FY2010 Annual Report for the Actinide Isomer Detection Project

This project seeks to identify a new signature for actinide element detection in active interrogation. This technique works by exciting and identifying long-lived nuclear excited states (isomers) in the actinide isotopes and/or primary fission products. Observation of isomers in the fission products will provide a signature for fissile material. For the actinide isomers, the decay time and energy of the isomeric state is unique to a particular isotope, providing an unambiguous signature for Special Nuclear Materials (SNM). Future work will include a follow-up measurement scheduled for December 2010 at LBNL. Lessons learned from the July 2010 measurements will be incorporated into these new measurements. Analysis of both the July and December experiments will be completed in a few months. A research paper to be submitted to a peer-reviewed journal will be drafted if the conclusions from the measurements warrant publication

A somatic coliphage threshold approach to improve the management of activated sludge wastewater treatment plant effluents in resource-limited regions

Versión aceptada para publicaciónEffective wastewater management is crucial to ensure the safety of water reuse projects and 29 effluent discharge into surface waters. Multiple studies have demonstrated that municipal 30 wastewater treatment with conventional activated sludge processes is inefficient for the removal 31 of the wide spectrum of viruses in sewage. In this study, a well-accepted statistical approach was 32 used to investigate the relationship between viral indicators and human enteric viruses during 33 wastewater treatment in a resource-limited region. Influent and effluent samples from five urban 34 wastewater treatment plants (WWTP) in Costa Rica were analyzed for somatic coliphage and 35 human enterovirus, hepatitis A virus, norovirus genotype I and II, and rotavirus. All WWTP 36 provide primary treatment followed by conventional activated sludge treatment prior to 37 discharge into surface waters that are indirectly used for agricultural irrigation. The results 38 revealed a statistically significant relationship between the detection of at least one of the five 39 human enteric viruses and somatic coliphage. Multiple logistic regression and Receiver Operating Characteristic curve analysis identified a threshold of 3.0 ×103 40 (3.5-log10) somatic 41 coliphage plaque forming unit per 100 mL, which corresponded to an increased likelihood of encountering enteric viruses above the limit of detection (>1.83×102 42 virus target/100 mL). 43 Additionally, quantitative microbial risk assessment was executed for famers indirectly reusing 44 WWTP effluent that met the proposed threshold. The resulting estimated median cumulative 45 annual disease burden complied with World Health Organization recommendations. Future 46 studies are needed to validate the proposed threshold for use in Costa Rica and other regions.Universidad de Costa Rica/[]/UCR/Costa RicaNational Science Foundation/[OCE-1566562]/NSF/Estados UnidosUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto de Investigaciones en Salud (INISA)UCR::Vicerrectoría de Docencia::Salud::Facultad de Microbiologí

Cryo-EM Studies of Drp1 Reveal Cardiolipin Interactions that Activate the Helical Oligomer

Abstract Dynamins are mechano-chemical GTPases involved in the remodeling of cellular membranes. In this study, we have investigated the mechanism of dynamin-related protein 1 (Drp1), a key mediator of mitochondrial fission. To date, it is unclear how Drp1 assembles on the mitochondrial outer membrane in response to different lipid signals to induce membrane fission. Here, we present cryo-EM structures of Drp1 helices on nanotubes with distinct lipid compositions to mimic membrane interactions with the fission machinery. These Drp1 polymers assemble exclusively through stalk and G-domain dimerizations, which generates an expanded helical symmetry when compared to other dynamins. Interestingly, we found the characteristic gap between Drp1 and the lipid bilayer was lost when the mitochondrial specific lipid cardiolipin was present, as Drp1 directly interacted with the membrane. Moreover, this interaction leads to a change in the helical structure, which alters G-domain interactions to enhance GTPase activity. These results demonstrate how lipid cues at the mitochondrial outer membrane (MOM) can alter Drp1 structure to activate the fission machinery

Fiscal Year 2010

This project seeks to identify a new signature for actinide element detection in active interrogation. This technique works by exciting and identifying long-lived nuclear excited states (isomers) in the actinide isotopes and/or primary fission products. Observation of isomers in the fission products will provide a signature for fissile material. For the actinide isomers, the decay time and energy of the isomeric state is unique to a particular isotope, providing an unambiguous signature for Special Nuclear Materials (SNM). Future work will include a follow-up measurement scheduled for December 2010 at LBNL. Lessons learned from the July 2010 measurements will be incorporated into these new measurements. Analysis of both the July and December experiments will be completed in a few months. A research paper to be submitted to a peer-reviewed journal will be drafted if the conclusions from the measurements warrant publication

FY2010 Annual Report for the Actinide Isomer Detection Project

This project seeks to identify a new signature for actinide element detection in active interrogation. This technique works by exciting and identifying long-lived nuclear excited states (isomers) in the actinide isotopes and/or primary fission products. Observation of isomers in the fission products will provide a signature for fissile material. For the actinide isomers, the decay time and energy of the isomeric state is unique to a particular isotope, providing an unambiguous signature for Special Nuclear Materials (SNM). Future work will include a follow-up measurement scheduled for December 2010 at LBNL. Lessons learned from the July 2010 measurements will be incorporated into these new measurements. Analysis of both the July and December experiments will be completed in a few months. A research paper to be submitted to a peer-reviewed journal will be drafted if the conclusions from the measurements warrant publication

Fiscal Year 2011

This project seeks to identify a new signature for actinide element detection in active interrogation. This technique works by exciting and identifying long-lived nuclear excited states (isomers) in the actinide isotopes and/or primary fission products. Observation of isomers in the fission products will provide a signature for fissile material. For the actinide isomers, the decay time and energy of the isomeric state is unique to a particular isotope, providing an unambiguous signature for SNM. This project entails isomer identification and characterization and neutron population studies. This document summarizes activities from its third year - completion of the isomer identification characterization experiments and initialization of the neutron population experiments. The population and decay of the isomeric state in 235U remain elusive, although a number of candidate gamma rays have been identified. In the course of the experiments, a number of fission fragment isomers were populated and measured [Ressler 2010]. The decays from these isomers may also provide a suitable signature for the presence of fissile material. Several measurements were conducted throughout this project. This report focuses on the results of an experiment conducted collaboratively by PNNL, LLNL and LBNL in December 2010 at LBNL. The measurement involved measuring the gamma-rays emitted from an HEU target when bombarded with 11 MeV neutrons. This report discussed the analysis and resulting conclusions from those measurements. There was one strong candidate, at 1204 keV, of an isomeric signature of 235U. The half-life of the state is estimated to be 9.3 {mu}s. The measured time dependence fits the decay time structure very well. Other possible explanations for the 1204-keV state were investigated, but they could not explain the gamma ray. Unfortunately, the relatively limited statistics of the measurement limit, and the lack of understanding of some of the systematic of the experiment, limit the authors to labeling the 1204-keV gamma ray as a very strong candidate for isomeric transition in 235U. Regardless of the physics origins, the time structure of the 1204-keV gamma ray can be used as at a minimum as an indication of fissile material, if the 1204-keV gamma ray is attributed to a fission product, or it may be a unique signature for 235U, if it is a signature of an isomeric state in 235U