BackgroundIncreasing energy costs and environmental concerns have motivated engineering microbes for the production of ?second generation? biofuels that have better properties than ethanol.Results& ConclusionsSaccharomyces cerevisiae was engineered with an n-butanol biosynthetic pathway, in which isozymes from a number of different organisms (S. cerevisiae, Escherichia coli, Clostridium beijerinckii, and Ralstonia eutropha) were substituted for the Clostridial enzymes and their effect on n-butanol production was compared. By choosing the appropriate isozymes, we were able to improve production of n-butanol ten-fold to 2.5 mg/L. The most productive strains harbored the C. beijerinckii 3-hydroxybutyryl-CoA dehydrogenase, which uses NADH as a co-factor, rather than the R. eutropha isozyme, which uses NADPH, and the acetoacetyl-CoA transferase from S. cerevisiae or E. coli rather than that from R. eutropha. Surprisingly, expression of the genes encoding the butyryl-CoA dehydrogenase from C. beijerinckii (bcd and etfAB) did not improve butanol production significantly as previously reported in E. coli. Using metabolite analysis, we were able to determine which steps in the n-butanol biosynthetic pathway were the most problematic and ripe for future improvement.

Phagocytosis is the central process by which macrophage cellsinternalize and eliminate infectious microbes as well as apoptoticcells. During maturation, phagosomes containing engulfed particlesfuse with various endosomal compartments through theaction of regulatory molecules on the phagosomal membrane. Inthis study, we performed a proteomic analysis of the membranefraction from latex bead-containing (LBC) phagosomes isolatedfrom macrophages. The profile, which comprised 546 proteins,suggests diverse functions of the phagosome and potential connectionsto secretory processes, toll-like receptor signaling, andautophagy. Many identified proteins were not previously knownto reside in the phagosome. We characterized several proteins inLBC phagosomes that change in abundance on induction of autophagy,a process that has been previously implicated in the hostdefense against microbial pathogens. These observations suggestcrosstalk between autophagy and phagocytosis that may be relevantto the innate immune response of macrophages.

Portable, single-sided NMR sensors can operate under conditions inaccessible to conventional NMR while featuring lower cost, portability, and the ability to analyze arbitrary-sized objects. Such sensors can nondestructively probe the interior of samples by collecting images and measuring relaxation and diffusion constants,and, given careful shimming schemes, even perform chemical analysis. The inherently strong magnetic-field gradients of single-sided sensors developed so far has prevented imaging of materials with high water content, such as biological tissues, over large volumes whereas designs with more homogeneous fields suffer from low field strength and typically cannot probe volumes larger than 10 cm3. We present a design with a continuously adjustable sensitive volume, enabling the effective volume to be enlarged several fold. This process allows for imaging in reasonable times of much bigger objects and opens the door to the possibility of clinical imaging with portable sensors. We demonstrate MRI in axial and saggital planes, at different depths of the sensitive volume and T1-weighted contrast in a tissue sample.

Development of advanced hydrogen separation membranes in support of hydrogen production processes such as coal gasification and as front end gas purifiers for fuel cell based system is paramount to the successful implementation of a national hydrogen economy. Current generation metallic hydrogen separation membranes are based on Pd-alloys. Although the technology has proven successful, at issue is the high cost of palladium. Evaluation of non-noble metal based dense metallic separation membranes is currently receiving national and international attention. The focus of the reported work was to develop a scaled reactor with a VNi-Ti alloy membrane to replace a production Pd-alloy tube-type purification/diffuser system.

It is recognized that hydrogen separation membranes are a key component of the emerging hydrogen economy. A potentially exciting material for membrane separations are bulk metallic glass materials due to their low cost, high elastic toughness and resistance to hydrogen 'embrittlement' as compared to crystalline Pd-based membrane systems. However, at elevated temperatures and extended operation times structural changes including partial crystallinity may appear in these amorphous metallic systems. A systematic evaluation of the impact of partial crystallinity/devitrification on the diffusion and solubility behavior in multi-component Metallic Glass materials would provide great insight into the potential of these materials for hydrogen applications. This study will report on the development of time and temperature crystallization mapping and their use for interpretation of 'in-situ' hydrogen permeation at elevated temperatures.

