Search results for "IRRADIATION"
showing 10 items of 1012 documents
In vivo and in vitro effects of an Er:YAG laser, a GaAlAs diode laser, and scaling and root planing on periodontally diseased root surfaces: A compar…
2003
Background and Objectives The aim of the present histologic study was to compare the in vivo and in vitro effects of an erbium: yttrium, aluminum, and garnet (Er:YAG) laser (ERL), combined with a fluorescent calculus detection system, a diode laser (DL) and scaling and root planing (SRP) on periodontally diseased root surfaces. Study Design/Materials and Methods Twenty-four single rooted teeth, considered for extraction due to severe periodontal destruction, were included in the study. Prior to extraction all mesial root surfaces were randomly assigned to the following treatment groups: (1) ERL combined with a calculus detection system with fluorescence induced by 655 nm InGaAsP DL radiatio…
Influence of low power CW laser irradiation on skin hemoglobin changes
2012
Influence of low power laser irradiance on healthy skin using diffuse reflectance spectroscopy and multispectral imaging was studied. Changes of diffuse reflectance spectra in spectral range from 500 to 600 nm were observed after 405 nm, 473 nm and 532 nm laser provocation, leading to conclusion that the content of skin hemoglobin has changed. Peaks in spectral absorbance (optical density) curves corresponded to well-known oxy-hemoglobin absorbance peaks at 542 and 577 nm.
Novel GTA-PVA Fricke gels for three-dimensional dose mapping in radiotherapy
2017
Abstract One of the most recent and promising developments in radiotherapy dosimetry was the introduction of 3D radiation-sensitive gels. These gels present tissue equivalent composition and density, so they also serve as phantoms, and their response is largely independent of radiation quality and dose rate. Some gels are infused with ferrous sulfate and rely on the radiation-induced oxidation of ferrous ions to ferric ions (Fricke-gels). These formulations suffer from spontaneous-oxidation and diffusion of ferric ions after irradiation; chelating agents such as xylenol-orange significantly reduces the latter. Other gel types consist of dispersed monomers, and rely on radiation-induced cros…
Doped TiO2 Nanomaterials and Applications
2008
This special issue brieflyreviews some trends and factors that have impacted heterogeneous photocatalysis with next generation TiO2 nanophotocatalysts that could absorband make use of both UV (290–400 nm) and visible (400–700 nm) sunlight to enhance process efficiencies, along with some issues of current debate in the fundamental understanding of the science that underpins the field. Preparative methods and some characteristics features of doped TiO2 as well as its environmental applications are presented and described. The next generation of doped TiO2 photocatalysts should enhance overall process photoefficiencies in many cases, since doped TiO2s absorb a greater quantity of solar radiati…
Effects of Ionising Radiation on Optical Properties of Lithium Niobate Single Crystals
2005
Studies of thermal and γ-irradiation effects on the optical properties in congruent lithium niobate single crystals containing Mg and Gd dopants including samples with double dopants Y, Mg are reported. Formation of defects at irradiation and thermal treatment of the samples is explored by analysis of the behaviour of electron absorption spectra. Considerable increase of absorption with the dose of γ-radiation is observed at 500 nm. The changes of absorption examined under different conditions are explained by creation and destruction of Nb 4+ defects.
Effect of oxygen deficiency on the radiation sensitivity of sol-gel Ge-doped amorphous SiO2
2008
We report experimental investigation by electron paramagnetic resonance (EPR) measurements of room temperature γ-ray irradiation effects in sol-gel Ge doped amorphous SiO2. We used materials with Ge content from 10 up to 104 part per million (ppm) mol obtained with different preparations. These latter gave rise to samples characterized by different extents of oxygen deficiency, estimated from the absorption band at ~5.15 eV of the Ge oxygen deficient centers (GeODC(II)). The irradiation at doses up to ~400 kGy induces the E'-Ge, Ge(1) and Ge(2) paramagnetic centers around g ~ 2 with concentrations depending on Ge and on GeODC(II) content. We found correlation between Ge(2) and GeODC(II) con…
Irradiation temperature effects on the induced point defects in Ge-doped optical fibers
2017
We present an experimental investigation on the combined effects of temperature and irradiation on Ge-doped optical fibers. Our samples were X-ray (10 keV) irradiated up to 5 kGy with a dose rate of 50 Gy(SiO2)/s changing the irradiation temperature in the range 233-573 K. After irradiation we performed electron paramagnetic resonance (EPR) and confocal microscopy luminescence (CML) measurements. The recorded data prove the generation of different Ge related paramagnetic point defects and of a red emission, different from that of the Ge/Si Non-Bridging Oxygen Hole center. Furthermore, by comparing the behaviour of the EPR signal of the Ge(1) as a function of the irradiation temperature with…
Influence of the simultaneous calibration of multiple ring dosimeters on the individual absorbed dose
2021
Abstract Ring dosimeters for personal dosimetry are calibrated in accredited laboratories following ISO 4037-3 guidelines. The simultaneous irradiation of multiple dosimeters would save time, but has to be carefully studied, since the scattering conditions could change and influence the absorbed dose in nearby dosimeters. Monte Carlo simulations using PENELOPE-2014 were performed to explore the need to increase the uncertainty of H p 0 .07 in the simultaneous irradiation of three and five DXT-RAD 707H-2 (Thermo Scientific) ring dosimeters with beam qualities: N-30, N-80 and N-300. Results show that the absorbed dose in each dosimeter is compatible with each of the others and with the refere…
PbS Nanodots For Ultraviolet Radiation Dosimetry
2011
Lead sulfide (PbS) nanodots in Zirconia (ZrO2) thin film matrix (ZrO2:PbS films) were investigated for UV radiation dosimetry purposes. Samples were fabricated using sol-gel technique. ZrO2:PbS films were irradiated with UV light with wavelengths 250 – 400 nm during 50 minutes. Photoelectron emission spectra of ZrO2:PbS films were recorded and band structure for nonradiated and UV irradiated samples was calculated. It was found that quantity of localized states decreased after UV irradiation while density of localized states was dependent on concentration of PbS nanodots. The observed changes in band structure of ZrO2:PbS films after UV irradiation suggest that the films may be considered a…
Application of the ESR spectrometry to evaluate the original dose in irradiated dried fruit
2008
The identification of irradiated dried fruit can be achieved by means of the electron spin resonance (ESR) spectrometry, as recommended by the European Community, since ionizing radiation induces free radicals in cellulose, a constituent of the shell. The aim of this work was to use the ESR spectrometry also as a quantitative procedure to evaluate the original dose in irradiated dried fruits, using the additive dose method. Little shell pieces, taken from nuts, chestnuts, peanuts and pistachios, were irradiated at original dose values in the range 1 to 8 kGy, and the ESR signal intensity was measured. Each specimen was then reirradiated with added doses of 1 kGy, and the ESR signal was me…