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A gentle vapor-diffusion technique for cross-linking of protein crystals for cryocrystallography

Carol J. Lusty1999-02-01Journal of Applied Crystallography

Protein crystals have been cross-linked by a gentle technique whereby glutaraldehyde is introduced by vapor diffusion into the crystallization droplet containing the crystals. Diffraction analyses of crystals of three different proteins show that cross-linking prevents, in a large part, the lattice disorder normally o…

Protein Structure and DynamicsEnzyme Structure and FunctionBiochemical and Molecular Research

Brownian dynamics simulation of a hard-sphere suspension

P. Strating1999-02-01Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics

In this paper we discuss the nonequilibrium shear viscosity of a suspension of hard spheres that is modeled by neglecting hydrodynamic interactions in a consistent way. The aim is to establish the true capabilities of this model in predicting the properties of real suspensions. A Brownian dynamics algorithm is used to…

Phase Equilibria and ThermodynamicsMaterial Dynamics and PropertiesRheology and Fluid Dynamics Studies

Nanophases in polymers

Eric Reynaud、C. Gauthier、José Cruz Núñez Pérez1999-02-01Revue de Métallurgie

Polymers have been reinforced by nanophases for a long time. Nevertheless recent technological progress have allowed to put forward new materials, confirming the reinforcing effect of nanoparticles in polymer. They also emphasize the importance of three main parameters in these nanostructured systems : the mechanical…

Polymer Nanocomposites and PropertiesDendrimers and Hyperbranched PolymersTribology and Wear Analysis

Differences in the Composition of Adhesive and Non-Adhesive Mucus From the Limpet Lottia limatula

A. M. Smith、T. J. Quick、R. Peter1999-02-01Biological Bulletin

The mucus used by the limpet Lottia limatula to form glue-like attachments was compared biochemically to the slippery mucus produced during other activities, such as suction adhesion. Colorimetric assays revealed the protein content of the adhesive mucus to be 2.1 times greater than that of the non-adhesive form, and…

Polymer Surface Interaction StudiesSilk-based biomaterials and applicationsCephalopods and Marine Biology

Ground and Excited State Electronic Properties of Halogenated Tetraarylporphyrins: Tuning the Building Blocks for Porphyrin-based Photonic Devices

Sung Ik Yang、Jyoti Seth、JON-PAUL STRACHAN 等 8 位作者1999-02-01Journal of Porphyrins and Phthalocyanines

The rational design of molecular photonic devices relies on the ability to select components with predictable electronic structure, excited state lifetimes and redox chemistry. Electronic communication in multiporphyrin arrays depends critically on the relative energies and electron density distributions of the fronti…

Porphyrin and Phthalocyanine ChemistryPhotochemistry and Electron Transfer StudiesLuminescence and Fluorescent Materials

Biochemical and Electron Microscopic Image Analysis of the Hexameric E1 Helicase

Erik T. Fouts、Xiong Yu、Edward H. Egelman 等 4 位作者1999-02-01Journal of Biological Chemistry

DNA replication initiator proteins bind site specifically to origin sites and in most cases participate in the early steps of unwinding the duplex. The papillomavirus preinitiation complex that assembles on the origin of replication is composed of proteins E1 and the activator protein E2. E2 is an ancillary factor tha…

DNA Repair MechanismsPhotosynthetic Processes and MechanismsEnzyme Structure and Function

TARGETING AND COVALENT MODIFICATION OF CELL WALL AND MEMBRANE PROTEINS HETEROLOGOUSLY EXPRESSED IN THE DIATOM CYLINDROTHECA FUSIFORMIS (BACILLARIOPHYCEAE)

Harald Fischer、Ingrid Robl、Manfred Sumper 等 4 位作者1999-02-01Journal of Phycology

Diatoms are unicellular organisms encased by silica‐based cell walls that display species‐specific structures. Morphogenesis of diatom cell walls is believed to be controlled by a polysaccharide/protein‐matrix that remains associated with mature cell walls. Recently, a family of calcium‐binding glycoproteins, the frus…

Genomics and Phylogenetic StudiesProtist diversity and phylogenyDiatoms and Algae Research

In situ structure determination of the high-pressure phase of Fe 3 O 4

Yingwei Fei、D. J. Frost、Ho‐kwang Mao 等 5 位作者1999-02-01American Mineralogist

The crystal structure of a high-pressure Fe 3 O 4 phase was determined by in situ X-ray diffraction measurements at high pressure and temperature, using an imaging plate detector and monochromatic synchrotron X-radiation. The high-pressure phase has the Pbcm space group (CaMn 2 O 4 -type structure) with cell parameter…

High-pressure geophysics and materialsRare-earth and actinide compoundsX-ray Diffraction in Crystallography

Control of Iron(II) Spin States in 2,2′:6′,2″-Terpyridine Complexes through Ligand Substitution

Edwin C. Constable、Gerhard Baum、Eckhard Bill 等 14 位作者1999-02-01Chemistry - A European Journal

Phenyl substituents in the 6-positions of terpyridine ligands are important for controlling the spin state of their iron(II) complexes. The introduction of phenyl substituents in both the 6- and 6″-positions leads exclusively to the orange high-spin iron(II) complexes, whilst the presence of a single 6-phenyl substitu…

Metal complexes synthesis and propertiesMagnetism in coordination complexesPorphyrin and Phthalocyanine Chemistry

Measuring induction period for calcium sulfate dihydrate precipitation

Amedeo Lancia、Dino Musmarra、Marina Prisciandaro1999-02-01AIChE Journal

Abstract Homogeneous nucleation of CaSO 4 ·2H 2 O (gypsum) based on an optical diagnostic technique was studied within a supersaturation range of 1–4 at 25–90°C. The experiments were carried out using an experimental apparatus consisting of a batch crystallizer with the related measurement devices. Signals of scattere…

