Study of nanoparticles based on Cr and Sb doped TiO2 as pigments for inkjet technology applications

Nanoparticles of the ceramic pigment with composition Ti0.97Cr0.015Sb0.015O2 were prepared by microemulsion-mediated solvothermal method at 180 ºC. Anatase or rutile single phase was obtained depending on the synthesis conditions. Scanning electron microscope analysis showed the formation of nanospheres with particle size around 600 nm. The anatase to rutile transformation temperature was determined by Raman spectroscopy. The evolution of the colour was studied, and it was related with the polymorphic transition. Yellow nanopigments were obtained at low temperature and huge orange colour was observed at high temperature. Nanopigments prepared at 180 ºC were tested with an industrial frit. Similar chromatic coordinates of an industrial orange ceramic pigment obtained at high temperatures were observed. -potential values of the nanoparticles were -57 mV. The size, shape, colour and electrostatic stability of these nanoparticles make them potential candidates to be applied in glazes or inkjet printers as orange ceramic pigments.We thank the “Universitat Jaume I”-project No. P1 1B2013-65 (MJ, MD, HB, EC) for financial suppor

Evidence for the formation of metallic In after laser irradiation of InP

Structural and electronic changes induced by laser irradiation are currently of interest owing to the possibility to tune the mechanical, optical, and transport properties of the irradiated materials. In this work, we investigate the effects of laser irradiation on indium phosphide, InP, by modifying the electronic temperature, Te, of the system within the density functional theory framework and performing molecular dynamics simulations to prove that the laser irradiation also provokes a local thermalization effect. We found that the process can be described by a two-stage mechanism. First, at low Te values (0–1.0 eV), the laser energy induces electronic transitions, while the InP lattice remains undisturbed and cool. In the second stage (with Te in the range of 1.0–4.0 eV), both electron-electron scattering and electron-phonon coupling processes are triggered, increasing the energy of the lattice so as to provoke a Coulomb explosion, which changes some physical chemical properties of InP. The close agreement between the simulations helps explain the formation of metallic In as it is observed in the transmission electron microscopy images

Proof-of-Concept Studies Directed toward the Formation of Metallic Ag Nanostructures from Ag3PO4 Induced by Electron Beam and Femtosecond Laser

In this work, for the first time, the instantaneous nucleation and growth processes of Ag nanoparticles on Ag3PO4 mediated by femtosecond laser pulses are reported and analyzed. The investigated samples are pure Ag3PO4sample, electron-irradiated Ag3PO4 sample, and laser-irradiated sample. Complete characterization of the samples is performed using X-ray diffraction (XRD), Rietveld refinements, field emission scanning electron microscopy, and energy dispersive spectroscopy (EDS). XRD confirms that the irradiated surface layer remains crystalline, and according to EDS analysis, the surface particles are composed primarily of Ag nanoparticles. This method not only offers a one-step route to synthesize Ag nanoparticles using laser-assisted irradiation with particle size control, but also reports a complex process involving the formation and subsequent growth of Ag nanoparticles through an unexpected additive-free in situ fabrication process

Connecting morphology and photoluminescence emissions in β-Ag2MoO4 microcrystals

This work elucidates the morphology-photoluminescence (PL) emission relationships, based on experimental and calculated results, on β-Ag2MoO4 samples synthesized by microwave-assisted hydrothermal method. It was shown that the solvent (water and ammonia) and temperature (120, 130, 140, and 150 °C) play a crucial role in the morphology and PL emissions. A crystal structure model, composed by the local coordination of both Ag and Mo atoms at bulk and exposed surfaces, was built, and the possible mechanism along the synthesis progress was proposed and analyzed. This study provides an idea for the preparation and development of β-Ag2MoO4 based materials with desirable properties

The first 62 AGNs observed with SDSS-IV MaNGA : I. Their characterization and definition of a control sample

