This study was performed on γ-irradiated ethylene-propylene diene terpolymer (EPDM) loaded with lead zirconate titanate. The inorganic phase has a perovskite structure with general formula ...Pb(Zr0.65−xCexTi0.35)O3. The three composites with different Ce dopant concentrations revealed the stabilization activity of filler against oxidation proved by chemiluminescence investigation in respect to pristine polymer. The presence of cerium low concentrations in the solid lead zirconate titanate nanoparticles causes significant slowing of oxidation rate during radiation exposure. The improvement in the stabilization feature of filler is correlated with the existence of traps, whose interaction with free radicals assumes medium energy due to their convenient depth.
•Doped lead zirconate titanate stabilizes efficiently EPDM substrate.•Free radicals interact with radiation defects in solid filler.•The antioxidant activity is proportional with filler concentration.
This paper presents the investigation work on different polymeric materials used as insulation materials of conductors in a multicore instrumentation cable. Among differently colored materials, only ...the white one presented cracks after a few years of use. Isothermal and non-isothermal DSC measurements were performed on initial (non-used) and aged (in service used or laboratory aged) materials as well as on raw materials in order to characterize their stability and the ageing state after storage, use in service or laboratory ageing. As shown by the oxidation induction time values, a pronounced antioxidant loss occurred for all materials during storage or service; plus a strong effect of the ambient light on stability was observed for the white insulation material. Around 3% of filler, consisting mainly of TiO
2 particles (as revealed by SEM-XRF elemental analysis), was found in the white material. The higher degradability of the white material can be related to both the photocatalytic effect of the TiO
2 particles and rapid loss of stabilizers.
Due to the presence of efflorescences and improper microclimate conditions for conservation, pink-pigmented areas were reported in two historic monuments in Northern and Central part of Romania. The ...aims of the present study were to find the nature of pink pigments observed on the pictorial layer, original and infilling mortar, to investigate the presence of carotenoids both on mural paintings and in the isolated halophilic bacterial strains and to preliminary characterize and identify the producing strains. Their role in the aesthetical biodeterioration of historic monuments was also pointed out. Obtained Raman spectra of the pink pigments extracted both from the isolated bacterial cultures (molecularly identified as mostly related to Halobacillus hunanensis and Halobacillus naozhouensis) and from the mural painting samples contain diagnostic bands of carotenoids. These results were confirmed by FTIR spectroscopy. The strong Raman signal of bacterial carotenoids detected on mural painting indicated their potential use as biomarker molecules in the evaluation of contamination and state of conservation of mural paintings and lithic monuments. Our results contribute to opening a new direction in cultural heritage restoration to assess the conservation status on the basis of interdisciplinary research, starting with spectroscopic methods (Raman, FTIR) and confirmed by microbiological analysis.
•Novel β-LiYF4: Ce, Tb crystals have been prepared.•Thresholds of amplified spontaneous emission (ASE) and laser effects have been measured.•Laser emission was characterized.
β-NaYF4 crystals family ...are interesting materials and have potential for various applications.
Here we present our research regarding amplified spontaneous emission (ASE) and laser effects of three materials: LiY0.7 F4: (Ce0.2 Tb0.1), NaY0.5 F4: (Ce0.4 Tb0.1) and LiLuY0.7 F4: (Ce0.2 Tb0.1), prepared by hydrothermal synthesis method. The luminescent active ion is Tb3+.
β- LiY0.7 F4: (Ce0.2 Tb0.1) crystals with a hexagonal plate shape have ASE threshold at 400 mW/cm2, excitation with λex = 365 nm and a laser threshold at 490 J for a doped PMMA rod with a length of 25 mm. Laser line was observed at 542 nm.
We have investigated the optical nanopatterning of trilayer graphene. Multiple 20 nm parallel lines were written by Quantum Optical Lithography. Partial and complete nanoablation have been studied. ...The electrons emission from nanosized area of the resist has produced nanoablation.
The writing method could be applied to prototype nanodevice with different 2D materials.
A series of novel β-NaYF4: Ce,Tb crystals were prepared by hydrothermal synthesis with different Ce doping concentrations. Ce doping modifies the growth process. The mean size of crystals was 230 ...nm-1820 nm with a hexagonal rods shape. With an increase of the Ce doping concentrations, the ratio of H/D (Height/Diameter) is continuously decreased from 4.4 to 2.2. Optical properties are determined by Tb concentration. The maximum PL intensity was observed on 60% Ce doping.
The accelerated ageing by γ-irradiation was accomplished for the evaluation of ethylene-propylene-diene terpolymer (EPDM) as electrical insulation in the cable manufacture. Three complementary ...procedures: FT-IR spectroscopy, isothermal and nonisothermal chemiluminescence and absorption/resorption current measurements were applied on a certain formulation for depicting the main material characteristics foreseen in the applications as cable electrical insulations. The explanation of structural modifications in relation with the magnitude of received energy is presented.
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