United States Department of Energy

About: United States Department of Energy is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Coal & Catalysis. The organization has 13656 authors who have published 14177 publications receiving 556962 citations. The organization is also known as: DOE & Department of Energy.

Isolation of Succinivibrionaceae Implicated in Low Methane Emissions from Tammar Wallabies

Abstract: The Tammar wallaby (Macropus eugenii) harbors unique gut bacteria and produces only one-fifth the amount of methane produced by ruminants per unit of digestible energy intake. We have isolated a dominant bacterial species (WG-1) from the wallaby microbiota affiliated with the family Succinivibrionaceae and implicated in lower methane emissions from starch-containing diets. This was achieved by using a partial reconstruction of the bacterium's metabolism from binned metagenomic data (nitrogen and carbohydrate utilization pathways and antibiotic resistance) to devise cultivation-based strategies that produced axenic WG-1 cultures. Pure-culture studies confirm that the bacterium is capnophilic and produces succinate, further explaining a microbiological basis for lower methane emissions from macropodids. This knowledge also provides new strategic targets for redirecting fermentation and reducing methane production in livestock.

Identification of safety gaps for fusion demonstration reactors

Abstract: To assist in the development of nuclear fusion as a viable commercial power source, preparation is underway for the fusion demonstration reactor (DEMO), which will build on the work of ITER, the international experimental fusion reactor. Like other advanced nuclear energy systems, DEMO must satisfy several goals including a high level of public and worker safety, low environmental impact, high reactor availability, a closed fuel cycle and the potential to be economically competitive. Yet there are still large scientific and technological safety gaps between the on-going ITER project and DEMO that will need to be addressed. Here we review international fusion safety research and development relevant to DEMO, following the lessons learned so far from ITER. We identify the main scientific and technological safety gaps, drawing on knowledge from the development of fission energy, in particular Generation IV (Gen-IV) fission reactors. From this survey, we discuss the corresponding implications for the design and operation of DEMO. Following on from ITER, a fusion demonstration reactor will be needed to showcase the commercial viability of fusion energy. To guide preliminary design considerations, this Review explores safety gaps that must be filled between current fission reactors, ITER and future fusion reactors.

A parts list for fungal cellulosomes revealed by comparative genomics.

Abstract: Cellulosomes are large, multiprotein complexes that tether plant biomass-degrading enzymes together for improved hydrolysis1. These complexes were first described in anaerobic bacteria, where species-specific dockerin domains mediate the assembly of enzymes onto cohesin motifs interspersed within protein scaffolds1. The versatile protein assembly mechanism conferred by the bacterial cohesin-dockerin interaction is now a standard design principle for synthetic biology2,3. For decades, analogous structures have been reported in anaerobic fungi, which are known to assemble by sequence-divergent non-catalytic dockerin domains (NCDDs)4. However, the components, modular assembly mechanism and functional role of fungal cellulosomes remain unknown5,6. Here, we describe a comprehensive set of proteins critical to fungal cellulosome assembly, including conserved scaffolding proteins unique to the Neocallimastigomycota. High-quality genomes of the anaerobic fungi Anaeromyces robustus, Neocallimastix californiae and Piromyces finnis were assembled with long-read, single-molecule technology. Genomic analysis coupled with proteomic validation revealed an average of 312 NCDD-containing proteins per fungal strain, which were overwhelmingly carbohydrate active enzymes (CAZymes), with 95 large fungal scaffoldins identified across four genera that bind to NCDDs. Fungal dockerin and scaffoldin domains have no similarity to their bacterial counterparts, yet several catalytic domains originated via horizontal gene transfer with gut bacteria. However, the biocatalytic activity of anaerobic fungal cellulosomes is expanded by the inclusion of GH3, GH6 and GH45 enzymes. These findings suggest that the fungal cellulosome is an evolutionarily chimaeric structure-an independently evolved fungal complex that co-opted useful activities from bacterial neighbours within the gut microbiome.

Monte Carlo simulation of single- and binary-component adsorption of CO2, N2, and H2 in zeolite Na-4A

Abstract: We present a molecular model for the adsorption of CO2, N2, H2, and their mixtures in dehydrated zeolite Na-4A. The interatomic potentials for this model were developed by comparing the results of grand canonical Monte Carlo (GCMC) simulations of single-component adsorption at room temperature with experimental measurements. GCMC simulation is also used to assess the adsorption selectivity of CO2/N2 and CO2/H2 mixtures, as a function of temperature and gas-phase composition. At room temperature, Na-4A is strongly selective for CO2 over both N2 and H2, although this selectivity decreases slightly as the gas-phase pressure increases. Ideal adsorbed solution theory is shown to give accurate predictions of the adsorption selectivity at low CO2 partial pressures, provided that a functional form that accurately describes the CO2 single-component isotherm is used. The adsorption properties of CO2/N2 mixtures in Na-4A are compared to the same mixtures in silicalite.

Plutonium in the Environment—A Review

Abstract: The plutonium that will be produced in the nuclear fuel cycle is a matter of extreme importance to regulators and to members of the public concerned with the environment. At the present time there is plutonium present in the environment on a global scale from weapons testing and from a satellite failure and on a local scale from nuclear operations and from the loss of nuclear weapons. The sensitivity of plutonium measurement has allowed us to study the present environmental levels of plutonium in the atmosphere, on the ground, in the oceans and in the pathways leading to man. This information, in turn, may allow us to predict the probable distribution of this material from any future contamination. Since the present levels from even local contamination are low, it is desirable to be able to distinguish among the various sources, particularly distinguishing local sources from global fallout. When plutonium-238 is involved, alpha spectrometry can provide the contribution from this source. When the question involves the 239/240 ratio, mass spectrometry is necessary and only very high quality mass spectrometry is adequate for environmental levels of plutonium. This paper will review our present knowledge of environmental plutonium and give some examples of problems where it has been necessary to distinguish among the various plutonium isotopes.