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.

Complete sequences of the highly rearranged molluscan mitochondrial genomes of the Scaphopod Graptacme eborea and the bivalve Mytilus edulis.

Abstract: We have determined the complete sequence of the mitochondrial genome of the scaphopod mollusk Graptacme eborea (14,492 nts) and completed the sequence of the mitochondrial genome of the bivalve mollusk Mytilus edulis (16,740 nts). (The name Graptacme eborea is a revision of the species formerly known as Dentalium eboreum.) G. eborea mtDNA contains the 37 genes that are typically found and has the genes divided about evenly between the two strands, but M. edulis contains an extra trnM and is missing atp8, and it has all genes on the same strand. Each has a highly rearranged gene order relative to each other and to all other studied mtDNAs. G. eborea mtDNA has almost no strand skew, but the coding strand of M. edulis mtDNA is very rich in G and T. This is reflected in differential codon usage patterns and even in amino acid compositions. G. eborea mtDNA has fewer noncoding nucleotides than any other mtDNA studied to date, with the largest noncoding region only 24 nt long. Phylogenetic analysis using 2,420 aligned amino acid positions of concatenated proteins weakly supports an association of the scaphopod with gastropods to the exclusion of Bivalvia, Cephalopoda, and Polyplacophora, but it is generally unable to convincingly resolve the relationships among major groups of the Lophotrochozoa, in contrast to the good resolution seen for several other major metazoan groups.

Fluid dynamic simulation of O3 decomposition in a bubbling fluidized bed

Abstract: Recent advances in dense, multiphase, computational fluid dynamics (CFD) have allowed accurate simulation of the gas and particle motion in bubbling and circulating fluidized beds. Since fluidized-bed reactors are used for many chemical processes, a simulation must also be able to accurately couple chemical reactions to bed hydrodynamics. The catalytic decomposition of ozone (O 3 ) often has been used to study experimentally the contacting behavior of catalytic reactors. Simulations of laboratory-scale experiments of premixed O 3 decomposition in a bubbling fluidized bed using the multiphase CFD code MFIX were conducted. The grid-independent results are in very good agreement with reported experimental data on total conversion over a range of fluidization velocities and initial bed heights. This confirms the ability of multiphase hydrodynamic models to capture quantitatively the effect of hydrodynamics on chemical reactions in a bubbling fluidized bed.

Selection and treatment of data for radiocarbon calibration: an update to the international calibration (intcal) criteria

Abstract: High-quality data from appropriate archives are needed for the continuing improvement of radiocarbon cali- bration curves. We discuss here the basic assumptions behind 14C dating that necessitate calibration and the relative strengths and weaknesses of archives from which calibration data are obtained. We also highlight the procedures, problems, and uncer- tainties involved in determining atmospheric and surface ocean 14C/12C in these archives, including a discussion of the vari- ous methods used to derive an independent absolute timescale and uncertainty. The types of data required for the current IntCal database and calibration curve model are tabulated with examples.

Power-System Frequency and Stability Control using Decentralized Intelligent Loads

Abstract: Modern power systems operate on the premise that the load is uncontrollable and that system voltage, frequency and stability are primarily maintained through control of the generation. In this paper, we challenge this premise by proposing a much more active role for intelligent loads specifically related to frequency control and dynamic stability. In modern systems the load is typically only controlled under severe stability conditions via load shedding. Recent research has demonstrated that many loads could cost-effectively become intelligent, allowing for the potential of the loads to more actively participate in system operation and control. The potential benefits of active load control are investigated. Also, reliability and implementation issues are explored. Fundamental analysis and multi-machine system simulation examples are used to demonstrate many of the issues