (EC and OC, respectively) have been monitored to characterize the chemical composition of PM1 and PM10 samples, respectively. The scattering coefficient (σp) at 450 nm, the scattering Ångström coefficient (Å) calculated at the 450–635 nm wavelength pair, and the scattering Ångström coefficient difference (ΔÅ) retrieved from nephelometer measurements have been used to characterize the optical properties of the particles at the surface. The frequency distribution of the Å daily means during the one-year monitoring campaign, performed at a southeastern Italian site, has allowed identifying three main Å variability ranges: Å≤0.8, 0.8 < Å≤1.2, and Å > 1.2. We found that σp and ΔÅ mean values and the mean chemical composition of the PM1 and PM10 samples varied with the Å variability range. σp and ΔÅ reached the highest (149Mm−1) and the smallest (0.16) mean value, respectively, on the days characterized by Å > 1.2. EC, SO4 2−, and NH4 + mean mass percentages also reached the highest mean value on the Å > 1.2 days, representing on average 8.4, 9.8, and 4.2%, respectively, of the sampled PM10 mass and 12.4, 10.6, and 7.7%, respectively, of the PM1 mass. Conversely, σp and ΔÅ mean values were equal to 85Mm−1 and 0.55, respectively, on the days characterized by Å≤0.8 and the EC, SO4 2−, and NH4 + mean mass percentages reached smaller values on the Å≤0.8 days, representing 4.5, 6.0, and 1.9% of the PM10 mass and 9.4, 7.3, and 5.8% of the PM1 mass, respectively. Primary and secondary OC (POC and SOC, respectively) contributions also varied with the Å variability range. POC and SOC mean mass percentages reached the highest and the smallest value, respectively, on the days characterized by Å > 1.2. Conversely, POC and SOC mean mass percentages reached the smallest and the highest value, respectively, on the days characterized by Å≤0.8. It has also been shown that the PM, OC, OC+EC, POC, and SOC mass scattering cross sections varied significantly with the Å variability range, because of the Å dependence on aerosol sources and/or emission, transport, and transformation mechanisms. Therefore, it has been shown that Å daily mean values can represent a good tool to better differentiate the chemical speciation of size-fractioned PM samples.

Abstract Angström exponents (Å) and dust concentrations from the Barcelona Supercomputing Center-Dust REgional Atmospheric Model (BSC-DREAM) were used to infer the impact of long-range transported desert dust particles at the ground level and evaluate their role on the chemical composition of PM1 and PM10 samples. Å values were calculated from the scattering coefficients at 450 and 635 nm, retrieved from integrating nephelometer measurements. Nephelometer measurements were performed at a coastal site (Lecce, 40.33° N, 18.11° E) of south-eastern Italy from December 2011 till November 2012. Days characterized by Å daily mean values smaller than 0.95 and modelled daily dust concentrations larger than 0.1 μg m−3 at 86 m above the ground level were considered representative of days affected by African dust particles up to the ground level (dusty days). Both criteria have allowed identifying 86 dusty days during the investigated period. The analysis of 24-h simultaneously collected PM10 and PM1 samples revealed that the PM1 mass concentrations increased linearly with PM10 both in dusty and dustfree days, which were identified as the ones characterized by Å daily mean values larger than 1.3 and PM1/PM10 ratios larger than 0.35. These results suggested that the PM1 samples were also affected by desert particles on dusty days. In fact, chemical analyses revealed that the Al and Fe mean mass concentrations were larger in dusty day PM1 and PM10 samples. Then, we found that the crustal matter contribution was nearly twice and more than twice larger in dusty PM1 and PM10 samples, respectively, than in corresponding dust-free samples. Mass contributions of organic and elemental carbon, sulfates, and ammonium even if smaller in dusty samples than in dust-free PM1 and PM10 samples revealed the significant role of the anthropogenic pollution also on dusty days.

