bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influences of Interfacial Properties on High-Performance Concrete Composites
Authors: Roy D.M. , Jiang W. 
Published: April 2011

AbstractThere is a strong motivation to study the interfacial properties of concrete composites because the interfacial region is often the phase where fracture first develops. The aim of this study is to understand phenomena which are unique at high-performance concrete composite interfaces, and how these influence the bulk properties of a concrete composite. Since processes at interfaces must be considered over a range of scales varying from the atomic to the macroscopic, multidisciplinary research approaches are desirable. Model cement/rock (aggregate) and matrix/fiber interaction experiments were carried out. Morphology and microstructure of interfacial regions among mortar/rock, and fiber/matrix were examined utilizing SEM. Computer image analysis performed along a perpendicular to the interface revealed compositional and physical irregularities. The variations in the volume of pores adjacent to interface zones are documented and supported by microscopic observation. The influences of interfacial properties on concrete composite strength and durability are discussed, and influences of fibers on the fracture and fracture resistance behavior are also discussed. Analyses of debonding along interfaces are used to define the role of debonding in fiber-reinforced concrete composites.
Mechanical and Microstructural Investigation of the Aggregate and Cement Interface
Authors: Li Zongjin , Shah Surendra P. , Aquino Matthew J. 
Published: April 2011

AbstractThe understanding of the interface between aggregate and cement is crucial in determining the properties of concrete. Recently, a pushout experimental technique and a theoretical model have been developed to determine the stiffness, strength and surface energy of the interface layer. The validity of these material parameters was verified in the present study by examining the effect of diameter and embedment length of aggregate. In addition, the effect of the pretreatment of aggregate surface and various admixtures was investigated. All pushout tests were performed in a closed-loop manner to obtain the load vs. displacement relationship.The interfacial zone was further investigated by using backscattered electron imaging and energy dispersive analysis of x-rays (EDAX) to characterize the microstructure of the interface. The relationship between mechanical properties and microstructure of interfacialzone was studied. It was shown that the microstructure of the interface plays a substantial role in the mechanical behavior of the aggregate/cement bond.
Modelling the D.C. Electrical Conductivity of Mortar
Authors: Garboczi E.J. , Schwartz L.M. , Bentz D.P. 
Published: April 2011

AbstractThe interfacial zone separating cement paste and aggregate in mortar and concrete is believed to influence many of the properties of these composites. This paper presents a theoretical framework for quantitatively understanding the influence of the interfacial zone on the overall electrical conductivity of mortar, based on realistic random aggregate geometries. These same ideas may also be used to approximately predict the fluid permeability of mortar.
Moisture Permeability of Mature Concrete and Cement Paste
Authors: Hedenblad Göran 
Published: April 2011

AbstractMoisture permeabilities (δv,) of mature concrete and cement paste with water-cement ratio (wo/C) 0.4, 0.5 and 0.6 have been determined as functions of the relative humidity (RH). These δv, can be used to calculate δv, of the aggregates including the interfacial transition zone (ITZ). δv, of granite has been preliminarily determined as a function of RH.
Fiber-Matrix Interfacial Area Reduction in Fiber Reinforced Cements and Concretes at Moderate to High Fiber Volume Fractions
Authors: Karam Gebran N. 
Published: April 2011

AbstractThe area and properties of the fiber-matrix interface in fiber reinforced cements and concretes determines the amount of stress transferred forth and back between the cement paste and the reinforcement and hence controls the mechanical properties of the composite. Fiber-fiber interaction and overlap of fibers with fibers, voids and aggregates can dramatically decrease the efficiency of the reinforcement by reducing this interfacial area. A simple model to account for this reduction is proposed and ways to integrate it in the models describing the mechanical properties of short fiber reinforced concretes are presented. The parameters of the model are evaluated from previously published data sets and its predictions are found to compare well with experimental observations; for example, it is able to predict the non-linear variation of bending and tensile strength with increasing fiber volume fraction as well as the existence of an optimal fiber content.
New Anion Exchangeable Layered Mixed Basic Salt, Ni1-xZn2x(OH)2(OCOCH3)2x·nH2O
Authors: Yamanaka Shoji , Ando Kazunari , Ohashi Masao 
Published: April 2011

