Article describes how processes including hot compression, cold compression and subsequent annealing on the structures and properties are investigated and compared. They found that applying pressure up to 10 GPa at the glass transition temperature led to permanent densifications and a dramatic increase of elastic moduli by 90%, while thermal annealing reversed the increase and applying pressure at ambient temperature did not increase the modulus.

This article presents a new type of bimodal contrast agent that is based on the self-quenching of indocyanine green (ICG) encapsulated in a biocompatible and biodegradable polymer shell.

This article proposes a three-dimensional (3D) vegetation extraction workflow to extract urban grasses and trees at individual tree level in urban areas using airborne LiDAR and hyperspectral data. Results suggest that two- and three-dimensional urban vegetation extraction could play a significant role in spatial layout optimization and scientific management of urban vegetation.

Article describes study examining 182 alpha-theta session graphs from 10 subject case files for interactions between frequency band activity and subject reports of imagery or biographical memories during crossovers, as well as treatment outcomes.

This article argues against the treatment of Attention deficit/hyperactivity disorder (ADHD) with stimulant medication and behavior therapy, which are also typically reimbursed by healthcare insurers. Evidence suggests that these treatments fail to result in sustained benefit for the vast majority of children who receive them as demonstrated in the NIMH-funded MTA Cooperative study, the gold standard study in ADHD treatment effectiveness research. The authors instead look at the use of neurofeedback which is uniquely suited to treat the neuronal dysregulation that is common in people diagnosed with ADHD. However, healthcare insurers do not regularly cover this treatment method, so the authors direct readers to resources to appeal insurers' denial of coverage for neurofeedback.

In this paper we will describe the synthesis of several amino- and nitro-substituted heterocycles, examples from a continuing research project targeted at the synthesis of new, insensitive energetic materials that possess at least 80% the power of HMX (28% more power than TATB). Recently we reported the synthesis and scale-up of the insensitive energetic material, 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105). The energy content (81% the power of HMX) and thermal stability of LLM-105 make it a viable candidate material for insensitive boosters and deep oil perforation. We will report on recent synthetic improvements and several performance and safety tests performed on LLM-105, including a 1 in. cylinder shot and plate dent. We will also report on the synthesis and characterization of 4-amino-3,5-dinitropyrazole (LLM-116), an interesting new insensitive energetic material with a measured crystal density of 1.90 g/cc, to our knowledge the highest density yet measured for a five-membered heterocycle containing amino- and nitro-substituents. LLM-116 was synthesized by reacting 3,5-dinitropyrazole with 1,1,1-trimethylhydrazinium iodide (TMHI) in DMSO in the presence of base. The synthesis and characterization of 4-amino-5-nitro-1,2,3-triazole (ANTZ) and 43-dinitro-1,2,3-triazole (DNTZ), first described by Baryshnikov and coworkers, will also be presented along with the synthesis of several new energetic materials derived from ANTZ and …

MSO is a good alternative to incineration for the treatment of a variety of organic wastes including obsolete explosives, low-level mixed waste streams, PCB contaminated oils, spent resins and carbon. The Lawrence Livermore National Laboratory (LLNL) has demonstrated the MSO process for the effective destruction of explosives, explosives-contaminated materials, and other wastes on a 1.5 kg/hr bench-scale unit and in an integrated MSO facility capable of treating 8 kg/hr of low-level radioactive mixed wastes. LLNL, under the direction and support of the Joint Demilitarization Technology (JDT) program, is currently building an integrated MSO plant for destroying explosives, explosives-contaminated sludge and explosives-contaminated activated charcoal. In a parallel effort, LLNL also provides technical support to DOE for the implementation of the MSO technology at industrial scale at Richland, Washington. Over 30 waste streams have been demonstrated with LLNL-built MSO systems. In this paper we will present our latest experimental data, our operational experience with MSO and also discuss its process capabilities.

Silica-filled polydimethylsiloxane (PDMS) composite systems find a broad range of applications due to their chemical and environmental resilience and the ability to fine tune, through chemical and processing modifications, the chemical and mechanical properties resulting in a precise engineering property for the final component. Thus, requirements for, and life-performance predictions of, these materials require an understanding of the interaction between the silica filler and the polymer network. Because silica surfaces are well known to have a high affinity for water adsorption, and this water is a critical part of the interface between the silica particles and the polymer matrix, water at this interface has important consequences on the nature of the silica-polymer bonding and subsequently the mechanical behaviour. Previous studies have reported on the water speciation and long-term outgassing kinetics of common fumed and precipitated silicas used in silicone elastomers, and of one such copolymer system in particular. Several different water species were observed to be present with a range of desorption activation energies. The amount and type of species present were observed to be dependent on the thermal and chemical history of the filler and the composite. Solid state Nuclear Magnetic Resonance (NMR) methods based on quantification of residual …

Hardware performance counters are CPU registers that count data loads and stores, cache misses, and other events. Counter data can help programmers understand software performance. Although CPUs typically have multiple counters, each can monitor only one type of event at a time, and some counters can monitor only certain events. Therefore, some CPUs cannot concurrently monitor interesting combinations of events. Software multiplexing partly overcomes this limitation by using time sharing to monitor multiple events on one counter. However, counter multiplexing is harder to implement for multithreaded programs than for single-threaded ones because of certain difficulties in managing the length of the time slices. This paper describes a software library called MPX that overcomes these difficulties. MPX allows applications to gather hardware counter data concurrently for any combination of countable events. MPX data are typically within a few percent of counts recorded without multiplexing.

