194 research outputs found
Magnetic properties of epsilon iron(III) oxide nanorod arrays functionalized with gold and copper(II) oxide
A sequential chemical vapor deposition (CVD) - radio frequency (RF)-sputtering approach was adopted to fabricate supported nanocomposites based on the scarcely investigated \u3b5-iron(III) oxide polymorph. In particular, \u3b5-Fe2O3 nanorod arrays were obtained by CVD, and their subsequent functionalization with Au and CuO nanoparticles (NPs) was carried out by RF-sputtering under mild operational conditions. Apart from a multi-technique characterization of material structure, morphology and chemical composition, particular efforts were dedicated to the investigation of their magnetic properties. The pertaining experimental data, discussed in relation to the system chemico-physical characteristics, are directly dependent on the actual chemical composition, as well as on the spatial distribution of Au and CuO nanoparticles. The approach adopted herein can be further implemented to control and tailor different morphologies and phase compositions of iron oxide-based nanomaterials, meeting thus the open requests of a variety of technological utilizations
XPS analysis of Fe2O3-TiO2-Au nanocomposites prepared by a plasma-assisted route
Fe2O3 nanodeposits have been grown on fluorine-doped tin oxide (FTO) substrates by plasma
enhanced-chemical vapor deposition (PE-CVD). Subsequently, the obtained systems have been
functionalized through the sequential introduction of TiO2 and Au nanoparticles (NPs) by means of
radio frequency (RF)-sputtering. The target nanocomposites have been specifically optimized in
view of their ultimate functional application in solar-driven H2 generation. In the present study, our
attention is focused on a detailed X-ray photoelectron spectroscopy (XPS) characterization of the
surface composition for a representative Fe2O3-TiO2-Au specimen. In particular, this report
provides a detailed discussion of the analyzed C 1s, O 1s, Fe 2p, Ti 2p, and Au 4f regions. The
obtained results point to the formation of pure Fe2O3-TiO2-Au composites, with gold present only
in its metallic state and each of the constituents maintaining its chemical identity
A study of Pt-/alpha-Fe2O3 nanocomposites by XPS
alpha-Fe2O3 matrices were deposited on Fluorine-doped Tin Oxide (FTO) substrates by Plasma Enhanced-
Chemical Vapor Deposition (PE-CVD) from Fe(hfa)_2TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA =
N,N,Nâ,Nâ-tetramethylethylenediamine). The obtained nanosystems were subsequently functionalized by platinum nanoparticles (NPs) via Radio Frequency (RF)-sputtering, exposing samples either to a pre- or post-sputtering thermal treatment at 650°C for one hour in air. Interestingly, Pt oxidation state in the final composite systems strongly depended on the adopted processing conditions. In this work, a detailed X-ray Photoelectron Spectroscopy (XPS) analysis was carried out in order to investigate the material chemical composition, with particular regard to the relative Pt(0)/Pt(II)/Pt(IV) content. The obtained results evidenced that, when annealing is performed prior to sputtering, only PtO and PtO2 are revealed in the final Pt/alpha-Fe2O3 nanocomposite. In a different way, annealing after sputtering results in the co-presence of Pt(0), Pt(II) and Pt(IV) species, the former arising from the thermal decomposition of PtO2 to metallic platinum
WO3-decorated ZnO nanostructures for light-activated applications
In the present work, a two-step vapor-phase route was implemented for the tailored design of ZnO\u2013WO3
nanoheterostructures supported on fluorine-doped tin oxide (FTO) substrates. Under optimized conditions,
the sequential use of chemical vapor deposition (CVD) and radio frequency (RF)-sputtering for the deposition
of zinc and tungsten oxides respectively, resulted in the growth of calyx-like ZnO nanostructures uniformly
decorated by a conformal dispersion of low-sized WO3 nanoparticles. The target materials were
characterized by means of a multi-technique approach, with particular regard to their structural, compositional, morphological and optical properties. Finally, their photocatalytic performances were preliminarily tested in the abatement of NOX gases (NO and NO2). Due to the unique porous morphology of the ZnO nanodeposit and the high density of ZnO\u2013WO3 heterojunctions, WO3-decorated ZnO revealed appealing De-NOX characteristics in terms of both degradation efficiency and selectivity. Such features, along with the photoinduced superhydrophilicity and self-cleaning properties of the present nanomaterials, candidate them as promising functional platforms for applications in smart windows and building materials for environmental remediation
Soft Loans as an Instrument of Development Finance: A Comparative Assessment and Options for the Future
Within the framework of the Post-2015 Development Agenda, discussions on Financing for Development and the future of Official Development Assistance (ODA) have intensified. Amongst the instruments under review are soft loans. Though originally conceived as export promotion tools, development objectives have recently become more prominent in soft loan policies. Albeit regulated through the Arrangement on Officially Supported Export Credits, soft loans claim a place amongst the instruments of development policy. By means of comparative case study analysis, this paper examines the relevance of soft loans as an instrument of development policy. We discuss three characteristics of soft loan financing: (i) the institutional heterogeneity of programmes between countries, (ii) the hybrid nature of the instruments between export promotion and development objectives, and (iii) the underlying notions of development. Upon that basis, scenarios for the future use of soft loans as an instrument of development finance are presented
