Cryo electron tomography (cryo-ET) is the primary method for obtaining 3D reconstructions of intact bacteria, viruses, and complex molecular machines ([7],[2]). It first flash freezes a specimen in a thin layer of ice, and then rotates the ice sheet in a transmission electron microscope (TEM) recording images of different projections through the sample. The resulting images are aligned and then back projected to form the desired 3-D model. The typical resolution of biological electron microscope is on the order of 1 nm per pixel which means that small imprecision in the microscope's stage or lenses can cause large alignment errors. To enable a high precision alignment, biologists add a small number of spherical gold beads to the sample before it is frozen. These beads generate high contrast dots in the image that can be tracked across projections. Each gold bead can be seen as a marker with a fixed location in 3D, which provides the reference points to bring all the images to a common frame as in the classical structure from motion problem. A high accuracy alignment is critical to obtain a high resolution tomogram (usually on the order of 5-15nm resolution). While some methods try to automate the …

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Photochemical conversion of CO{sub 2} to fuels or useful chemicals using renewable solar energy is an attractive solution to both the world's need for fuels and the reduction of greenhouse gases. Rhenium(I) and ruthenium(II) diimine complexes have been shown to act as photocatalysts and/or electrocatalysts for CO{sub 2} reduction to CO. We have studied these photochemical systems focusing on the identification of intermediates and the bond formation/cleavage reactions between the metal center and CO{sub 2}. For example, we have produced the one-electron-reduced monomer (i.e. Re(dmb)(CO){sub 3}S where dmb = 4,4'-dimethy-2,2'-bipyridine and S = solvent) either by reductive quenching of the excited states of fac-[Re(dmb)(CO){sub 3}(CH{sub 3}CN)]PF{sub 6} or by photo-induced homolysis of [Re(dmb)(CO){sub 3}]{sub 2}. We previously found that: (1) the remarkably slow dimerization of Re(dmb)(CO){sub 3}S is due to the absence of a vacant coordination site for Re-Re bond formation, and the extra electron is located on the dmb ligand; (2) the reaction of Re(dmb)(CO){sub 3}S with CO{sub 2} forms a CO{sub 2}-bridged binuclear species (CO){sub 3}(dmb)Re-CO(O)-Re(dmb)(CO){sub 3} as an intermediate in CO formation; and (3) the kinetics and mechanism of reactions are consistent with the interaction of the CO{sub 2}-bridged binuclear species with CO{sub 2} to form CO …

The response of exponentially growing Desulfovibrio vulgarisHildenborough to pH 10 stress was studied using oligonucleotidemicroarrays and a study set of mutants with genes suggested by microarraydata to be involved in the alkaline stress response deleted. The datashowed that the response of D. vulgaris to increased pH is generallysimilar to that of Escherichia coli but is apparently controlled byunique regulatory circuits since the alternative sigma factors (sigma Sand sigma E) contributing to this stress response in E. coli appear to beabsent in D. vulgaris. Genes previously reported to be up-regulated in E.coli were up-regulated in D. vulgaris; these genes included three ATPasegenes and a tryptophan synthase gene. Transcription of chaperone andprotease genes (encoding ATP-dependent Clp and La proteases and DnaK) wasalso elevated in D. vulgaris. As in E. coli, genes involved in flagellumsynthesis were down-regulated. The transcriptional data also identifiedregulators, distinct from sigma S and sigma E, that are likely part of aD. vulgaris Hildenborough-specific stress response system.Characterization of a study set of mutants with genes implicated inalkaline stress response deleted confirmed that there was protectiveinvolvement of the sodium/proton antiporter NhaC-2, tryptophanase A, andtwo putative regulators/histidine kinases (DVU0331 andDVU2580).

The present study demonstrates that [Ru{sup II}(NH{sub 3})(q)(trpy)]{sup +} has an ability to oxidize alcohols catalytically under very mild conditions under electrolysis at +0.35 V in MeOH. The elucidation of the reaction mechanisms in the alcohol-oxidation is underway.

