Search results for "RADIATION"

Polymerization reactions and modifications of polymers by ionizing radiation

2020

International audience; Ionizing radiation has become the most effective way to modify natural and synthetic polymers through crosslinking, degradation, and graft polymerization. This review will include an in-depth analysis of radiation chemistry mechanisms and the kinetics of the radiation-induced C-centered free radical, anion, and cation polymerization, and grafting. It also presents sections on radiation modifications of synthetic and natural polymers. For decades, low linear energy transfer (LLET) ionizing radiation, such as gamma rays, X-rays, and up to 10 MeV electron beams, has been the primary tool to produce many products through polymerization reactions. Photons and electrons in…

Thermal aggregation of bovine serum albumin at different pH: comparison with human serum albumin.

2007

We report here a study on thermal aggregation of BSA at two different pH values selected to be close to the isoelectric point (pI) of this protein. Our aim is to better understand the several steps and mechanisms accompanying the aggregation process. For this purpose we have performed kinetics of integrated intensity emission of intrinsic and extrinsic dyes, tryptophans and ANS respectively, kinetics of Rayleigh scattering and of turbidity. The results confirm the important role played by conformational changes in the tertiary structure, especially in the exposure of internal hydrophobic regions that promote intermolecular interactions. We also confirm that the absence of electrostatic repu…

Cosmic ray composition and energy spectrum from 1–30 PeV using the 40-string configuration of IceTop and IceCube

2012

Astroparticle physics 42, 15 - 32 (2013). doi:10.1016/j.astropartphys.2012.11.003

Kodolspektroskopijas un beta radiometrijas rezultāti vides monitoringā Salaspils kodolreaktora apkārtnē (1966.g. līdz 1995.g.)

1998

The 4th international comparison on EPR dosimetry with tooth enamel: Part 1: Report on the results

2011

This paper presents the results of the 4th International Comparison of in vitro electron paramagnetic resonance dosimetry with tooth enamel, where the performance parameters of tooth enamel dosimetry methods were compared among sixteen laboratories from all over the world. The participating laboratories were asked to determine a calibration curve with a set of tooth enamel powder samples provided by the organizers. Nine molar teeth extracted following medical indication from German donors and collected between 1997 and 2007 were prepared and irradiated at the Helmholtz Zentrum München. Five out of six samples were irradiated at 0.1, 0.2, 0.5, 1.0 and 1.5 Gy air kerma; and one unirradiated s…

Ionic liquids and microwave irradiation as synergistic combination for polar Diels–Alder reactions using properly substituted heterocycles as dienoph…

2012

For the DA reactions between nitropyrrole derivatives and isoprene, the combination of microwave irradiation and protic ionic liquid, has a notable synergistic effect. DFT calculations suggest that a supplementary energy ranking in the IR region of 1700-1400 cm-1 can favour the structural changes in the reactants to reach the TS. Fil: Mancini, Pedro Maximo Emilio. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Departamento de Química; Argentina Fil: Ormachea, Carla. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa F…

La1-xSrxCo1-yFeyO3-delta perovskites: Preparation, characterization and solar photocatalytic activity

2015

Abstract LaCoO3 perovskites substituted by Sr at the A site and/or by Fe at the B site have been prepared by the citrate method. Characterizations by several techniques, such as specific surface area (BET method), XRD, TPR, SEM, UV–vis in DRS mode, XPS and TGA analyses, have been performed. The so prepared La1−xSrxCo1−yFeyO3−δ perovskites are semiconductor materials showing band gap energy values from 1.9 to 3.2 eV. They displayed solar photocatalytic activity for the 2-propanol degradation in gas–solid regime. The photocatalytic results suggest that the perovskites containing Fe are less active and the activity decreases by increasing the Fe content, however the presence of iron avoids the…

Photocatalytic Degradation of 4-Nitrophenol in Aqueous Suspension by Using Polycrystalline TiO2 Impregnated with Lanthanide Double-Decker Phthalocyan…

2007

The photocatalytic activity of polycrystalline TiO2 samples impregnated with rare-earth-metal diphthalocyanines was investigated. The 4-nitrophenol (4-NP) photocatalytic degradation in aqueous suspension was used as a probe reaction. Commercial anatase TiO2 was impregnated with home-prepared double-decker phthalocyanine complexes of the lanthanide metals, such as Ce, Pr, Nd, Sm, Ho, and Gd. In particular, the impregnation with Ho, Sm, and Nd complexes, acting as sensitizers, proved beneficial for the photoactivity of the studied systems. Significant improvements of the TiO2-based catalytic system appeared possible in terms of lower impregnation loading, enhanced photoreactivity under solar …

X-ray powder diffraction data for five lanthanoid chromates [Ln2(CrO4)3(H2O)5]·2H2O (Ln=La,Pr,Nd,Sm,Eu)

1994

X-ray powder diffraction data are reported for a series of isomorphous compounds of [Ln2(CrO4)3(H2O)5]·2H2O, where Ln=La, Pr, Nd, Sm, or Eu. The compounds crystallize in monoclinic space group P21/c (No: 14) with Z=4. Refined unit cell parameters and indexed powder diffraction patterns are given.

Elemental composition of sediments from a former silver mine in Freiberg/East Germany

1999

Abstract We have determined the contents of 48 elements in 11 representative sediments from a former Ag-mine in Freiberg/Sachsen. As analytical method the instrumental neutron activation analysis (INAA) was used without chemical preconcentration. Strongly varying compositions were observed for both the main and trace elements. Of particular interest were the high lanthanide and Th/U contents in these sediments.