The durability of natural glasses on geological time scales and ancient glasses for thousands of years is well documented. The necessity to predict the durability of high level nuclear waste (HLW) glasses on extended time scales has led to various thermodynamic and kinetic approaches. Advances in the measurement of medium range order (MRO) in glasses has led to the understanding that the molecular structure of a glass, and thus the glass composition, controls the glass durability by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. During the early stages of glass dissolution, a 'gel' layer resembling a membrane forms through which ions exchange between the glass and the leachant. The hydrated gel layer exhibits acid/base properties which are manifested as the pH dependence of the thickness and nature of the gel layer. The gel layer ages into clay or zeolite minerals by Ostwald ripening. Zeolite mineral assemblages (higher pH and Al{sup 3+} rich glasses) may cause the dissolution rate to increase which is undesirable for long-term performance of glass in the environment. Thermodynamic and structural approaches to the prediction of glass durability are compared versus Ostwald ripening.

Biodiesel is a mixture of long chain fatty acid methyl esters derived from fats and oils. This research study presents opposed-flow diffusion flame data for one large fatty acid methyl ester, methyl decanoate, and uses the experiments to validate an improved skeletal mechanism consisting of 648 species and 2998 reactions. The results indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene.

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Article showing that the enhanced growth and NAE tolerance of the AtFAAH overexpressing seedlings depends on the catalytic activity of AtFAAH, hypersensitivity to ABA and hypersusceptibility to nonhost pathogens are independent of its enzymatic activity. Findings suggest that the AtFAAH influences plant growth and interacts with ABA signaling and plant defense through distinctly different mechanisms.

The aligned nanorods of Co{sub 3}O{sub 4} and nanoporous hollow spheres (NHS) of SnO{sub 2} and Mn{sub 2}O{sub 3} were investigated as the anodes for Li-ion rechargeable batteries. The Co{sub 3}O{sub 4} nanorods demonstrated 1433 mAh/g reversible capacity. The NHS of SnO{sub 2} and Mn{sub 2}O{sub 3} delivered 400 mAh/g and 250 mAh/g capacities respectively in multiple galvonastatic discharge-charge cycles. It was found that high capacity of NHS of metal oxides is sustainable attributed to their unique structure that maintains material integrity during cycling. The nanostructured metal oxides exhibit great potential as the new anode materials for Li-ion rechargeable batteries with high energy density, low cost and inherent safety.

We study the relative ability of several models of the X-ray absorption spectrum to capture the Franck-Condon structure apparent from an experiment on gaseous nitrogen. In doing so, we adopt the Born-Oppenheimer approximation and a constrained density functional theory method for computing the energies of the X-ray-excited molecule. Starting from an otherwise classical model for the spectrum, we systematically introduce more realistic physics, first by substituting the quantum mechanical nuclear radial density in the bond separation R for the classical radial density, then by adding the effect of zero-point energy and other level shifts, and finally by including explicit rovibrational quantization of both the ground and excited states. The quantization is determined exactly, using a discrete variable representation. We show that the NEXAFS spectrum can be predicted semiquantiatively within this framework. We also address the possibility of non-trivial temperature dependence in the spectrum. Finally, we show that it is possible to improve the predicted spectrum by using constrained DFT in combination with more accurate potentials.

The program of the 25th Rare Earth Research Conference (RERC08) integrated basic and applied multidisciplinary research centered on the f-elements. Leading science was featured in the form of invited oral presentations and contributed posters on topics in f-element chemistry, physics, and material, earth, environmental, and biological sciences. The conference was held in Shelby Hall, located on The University of Alabama?s Tuscaloosa, AL campus. The final program and list of attendees is available at URL http://bama.ua.edu/~rdrogers/RERC08/.

A hard/soft SmCo{sub 5}/Fe nanocomposite magnetic bilayer system has been fabricated on X-ray transparent 100-200 nm thin Si{sub 3}N{sub 4} membranes by magnetron sputtering. The microscopic magnetic domain pattern and its behavior during magnetization reversal in the hard and soft magnetic phases have been individually studied by element specific magnetic soft x-ray microscopy at a spatial resolution of better than 25nm. We observe that the domain patterns for soft and hard phases switch coherently throughout the full hysteresis cycle upon applying external magnetic fields. We derived local M(H) curves from the images for Fe and SmCo5 separately and found switching for both hard and soft phases same.

This article describes the extraction of three-dimensional functional group patterns responsible for binding CO₂ from the few protein-CO₂ complexes that have been characterized by X-ray crystallography.