Background: Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were applied on PM10 particle data in order to: identify particle clusters that can be differentiated on the bases of their chemical composition and morphology, investigate the relationship among the chemical and morphological parameters and evaluate differences among the sampling sites. PM10 was collected in 3 different sites in central Italy characterized by different conditions: yard, urban and rural sites. The concentration of 20 chemical parameters (C, O, Na, Mg, Al, Si, P, Cd, Cl, K, Ca, Sn, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn) were determined by Scanning Electron Microscopy - Energy Dispersive X-ray Spectroscopy (SEM-EDS) and the particle images were processed by an image analysis software in order to measure: Area, Aspect Ratio, Roundness, Fractal Dimension, Box Width, Box Height and Perimeter. Result: Results revealed the presence of different clusters of particles, differentiated on the bases of chemical composition and morphological parameters (aluminosilicates, calcium particles, biological particles, soot, cenosphere, sodium chloride, sulphates, metallic particles, iron spherical particles). Aluminosilicates and Calcium particles of rural and urban sites showed a similar nature due to a mainly natural origin, while those of the yard site showed a more heterogeneous composition mainly related to human activity. Biological particles and soot can be differentiated on the bases of the higher loads of Fractal Dimension, which characterizes soot, and content of Na, Mg, Ca, Cl and K which characterize the biological ones. The soot of the urban site showed higher loadings of Roundness and Fractal Dimension than the soot belonging to the yard and rural sites, this was due to the different life time of the particles. The metal particles, characterized mainly by the higher loading of iron, were present in two morphological forms: spherical and angular particles. The first were generated by a fusion process at high temperature, while the second one had crustal origin (those characterized by typical terrigenous elements) and also human origin. Conclusion: In this work a protocol for the morphological-chemical characterization of single particles has been developed. SEM analysis allows to classify particles in 10 different families and PCA and HCA have provided information about the sources of PM and similarities and differences among the sites.

Harbours are important for economic and social development of coastal areas but they also represent an anthropogenic source of emissions often located near urban centres and industrial areas. This increases the difficulties in distinguishing the harbour contribution with respect to other sources. The aim of this work is the characterisation of main sources of PM2.5 acting on the Brindisi harbour-industrial area, trying to pinpoint the contribution of in-port ship emissions to primary and secondary PM2.5.

Indium monoselenide (InSe) nanowires were grown by the thermal evaporation method in argon atmosphere without the presence of any catalysts using InSe polycrystalline powder as the source material. No nanostructure growth was observed at deposition temperatures below 580 °C. The nanostructures were discernable at temperatures above 620 °C. Pure InSe nanowires were obtained at the deposition temperature of 660 °C for 50 min. The diameters of the nanowires were from 50 to 240 nm and their lengths were up to several micrometers. X-ray diffraction spectrum reveals that the synthesized products were single-crystalline of the β-phase hexagonal structure of InSe with lattice constants a = 4.006 Å and c = 16.642 Å. The strong peak due to the reflection from the (004) crystal plane reveals that most nanowires grow with a strong preferred orientation

Abstract Surface chemical composition of particles has a key role in determining the reactivity and optical properties of atmospheric aerosol. This composition depend on the particles sources and formation processes and it influences human health and climate. In this work, the X-ray photoelectron spectroscopy (XPS) has been used for the systematic surface characterization of atmospheric particles of different sizes, collected using a 10-stage MOUDI-II rotating cascade impactor in an urban background site. The high resolution XPS spectra allowed to distinguish different organic functional groups (C-C/CC, -C-O, -CO/-C(O)N, -C(O)O, C-O3=) and to speciate the detectable hetero-elements, sulphur (S-O42-, sulphone and sulphide compounds), nitrogen (N-H4+, N-O3-, N-O2- and organic-nitrogen compounds), sodium (Na+) and chlorine (Cl-) species. Significant differences in particles belonging to accumulation (small particles) and coarse (large particles) modes were observed being due to the formation processes and sources from which particles originated. The oxygen concentrations is inversely correlated with carbon concentrations, however, the content of oxidized organic carbon is not correlated with oxygen content confirming that the oxygen increment observed in large particles can likely be attributed to the contribution of inorganic species (crustal origin). The speciation of nitrogen showed ammonium only in the accumulation mode and nitrate only in coarse mode excluding the presence of ammonium nitrate of secondary origin in the area studied. A correlation of Na and Cl was attributed to the marine contribution with an excess of Cl on the surface correlated with the depletion of Cl observed in the bulk of particles. © 2015 Elsevier Ltd.