AbstractA new anion exchangeable layered compound with a composition of Ni1-xZn2x(OH)2(OCOCH3)2x·nH2O (0.15 < x < 0.25) was prepared by hydrothermal hydrolysis of Ni-Zn mixed acetate solutions. The structure is related to zinc basic salts such as Zn5(OH)8Cl2·nH2O and Zn5(OH)8Cl2·nH2O; nickel ions form brucite-type hydroxide layers with vacanciesNi1-x(OH)2, and zinc ions occupy the tetrahedral sites above and below the vacant sites outside the hydroxide layers. Acetate ions are weakly bound to the Zn2+ ions, completing the tetrahedra, and easily exchanged with most of inorganic as well as organic anions. The reactions are reversible. Exchange with [Si8O20]8- ions resulted in the formation of two-dimensional silicate layers analogous to those of 2:1 type clay minerals.
Porous Spheroidal Hydrotalcite Aggregates
Authors: D. Cox Sherman , J. WISE Kenneth 
Published: April 2011

AbstractControlled precipitation conditions allow the formation of highly porous, spheroidal aggregates of hydrotalcite. The aggregate structure resembles a house-of-cards, being composed of interconnected thin plates. The aggregate size can vary over a range of about 1 to 60 μm by altering precipitation conditions such as mixing shear, temperature, addition rates and addition order. These materials are low in bulk density and highly absorptive. The aggregate structure is maintained during calcination. The micro and meso-pore size distribution is very similar to conventionally prepared hydrotalcite, but the macroporosity is dominated by the voids between spheroids. The characteristics of these aggregates point to potential applications in areas such as catalysis and separation.
Preparation and Properties of Clays Pillared with Al2O3-NiO Mixed Oxide
Authors: Yamanaka Shoji , Yamamoto Hironori 
Published: April 2011

AbstractMontmorillonite was pillared with Al2O3-NiO mixed oxide by ion-exchange combined with titration process; the interlayer Na ions of montmorillonite were first exchanged with aluminum hydroxide polycations, and then nickel hydroxide was precipitated between the layers by a titration method. The aluminum hydroxide pillars reacted with the nickel hydroxide at room temperature, and the microporous structure was much stabilized against heating. The specific surface area as high as 300 m2/g was maintained up to 700°C.
Rectorite Pillared with Ce-Modified Aluminum Oxide
Authors: Wu Jianxin , Rakiewicz Edward F. , Gatte Robert R. 
Published: April 2011

AbstractRectorite clay was pillared with an Al/Ce-cluster pillaring agent made from aluminum chlorhydrol and cerium nitrate. The resulting product had an interlayer distance of 15.7 Å, which was significantly larger than the interlayer distance obtained using conventional aluminum chlorhydrol as the pillaring agent (8.4 Å). Argon adsorption analysis indicates that the pores of the AL/Ce-cluster pillared rectorite are non-uniform, with pore diameters ranging from 5 to 16Å. 29Si MAS NMR studies showed that calcining the natural rectorite changes the silicon environment, while the pillared rectorite clays are much more resistant to such changes upon calcination. It is suggested that pillaring reactions enhance the thermal stability of the rectorite by stabilizing the local silicon environment in the clay.
The Synthesis of an Interstratified Layered Oxide from Exfoliated Precursors
Authors: Smith Richard L. , Rohrer Gregory S. 
Published: April 2011

AbstractAqueous suspensions of exfoliated Li0.25MoO3 and Na-montmorillonite have been combined and dried to form interstratified solids. X-ray diffraction patterns of ethylene glycol treated films show that the d-spacing of restacked materials varies with composition between the limits established by the two end members. Based on these data, we conclude that the new materials are composed of individual layers from each of the precursor compounds, arranged in a random fashion. It is likely that other layered solids can be exfoliated and restacked to form new interstratified materials.
Processing and Characterization of High Porosity Aerogel Films
Authors: Hrubesh Lawrence W. , Poco John F. 
Published: April 2011

