Publications by authors named "Marco A Schiavon"

A theoretical-experimental approach is proposed to convert the photoluminescence spectra of colloidal perovskite quantum dot ensembles into accurate estimates for their intrinsic particle size distribution functions. Two main problems were addressed and properly correlated: the size dependence of the first excitonic transition in a single cube-shaped quantum dot and the inhomogeneous broadening of the fluorescence line shape due to the size nonuniformity of the chemically prepared quantum dot suspension in addition to the single-dot homogeneous broadening. By applying the reported methodology to CsPbBr3 quantum dot samples belonging to the strong and intermediate confinement regimes, the calculated size distributions exhibited close agreement with those obtained from transmission electron microscopy, with precise estimates for the average particle size and standard deviation.

View Article and Find Full Text PDF

Chitosan is a promising natural polymer for coatings, it combines intrinsic antibacterial and pro-osteoblastic properties, but the literature still has a gap from the development to behavior of these coatings, so this systematic review aimed to answer, "What is the relationship between the physical and chemical properties of polymeric chitosan coatings on titanium implants on antibacterial activity and osteoblast viability?". PRISMA guidelines was followed, the search was applied into 4 databases and grey literature, without the restriction of time and language. The selection process occurred in 2 blinded steps by the authors.

View Article and Find Full Text PDF

To develop a β-AgVO gel and evaluate its physicochemical stability and antifungal activity against . The gel was prepared from the minimum inhibitory concentration (MIC) of β-AgVO. The physicochemical stability was evaluated by centrifugation, accelerated stability (AS), storage (St), pH, syringability, viscosity and spreadability tests and antifungal activity by the agar diffusion.

View Article and Find Full Text PDF

Perovskite nanocrystals hold significant promise for a wide range of applications, including solar cells, LEDs, photocatalysts, humidity and temperature sensors, memory devices, and low-cost photodetectors. Such technological potential stems from their exceptional quantum efficiency and charge carrier conduction capability. Nevertheless, the underlying mechanisms of photoexcitation, such as phase segregation, annealing, and ionic diffusion, remain insufficiently understood.

View Article and Find Full Text PDF

To evaluate the biological and mechanical properties of an adhesive with nanostructured silver vanadate (AgVO). Specimens in poly(methyl methacrylate) (PMMA) were treated with Ultra Corega Cream (UCCA) denture adhesive with or without AgVO. Biofilms of , and were grown and the viable cells counted.

View Article and Find Full Text PDF

Objectives: To incorporate the nanostructured silver vanadate decorated with silver nanoparticles (AgVO) into denture base materials: heat-cured (HC) and 3D printed (3DP) resins, at concentrations of 2.5 %, 5 %, and 10 %; and to evaluate the antimicrobial activity in two multi-species biofilm: (1) Candida albicans, Candida glabrata, and Streptococcus mutans, (2) Candida albicans, Pseudomonas aeruginosa, and Staphylococcus aureus, and the wettability.

Methods: The AgVO was added to the HC powder, and printed samples were coated with 3DP with AgVO incorporated.

View Article and Find Full Text PDF

Objective: The aim of this study was to evaluate the roughness, hardness, and color change of pit and fissure sealants of two commercial brands (Fluroshield ™ and Ultraseal XT ™) incorporated with nanostructured silver vanadate nanomaterial decorated with silver nanoparticles (β-AgVO) in concentrations (0% - control, 2.5% and 5%).

Material And Methods: Two commercial brands Fluroshield TM and Ultraseal XT ™ were used to make the samples with dimensions of 6 × 6 × 4 mm.

View Article and Find Full Text PDF

Quantum dots (QDs) have attracted much attention and exhibit many attractive properties, including high absorption coefficient, adjustable bandgap, high brightness, long-term stability, and size-dependent emission. It is known that to obtain high-quality luminescent properties (i.e.