The K East (KE) Basin facilities are located near the north end of the Hanford Site's 100 K area. The facilities were built in 1950 as part of the KE Reactor complex and constructed within 400 meters of the Columbia River, which is the largest river in the Pacific Northwest and by volume the fourth largest river in the United States. The basin, located adjacent to the reactor, was used for the underwater storage of irradiated nuclear fuel discharged from the reactor. The basin was covered by a superstructure comprising steel columns and beams, concrete, and cement asbestos board (CAB) siding. The project's mission was to complete demolition of the structure over the K East basin within six months of tumover from facility deactivation activities. The demolition project team implemented open-air demolition techniques to demolish the facility to slab-on-grade. Several innovative techniques were used to control contamination and maintain contamination control within the confines of the demolition exclusion zone. The techniques, which focused on a defense-in-depth approach, included spraying fixatives on interior and exterior surfaces before demolition began; applying fixatives; misting using a fine spray of water during demolition; and demolishing the facility systematically. Another innovation that aided demolition was …

Fast intermittent transport has been observed in the scrape-off layer (SOL) of major tokamaks including Alcator C-Mod, DIII-D, and NSTX. This kind of transport is not diffusive but rather convective. It strongly increases plasma flux to the chamber walls and enhances the recycling of neutral particles in the main chamber. We discuss anomalous cross-field convection (ACFC) model for impurity and main plasma ions and its relation to intermittent transport events, i.e. plasma density blobs and holes in the SOL. Along with plasma diffusivity coefficients, our transport model introduces time-independent anomalous cross-field convective velocity. In the discharge modelling, diffusivity coefficients and ACFC velocity profiles are adjusted to match a set of representative experimental data. We use this model in the edge plasma physics code UEDGE to simulate the multi-fluid two-dimensional transport for these three tokamaks. We present simulation results suggesting the dominance of anomalous convection in the far SOL transport. These results are consistent with the hypothesis that the chamber wall is an important source of impurities and that different impurity charge states have different directions of anomalous convective velocity.

We present the longitudinal coherence measurement of the transient inversion collisional x-ray laser for the first time. The Ni-like Pd x-ray laser at 14.68 nm is generated by the LLNL COMET laser facility and is operating in the gain-saturated regime. Interference fringes are produced using a Michelson interferometer setup in which a thin multilayer-coated membrane is used as a beam splitter. The longitudinal coherence length for the picosecond duration 4d{sup 1}S{sub 0} {yields} 4p{sup 1}P{sub 1} lasing transition is determined to be {approx}400 {micro}m (1/e HW) by adjusting the length of one interferometer arm and measuring the resultant variation in fringe visibility. This is four times improved coherence than previous measurements on quasi-steady state schemes largely as a result of the narrower line profile in the lower temperature plasma. The inferred gain-narrowed linewidth of {approx}0.29 pm is also substantially narrower than previous measurements on quasi-steady state x-ray laser schemes. This study shows that the coherence of the x-ray laser beam can be improved by changing the laser pumping conditions. The x-ray laser is operating at 4 - 5 times the transform-limited pulse.

The availability of the assembled mouse genome makespossible, for the first time, an alignment and comparison of two largevertebrate genomes. We have investigated different strategies ofalignment for the subsequent analysis of conservation of genomes that areeffective for different quality assemblies. These strategies were appliedto the comparison of the working draft of the human genome with the MouseGenome Sequencing Consortium assembly, as well as other intermediatemouse assemblies. Our methods are fast and the resulting alignmentsexhibit a high degree of sensitivity, covering more than 90 percent ofknown coding exons in the human genome. We have obtained such coveragewhile preserving specificity. With a view towards the end user, we havedeveloped a suite of tools and websites for automatically aligning, andsubsequently browsing and working with whole genome comparisons. Wedescribe the use of these tools to identify conserved non-coding regionsbetween the human and mouse genomes, some of which have not beenidentified by other methods.

We report a two-step growth method to obtain uniformly coalesced epitaxial lateral overgrown a-plane GaN by metal-organic chemical vapor deposition (MOCVD). By obtaining a large wing height to width aspect ratio in the first step followed by enhanced lateral growth in the second step via controlling the growth temperature, we reduced the tilt angle between the advancing Ga-polar and N-polar wings for improved properties. Transmission electron microscopy (TEM) showed that the threading dislocation density in the wing area was 1.0 x 10{sup 8}cm{sup -2}, more than two orders of magnitude lower than that in the window area (4.2 x 10{sup 10} cm{sup -2}). However, a high density of basal stacking faults, 1.2 x 10{sup 4} cm{sup -1}, was still observed in the wing area. Near field scanning optical microscopy (NSOM) at room temperature revealed that the luminescence was mainly from the wing regions with very little contribution from the windows and meeting fronts. These observations suggest that due to significant reduction of threading dislocations radiative recombination is enhanced in the wings.

We utilize ultrafast terahertz pulses to monitor the carrierdynamics in the high-TC superconductor Bi2Sr2CaCu2O8+delta. Thetemperature, density and timedependence distinctly exposes a bimolecularrecombination process of quasiparticles which underlies formation ofCooper pairs.

