ANODIC BEHAVIOR OF ALLOY 22 IN HIGH NITRATE BRINES AT TEMPERATURES HIGHER THAN 100C

Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100 C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100 C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160 C at ambient atmospheres. Even though Alloy 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100 C

LONG-TERM CORROSION TESTING OF CANDIDATE MATERIALS FOR HIGH-LEVEL RADIOACTIVE WASTE CONTAINMENT

Preliminary results are presented from the long-term corrosion test program of candidate materials for the high-level radioactive waste packages that would be emplaced in the potential repository at Yucca Mountain, Nevada. The present waste package design is based on a multi-barrier concept having an inner container of a corrosion resistant material and an outer container of a corrosion allowance material. Test specimens have been exposed to simulated bounding environments that may credibly develop in the vicinity of the waste packages. Corrosion rates have been calculated for weight loss and crevice specimens, and U-bend specimens have been examined for evidence of stress corrosion cracking (SCC). Galvanic testing has been started recently and initial results are forthcoming. Pitting characterization of test specimens will be conducted in the coming year. This test program is expected to continue for a minimum of five years so that long-term corrosion data can be determined to support corrosion model development, performance assessment, and waste package design

Prioritizing Species by Conservation Value and Vulnerability: A New Index Applied to Species Threatened by Sea-Level Rise and Other Risks in Florida

Land-use change, climate change, and sea-level rise (SLR) pose substantial threats to biodiversity. Conservation resources are limited and must be directed toward the species and ecosystems that are most vulnerable, biologically distinct, likely to respond favorably to conservation interventions, and valuable ecologically, socially, or economically. Many prioritization and vulnerability assessment schemes exist, each emphasizing different types of vulnerabilities and values and often yielding disparate evaluations of the same species. We developed an integrative and flexible framework that incorporates existing assessments and is useful for illuminating the differences between systems such as the IUCN Red List, the US Endangered Species Act, and NatureServe\u27s Conservation Status Assessment and Climate Change Vulnerability Index. The Standardized Index of Vulnerability and Value Assessment (SIVVA) includes five advancements over existing tools: (1) the ability to import criteria and data from previous assessments, (2) explicit attention to SLR, (3) a flexible system of scoring, (4) metrics for both vulnerability and conservation value, and (5) quantitative and transparent accounting of multiple sources of uncertainty. We apply this system to 40 species in Florida previously identified as being vulnerable to SLR by the year 2100, describe the influence of different types of uncertainty on the resulting prioritizations, and explore the power of SIVVA to evaluate alternative prioritization schemes. This type of assessment is particularly relevant in low-lying coastal regions where vulnerability to SLR is predictable, severe, and likely to interact synergistically with other threats such as coastal development

The B73 Maize Genome: Complexity, Diversity, and Dynamics

We report an improved draft nucleotide sequence of the 2.3-gigabase genome of maize, an important crop plant and model for biological research. Over 32,000 genes were predicted, of which 99.8% were placed on reference chromosomes. Nearly 85% of the genome is composed of hundreds of families of transposable elements, dispersed nonuniformly across the genome. These were responsible for the capture and amplification of numerous gene fragments and affect the composition, sizes, and positions of centromeres. We also report on the correlation of methylation-poor regions with Mu transposon insertions and recombination, and copy number variants with insertions and/or deletions, as well as how uneven gene losses between duplicated regions were involved in returning an ancient allotetraploid to a genetically diploid state. These analyses inform and set the stage for further investigations to improve our understanding of the domestication and agricultural improvements of maize