View Article and Find Full Text PDF

Purpose: This study incorporated the nanomaterial, nanostructured silver vanadate decorated with silver nanoparticles (AgVO), into heat-cured resin (HT) at concentrations of 2.5%, 5%, and 10% and compared the adhesion of multispecies biofilms, surface characteristics, and mechanical properties with conventional heat-cured (HT 0%) and printed resins.

Materials And Methods: AgVO was incorporated in mass into HT powder.

View Article and Find Full Text PDF

Nanomaterials have been investigated as saturable absorbers for ultrafast lasers because of their large photoinduced transparency related to ground-state bleaching. However, the quantum dot size effect on the photoinduced transparency in the strong confinement regime has not been explored due to the challenge of accurately measuring the ground state and the excited-state absorption cross-sections. At the same time, these optical properties are essential to calculate several chemical and physical quantities at the nanoscale.

View Article and Find Full Text PDF

An experimental-theoretical approach is proposed to investigate the size-dependent photobleaching of colloidal semiconductor quantum dots (QDs) excited by a nanosecond pulsed laser. In the experimental background, the ground-state absorption and photoluminescence (PL) spectra of chemically prepared QDs are monitored over an excitation time at distinct laser irradiances. The magnitude of photobleaching in the QD solution is quantified by the decay rate of the PL signal as a function of the excitation time and the laser power.

View Article and Find Full Text PDF

Lead (Pb) halide perovskite nanocrystals, with the general formula APbX , where A=CH NH , CH(NH ) , or Cs and X=Cl , Br , or I , have emerged as a class of materials with promising properties due to their remarkable optical properties and solar cell performance. However, important issues still need to be addressed to enable practical applications of these materials, such as instability, mass production, and Pb toxicity. Recent studies have carried out the replacement of Pb by various less-toxic cations as Sn, Ge, Sb, and Bi.

View Article and Find Full Text PDF

Purpose: This in vitro study aimed to investigate the effect of incorporating the semiconductor nanostructured silver vanadate decorated with silver nanoparticles (β-AgVO3) in a dual-cure resin cement on the degree of conversion (DC), microhardness, roughness, color, adhesion properties before and after artificial aging, and antimicrobial efficacy.

Material And Methods: Three test groups were established: control (without β-AgVO3), with the incorporation of 2.5% and 5% (by weight) of β-AgVO3 in dual-cure resin cement (Allcem, FGM).

View Article and Find Full Text PDF

The cytotoxic and genotoxic effects of commercial endodontic sealers (AH Plus, Sealer 26 and Endomethasone N) incorporated with nanostructured silver vanadate decorated with silver nanoparticles (AgVO - at concentrations 2.5, 5, and 10%) on human gingival fibroblast (HGF), and the silver (Ag ) and vanadium (V /V ) ions release were evaluated. Cytotoxicity, cell death, and genotoxicity tests were carried out with extract samples of 24-hr and 7-days.

View Article and Find Full Text PDF

A facile hydrothermal method to synthesize water-soluble copper indium sulfide (CIS) nanocrystals (NCs) at 150 °C is presented. The obtained samples exhibited three distinct photoluminescence peaks in the red, green and blue spectral regions, corresponding to three size fractions, which could be separated by means of size-selective precipitation. While the red and green emitting fractions consist of 4.

View Article and Find Full Text PDF

The modification of endodontic sealers with nanoparticles to confer antimicrobial activity allow greater effect, with interaction at a molecular level. The nanostructured silver vanadate decorated with silver nanoparticles (AgVO) is a nanomaterial unprecedented in dentistry for this application. This study incorporated the AgVO into three endodontic sealers of different compositions and evaluate the cytotoxicity and release of compounds.

View Article and Find Full Text PDF

Statement Of Problem: Dental porcelain restorations are subject to biological failures related to secondary caries and periodontal disease leading to prosthesis replacement.

Purpose: The purpose of this in vitro study was to explore the microbiological and mechanical properties of dental porcelain incorporated with different percentages of silver vanadate (β-AgVO) through microbiological analysis, roughness tests, and the Vickers microhardness test.