National Security Technologies, LLC (NSTec), has established a work management program and corresponding electronic Facilities and Operations Management Information System (e-FOM) to implement Integrated Safety Management (ISM). The management of work scopes, the identification of hazards, and the establishment of implementing controls are reviewed and approved through electronic signatures. Through the execution of the program and the implementation of the electronic system, NSTec staff work within controls and utilize feedback and improvement process. The Integrated Work Control Manual further implements the five functions of ISM at the Activity level. By adding the Risk and Work Configuration Management program, NSTec establishes risk acceptance (business and physical) for liabilities within the performance direction and work management processes. Requirements, roles, and responsibilities are specifically identified in the program while e-FOM provides the interface and establishes the flowdown from the Safety Chain to work and facilities management processes to company work-related directives, and finally to Subject Matter Expert concurrence. The Program establishes, within the defined management structure, management levels for risk identification, risk mitigation (controls), and risk acceptance (business and physical) within the Safety Chain of Responsibility. The Program also implements Integrated Safeguards and Security Management within the NSTec Safety Chain of Responsibility. Once …

Demand response (DR) is an effective tool which resolves inconsistencies between electric power supply and demand. It further provides a reliable and credible resource that ensures stable and economical operation of the power grid. This paper introduces systematic definitions for DR and demand side management, along with operational differences between these two methods. A classification is provided for DR programs, and various DR strategies are provided for application in air conditioning and refrigerating systems. The reliability of DR is demonstrated through discussion of successful overseas examples. Finally, suggestions as to the implementation of demand response in China are provided.

Ionic liquids (ILs) are a rapidly expanding family of condensed-phase media with important applications in energy production, nuclear fuel and waste processing, improving the efficiency and safety of industrial chemical processes, and pollution prevention. ILs are generally nonvolatile, noncombustible, highly conductive, recyclable and capable of dissolving a wide variety of materials. They are finding new uses in chemical synthesis, catalysis, separations chemistry, electrochemistry and other areas. Ionic liquids have dramatically different properties compared to conventional molecular solvents, and they provide a new and unusual environment to test our theoretical understanding of charge transfer and other reactions. We are interested in how IL properties influence physical and dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions. Successful use of ionic liquids in radiation-filled environments, where their safety advantages could be significant, requires an understanding of ionic liquid radiation chemistry. For example, characterizing the primary steps of IL radiolysis will reveal radiolytic degradation pathways and suggest ways to prevent them or mitigate their effects on the properties of the material. An understanding of ionic liquid radiation chemistry will also facilitate pulse radiolysis studies of general chemical reactivity in ILs, …

Strontium sorption to amorphous silica and goethite was measured as a function of pH and dissolved strontium and carbonate concentrations at 25 C. Strontium sorption gradually increases from 0 to 100% from pH 6 to 10 for both phases and requires multiple outer-sphere surface complexes to fit the data. All data are modeled using the triple layer model and the site-occupancy standard state; unless stated otherwise all strontium complexes are mononuclear. Strontium sorption to amorphous silica in the presence and absence of dissolved carbonate can be fit with tetradentate Sr{sup 2+} and SrOH{sup +} complexes on the {beta}-plane and a monodentate Sr{sup 2+} complex on the diffuse plane to account for strontium sorption at low ionic strength. Strontium sorption to goethite in the absence of dissolved carbonate can be fit with monodentate and tetradentate SrOH{sup +} complexes and a tetradentate binuclear Sr{sup 2+} species on the {beta}-plane. The binuclear complex is needed to account for enhanced sorption at high strontium surface loadings. In the presence of dissolved carbonate additional monodentate Sr{sup 2+} and SrOH{sup +} carbonate surface complexes on the {beta}-plane are needed to fit strontium sorption to goethite. Modeling strontium sorption as outer-sphere complexes is consistent with quantitative analysis …

The pairing of a Lindqvist or Keggin polyoxometalate (POM) anion with an appropriate tetraalkylphosphonium cation, [R{sub 3}R{prime}P]{sup +}, has been shown to yield an original family of ionic liquids (POM-ILs), among them salts liquid at or near ambient temperature. The physicochemical properties of several such 'inorganic liquids', in particular their thermal properties, suggests the possible application of these compounds as robust, thermally-stable solvents for liquid-liquid extraction. A preliminary evaluation of the potential of POM-ILs in this application is presented.

Photomultiplier-based scintillator spectrometers are the systems of choice for a multitude of X-ray and gamma radiation measurement applications. Despite widespread use, they have numerous shortcomings. The most serious is the relatively poor energy resolution that makes isotope identification problematic particularly in the case of trace quantities. Energy resolution in scintillator/photomultiplier tube (PMT) spectrometers is governed by a combination of the crystal intrinsic resolution that includes non-linearity effects, photomultiplier statistics, and the variability in the probability of a scintillation photon generating a photoelectron at the photocathode. It is evident that energy resolution in these systems is linked to both the physics of light generation in the scintillator, as well as the characteristics of the PMT. PMTs also present design problems especially in the case of handheld and portable instruments due to their considerable weight and volume. Additionally, PMTs require well-regulated high voltage and are vulnerable to magnetic fields.

