Valentina Caratto

NIR Persistent Luminescence of Lanthanide Ion-Doped Rare-Earth Oxycarbonates: The Effect of Dopants

A series of luminescent rare-earth ion-doped hexagonal II-type Gd oxycarbonate phosphors Gd2-xRExO2CO3 (RE = Eu(3+), Yb(3+), Dy(3+)) have been successfully synthesized by thermal decomposition of the corresponding mixed oxalates. The Yb(3+) doped Gd-oxycarbonate has evidenced a high persistent luminescence in the NIR region, that is independent from the temperature and makes this materials particular attractive as optical probes for bioimaging.

Influence of TiO2 Nanoparticles on Growth and Phenolic Compounds Production in Photosynthetic Microorganisms

The influence of titanium dioxide nanoparticles (pure anatase and 15% N doped anatase) on the growth of Chlorella vulgaris, Haematococcus pluvialis, and Arthrospira platensis was investigated. Results showed that pure anatase can lead to a significant growth inhibition of C. vulgaris and A. platensis (17.0 and 74.1%, resp.), while for H. pluvialis the nanoparticles do not cause a significant inhibition. Since in these stress conditions photosynthetic microorganisms can produce antioxidant compounds in order to prevent cell damages, we evaluated the polyphenols content either inside the cells or released in the medium. Although results did not show a significant difference in C. vulgaris, the phenolic concentrations of two other microorganisms were statistically affected by the presence of titanium dioxide. In particular, 15% N doped anatase resulted in a higher production of extracellular antioxidant compounds, reaching the concentration of 65.2 and 68.0 mg gDB −1 for H. pluvialis and A. platensis, respectively.

Enhancement of TiO2 NPs activity by Fe3O4 nano-seeds for removal of organic pollutants in water

The enhancement of the photocatalytic activity of TiO2 nanoparticles (NPs), synthesized in the presence of a very small amount of magnetite (Fe3O4) nanoparticles, is here presented and discussed. From X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses, the crystallinity of TiO2 nanoparticles (NPs) seems to be affected by Fe3O4, acting as nano-seeds to improve the tetragonal TiO2 anatase structure with respect to the amorphous one. Photocatalytic activity data, i.e., the degradation of methylene blue and the Ofloxacin fluoroquinolone emerging pollutant, give evidence that the increased crystalline structure of the NPs, even if correlated to a reduced surface to mass ratio (with respect to commercial TiO2 NPs), enhances the performance of this type of catalyst. The achievement of a relatively well-defined crystal structure at low temperatures (Tmax = 150 °C), preventing the sintering of the TiO2 NPs and, thus, preserving the high density of active sites, seems to be the keystone to understand the obtained results.

Effects of Nebulizer Position, Gas Flow, and CPAP on Aerosol Bronchodilator Delivery: An In Vitro Study

BACKGROUND: The aim of this study was to investigate the effects of different delivery circuit configurations, nebulizer positions, CPAP levels, and gas flow on the amount of aerosol bronchodilator delivered during simulated spontaneous breathing in an in vitro model. METHODS: A pneumatic lung simulator was connected to 5 different circuits for aerosol delivery, 2 delivering CPAP through a high-flow generator tested at 30, 60, and 90 L/min supplementary flow and 5, 10, and 15 cm H2O CPAP and 3 with no CPAP: a T-piece configuration with one extremity closed with a cap, a T-piece configuration without cap and nebulizer positioned proximally, and a T-piece configuration without cap and nebulizer positioned distally. Albuterol was collected with a filter, and the percentage amount delivered was measured by infrared spectrophotometry. RESULTS: Configurations with continuous high-flow CPAP delivered higher percentage amounts of albuterol compared with the configurations without CPAP (9.1 ± 6.0% vs 6.2 ± 2.8%, P = .03). Among configurations without CPAP, the best performance was obtained with a T-piece with one extremity closed with a cap. In CPAP configurations, the highest delivery (13.8 ± 4.4%) was obtained with the nebulizer placed proximal to the lung simulator, independent of flow. CPAP at 15 cm H2O resulted in the highest albuterol delivery (P = .02). CONCLUSIONS: Based on our in vitro study, without CPAP, a T-piece with a cap at one extremity maximizes albuterol delivery. During high-flow CPAP, the nebulizer should always be placed proximal to the patient, after the T-piece, using the highest CPAP clinically indicated.