It is shown that high rate extrusion is a viable production process for obtaining desirable microstructures and mechanical properties in ultrahigh carbon steels (UHCSs). The coefficient of friction for extrusion was determined for the UHCSs as well as five other materials and shown to be a function of stress--decreasing with increasing stress. The extruded UHCSs deform by a diffusion-controlled dislocation creep process. Stacking fault energies have been calculated from the extrusion data and observed to decrease with increasing concentrations of silicon, aluminum and chromium. Microstructures are either ultrafine pearlite when extruded above the eutectoid temperature or ultrafine spheroidite when extruded below the eutectoid temperature. The resulting strength--ductility properties are shown to be superior to those obtained in high-strength low alloy steels.

Microstructural characterization of soft-captured fragments of explosive-driven AerMet 100 alloy hollow cylinders is performed to understand dynamic deformation and localization phenomena. Examination of the fragments reveals the deformation is characterized by bands of localized shear strain and cracking. Fracture surface morphologies for the cylinders are ductile dimples, indicative of tensile or shear failure. Although both annealed and maraged AerMet 100 exhibit similar phenomenon, the width of the shear band in the annealed material is wider than in the maraged material, suggesting the former is more resistant to shear banding.

A new modeling system has been developed to provide a non-meteorologist with tools to predict air pollution transport in regions of complex terrain. This system couples the Penn State/NCAR Mesoscale Model 5 (MM5) with Earth Tech’s CALMET-CALPUFF system using a unique Graphical User Interface (GUI) developed at Pacific Northwest National Laboratory. This system is most useful in data-sparse regions, where there are limited observations to initialize the CALMET model. The user is able to define the domain of interest, provide details about the source term, and enter a surface weather observation through the GUI. The system then generates initial conditions and time constant boundary conditions for use by MM5. MM5 is run and the results are piped to CALPUFF for the dispersion calculations. Contour plots of pollutant concentration are prepared for the user. The primary advantages of the system are the streamlined application of MM5 and CALMET, limited data requirements, and the ability to run the coupled system on a desktop or laptop computer. In comparison with data collected as part of a field campaign, the new modeling system shows promise that a full-physics mesoscale model can be used in an applied modeling system to effectively simulate locally thermally-driven winds …

Propagating filaments of enhanced plasma density, or blobs, observed in 3D numerical simulations of a diverted, neutral-fueled tokamak are studied. Fluctuations of vorticity, electrical potential {phi}, temperature T{sub e} and current density J{sub {parallel}} associated with the blobs have a dipole structure perpendicular to the magnetic field and propagate radially with large E {center_dot} B drift velocities (> 1 km/s). The simulation results are consistent with a 3D blob dynamics model that incorporates increased parallel plasma resistivity (from neutral cooling of the X-point region), blob disconnection from the divertor sheath, X-point closure of the current loops, and collisional physics to sustain the {phi}, T{sub e}, J{sub {parallel}} dipoles.

We report combined Raman, infrared (IR) and x-ray diffraction (XRD) measurements, along with ab initio calculations on formic acid under pressure up to 50 GPa. Contrary to the report of Allan and Clark (PRL 82, 3464 (1999)), we find an infinite chain low-temperature Pna2{sub 1} structure consisting of trans molecules to be a high-pressure phase at room temperature. Our data indicate the symmetrization and a partially covalent character of the intra-chain hydrogen bonds above approximately 20 GPa. Raman spectra and XRD patterns indicate a loss of the long-range order at pressures above 40 GPa with a large hysteresis at decompression. We attribute this behavior to a three-dimensional polymerization of formic acid.

We present two indirect drive inertial fusion targets driven by heavy ions beams for fusion energy production. Because there are uncertainties in the ion beam focal spot size and uncertainties in the accelerator cost, we have tried to design targets that cover a large parameter space. One of the designs requires small ion beam focal spots but produces more than adequate gain at low driver energy (gain 130 from 3.3 MJ of beam energy). The other design allows a large beam spot, but requires more driver energy (gain 55 from 6.7 MJ of beam energy). Target physics issues as well as the implications for the accelerator from each design are discussed.

Targets designed for fast ignition must have clear access for the ignitor laser to the compressed core. This is provided in current concepts by embedding a reentrant cone in the shell, the tip of the cone close to the center of the shell. We have designed a gas-tight direct-drive FI target as the first step in developing a FI ignition target, and have studied its implosion dynamics at Omega with back-lit and self-emission framing cameras. A step in the cone surface, and Al on the shell was required to make the assembly gas-tight; these assemblies withstood >10 atm and had a typical pressure half-life of 2-6 hrs. The implosion of these targets was substantially different from that of previous indirect drive targets; there was much less vaporization of the Au cone, much clearer structure in the collapsing shells, and a possibility that the hot core could escape around the cone rather than punch in its tip. Additionally self-emission images show the heating of the core gas, and its effect on the cone tip. These results will be compared to simulations.

