Bench scale (1 to 6 gram) methane cracking tests have been performed on a variety of pure elements, some alloys, and SAES{reg_sign} commercial getters St 101, St 198, St 707, St 737, and St 909 to determine methane cracking performance (MCP) of 5% methane in a helium carrier at 700 C, 101.3 kPa (760 torr) with a 10 sccm feed. The MCP was almost absent from some materials tested while others showed varying degrees of MCP. Re, Cr, V, Gd, and Mo powders had good MCP, but limited capacities. Nickel supported on kieselguhr (Ni/k), a Zr-Ni alloy, and the SAES{reg_sign} getters had good MCP in a helium carrier. The MCP of these same materials was suppressed in a hydrogen carrier stream and the MCP of the Zr-based materials was reduced by nitride formation when tested with a nitrogen carrier gas.

Brookhaven National Laboratory continues its multi-year program to improve the operational efficiency, reliability, and stability of the cryogenic system which also resulted in improved beam availability of the Relativistic Heavy Ion Collider (RHIC). This paper summarizes the work and changes made after each phase over the past four years to the present, as well as proposed future improvements. Power usage dropped from an initial 9.4 MW to the present 5.1 MW and is expected to drop below 5 MW after the completion of the remaining proposed improvements. The work proceeded in phases by balancing the Collider's schedule of operation, time required for the modifications and budget constraints. The main changes include process control, compressor oil removal and management, elimination of the use of cold compressors and two liquid helium storage tanks, insulation of the third liquid helium storage tank, compressor bypass flow reduction and the addition of a load turbine (Joule-Thompson expander) with associated heat exchangers at the cold end of the plant. Also, liquid helium pumps used for forced circulation of the sub-cooled helium through the magnet loops were eliminated by an accelerator supply flow reconfiguration. Planned future upgrades include the resizing of expanders 5 and 6 to increase …

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Polymer Nanocomposites are an important class of nanomaterials with potential applications including but not limited to structural and cushion materials, electromagnetic and heat shields, conducting plastics, sensors, and catalysts for various chemical and bio processes. Success in most such applications hinges on molecular-level control of structure and assembly, and a deep understanding of how the overall morphology of various components and the interfaces between them affect the composite properties at the macroscale. The length and time-scales associated with such assemblies are prohibitively large for a full atomistic modeling. Instead we adopt a multiscale methodology in which atomic-level interactions between different components of a composite are incorporated into a coarse-grained simulation of the mesoscale morphology, which is then represented on a numerical grid and the macroscopic properties computed using a finite-elements method.

Obesity is increasing in an epidemic fashion in most countries and constitutes a public health problem by enhancing the risk for cardiovascular disease and metabolic disorders such as type 2 diabetes. Owing to the increase in obesity, life expectancy may start to decrease in developed countries for the first time in recent history. The factors determining fat mass in adult humans are not fully understood, but increased lipid storage in already developed fat cells is thought to be most important. We show that adipocyte number is a major determinant for the fat mass in adults. However, the number of fat cells stays constant in adulthood in lean and obese and even under extreme conditions, indicating that the number of adipocytes is set during childhood and adolescence. To establish the dynamics within the stable population of adipocytes in adults, we have measured adipocyte turnover by analyzing the integration of {sup 14}C derived from nuclear bomb tests in genomic DNA. Approximately 10% of fat cells are renewed annually at all adult ages and levels of body mass index. Neither adipocyte death nor generation rate is altered in obesity, suggesting a tight regulation of fat cell number that is independent of metabolic profile …

Numerical tests are used to validate a practical estimatefor the optimal backward errors of linear least squares problems. Thissolves a thirty-year-old problem suggested by Stewart andWilkinson.

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Dissolution and precipitation rates of low defect Georgia kaolinite (KGa-1b) as a function of Gibbs free energy of reaction (or reaction affinity) were measured at 22 C and pH 4 in continuously stirred flow through reactors. Steady state dissolution experiments showed slightly incongruent dissolution, with a Si/Al ratio of about 1.12 that is attributed to the re-adsorption of Al on to the kaolinite surface. No inhibition of the kaolinite dissolution rate was apparent when dissolved aluminum was varied from 0 and 60 {micro}M. The relationship between dissolution rates and the reaction affinity can be described well by a Transition State Theory (TST) rate formulation with a Temkin coefficient of 2 R{sub diss} (mol/m{sup 2}s) = 1.15 x 10{sup -13} [1-exp(-{Delta}G/2RT)]. Stopping of flow in a close to equilibrium dissolution experiment yielded at solubility constant for kaolinite at 22 C of 10{sup 7.57}. Experiments on the precipitation kinetics of kaolinite showed a more complex behavior. One conducted using kaolinite seed that had previously undergone extensive dissolution under far from equilibrium conditions for 5 months showed a quasi-steady state precipitation rate for 105 hours that was compatible with the TST expression above. After this initial period, however, precipitation rates decreased by an …