Calcium Carbonate Crystallization and InhibitionMinerals Flotation and Separation TechniquesCrystallization and Solubility Studies

High-temperature phases of NaNbO3 and NaTaO3

C. N. W. Darlington、K. S. Knight1999-02-01Acta Crystallographica Section B Structural Science

The high-temperature phases of the perovskites sodium niobate, NaNbO(3), and sodium tantalate, NaTaO(3), have been re-examined using the high-resolution powder diffractometer HRPD at the ISIS neutron spallation source; the two materials show the same sequence of phases with tilted octahedra. Diffraction patterns were…

Ferroelectric and Piezoelectric MaterialsMicrowave Dielectric Ceramics SynthesisNuclear materials and radiation effects

Strain Hardening of Fractal Colloidal Gels

Thomas Gisler、R. C. Ball、D. A. Weitz1999-02-01Physical Review Letters

We report on experiments on the rheology of gels formed by diffusion-limited aggregation of neutrally buoyant colloidal particles. These gels form very weak solids, with the elastic modulus, ${G}^{\ensuremath{'}}(\ensuremath{\omega})$, larger than the loss modulus, ${G}^{\ensuremath{'}\ensuremath{'}}(\ensuremath{\omeg…

Hydrogels: synthesis, properties, applicationsMaterial Dynamics and PropertiesPolysaccharides Composition and Applications

Postsynthesis Hydrothermal Restructuring of M41S Mesoporous Molecular Sieves in Water

Laiyuan Chen、T. Horiuchi、Toshiaki Mori 等 4 位作者1999-02-01The Journal of Physical Chemistry B

A high-quality Si−MCM-41 was prepared with the composition of SiO 2, 0.2; TEAOH, 0.25; CTMABr, 35 in H 2 O using fumed silica as the silica source. The quality of the compounds was assessed using different analytical techniques such as XRD, N 2 adsorption−desorption measurement, UV−vis absorption, FTIR, and 29 Si MAS…

Metal-Organic Frameworks: Synthesis and ApplicationsZeolite Catalysis and SynthesisMesoporous Materials and Catalysis

Degree of branching in hyperbranched polymers. 3 Copolymerization of ABm-monomers with AB and ABn-monomers

Holger Frey、Dirk Hölter1999-02-01Acta Polymerica

Extending the considerations of previous work (Acta Polym. 1997, 48, 30; Acta Polym. 1997, 48, 298) the degree of branching (DB) and the average number of branches per non-terminal monomer unit (ANB) are defined and calculated for random copolycondensation of ABm with AB monomers as well as ABm with ABn-monomers in ge…

Advanced Polymer Synthesis and CharacterizationDendrimers and Hyperbranched PolymersSynthesis and properties of polymers

Double Exchange via Degenerate Orbitals

Jeroen van den Brink、D. I. Khomskiǐ1999-02-01Physical Review Letters

We consider the double exchange for systems in which doped electrons occupy degenerate orbitals, treating the realistic situation with double degenerate ${e}_{g}$ orbitals. We show that the orbital degeneracy leads in general to the formation of anisotropic magnetic structures and that, in particular, depending on the…

Magnetic and transport properties of perovskites and related materialsRare-earth and actinide compoundsAdvanced Condensed Matter Physics

A Radiation Dosimetry Method Using Pulsed Optically Stimulated Luminescence

M.S. Akselrod、S.W.S. McKeever1999-02-01Radiation Protection Dosimetry

A method for the determination of absorbed radiation dose is described based on pulsed optically stimulated luminescence (POSL). The method relies upon the stimulation of an irradiated sample with a train of light pulses from a suitable light source (e.g. a laser) using a wavelength which is within the range of wavele…

Luminescence Properties of Advanced MaterialsRadiation Detection and Scintillator TechnologiesLaser Design and Applications

Wall-Mediated Forces between Like-Charged Bodies in an Electrolyte

John C. Neu1999-02-01Physical Review Letters

The Poisson-Boltzmann model of colloidal bodies in electrolyte is the basis of a recent numerical calculation predicting attraction between two colloidal spheres confined in a cylinder. The present study formulates an analytical proof that this model cannot predict attraction. Our exact result, not contingent upon app…

Material Dynamics and PropertiesSpectroscopy and Quantum Chemical StudiesElectrostatics and Colloid Interactions

High-strength materials produced by precipitation of icosahedral quasicrystals in bulk Zr–Ti–Cu–Ni–Al amorphous alloys

Linzhuang Xing、J. Eckert、W. Löser 等 4 位作者1999-02-01Applied Physics Letters

Zr 62−x Ti x Cu 20 Ni 8 Al 10 (3⩽x⩽5) amorphous alloys crystallize via precipitation of icosahedral quasicrystals in the primary crystallization step, leading to nano-sized quasicrystals embedded in an amorphous matrix. Ti is the decisive component favoring the precipitation of quasicrystals. The mechanical properties…

Metallic Glasses and Amorphous AlloysQuasicrystal Structures and PropertiesMineralogy and Gemology Studies

Phase diagram of charge-stabilized colloidal suspensions: van der Waals instability without attractive forces

René van Roij、Marjolein Dijkstra、Jean-Pierre Hansen1999-02-01Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics

A careful analysis of the classic Derjaguin-Landau-Verwey-Overbeek theory of the interaction energy in a suspension of charge-stabilized, spherical colloidal particles (polyions) in the presence of salt shows that in addition to the usual screened-Coulomb effective pair interaction between polyions, there exists a str…

Material Dynamics and PropertiesSpectroscopy and Quantum Chemical StudiesElectrostatics and Colloid Interactions