We report the characterization of the first 62 Mapping Nearby Galaxies at the Apache Point Observatory active galactic nuclei (AGNs) hosts and the definition of a control sample of non-active galaxies. This control sample was selected in order to match the AGN hosts in terms of stellar mass, redshift, visual morphology and inclination. The stellar masses are in the range 9.4 < log M/M < 11.5, and most objects have redshifts ≤0.08. The AGN sample is mostly comprised low-luminosity AGN, with only 17 ‘strong AGN’ with L([O III]λ5007 Å) ≥ 3.8 × 1040 erg s−1. The inner 1–3 kpc of the control sample galaxies are dominated by the oldest (≥ 4Gyr) component, with a small contribution of intermediate age and young stars (<940 Myr). Examining the relationship between the stellar population properties and L([O III]), we find that with increasing L([O III]), the AGN exhibit a decreasing contribution from the oldest stellar population relative to control galaxies and an increasing contribution from the younger components (∼40 Myr).We also find a correlation of the mean age differences (AGN–control) with L([O III]), in the sense that more luminous AGNs are younger than the control objects, while the low-luminosity AGNs are older. These results support a connection between the growth of the galaxy bulge via formation of new stars and the growth of the Supermassive Black Hole via accretion in the AGN phase

Aspectos anatomopatológicos das neoplasias malignas renais: Anatomopathological aspects of malignant renal neoplasms

As neoplasias renais correspondem ao crescimento exacerbado de células tumorais no interior dos rins, classificadas como benignas ou malignas. Neste estudo será abordado sobre as neoplasias malignas renais, a qual correspondem a maior prevalência e são representadas pelo carcinoma de células renais e o tumor de Wilms, com a finalidade de descrever a respeito dos aspectos anatomopatológicos, disseminando informações para o diagnóstico e manejo precoce. O carcinoma de células renais é mais prevalente no sexo masculino, indivíduos mais velhos, geralmente assintomático, contribuindo para o diagnóstico tardio junto a existência de metástases e terapêutica irresponsiva. Não se trata de uma doença genética, sendo o caráter esporádico o predominante, neste contexto os fatores de risco, sobretudo o tabagismo em seguida de obesidade hemodiálise e doenças genéticas são potenciais desencadeantes da enfermidade. Os exames complementares associado a clínica, junto ao acompanhamento eleva a possibilidade de identificação antes de avanços metastáticos. O tumor de Wilms é típico de crianças, acometendo um ou ambos os rins, normalmente com alguma anomalia genética, sendo os sinais inespecíficos, mas sempre manifestando massa palpável e dor abdominal, a qual os métodos de imagem confirmam o diagnóstico e estimam o prognóstico deste. Neste contexto, elucida-se a transcendência que os aspectos anatomopatológicos das neoplasias malignas renais oferecem para a diagnose precoce, devido a escassez e inespecificidafe das manifestações clínicas. Logo, a junção do perfil de cada neoplasia abordado conduz ao manejo adequado e reduz a incidência de tratamentos agressivos e irresponsivos

Estudo, caracterização e propriedades de ortofosfatos multifuncionais

Scientific research focused on non-toxic inorganic materials with photoluminescence (PL) properties has been intensified in pursuance of biomedical applications. This thesis aims to contribute with the study of the optical properties of pure and Eu3+-doped hydroxyapatite [HA, Ca10(PO4)6(OH)2] and their correlation to its structural, compositional and morphological properties. Moreover, a preliminary study comprising of biocompatibility evaluation, internalization capability and cell labelling by PL is presented. The HA samples were synthesized by chemical precipitation at 90 ºC in a basic (pH ~10) and acidic (pH ~ 5) environment. The addition rate of the precursors was varied for each group (600, 7 ou 1,5 mL/min). Furthermore, the effects of posterior heat treatments in the range of 200-800 ºC on the properties of pure HA, and at 600 ºC and 1100 ºC with normal cooling step, as well as followed by a quenching procedure at liquid N2 for HAEu were also evaluated.La investigación científica en materiales inorgánicos atóxicos con propiedades fotoluminiscentes (FL) tiene sido intensificada para aplicaciones biomédicas. Esta tesis doctoral tiene como objetivo el estudio de las propiedades ópticas de la hidroxiapatita [HA, Ca10(PO4)6(OH)2] y sus correlaciones con las propiedades estructurales, composicionales y morfológicas. Además, se presenta un estudio preliminar con la evaluación de biocompatibilidad, capacidad de internalización y marcación celular por la FL. Las muestras de HA fueron sintetizadas por precipitación química a 90 ºC en un medio básico (pH ~10) y ácido (pH ~5). La velocidad de adición de los precursores fue variada en cada grupo (600, 7 o 1,5 mL/min). Se estudiaran los efectos de los posteriores tratamientos térmicos en temperaturas de 200-800 ºC en las propiedades de la HA pura, y a 600 ºC y 1100 ºC con una etapa de enfriamiento normal, bien como al efectuar enfriamiento rápido en N2 líquido para las muestras HAEu

