Search results for "Note"

USO DI SCAFFOLD BIORIASSORBIBILE PER LA CREAZIONE DI NEOVASI. STUDIO SPERIMENTALE SU MODELLO SUINO

2014

Fast apparent oscillations of fundamental constants

2019

Precision spectroscopy of atoms and molecules allows one to search for and to put stringent limits on the variation of fundamental constants. These experiments are typically interpreted in terms of variations of the fine structure constant $\alpha$ and the electron to proton mass ratio $\mu=m_e/m_p$. Atomic spectroscopy is usually less sensitive to other fundamental constants, unless the hyperfine structure of atomic levels is studied. However, the number of possible dimensionless constants increases when we allow for fast variations of the constants, where "fast" is determined by the time scale of the response of the studied species or experimental apparatus used. In this case, the relevan…

On the behavior of a three-dimensional fractional viscoelastic constitutive model

2016

In this paper a three-dimensional isotropic fractional viscoelastic model is examined. It is shown that if different time scales for the volumetric and deviatoric components are assumed, the Poisson ratio is time varying function; in particular viscoelastic Poisson ratio may be obtained both increasing and decreasing with time. Moreover, it is shown that, from a theoretical point of view, one-dimensional fractional constitutive laws for normal stress and strain components are not correct to fit uniaxial experimental test, unless the time scale of deviatoric and volumetric are equal. Finally, the model is proved to satisfy correspondence principles also for the viscoelastic Poisson’s ratio a…

Accuracy of four digital scanners according to scanning strategy in complete-arch impressions.

2018

STATEMENT OF PROBLEM:Although there are specific and general digital scanning guidelines depending on the system used, it is important to have the necessary flexibility in the acquisition of three-dimensional (3D) images to adapt to any clinical situation without affecting accuracy. PURPOSE:The purpose of this in vitro study was to identify and compare the scanning strategy with the greatest accuracy, in terms of trueness and precision, of four intraoral scanners in the impression of a complete dental arch. MATERIAL AND METHODS:Four digital scanners were evaluated with a 3D measuring software, using a highly accurate reference model obtained from an industrial scanner as a comparator. Four …

Selective Actuation and Tomographic Imaging of Swarming Magnetite Nanoparticles

2021

International audience; Micro- and nanomotors have seen substantial progress in recent years for biomedical applications. However, three grand challenges remain: (i) high velocities to overcome the blood flow, (ii) spatially selective control to enable complex navigation, and (iii) integration of a medical, tomographic real-time imaging method to acquire feedback information. Here, we report the combination of active magnetic matter and a medical imaging technique, namely magnetic particle imaging (MPI), which addresses these needs. We synthesize ∼200 nm magnetic nanoparticles and observe a macroscopic, collective effect in a homogeneous magnetic field with a rotating field vector. The nano…

Enhanced photocatalytic performance of novel electrospun BN/TiO 2 composite nanofibers

2017

International audience; High activity boron nitride/titanium dioxide (BN/TiO2) composite nanofiber photocatalysts were synthesized for the first time via the electrospinning technique. The as-spun nanofibers with a controlled ratio of boron nitride nanosheets (BN) were calcined under air at 500 °C for 4 hours. Their morphological, structural and optical properties were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), BET surface area, Fourier-transform infrared (FTIR), Raman spectroscopy, UV-Visible spectrophotometry and room temperature photoluminescence (PL). The effect of loading different BN sheet amounts on the photocat…

XRMA analysis and X-ray diffraction analysis of dental enamel from human permanent teeth exposed to hydrogen peroxide of varying pH

2019

Background This in vitroinvestigation shows how 3.3% H2O2, at different pH-values affects the enamel. Material and Methods A number of fifteen human premolars were used. The enamel of the coronal half in six of the teeth, were exposed by H2O2. Nine teeth were prepared to enamel powder. The enamel was exposed to 3.3% H2O2, at six different pH-values (pH range 4.5 - 7.0). Analyses of the topography of enamel performed by scanning electron microscope (SEM) and the chemical composition of enamel by X-ray microanalysis (XRMA). X-ray powder diffraction (XRD) analysed the crystallinity in enamel powder. Results The exposure to H2O2 at pH5.5 resulted in a decrease of O in the exposed enamel, and ch…

Mapping electron-beam-injected trapped charge with scattering scanning near-field optical microscopy.

2016

Scattering scanning near-field optical microscopy (s-SNOM) has been demonstrated as a valuable tool for mapping the optical and optoelectronic properties of materials with nanoscale resolution. Here we report experimental evidence that trapped electric charges injected by an electron beam at the surface of dielectric samples affect the sample-dipole interaction, which has direct impact on the s-SNOM image content. Nanoscale mapping of the surface trapped charge holds significant potential for the precise tailoring of the electrostatic properties of dielectric and semiconductive samples, such as hydroxyapatite, which has particular importance with respect to biomedical applications. The meth…

<title>Scanning probe microscopy of nanocrystalline iridium oxide thin films</title>

2003

Structural investigations of nanocrystalline iridium oxide thin films, prepared by dc magnetron sputtering technique were performed by scanning probe microscopy (SPM). SPM studies, using both atomic force microscopy (AFM) and scanning tunnelling microscopy (STM), indicate that the thin films are composed of grains with a size of about 20-50 nm. Fine crystallinity and small RMS microroughness of the films, being well below 2 nm, make iridium oxide thin films promising candidates for nanolithographic applications. The possibility to perform nanolithograhpic processes at a scale of less than 150 nm was successfully examined in AFM and STM modes.© (2003) COPYRIGHT SPIE--The International Societ…

Field-induced tip–sample oxygen transfer in scanning tunneling microscopy on TiO2(110) (1 1).

2008

International audience; A study on the field-induced tip–surface oxygen transfer at room temperature and its influence on the tunneling conditions for stable STM imaging of the TiO2(110) (1 1) surface is reported. A simple model of field-induced transfer is applied to tungsten and platinum–iridium tips. The oxygen transition rates from the sample to the tip or from the tip to the sample depend on the oxygen desorption barriers formed at tunneling distance. For stable imaging the applied bias voltage has to balance the oxygen transfer probabilities in both directions. In the case of Pt/Ir tips, the tunneling conditions for images with clear evidence of bridging oxygen point defects have been…