The heats of vaporization of the room temperature ionic liquids (RTILs) N-butyl-N-methylpyrrolidinium bistrifluorosulfonylimide, N-butyl-N-methylpyrrolidinium dicyanamide, and 1-butyl-3-methylimidazolium dicyanamide are determined using a heated effusive vapor source in conjunction with single photon ionization by a tunable vacuum ultraviolet synchrotron source. The relative gas phase ionic liquid vapor densities in the effusive beam are monitored by clearly distinguished dissociative photoionization processes via a time-of-flight mass spectrometer at a tunable vacuum ultraviolet beamline 9.0.2.3 (Chemical Dynamics Beamline) at the Advanced Light Source synchrotron facility. Resulting in relatively few assumptions, through the analysis of both parent cations and fragment cations, the heat of vaporization of N-butyl-N-methylpyrrolidinium bistrifluorosulfonylimide is determined to be Delta Hvap(298.15 K) = 195+-19 kJ mol-1. The observed heats of vaporization of 1-butyl-3-methylimidazolium dicyanamide (Delta Hvap(298.15 K) = 174+-12 kJ mol-1) and N-butyl-N-methylpyrrolidinium dicyanamide (Delta Hvap(298.15 K) = 171+-12 kJ mol-1) are consistent with reported experimental values using electron impact ionization. The tunable vacuum ultraviolet source has enabled accurate measurement of photoion appearance energies. These appearance energies are in good agreement with MP2 calculations for dissociative photoionization of the ion pair. These experimental heats of vaporization, photoion appearance energies, and ab initio calculations corroborate vaporization of these RTILs as intact cation-anion ion …

The lithium iron phosphate chemistry is plagued by the poor conductivity and slow lithium diffusion in the solid phase. In order to alleviate these problems, various research groups have adopted different strategies including decreasing the particle sizes, increasing the carbon content, and adding dopants. In this study we obtained LiFePO4 electrodes from six different sources and used a combined model-experimental approach to compare the performance. Samples ranged from one with no carbon coating to one with 15 percent coating. In addition, particle sizes varied by as much as a order of magnitude between samples. The study detailed in this manuscript allows us to provide insight into the relative importance of the conductivity of the samples compared to the particle size, the impact of dopant on performance and ideas for making materials in order to maximize the power capability of this chemistry.

Lithium-ion cells, with graphite anodes and LiNi0.8Co0.15Al0.05O2 cathodes, were cycled for up to 1000 cycles over different ranges of SOC and temperatures. The decline in cell performance increases with the span of SOC and temperature during cycling. Capacity fade was caused by a combination of the loss of cycleable Li and degradation of the cathode. The room temperature anodes showed SEI compositions and degrees of graphite disorder that correlated with the extent of the Li consumption, which was linear in cell test time. TEM of the cathodes showed evidence of crystalline defects, though no major new phases were identified, consistent with XRD. No evidence of polymeric deposits on the cathode particles (FTIR) was detected although both Raman and TEM showed evidence of P-containing deposits from electrolyte salt degradation. Raman microscopy showed differences in relative carbon contents of the cycled cathodes, which is blamed for part of the cathode degradation.

A method is proposed for conditioning electron beams via Thomson scattering. The conditioning provides a quadratic correlation between the electron energy deviation and the betatron amplitude of the electrons, which results in enhanced gain in free-electron lasers. Quantum effects imply conditioning must occur at high laser fluence and moderate electron energy. Conditioning of x-ray free-electron lasers should be achievable with present laser technology, leading to significant size and cost reductions of these large-scale facilities.

Abstract: Electron microscope phase images, produced by direct reconstruction of the scattered electron wave from a focal series of high-resolution images, were used to determine the nature of defects formed in GaN:Mg crystals. We studied bulk crystals grown from dilute solutions of atomic nitrogen in liquid gallium at high pressure and thin films grown by the MOCVD method. All the crystals were grown with Ga-polarity. In both types of samples the majority of defects were three dimensional Mg-rich hexagonal pyramids with bases on the (0001) plane and six walls on {l_brace}11{und 2}3{r_brace} planes seen in cross-section as triangulars. Some other defects appear in cross-section as trapezoidal (rectangular) defects as a result of presence of truncated pyramids. Both type of defects have hollow centers. They are decorated by Mg on all six side walls and a base. The GaN which grows inside on the defect walls shows polarity inversion. It is shown that change of polarity starts from the defect tip and propagates to the base, and that the stacking sequence changes from ab in the matrix to bc inside the defect. Exchange of the Ga sublattice with the N sublattice within the defect leads to 0.6 {+-} 0.2{angstrom} displacement between …

The electrochemical properties of LiFePO4 cathodes with different carbon contents were studied to find out the role of carbon as conductive additive. LiFePO4 cathodes containing from 0 percent to 12 percent of conductive additive (carbon black or mixture of carbon black and graphite) were cycled at different C rates. The capacity of LiFePO4 cathode increased, as conductive additive content increased. Carbon increased the utilization of active material and the electrical conductivity of electrode, but decreased volumetric capacity of electrode.