A novel approach to obtain highly intense self-activated photoluminescence emissions in hydroxyapatite nanoparticles

Defect-related photoluminescence (PL) in materials have attracted interest for applications including near ultraviolet (NUV) excitable light-emitting diodes and in biomedical field. In this paper, hydroxyapatite [Ca10(PO4)6(OH)2] nanorods with intense PL bands (bluish- and yellowish-white emissions) were obtained when excited under NUV radiation at room temperature. These nanoparticles were synthesized via chemical precipitation at 90 °C followed by distinct heat treatments temperatures (200–800 °C). Intense and broad emission profiles were achieved at 350 °C (380–750 nm) and 400 °C (380–800 nm). UV–Vis spectroscopy revealed band gap energies (5.58–5.78 eV) higher than the excitation energies (~3.54 and ~2.98 eV at 350 and 415 nm, respectively), confirming the contribution of defect energy levels within the forbidden zone for PL emissions. The structural features were characterized by X-ray diffraction, Rietveld refinement, thermogravimetric analysis, and Fourier transform infrared spectroscopy. By means of these techniques, the relation between structural order-disorder induced by defects, chemical reactions at both lattice and surface of the materials as well as the PL, without activator centers, was discussed in details.The authors are grateful to the FAPESP (#2013/11144-3), FAPESP/CEPID (#2013/07296-2), CNPq (#573636/2008-7), CAPES/PNPD (#20131475), Universitat Jaume I (P1 1B2013-65), and Ministerio de Economia y Competitividad (Salvador Madariaga program, PRX155/00261) for the financial support. Special thanks to Mr. R. Camargo for FE-SEM and TEM images

Structural properties and self-activated photoluminescence emissions in hydroxyapatite with distinct particle shapes

The understanding on defect-related photoluminescence (PL) properties of hydroxyapatite (HA) particles has a fundamental importance in the technological field for the development of new non-toxic biomedical and optical devices. However, the mechanisms responsible for this intrinsic PL in HA are not completely elucidated in the literature yet. In the present paper, stoichiometric and calcium-deficient HA nano- and micro-particles were synthesized by chemical precipitation. The influence of structural and morphological features on the intrinsic PL and electronic structure of this material were investigated by varying the addition rate of the phosphate precursor (0.15, 7.00 or 600.00 mL/min) and pH (4.5–5.0 or 9.5–10.0) value adopted in the precipitation. The results indicated that the structural order at long- and short-range varied with the synthesis conditions and particle shapes (rods, needles, plates, and rices). The blue and green PL emissions were attributed to defects (bulk, surface and interface) in the samples. These defects promoted the formation of additional energy levels within the band gap, as revealed by using two distinct excitation wavelengths for photoemission measurements. The energies of these wavelengths (~ 3.54 and ~ 2.98 eV at 350 and 415 nm, respectively) were lower than the band gap energies of HA samples (from 5.59 to 5.72 eV). A general model was proposed to explain the occurrence of self-activated PL in HA structure

In Situ Growth of Bi Nanoparticles on NaBiO3, delta-, and beta-Bi2O3 Surfaces: Electron Irradiation and Theoretical Insights

Herein, we present a combined experimental and theoretical study of the in situ growth of Bi nanoparticles on NaBiO3, δ-, and β-Bi2O3 surfaces mediated by the electron beam of a high-resolution transmission electron microscope. Density functional theory and quantum theory of atoms in molecule calculations were used to gain a deeper insight into the experimental observations and to provide an atomistic basis for understanding the formation mechanism of Bi NPs on NaBiO3, δ-, and β-Bi2O3 under electron beam irradiation. Analysis of the experimental data and electron density distributions suggests that the formation of Bi NPs can be related to the structural and electronic changes occurring within the octahedral [BiO6] clusters, and to a lesser extent, [NaO6] clusters, which serve as the constituent building blocks of NaBiO3. Our findings indicate that as a function of the number of added electrons, the formation of β-Bi2O3 takes place first followed by the subsequent appearance of metallic Bi NPs generated in the crystal by electron beam irradiation