To verify the influence of the functional elements particular size for the radiation attenuation coefficients and mechanical properties radiation shielding material based on epoxy resin,we prepare two WO_(3)/E44 samples with different particular sizes of WO_(3) by a solidified forming approach.The linear attenuation coefficients of these samples are measured forγ-ray photo energies of 59.6,121.8,and 344.1 keV,etc.using narrow beam transmission geometry.It is found that the linear attenuation coefficients would increase with the decreasing particle size of the WO_(3) in the epoxy resin based radiation shielding material.The theoretical values of the linear attenuation coefficients and mass attenuation are calculated using WinXcom,and good agreements between the experimental data and the theoretical values are observed.From the studies of the obtained results,it is reported that from the shielding point of view the nano-WO_(3) is more effective than micro-WO_(3) in the epoxy resin based radiation shielding material.
The localized surface plasmon resonance of gold nanoparticles enables them to be excellent light scattering sensing reagents and efficient lignt-heat convertors for potential diagnostics and therapeutics.In this work,gold nanoparticles of 15 nm in size were synthesized and conjugated with a kind of arginine-glycine-aspartic acid peptide(RGD)to target the cancer cells.Under a conventional dark field microscope,the scattering images from normal and cancer cells are very different.Only a few of gold nanoparticles bind to the membrane of normal cells due to nonspecific interaction.Yet for cancer cells,the concentration of gold nanoparticles inside cancer cells is much higher than that inside normal cells,showing a strong light scattering signal.By exposing these cells to an external laser irradiation,cancer cells were selectively destructed because of the heat conversion of gold nanoparticles inside them,but normal cells still kept alive due to the absence of gold nanoparticles in them.These results incidated that gold nanoparticles might be potential contrast reagents for targeted cancer imaging and laser therapy.
This study was carried out to look for the substitute products of lead cerrobend block and determine whether the products can give more radiation dose to the tumor in the skin and superficial tumors in radiotherapy treatment. Five kinds of PbO/ Er203/Epoxy（E-51） samples used as the cerrobend block in the electron beam radiotherapy treatment were prepared success- fully by a solidified forming approach. The central axis depth dose and off-axis dose profiles in the water phantom were calcu- lated using BEAMnrc/DOSEXYZnrc user codes. The results revealed that there were more energy deposition events induced by low energy electron beams in the surface of the water phantom. These electron beams were attributed to Compton scattering and photoemission between photons and erbium, plumbum elements. The maximum dose （Dm） and the depth at the maximum dose （Rm） were linearly dependent on the mass fraction of erbium and plumbum element in the sample. The max dose and its depth varied depending on the combined actions of new electrons and transmission electrons.