Comprehensive test ban monitoring in terms of location and discrimination has progressed significantly in recent years. However, the characterization of sources and the estimation of low yields remains a particular challenge. As the recent Korean shot demonstrated, we can probably expect to have a small set of teleseismic, far-regional and high-frequency regional data to analyze in estimating the yield of an event. Since stacking helps to bring signals out of the noise, it becomes useful to conduct comparable analyses on neighboring events, earthquakes in this case. If these auxiliary events have accurate moments and source descriptions, we have a means of directly comparing effective source strengths. Although we will rely on modeling codes, 1D, 2D, and 3D, we will also apply a broadband calibration procedure to use longer periods (P>5s) waveform data to calibrate short-period (P between .5 to 2 Hz) and high-frequency (P between 2 to 10 Hz) as path specify station corrections from well-known regional sources. We have expanded our basic Cut-and-Paste (CAP) methodology to include not only timing shifts but also amplitude (f) corrections at recording sites. The name of this method was derived from source inversions that allow timing shifts between 'waveform segments' (or cutting the …

The electronic structure of cobalt nanocrystals suspended in liquid as a function of size has been investigated using in-situ x-ray absorption and emission spectroscopy. A sharp absorption peak associated with the ligand molecules is found that increases in intensity upon reducing the nanocrystal size. X-ray Raman features due to d-d and to charge-transfer excitations of ligand molecules are identified. The study reveals the local symmetry of the surface of {var_epsilon}-Co phase nanocrystals, which originates from a dynamic interaction between Co nanocrystals and surfactant + solvent molecules.

Accelerators are the largest and most costly scientific instruments of the Department of Energy, with uses across a broad range of science, including colliders for particle physics and nuclear science and light sources and neutron sources for materials studies. COMPASS, the Community Petascale Project for Accelerator Science and Simulation, is a broad, four-office (HEP, NP, BES, ASCR) effort to develop computational tools for the prediction and performance enhancement of accelerators. The tools being developed can be used to predict the dynamics of beams in the presence of optical elements and space charge forces, the calculation of electromagnetic modes and wake fields of cavities, the cooling induced by comoving beams, and the acceleration of beams by intense fields in plasmas generated by beams or lasers. In SciDAC-1, the computational tools had multiple successes in predicting the dynamics of beams and beam generation. In SciDAC-2 these tools will be petascale enabled to allow the inclusion of an unprecedented level of physics for detailed prediction.

Motivated by recent experiments, numerical simulations were performed of cylindrically converging shock waves. The converging shocks impinged upon a set of zero to sixteen regularly space obstacles. For more than two obstacles the resulting diffracted shock fronts formed polygonal shaped patterns near the point of focus. The maximum pressure and temperature as a function of number of obstacles were studied. The self-similar behavior of cylindrical, triangular and square-shaped shocks were also investigated.

Physical constraints such as power, leakage and pin bandwidth are currently driving the HPC industry to produce systems with unprecedented levels of concurrency. In these parallel systems, synchronization and memory operations are becoming considerably more expensive than before. In this work we study parallel matrix factorization codes and conclude that they need to be re-engineered to avoid unnecessary (and expensive) synchronization. We propose the use of multithreading combined with intelligent schedulers and implement representative algorithms in this style. Our results indicate that this strategy can significantly outperform traditional codes.

There is an ongoing disagreement regarding the aging of the shortfin mako due to a difference of interpretation in the periodic deposition of vertebral growth band pairs, especially for the larger size classes. Using analysis of length-month information, tagging data, and length-frequency analysis, concluded that two band pairs were formed in the vertebral centrum every year (biannual band-pair interpretation). Cailliet et al. (1983), however, presented growth parameters based on the common assumption that one band pair forms annually (annual band-pair interpretation). Therefore, growth rates obtained by Pratt & Casey (1983) were twice that of Cailliet et al. (1983) and could lead to age discrepancies of about 15 years for maximum estimated ages on the order of 30 from the annual band-pair interpretation. Serious consequences in the population dynamics could occur for this species if inputs are based on an invalid age interpretation. The latest Fishery Management Plan (FMP) for Highly Migratory Species (HMS), for example, adopted the biannual band pair deposition hypothesis because it apparently fit the observed growth patterns best (Pacific Fishery Management Council 2003). However, the ongoing uncertainty about the aging of the shortfin mako was acknowledged and it was recommended that an endeavor to resolve this issue …

The ordering of liquid crystalline polymer fiber during heat treatment is of great interest for many commercial reasons. This is because, by convention, fiber property can be greatly improved by heat-treatment at below the melting temperature and often such processing conditions are also very complex. There are many variations of such treatments, in terms of temperature, exposure time and whether the fibers are under tension or not. The state-of-the-art technology will be to optimize the desired property without significantly enhancing the undesired properties. The types of heat treatment are highly correlated to the understanding of the mechanism of improving the properties at the molecular level and the microstructures. Using WAXS and synchrotron SAXS techniques, the structure and morphology of our commercial LCP (liquid crystalline polymer), a co-polymer of CO (Vectran) and its variant polymer fiber COTHBP are being examined. Both fibers have the typical liquid crystalline polymer structure, ie, highly ordered across the fiber axis and aperiodic sequencing along the fiber axis. Physical testing has revealed a three fold increase in strength in both fibers, however, the modulus is observed to increase significantly in COTBP and not so much CO. This paper reports on the changes and the differences on …