Manganese(II) Molecular Sources for Plasma-Assisted CVD of Mn Oxides and Fluorides: From Precursors to Growth Process
A viable route to manganese-based materials of high technological interest is plasma-assisted chemical vapor deposition (PA-CVD), offering various degrees of freedom for the growth of high-purity nanostructures from suitable precursors. In this regard, fluorinated \u3b2-diketonate diamine Mn(II) complexes of general formula Mn(dik)2\ub7TMEDA [TMEDA = N,N,N\u2032,N\u2032-tetramethylethylenediamine; Hdik = 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (Hhfa), or 1,1,1-trifluoro-2,4-pentanedione (Htfa)] represent a valuable option in the quest of candidate molecular sources for PA-CVD environments. In this work, we investigate and highlight the chemico-physical properties of these compounds of importance for their use in PA-CVD processes, through the use of a comprehensive experimental\u2013theoretical investigation. Preliminary PA-CVD validation shows the possibility of varying the Mn oxidation state, as well as the system chemical composition from MnF2 to MnO2, by simple modulations of the reaction atmosphere, paving the way to a successful utilization of the target compounds in the growth of manganese-containing nanomaterials for different technological applications
Surface Functionalization of Grown-on-Tip ZnO Nanopyramids: From Fabrication to Light-Triggered Applications
We report on a combined
chemical vapor deposition (CVD)/radio frequency
(RF) sputtering synthetic strategy for the controlled surface modification
of ZnO nanostructures by Ti-containing species. Specifically, the
proposed approach consists in the CVD of grown-on-tip ZnO nanopyramids,
followed by titanium RF sputtering under mild conditions. The results
obtained by a thorough characterization demonstrate the successful
ZnO surface functionalization with dispersed Ti-containing species
in low amounts. This phenomenon, in turn, yields a remarkable enhancement
of photoactivated superhydrophilic behavior, self-cleaning ability,
and photocatalytic performances in comparison to bare ZnO. The reasons
accounting for such an improvement are unravelled by a multitechnique
analysis, elucidating the interplay between material chemico-physical
properties and the corresponding functional behavior. Overall, the
proposed strategy stands as an amenable tool for the mastering of
semiconductor-based functional nanoarchitectures through <i>ad
hoc</i> engineering of the system surface
Supported MnâOâ nanosystems for hydrogen production through ethanol photoreforming
Photoreforming promoted by metal oxide nanophotocatalysts is an attractive route for clean and sustainable hydrogen generation. In the present work, we propose for the first time the use of supported MnO nanosystems, both pure and functionalized with Au nanoparticles (NPs), for hydrogen generation by photoreforming. The target oxide systems, prepared by chemical vapor deposition (CVD) and decorated with gold NPs by radio frequency (RF) sputtering, were subjected to a thorough chemico-physical characterization and utilized for a proof-of-concept Hâ generation in aqueous ethanolic solutions under simulated solar illumination. Pure MnO nanosystems yielded a constant hydrogen production rate of 10 mmol hâ»Âč mâ»ÂČ even for irradiation times up to 20 h. The introduction of Au NPs yielded a significant enhancement in photocatalytic activity, which decreased as a function of irradiation time. The main phenomena causing the Au-containing photocatalyst deactivation have been investigated by morphological and compositional analysis, providing important insights for the design of MnâOâ-based photocatalysts with improved performances
Validation of the T-Lymphocyte Subset Index (TLSI) as a Score to Predict Mortality in Unvaccinated Hospitalized COVID-19 Patients
Lymphopenia has been consistently reported as associated with severe coronavirus disease
2019 (COVID-19). Several studies have described a profound decline in all T-cell subtypes in hospitalized patients with severe and critical COVID-19. The aim of this study was to assess the role of
T-lymphocyte subset absolute counts measured at ward admission in predicting 30-day mortality in
COVID-19 hospitalized patients, validating a new prognostic score, the T-Lymphocyte Subset Index
(TLSI, range 0â2), based on the number of T-cell subset (CD4+ and CD8+) absolute counts that are below prespecified cutoffs. These cutoff values derive from a previously published work of our research
group at Policlinico Tor Vergata, Rome, Italy: CD3+CD4+ < 369 cells/”L, CD3+CD8+ < 194 cells/”L.
In the present single-center retrospective study, T-cell subsets were assessed on admission to the
infectious diseases ward. Statistical analysis was performed using JASP (Version 0.16.2. JASP Team,
2022, The Amsterdam, The Netherlands) and Prism8 (version 8.2.1. GraphPad Software, San Diego,
CA, USA). Clinical and laboratory parameters of 296 adult patients hospitalized because of COVID-19
were analyzed. The overall mortality rate was 22.3% (66/296). Survivors (S) had a statistically
significant lower TLSI score compared to non-survivors (NS) (p < 0.001). Patients with increasing
TLSI scores had proportionally higher rates of 30-day mortality (p < 0.0001). In the multivariable
logistic analysis, the TLSI was an independent predictor of in-hospital 30-day mortality (OR: 1.893,
p = 0.003). Survival analysis showed that patients with a TLSI > 0 had an increased risk of death
compared to patients with a TLSI = 0 (hazard ratio: 2.83, p < 0.0001). The TLSI was confirmed as an
early and independent predictor of COVID-19 in-hospital 30-day mortalit
Increase of Vascular Endothelial Growth Factor and Decrease of MCP-1 and Some Updated Epidemiology Aspects of Cystic Echinococcosis Human Cases in Calabria Region
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