Rapid assessment of sweetpotato seed and root production and markets in Kamuli and Iganga districts, near Eastern Uganda

The International Potato Center (CIP) and National Crops Resources Research Institute (NaCRRI) under the supervision of National Agricultural Research Organization are implementing a three-year project entitled, ‘Sweetpotato Genetic Advances and Innovative Seed Systems (SweetGAINS)’ funded by Bill and Melinda Gates Foundation (BMGF). The project aims to modernize the current Sweetpotato breeding systems and early generation seed production. SweetGAINS project is structured into work packages (WP1 - WP4) for effective and efficient implementation. As part of work package 4, a detailed rapid assessment of the sweetpotato seed system was conducted. The main objective of the study was to generate bench information to support the implementation of the sweetpotato system

Identification of simple sequence repeat markers for sweetpotato weevil resistance

The development of sweetpotato [Ipomoea batatas (L.) Lam] germplasm with resistance to sweetpotato weevil (SPW) requires an understanding of the biochemical and genetic mechanisms of resistance to optimize crop resistance. The African sweetpotato landrace, ‘New Kawogo’, was reported to be moderately resistant to two species of SPW, Cylas puncticollis and Cylas brunneus. Resistance has been associated with the presence of hydroxycinnamic acids esters (HCAs), but the underlying genetic basis remains unknown. To determine the genetic basis of this resistance, a bi-parental sweetpotato population from a cross between the moderately resistant, white-fleshed ‘New Kawogo’ and the highly susceptible, orange-fleshed North American variety ‘Beauregard’ was evaluated for SPW resistance and genotyped with simple sequence repeat (SSR) markers to identify weevil resistance loci. SPW resistance was measured on the basis of field storage root SPW damage severity and total HCA ester concentrations. Moderate broad sense heritability (H2 = 0.49) was observed for weevil resistance in the population. Mean genotype SPW severity scores ranged from 1.0 to 9.0 and 25 progeny exhibited transgressive segregation for SPW resistance. Mean genotype total HCA ester concentrations were significantly different (P < 0.0001). A weak but significant correlation (r = 0.103, P = 0.015) was observed between total HCA ester concentration and SPW severity. A total of five and seven SSR markers were associated with field SPW severity and total HCA ester concentration, respectively. Markers IBS11, IbE5 and IbJ544b showed significant association with both field and HCA-based resistance, representing potential markers for the development of SPW resistant sweetpotato cultivars

Fusion transmutation of waste: design and analysis of the in-zinerator concept.

Due to increasing concerns over the buildup of long-lived transuranic isotopes in spent nuclear fuel waste, attention has been given in recent years to technologies that can burn up these species. The separation and transmutation of transuranics is part of a solution to decreasing the volume and heat load of nuclear waste significantly to increase the repository capacity. A fusion neutron source can be used for transmutation as an alternative to fast reactor systems. Sandia National Laboratories is investigating the use of a Z-Pinch fusion driver for this application. This report summarizes the initial design and engineering issues of this ''In-Zinerator'' concept. Relatively modest fusion requirements on the order of 20 MW can be used to drive a sub-critical, actinide-bearing, fluid blanket. The fluid fuel eliminates the need for expensive fuel fabrication and allows for continuous refueling and removal of fission products. This reactor has the capability of burning up 1,280 kg of actinides per year while at the same time producing 3,000 MWth. The report discusses the baseline design, engineering issues, modeling results, safety issues, and fuel cycle impact

The Material Characterization and Gamma Attenuation Properties of Portland Cement-Fe₃O₄ Composites for Potential Dry Cask Applications

The effect of nanosized magnetite (Fe3O4) additions on the microstructural, mechanical and gamma attenuation properties of White Ordinary Portland cement (WOPC) pastes was investigated. The microstructure of a set of cement composites with Fe3O4 content ranging from 0 to 50 wt% was examined using X-ray diffraction and Scanning Electron Microscopy (SEM) techniques. Magnetite additions did not influence the hydration products of Portland cement after 28 days of curing. SEM showed uniform distribution of magnetite nanoparticles in the cement hydration products of composites with less than 10 wt% Fe3O4. Aggregation of magnetite nanoparticles occurred when high loading of magnetite was added to the cement (20, 40 and 50 wt%). Compressive strength and stress-strain curves were also measured to characterize the mechanical performance of the composites. A maximum compressive strength of 60 MPa was obtained for cement pastes reinforced with 10 wt% Fe3O4, which represents an enhancement of 50% over the plain WPOC paste. Composites loaded with 50 wt% Fe3O4 yielded to a reduction of compressive strength (35 MPa) of 5% over the reference paste. Mechanical behavior of the material was explained in terms of their microstructure, i.e. uniform magnetite embedded in the paste has a reinforcement effect due to the promotion of hydration process and the filling effect of the particles. Heterogeneous distribution of magnetite particles due to agglomeration acted to weaken the cementitious matrix by creation of pores. Finally, transmission experiments and Monte Carlo simulations were conducted to evaluate the shielding properties of the composites when exposed to a Cs-137 gamma source (0.662 MeV). The addition of Fe3O4 improves the shielding capability of Portland cement pastes with enhancements ranging between 3.1 and 2.6% for samples with 2.5 and 50 wt% Fe3O4 respectively. No simple relationship exists between the attenuation properties and magnetite loading. Changes in the attenuation coefficients of the composites are explained in terms of the chemical composition and microstructural effects