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Assessment of radiation exposure for materials in the LANSCE Spallation Irradiation Facility
Materials samples were irradiated in the Los Alamos Radiation Effects Facility (LASREF) at the Los Alamos Neutron Science Center (LANSCE) to provide data for the Accelerator Production of Tritium (APT) project on the changes in mechanical and physical properties of materials in a spallation target environment. The targets were configured to expose samples to a variety of radiation environments including high-energy protons, mixed protons and neutrons, and predominantly neutrons. The irradiation was driven by an 800 MeV 1 mA proton beam with a circular Gaussian shape of approximately 2{sigma} = 3.5 cm. Two irradiation campaigns were conducted in which samples were exposed for approximately six months and two months, respectively. At the end of this period, the samples were extracted and tested. Activation foils that had been placed in proximity to the materials samples were used to quantify the fluences in various locations. The STAYSL2 code was used to estimate the fluences by combining the activation foil data with calculated data from the LAHET Code System (LCS) and MCNPX. The exposure for each sample was determined from the estimated fluences using interpolation based on a mathematical fitting to the fluence results. The final results included displacement damage (dpa) and gas (H, He) production for each sample from the irradiation. Based on the activation foil analysis, samples from several locations in both irradiation campaigns were characterized. The radiation damage to each sample was highly dependent upon location and varied from 0.023 to 13 dpa and was accompanied by high levels of H and He production
A new image-based tool for the high throughput phenotyping of pollen viability: Evaluation of inter- and intra-cultivar diversity in grapevine
Background: Low pollen viability may limit grapevine yield under certain conditions, causing relevant economic losses to grape-growers. It is usually evaluated by the quantification of the number of viable and non-viable pollen grains that are present in a sample after an adequate pollen grain staining procedure. Although the manual counting of both types of grains is the simplest and most sensitive approach, it is a laborious and time-demanding process. In this regard, novel image-based approaches can assist in the objective, accurate and cost-effective phenotyping of this trait. Results: Here, we introduce PollenCounter, an open-source macro implemented as a customizable Fiji tool for the high-throughput phenotyping of pollen viability. This tool splits RGB images of stained pollen grains into its primary channels, retaining red and green color fractionated images (which contain information on total and only viable pollen grains, respectively) for the subsequent isolation and counting of the regions of interest (pollen grains). This framework was successfully used for the analysis of pollen viability of a high number of samples collected in a large collection of grapevine cultivars. Results revealed a great genetic variability, from cultivars having very low pollen viability (like Corinto Bianco; viability: 14.1 ± 1.3%) to others with a very low presence of sterile pollen grains (Cuelga; viability: 98.2 ± 0.5%). A wide range of variability was also observed among several clones of cv. Tempranillo Tinto (from 97.9 ± 0.9 to 60.6 ± 5.9%, in the first season). Interestingly, the evaluation of this trait in a second season revealed differential genotype-specific sensitivity to environment. Conclusions: The use of PollenCounter is expected to aid in different areas, including genetics research studies, crop improvement and breeding strategies that need of fast, precise and accurate results. Considering its flexibility, it can be used not only in grapevine, but also in other species showing a differential staining of viable and non-viable pollen grains. The wide phenotypic diversity observed at a species level, together with the identification of specific cultivars and clones largely differing in this trait, pave the way of further analyses aimed to understand the physiological and genetic causes driving to male sterility in grapevine. © 2018 The Author(s)