The explosive TATB is used in the Department of Energy's main charges and boosters, where its extraordinary insensitivity to impact, spark and heat make it highly advantageous. This IHE is also used in booster applications in naval weapons, and is being tested as a main charge fill for hard target penetrator projectiles. (Slides 2-5) In order to meet demand, a continuing supply of TATB will be required. However, no production base exists in the U.S. for TATB production, and processes once used to make TATB are relatively expensive, complicated, and considered environmentally hazardous (Slide 6). The primary objective of this project is to reestablish the industrial base for TATB production, using LLNL's new Vicarious Nucleophilic Substitution (VNS) methodology. A secondary objective is to enable a reduction in the cost of TATB production, thus making this explosive attractive to U.S. Department of Defense and commercial customers. This presentation will update information presented at the 1998 NDIA IM & EM meeting held in San Diego, California.

The NanoSIMS 50 represents the state -of-the-art for in situ microanalysis for secondary ion mass spectrometry (SIMS), combining unprecedented spatial resolution (as good as 50 nm) with ultra-high sensitivity (MDL of 200 atoms). The NanoSIMS incorporates an array of detectors, enabling simultaneous collection of 5 elements or isotopes originating from the same sputtered volume of a sample. The primary ion beam (Cs{sup +} or O{sup -}) can be scanned across the sample to produce quantitative secondary ion images. This capability for multiple isotope imaging with high spatial resolution is unique to the NanoSIMS and provides a novel new approach to the study of the distribution of elements in biological materials. We have applied this technique extensively to mammalian cells and bacterial spores. Results from these studies and critical analytical issues such as sample preparation, instrument tuning, and data processing will be discussed.

We present an improved analytical expression for the x-ray dynamic structure factor from a dense plasma which includes the effects of weakly bound electrons. This result can be applied to describe scattering from low to moderate Z plasmas, and it covers the entire range of plasma conditions that can be found in inertial confinement fusion experiments, from ideal to degenerate up to moderately coupled systems. We use our theory to interpret x-ray scattering experiments from solid density carbon plasma and to extract accurate measurements of electron temperature, electron density and charge state. We use our experimental results to validate various equation-of-state models for carbon plasmas.

X-ray sources in the 3-7 keV energy regime can be produced by laser-irradiating mid- and high-Z gas-filled targets with high-powered lasers. A series of experiments have been performed using underdense targets that are supersonically heated with {approx} 35 kJ of 0.35 {micro}m laser light. These targets were cylindrical Be enclosures that were filled with 1-2 atms of Xe or Ar gas. L-shell x-ray emission is emitted from the plasma and detected by Bragg crystal spectrometers and x-ray diodes. Absolute flux measurements show conversion efficiencies of {approx} 10% in the multi-kilovolt x-ray emission. These sources can be used as bright x-ray backlighters or for material testing.

Low rank coals (lignite and subbituminous) contain exchangeable cations. A sample of {minus}20+200 mesh Argonne Premium Wyodak coal was washed with nitric acid in a burette fitted with a coarse glass frit at the base of the graduations to remove the exchangeable cations from the system. The eluent was passed to a flow-through pH electrode and a titration curve was obtained on a computer file. A series of electrodes (pH, calcium, sodium and potassium) were used in separate experiments to follow the elution from the coal. Some implications for coal structure are also indicated.

The serious environmental problems of the South Urals Region of Russia have been broadly described in a report coauthored by Russian weapons scientists. The importance of taking the first steps to prevent further environmental damage and adverse public health effects has been recognized by the international scientific community. Scientists at the Lawrence Livermore National Laboratory have initiated a project to assist the Russians in their pollution prevention efforts. The specific objectives of this project are to: (1) conduct a pragmatic survey of the industrial and governmental pollution sources in a limited geographic region of the South Urals and (2) identify the priorities for pollution prevention and for food and water supply improvements at distribution points. The emphasis is on preventing adverse impacts to human health and improving industrial productivity. This project focuses on immediate pollution problems resulting from current operations and their solutions, not on long-term research related to the large-scale cleanup of legacy wastes. The project emphasizes near-term cost effective solutions to prevent pollution while longer term research aimed at contamination from past practices is pursued by other scientists. The project is being conducted in collaboration with environmental and physical scientists from institutes associated with the Ural Branch of …

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A 1200 channel Si(Li) detector system has been developed for transvenous coronary angiography experiments using synchrotron radiation. It is part of the synchrotron medical imaging facility at the National Synchrotron Light Source. The detector is made from a single crystal of lithium-drifted silicon with an active area 150 mm long {times} 11 mm high {times} 5 mm thick. The elements are arranged in two parallel rows of 600 elements with a center-to-center spacing of 0.25 mm. All 1200 elements are read out simultaneously every 4 ms. A Intel 80486 based computer with a high speed digital signal processing interface is used to control the beamline hardware and to acquire a series of images. The signal-to-noise, linearity and resolution of the system have been measured. Human images have been taken with this system.