AbstractAerogels are highly porous solids having unique morphology among materials because both the pores and particles making up the material have sizes less than wavelengths of visible light. Such a unique morphology modifies the normal molecular transport mechanisms within the material, resulting in exceptional thermal, acoustical, mechanical, and electrical properties. For example, aerogels have the lowest measured thermal conductivity and dielectric constant for any solid material. Special methods are required to make aerogel films with high porosity. In this paper, we discuss the special conditions needed to fabricate aerogel films having porosities greater than 75% and we describe methods of processing inorganic aerogel films having controllable thicknesses in the range 0.5 to 200 micrometers. We report methods and results of characterizing the films including thickness, refractive index, density (porosity), and dielectric constant. We also discuss results of metallization and patterning on the aerogel films for applications involving microminiature electronics and thermal detectors.
Synthesis and Structure of Ultrafine Zeolite KL (LTL) Crystallites and their Use for Thin Film Zeolite Processing
Authors: Tsapatsis Michael , Okubo Tatsuya , Lovallo Mark , Davis Mark E. 
Published: April 2011

AbstractSynthesis conditions were identified leading to agglomerates of nearly cylindrical zeolite nanocrystals with dimensions less than 50 nm in the channel direction and approximately 10 nm in diameter (in the direction perpendicular to the zeolite channels). The nanocrystals form agglomerates with approximate particle sizes ranging from 20 to 400 nm as determined by DLS. Washing with repeated centrifugation and sonication results in stable (over long periods of time) colloidal suspensions of the zeolite particles in water (pH ∼ 7) with zeolite concentrations of lOg/l. The average zeolite particle size of the suspension can be as low as 20 nm as determined by DLS. Films free of microcracks were prepared from these suspensions by evaporation of water.
A New Templating Route to Ordered Mesoporous Materials
Authors: Tanev Peter T. , Pinnavaia Thomas J. 
Published: April 2011

AbstractA new templating route to ordered mesoporous materials is demonstrated based on hydrogen bonding interactions and self-assembly between neutral primary amine surfactants (S°) and neutral inorganic precursors (1°). The S° I° templating pathway affords ordered mesoporous materials with thicker framework walls, smaller X-ray scattering domain sizes, and substantial textural mesoporosities in comparison to MCM-41 materials templated with quaternary ammonium cations. This synthetic strategy also allows for the facile, environmentally benign recovery of the cost-intensive template by simple solvent extraction methods.
Spectroscopic Investigations of Mesoporous M41S Silica Phases
Authors: FrÖBa Michael , Behrens P. , Wong Joe , Engelhardt G. , Haggen-Müller CH. , Van De Goor G. , Rowen M. , Tanaka T. , Schwieger W. 
Published: April 2011

AbstractMesoporous silica phases of the M41S type were investigated by SiK XANES spectroscopy and the results compared with the information provided by 29Si MAS NMR spectroscopy. The results show that the pore walls are more ordered than in “truly” amorphous silica phases (as, e.g., glass) and indicate a relationship of their structure to layered silicates.
Production of Hollow Microspheres for Inertial Confinement Fusion Experiments
Authors: Cook Robert 
Published: April 2011

AbstractThe targets used in inertial confinement fusion (ICF) experiments at the Lawrence Livermore National Laboratory are plastic capsules roughly 0.5 mm in diameter. This paper reviews the fabrication of these capsules, focusing on the production of the thinwalled polystyrene microshell mandrel around which the capsule is built. The relationship between the capsule characteristics, especially surface finish, and capsule performance is discussed, as are the methods of surface characterization and modification necessary for experiments designed to study the effects of surface roughness on implosion dynamics. Targets for the next generation of ICF facilities using more powerful laser drivers will have to be larger while meeting the same or even more stringent symmetry and surface finish requirements. Some of the technologies for meeting these needs are discussed briefly.
Automated Line Development for Control and Selection of Shells for Laser Fusion Target
Authors: Veselov A. V. , Beinik A. Ja. , Zaharov A. V. , Inozemtsev A. P. , Komleva G. V. , Punin W. T. 
Published: April 2011