The study of the transport of electrons, and the flow of energy into a solid target or dense plasma, is instrumental in the development of fast ignition inertial confinement fusion. An extreme ultraviolet (XUV) imaging diagnostic at 256 eV and 68 eV provides information about heating and energy deposition within petawatt laser-irradiated targets. XUV images of several irradiated solid targets are presented.

Production-cost models for high-power laser-diodes indicate systems of 10GW peak power coupled with facilitization of semi-conductor manufacturing capacity could yield costs below $0.02/Watt. This is sufficient to make IFE competitive with other nuclear power technologies.

We present new observations of Jupiter's ring system at a wavelength of 2.2 {micro}m obtained with the 10-m W. M. Keck telescopes on three nights during a ring plane crossing: UT 19 December 2002, and 22 and 26 January 2003. We used conventional imaging, plus adaptive optics on the last night. Here we present detailed radial profiles of the main ring, halo and gossamer rings, and interpret the data together with information extracted from radio observations of Jupiter's synchrotron radiation. The main ring is confined to a 800-km-wide annulus between 128,200 and 129,000 km, with a {approx} 5000 km extension on the inside. The normal optical depth is 8 x 10{sup -6}, 15% of which is provided by bodies with radii a {approx}> 5 cm. These bodies are as red as Metis. Half the optical depth, {tau} {approx} 4 x 10{sup -6}, is attributed to micron-sized dust, and the remaining {tau} {approx} 3 x 10{sup -6} to grains tens to hundreds of {micro}m in size. The inward extension consists of micron-sized (a {approx}< 10 {micro}m) dust, which probably migrates inward under Poynting-Robertson drag. The inner limit of this extension falls near the 3:2 Lorentz resonance (at orbital radius r = …

The Savannah River Site (SRS), a Department of Energy (DOE) facility, has over 30 million gallons of legacy waste from its many years of processing nuclear materials. The majority of waste is stored in 49 buried tanks. Available underground piping is the primary and desired pathway to transfer waste from one tank to another until the waste is delivered to the glass plant, DWPF, or the grout plant, Saltstone. Prior to moving the material, the tank contents need to be evaluated to ensure the correct destination for the waste is chosen. Access ports are available in each tank top in a number of locations and sizes to be used to obtain samples of the waste for analysis. Material consistencies vary for each tank with the majority of waste to be processed being radioactive salts and sludge. The following paper describes the progression of equipment and techniques developed to obtain core samples of salt and solid sludge at SRS.

The 200-ZP-1 Groundwater Operable Unit (OU) is one of two groundwater OUs located within the 200 West groundwater aggregate area of the Hanford Site. The primary risk-driving contaminants within the 200-ZP-1 OU include carbon tetrachloride and technetium-99 (Tc-99). A pump-and-treat system for this OU was initially installed in 1995 to control the 0.002 kg/m{sup 3} (2000 {micro}g/L) contour of the carbon tetrachloride plume. Carbon tetrachloride is removed from groundwater with the assistance of an air-stripping tower. Ten extraction wells and three injection wells operate at a combined rate of approximately 0.017m{sup 3}/s (17.03 L/s). In 2005, groundwater from two of the extraction wells (299-W15-765 and 299-W15-44) began to show concentrations greater than twice the maximum contaminant level (MCL) of Tc-99 (33,309 beq/m{sup 3} or 900 pCi/L). The Tc-99 groundwater concentrations from all ten of the extraction wells when mixed were more than one-half of the MCL and were slowly increasing. If concentrations continued to rise and the water remained untreated for Tc-99, there was concern that the water re-injected into the aquifer could exceed the MCL standard. Multiple treatment technologies were reviewed for selectively removing Tc-99 from the groundwater. Of the treatment technologies, only ion exchange was determined to be …

A treatability test plan has been prepared to address options for remediating portions of the deep vadose zone beneath a portion of the U.S. Department of Energy's (DOE's) Hanford Site. The vadose zone is the region of the subsurface that extends from the ground surface to the water table. The overriding objective of the treatability test plan is to recommend specific remediation technologies and laboratory and field tests to support the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 and Resource Conservation and Recovery Act of 1976 remedial decision-making process in the Central Plateau of the Hanford Site. Most of the technologies considered involve removing water from the vadose zone or immobilizing the contaminants to reduce the risk of contaminating groundwater. A multi-element approach to initial treatability testing is recommended, with the goal of providing the information needed to evaluate candidate technologies. The proposed tests focus on mitigating two contaminants--uranium and technetium. Specific technologies are recommended for testing at areas that may affect groundwater in the future, but a strategy to test other technologies is also presented.