Structural studies on copper and nitrogen doped nanosized anatase

Abstract Pure TiO2, N- and Cu-doped and double-doped (Cu, N) samples were synthesized via sol–gel route in order to investigate the local and average structure of the crystalline TiO2 synthesized under different pH conditions. Samples are mainly constituted of anatase phase, even though low but significant amounts of secondary brookite grew in most samples. A detailed structural characterization was performed by means of synchrotron X-ray elastic scattering experiments; structural data of the different samples were obtained by means of the Rietveld refinement, whereas insights about their local structure were gained by means of the pair distribution analysis.

Antibacterial activity of standard and N-doped titanium dioxide-coated endotracheal tubes: an in vitro study

Objective The aim of this study was to assess the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa of two nanoparticle endotracheal tube coatings with visible light-induced photocatalysis. Methods Two types of titanium dioxide nanoparticles were tested: standard anatase (TiO2) and N-doped TiO2 (N-TiO2). Nanoparticles were placed on the internal surface of a segment of commercial endotracheal tubes, which were loaded on a cellulose acetate filter; control endotracheal tubes were left without a nanoparticle coating. A bacterial inoculum of 150 colony forming units was placed in the endotracheal tubes and then exposed to a fluorescent light source (3700 lux, 300-700 nm wavelength) for 5, 10, 20, 40, 60 and 80 minutes. Colony forming units were counted after 24 hours of incubation at 37°C. Bacterial inactivation was calculated as the percentage reduction of bacterial growth compared to endotracheal tubes not exposed to light. Results In the absence of light, no relevant antibacterial activity was shown against neither strain. For P. aeruginosa, both coatings had a higher bacterial inactivation than controls at any time point (p < 0.001), and no difference was observed between TiO2 and N-TiO2. For S. aureus, inactivation was higher than for controls starting at 5 minutes for N-TiO2 (p = 0.018) and 10 minutes for TiO2 (p = 0.014); inactivation with N-TiO2 was higher than that with TiO2 at 20 minutes (p < 0.001), 40 minutes (p < 0.001) and 60 minutes (p < 0.001). Conclusions Nanosized commercial and N-doped TiO2 inhibit bacterial growth under visible fluorescent light. N-TiO2 has higher antibacterial activity against S. aureus compared to TiO2.

Sorbents Coupled to Solar Light TiO2-Based Photocatalysts for Olive Mill Wastewater Treatment

The aim of this work was to couple physical-chemical approaches with photocatalysis to reduce by a simple, inexpensive way the organic load of olive mill wastewater (OMW), mandatorily prior to the final discharge. Before irradiation, different sorbents were tested to remove part of the organic fraction, monitored by measuring chemical oxygen demand (COD) and polyphenols (PP). Different low-cost, safe materials were tested, that is, Y zeolite (ZY), montmorillonite, and sepiolite. Considerable decrease of organic load was obtained, with the highest abatement (40%) provided by ZY (10 g L−1 in 1 : 10 OMW). Use of the three sorbents, in particular ZY, was convenient compared to commercial activated carbons. UV light photocatalytic tests, performed using P25 TiO2 on ZY-treated OMW, yielded quantitative remediation (ca. 90%). Also solar light provided significative results, PP being lowered by 74% and COD by 56%. Sol-gel anatase TiO2 and N-doped anatase TiO2 were also tested, obtaining good results, around 80% PP and 40% COD. Finally, an integrated approach was experimented by ZY-supported anatase TiO2 (TiO2@ZY). This photoreactive sorbent allowed one-pot treatment of OMW significative abatements of PP (77%) and COD (39%) with only 1 g L−1 material, under solar light.

Porous polydimethylsiloxane membranes loaded with low-temperature crystallized TiO 2 NPs for detachable antibacterial films

TiO2 was prepared via sol–gel synthesis, and in order to obtain crystallized anatase in a colloidal suspension, it was subjected to a hydrothermal process in the presence of a minimum amount of nanoparticles, which acted as nucleation seeds. Concurrently, high-pH sol–gel syntheses were performed with the increase in NH3 solutions as a comparison for the samples’ activity. Polydimethylsiloxane was chosen as supporting material for the TiO2 nanoparticles for its high surface area and its stability against catalyst’s photoactivity. They were both processed with the electrospinning technique: It was possible to disperse titania among PDMS fibers and to obtain detachable polymeric membranes with the appearance of white soft sheets. These membranes show antibacterial activity under fluorescent light, and thus, they may be used as a film for several kinds of surfaces. The synthesized samples were controlled and characterized by means of rheological measurements, scanning electron microscopy images together with EDS maps, differential scanning calorimetry analyses, diffuse reflectance spectra for energy gap (Egap) calculations and recycling photocatalytic experiments, while Escherichia Coli inactivation gave evidence of the antibacterial activity.