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Biosynthesis of Riboflavin. Studies on the Reaction Mechanism of 6,7-Dimethyl-8-ribityllumazine Synthase

K. Kis、R. Volk、Adelbert Bacher1995-03-07Biochemistry

The lumazine synthase/riboflavin synthase complex of Bacillus subtilis consists of an icosahedral capsid of 60 beta subunits surrounding a core of 3 alpha subunits. The beta subunits catalyze the condensation of 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione with (3S)-3,4-dihydroxy-2-butanone under formation of 6,7…

Folate and B Vitamins ResearchEnzyme Structure and FunctionBiochemical and Molecular Research

Structural changes induced by hydrogen absorption in palladium and palladium–ruthenium alloys

A.L. Cabrerα、Erie Morales L.、J. Hasen 等 4 位作者1995-03-06Applied Physics Letters

The structural changes in Pd and Pd–Ru alloys induced by the repeated absorption–desorption of hydrogen have been studied. It is found that absorption–desorption cycles produce structural changes in Pd whereas the addition of small amounts of Ru inhibits these hydrogen-induced changes. The experimental results show th…

Advanced Chemical Physics StudiesHydrogen Storage and MaterialsCold Fusion and Nuclear Reactions

Shear Alignment and Instability of Smectic Phases

Mark Goulian、Scott T. Milner1995-03-06Physical Review Letters

We consider the shear flow of well-aligned one-component smectic phases, such as thermotropic smectics and lamellar diblock copolymers, below the critical region. We show that, as a result of thermal fluctuations of the layers, parallel $\left(c\right)$ alignment is generically unstable and perpendicular $\left(a\righ…

Liquid Crystal Research AdvancementsRheology and Fluid Dynamics StudiesBlock Copolymer Self-Assembly

Hillock formation during electromigration in Cu and Al thin films: Three-dimensional grain growth

A. Gladkikh、Y. Lereah、Evgeny E. Glickman 等 6 位作者1995-03-06Applied Physics Letters

The evolution of microstructure in Al and Cu thin film lines during electromigration has been studied using a transmission electron microscopy. Grain boundary migration was found to be critically involved in the electromigration induced hillock formation that can be described as a three-dimensional growth of a single…

Corrosion Behavior and InhibitionCopper Interconnects and ReliabilitySurface and Thin Film Phenomena

Magnetism and Phase Separation in Polymeric Hubbard Chains

A. M. S. Macêdo、María Cristina dos Santos、M. D. Coutinho-Filho 等 4 位作者1995-03-06Physical Review Letters

We study a class of one-dimensional chains whose topology leads to flatbands in the electronic spectrum. Using the Hubbard model, we find that these materials should exhibit ferrimagnetic ordering for a half-filled band, in agreement with a theorem by Lieb. Away from half filling the system displays a very rich magnet…

Physics of Superconductivity and MagnetismAdvanced Sensor and Energy Harvesting MaterialsConducting polymers and applications

The concentration-depth profile at the surface of a solution of tetrabutylammonium iodide in formamide, based on angle-resolved photoelectron spectroscopy

F Eschen、M Heyerhoff、Harald Morgner 等 4 位作者1995-03-06Journal of Physics Condensed Matter

We have investigated a solution of tetrabutylammonium iodide (TBAI) in the polar solvent formamide (FA) using angle-resolved photoelectron spectroscopy at the Berlin Electron Storage Ring for Synchrotron Radiation (BESSY). The concentration was set to 0.5 molality. We have evaluated the signals from C 1s pertaining to…

Advancements in Photolithography TechniquesElectron and X-Ray Spectroscopy TechniquesSurface and Thin Film Phenomena

Anomalous Diffusion at Liquid Surfaces

Oleg V. Bychuk、Ben O’Shaughnessy1995-03-06Physical Review Letters

We study the role of bulk-surface exchange in the diffusion of adsorbed molecules at liquid-solid and liquid-fluid interfaces. For ``strong adsorbers'' (readsorption time much less than desorption time) we find anomalous surface diffusion on time scales less than the surface retention time: Displacement moments grow a…