We simulate long-period (T > 1.0-2.0 s) and broadband (T > 0.1 s) ground motions for 39 scenarios earthquakes (Mw 6.7-7.2) involving the Hayward, Calaveras, and Rodgers Creek faults. For rupture on the Hayward fault we consider the effects of creep on coseismic slip using two different approaches, both of which reduce the ground motions compared with neglecting the influence of creep. Nevertheless, the scenario earthquakes generate strong shaking throughout the San Francisco Bay area with about 50% of the urban area experiencing MMI VII or greater for the magnitude 7.0 scenario events. Long-period simulations of the 2007 Mw 4.18 Oakland and 2007 Mw 4.5 Alum Rock earthquakes show that the USGS Bay Area Velocity Model version 08.3.0 permits simulation of the amplitude and duration of shaking throughout the San Francisco Bay area, with the greatest accuracy in the Santa Clara Valley (San Jose area). The ground motions exhibit a strong sensitivity to the rupture length (or magnitude), hypocenter (or rupture directivity), and slip distribution. The ground motions display a much weaker sensitivity to the rise time and rupture speed. Peak velocities, peak accelerations, and spectral accelerations from the synthetic broadband ground motions are, on average, slightly higher than the …

A two-color two-photon atomic double ionization experiment using subfemtosecond UV pulses can be designed such that the sequential two-color process dominates and one electron is ejected by each pulse. Nonetheless, ab initio calculations show that, for sufficiently short pulses, a prominent interference pattern in the joint energy distribution of the sequentially ejected electrons can be observed that is due to their indistinguishability and the exchange symmetry of the wave function.

Numerical integration errors and volumetric locking in the near-incompressible limit are two outstanding issues in Galerkin-based meshfree computations. In this paper, we present a modified Gaussian integration scheme on background cells for meshfree methods that alleviates errors in numerical integration and ensures patch test satisfaction to machine precision. Secondly, a locking-free small-strain elasticity formulation for meshfree methods is proposed, which draws on developments in assumed strain methods and nodal integration techniques. In this study, maximum-entropy basis functions are used; however, the generality of our approach permits the use of any meshfree approximation. Various benchmark problems in two-dimensional compressible and near-incompressible small strain elasticity are presented to demonstrate the accuracy and optimal convergence in the energy norm of the maximum-entropy meshfree formulation.

Neutron Imaging is a key diagnostic for use in inertial confinement fusion (ICF) experiments, and has been fielded on experiments at Omega and Z. It will also be a key diagnostics at the National Ignition Facility (NIF) located at Lawrence Livermore National Laboratory (LLNL) and eventually at the Laser Megajoule in France. Most systems are based on a neutron pinhole array placed at the target chamber while it is imaged by a scintillating fiber block. The light output of this scintillator is coupled via a reducer to a fiber bundle which transports the image to a CCD camera. Alternatively some systems use optical lens assemblies to focus the light onto a camera.For ICF applications the neutron imaging systems will primarily look at 14.2 MeV neutrons. However, 2.2 MeV and 20+ MeV neutrons will also be present and will potentially provide key information.

Biologically synthesized magnetite (Fe{sub 3}O{sub 4}) nanoparticles are studied using x-ray absorption and x-ray magnetic circular dichroism following exposure to hexavalent Cr solution. By examining their magnetic state, Cr cations are shown to exist in trivalent form on octahedral sites within the magnetite spinel surface. The possibility of reducing toxic Cr(VI) into a stable, non-toxic form, such as a Cr{sup 3+}-spinel layer, makes biogenic magnetite nanoparticles an attractive candidate for Cr remediation.

The Neutron Imager diagnostic at the National Ignition Facility (NIF) located at Lawrence Livermore National Laboratory (LLNL) will produce high-resolution, gated images of neutron-generating implosions. A similar pinhole imaging experiment (PINEX) diagnostic was recently deployed at the Z facility at Sandia National Laboratories (SNL). Both the SNL and LLNL neutron imagers use similar fiber array scintillators (BCF-99-555). Despite diverse resolution and magnification requirements, both diagnostics put significant onus on the scintillator spatial quality and alignment precision to maintain optimal point spread. Characterization and alignment of the Z-PINEX scintillator and imaging system were done at NSTec/Livermore Operations in 2009, and is currently underway for the NIF Neutron Imager.