Material And Methods: IPS InLine porcelain specimens were made by using a cylindrical Teflon matrix in the dimensions of 8×2 mm.

View Article and Find Full Text PDF

Lead halide perovskites have emerged as promising materials for light-emitting devices. Here, we report the preparation of colloidal CsPbBr nanoplatelets (3 × 4 × 23 nm) experiencing a strong quasi-one-dimensional quantum confinement. Ultrafast transient absorption and broadband fluorescence up-conversion spectroscopies were employed to scrutinize the carrier and quasiparticle dynamics and to obtain a full description of the spectroscopic properties of the material.

View Article and Find Full Text PDF

CdTe/CdS core/shell quantum dots (QDs) are formed in aqueous synthesis via the partial decomposition of hydrophilic thiols, used as surface ligands. In this work, we investigate the influence of the chemical nature (functional group and chain length) of the used surface ligands on the shell formation. Four different surface ligands are compared: 3-mercaptopropionic acid, MPA, thioglycolic acid, TGA, sodium 3-mercaptopropanesulfonate, MPS, and sodium 2-mercaptoethanesulfonate, MES.

View Article and Find Full Text PDF

Halide perovskites are revolutionizing the photovoltaic and optoelectronic fields with outstanding performances obtained in a remarkably short time. However, two major challenges remain: the long-term stability and the Pb content, due to its toxicity. Despite the great effort carried out to substitute the Pb by a less hazardous element, lead-free perovskite still remains more unstable than lead-containing perovskites and presents lower performance as well.

View Article and Find Full Text PDF

We report here on the direct observation of distinct two-photon transition channels in glutathione-capped (GSH) CdTe quantum dots (QDs) in a very strong confinement regime. CdTe-GSH QDs with different average diameters (2.5, 3.

View Article and Find Full Text PDF

Objective: This preliminary study aimed to evaluate the antimicrobial activity, flow and radiopacity of endodontic sealers with nanostructured silver vanadate decorated with silver nanoparticles (AgVO3).

Methods: The minimum inhibitory concentration (MIC) of AgVO3 was evaluated against . Specimens were prepared from the following endodontic sealers: AH Plus (DENTSPLY DeTrey GmbH, Konstanz, Germany), Sealapex (Sybron Endo, Orange, CA, USA), Sealer 26 (DENTSPLY, Petrópolis, Brazil) and Endofill (DENTSPLY, Petrópolis, Brazil), with concentrations of 0%, 2.

View Article and Find Full Text PDF

Objective: The purpose of this study was evaluate, for the first time, the impact of incorporation of nanostructured silver vanadate (β-AgVO3) in antibiofilm and mechanical properties of dental acrylic resins (poly(methyl methacrylate), PMMA).

Design: The β-AgVO3 was synthesized and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and microanalysis (SEM/EDS). Resins specimens were prepared with 0-10% wt.

View Article and Find Full Text PDF

This work used L-tartaric acid as a model molecule to evaluate how the use of inert and oxidizing atmospheres during pyrolysis affected the physical and optical properties of the resulting carbon dots (CDs). Pyrolysis revealed to be a simple procedure that afforded CDs in a single step, dismissed the addition of organic solvents, and involved only one extraction stage that employed water. By X-ray diffraction a dependency between the structure of the CDs and the atmosphere (oxidizing or inert) used during the pyrolysis was found.

View Article and Find Full Text PDF

We describe the use of cadmium telluride quantum dots (CdTe QDs) as antennas for the photosensitization of nitric oxide release from a ruthenium nitrosyl complex with visible light excitation. The CdTe QDs were capped with mercaptopropionic acid to make them water-soluble, and the ruthenium nitrosyl complex was cis-[Ru(NO)(4-ampy)(bpy)2](3+) (Ru-NO; bpy is 2,2'-bipyridine, and 4-ampy is 4-aminopyridine). Solutions of these two components demonstrated concentration-dependent quenching of the QD photoluminescence (PL) as well as photoinduced release of NO from Ru-NO when irradiated by 530 nm light.

View Article and Find Full Text PDF