Showing papers by "Environmental Molecular Sciences Laboratory published in 1994"
TL;DR: A high degree of correlated atomic motions in each of the domains and, to a lesser extent, anticorrelated motions between the two domains were found in the native T4 lysozyme molecular dynamics simulation.
Abstract: Hinge-bending in T4 lysozyme has been inferred from single amino acid mutant crystalline allomorphs by Matthews and coworkers. This raises an important question: are the different conformers in the unit cell artifacts of crystal packing forces, or do they represent different solution state structures? The objective of this theoretical study is to determine whether domain motions and hinge-bending could be simulated in T4 lysozyme using molecular dynamics. An analysis of a 400 ps molecular dynamics simulation of the 164 amino acid enzyme T4 lysozyme is presented. Molecular dynamics calculations were computed using the Discover software package (Biosym Technologies). All hydrogen atoms were modeled explicitly with the inclusion of all 152 crystallographic waters at a temperature of 300 K. The native T4 lysozyme molecular dynamics simulation demonstrated hinge-bending in the protein. Relative domain motions between the N-terminal and C-terminal domains were evident. The enzyme hinge bending sites re...
21 citations
TL;DR: In this paper, the role of impurity on dissolution is discussed in terms of preferential adsorption of impurities on kink sites on CaCO3(1014) surface in clean and impurity containing aqueous environments.
Abstract: Atomic force microscopy (AFM) has been used to study dissolution of the cleaved CaCO3(1014) surface in clean and impurity containing aqueous environments. In the clean solution, dissolution was found to occur by retreat of steps and creation of rhombohedral pits on a surface. Dissolution is anisotropie with two different step velocities differing by a factor of 2.3, resulting from different atomic step structures. Dissolution is partially changed after adding impurities in the solution via rounding of the fastest dissolution corner of rhombohedral pits and slowing down the step velocity in that direction. The role of impurity on dissolution is discussed in terms of preferential adsorption of impurities on kink sites.
8 citations
22 Aug 1994
TL;DR: This paper proposes two new load balancing schemes and evaluates their performance for ray tracing on parallel processors, term the new methods 'local distributed control' (LDC) and 'global distributed control (GDC).
Abstract: Ray tracing is one of the computer graphics techniques used to render high quality images. Unfortunately, the ray tracing of complex scenes can require large amounts of CPU time, making the technique impractical for everyday use. Since the ray tracing calculations that determine the values of individual pixels are independent, this appears to be an easy problem to parallelize, and parallel algorithms have been proposed. However, pixel computation times can vary significantly, and naive attempts at parallelization give poor speedup due to the load imbalance between the processors. The key to achieving high parallel efficiency is to ensure that the computational load is evenly balanced. In this paper, we propose two new load balancing schemes and evaluate their performance for ray tracing on parallel processors. We term the new methods 'local distributed control' (LDC) and 'global distributed control' (GDC). Our new strategies are complementary: GDC performs forms well for high computational complexity images and LDC works well for low computational complexity images. >
2 citations
TL;DR: In this paper, a molecular beam epitaxy (MBE) structure of MgO and a random bcc alloy of 70% Cr and 30% Mo is matched to obtain high-energy electron diffraction (RHEED), XPS/XPD, and transmission electron microscopy (TEM).
Abstract: We have grown by molecular beam epitaxy (MBE) structurally coherent layers of MgO and a random bcc alloy of 70% Cr and 30% Mo to which MgO is lattice matched. Specimens werecharacterized by means of reflection high-energy electron diffraction (RHEED), x-ray photoelectron spectroscopy and diffraction (XPS/XPD), transmission electron microscopy (TEM), and atomic force microscopy (AFM). These systems exhibit excellent long- and shortrange crystallographic order, as well as nearly perfect structural coherence across the interface.
1 citations
TL;DR: In this article, the authors investigated the formation of three dimensional islands (clusters) from the vapor deposition of Cu overlayers on a nearly stoichiometric SrTiO3(001) surface at ambient temperature.
Abstract: Copper overlayers deposited on nearly stoichiometric SrTiO3(001) have been investigated with scanning tunneling microscopy (STM). Vapor deposition of Cu on a SrTiO3(001) surface at ambient temperature leads to the formation of three dimensional islands (clusters). The distribution of Cu islands appears to be inhomogeneous with two characteristic morphologies. In regions with a low density of Cu islands the Cu was always associated with step edges or defect sites. In regions with a high density of Cu islands the islands exhibit a random but nearly close packed morphology. The variation of Cu island density is indicative of diffusion of Cu clusters on the SrTiO3(001) surface. Diffusion was further confirmed by annealing the Cu/SrTiO3 at elevated temperatures yielding agglomeration of Cu clusters.
TL;DR: In this paper, the PANi-Pd composite materials behaved electrochemically different than PANi film alone or Pd film deposited in sulfuric acid with palladium salt, and they were investigated by applying electrochemical, UV-visible spectroscopic and surface microscopy techniques.
Abstract: Electrosynthesized polyaniline (PANi) can be chemically functionalized by incorporation of palladium clusters. The functionalization of electrochemically, freshly prepared and dried PANi film occurs spontaneously during the relaxation process. This process is carried out in sulfuric acid containning palladium salt. The material properties of the new composite PANi-Pd film were investigated by applying electrochemical, UV-visible spectroscopic and surface microscopy techniques. The PANi-Pd composite materials behaved electrochemically different than PANi film alone or Pd film deposited electrochemically. This finding is particularly important for developing layers for chemical sensors, electrocatalysis or supercapacitors applications.