AbstractMethods for control of the shell diameter, wall thickness and wall nonuniformity and also methods for selection of shells in fluid have been developed and investigated. The methods allow us to separate shells according to the diameter with 0.25 μ;m accuracy, to the wall nonuniformity with 5–7% accuracy, to make measurements of the diameter with 0.35 μ;m accuracy and wall thickness with 3–10%.These methods allowed us to develop the automated process cycle of control and selection of shells for laser fusion targets. A model automated line has been developed and joint operation of units has been investigated. The calculated automated line throughput during the shell analysis is 50–300 shells per hour, the control and selection accuracy for the diameter, thickness, and wall nonuniformity is 1%, 3–10% and 1–3%, respectively.Thus the foundations have been laid for an automated, high-quality target production technology for power stations based on laser fusion.
Fabrication Method for Hollow Microspheres Made of High-Strength Glasses
Authors: Dorogotovtsev Valery M. 
Published: April 2011

AbstractLasting storage of hydrogen, its isotopes and other gases under high (1–2 thousand atm) pressure inside hollow microspheres as well as production of low-density syntaxis poroplasts to withstand high external loads - all these need hollow microspheres of high mechanical strength. By modern commercial technology the microspheres are mainly obtained from water- soluble alkali-silicate or alkali-boro-silicate glasses. These microspheres are not strong, their strength being 1000–1500 MPa.. Besides the low resistivity to hydrolysis and chemicals also restrict their applications. To gain strength 1.5–2 times higher the additional modification of microspheres is done either by leaching, or by annealing, or by ion exchange. Microspheres of stronger glasses being usually multi-component require a technology fitted to produce highly uniform glass [1,2].A new fabrication method is presented to produce hollow microspheres of various glasses. They include simple alkali and alkali-boro-silicate glasses as well as multi-component glasses of commercially available compositions, alkali-free, refractory, and high-strength glasses.
Synthesis and Characterization of PZT Coatings on Glass Microspheres
Authors: Jardine A. Peter 
Published: April 2011

AbstractSynthesis of Pb(Ti,Zr)O3 (PZT) coatings onto glass microspheres was demonstrated using solgel techniques. Characterization of the coatings was performed using XRD and SEM to demonstrate that piezoelectric PZT coating are possible. This study represents an initial feasibility study into the manufacture of so-called “smart” material fabrication utilizing different geometries.
Compressive Deformation of Hollow Microsphere Reinforced Metal Matrix Composites
Authors: Kiser M. T. , He M. , Wuj B. , Zok F. W. 
Published: April 2011

AbstractThe compressive deformation characteristics of hollow alumina microsphere reinforced aluminum matrix composites have been studied through both experiments and finite element analysis of unit cell models. Tests have been performed on composites containing around 50 volume percent of microspheres. The effects of the matrix flow stress and microsphere morphology (characterized by the ratio of wall thickness to radius) have been examined. The measured strength enhancement due to the hollow microspheres was found to be considerably less than that predicted by the FEM calculations; a result of microsphere cracking. Experiments have been conducted to document the progression of such damage following casting and mechanical deformation. The potential of this class of composite for impact energy absorption applications is also explored.
A Method for Rotation of Spherical Shells by Any Law with a Small Center Beating.
Authors: Veselov A. V. , Golubinskij A. G. , Zaharov A. V. , Malkov A. V. 
Published: April 2011

AbstractTo provide control of the whole surface the shell should be rotated. But the shell center beating within 1 μm gives thickness variations from 90 to 1200 Å. For high accuracy of measurements it is necessary to decrease the shell center beating upon rotation down to 0.1–0.2 μm. This problem can be solved using the proposed method for rotation of shells.Several units for rotation of shells have been developed and investigated. Those laws of rotation have been selected which allow to inspect the whole surface of the sell.Obvious advantages of the proposed method are the following: ease of installation and removal of the shell in the unit, automated installation of the shell in the desired position, high speed of rotation, small beating of the shell center during its rotation, wide access to the shell surface to be controlled, any required law of the shell rotation.
Fiber-Optic Microsensors Using Porous, Dye-Doped Silica Gel Microspheres
Authors: Pope Edward J. A. 
Published: April 2011