The cycling performance of low-cost LiFePO4-based high-power lithium-ion cells was investigated and the components were analyzed after cycling to determine capacity fade mechanisms. Pouch type LiFePO4/natural graphite cells were assembled and evaluated by constant C/2 cycling, pulse-power and impedance measurements. From post-test electrochemical analysis after cycling, active materials, LiFePO4 and natural graphite, showed no degradation structurally or electrochemically. The main reasons for the capacity fade of cell were lithium inventory loss by side reaction and possible lithium deposition on the anode.

This paper presents the experimental results of the third and final phase of a cookoff model validation effort. In this phase of the work, two generic Heavy Wall Penetrators (HWP) were tested in two heating orientations. Temperature and strain gage data were collected over the entire test period. Predictions for time and temperature of reaction were made prior to release of the live data. Predictions were comparable to the measured values and were highly dependent on the established boundary conditions. Both HWP tests failed at a weld located near the aft closure of the device. More than 90 percent of unreacted explosive was recovered in the end heated experiment and less than 30 percent recovered in the side heated test.

The finite element method has been routinely used to calculate the image stresses of dislocation segments. When these segments intersect with surfaces, the image stresses at the surfaces diverges singularly. At the presence of these singularities, both convergence and accuracy of using the finite element method need to be examined critically. This article addresses these issues with the aim toward the application of dislocation dynamics simulations in thin films.

We present the first measurements of the absolute albedos of hohlraums made from gold or from high-Z mixtures. The measurements are performed over the range of radiation temperatures (70-100 eV) expected during the foot of an indirect-drive temporally-shaped ignition laser pulse, where accurate knowledge of the wall albedo (i.e. soft x-ray wall re-emission) is most critical for determining capsule radiation symmetry. We find that the gold albedo agrees well with calculations using the super transition array opacity model, potentially providing additional margin for ICF ignition.

The utilization of sol-gel chemical methodology to prepare nanostructured energetic materials as well as the concepts of nanoenergetics is described. The preparation and characterization of two totally different compositions is detailed. In one example, nanostructured aerogel and xerogel composites of sol-gel iron (III) oxide and ultra fine grained aluminum (UFG Al) are prepared, characterized, and compared to a conventional micron-sized Fe{sub 2}O{sub 3}/Al thermite. The exquisite degree of mixing and intimate nanostructuring of this material is illustrated using transmission and scanning electron microscopies (TEM and SEM). The nanocomposite material has markedly different energy release (burn rate) and thermal properties compared to the conventional composite, results of which will be discussed. Small-scale safety characterization was performed aerogels and xerogels of the nanostructured thermite. The second nanostructured energetic material consists of a nanostructured hydrocarbon resin fuel network with fine ammonium perchlorate (NH{sub 4}ClO{sub 4}) oxidizer present.

New emissions regulations will increase the need for compact, inexpensive sensors for monitoring and control of automotive exhaust gas pollutants. Species of interest include hydrocarbons, carbon monoxide, and oxides of nitrogen (NO{sub x}). The current work is directed towards the development of fast, high sensitivity electrochemical NO{sub x} sensors for automotive diesel applications. We have investigated potentiometric NO sensors with good sensitivity and fast response when operated in 10% O{sub 2}. The sensors consist of yttria-stabilized zirconia substrates attached with NiCr{sub 2}O{sub 4} sensing electrodes and Pt reference electrodes. A composite NiCr{sub 2}O{sub 4}:Rh sensing electrode is shown to give significantly faster response than NiCr{sub 2}O{sub 4} alone. The exact role of the Rh in enhancing the response speed is not clear at present. However, the Rh appears to accumulate at the contacts between the NiCr{sub 2}O{sub 4} particles and may enhance the inter-particle electronic conduction. Ongoing testing of these sensors is being performed to elucidate the sensing mechanisms and to quantify cross sensitivity to, for example, NO{sub 2}.

Compact soft x-ray laser sources are now used routinely for various applications primarily because of their high repetition rate, high photon fluence and short pulse duration characteristics. For some of these applications, for example interferometry of high density laser-produced plasmas, longer optical drive pulses, 6-13 ps (FWHM), have been implemented to maximize the x-ray output and coherence. It is therefore important to know the x-ray laser pulse length, shape and repeatability for these specific experiments as a baseline measurement but also to better understand the temporal behavior as a function of the pumping conditions in general. We report a detailed temporal characterization of the picosecond-driven 14.7 nm Ni-like Pd ion x-ray laser on the Compact Multipulse Terawatt (COMET) laser at LLNL using an ultrafast x-ray streak camera measurement of a horizontal slice of the near-field x-ray laser pattern. This is measured as a function of the chirped pulse amplification pumping laser conditions, including varying the pump pulse from 0.5-27 ps (FWHM), varying the plasma column length as well as investigating traveling wave (TW) and non-TW irradiation conditions.