Materials Applications
Determination of Mass Attenuation Coefficients of T, U, Np, and Pu for Oxygen Kα X-Rays Using an Electron Microprobe by P Pöml and X Llovet, Microsc Microanal |
https://doi.org/10.1017/S1431927620001282 Electron probe microanalysis
(EPMA) is an analytical
technique widely used for characterization of nuclear materials. However, accurate analysis of nuclear materials containing light elements (for example, C, N, O) is still difficult because of the large uncertainties affecting the mass attenuation coefficients (MACs) of Kα X-rays of light elements in actinide absorbers. In this study, we performed measurements of the MACs of T, U, Np, and Pu for O X-rays using a shielded electron microprobe. Te MACs were obtained by measuring, at varying accelerating voltages, relative X-ray intensities emitted from TO2 PuO2
, UO2 , NpO2 , and targets and processing them with the computer program
XMAC. Our results showed that the MACs implemented in the Monte Carlo simulation program PENELOPE, which are based on the photoionization cross-section calculations of Sabbatucci and Salvat (Rad Phys Chem 121 [2016] 122–40), provide the best agreement with our measurements (Figure). Te PENELOPE MACs consistently yielded accurate EPMA analysis of a uranium- doped americium oxide sample, which also contained Np and Pu.
Biological Applications
Confocal Analysis of Distribution and Persistence of Sindbis Virus (TaV-GFP) Infection in Midguts of Aedes aegypti Mosquitoes by JJ Saredy, FY Chim, ZL Lyski, YP Ahearn, and DF Bowers, Microsc Microanal | doi:10.1017/ S1431927620001270
Biological transmission of arthropod-borne-viruses
(arboviruses) to vertebrate hosts by hematophagous insects poses a global threat because such arboviruses can result in a range of serious public health infectious diseases. Female mosquitoes were fed blood containing a virus reporter, SINV (Tosea asigna Virus [TaV]-GFP) that produces green fluorescent protein (GFP) in infected cells. Te posterior midgut (PMG), an integral organ of transmission, must be breeched before the virus can disseminate to potentially infect the mosquito salivary glands for transmission to vertebrates. Infected PMGs were dissected from viremic blood-fed mosquitoes and labeled with primary antibodies against SINV antigens followed by a secondary antibody conjugated with Texas-red fluorochrome (Figure). Te detection of SINV antigens preceded the accumulation of reporter virus GFP. SINV-TaV-GFP was first observed in the PMG, the primary target tissue, at 3 days post-blood-feeding. Te virus was sequestered in circumscribed foci and replicated in PMG peristaltic muscles (secondary target tissue) following dissemination. GFP was observed to persist in PMGs for 30 days post-infection.
66 doi:10.1017/S1551929520000826
Comparison of tabulated MACs of actinide elements for O Kα X-rays. Solid lines are MAC tabulations from the literature; open circles are the experimental results of the present study. The accu- racy of the measured MACs is estimated to be better than 5%.
Merged image showing overlap of TX-red labeling of SINV antigens on outskirts of virus foci (arrows) and epithelial cells (arrowhead) prior to robust expression and accumulation of GFP. See Figures 5A and 5B in the published paper for single-channel images.
www.microscopy-today.com • 2020 May
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