Speedup, a commercial software package for the dynamic modeling of chemical processes, has been coupled with the PVM software to allow a single process model to be distributed over several computers running in parallel. As an initial application, this coarse distribution technique was applied to a batch chemical plant containing 16 unit operations. Computation time for this problem was reduced by a factor of 4.7 using only three parallel processors in the UNIX computing environment. Better than linear acceleration was achieved from the significant reduction in computation required to reinitialize the smaller subprocesses at discontinuities in the solution. The process was physically divided at points that naturally separated the overall plant into distinct subprocesses. This facilitated the computation by minimizing the interconnection between the parallel units. Techniques were developed to make efficient material and energy transfers between the modeled subprocesses based on actual material transfers used in plant operations.

Understanding and predicting the impact response of explosives and propellants remains a challenging area in the energetic materials field. Efforts are underway at LLNL (and other laboratories) to apply modern diagnostic tools and computational analysis to move beyond the current level of imprecise approximations towards a predictive approach more closely based on fundamental understanding of the relevant mechanisms. In this paper we will discuss a set of underlying mechanisms that govern the impact response of explosives and propellants: (a) mechanical insult (impact) leading to material damage and/or direct ignition; (b) ignition leading to flame spreading; (c) combustion being driven by flame spreading, perhaps in damaged materials; (d) combustion causing further material damage; (e) combustion leading to pressure build-up or relief; (f) pressure changes driving the rates of combustion and flame spread; (g) pressure buildup leading to structural response and damage, which causes many of the physical hazards. We will briefly discuss our approach to modeling up these mechanistic steps using ALE 3D, the LLNL hydrodynamic code with fully coupled chemistry, heat flow, mass transfer, and slow mechanical motion as well as hydrodynamic processes. We will identify the necessary material properties needed for our models, and will discuss our experimental efforts …

We present measurements of B-meson decays to the final states {eta}{prime} {rho}, {eta}{prime} f{sub 0}, and {eta}{prime} K*, where K* stands for a vector, scalar, or tensor strange meson. We observe a significant signal or evidence for {eta}{prime} {rho}{sup +} and all the {eta}{prime}K* channels. We also measure, where applicable, the charge asymmetries, finding results consistent with no direct CP violation in all cases. The measurements are performed on a data sample consisting of 467 x 10{sup 6} B{bar B} pairs, collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. Our results favor the theoretical predictions from perturbative QCD and QCD Factorization and we observe an enhancement of the tensor K*{sub 2} (1430) with respect to the vector K*(892) component.

Vascular stents are small tubular scaffolds used in the treatment of arterial stenosis (narrowing of the vessel). Most vascular stents are metallic and are deployed either by balloon expansion or by self-expansion. A shape memory polymer (SMP) stent may enhance flexibility, compliance, and drug elution compared to its current metallic counterparts. The purpose of this study was to describe the fabrication of a laser-activated SMP stent and demonstrate photothermal expansion of the stent in an in vitro artery model. A novel SMP stent was fabricated from thermoplastic polyurethane. A solid SMP tube formed by dip coating a stainless steel pin was laser-etched to create the mesh pattern of the finished stent. The stent was crimped over a fiber-optic cylindrical light diffuser coupled to an infrared diode laser. Photothermal actuation of the stent was performed in a water-filled mock artery. At a physiological flow rate, the stent did not fully expand at the maximum laser power (8.6 W) due to convective cooling. However, under zero flow, simulating the technique of endovascular flow occlusion, complete laser actuation was achieved in the mock artery at a laser power of {approx}8 W. We have shown the design and fabrication of an SMP stent and …

The National Ignition Facility (NIF), being constructed at Lawrence Livermore National Laboratory (LLNL), comprises 192 laser beams, Figure 1. The lasing medium is neodymium in phosphate glass with a fundamental frequency (1{omega}) of 1.053 {micro}m. Sum frequency generation in a pair of conversion crystals (KDP/KD*P) produces 1.8 Mj of the third harmonic light (3{omega} or {lambda}=0.35). On NIF the frequency conversion crystals are part of the Final Optics Assembly (FOA), whose two principal functions are to convert the laser light to 3{omega} and focus it on target. In addition, the FOA provides a vacuum window to the target chamber, smoothes the on- target irradiance profile, moves the unconverted light away from the target, and provides signals for alignment and diagnostics. The FOA has four Integrated Optics Modules (IOM), Figure 4, each of which contains two 41 cm square crystals are mounted with the full edge support to micro radian angular and micron flatness tolerances. This paper is intended to be an overview of the important factors that affect frequency conversion on NIF. Chief among these are angular errors arising from crystal growth, finishing, and mounting. The general nature of these errors and how they affect frequency conversion, and finally the …

Article reporting optical properties of twisted single-layer 2D+ moiré photonic crystals where there is a weak modulation in z direction, and bilayer moiré-overlapping-moiré photonic crystals. This study leads to a potential application of 2D+ moiré photonic crystal in future on-chip optoelectronic integration.

Article describes how the refractive index of a system is often viewed as the collective response of a medium to an electromagnetic field. By studying the propagation of a single photon interacting with a two-level atom, the authors examine the dispersion behavior, calculate the phase and group velocity of the photon wave packet, and further analyze the dispersion experienced by the photon.

Article describes how thiol-ene polymers are a promising class of biomaterials with a wide range of potential applications, including organs-on-a-chip, microfluidics, drug delivery, and wound healing. This study investigated the incorporation of di-acrylate chain extenders to improve the stretchability and conformability of those flexible thiol-ene polymers.

This is a correction to an article. The affiliation of the first author was published incorrectly.

Article describes how this study evaluates the effect of traffic light nutritional label attributes on children's food choices. The study's findings offer evidence that TL labels are effective in helping children make food choices consistent with their preferences for food products with TL labels representing healthier alternatives.