Material Dynamics and PropertiesTheoretical and Computational PhysicsElectrostatics and Colloid Interactions

On thermoelastic phenomena around orientational ordering transition in crystalline C60

M. A. Fradkin1995-03-05arXiv

Thermoelastic phenomena associated with orientational phase transition in solid C60 are considered. Coupling of the order parameter with elastic strain is analyzed in the Landau theory of phase transitions. Wide range of possible coexistence of the FCC phase with SC one in C60 has been found from 260 K down to critica…

chem-phcond-matmtrl-th

A Structure Model and Growth Mechanism for Multishell Carbon Nanotubes

S. Amelinckx、D. Bernaerts、X. B. Zhang 等 5 位作者1995-03-03Science

A model that postulates a mixture of scroll-shaped and concentric, cylindrical graphene sheets is proposed to explain the microstructure of graphite multishell nanotubes grown by arc discharge. The model is consistent with the observed occurrence of a relatively small number of different chiral angles within the same…

Carbon Nanotubes in CompositesGraphene research and applicationsFullerene Chemistry and Applications

Ab initio studies of structural instabilities in magnesium silicate perovskite

M. C. Warren、G. J. Ackland1995-03-02arXiv

Density-functional simulations are used to calculate structural properties and high-symmetry phonons of the hypothetical cubic phase, the stable orthorhombic phase and an intermediate tetragonal phase of magnesium silicate perovskite. We show that the structure of the stable phase is well described by freezing in a sm…

Materials Sciencemtrl-th

Modelling the heat release rate of aircraft cabin panels in the cone and OSU calorimeters

William J. Parker、Robert Filipczak1995-03-01Fire and Materials

Abstract A computer model was developed to calculate the heat release rate of aircraft cabin panels in the OSU calorimeter based on their thermophysical, thermochemical and geometrical properties. It calculates the temperature profile through the panel as a function of time and uses the measured kinetic constants of t…

Energetic Materials and CombustionFire dynamics and safety researchThermal and Kinetic Analysis

Simulation of the IAEA’s Fourth Standard Problem Exercise Small-Break Loss-of-Coolant Accident Using RELAP5/MOD3.1

Peter Cebull、Yassin A. Hassan1995-03-01Nuclear Technology

A small-break loss-of-coolant accident experiment conducted at the PMK-2 integral test facility in Hungary is analyzed using the RELAP5/MOD3.1 thermal-hydraulic code. The experiment simulated a 7.4% break in the cold leg of a VVER-440/213-type nuclear power plant as part of the International Atomic Energy Agency’s Fou…

Nuclear reactor physics and engineeringNuclear Materials and PropertiesNuclear Engineering Thermal-Hydraulics

The relationship between structure and deformation behavior of sulfone polymers

Hsien‐Tang Chiu、Dao‐Shinn Hwung1995-03-01Polymer Engineering and Science

Abstract The deformation of three types of sulfone polymers—polysulfone (PSF), poly(ether sulfone) (PESF), and polyarylsulfone (PASF)—was performed with a mechanical testing system (MTS). The result and samples were studied using a transmission electron microscope (TEM), a dynamic mechanical analyzer (DMA), and a diel…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesTribology and Wear Analysis

The influence of ionic and elastic effects on partial switching in ferroelectric liquid crystal devices

D. C. Ulrich、Steve J. Elston1995-03-01Liquid Crystals

The simultaneous influences of elastic stress and ionic fields on switching in ferroelectric liquid crystals are considered. Experiments are performed which show that the combined influences can be quite complex. When a reset pulse is applied, it can enhance or decrease the previous ionic field, as well as change the…

Liquid Crystal Research AdvancementsPhase-change materials and chalcogenidesAdvanced Materials and Mechanics

Orientational Order Parameters in the Smectic C and Nematic Phase of Heptyloxyazoxybenzene (HAB)

B. Adhikari、Ranjit Kumar Paul1995-03-01Molecular crystals and liquid crystals science technology. Section A, Molecular crystals and liquid crystals/Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals

Orientational order parameters (OOP) in the smectic C and nematic phases of heptyloxyazoxybenzene (HAB) have been determined from x-ray diffraction and refractive index studies. Order parameters determined from x-ray studies have been corrected for the random orientation of the director in a cone in the smectic C phas…

Liquid Crystal Research AdvancementsSynthesis and Properties of Aromatic CompoundsMolecular spectroscopy and chirality

Tritium Process Applications Using SAES Getters for Purification and Collection from Inert Gas Streams

D. H. Meikrantz、Joy Don Baker、Gary L Bourne 等 7 位作者1995-03-01Fusion Technology

A zirconium alloy getter-based tritium monitoring and collection system has been designed, built, and subsequently operated for three years at the Idaho National Engineering Laboratory. The system is automated to provide separation of tritium from 41Ar, collection of tritium on an hourly basis, unloading of getters fo…

Fusion materials and technologiesNuclear reactor physics and engineeringHydrogen Storage and Materials

Magnetische Wechselwirkungen in Inselstrukturen ternärer Cobaltchalkogenide. Die Spinstrukturen von Na 6 CoS 4 und Na 6 CoSe 4

W. Bronger、W. Koelman、Paul Müller1995-03-01Zeitschrift für anorganische und allgemeine Chemie

Abstract Die Natriumcobaltchalkogenide Na 6 CoS 4 und Na 6 CoSe 4 sind durch isolierte [CoX 4 ]‐Einheiten charakterisiert. Trotz der großen Abstände der magnetischen Zentren von über 6Å führen bei tiefen Temperaturen magnetische Wechselwirkungen zu dreidimensional geordneten Spinstrukturen, die über Neutronenbeugungsu…

Crystal Structures and PropertiesSolid-state spectroscopy and crystallographyInorganic Chemistry and Materials

Fusion behavior of plastisols of PVC studied by ATR‐FTIR

A. Marcilla、M. Beltrán、Jean Charles Garcia 等 4 位作者1995-03-01Journal of Vinyl and Additive Technology

Abstract The behavior of PVC plastisols during gelation and fusion was studied by the ATR‐FTIR technique (Attenuated Total Reflectance‐Fourier Transform Infrared Spectroscopy). DBP, DOP, and DIDP, three common phthalate plasticizers for PVC, were used in plastisols formulations. Three heating rates—5, 10 and 15°C/min—…

Effects and risks of endocrine disrupting chemicalsPolymer Science and PVC

Ein neuer Typ ternärer Cobaltsulfide A 9 Co 2 S 7 (A \documentclass{article}\pagestyle{empty}\begin{document}$ \buildrel \wedge \over = $\end{document} K, Rb, Cs) mit trigonalplanaren [CoS 3 ]‐Baugruppen des zwei‐ und dreiwertigen Cobalts

W. Bronger、W. Koelman、D. Schmitz1995-03-01Zeitschrift für anorganische und allgemeine Chemie

Abstract Durch Schmelzreaktionen von Alkalicarbonat mit Cobalt und Schwefel im Wasserstoffstrom gelang die Darstellung der Verbindungen K 9 Co 2 S 7 , Rb 9 Co 2 S 7 und Cs 9 Co 2 S 7 . Die Struktur der Kaliumverbindung konnte über röntgenographische Untersuchungen an Einkristallen bestimmt werden (Raumgruppe P2 1 3, Z…

Crystal Structures and PropertiesAdvanced Condensed Matter PhysicsIron-based superconductors research

Influence of stress condition on initiation of magnetostriction in grain oriented silicon steel

H. Masui1995-03-01IEEE Transactions on Magnetics

It is commonly known that the magnetostriction of grain oriented silicon steel for electric transformers, is strongly influenced by applied stress on the steel as well as coating stress of the steel and is dominated exclusively by the formation of 90/spl deg/ domain walls. A new concept on a condition for the formatio…

Microstructure and Mechanical Properties of SteelsShape Memory Alloy TransformationsMagnetic Properties and Applications