The radiation-induced displacement damage in yttrium borate (YBO3) is studied under X-ray, proton, and alpha irradiation. The photoluminescence (PL) was tested before and after irradiation to determine whether damage ...
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The radiation-induced displacement damage in yttrium borate (YBO3) is studied under X-ray, proton, and alpha irradiation. The photoluminescence (PL) was tested before and after irradiation to determine whether damage occurred and whether it could be queried by examining the PL spectrum. Two different dopants (cerium and europium) were used to activate the phosphor because each provides not only a different spectral signature but also a different mechanism for altering the spectrum between the pre- and post-PL measurements. X-rays, being primarily ionizing radiation, did not show any significant change between the pre and post measurements. We expected protons and alphas to damage the crystal structure, evidence of which could be seen in the change in the spectra before and after irradiation. However, we found no change under alpha exposure (3.6 × 1010 particles/cm2) and a significant change after proton exposure (5 × 1015 particles/cm2). While the material appears to be sensitive to protons, we cannot rule out its sensitivity to alphas because the alpha fluence may be too low to show an effect. This result provides strong indication that our materials are being damaged by particle radiation and that the radiation effects can be quantified.
Stable dispersions of nanoscale Kevlar fibers with diameters between 3 and 30 nm were obtained by deprotonating macroscale, commercial Kevlar yarns with potassium hydroxide in dimethyl sulfoxide. Those aramid nanofibe...
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ISBN:
(纸本)9788888785332
Stable dispersions of nanoscale Kevlar fibers with diameters between 3 and 30 nm were obtained by deprotonating macroscale, commercial Kevlar yarns with potassium hydroxide in dimethyl sulfoxide. Those aramid nanofibers were surface-treated with phosphoric acid (PA) and glutaraldehyde (GA), and assembled via layer-by-layer (LBL) and vacuum-assisted filtration method into transversely isotropic films. Through Fourier-transform infrared spectroscopy, transmission-electron microscopy, uniaxial tensile testing and thermo-gravimetric analysis, it was shown that PA hydrolyzes aramid nanofibers which created useful functional groups for surface bonding and GA polymerizes those PA-hydrolyzed nanofibers which served as an inter-fiber crosslinker to improve network properties. A hierarchically structured film made of alternating layers of the high-stiffness, PA/GA-treated, aramid-nanofiber network and high-ductility polyurethane/poly (acrylic acid) was demonstrated to have stiffness and strength exceeding those of commercial Kevlar fiber-woven mats.
Landfill (TPA) Sukawinatan Palembang is an open dumping system which covers an area of 25 hectares. This system may bring an environmental damage to the surrounding area because it does not provide leachate treatment....
Landfill (TPA) Sukawinatan Palembang is an open dumping system which covers an area of 25 hectares. This system may bring an environmental damage to the surrounding area because it does not provide leachate treatment. Leachate is the landfill waste that dissolves many compounds that contain pollutants from both organic substances and heavy metal origin. This paper presents the results of laboratory analysis on samples of leachate as well as shallow groundwater from the surrounding area. The results were compared to established quality standards to evaluate whether the leachate has influenced the quality of the shallow groundwater in the surrounding area. The results show that there are some indications that the quality of groundwater has been polluted by the leachate of both organic substances and heavy metals produced by the Sukawinatan landfill.
The tribological properties and mass loss of polytetrafluoroethylene (PTFE) composites filled with carbon fiber (CF) or potassium titanate whisker (PTW) after the immersion in 30% sulfuric acid solution for 5 or 15 da...
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Polylactide (PLA) nanocomposites containing inorganic nanofillers, either 3 wt.% montmorillonite (MMT) or 5 wt.% nano-sizes calcium carbonate (NCC), and 15 wt.% cellulose fibres were prepared and studied. Good dispers...
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ISBN:
(纸本)9788888785332
Polylactide (PLA) nanocomposites containing inorganic nanofillers, either 3 wt.% montmorillonite (MMT) or 5 wt.% nano-sizes calcium carbonate (NCC), and 15 wt.% cellulose fibres were prepared and studied. Good dispersion of nanoparticles in the PLA matrix was obtained. X-ray analysis and TEM examination evidenced that exfoliation of MMT was achieved. Dynamic mechanical response, thermal and mechanical properties, and also thermal stability of the composite materials were investigated with various methods. All the fillers, especially MMT, enhanced cold crystallization of PLA matrix, possibly by augmenting nucleation.
Dear Editor,We previously demonstrated (liang et al.,2002) that rodent multipotent adult progenitor cells (MAPC) can self-renew longterm while maintaining multilineage differentiation *** MAPC express a number of plur...
Dear Editor,We previously demonstrated (liang et al.,2002) that rodent multipotent adult progenitor cells (MAPC) can self-renew longterm while maintaining multilineage differentiation *** MAPC express a number of pluripotency-related transcription factors (TF) including Oct4 and Rex1 but not Nanog and Sox2,two other TF known to play a significant role in the maintenance of the pluripotency of embryonic stem cells (ESC) (Ulloa-Montoya et al.,2007).
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