The salient features of cavity lights, in particular, mobile luminous objects (MLO's), as have been experimentally observed in superconducting accelerator cavities, are summarized. A model based upon standard electromagnetic interactions between a small particle and the 1.5 GHz cavity excitation field is described. This model can explain some features of these data, in particular, the existence of particle orbits without wall contact. While this result is an important success for the model, it is detailed why the model as it stands is incomplete. It is argued that no avenues for a suitable extension of the model through established physics appear evident, which motivates an investigation of a model based upon a more exotic object, ball lightning. As discussed, further motivation derives from the fact that there are significant similarities in many of the qualitative features of ball lightning and MLO's, even though they appear in quite different circumstances and differ in scale by orders of magnitude. The ball lightning model, which incorporates electromagnetic charges and currents, is based on a symmetrized set of Maxwell's equations in which the electromagnetic sources and fields are characterized by a process called dyality rotation. It is shown that a consistent mathematical description of dyality …

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Several recent reports have identified the scientific requirements for a future soft X-ray light source [1, 2, 3, 4, 5], and a high-repetition-rate free-electron laser (FEL) facility responsive to them is being studied at Lawrence Berkeley National Laboratory (LBNL) [6]. The facility is based on a continuous-wave (CW) superconducting linear accelerator with beam supplied by a high-brightness, high-repetition-rate photocathode electron gun operating in CW mode, and on an array of FELs to which the accelerated beam is distributed, each operating at high repetition rate and with even pulse spacing. Dependent on the experimental requirements, the individualFELs may be configured for either self-amplified spontaneous emission (SASE), seeded highgain harmonic generation (HGHG), echo-enabled harmonic generation (EEHG), or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format ranging from sub-femtoseconds to hundreds of femtoseconds. This new light source would serve a broad community of scientists in many areas of research, similar to existing utilization of storage ring based light sources. To reduce technical risks and constructioncosts, accelerator research, development, and design studies at LBNL target the most critical components and systems of the facility. We are developing a high-repetition-rate low-emittance electron gun, high quantum …

Experimental studies of light emission phenomena in superconducting RF cavities, which we categorize under the general heading of cavity lights, are described. The cavity lights data, which were obtained using a small CCD video camera, were collected in a series of nine experimental runs ranging from {approx} 1/2 to {approx} 2 h in duration. The video data were recorded on a standard VHS tape. As the runs progressed, additional instrumentation was added. For the last three runs a LabVIEW controlled data acquisition system was included. These runs furnish evidence for several, possibly related, light emission phenomena. The most intriguing of these is what appear to be small luminous objects {le} 1.5 mm in size, freely moving about in the vacuum space, generally without wall contact, as verified by reflections of the tracks in the cavity walls. In addition, on a number of occasions, these objects were observed to bounce off of the cavity walls. The wall-bounce aspect of most of these events was clearly confirmed by pre-bounce and post-bounce reflections concurrent with the tracks. In one of the later runs, a mode of behavior was observed that was qualitatively different from anything observed in the earlier runs. Perhaps the most …

This article discusses non-Markovian nonstationary completely positive open-quantum-system dynamics.

Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. These porous nanowires also retain the crystallographic orientation of the wafer from which they are etched. Electron microscopy and diffraction confirm their single-crystallinity and reveal the silicon surrounding the pores is as thin as several nanometers. Confocal fluorescence microscopy showed that the photoluminescence (PL) of these arrays emanate from the nanowires themselves, and their PL spectrum suggests that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices.

Dynamic transmission electron microscopy (DTEM) has the potential to provide insight into nanoparticle catalyst dynamics by obtaining direct images with high spatial and temporal resolution. To date, the limited signal to noise ratios attainable for dispersed nanoparticle samples have made such studies difficult to perform at the highest resolution. These limitations have been overcome by the fabrication of an annular objective lens aperture that permits images to be obtained with a 5 fold increase in the signal to background ratio. This annular dark field imaging mode is shown here to vastly improve the contrast attainable in 15ns pulsed electron images and allows particles as small as 30nm in diameter to be observed.

This report addresses the aluminum solubility and its effect on sodium management.

Single-molecule magnets (SMMs) have been the subject of much interest in recent years because their molecular nature and inherent physical properties allow the crossover between classical and quantum physics to be observed. The macroscopic observation of quantum phenomena - tunneling between different spin states, quantum interference between tunnel paths - not only allows scientists to study quantum mechanical laws in great detail, but also provides model systems with which to investigate the possible implementation of spin-based solid state qubits and molecular spintronics. The isolation of small, simple SMMs is therefore an exciting prospect. To date almost all SMMs have been made via the self-assembly of 3d metal ions in the presence of bridging/chelating organic ligands. However, very recently an exciting new class of SMMs, based on 3d metal clusters (or single lanthanide ions) housed within polyoxometalates, has appeared. These types of molecule, in which the SMM is completely encapsulated within (or shrouded by) a 'protective' organic or inorganic sheath have much potential for design and manipulation: for example, for the removal of unwanted dipolar interactions, the introduction of redox activity, or to simply aid functionalization for surface grafting. Calix[4]arenes are cyclic (typically bowl-shaped) polyphenols that have been used extensively in …