Morphology- and layer-dependent electronic structure and dynamics at the PTCDA/Ag(111) interface have been studied with angle-resolved two-photon photoemission. In Stranski-Krastanov growth modes, the exposed wetting layer inhibited the evolution of the vacuum level and valence band to bulk values. For layer-by-layer growth, we observed the transition of electron structure from monolayer to bulk values within eight monolayers. Effective masses and lifetimes of the conduction band and the n=1 image potential state were measured to be larger for disordered layers. The effective mass was interpreted in the context of charge mobility measurements.

Recent multi-wavelength observations of 3C454.3, in particular during its giant outburst in 2005, put severe constraints on the location of the 'blazar zone', its dissipative nature, and high energy radiation mechanisms. As the optical, X-ray, and millimeter light-curves indicate, significant fraction of the jet energy must be released in the vicinity of the millimeter-photosphere, i.e. at distances where, due to the lateral expansion, the jet becomes transparent at millimeter wavelengths. We conclude that this region is located at {approx} 10 parsecs, the distance coinciding with the location of the hot dust region. This location is consistent with the high amplitude variations observed on {approx} 10 day time scale, provided the Lorentz factor of a jet is {Gamma}{sub j} {approx} 20. We argue that dissipation is driven by reconfinement shock and demonstrate that X-rays and {gamma}-rays are likely to be produced via inverse Compton scattering of near/mid IR photons emitted by the hot dust. We also infer that the largest gamma-to-synchrotron luminosity ratio ever recorded in this object - having taken place during its lowest luminosity states - can be simply due to weaker magnetic fields carried by a less powerful jet.

A series of bunch length measurements were made in SPEAR3 for two different machine optics. In the achromatic optics the bunch length increases from the low-current value of 16.6ps rms to about 30ps at 25ma/bunch yielding an inductive impedance of -0.17{Omega}. Reducing the momentum compaction factor by a factor of {approx}60 [1] yields a low-current bunch length of {approx}4ps rms. In this paper we review the experimental setup and results.

A complete series of LiNi0.4Co0.2-yAlyMn0.4O2 (0<_y<_0.2) materials have been synthesized and investigated as cathode materials for lithium ion batteries. When cycled between 2.0 and 4.3 V vs. Li/Li+ at a current density of 0.1 mA/cm2, stable capacities of ~;;160 mAh/g for y=0 to ~;;110 mAh/g for y=0.2 are achieved. Upon increasing the current density, it is found that all materials containing aluminum show reduced polarization and improved rate performance. The optimal performance at all current densities was found for the compound with y=0.05. The effect of aluminumsubstitution on the crystal structure of the host is discussed.

The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) project presently under construction at SLAC. The injector section, from drive laser and RF photocathode gun through first bunch compressor chicane, was installed in fall 2006. Initial system commissioning with an electron beam was completed in August 2007, with the goal of a 1.2-micron emittance in a 1-nC bunch clearly demonstrated. The second phase of commissioning, including second bunch compressor and full linac, is planned for 2008, with FEL commissioning in 2009. We report experimental results and experience gained in the first phase of commissioning, including the photo-cathode drive laser, RF gun, photocathode, S-band and X-band RF systems, first bunch compressor, and the various beam diagnostics.

Resonance enhancement of the quantum efficiency of new polarized electron photocathodes based on a short-period strained superlattice structures is reported. The superlattice is a part of an integrated Fabry-Perot optical cavity. We demonstrate that the Fabry-Perot resonator enhances the quantum efficiency by the order of magnitude in the wavelength region of the main polarization maximum. The high structural quality implied by these results points to the very promising application of these photocathodes for spin-polarized electron sources.

Two Monte Carlo systems, EGSnrc and Geant4, were used to calculate dose distributions in large electron fields used in radiotherapy. Source and geometry parameters were adjusted to match calculated results with measurement. Both codes were capable of accurately reproducing the measured dose distributions of the 6 electron beams available on the accelerator. Depth penetration was matched to 0.1 cm. Depth dose curves generally agreed to 2% in the build-up region, although there is an additional 2-3% experimental uncertainty in this region. Dose profiles matched to 2% at the depth of maximum dose in the central region of the beam, out to the point of the profile where the dose begins to fall rapidly. A 3%/3mm match was obtained outside the central region except for the 6 MeV beam, where dose differences reached 5%. The discrepancy observed in the bremsstrahlung tail in published results that used EGS4 is no longer evident. The different systems required different source energies, incident beam angles, thicknesses of the exit window and primary foils, and distance between the primary and secondary foil. These results underscore the requirement for an experimental benchmark of electron scatter for beam energies and foils relevant to radiotherapy.