AbstractDye-doped porous silica microspheres can be prepared from liquid solution at temperatures near ambient. Microsphere diameter can be controlled between approximately 5.0 microns to in excess of a millimeter. The resulting microspheres can be attached to the distal end of an optical fiber in which the proximal end is attached to a spectrophotometer. Depending upon the organic species doped into the microsphere, a wide variety of sensing functions are possible. In this paper, the use of microsensors for measuring pH, temperature, and solvent content of aqueous solutions is demonstrated. Potential utility of this type of sensor to heavy metals detection and biomedical diagnostics is also discussed.
Controlled Multi-Stage Self-Assembly of Vesicles
Authors: Walker Scotr A. , Chiruvolu S. , Zasadzinski J. A. , Schmitt F.-J. , Israelachvlli J. N. 
Published: April 2011

AbstractThe association of lipid or surfactant molecules into spherical vesicles in solution constitutes a primary self-assembly process, although typical vesicles are not the equilibrium form of aggregation for most lipids. Such meta-stable vesicles can undergo a secondary self-assembly into higher order structures in a controlled and reversible manner by means of site-specific ligandreceptor coupling. Cryo-electron microscopy shows these structures to be composed of tethered vesicles in their original, unstressed state. In contrast, vesicles aggregated by non-specific forces are deformed. In this work, we show that equilibrium vesicles can also undergo a secondary selfassembly via ligand-receptor interactions, as evidenced by freeze-fracture electron microscopy. Such site-specific vesicle aggregation provides a practical mechanism for the production of stable, yet controllable, microstructured materials.
Magnetic X-Ray Circular Dichroism in Spin-Polarized Photoelectron Diffraction
Authors: Waddill G. D. , Tobin J. G. , Guo X. , Tong S. Y. 
Published: April 2011

AbstractThe first structural determination with spin-polarized, energy-dependent photoelectron diffraction using circularly-polarized x-rays is reported for Fe films on Cu(001). Circularly-polarized x-rays produce spin-polarized photoelectrons from the Fe 2p doublet, and intensity asymmetries in the 2p3/2 level are observed. Fully spin-specific multiple scattering calculations reproduce the experimentally-determined energy and angular dependences. A new analytical procedure which focuses upon intensity variations due to spin-dependent diffraction is introduced. A sensitivity to local geometric and magnetic structure is demonstrated.
Resonant Soft X-Ray Fluorescence Studies of Novel Materials
Authors: Carlisle J. A. , Shirley E. L. , Terminello L. J. , Hudson E. A. , Jia J. J. , Callcott T A. , Himpsel F. J. , Ederer D. L. , Perera R. C. C. 
Published: April 2011

AbstractWe are using resonant soft x-ray fluorescence at the Advanced Light Source to probe the electronic and geometric structure of novel materials. In the resonant process, a core electron is excited by a photon whose energy is near the core binding energy. In this energy regime the absorption and emission processes are coupled, and this coupling manifests itself in several ways. In boron nitride (BN), the resonant emission spectra reflect the influence of a “spectator” electron in an unoccupied excitonic state. The resonant emission can be used to distinguish between the various bulk phases of BN, and can also be used to probe the electronic structure of a monolayer of BN buried in a bulk environment, where it is inaccessible to electron spectroscopies. For highly-oriented pyrolytic graphite (HOPG) a coherent absorption-emission process takes place in the resonant regime, whereby crystalline momentum is conserved between the core excited electron and the valence hole which remains after emission
Magnetic Compton Scattering Studies of the Invar Effect in Fe3Pt
Authors: Yahnke C. J. , Srajer G. , Haeffner D. R. , Mills D. M. , Assoufid L. 
Published: April 2011

AbstractWe have measured the magnetic Compton profile (MCP) of ordered and disordered Fe 3Pt samples both above and below their Curie temperature. From these measurements, we have determined the average moment per atom at room temperature to be 2.81μB ± 0.04μB for disordered Fe3Pt and 1.78μB ± 0.05μB for ordered Fe3Pt. At temperatures above Tc, we measured a substantial reduction in the moment (0.6μB ± 0.10μB for disordered Fe3Pt and 0.64μB ± 0.13μB ± for ordered Fe3Pt) and a change in the shape of the MCP. This suggests that the mechanism behind the Invar effect in Fe3Pt can be described by a high-spin to low-spin magnetic phase transition. The experimental MCPs for both ordered and disordered Fe3 Pt are analyzed within the framework of the Weiss 2γ model.